JP4144586B2 - Transaxle hybrid vehicle - Google Patents

Description

  The present invention relates to a transaxle hybrid vehicle in which an engine is disposed on the front side of a vehicle and a transmission thereof is disposed on the rear side of the vehicle.

  As a vehicle powertrain system, a transaxle system in which an engine is disposed on the front side of the vehicle and a transmission is disposed on the rear side of the vehicle is known. This method has the advantage that the rear axle load increases, so that the slip limit of the rear wheel, which is the drive wheel, increases, and the driving force that can be transmitted to the road surface increases.

  By the way, in a vehicle with an emphasis on power performance, the driving force from a driving force source such as an engine becomes large. Therefore, even in a transaxle system that is advantageous for driving force transmission, the driving wheel is likely to slip in the two-wheel drive. . For this reason, in order to maximize the performance of the vehicle, it is desirable to distribute the driving force to all four wheels.

  However, in the transaxle system, since the transmission is arranged on the rear side of the vehicle, a long propeller shaft extending from the rear side of the vehicle to the front side of the vehicle is required to transmit the driving force from the transmission to the front wheels. Increase in manufacturing cost, manufacturing cost and layout deterioration.

In this regard, Patent Document 1 proposes a system in which a low gear that transmits driving force from the output end of the torque converter to the front wheels is provided, and four-wheel drive is realized only at the time of start acceleration.
JP-A-6-107005

  According to the method disclosed in Patent Document 1, it is possible to transmit the driving force from the engine to the front wheels and the rear wheels and realize four-wheel driving at the time of starting acceleration, so that the driving force transmitted to the road surface is large. Thus, it is possible to effectively suppress the slip of the driving wheel at the time of starting acceleration.

  However, in this method, the four-wheel drive can be realized only at the time of start acceleration, and the four-wheel drive is required at the time of medium-high speed driving and low-μ road driving that require four-wheel driving to improve the running stability of the vehicle. There was a problem that the drive could not be realized.

  The present invention has been made in view of such technical problems, and in a hybrid vehicle of a transaxle system, the mechanism for distributing the driving force of the engine to the front wheels is miniaturized, and also at times other than when starting acceleration. The object is to realize four-wheel drive and to improve the running stability of the vehicle.

A first aspect of the present invention includes an engine and a front wheel disposed on the front side of the vehicle, an engine output shaft connected to the engine, an engine transmission disposed on the rear side of the vehicle and connected to the engine output shaft. A rear wheel disposed on the rear side of the vehicle, to which the driving force of the engine is transmitted via the engine output shaft and the engine transmission, a first motor generator, and at least first to third shafts A differential mechanism, a second motor generator for transmitting a driving force to the rear wheels, and a battery connected to the first and second motor generators, for powering the first motor generator. The first motor generator, the engine output shaft, and the front wheels are arranged on the first to third shafts so that the driving force of the engine distributed to the front wheels increases. When the vehicle is moving forward, the distribution of the driving force of the engine to the front wheels and the rear wheels is changed by controlling the torque of the first motor generator, and power is supplied from the battery to the first motor generator. To distribute the driving force of the engine to the front wheels while supplying electric power from the battery to the second motor generator and driving the rear wheels by the second motor generator, Is supplied to the first motor generator preferentially over the second motor generator, and the remaining electric power is supplied to the second motor generator.
  According to a second aspect of the present invention, there is provided an engine and a front wheel disposed on a front side of a vehicle, an engine output shaft connected to the engine, an engine transmission disposed on a rear side of the vehicle and connected to the engine output shaft. A rear wheel disposed on the rear side of the vehicle, to which the driving force of the engine is transmitted via the engine output shaft and the engine transmission, a first motor generator, and at least first to fourth shafts. Having a differential mechanism, wherein the first motor generator, the engine output shaft, and the front wheels are connected to the first to third shafts, respectively, and the torque of the first motor generator is increased when the vehicle moves forward. A switching mechanism that changes the distribution of the driving force of the engine to the front wheels and the rear wheels by controlling and switches the shaft connected to the front wheels from the third shaft to the fourth shaft; It is a hybrid vehicle, wherein the door.

