JP5494438B2 - Power transmission device and power transmission method for four-wheel drive vehicle - Google Patents

Description

  The present invention relates to a power transmission device and a power transmission method for a four-wheel drive vehicle configured to be switchable between a two-wheel drive state and a four-wheel drive state. In particular, the present invention relates to a mechanism for switching between a two-wheel drive state and a four-wheel drive state and an improvement of a mechanism for switching between a high speed range and a low speed range.

  Some four-wheel drive vehicles have a four-wheel drive state suitable for driving on rough roads (hereinafter sometimes referred to as a four-wheel drive mode) and an energy consumption rate (in the case of an internal combustion engine, a fuel consumption rate). Some have a power distribution mechanism (mode switching mechanism) capable of switching between two-wheel drive states (hereinafter also referred to as two-wheel drive modes) that can be improved. Some have a sub-transmission (range switching mechanism) capable of switching between a high speed range (Hi) for outputting the rotational output from the drive source without decelerating and a low speed range (Lo) for decelerating and outputting. .

  For example, the following Patent Document 1 and Patent Document 2 disclose a vehicle including both the power distribution mechanism and the auxiliary transmission.

  Specifically, the power distribution mechanism includes, for example, a two-wheel drive mode in which rotational power input from a drive source is output only to a rear wheel side output shaft (rear propeller shaft), and rotational power input from a drive source. The four-wheel drive mode for outputting to both the rear wheel side output shaft and the front wheel side output shaft (front propeller shaft) can be switched. As a specific configuration for switching between these modes, as disclosed in each patent document, a clutch is provided between the power transmission path to the rear wheel side output shaft and the power transmission path to the front wheel side output shaft. The mechanism is interposed. In other words, the four-wheel drive mode is set when the clutch mechanism is engaged, and the two-wheel drive mode is set when the clutch mechanism is released.

  Further, the auxiliary transmission is provided with a planetary gear mechanism, and rotational power is output from the planetary gear mechanism via a coupling sleeve (hereinafter simply referred to as a sleeve). That is, the rotational power from the drive source is adjusted through the planetary gear mechanism and the sleeve toward the drive wheels (for example, only the rear wheels in the two-wheel drive mode, and both the front and rear wheels in the four-wheel drive mode). It is configured to output. The sleeve is slidable along the axis by receiving an operating force of an actuator or the like. For example, in the one disclosed in Patent Document 1, a slide position that meshes with a high-speed range piece that is integrally rotated with the carrier of the planetary gear mechanism, and a low-speed range piece that is rotatably disposed adjacent to the ring gear. The sleeve is slidable between the meshing slide positions. When the sleeve moves to the slide position where it engages with the high-speed range piece and the ring gear, the ring gear, the carrier, and the sun gear rotate together, and the high-speed range (the high-speed range where the input rotation speed and the output rotation speed of the planetary gear mechanism match) ) Holds. In addition, when the sleeve moves to the slide position where the sleeve engages with the low-speed range piece and the ring gear, the ring gear and the sun gear can rotate relative to each other. The low-speed range (the output rotational speed is lower than the input rotational speed of the planetary gear mechanism). (Low speed range) is established.

JP 2009-126457 A Japanese Patent Laid-Open No. 10-250395

  As described above, in a vehicle including both a power distribution mechanism and a sub-transmission, the power distribution mechanism and the sub-transmission are arranged as individual mechanisms. For this reason, in the drive force transmission switching mechanism (transfer) incorporating these mechanisms, the configuration is complicated and enlarged, and these can be improved (simplification and downsizing of the configuration). ) Was difficult.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a four-wheel drive having a switching function between a four-wheel drive state and a two-wheel drive state and a switching function between a high speed range and a low speed range. It is an object of the present invention to provide a power transmission device and a power transmission method for a four-wheel drive vehicle capable of simplifying and reducing the size of the drive vehicle.

-Principle of solving the problem-
The solution principle of the present invention devised to achieve the above object is that torque transmission to the front and rear wheels is allowed by allowing rotation of each rotating element (three elements) of the planetary gear mechanism that receives the rotational driving force from the driving source. It is possible to switch between a four-wheel drive state in which rotation is performed and a two-wheel drive state in which the rotation of a specific rotating element is prohibited and torque is transmitted to only one of the front and rear wheels. By disconnecting one of the sub-drive wheels that is not transmitting from the differential device, it is possible to rotate each of the sub-drive wheels connected to this rotary element while prohibiting rotation of the specific rotary element. I have to. As a result, the low-speed mode in the four-wheel drive state and the high-speed mode in the two-wheel drive state (a mode in which the output rotational speed from the planetary gear mechanism is increased with respect to the rotational speed of the drive source) can be established with one mechanism. I have to.

-Solution-
Specifically, the present invention can distribute the driving force from the driving source to the main driving wheel and the auxiliary driving wheel, and transmits the driving force from the driving source only to the main driving wheel without transmitting to the auxiliary driving wheel. A power transmission device for a four-wheel drive vehicle configured to be switchable between a two-wheel drive state and a four-wheel drive state in which a drive force from a drive source is transmitted to both the main drive wheel and the sub drive wheel is assumed. A planetary gear mechanism disposed on a driving force transmission path for transmitting a driving force from a driving source to the power transmission device of the four-wheel drive vehicle includes a first rotating element, a second rotating element, and a third rotating element. The three rotation elements are provided, the drive source is connected to the second rotation element, the main drive wheel is connected to one of the first rotation element and the third rotation element, and the other rotation element is connected to the other rotation element. Connect the auxiliary drive wheels. Further, a rotation stopping means is provided which can be switched between an engaged state in which the other rotating element is in a rotation stopped state and a released state in which the rotation of the other rotating element is allowed. In addition, an engagement means that is switchable between an engagement state in which torque transmission is performed and a release state in which torque transmission is interrupted is disposed between the other rotating element and the auxiliary drive wheel. Then, the rotation stop means is set to the released state and the engagement means is set to the engagement state to set the four-wheel drive state, while the rotation stop means is set to the engagement state and the engagement means is set to the release state to set the main drive. The one rotating element to which the wheel is connected is configured to be in a two-wheel drive state in which the rotational speed is increased with respect to the second rotating element.

  Due to this specific matter, the combination of each state of the rotation stop means and the engagement means, a four-wheel drive state where the rotational speed is not increased (low-speed four-wheel drive state) and a two-wheel drive state where the rotational speed is increased (high speed) Two-wheel drive state) can be established. As a result, a switching function between a four-wheel driving state and a two-wheel driving state that exhibits a center differential function, and a switching function between a high-speed range that can improve the energy consumption rate and a low-speed range that is suitable for rough road driving, starting, etc. Can be realized while simplifying and downsizing the configuration.

  Specific examples of the planetary gear mechanism include the following. First, the planetary gear mechanism is a single pinion type planetary gear mechanism. The first rotating element is a ring gear, the second rotating element is a planetary carrier, and the third rotating element is a sun gear.

  When the planetary gear mechanism is a double pinion type planetary gear mechanism, the first rotating element is a planetary carrier, the second rotating element is a ring gear, and the third rotating element is a sun gear.

  In the single pinion type planetary gear mechanism, the gear ratio ρ is “the number of ring gear teeth / (the number of sun gear teeth + the number of ring gear teeth)”, and it is difficult to set the gear ratio ρ around “0.5”. This is a configuration suitable for unequal distribution of torques to the front wheel side and the rear wheel side. On the other hand, the double pinion type planetary gear mechanism has a gear ratio ρ of “the number of teeth of the sun gear / the number of teeth of the ring gear”, so that the configuration is suitable for equally distributing the torque to the front wheel side and the rear wheel side.

  Specifically, the position of the engagement means is provided between a differential mechanism that allows the differential of the left and right sub drive wheels and one of the sub drive wheels.

  According to this configuration, it is possible to travel in a state where the rotation of the differential mechanism is stopped, and power loss due to the rotation of the differential mechanism can be reduced. As a result, the energy consumption rate can be improved.

  As a specific configuration of the rotation stopping unit and the engaging unit, at least one of them may be configured by a multi-plate clutch.

  According to this configuration, when the switching between the four-wheel driving state and the two-wheel driving state is performed, the engagement force or half-engagement operation of the multi-plate clutch is executed, so that the driving force is released from the driving wheel (driving force). In a state in which the transmission is not transmitted), and it is possible to ensure good running performance at the time of switching.

  Further, as a configuration for switching the driving force transmission state between the four-wheel drive state and the two-wheel drive state, in the four-wheel drive state, after the engagement means is completely released, the rotation stop means is completely engaged. The two-wheel drive state is switched by combining, and in the two-wheel drive state, after the rotation stop means is completely released, the drive means switching means for switching to the four-wheel drive state by completely engaging the engagement means is provided. Yes.

  As a method for switching the driving force transmission state between the four-wheel driving state and the two-wheel driving state, the engagement means is used when switching from the traveling state in the four-wheel driving state to the traveling state in the two-wheel driving state. After completely releasing the rotation stop means, the rotation stop means is completely engaged, and when switching from the running state in the two-wheel drive state to the four-wheel drive state, the rotation stop means is completely released, and then the engagement is stopped. The coupling means is completely engaged.

  In the present invention, a four-wheel drive state in which torque is transmitted to the front and rear wheels by allowing rotation of each rotation element (three elements) of the planetary gear mechanism that receives a rotation driving force from a drive source, and rotation of a specific rotation element The two-wheel drive state in which torque transmission to only one of the front and rear wheels is prohibited and the low-speed mode in the four-wheel drive state and the high-speed mode in the two-wheel drive state are made one mechanism. This is possible. Therefore, the switching function between the four-wheel driving state and the two-wheel driving state and the switching function between the high speed range and the low speed range can be realized while simplifying the configuration and reducing the size.

It is a figure which shows typically the power transmission device of the four-wheel drive vehicle which concerns on 1st Embodiment, Comprising: It is a figure which shows the driving | running | working state in 4WD-Lo mode. It is a figure which shows schematic structure of the control system containing the drive control circuit of a motor generator. It is an alignment chart in the running state in 4WD-Lo mode of a 1st embodiment. It is a figure which shows typically the power transmission device in 4WD-2WD switching mode of 1st Embodiment. It is an alignment chart in 4WD-2WD switching mode of 1st Embodiment. It is a figure which shows typically the power transmission device in the driving | running | working state in 2WD-Hi mode of 1st Embodiment. It is an alignment chart in the running state in 2WD-Hi mode of 1st Embodiment. It is a flowchart figure which shows the procedure of the switching operation | movement from 4WD-Lo mode to 2WD-Hi mode in 1st Embodiment. FIG. 5 is a flowchart illustrating a procedure of switching operation from a 2WD-Hi mode to a 4WD-Lo mode in the first embodiment. It is a figure which shows typically the power transmission device of the four-wheel drive vehicle which concerns on 2nd Embodiment, Comprising: It is a figure which shows the driving state in 4WD-Lo mode. It is a figure which shows typically the power transmission device in 4WD-2WD switching mode of 2nd Embodiment. It is a figure which shows typically the power transmission device in the driving | running | working state in 2WD-Hi mode of 2nd Embodiment. It is a figure which shows typically the power transmission device of the four-wheel drive vehicle which concerns on 3rd Embodiment, Comprising: It is a figure which shows the driving | running | working state in 4WD-Lo mode. It is a figure which shows typically the power transmission device in 4WD-2WD switching mode of 3rd Embodiment. It is a figure which shows typically the power transmission device in the driving | running | working state in 2WD-Hi mode of 3rd Embodiment. It is an alignment chart in 4WD-2WD switching mode of 3rd Embodiment. In 3rd Embodiment, it is a flowchart figure which shows the procedure of the switching operation | movement from 4WD-Lo mode to 2WD-Hi mode. In 3rd Embodiment, it is a flowchart figure which shows the procedure of the switching operation | movement from 2WD-Hi mode to 4WD-Lo mode. It is a figure which shows typically the power transmission device of the four-wheel drive vehicle which concerns on 4th Embodiment, Comprising: It is a figure which shows the driving | running | working state in 4WD-Lo mode. It is an alignment chart in the running state in 4WD-Lo mode of 4th Embodiment. It is a figure which shows typically the power transmission device in 4WD-2WD switching mode of 4th Embodiment. It is an alignment chart in 4WD-2WD switching mode of 4th Embodiment. It is a figure which shows typically the power transmission device in the driving | running | working state in 2WD-Hi mode of 4th Embodiment. It is an alignment chart in the running state in 2WD-Hi mode of 4th Embodiment.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. This embodiment demonstrates the case where this invention is applied to an electric vehicle (Electric Vehicle).