According to the first aspect of the present invention, the motor generator, the engine output shaft, and the front wheels are arranged on the first to third shafts so that when the first motor generator is powered, the driving force of the engine distributed to the front wheels increases. Thus, the driving force of the motor generator is added to the driving force transmitted to the front wheels and the rear wheels during four-wheel drive, and the power source of the vehicle can be used effectively.
  In addition to the first motor generator, the second motor generator that can transmit the driving force to the rear wheels is provided, so that the power generated by the second motor generator can be supplied to the first motor generator. Even if the battery power is not used, the second motor generator can be powered to distribute the driving force of the engine to the front wheels, thereby realizing a four-wheel drive state.
  In addition, power is supplied from the battery to the first motor generator to distribute the driving force of the engine to the front wheels, while power is supplied from the battery to the second motor generator to drive the rear wheels by the second motor generator. In this case, the electric power from the battery is preferentially supplied to the first motor generator 17 over the second motor generator, and the remaining electric power is supplied to the motor generator. As a result, it is possible to avoid the situation where the power supply to the first motor generator is insufficient and the four-wheel drive state cannot be maintained, and it is possible to distribute the driving force while maintaining the stable driving state by the four-wheel drive. become.
  According to the second aspect of the present invention, the differential mechanism is a differential mechanism having at least first to fourth shafts, and the switching mechanism for switching the shaft to which the front wheels are connected from the third shaft to the fourth shaft. By providing the above, it becomes possible to switch the front wheel gear stage between the low gear state and the high gear state.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

First Embodiment FIG. 1 shows a schematic configuration of a hybrid vehicle according to a first embodiment of the present invention.

  In the hybrid vehicle according to the present invention, a hybrid system that distributes engine driving force to the front wheels using a power transmission mechanism that includes a differential mechanism and a motor generator is used to distribute engine driving force to the front wheels. The mechanism is downsized to achieve both the original weight balance of the transaxle and the hybrid function.

  The engine 11 is an internal combustion engine such as a gasoline engine or a diesel engine, and is disposed on the front side of the vehicle. The motor generator 17 is a three-phase AC motor or the like, and can switch between a power generation state and a power running state. A battery 19 is connected to the motor generator 17 via an inverter 19. The battery 19 supplies power to the motor generator 17, accepts charging, and the like.

  The engine transmission 12 disposed on the rear side of the vehicle is a stepped transmission having a plurality of shift stages. The engine transmission 12 shifts the rotation of the engine 11 transmitted via the engine output shaft 31 and transmits it to the rear wheel 14 via the rear wheel differential 13.

  The planetary gear 20 includes a ring gear 21, a plurality of pinions 24 that mesh with the ring gear 21, a sun gear 23 that meshes with the plurality of pinions 24, and a carrier 22 that rotatably supports the plurality of pinions 24. The planetary gear 20 constitutes a three-axis differential mechanism, the motor generator 17 is connected to the sun gear 23 that is the first shaft, the engine output shaft 31 is connected to the ring gear 21 that is the second shaft, The front wheel 16 is connected to the carrier 22 which is the third shaft via a front wheel drive shaft 32 and a front wheel differential 15.

  The controller 50 is an integrated controller that controls the entire hybrid system. The controller 50 receives the rotational speeds of the front wheels 16 and rear wheels 14 detected by the wheel speed sensors 51 and 52, the operation amount of the accelerator pedal detected by the accelerator operation amount sensor 53, and the like as signals indicating the driving state. . Based on these input signals, the controller 50 controls the torque of the engine 11, the torque and rotational speed of the motor generator 17, the gear stage of the engine transmission 12, and the like, and the driving force of the engine 11 is applied to the front wheels 16 as necessary. Will also be allocated to achieve four-wheel drive.

  Here, the number of teeth of the sun gear 23 of the planetary gear 20 is Zs, the number of teeth of the ring gear 21 is Zr, and the ratio of the number of teeth of the sun gear 23 and the ring gear 21 is

If defined, the relationship between the rotational speed and torque of the three axes of the planetary gear 20 is as follows.

  The subscript r represents the ring gear 21, c represents the carrier 22, and s represents the sun gear 23.