(First embodiment)
First, the first embodiment will be described. In this embodiment, the case where the power transmission device according to the present invention is applied to a four-wheel drive vehicle based on a rear wheel drive will be described. In other words, the driving force is transmitted only to the rear wheels (main driving wheels) in the two-wheel driving mode, and the driving force is transmitted to both the front wheels (sub driving wheels) and the rear wheels in the four-wheel driving mode. A case where the invention is applied will be described.

-Overall configuration of power transmission device-
FIG. 1 is a diagram schematically showing a power transmission device 1 for a four-wheel drive vehicle according to the present embodiment. As shown in FIG. 1, the power transmission device 1 uses a transfer (power distribution mechanism) 3 to transfer the rotational driving force of a motor generator (M / G) 2 as a driving source to the front wheels 4L and 4R and the rear wheels 5L and 5R. It can be distributed to the side. That is, in the two-wheel drive mode, the rotational driving force of the motor generator (drive source) 2 is transmitted to the rear propeller shaft (rear wheel side power transmission shaft) 51 by the transfer 3, and only the rear wheels 5L and 5R are used as drive wheels. Put it in a state. On the other hand, in the four-wheel drive mode, the rotational driving force of the motor generator 2 is transmitted to the front propeller shaft (front wheel side power transmission shaft) 41 and the rear propeller shaft 51 by the transfer 3, respectively, and the front wheels 4L and 4R and the rear wheels 5L and 5R are transmitted. Are in a driving state where both are driven wheels. Hereinafter, each part of the power transmission device 1 will be described.

-Motor generator 2 and its drive circuit-
The motor generator 2 is composed of an AC synchronous motor and functions as a vehicle drive source (motor) and also functions as a generator during regeneration such as when the vehicle is decelerated.

  An outline of the configuration for controlling the driving of the motor generator 2 will be described with reference to FIG. As shown in FIG. 2, the drive circuit of the motor generator 2 includes an inverter 21 for driving the motor generator 2, a chargeable / dischargeable battery 22, a booster that converts electric power from the battery 22 and supplies it to the inverter 21. A converter 23 is provided. Further, a smoothing capacitor 24 is connected to the battery 22 side of the boost converter 23, and a smoothing capacitor 25 is also connected to the inverter 21 side of the boost converter 23.

  Between the terminals of the smoothing capacitors 24 and 25, voltage sensors 61 and 62 for detecting a voltage between these terminals are provided. Further, a temperature sensor 63 for detecting the temperature of the motor generator 2 is disposed in the vicinity of the motor generator 2. Detection signals output from these sensors 61 to 63 are input to the ECU 7 that controls the driving state of the electric vehicle. In addition to the sensors 61, 62, 63, the ECU 7 includes a shift position sensor 64 that detects an operation position of a shift lever operated by a vehicle driver, and an accelerator opening sensor that detects an amount of depression of an accelerator pedal. 65, a brake pedal sensor 66 for detecting the depression amount of the brake pedal, a vehicle speed sensor 67 for detecting the vehicle speed, an atmospheric pressure sensor 68 for detecting the atmospheric pressure, a motor rotation speed sensor 69 for detecting the rotation speed of the motor generator 2, etc. A detection signal is input. Other sensors will be described later.

  The ECU 7 controls the output of the motor generator 2 by switching the switching elements (not shown) of the inverter 21 and the boost converter 23 according to the detection signals from the sensors 61 to 69. As a specific control of the motor generator 2, first, the required torque requested by the driver from the motor generator 2 according to the accelerator opening signal from the accelerator opening sensor 65 and the vehicle speed signal from the vehicle speed sensor 67 is determined. decide. Subsequently, based on the required torque and the rotational speed of the motor generator 2 detected by the motor rotational speed sensor 69, the control voltage to be applied to the inverter 21 is increased as the required torque and the rotational speed of the motor generator 2 are higher. A target voltage to be applied to the inverter 21 is determined by imposing a restriction by a restriction voltage for protecting the motor generator 2 with respect to the control voltage. Then, the switching element of boost converter 23 is controlled so that the voltage acting on inverter 21 becomes the target voltage, and the motor is output within the range of torque that can be output from motor generator 2 with respect to the voltage detected by voltage sensor 62. Switching control of the switching element of the inverter 21 is performed so that the required torque is output from the generator 2.

  By such control of the motor generator 2, the rotational driving force output from the output shaft 26 of the motor generator 2 is transmitted to the transfer 3, and the rotational driving force is transmitted to the rear propeller shaft 51 by the transfer 3 in the two-wheel drive mode. In the four-wheel drive mode, the rotational driving force is transmitted to the front propeller shaft 41 and the rear propeller shaft 51, respectively. As a result, the vehicle travels by outputting the required torque within a range in which the motor generator 2 can be protected. The drive circuit and control operation of the motor generator 2 described above are not limited to this.

  The battery 22 is a secondary battery such as nickel metal hydride or lithium ion, a fuel cell, or the like. In addition, a large-capacity capacitor such as an electric double layer capacitor can be used as a power storage device instead of the battery 22.

  The operation of the transfer 3 in each of the above-described two-wheel drive mode (hereinafter also referred to as 2WD mode) and four-wheel drive mode (hereinafter also referred to as 4WD mode) will be described later.

-Transfer 3-
Next, the transfer 3 which is a characteristic feature of the present embodiment will be described. As shown in FIG. 1, the transfer 3 according to the present embodiment is provided on a driving force transmission path (a driving force transmission path extending from the motor generator 2 to the driving wheel) and includes a single pinion type planetary gear mechanism 30. ing. The planetary gear mechanism 30 includes a sun gear S that is an external gear, a ring gear R that is an internal gear arranged concentrically with the sun gear S, and a plurality of pinion gears P that mesh with the sun gear S and mesh with the ring gear R. And a carrier CA that holds the plurality of pinion gears P so as to rotate and revolve, and the sun gear S, the ring gear R, and the carrier CA are used as rotating elements (first to third rotating elements) to perform a differential action. Has been. In the present embodiment, the ring gear R is the first rotating element referred to in the present invention, the carrier CA is the second rotating element referred to in the present invention, and the sun gear S is the third rotating element referred to in the present invention.

  The output shaft 26 of the motor generator 2 is connected to the carrier (second rotating element) CA of the planetary gear mechanism 30 so as to rotate together. In addition, a cylindrical sleeve member (cylindrical member) 31 through which the output shaft 26 of the motor generator 2 is inserted is connected to the sun gear (third rotating element) S of the planetary gear mechanism 30 in an integrated manner. . The rear propeller shaft 51 is connected to the ring gear (first rotating element) R of the planetary gear mechanism 30 so as to rotate together.

  The rear propeller shaft 51 extends rearward from the transfer 3 and is connected to the rear wheels 5L and 5R via a rear differential gear (differential mechanism) 52 and left and right rear drive shafts 53L and 53R.

  In the rear differential gear 52, a ring gear 52b is integrally provided in a differential case 52a. The ring gear 52b is meshed with a drive pinion gear 51a provided integrally with the rear end portion of the rear propeller shaft 51. The rear differential gear 52 may have any configuration as long as it can perform differential operation for differentially distributing torque to the left and right rear drive shafts 53L and 53R. In the example shown in FIG. 1, as the rear differential gear 52, a gear having a pair of pinion gears 52c, 52c and a pair of side gears 52d, 52d rotating while meshing with each other is used. The pinion gears 52c and 52c and the side gears 52d and 52d are accommodated in the differential case 52a. Lubricating oil (oil) is stored inside the differential case 52a of the rear differential gear 52, and components of the rear differential gear 52 are lubricated by the oil.

  On the other hand, a drive sprocket 32 is rotatably attached to the outer peripheral surface of the sleeve member 31. A driven sprocket 42 is attached to the front propeller shaft 41 so as to rotate integrally. A chain 43 is stretched between the drive sprocket 32 and the driven sprocket 42 so that the rotational force of the drive sprocket 32 is transmitted to the front propeller shaft 41 via the chain 43 and the driven sprocket 42. It has become.

  The front propeller shaft 41 extends from the transfer 3 toward the front of the vehicle body, and is connected to the front wheels 4L and 4R via a front differential gear (differential mechanism) 44 and left and right front drive shafts 45L and 45R. The configuration and function of the front differential gear 44 are the same as those of the rear differential gear 52 described above. In other words, the differential case 44a, the ring gear 44b that meshes with the drive pinion gear 41a of the front propeller shaft 41, the pinion gears 44c and 44c, and the side gears 44d and 44d are provided.

  Further, a two-wheel drive piece 33 having a smaller diameter than that of the drive sprocket 32 is integrally attached to the front side of the drive sprocket 32 on the outer peripheral surface of the sleeve member 31. Splines are formed on the outer peripheral surface of the two-wheel drive piece 33. On the other hand, a locking piece 34 having the same diameter as the two-wheel driving piece 33 is fixed to the vehicle body side. The locking piece 34 is disposed to face the two-wheel drive piece 33, and a spline is formed on the outer peripheral surface thereof. A locking sleeve (rotation stop means) 35 is disposed on the outer peripheral side of the two-wheel drive piece 33 and the locking piece 34. The locking sleeve 35 is slidable along the extending direction (vehicle body longitudinal direction) of the output shaft 26 of the motor generator 2, and the two-wheel drive piece 33 and the locking member are disposed on the inner peripheral surface thereof. Splines that can be engaged with splines formed on the outer peripheral surfaces of the pieces 34 are formed.

  The locking sleeve 35 has a concave portion 35a formed on the outer peripheral surface thereof, and a shift fork (not shown) locked to the concave portion 35a uses an actuator (locking sleeve actuator 36: for example, an electric solenoid or a motor). As the actuator (see FIG. 2) moves, the slide position (slide position shown in FIG. 1) that engages only with the locking piece 34, the locking piece 34, and the two-wheel drive piece It is possible to slide between the slide position (slid position shown in FIG. When the locking sleeve 35 is in a sliding position where only the locking piece 34 is engaged, the two-wheel drive piece 33 is rotatable. That is, the sleeve member 31 and the sun gear S are rotatable. On the other hand, when the locking sleeve 35 is in the sliding position where both the locking piece 34 and the two-wheel driving piece 33 are engaged, the two-wheel driving piece 33 is fixed to the vehicle body side and cannot be rotated. That is, the sleeve member 31 and the sun gear S are fixed to the vehicle body side and cannot be rotated. The transmission state of the rotational driving force and the vehicle running state in each of these states will be described later.

  The configuration for enabling the two-wheel drive piece 33 to be fixed to the vehicle body is not limited to the above. Further, the locking sleeve actuator 36 for slidingly moving the locking sleeve 35 is not limited to an electric type but may be a hydraulic type.

  Of the left and right front drive shafts 45L and 45R, the right front drive shaft 45R has a clutch mechanism 46 (hereinafter referred to as a disconnect mechanism) that switches between transmission and non-transmission of torque to the right front wheel 4R. : Engagement means). The disconnect mechanism 46 is configured to switch between a transmission state in which torque is transmitted between the front differential gear 44 and the right front wheel 4R and a non-transmission state (blocking state) in which torque transmission is not performed.