  Furthermore, the relationship of the driving force is expressed by equations (2) and (3):

Thus, the driving force of the sun gear 23 and the driving force of the ring gear 21 are added to obtain the driving force of the carrier 22.

  In FIG. 1, the sun gear 23 is connected to the motor generator 17, and the ring gear 21 is connected to the engine output shaft 31 that is the output shaft of the engine 11. Accordingly, when the motor generator 17 and the engine output shaft 31 have the same rotational direction, the driving forces of the motor generator 17 and the engine 11 are combined and transmitted from the carrier 22 to the front wheels 16 and switched from rear wheel driving to four wheel driving. It is done.

  Since the torque of the engine 11 flowing into the ring gear 21 is determined in proportion to the torque of the motor generator 17 flowing into the sun gear 23 from the equation (3), the front-rear distribution of the driving force is the torque of the engine 11 and the torque of the motor generator 17. It can be changed by adjusting. Further, since the distribution is changed by powering the motor generator 17 instead of generating power, the torque of the motor generator 17 is added to the torque of the engine 11 distributed to the front and rear wheels.

  FIG. 2 shows the control contents of the controller 50 when the accelerator pedal is depressed from the state where the vehicle is running with two-wheel drive to switch to the state where the vehicle is accelerated with four-wheel drive.

  According to this, first, in step S11, the torque of the engine 11 is increased in accordance with the torque command value corresponding to the accelerator operation amount (driver's acceleration request).

  In step S12, it is determined whether or not four-wheel drive is necessary. Whether or not four-wheel drive is necessary is determined in consideration of a driving force request value, a vehicle speed, a steering angle, a yaw rate, a front-rear wheel speed difference, an outside air temperature, information from a navigation system, and the like. If four-wheel drive is necessary, the process proceeds to step S13, and if not necessary, the process is terminated.

  In step S13, the torque of the motor generator 17 is increased. If the torque of the first motor generator 17 is increased, the driving force of the engine 11 distributed to the front wheels 16 is increased to be in a four-wheel drive state, and the torques of the engine 11 and the motor generator 17 are transmitted to the front wheels 16. Can do.

  Therefore, in the hybrid vehicle according to the present invention, the planetary gear 20 as the differential mechanism having the first to third three axes is combined with the transaxle type vehicle, and the motor is applied to the first to third axes of the planetary gear 20. The generator 17, the engine output shaft 31, and the front wheels 16 are connected to each other so that when the vehicle moves forward, the torque of the motor generator 17 is controlled so that the distribution of the driving force of the engine 11 to the front wheels 16 and the rear wheels 14 is changed. As a result, although it is a transaxle vehicle, the driving force of the engine 11 and the driving force of the motor generator 17 can be transmitted to the front wheels 16 in the entire speed range without using a plurality of propeller shafts, thereby realizing four-wheel drive. Further, since the power transmission mechanism to the front wheels 16 has a simple configuration including the motor generator 17 and the differential mechanism, the power transmission mechanism to the front wheels 16 is downsized, and the optimum weight distribution, which is an advantage of the transaxle system, is impaired. There is nothing.

  Further, since the motor generator 17, the engine output shaft 31, and the front wheel 16 are connected to the first to third shafts so that the driving force of the engine 11 distributed to the front wheels 16 increases when the motor generator 17 is powered, During four-wheel drive, the driving force of the motor generator 17 is added to the driving force transmitted to the front wheels 16 and the rear wheels 14, and the power source of the vehicle can be used effectively.

Second Embodiment FIG. 3 shows a second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the following description, differences from the first embodiment will be mainly described.

  In the second embodiment, a second motor generator 61 connected to the engine transmission 12 is added to the configuration of FIG. The second motor generator 61 can transmit the driving force to the rear wheel 13 and can absorb the driving force of the engine 11 transmitted through the engine output shaft 31 by power generation. The second motor generator 61 is connected to the same battery 19 as the first motor generator 17 via the second inverter 62.