  Specifically, the right front drive shaft 45R is divided into an inner front drive shaft 45Ra located on the front differential gear 44 side and an outer front drive shaft 45Rb located on the right front wheel 4R side. The disconnect mechanism 46 includes an inner engagement plate 45a attached to the outer end in the vehicle width direction of the inner front drive shaft 45Ra, and an outer engagement plate 45b attached to the inner end in the vehicle width direction of the outer front drive shaft 45Rb. And a sleeve 47 (hereinafter also referred to as a disconnect sleeve) for switching between engagement and disengagement of the engagement plates 45a and 45b.

  The engagement plates 45a and 45b have the same diameter, and splines are formed on the outer peripheral surfaces thereof. On the other hand, on the inner peripheral surface of the disconnect sleeve 47, splines that can be engaged with splines formed on the outer peripheral surfaces of the engagement plates 45a and 45b are formed. The disconnect sleeve 47 has a recess 47a formed on the outer peripheral surface thereof, and a shift fork (not shown) locked to the recess 47a uses an actuator (disconnect sleeve actuator 48: for example, an electric solenoid or a motor). 6 (see FIG. 2)), the slide position (slide position shown in FIG. 6) that engages only with the inner engagement plate 45a (or the outer engagement plate 45b), It is slidable between a slide position (slide position shown in FIG. 1) that engages both the engagement plates 45a and 45b. When the disconnect sleeve 47 is in a slide position where only the one engagement plate 45a (or 45b) is engaged, the torque is not transmitted to the right front wheel 4R (becomes a non-transmission state). On the other hand, when the disconnect sleeve 47 is in the slide position where it engages with both the engagement plates 45a and 45b, the torque can be transmitted to the right front wheel 4R. The transmission state of the rotational driving force and the vehicle running state in each of these states will be described later.

  The disconnect mechanism 46 may have any configuration as long as it can switch transmission / non-transmission of torque between the front differential gear 44 side and the front wheel 4R side. The arrangement location is not particularly limited. Further, the disconnect mechanism 46 may be disposed on the front propeller shaft 41. Further, the disconnect sleeve actuator 48 is not limited to an electric type, and may be a hydraulic type (for example, a hydraulic multi-plate clutch).

  As shown in FIG. 2, the sensors connected to the ECU 7 include a steering angle sensor 81, a locking sleeve position detection sensor 82, a disconnect sleeve position detection sensor, in addition to the sensors 61 to 69 described above. 83, a sleeve rotational speed detection sensor 84, a front drive shaft rotational speed sensor 85, and a wheel rotational speed sensor 86 are provided.

  The steering angle sensor 81 detects the steering angle of a steering wheel (not shown) operated by the driver. Based on this steering angle detection signal, it is determined whether the current traveling state of the vehicle is a straight traveling state or a turning traveling state.

  The locking sleeve position detection sensor 82 detects the sliding movement position of the locking sleeve 35. That is, whether the locking sleeve 35 is in a sliding position (sliding position shown in FIG. 1) that engages only with the locking piece 34, or a sliding position that engages both the locking piece 34 and the two-wheel drive piece 33. It is detected whether it is in the (slide position shown in FIG. 6). A known method such as a potentiometer or an encoder is used as a method for position detection (the disconnect sleeve position detection sensor 83 is also the same).

  The disconnect sleeve position detection sensor 83 detects the slide movement position of the disconnect sleeve 47. That is, the disconnect sleeve 47 is in a slide position (slide position shown in FIG. 6) that engages only with the inner engagement plate 45a or engages with both the inner engagement plate 45a and the outer engagement plate 45b. Whether it is in the slide position (slide position shown in FIG. 1) is detected.

  The sleeve rotation speed detection sensor 84 detects the rotation speed of the sleeve member 31 (corresponding to the rotation speed of the sun gear S). That is, the rotational speed of the sun gear S is detected by detecting the rotational speed of the sleeve member 31.

  The front drive shaft rotational speed sensor 85 detects the rotational speed of the inner front drive shaft 45Ra. The wheel rotation speed sensor 86 detects the rotation speed of the outer front drive shaft 45Rb. The detection signals of these sensors are used to determine whether or not the rotational speed of the inner front drive shaft 45Ra matches the rotational speed of the outer front drive shaft 45Rb (whether or not the rotation is synchronized).

  The ECU 7 includes, for example, an electronic circuit mainly composed of a microcomputer, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes various arithmetic processes based on various control programs and maps stored in the ROM. The RAM is a memory for temporarily storing calculation results in the CPU, data input from the sensors 61 to 69 and 81 to 86, and the like.

  The ECU 7 controls and locks the motor generator 2 based on detection signals from the various sensors 61 to 69 and 81 to 86 and settings of various switches (for example, a 2WD / 4WD changeover switch operated by the driver). Various controls such as control of the locking sleeve actuator 36 for slidably moving the sleeve 35 and control of the disconnect sleeve actuator 48 for slidably moving the disconnect sleeve 47 are performed.

-Vehicle driving mode-
Next, the traveling mode of the vehicle (four-wheel drive vehicle) configured as described above will be described.

  The four-wheel drive vehicle according to the present embodiment is in a four-wheel drive state and in a low speed range (hereinafter sometimes referred to as a 4WD-Lo mode) according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. It is possible to switch between the traveling state in the vehicle and the traveling state in the two-wheel drive state and in the high speed range (hereinafter sometimes referred to as 2WD-Hi mode). This will be specifically described below.

<4WD-Lo mode>
FIG. 1 shows a traveling state in the 4WD-Lo mode. In the 4WD-Lo mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in an engaged state (engaged with both the engaging plates 45a and 45b). State). That is, in the transfer 3, the sun gear S can rotate relative to the carrier CA, and the rotational driving force from the motor generator 2 is distributed from the carrier CA to the ring gear R and the sun gear S. Therefore, the rotational driving force from the motor generator 2 input to the carrier CA is transmitted to the rear wheels 5L and 5R via the ring gear R, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The The rotational driving force from the motor generator 2 input to the carrier CA is the sun gear S, the sleeve member 31, the drive sprocket 32, the chain 43, the driven sprocket 42, the front propeller shaft 41, the front differential gear 44, and each front drive shaft. It is transmitted to the front wheels 4L and 4R via 45L and 45R. As a result, traveling in the 4WD-Lo mode is performed.

  FIG. 3 is a collinear diagram in the traveling state in the 4WD-Lo mode. In this alignment chart, the vertical axis represents the rotation speed, and the length of each arrow represents the magnitude of the torque. Further, from the left side in the figure, the rotation speed of the ring gear R (corresponding to the rotation speed of the rear propeller shaft 51: rear output), the rotation speed of the carrier CA (corresponding to the rotation speed of the output shaft 26 of the motor generator 2), right side The rotational speed of the front wheel 4R (right front output), the rotational speed of the sun gear S (matching the rotational speed of the front propeller shaft 41: front output), and the rotational speed of the left front wheel 4L (left front output). In the figure, ρ is the gear ratio between the sun gear S and the ring gear R. The torque ρTIN is applied to the ring gear R (rear output) relative to the output torque TIN of the motor generator 2. ) Is given a torque of “(1-ρ) TIN”. In addition, an arrow indicated by a broken line in the figure indicates a torque given to the left and right front wheels 4L and 4R by distributing the torque “(1-ρ) TIN” given to the sun gear S (front output). An arrow indicated by a one-dot chain line indicates a reaction force acting on the sun gear S (front output).

  In this way, the rear propeller shaft 51 (rear output) and the front propeller shaft 41 (front output) rotate at a rotational speed approximately equal to the rotational speed (NIN) of the motor generator 2, and the front and rear wheels 4L, 4R, 5L, 5R. Is a four-wheel drive state in which all of these are drive wheels, and a traveling state in a low speed mode (a mode in which the rotation speed of the motor generator 2 is output without increasing).

  Further, in the state shown in FIG. 3, no slip is generated in each of the front wheels 4L and 4R and each of the rear wheels 5L and 5R, and a traveling state in which the rotation speeds are substantially the same is shown. If slip occurs in the rear wheels 5L and 5R, the state shown by the phantom line in FIG. 3 is obtained, and the front wheels 4L and 4R are in contact with the increase in the rotation speed of the carrier CA (matching the rotation speed of the motor generator 2). The rotational difference between the rear wheels 5L and 5R is absorbed. That is, the transfer 3 functions as a center differential. This is the same when a slip occurs in each front wheel 4L, 4R. When a rotational difference occurs between the left and right rear wheels 5L and 5R, the rotational difference is absorbed by the differential operation of the rear differential gear 52, and the rotational difference between the left and right front wheels 4L and 4R is generated. If this occurs, the rotational difference is absorbed by the differential operation of the front differential gear 44.

<2WD-Hi mode>
FIG. 6 shows a traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, the locking sleeve 35 is in an engaged state (a state in which both the locking piece 34 and the two-wheel drive piece 33 are engaged), and the disconnect sleeve 47 of the disconnect mechanism 46 is in a released state ( The state is engaged only with the inner engagement plate 45a). That is, in the transfer 3, the sun gear S is fixed to the vehicle body side and cannot rotate, and the rotational driving force from the motor generator 2 is transmitted from the carrier CA to the ring gear R. At this time, since the sun gear S is fixed to the vehicle body side, a reaction force against the rotation of the carrier CA is obtained, and the rotational driving force is effectively transmitted to the ring gear R. Therefore, the rotational driving force from the motor generator 2 input to the carrier CA is transmitted to the rear wheels 5L and 5R via the ring gear R, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The Further, since the sun gear S is fixed, the rotational driving force is not transmitted to the front propeller shaft 41 side, and the front wheels 4L and 4R are not driving wheels. In this case, the disconnect sleeve 47 is in a released state, and the front differential gear 44 and the right front wheel 4R are separated. For this reason, each front wheel 4L, 4R rotates in the traveling direction (forward direction) as the vehicle travels. Further, as the sun gear S is fixed and the rotation of the front propeller shaft 41 is stopped, the rotation of the differential case 44a of the front differential gear 44 is also stopped. In this case, in the front differential gear 44, the side gears 44d and 44d rotate in opposite directions. That is, the inner front drive shaft 45Ra of the front drive shaft 45R rotates in the direction opposite to the rotation direction of the front wheels 4L and 4R. Thereby, traveling in the 2WD-Hi mode is performed.

  FIG. 7 is a collinear diagram in the traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, since the sun gear S is fixed, the rotational speed of the front output is “0”. On the other hand, the rotational speed NR of the ring gear R (rear output) is higher than the rotational speed NIN of the carrier CA (input). In other words, the speed increasing function that increases the rotation speed (rear output rotation speed) of the ring gear R with respect to the rotation speed (input rotation speed) of the motor generator 2 is exhibited. In this way, the rear propeller shaft 51 rotates while increasing the rotational speed N R of the ring gear R with respect to the rotational speed N IN of the motor generator 2 (while increasing the speed), and the two-wheel drive using the rear wheels 5L and 5R as the driving wheels. In the high-speed mode.

  In FIG. 7, NFL is the rotation speed of the left front drive shaft 45L, and NFR is the rotation speed (reverse rotation) of the inner front drive shaft 45Ra in the right front drive shaft 45R.

  Further, the state shown in FIG. 7 shows a traveling state in which no slip has occurred in each of the rear wheels 5L and 5R. If slip occurs in the rear wheels 5L and 5R, a state indicated by a virtual line in FIG. Note that when a rotational difference occurs between the left and right rear wheels 5L, 5R, the rotational difference is absorbed by the differential operation of the rear differential gear 52.