  Further, a front wheel speed stage 40 is added to the output end of the carrier 22 of the planetary gear 20. The front wheel speed stage 40 has a low gear 41 and a high gear 42. Switching from the low gear 41 to the high gear 42 is performed at a timing when the rotation speed of the first motor generator 17 increases to a predetermined rotation. Here, the low gear 41 and the high gear 42 are connected to the carrier 22 by the first clutch 46 and the second clutch 47 which are multi-plate clutches in order to reduce the torque fluctuation of the front wheels at the time of switching the front wheel speed. Other clutches such as an electromagnetic clutch and a dog clutch may be substituted.

  FIG. 4 shows the relationship between the vehicle speed and the rotational speed of the first motor generator 17. The solid line shows the first embodiment without the front wheel speed stage 40, and the broken line shows the first speed with the front wheel speed stage 40. It is a thing of 2 embodiment. The front wheel distribution driving force in both cases at zero vehicle speed is set equal.

  As shown in the figure, in the configuration of the first embodiment that does not have the front wheel gear stage 40, the rotational speed of the first motor generator 17 increases as the vehicle speed increases. For this reason, in the first embodiment, it is necessary to make the first motor generator 17 compatible with high-speed rotation. On the other hand, in the configuration of the second embodiment having the front wheel speed stage 40, the rotation range of the motor generator 17 to be used can be narrowed by switching the low gear 41 and the high gear 42.

  As a result, in the configuration of the second embodiment in which the front wheel speed stage 40 is added, the performance required for the first motor generator 17 can be lowered as compared with the configuration of the first embodiment, and a low-cost system can be obtained. Is possible.

  FIG. 5 shows the relationship between the shift timing of the engine transmission 12 and the front wheel speed stage 40 and the rotational speed of the first motor generator 17.

  The case where the low gear 41 and the high gear 42 of the front wheel speed stage 40 are switched asynchronously with the engine transmission 12 will be described. As shown by the alternate long and short dash line in the figure, when the switching timing of the front wheel speed stage 40 is late, that is, the engine transmission 12 When switching is performed at a higher vehicle speed than the speed change point, the rotation speed of the first motor generator 17 increases and overspeeds until the speed is changed from the speed change point of the engine transmission 12 to the high gear 42.

  Conversely, as indicated by the dotted line in the figure, when the switching timing is early, that is, when switching is performed at a lower vehicle speed than the shift point of the engine transmission 12, the rotation direction of the first motor generator 17 is not changed. When the wheel drive state is set, the first motor generator 17 is in a power generation state, and the driving force cannot be added. In this state, when an acceleration command for four-wheel drive is issued, the power generated by the first motor generator 17 needs to be consumed by the second motor generator 61, so that the power of the battery 19 is maximized. Acceleration performance declines without being used.

  Therefore, in the hybrid vehicle according to the present invention, the front wheel speed stage 40 is switched from the low gear to the high gear in synchronization with the engine transmission 12 as indicated by the solid line in the figure. By switching at this timing, problems such as over-rotation do not occur, and stable running performance can be obtained.

  FIG. 6 is a flowchart showing the control contents of the controller 50 when switching the gear position of the front wheel gear stage 40 in the four-wheel drive state in the system of FIG. Executed when is issued.

  Here, in order to switch the front wheel gear stage 40 from the low gear 41 to the high gear 42, it is necessary to switch the first clutch 46 and the second clutch 47. However, depending on the traveling state of the vehicle, the difference in rotational speed between the input side and the output side of the second clutch 47 is large, and shifting may be prolonged or a shock may occur only by changing the clutch. Therefore, when changing the clutch, the first motor generator 17 is used to match the rotational speeds of the two.

  First, in step S21, a gear change command is also issued to the engine transmission 12 in response to the gear change command being issued to the front wheel gear stage 40. This is because, as described above, the low gear and the high gear of the front wheel speed stage 40 are switched in synchronization with the engine transmission 12 so that problems such as over-rotation of the first motor generator 17 do not occur.

  In step S22, the torque of the first motor generator 17 is estimated from the current value of the first motor generator 17, and the front wheel drive torque is estimated based on this. The current value of the first motor generator 17 can be obtained from the command value output from the controller 50 to the inverter 18. As represented by Expression (3), the front wheel drive torque is proportional to the torque of the first motor generator 17, and therefore the front wheel drive torque can be estimated from the torque of the first motor generator 17.