-Switching operation of the vehicle running state-
Next, the switching operation between the above-described 4WD-Lo mode and 2WD-Hi mode will be described. The outline of this switching operation will be described. For example, when a high torque is required for the drive wheels, such as when the vehicle starts or accelerates, or when the driver sets the 4WD mode with the 2WD / 4WD selector switch. If this is done, the 4WD-Lo mode is set. Further, when the vehicle is running at a constant vehicle speed or when the 2WD / 4WD changeover switch is used to set the 2WD mode, the 2WD-Hi mode is set. As described above, these switching operations are switched by the operations of the locking sleeve 35 and the disconnect sleeve 47 (the operation of the locking sleeve actuator 36 and the operation of the disconnect sleeve actuator 48). In this case, when switching from the 4WD-Lo mode to the 2WD-Hi mode, the disconnect sleeve 47 is first switched from the engaged state to the released state, and then the locking sleeve 35 is switched from the released state to the engaged state. It will be. Conversely, when switching from the 2WD-Hi mode to the 4WD-Lo mode, first, after the locking sleeve 35 is switched from the engaged state to the released state, the disconnect sleeve 47 is switched from the released state to the engaged state. (The mode switching operation by the drive mode switching means in the present invention). This will be specifically described below.

<4WD-2WD switching mode>
FIG. 4 is a diagram schematically showing the power transmission device in the 4WD-2WD switching mode during the mode switching. As shown in FIG. 4, in the 4WD-2WD switching mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in a released state (inner engagement plate 45a). Only engaged). That is, in the transfer 3, the sun gear S can rotate relative to the carrier CA, and the rotational driving force from the motor generator 2 is distributed from the carrier CA to the ring gear R and the sun gear S.

  FIG. 5 is an alignment chart in the 4WD-2WD switching mode. In the 4WD-2WD switching mode, at the time of switching to the 2WD-Hi mode, control is performed to reduce the rotational speed of the motor generator 2 (the rotational speed of the carrier CA), and the rotational speed of the carrier CA (the input rotational speed). ) Is reduced, the rotational speed of the sun gear S (front output rotational speed) is decreased toward “0”. That is, the rotational speed of the sun gear S (front output rotational speed) without decreasing the rotational speed of the ring gear R (rear output) or the left front output rotational speed (actually, it is gradually decreased due to road running resistance). ). Thus, by reducing the rotation speed of the sun gear S, the unlocked locking sleeve 35 can be fitted into the spline of the two-wheel drive piece 33. On the other hand, at the time of switching to the 4WD-Lo mode, control for increasing the rotation speed of the motor generator 2 (the rotation speed of the carrier CA) is executed, and by increasing the rotation speed of the carrier CA (the input rotation speed), the sun gear S Increase the rotational speed (front output rotational speed) and bring the right front output rotational speed (the rotational speed NFR of the inner front drive shaft 45Ra) closer to the left front output rotational speed NFL (matches the rotational speed of the outer front drive shaft 45Rb). Go. By increasing the right front output rotational speed in this way, the disconnected sleeve 47 in the released state is brought into a state where it can engage with the spline of the outer engagement plate 45b.

<Switching operation from 4WD-Lo mode to 2WD-Hi mode>
Next, the switching operation from the 4WD-Lo mode to the 2WD-Hi mode will be specifically described. FIG. 8 is a flowchart showing the procedure of the switching operation from the 4WD-Lo mode to the 2WD-Hi mode.

  First, in step ST1, the current driving state of the vehicle is at the time of starting or accelerating, and the vehicle moves from the state where the vehicle is traveling in the 4WD-Lo mode to the constant vehicle speed traveling state. It is determined whether or not a request for switching to is made. When the current vehicle running state is not the 4WD-Lo mode or when the request for switching to the 2WD-Hi mode has not been made, a NO determination is made at step ST1 and the process returns.

  When a request for switching from the 4WD-Lo mode to the 2WD-Hi mode is made, and if YES is determined in step ST1, the process proceeds to step ST2, and it is determined whether or not the current traveling state of the vehicle is a straight traveling state. This determination is made based on the vehicle speed detection signal from the vehicle speed sensor 67 and the steering angle detection signal of the steering wheel from the steering angle sensor 81. That is, it is determined that the vehicle is traveling straight when the vehicle is traveling and the steering angle of the steering wheel is approximately “0”.

  When the traveling state of the vehicle is not a straight traveling state but a NO determination is made in step ST2, it is determined that the vehicle is stopped or traveling in a turn and the mode switching operation is prohibited and the process returns.

  On the other hand, when the traveling state of the vehicle is a straight traveling state and a YES determination is made in step ST2, the process proceeds to step ST3, where torque down control of the motor generator 2 is executed. This torque-down control is a control for shifting from the 4WD-Lo mode to the 4WD-2WD switching mode, in order to enable the release operation of the disconnect sleeve 47 that has been engaged in the 4WD-Lo mode. Done. That is, it is performed to facilitate the release operation of the disconnect sleeve 47 by reducing the torque transmitted to the front drive shaft 45R.

  In step ST4, it is determined whether or not the torque of the motor generator 2 (motor torque) has decreased below a predetermined value. If it has not yet dropped below the predetermined value, a NO determination is made at step ST4, and torque down control is continued until the torque of the motor generator 2 drops below the predetermined value (step ST3). This predetermined value is set in advance by experiment or simulation, and is set as a value that allows the disconnect sleeve 47 to be easily released.

  If the torque of the motor generator 2 falls below a predetermined value and a YES determination is made in step ST4, the process proceeds to step ST5, and a release command signal for the disconnect sleeve 47 is transmitted to the disconnect sleeve actuator 48. As a result, the disconnect sleeve actuator 48 operates, and the disconnect sleeve 47 slides from the engaged state to the released state.

  In step ST6, it is determined whether or not the disconnect sleeve 47 has been released. That is, it is determined whether or not the amount of slide movement of the disconnect sleeve 47 has reached the amount of disengagement from the outer engagement plate 45b. This determination is made based on the detection signal of the disconnect sleeve position detection sensor 83.

  If the disconnect sleeve 47 has not yet been released and a NO determination is made in step ST6, a release command signal for the disconnect sleeve actuator 48 is continuously transmitted (step ST5).

  If the disconnect sleeve 47 is in the released state and YES is determined in step ST6, that is, if the 4WD-2WD switching mode is established, the process proceeds to step ST7, and synchronous control of the motor generator 2 is executed. This synchronization control is a control for shifting from the 4WD-2WD switching mode to the 2WD-Hi mode, and the engagement operation of the locking sleeve 35 that has been released in the 4WD-Lo mode and the 4WD-2WD switching mode. Done to make it possible. That is, it is performed in order to facilitate the engaging operation of the locking sleeve 35 by reducing the rotational speed of the sun gear S (by setting the rotational speed to “0”). Specifically, the rotational speed of the motor generator 2 is gradually lowered, and the rotational speed of the sun gear S (front output) is lowered as shown in the collinear charts of FIGS.

  In step ST8, due to the synchronous control of the motor generator 2, the rotational speed of the sun gear S is the synchronous rotational speed of the two-wheel drive piece 33 and the locking piece 34 (synchronous rotational speed at which the locking sleeve 35 can be engaged). It is determined whether or not it has been reached. Specifically, since the locking piece 34 is fixed to the vehicle body side, the synchronous rotation speed is set to approximately “0”. That is, the rotational speed of the two-wheel drive piece 33 (corresponding to the rotational speed of the sleeve member 31 and the sun gear S) is detected by the sleeve rotational speed detection sensor 84, and the detected rotational speed has reached substantially “0”. At this point, it is determined that the two-wheel drive piece 33 has reached the synchronous rotational speed.

  If the two-wheel drive piece 33 has not reached the synchronous rotation speed and NO is determined in step ST8, the synchronous control of the motor generator 2 is continued (step ST7).

  If the two-wheel drive piece 33 reaches the synchronous rotation speed and the determination in step ST8 is YES, the process proceeds to step ST9, and an engagement command signal for the locking sleeve 35 is transmitted to the locking sleeve actuator 36. As a result, the locking sleeve actuator 36 operates, and the locking sleeve 35 slides from the released state toward the engaged state.

  In step ST10, it is determined whether or not the locking sleeve 35 is engaged. That is, it is determined whether or not the sliding movement amount of the locking sleeve 35 has reached the amount that engages with the two-wheel drive piece 33. This determination is made based on the detection signal of the locking sleeve position detection sensor 82.

  If the locking sleeve 35 is not yet engaged and the determination is NO in step ST10, an engagement command signal for the locking sleeve actuator 36 is continuously transmitted (step ST9).

  If the locking sleeve 35 is in the engaged state and a YES determination is made in step ST10, the process proceeds to step ST11 and the running torque control of the motor generator 2 is executed. In this running torque control, the motor generator 2 is controlled such that a required torque determined according to the accelerator opening detected by the accelerator opening sensor 65 and the vehicle speed detected by the vehicle speed sensor 67 is output.

  With the above operation, the switching operation from the 4WD-Lo mode to the 2WD-Hi mode is completed.

<Switching operation from 2WD-Hi mode to 4WD-Lo mode>
Next, the switching operation from the 2WD-Hi mode to the 4WD-Lo mode will be specifically described. FIG. 9 is a flowchart showing the procedure of the switching operation from the 2WD-Hi mode to the 4WD-Lo mode.

  First, in step ST21, whether or not a request for switching to the 4WD-Lo mode is made by an acceleration request or the like from a state in which the current vehicle traveling state is a constant vehicle speed traveling state or the like and the vehicle is traveling in the 2WD-Hi mode. Determine. If the current vehicle running state is not the 2WD-Hi mode or if a request for switching to the 4WD-Lo mode has not been made, a NO determination is made in step ST21 and the process returns.

  When a request for switching from the 2WD-Hi mode to the 4WD-Lo mode is made and a YES determination is made in step ST21, the operation proceeds to step ST22 and subsequent steps. The operations in steps ST22 to ST24 in the flowchart shown in FIG. 9 are the same as the steps ST2 to ST4 in the flowchart shown in FIG. 8 in the switching operation from the 4WD-Lo mode to the 2WD-Hi mode described above. Explanation here is omitted.

  If the torque of the motor generator 2 falls below a predetermined value and a YES determination is made in step ST24, the process proceeds to step ST25, and a release command signal for the locking sleeve 35 is transmitted to the locking sleeve actuator 36. As a result, the locking sleeve actuator 36 operates, and the locking sleeve 35 slides from the engaged state toward the released state.

  In step ST26, it is determined whether or not the locking sleeve 35 has been released. In other words, it is determined whether or not the sliding movement amount of the locking sleeve 35 has reached the amount of separation from the two-wheel drive piece 33. This determination is made based on the detection signal of the locking sleeve position detection sensor 82.

  If the locking sleeve 35 has not yet been released and a NO determination is made in step ST26, a release command signal for the locking sleeve actuator 36 is continuously transmitted (step ST25).

  If the locking sleeve 35 is in the released state and a YES determination is made in step ST26, that is, if the 4WD-2WD switching mode is established, the process proceeds to step ST27, and synchronous control of the motor generator 2 is executed. This synchronization control is a control for shifting from the 4WD-2WD switching mode to the 4WD-Lo mode, and the engagement operation of the disconnect sleeve 47 that has been released in the 2WD-Hi mode and the 4WD-2WD switching mode is performed. Done to make it possible. That is, the rotational speed of the motor generator 2 is increased, and the inner front drive shaft 45Ra is rotated to the forward rotation side via the sun gear S, the front propeller shaft 41, and the front differential gear 44. As a result, the rotational speed of the inner front drive shaft 45Ra is brought closer to the rotational speed of the outer front drive shaft 45Rb. Specifically, the rotational speed of the motor generator 2 is gradually increased, and the rotational speed of the sun gear S (front output) is increased as shown in the collinear diagrams of FIGS. The rotational speed (the rotational speed (NFR) of the inner front drive shaft 45Ra) is increased.

  In step ST28, it is determined by the synchronous control of the motor generator 2 whether the rotational speed of the inner front drive shaft 45Ra is synchronized with the rotational speed of the outer front drive shaft 45Rb. That is, it is determined whether or not the synchronous rotation speed at which the disconnect sleeve 47 can be engaged has been reached.