  In step S23, the fastening force of the first clutch 46 is reduced. When the fastening force of the first clutch 46 is reduced, the rotational speed restraint state of the planetary gear 20 is released, and the first motor generator 17 can easily change the rotational state of each element.

  In step S24, the engaging force of the first clutch 46 is decreased and the engaging force of the second clutch 47 is increased, and the first clutch 46 and the second clutch 47 are started to be switched. Since the drive torque transmission path to the front wheels 16 is the first clutch 46 and the second clutch 47, the sum of the fastening forces of these clutches 46 and 47 becomes the front wheel transmission force. Therefore, the engagement force of both clutches is controlled so that the sum of the engagement forces of the clutches 46 and 47 becomes a force equivalent to the front wheel drive torque estimated in step S22.

  In step S25, the speed of the first motor generator 17 is controlled to control the rotational speed of the carrier 22, that is, the input side rotational speed of the second clutch 47, and thereby the rotational speeds of the input side and output side of the clutch 47 are controlled. Move closer. Specifically, the current output side rotational speed of the second clutch 47 is calculated from the rotational speed of the front wheels 16 and the reduction ratio of the high gear 42. Then, the target rotational speed of the first motor generator 17 is set so that the rotational speed of the carrier 22 becomes the output side rotational speed of the second clutch 47, and the first motor is set so as to become the set target rotational speed. The rotational speed of the generator 17 is controlled.

  In step S26, the torque of the engine 11 and the second motor generator 61 is controlled based on the accelerator operation amount, that is, the acceleration request from the driver.

  In step S27, the actual rotational speed of the first motor generator 17 and the target rotational speed are compared, and if the rotational speed difference between the two is below, the process proceeds to step S28. The threshold value is set to a rotational speed difference at which a change in driving force due to a change in inertia does not cause an acceleration greater than 0.05G even when the clutch 47 is instantaneously engaged. This corresponds to a range in which the driver does not feel uncomfortable due to a shock at the time of clutch engagement.

  In step S28, the first clutch 46 is completely disengaged and the second clutch 47 is completely engaged to complete the clutch switching.

  In step S29, the first motor generator 17 is switched from speed control to torque control. The target value at this time is set according to the required front-rear distribution of the driving force and the required driving force.

  According to the above switching control, the change of the shift speed of the front wheel shift stage 40 is performed while suppressing the fluctuation of the front wheel driving force and the fluctuation of the driving force at the time of clutch switching, so that the front wheel shift speed is not generated without causing a shift shock. Forty gears can be changed.

  FIG. 7 is a flowchart showing the contents of the control of the controller 50 when the two-wheel drive is changed to the four-wheel drive according to the traveling state. This flow is executed when the driver depresses the accelerator pedal and an acceleration request is issued.

  In step S31, the torque of the engine 11 is increased in accordance with the torque command value corresponding to the accelerator operation amount (driver acceleration request).

  In step S32, it is determined whether or not four-wheel drive is necessary. Whether or not four-wheel drive is necessary is determined in consideration of the driving force requirement value, vehicle speed, rudder angle, yaw rate, front and rear wheel speed difference, outside air temperature, information from the navigation system, and the like. If four-wheel drive is necessary, the process proceeds to step S33, and if not necessary, the process is terminated.

  In step S33, the torque of the first motor generator 17 is increased. If the torque of the first motor generator 17 is increased, the driving force of the engine 11 distributed to the front wheels 16 is increased to set the four-wheel drive state, and the torques of the engine 11 and the first motor generator 17 are applied to the front wheels 16. Can communicate.

  In step S34, it is determined whether the required driving force according to the accelerator operation amount is insufficient for the assist of the first motor generator 17. If sufficient, the process proceeds to step S36, and if insufficient, the process proceeds to step S35.

  In step S <b> 35, electric power is supplied from the battery 19 to the second motor generator 61, and the second motor generator 61 is powered. By driving the second motor generator 61 and assisting the driving force, it is possible to satisfy the driving force required by the driver while maintaining the four-wheel driving state. At this time, in order to maintain the four-wheel drive state, the first motor generator 17 needs to be in the power running state, so that the power supply from the battery 19 has priority over the power supply to the first motor generator 17. Then, the remaining electric power is supplied to the second motor generator 61.

  In step S36, it is determined whether or not the rear wheel 14 is in a slip state. Whether or not the vehicle is in the slip state can be determined by obtaining the slip ratio from the rotational speed of the rear wheel 14. When the rear wheel 14 is in the slip state (the slip ratio is equal to or greater than a predetermined value), the process proceeds to step S37, and the driving force of the engine 11 that distributes the power distribution of the first motor generator 17 and the motor generator 61 to the front wheel 16 is large. Then, the process returns to step S35 to reduce the driving force assist amount by the motor generator 61.

  Therefore, according to the acceleration control, when the four-wheel drive is required, the driving force of the engine 11 can be distributed to the front wheels 16 to realize the four-wheel drive, and the engine 11 and the first motor can be realized. When the required driving force cannot be realized only by the driving force of the generator 17, the driving force of the rear motor 14 can be assisted by the driving force of the second motor generator 61.

  Further, when the rear wheel 14 slips, the driving force assist amount by the second motor generator 61 is reduced and the driving force of the engine 11 distributed to the front wheel 16 is increased, so that the slip is promptly performed. It can also be converged.

  FIG. 8 is a flowchart showing the control contents of the controller 50 during cruising in the four-wheel drive state. This flow is executed when a four-wheel drive cruise request is issued from the driver.

  Since the cruise in the four-wheel drive state is continuously performed, if the state where power is supplied from the battery 19 continues for a long time, the charged state of the battery 19 becomes zero. Therefore, the power balance of the motor generators 17 and 18 is controlled by the torque control of the motor generators 17 and 18 so that the power supply from the battery 19 is minimized. Here, a case where a four-wheel drive request is issued while the required drive force is constant will be described.

  First, in step S41, the torque of the engine 11 is gradually reduced. This is because in the hybrid vehicle drive device of the present invention, the first motor generator 17 is in the assist state to realize the four-wheel drive state, and therefore the first motor generator 17 is driven by the engine 11 in the four-wheel drive state. This is because the required driving force becomes larger than the actual driving force. Therefore, the torque of the engine 11 whose response performance is slower than that of the first motor generator 17 is first reduced.

  In step S42, the torque of the first motor generator 17 is increased to enter the four-wheel drive state. The actual driving force at this time is equal to the required driving force.

  In step S <b> 43, the electric power consumed by the first motor generator 17 is generated by the second motor generator 61 as the torque of the first motor generator 17 increases.

  In step S44, the driving force of the engine 11 is increased in accordance with the increase in the power generation torque of the second motor generator 61.

  In step S45, it is determined whether the power supplied from the battery 19 is equal to or less than a threshold value. When the power supply from the battery 19 continues, the amount of charge of the battery 19 decreases, so that the power supplied from the battery 19 to the motor generator 17 is controlled to be substantially zero in the cruise state.

  If the supplied power exceeds the threshold value, the process returns to step S43, and the power generation torque of the second motor generator 61 is controlled so that the drive current does not flow from the battery 19 to the first motor generator 17. If the power generation torque of the second motor generator 61 is increased and the generated power is supplied to the first motor generator 17, the drive current from the battery 19 can be reduced. At the same time, by increasing the torque of the engine 11 as the power generation torque of the second motor generator 61 increases, the change in the vehicle driving force is suppressed. At this time, by setting the power generation torque response according to the torque response of the engine 11, control can be performed without giving the driver a sense of incongruity. Since various electric loads are connected to the battery 19, a minute charging state by the second motor generator 61 is desirable in the cruising state.

  Therefore, according to this control, the power supplied from the battery 19 can be lowered below the threshold value in the four-wheel cruise state, and the state of charge of the battery 19 is reduced to zero even if the four-wheel cruise state is continued. Can be prevented.

  In the second embodiment, in addition to the functions and effects of the first embodiment, the following functions and effects are provided.