  If the inner front drive shaft 45Ra has not reached the synchronous rotation speed and NO is determined in step ST28, the synchronous control of the motor generator 2 is continued (step ST27).

  If the inner front drive shaft 45Ra reaches the synchronous rotation speed and the determination in step ST28 is YES, the process proceeds to step ST29, and an engagement command signal for the disconnect sleeve 47 is transmitted to the disconnect sleeve actuator 48. As a result, the disconnect sleeve actuator 48 operates, and the disconnect sleeve 47 slides from the released state toward the engaged state.

  In step ST30, it is determined whether or not the disconnect sleeve 47 is engaged. That is, it is determined whether or not the amount of slide movement of the disconnect sleeve 47 has reached the amount of engagement with the outer engagement plate 45b. This determination is made based on the detection signal of the disconnect sleeve position detection sensor 83.

  If the disconnect sleeve 47 is not yet engaged and the determination is NO in step ST30, an engagement command signal for the disconnect sleeve actuator 48 is continuously transmitted (step ST29).

  If the disconnect sleeve 47 is in the engaged state and the determination in step ST30 is YES, the process proceeds to step ST31, and the running torque control of the motor generator 2 is executed. In this running torque control, the motor generator 2 is controlled such that a required torque determined according to the accelerator opening detected by the accelerator opening sensor 65 and the vehicle speed detected by the vehicle speed sensor 67 is output.

  With the above operation, the switching operation from the 2WD-Hi mode to the 4WD-Lo mode is completed.

  As described above, in the present embodiment, the 4WD-Lo mode and the 2WD-Hi mode can be switched according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. That is, the switching function between the four-wheel driving state and the two-wheel driving state and the switching function between the high speed range and the low speed range are made compatible by one mechanism, and the transfer 3 functions as a center differential in the 4WD-Lo mode. In the Hi mode, the transfer 3 can function as a speed increasing device. For this reason, for example, securing of high start performance in the 4WD-Lo mode and improvement of the energy consumption rate in the 2WD-Hi mode can be achieved by one mechanism. In the prior art, the power distribution mechanism for switching between the four-wheel drive state and the two-wheel drive state and the sub-transmission for switching between the high speed range and the low speed range are provided as separate mechanisms, respectively. It has become complicated and large. On the other hand, according to the present embodiment, it is not necessary to dispose the power distribution mechanism and the auxiliary transmission as separate mechanisms, and as a result, it is possible to simplify the configuration and reduce the size. In addition, the manufacturing cost can be reduced with the simplification of the configuration.

(Second Embodiment)
Next, a second embodiment will be described. In the present embodiment, a case where the power transmission device according to the present invention is applied to a four-wheel drive vehicle based on a front wheel drive will be described. That is, the present invention is applied to a four-wheel drive vehicle in which driving force is transmitted only to the front wheels (main driving wheels) in the two-wheel driving mode, and driving force is transmitted to both front wheels and rear wheels (sub driving wheels) in the four-wheel driving mode. The case where is applied will be described.

-Overall configuration of power transmission device-
FIG. 10 is a diagram schematically showing the power transmission device 1 of the four-wheel drive vehicle according to the present embodiment. As shown in FIG. 10, the power transmission device 1 according to the present embodiment also uses a transfer (power distribution mechanism) 3 to transfer the rotational driving force of a motor generator (M / G) 2 that is a driving source to the front wheels 4L and 4R side. The rear wheel 5L, 5R can be distributed. In the two-wheel drive mode, the rotational driving force of the motor generator 2 is transmitted to the front drive shafts 45L and 45R by the transfer 3 so that only the front wheels 4L and 4R are driven wheels. On the other hand, in the four-wheel drive mode, the rotational driving force of the motor generator 2 is transmitted to the front drive shafts 45L and 45R and the rear propeller shaft 51 by the transfer 3, respectively, and the front wheels 4L and 4R and the rear wheels 5L and 5R are both driven wheels. To the running state. Hereinafter, each part of the power transmission device 1 will be described. In the following description, the same components as those in the first embodiment described above are denoted by the same reference numerals in FIG. 10 and description thereof is omitted.

  The configuration of the motor generator 2 and its drive circuit are the same as those in the first embodiment. Note that the motor generator 2 in the present embodiment has a horizontally arranged output shaft 26 extending in the vehicle width direction, and a rotational driving force is applied to the carrier CA of the transfer 3 described later at the tip of the output shaft 26. The drive gear 27 for transmitting is provided integrally with the rotation.

-Transfer 3-
The transfer 3 in the power transmission device according to the present embodiment will be described. As shown in FIG. 10, the transfer 3 according to this embodiment includes a single pinion type planetary gear mechanism 30. The configuration of the planetary gear mechanism 30 is substantially the same as that of the first embodiment.

  A driven gear 37 is provided integrally with the carrier (second rotating element) CA of the planetary gear mechanism 30, and the driven gear 37 meshes with a drive gear 27 provided on the output shaft 26 of the motor generator 2. . That is, the rotational driving force of the motor generator 2 is transmitted to the carrier CA via the drive gear 27 and the driven gear 37.

  The sun gear (third rotating element) S of the planetary gear mechanism 30 is a cylindrical sleeve member (cylindrical member) into which the right front drive shaft 45R (front drive shaft 45R connected to the right front wheel 4R) is inserted. 31 is connected to rotate integrally. A differential case 44a of the front differential gear 44 is connected to the ring gear (first rotating element) R of the planetary gear mechanism 30 in a rotationally integrated manner.

  The front drive shafts 45L and 45R extend in the vehicle width direction. The left front drive shaft 45L is rotatably connected to the left side gear 44d of the front differential gear 44, and the right front drive shaft 45R is rotatably connected to the right side gear 44d of the front differential gear 44. That is, the front drive shafts 45L and 45R are connected to the ring gear R of the transfer 3 via the front differential gear 44. The internal configuration of the front differential gear 44 is substantially the same as that of the first embodiment.

  On the other hand, a drive gear 38 is rotatably attached to the outer peripheral surface of the sleeve member 31. A driven gear 54 is rotatably attached to the front end of the rear propeller shaft 51. Since the drive gear 38 and the driven gear 54 are engaged with each other, the rotational force of the drive gear 38 is transmitted to the rear propeller shaft 51 via the driven gear 54.

  The rear propeller shaft 51 extends toward the rear of the vehicle body and is connected to the rear wheels 5L and 5R via a rear differential gear 52 and left and right rear drive shafts 53L and 53R. The configuration and function of the rear differential gear 52 are substantially the same as those of the first embodiment.

  Further, a two-wheel drive piece 33 having a smaller diameter than that of the drive gear 38 is integrally attached to the outer side (right side) of the drive gear 38 on the outer peripheral surface of the sleeve member 31. Splines are formed on the outer peripheral surface of the two-wheel drive piece 33. On the other hand, a locking piece 34 having the same diameter as the two-wheel driving piece 33 is fixed to the vehicle body side. The locking piece 34 also has a spline formed on the outer peripheral surface thereof. A locking sleeve 35 is arranged on the outer peripheral side of the two-wheel drive piece 33 and the locking piece 34. The locking sleeve 35 is slidable along the extending direction (vehicle width direction) of the front drive shaft 45R, and the inner peripheral surface of the two-wheel drive piece 33 and the locking piece 34 Splines that can be engaged with splines formed on the outer peripheral surfaces are formed.

  The locking sleeve 35 has a recess 35a formed on the outer peripheral surface thereof, and a shift fork (not shown) locked to the recess 35a moves in accordance with the operation of the locking sleeve actuator 36 (for example, an electric actuator). Accordingly, the slide position (slide position shown in FIG. 10) that engages only with the locking piece 34 and the slide position (slide shown in FIG. 12) that engages both the locking piece 34 and the two-wheel drive piece 33. Position). When the locking sleeve 35 is in a sliding position where only the locking piece 34 is engaged, the two-wheel drive piece 33 is rotatable. That is, the sleeve member 31 and the sun gear S are rotatable. On the other hand, when the locking sleeve 35 is in the sliding position where both the locking piece 34 and the two-wheel driving piece 33 are engaged, the two-wheel driving piece 33 is fixed to the vehicle body side and cannot be rotated. That is, the sleeve member 31 and the sun gear S are fixed to the vehicle body side and cannot be rotated. The transmission state of the rotational driving force and the vehicle running state in each of these states will be described later.

  The configuration for enabling the two-wheel drive piece 33 to be fixed to the vehicle body is not limited to the above. Further, the locking sleeve actuator 36 for slidingly moving the locking sleeve 35 is not limited to an electric type but may be a hydraulic type.

  Of the left and right rear drive shafts 53L, 53R, the left rear drive shaft 53L is provided with a disconnect mechanism 46 for switching transmission / non-transmission of torque to the left rear wheel 5L. The disconnect mechanism 46 is configured to switch between a transmission state in which torque is transmitted between the rear differential gear 52 and the left rear wheel 5L and a non-transmission state (blocking state) in which torque transmission is not performed. .

  Specifically, the left rear drive shaft 53L is divided into an inner rear drive shaft 53La located on the rear differential gear 52 side and an outer rear drive shaft 53Lb located on the left rear wheel 5L side. The disconnect mechanism 46 includes an inner engagement plate 53a attached to the outer end in the vehicle width direction of the inner rear drive shaft 53La, and an outer engagement plate 53b attached to the inner end in the vehicle width direction of the outer rear drive shaft 53Lb. And a disconnect sleeve 47 for switching between engagement and disengagement of the engagement plates 53a and 53b.

  The engagement plates 53a and 53b have the same diameter, and splines are formed on the outer peripheral surfaces thereof. On the other hand, on the inner peripheral surface of the disconnect sleeve 47, splines that can be engaged with the splines formed on the outer peripheral surfaces of the engagement plates 53a, 53b are formed. The disconnect sleeve 47 has a recess 47a formed on the outer peripheral surface thereof, and a shift fork (not shown) locked to the recess 47a moves in accordance with the operation of the disconnect sleeve actuator 48 (for example, an electric actuator). By doing so, a slide position (slide position shown in FIG. 12) that engages only with the inner engagement plate 53a (or the outer engagement plate 53b) and a slide position that engages with both the engagement plates 53a and 53b ( (Sliding position shown in FIG. 10). When the disconnect sleeve 47 is in a slide position where only the one engagement plate 53a (or 53b) is engaged, torque is not transmitted to the left rear wheel 5L (becomes a non-transmission state). . On the other hand, when the disconnect sleeve 47 is in the slide position where it engages with both the engagement plates 53a and 53b, the torque can be transmitted to the left rear wheel 5L. The transmission state of the rotational driving force and the vehicle running state in each of these states will be described later.

  The disconnect mechanism 46 may have any configuration as long as it can switch transmission / non-transmission of torque between the rear differential gear 52 side and the rear wheel 5L side. However, the arrangement location is not particularly limited. Further, the disconnect mechanism 46 may be disposed on the rear propeller shaft 51. Further, the disconnect sleeve actuator 48 is not limited to an electric type, and may be a hydraulic type (for example, a hydraulic multi-plate clutch).

  Other configurations are substantially the same as those of the first embodiment described above.

-Vehicle driving mode-
Next, the traveling mode of the vehicle (four-wheel drive vehicle) configured as described above will be described.

  As in the case of the first embodiment, the four-wheel drive vehicle according to the present embodiment has a traveling state in the 4WD-Lo mode and a 2WD according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. -The driving state in Hi mode can be switched. This will be specifically described below.

<4WD-Lo mode>
FIG. 10 shows a traveling state in the 4WD-Lo mode. In the 4WD-Lo mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in an engaged state (engaged with both the engaging plates 53a and 53b). State). That is, in the transfer 3, the sun gear S can rotate relative to the carrier CA, and the rotational driving force from the motor generator 2 passes from the carrier CA to the ring gear R and the sun gear via the drive gear 27 and the driven gear 37. Distributed to S. For this reason, the rotational driving force from the motor generator 2 input to the carrier CA is transmitted to the front wheels 4L and 4R via the ring gear R, the front differential gear 44, and the front drive shafts 45L and 45R. The rotational driving force from the motor generator 2 input to the carrier CA is applied to the sun gear S, the sleeve member 31, the drive gear 38, the driven gear 54, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. Then, it is transmitted to the rear wheels 5L and 5R. As a result, traveling in the 4WD-Lo mode is performed. The nomographic chart in the traveling state in the 4WD-Lo mode only replaces the front and rear in FIG. 3 in the first embodiment, and the description thereof is omitted here. That is, the ring gear R is a front output and the sun gear S is a rear output.

<2WD-Hi mode>
FIG. 12 shows a traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, the locking sleeve 35 is in an engaged state (a state in which both the locking piece 34 and the two-wheel drive piece 33 are engaged), and the disconnect sleeve 47 of the disconnect mechanism 46 is in a released state ( The state is engaged only with the inner engagement plate 53a). That is, in the transfer 3, the sun gear S is fixed to the vehicle body side and cannot rotate, and the rotational driving force from the motor generator 2 is transmitted from the carrier CA to the ring gear R. At this time, since the sun gear S is fixed to the vehicle body side, a reaction force against the rotation of the carrier CA is obtained, and the rotational driving force is effectively transmitted to the ring gear R. For this reason, the rotational driving force from the motor generator 2 input to the carrier CA through the drive gear 27 and the driven gear 37 passes through the ring gear R, the front differential gear 44, and the front drive shafts 45L and 45R, and the front wheels 4L and 4R. Is transmitted to. Further, since the sun gear S is fixed, the rotational driving force is not transmitted to the rear propeller shaft 51 side, and the rear wheels 5L and 5R are not driving wheels. In this case, the disconnect sleeve 47 is in a released state, and the rear differential gear 52 and the left rear wheel 5L are separated. For this reason, each rear wheel 5L, 5R rotates in the traveling direction (forward direction) as the vehicle travels. Further, as the sun gear S is fixed and the rotation of the rear propeller shaft 51 is stopped, the rotation of the differential case 52a of the rear differential gear 52 is also stopped. In this case, in the rear differential gear 52, the side gears 52d and 52d rotate in opposite directions. That is, the inner rear drive shaft 53La of the rear drive shaft 53L rotates in the direction opposite to the rotation direction of the rear wheels 5L and 5R. Thereby, traveling in the 2WD-Hi mode is performed. Since the nomographic chart in the traveling state in the 2WD-Hi mode only replaces the front and rear in FIG. 7 in the first embodiment, description thereof is omitted here. That is, the ring gear R is a front output and the sun gear S is a rear output.

-Switching operation of the vehicle running state-
Next, the switching operation between the above-described 4WD-Lo mode and 2WD-Hi mode will be described. The switching operation in the present embodiment is also switched by the operations of the locking sleeve 35 and the disconnect sleeve 47 (the operation of the locking sleeve actuator 36 and the operation of the disconnect sleeve actuator 48). In this case, when switching from the 4WD-Lo mode to the 2WD-Hi mode, the disconnect sleeve 47 is first switched from the engaged state to the released state, and then the locking sleeve 35 is switched from the released state to the engaged state. It will be. Conversely, when switching from the 2WD-Hi mode to the 4WD-Lo mode, first, after the locking sleeve 35 is switched from the engaged state to the released state, the disconnect sleeve 47 is switched from the released state to the engaged state. It will be. (Mode switching operation by drive mode switching means in the present invention) Hereinafter, a specific description will be given.

<4WD-2WD switching mode>
FIG. 11 is a diagram schematically showing the power transmission device in the 4WD-2WD switching mode during mode switching. As shown in FIG. 11, in the 4WD-2WD switching mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in a released state (inner engagement plate 53a). Only engaged). That is, in the transfer 3, the sun gear S can rotate relative to the carrier CA, and the rotational driving force from the motor generator 2 is distributed from the carrier CA to the ring gear R and the sun gear S.

  In the 4WD-2WD switching mode, at the time of switching to the 2WD-Hi mode, control for reducing the rotational speed of the motor generator 2 (the rotational speed of the carrier CA) is executed, and the rotational speed of the carrier CA (the input rotational speed). Is reduced to decrease the rotational speed of the sun gear S toward “0”. That is, the rotational speed of the sun gear S is decreased without decreasing the rotational speed of the ring gear R (front output) (actually, it is gradually decreased due to the road running resistance). Thus, by reducing the rotation speed of the sun gear S, the unlocked locking sleeve 35 can be fitted into the spline of the two-wheel drive piece 33. On the other hand, at the time of switching to the 4WD-Lo mode, control for increasing the rotation speed of the motor generator 2 (the rotation speed of the carrier CA) is executed, and by increasing the rotation speed of the carrier CA (the input rotation speed), the sun gear S The rotational speed (rear output rotational speed) is increased, and the left rear output rotational speed (rotational speed of the inner rear drive shaft 53La) is brought closer to the rotational speed of the outer rear drive shaft 53Lb. By increasing the left rear output rotational speed in this manner, the disconnected sleeve 47 in the released state is brought into a state where it can engage with the spline of the outer engagement plate 53b.

  Note that the procedure of these switching operations is substantially the same as that described with reference to the flowcharts of FIGS. 8 and 9 in the above-described first embodiment, and thus the description thereof is omitted here.

  Even in the present embodiment, the 4WD-Lo mode and the 2WD-Hi mode can be switched according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. That is, the switching function between the four-wheel driving state and the two-wheel driving state and the switching function between the high speed range and the low speed range can be made compatible by one mechanism. For this reason, it is not necessary to dispose the power distribution mechanism and the sub-transmission as separate mechanisms, and as a result, it is possible to simplify the configuration and reduce the size. In addition, the manufacturing cost can be reduced with the simplification of the configuration.

(Third embodiment)
Next, a third embodiment will be described. In this embodiment, the case where the power transmission device according to the present invention is applied to a four-wheel drive vehicle based on a rear wheel drive will be described. Further, the power transmission device in the present embodiment is different from that in the first embodiment in the configuration of the transfer 3. Therefore, in the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 13 is a diagram schematically showing the power transmission device 1 of the four-wheel drive vehicle according to the present embodiment. As shown in FIG. 10, in the power transmission device 1 according to the present embodiment, a multi-plate clutch mechanism 39 is provided on the sleeve member 31 that is rotatably coupled to the sun gear S. That is, the clutch mechanism 39 is provided in place of the two-wheel drive piece 33, the lock piece 34, and the lock sleeve 35 in the first embodiment described above. The clutch mechanism 39 may be an electromagnetic type or a hydraulic type as long as the engagement force can be adjusted. Since other configurations are substantially the same as those of the first embodiment described above, the same components as those of the first embodiment described above are denoted by the same reference numerals in FIG. 13 and description thereof is omitted.

-Vehicle Travel Mode Next, the travel mode of the vehicle (four-wheel drive vehicle) in the present embodiment will be described.

  The four-wheel drive vehicle according to the present embodiment can be switched between the 4WD-Lo mode and the 2WD-Hi mode according to the engagement state of the clutch mechanism 39 and the slide movement position of the disconnect sleeve 47. . This will be specifically described below.

<4WD-Lo mode>
FIG. 13 shows a traveling state in the 4WD-Lo mode. In the 4WD-Lo mode, the clutch mechanism 39 is in a released state (a state in which the rotation of the sun gear S is allowed), and the disconnect sleeve 47 is in an engaged state (a state in which both the engagement plates 45a and 45b are engaged). It has become. That is, in the transfer 3, the sun gear S can rotate relative to the carrier CA, and the rotational driving force from the motor generator 2 is distributed from the carrier CA to the ring gear R and the sun gear S. Therefore, the rotational driving force from the motor generator 2 input to the carrier CA is transmitted to the rear wheels 5L and 5R via the ring gear R, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The The rotational driving force from the motor generator 2 input to the carrier CA is the sun gear S, the sleeve member 31, the drive sprocket 32, the chain 43, the driven sprocket 42, the front propeller shaft 41, the front differential gear 44, and each front drive shaft. It is transmitted to the front wheels 4L and 4R via 45L and 45R. As a result, traveling in the 4WD-Lo mode is performed. Since the alignment chart in the traveling state in the 4WD-Lo mode is the same as that in FIG. 3 in the first embodiment, description thereof is omitted here.

<2WD-Hi mode>
FIG. 15 shows a traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, the clutch mechanism 39 is in an engaged state (a state in which the rotation of the sun gear S is prohibited), and the disconnect sleeve 47 of the disconnect mechanism 46 is in a released state (only the inner engagement plate 45a is engaged). State). That is, in the transfer 3, the sun gear S is fixed to the vehicle body side and cannot rotate, and the rotational driving force from the motor generator 2 is transmitted from the carrier CA to the ring gear R. At this time, since the sun gear S is fixed to the vehicle body side, a reaction force against the rotation of the carrier CA is obtained, and the rotational driving force is effectively transmitted to the ring gear R. Therefore, the rotational driving force from the motor generator 2 input to the carrier CA is transmitted to the rear wheels 5L and 5R via the ring gear R, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The Further, since the sun gear S is fixed, the rotational driving force is not transmitted to the front propeller shaft 41 side, and the front wheels 4L and 4R are not driving wheels. In this case, the disconnect sleeve 47 is in a released state, and the front differential gear 44 and the right front wheel 4R are separated. For this reason, each front wheel 4L, 4R rotates in the traveling direction (forward direction) as the vehicle travels. Further, as the sun gear S is fixed and the rotation of the front propeller shaft 41 is stopped, the rotation of the differential case 44a of the front differential gear 44 is also stopped. In this case, in the front differential gear 44, the side gears 44d and 44d rotate in opposite directions. That is, the inner front drive shaft 45Ra of the front drive shaft 45R rotates in the direction opposite to the rotation direction of the front wheels 4L and 4R. Thereby, traveling in the 2WD-Hi mode is performed. Since the alignment chart in the traveling state in the 2WD-Hi mode is the same as that in FIG. 7 in the first embodiment, description thereof is omitted here.

-Switching operation of the vehicle running state-
Next, switching operation between the 4WD-Lo mode and the 2WD-Hi mode in the present embodiment will be described. This switching operation is switched by the operation of the clutch mechanism 39 and the disconnect sleeve 47. In this case, when switching from the 4WD-Lo mode to the 2WD-Hi mode, first, the disconnect sleeve 47 is switched from the engaged state to the released state, and then the clutch mechanism 39 is switched to the engaged state. Conversely, when switching from the 2WD-Hi mode to the 4WD-Lo mode, first, after the clutch mechanism 39 is switched to the released state, the disconnect sleeve 47 is switched from the released state to the engaged state. (Mode switching operation by drive mode switching means in the present invention) Hereinafter, a specific description will be given.

<4WD-2WD switching mode>
FIG. 14 is a diagram schematically showing the power transmission device in the 4WD-2WD switching mode during mode switching. As shown in FIG. 14, in the 4WD-2WD switching mode, the clutch mechanism 39 is in a half-engaged state (slip state), and the disconnect sleeve 47 is in a released state (a state in which only the inner engagement plate 45a is engaged). It has become. That is, in the transfer 3, the rotational driving force is transmitted to the ring gear R by limiting the rotation of the sun gear S to some extent so as to obtain a reaction force against the rotation of the carrier CA. In other words, the loss of driving force in the 4WD-2WD switching mode (a state where the driving force is not transmitted to the rear wheels 5L and 5R) is prevented.

  FIG. 16 is a collinear diagram in the 4WD-2WD switching mode. In the 4WD-2WD switching mode, the rotational speed of the motor generator 2 (the rotational speed of the carrier CA) is controlled, and the reaction force obtained by setting the clutch mechanism 39 in a half-engaged state is obtained, whereby the rear wheels 5L and 5R side The driving force is secured.

<Switching operation from 4WD-Lo mode to 2WD-Hi mode>
Next, the switching operation from the 4WD-Lo mode to the 2WD-Hi mode will be specifically described. FIG. 17 is a flowchart showing the procedure of the switching operation from the 4WD-Lo mode to the 2WD-Hi mode. Since the operations in steps ST41 to ST46 in the flowchart shown in FIG. 17 are the same as those in steps ST1 to ST6 in the flowchart shown in FIG. 8 in the first embodiment, description thereof is omitted here.

  If the disconnect sleeve 47 is in the released state and the determination in step ST46 is YES, the process proceeds to step ST47, where the running torque control of the motor generator 2 and the synchronous control of the clutch mechanism 39 are executed. This control adjusts the output torque from the motor generator 2 and the engagement force of the clutch mechanism 39, thereby suppressing the rapid change in torque to the drive wheels, while driving the rear wheels 5L and 5R. This is the control for ensuring the above. Particularly in this case, the engagement force control of the clutch mechanism 39 is mainly performed. In this case, the output torque from the motor generator 2 and the engaging force of the clutch mechanism 39 are mapped in advance to the output torque from the motor generator 2 and the engaging force of the clutch mechanism 39 suitable for the vehicle speed and the like by experiments and simulations. It is stored in the ROM of the ECU 7 and is determined by referring to this map. Further, the output torque from the motor generator 2 may be determined by feedback control according to the differential rotation of the clutch mechanism 39.

  Then, the control of step ST47 is continued until the clutch mechanism rotation difference (difference between the rotation speed of the sun gear S and the rotation speed of the ring gear R that changes according to the engagement force of the clutch mechanism 39) reaches a predetermined value or less. If this clutch mechanism rotation difference reaches a predetermined value or less and YES is determined in step ST48, the process proceeds to step ST49. In this step ST49, the running torque control by the motor generator 2, the synchronous control of the clutch mechanism 39, and the running torque balance control by the clutch mechanism 39 are executed. These controls also adjust the output torque from the motor generator 2 and the engagement force of the clutch mechanism 39, thereby suppressing the sudden change in torque to the drive wheels and driving force to the rear wheels 5L and 5R described above. This is the control for ensuring the above. In particular, in this case, the motor generator 2 is mainly controlled. In this case, the output torque from the motor generator 2 is determined by feedback control corresponding to the differential rotation of the clutch mechanism 39.

  These controls continue until reaching the synchronous rotational speed of the clutch mechanism 39 (the rotational speed at which the clutch mechanism 39 can be completely engaged). When the synchronous rotational speed of the clutch mechanism 39 is reached and YES is determined in step ST50, The process moves to step ST51. In step ST51, an engagement command signal is transmitted to the clutch mechanism 39. As a result, the clutch mechanism 39 operates toward the fully engaged state.

  In step ST52, it is determined whether or not the clutch mechanism 39 is in an engaged state (completely engaged state). If the clutch mechanism 39 is not yet engaged and a NO determination is made in step ST52, an engagement command signal for the clutch mechanism 39 is continuously transmitted (step ST51).

  If the clutch mechanism 39 is in the engaged state and the determination in step ST52 is YES, the process proceeds to step ST53, and the running torque control of the motor generator 2 is executed. In this running torque control, the motor generator 2 is controlled such that a required torque determined according to the accelerator opening detected by the accelerator opening sensor 65 and the vehicle speed detected by the vehicle speed sensor 67 is output.

  With the above operation, the switching operation from the 4WD-Lo mode to the 2WD-Hi mode is completed.

<Switching operation from 2WD-Hi mode to 4WD-Lo mode>
Next, the switching operation from the 2WD-Hi mode to the 4WD-Lo mode will be specifically described. FIG. 18 is a flowchart showing the procedure of the switching operation from the 2WD-Hi mode to the 4WD-Lo mode. The operation in step ST61 in the flowchart shown in FIG. 18 is the same as step ST21 in the flowchart shown in FIG. 9 in the first embodiment, and the operation in step ST62 is shown in FIG. 8 in the first embodiment. It is the same as step ST2 of the flowchart, and the operation of step ST63 is the same as step ST47 of the flowchart shown in FIG. For this reason, explanation here is omitted.

  In step ST64, it is determined whether or not the left-right rotation difference between the front wheels 4L, 4R is equal to or less than a predetermined value. If these rotational differences exceed a predetermined value, the control of the motor generator 2 and the clutch mechanism 39 in step ST63 is continued.

  If the rotational difference is not more than the predetermined value and YES is determined in step ST64, the process proceeds to step ST65. In this step ST65, running torque control by the motor generator 2 and synchronous control of the clutch mechanism 39 and running torque balance control by the clutch mechanism 39 are executed. These controls are performed in the same manner as step ST49 of the flowchart shown in FIG.

  Thereafter, in step ST66, it is determined whether the left and right rotational speeds of the front wheels 4L, 4R are synchronized (substantially coincide). If these rotational speeds are not synchronized, the control of the motor generator 2 and the clutch mechanism 39 in step ST65 is continued.

  If the rotational speed is synchronized and the determination in step ST66 is YES, the process proceeds to step ST67. In step ST67, torque reduction control of the motor generator 2 is executed. This torque-down control is performed in the same manner as step ST3 of the flowchart shown in FIG.

  In step ST68, it is determined whether or not the torque of the motor generator 2 (motor torque) has decreased below a predetermined value. If it has not yet decreased below the predetermined value, a NO determination is made at step ST68, and torque down control is continued until the torque of the motor generator 2 decreases below the predetermined value (step ST67). This predetermined value is set in advance by experiment or simulation, and is set as a value at which the disconnecting sleeve 47 can be easily engaged.

  If the torque of the motor generator 2 falls below a predetermined value and a YES determination is made in step ST68, the process proceeds to step ST69, and an engagement command signal for the disconnect sleeve 47 is transmitted to the disconnect sleeve actuator 48. . As a result, the disconnect sleeve actuator 48 operates, and the disconnect sleeve 47 slides from the released state toward the engaged state.

  In step ST70, it is determined whether or not the disconnect sleeve 47 is engaged. That is, it is determined whether or not the amount of slide movement of the disconnect sleeve 47 has reached the amount of engagement with the outer engagement plate 45b.

  If the disconnect sleeve 47 is not yet engaged and the determination is NO in step ST70, the engagement command signal for the disconnect sleeve actuator 48 is continuously transmitted (step ST69).

  If the disconnect sleeve 47 is in an engaged state and a YES determination is made in step ST70, the process proceeds to step ST71, and the running torque control of the motor generator 2 is executed. In this running torque control, the motor generator 2 is controlled such that a required torque determined according to the accelerator opening detected by the accelerator opening sensor 65 and the vehicle speed detected by the vehicle speed sensor 67 is output.

  With the above operation, the switching operation from the 2WD-Hi mode to the 4WD-Lo mode is completed.

  Even in the present embodiment, the 4WD-Lo mode and the 2WD-Hi mode can be switched according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. That is, the switching function between the four-wheel driving state and the two-wheel driving state and the switching function between the high speed range and the low speed range can be made compatible by one mechanism. For this reason, it is not necessary to dispose the power distribution mechanism and the sub-transmission as separate mechanisms, and as a result, it is possible to simplify the configuration and reduce the size. In addition, the manufacturing cost can be reduced with the simplification of the configuration.

  Further, in the present embodiment, in the 4WD-2WD switching mode, the rotational force is transmitted to the ring gear R so that the clutch mechanism 39 restricts the rotation of the sun gear S so as to obtain a reaction force against the rotation of the carrier CA. To be. That is, it is possible to prevent the driving force from being lost (a state where the driving force is not transmitted to the rear wheels 5L and 5R). For this reason, it is possible to ensure good running performance even in the 4WD-2WD switching mode.

(Fourth embodiment)
Next, a fourth embodiment will be described. In this embodiment, the case where the power transmission device according to the present invention is applied to a four-wheel drive vehicle based on a rear wheel drive will be described. Further, the power transmission device in the present embodiment is different from that in the first embodiment in the configuration of the transfer 3. Therefore, also in the present embodiment, differences from the first embodiment will be mainly described.

  FIG. 19 is a diagram schematically showing a power transmission device 1 for a four-wheel drive vehicle according to the present embodiment. As shown in FIG. 19, the transfer 3 of the power transmission device 1 according to the present embodiment includes a double pinion type planetary gear mechanism 30.

  The planetary gear mechanism 30 of the transfer 3 of the power transmission device 1 according to the present embodiment includes a sun gear S that is an external gear, a ring gear R that is an internal gear arranged concentrically with the sun gear S, and the sun gear S. A plurality of inner pinion gears P1 meshing with each other, a plurality of outer pinion gears P2 meshing with the inner pinion gears P1 and the ring gear R, and a carrier CA that holds the plurality of pinion gears P1 and P2 so as to rotate and revolve. The ring gear R and the carrier CA are used as rotating elements (first to third rotating elements) to perform a differential action. In the present embodiment, the ring gear R is the second rotating element referred to in the present invention, the carrier CA is the first rotating element referred to in the present invention, and the sun gear S is the third rotating element referred to in the present invention.

  An output shaft 26 of the motor generator 2 is connected to the ring gear (second rotating element) R of the planetary gear mechanism 30 so as to rotate together. In addition, a cylindrical sleeve member (cylindrical member) 31 through which the rear propeller shaft 51 is inserted is connected to the carrier (first rotating element) CA of the planetary gear mechanism 30 so as to rotate together. The rear propeller shaft 51 is connected to the sun gear (third rotating element) S of the planetary gear mechanism 30 so as to rotate integrally.

  Other configurations are substantially the same as those of the first embodiment described above. In the present embodiment, the two-wheel drive piece 33, the lock piece 34, and the lock sleeve 35 are disposed on the rear side of the vehicle body with respect to the planetary gear mechanism 30.

-Vehicle driving mode-
Next, a travel mode of the vehicle (four-wheel drive vehicle) in the present embodiment will be described.

  The four-wheel drive vehicle according to the present embodiment switches between the traveling state in the 4WD-Lo mode and the traveling state in the 2WD-Hi mode according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. It is possible. This will be specifically described below.

<4WD-Lo mode>
FIG. 19 shows a traveling state in the 4WD-Lo mode. In the 4WD-Lo mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in an engaged state (engaged with both the engaging plates 45a and 45b). State). That is, in the transfer 3, the carrier CA can rotate relative to the ring gear R, and the rotational driving force from the motor generator 2 is distributed from the ring gear R to the carrier CA and the sun gear S. Therefore, the rotational driving force from the motor generator 2 input to the ring gear R is transmitted to the rear wheels 5L and 5R via the sun gear S, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The Further, the rotational driving force from the motor generator 2 input to the ring gear R includes the carrier CA, the sleeve member 31, the drive sprocket 32, the chain 43, the driven sprocket 42, the front propeller shaft 41, the front differential gear 44, and each front drive shaft. It is transmitted to the front wheels 4L and 4R via 45L and 45R. As a result, traveling in the 4WD-Lo mode is performed.

  FIG. 20 is a collinear diagram in the traveling state in the 4WD-Lo mode. In this alignment chart, the vertical axis represents the rotation speed, and the length of each arrow represents the magnitude of the torque. Further, in order from the left side in the figure, the rotation speed of the sun gear S (matches the rotation speed of the rear propeller shaft 51: rear output), the rotation speed of the ring gear R (matches the rotation speed of the output shaft 26 of the motor generator 2: input), right side The rotation speed of the front wheel 4R (right front output), the rotation speed of the carrier CA (matches the rotation speed of the front propeller shaft 41: front output), and the rotation speed of the left front wheel 4L (left front output). In the figure, ρ is a gear ratio between the sun gear S and the ring gear R, and the output torque TIN of the motor generator 2 is such that the torque of “ρ TIN” is applied to the carrier CA (front output) in the sun gear S (rear output). ) Is given a torque of “(1-ρ) TIN”. In addition, an arrow indicated by a broken line in the figure indicates a torque given to the left and right front wheels 4L and 4R by distributing the torque “(1-ρ) TIN” given to the carrier CA (front output). The arrow shown with a dashed-dotted line has shown the reaction force which acts on carrier CA (front output).

  In this way, the rear propeller shaft 51 (rear output) and the front propeller shaft 41 (front output) rotate at a rotational speed approximately equal to the rotational speed (NIN) of the motor generator 2, and the front and rear wheels 4L, 4R, 5L, 5R. Is a four-wheel drive state in which all of these are drive wheels, and a traveling state in a low speed mode (a mode in which the rotation speed of the motor generator 2 is output without increasing).

<2WD-Hi mode>
FIG. 23 shows a traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, the locking sleeve 35 is in an engaged state (a state in which both the locking piece 34 and the two-wheel drive piece 33 are engaged), and the disconnect sleeve 47 of the disconnect mechanism 46 is in a released state ( The state is engaged only with the inner engagement plate 45a). That is, in the transfer 3, the carrier CA is fixed to the vehicle body side and cannot rotate, and the rotational driving force from the motor generator 2 is transmitted from the ring gear R to the sun gear S. At this time, since the carrier CA is fixed to the vehicle body side, a reaction force against the rotation of the sun gear S is obtained, and the rotational driving force is effectively transmitted to the sun gear S. Therefore, the rotational driving force from the motor generator 2 input to the ring gear R is transmitted to the rear wheels 5L and 5R via the sun gear S, the rear propeller shaft 51, the rear differential gear 52, and the rear drive shafts 53L and 53R. The Further, since the carrier CA is fixed, the rotational driving force is not transmitted to the front propeller shaft 41 side, and the front wheels 4L and 4R are not driving wheels. In this case, the disconnect sleeve 47 is in a released state, and the front differential gear 44 and the right front wheel 4R are separated. For this reason, each front wheel 4L, 4R rotates in the traveling direction (forward direction) as the vehicle travels. Further, as the carrier CA is fixed and the rotation of the front propeller shaft 41 is stopped, the rotation of the differential case 44a of the front differential gear 44 is also stopped. In this case, in the front differential gear 44, the side gears 44d and 44d rotate in opposite directions. That is, the inner front drive shaft 45Ra of the front drive shaft 45R rotates in the direction opposite to the rotation direction of the front wheels 4L and 4R. Thereby, traveling in the 2WD-Hi mode is performed.

  FIG. 24 is an alignment chart in the traveling state in the 2WD-Hi mode. In the 2WD-Hi mode, since the carrier CA is fixed, the rotation speed of the front output is “0”. In contrast, the rotational speed NR of the sun gear S (rear output) is higher than the rotational speed NIN of the ring gear R (input). That is, a speed increasing function is exhibited in which the rotation speed (rear output rotation speed) of the sun gear S is higher than the rotation speed (input rotation speed) of the motor generator 2. In this way, the rear propeller shaft 51 rotates while increasing the rotational speed N R of the sun gear S relative to the rotational speed N IN of the motor generator 2 (while increasing the speed), and the two-wheel drive using the rear wheels 5L and 5R as the driving wheels. In the high-speed mode.

-Switching operation of the vehicle running state-
Next, the switching operation between the above-described 4WD-Lo mode and 2WD-Hi mode will be described. This switching operation is performed by the operation of the locking sleeve 35 and the disconnect sleeve 47 (the operation of the locking sleeve actuator 36 and the operation of the disconnect sleeve actuator 48). In this case, when switching from the 4WD-Lo mode to the 2WD-Hi mode, the disconnect sleeve 47 is first switched from the engaged state to the released state, and then the locking sleeve 35 is switched from the released state to the engaged state. It will be. Conversely, when switching from the 2WD-Hi mode to the 4WD-Lo mode, first, after the locking sleeve 35 is switched from the engaged state to the released state, the disconnect sleeve 47 is switched from the released state to the engaged state. (The mode switching operation by the drive mode switching means in the present invention). This will be specifically described below.

<4WD-2WD switching mode>
FIG. 21 is a diagram schematically showing the power transmission device in the 4WD-2WD switching mode during mode switching. As shown in FIG. 21, in the 4WD-2WD switching mode, the locking sleeve 35 is in a released state (a state in which only the locking piece 34 is engaged), and the disconnect sleeve 47 is in a released state (inner engagement plate 45a). Only engaged). That is, in the transfer 3, the carrier CA can rotate relative to the ring gear R, and the rotational driving force from the motor generator 2 is distributed from the ring gear R to the sun gear S and the carrier CA.

  FIG. 22 is a collinear diagram in the 4WD-2WD switching mode. In the 4WD-2WD switching mode, at the time of switching to the 2WD-Hi mode, a control for reducing the rotational speed of the motor generator 2 is executed, and the rotational speed (input rotational speed) of the ring gear R is reduced to reduce the carrier. The rotational speed of the CA (front output rotational speed) is decreased toward “0”. That is, the rotational speed of the carrier CA (the front output rotational speed) without decreasing the rotational speed of the sun gear S (rear output) or the left front output rotational speed (actually, it gradually decreases due to the road running resistance). ). Thus, by reducing the rotation speed of the carrier CA, the locking sleeve 35 in the released state can be fitted into the spline of the two-wheel drive piece 33. On the other hand, at the time of switching to the 4WD-Lo mode, control for increasing the rotational speed of the motor generator 2 is executed, and the rotational speed of the carrier CA (front output rotational speed) is increased by increasing the rotational speed (input rotational speed) of the ring gear R. ) Is increased, and the right front output rotational speed (the rotational speed NFR of the inner front drive shaft 45Ra) approaches the left front output rotational speed NFL (which matches the rotational speed of the outer front drive shaft 45Rb). By increasing the right front output rotational speed in this way, the disconnected sleeve 47 in the released state is brought into a state where it can engage with the spline of the outer engagement plate 45b.

  Note that the procedure of these switching operations is substantially the same as that described with reference to the flowcharts of FIGS. 8 and 9 in the above-described first embodiment, and thus the description thereof is omitted here.

  Also in the present embodiment, the 4WD-Lo mode and the 2WD-Hi mode can be switched according to the slide movement positions of the locking sleeve 35 and the disconnect sleeve 47. That is, the switching function between the four-wheel driving state and the two-wheel driving state and the switching function between the high speed range and the low speed range can be made compatible by one mechanism. For this reason, it is not necessary to dispose the power distribution mechanism and the sub-transmission as separate mechanisms, and as a result, it is possible to simplify the configuration and reduce the size. In addition, the manufacturing cost can be reduced with the simplification of the configuration.

-Other embodiments-
Each embodiment described above employs the motor generator 2 as a drive source. The present invention is not limited to this, but for a four-wheel drive vehicle using an internal combustion engine (gasoline engine, diesel engine, or the like) as a drive source, or a hybrid four-wheel drive vehicle using a combination of an internal combustion engine and a motor generator as a drive source. Is applicable.

  Moreover, among each embodiment mentioned above, the single pinion type planetary gear mechanism 30 was employ | adopted in 1st-3rd embodiment, and the double pinion type planetary gear mechanism 30 was employ | adopted in 4th Embodiment. As for proper use of these, the single-pinion type planetary gear mechanism has a gear ratio ρ of “number of ring gear teeth / (number of sun gear teeth + number of ring gear teeth)”, and the gear ratio ρ is set to around “0.5”. This is applied when the torques on the front wheel side and the rear wheel side are unevenly distributed. On the other hand, the double pinion type planetary gear mechanism has a gear ratio ρ of “the number of teeth of the sun gear / the number of teeth of the ring gear”, and is therefore applied when the torques are equally distributed to the front wheel side and the rear wheel side.

  The present invention can be applied to a configuration for simplifying and downsizing the configuration of a four-wheel drive vehicle that can switch between a 2WD-Hi mode and a 4WD-Lo mode.

1 Power transmission device 2 Motor generator (drive source)
3 Transfer 30 Planetary gear mechanism 4L, 4R Front wheel (main drive wheel, sub drive wheel)
5L, 5R Rear wheel (Main drive wheel, Sub drive wheel)
R ring gear (first rotating element, second rotating element)
CA carrier (second rotating element, first rotating element)
S Sun gear (third rotating element)
33 Two-wheel drive piece 34 Locking piece 35 Locking sleeve (rotation stop means)
44 Front differential gear (differential mechanism)
45a, 45b engagement plate 46 disconnect mechanism (engagement means)
47 Disconnect sleeve 52 Rear differential gear (differential mechanism)

Claims (7)

A two-wheel drive state in which the driving force from the driving source can be distributed to the main driving wheel and the auxiliary driving wheel, and the driving force from the driving source is not transmitted to the auxiliary driving wheel but only to the main driving wheel, and from the driving source. In a power transmission device for a four-wheel drive vehicle configured to be switchable between a four-wheel drive state that transmits the driving force of both to the main drive wheel and the sub drive wheel,
The planetary gear mechanism disposed on the driving force transmission path that transmits the driving force from the driving source includes three rotating elements, a first rotating element, a second rotating element, and a third rotating element,
The driving source is connected to the second rotating element, the main driving wheel is connected to one rotating element of the first rotating element and the third rotating element, and the auxiliary driving wheel is connected to the other rotating element. And a rotation stop means that is switchable between an engagement state in which the other rotation element is in a rotation stop state and a release state in which the rotation of the other rotation element is allowed,
Between the other rotating element and the sub drive wheel, there is disposed engagement means that can be switched between an engagement state for transmitting torque and a release state for blocking torque transmission,
When the rotation stop means is in the released state and the engagement means is in the engaged state, the four-wheel drive state is entered, while the rotation stop means is in the engaged state and the engagement means is in the released state. In this case, the four-wheel drive is characterized in that the one rotation element connected to the main drive wheel is in a two-wheel drive state in which the rotation speed is increased with respect to the second rotation element. Power transmission device for driving car. The power transmission device for a four-wheel drive vehicle according to claim 1,
The planetary gear mechanism is a single pinion type planetary gear mechanism,
The power transmission device for a four-wheel drive vehicle, wherein the first rotating element is a ring gear, the second rotating element is a planetary carrier, and the third rotating element is a sun gear. The power transmission device for a four-wheel drive vehicle according to claim 1,
The planetary gear mechanism is a double pinion type planetary gear mechanism,
The power transmission device for a four-wheel drive vehicle, wherein the first rotating element is a planetary carrier, the second rotating element is a ring gear, and the third rotating element is a sun gear. The power transmission device for a four-wheel drive vehicle according to claim 1,
The power transmission device for a four-wheel drive vehicle, wherein the engaging means is provided between a differential mechanism that allows the differential of the left and right auxiliary drive wheels and one of the auxiliary drive wheels. The power transmission device for a four-wheel drive vehicle according to claim 1,
4. A power transmission device for a four-wheel drive vehicle, wherein at least one of the rotation stop means and the engagement means comprises a multi-plate clutch. In the power transmission device for a four-wheel drive vehicle according to any one of claims 1 to 5,
In the four-wheel drive state, after the engagement means is completely released, the rotation stop means is completely engaged to switch to a two-wheel drive state. In the two-wheel drive state, after the rotation stop means is completely released, A power transmission device for a four-wheel drive vehicle, comprising drive mode switching means for switching to a four-wheel drive state by completely engaging the engagement means. The power transmission device for a four-wheel drive vehicle according to claim 1, wherein the power transmission method for the four-wheel drive vehicle enables switching between a four-wheel drive state and a two-wheel drive state.
When switching from the traveling state in the four-wheel drive state to the traveling state in the two-wheel drive state, after completely releasing the engagement means, the rotation stop means is completely engaged,
When switching from the traveling state in the two-wheel driving state to the traveling state in the four-wheel driving state, the rotation stopping means is completely released, and then the engaging means is completely engaged. Power transmission method.

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