  In addition to the first motor generator 17, the second motor generator 61 that can transmit the driving force to the rear wheels 14 is provided, so that the electric power generated by the second motor generator 61 is supplied to the first motor generator 17. If supplied, the second motor generator 17 can be powered up without using the electric power of the battery 19 to distribute the driving force of the engine 11 to the front wheels 16, and a four-wheel drive state can be realized. In the configuration shown in FIG. 3, the second motor generator 61 is connected between the engine transmission 12 and the rear wheel differential 13. However, if the driving force can be transmitted to the rear wheel 14, other connection modes, for example, A configuration in which the second motor generator 61 is connected to the engine 1 or the engine output shaft 31 may be employed, or a configuration in which the second motor generator 61 is directly coupled to the rear wheel 14 may be employed.

  Further, power is supplied from the battery 19 to the first motor generator 17 to distribute the driving force of the engine 11 to the front wheels 16, while power is supplied from the battery 19 to the second motor generator 61 to supply the second motor. When the rear wheel 14 is driven by the generator 61, the power from the battery 19 is supplied to the motor generator 17 with priority over the motor generator 61, and the remaining power is supplied to the motor generator 61. As a result, it is possible to avoid a situation in which the power supplied to the first motor generator 17 is insufficient and the four-wheel drive state cannot be maintained, and the driving force distribution can be performed while maintaining a stable traveling state by the four-wheel drive. It becomes possible.

  In addition, since the front wheel speed stage 40 having at least two speed stages is provided between the carrier 22 as the third shaft of the planetary gear 20 and the front wheels 16, the rotation region in which the first motor generator 17 is used is reduced. The required performance can be reduced by narrowing, and the first motor generator 17 can be reduced in size and cost.

  In addition, by synchronizing the shift timing of the engine transmission 12 and the shift timing of the front wheel gear stage 40, the first motor generator 17 is prevented from over-rotating and the like, and the first motor is provided without giving the driver a sense of incongruity. The operating point of the generator 17 can be changed.

  Clutchs 46 and 47 are provided between the third gear (carrier 22) of the planetary gear 20 and the two gears (low gear 41 and high gear 42) of the front wheel gear 40, respectively. Is switched from the torque of the first motor generator 17 to estimate the driving torque distributed to the front wheels 16 and is equivalent to the driving torque distributed to the front wheels 16 where the sum of the fastening forces of the two clutches 46 and 47 is estimated. By switching the clutches 46 and 47 so as to obtain a force, fluctuations in the front wheel driving force during switching can be reduced, and smooth switching can be realized.

  Further, when the clutches 46 and 47 are switched, the first clutch 46 is reduced in engagement force, and then the first clutch 46 is reduced so that the difference in rotational speed between the input side and the output side of the second clutch 47 is reduced. By controlling the speed of the motor generator 17, it is possible to suppress a shock at the time of switching, and it is not necessary to gradually engage the clutch in order to suppress the shock at the time of clutch engagement. It can also be shortened.

  Further, since the output of the engine 11 is increased when the power supplied from the battery 19 to the motor generators 17 and 61 exceeds a predetermined value, the power carried out from the battery 19 can be suppressed to a predetermined value or less. It can be prevented that the power of the battery 19 continues to be consumed and becomes empty.

Third Embodiment FIG. 9 shows a third embodiment of the present invention. The same components as those in the first and second embodiments are denoted by the same reference numerals and description thereof will be omitted. In the following description, differences from the first and second embodiments will be mainly described.

  The third embodiment is different from the second embodiment in that the functions of the planetary gear 20 and the gear stage 40 in the second embodiment shown in FIG. 3 are realized by the Ravigneaux planetary gear 120. The Ravigneaux planetary gear 120 is configured by combining a single pinion planetary gear and a double pinion planetary gear, and includes a first sun gear 121, a common carrier 122, a common ring gear 123, and a second sun gear 124. .

  The Ravigneaux planetary gear 120 is a four-axis differential mechanism, the first sun gear 121 as the first axis is connected to the first motor generator 17, and the ring gear 123 as the second axis is the engine output shaft 31. Connected to. The carrier 122 that is the third shaft and the second sun gear 124 that is the fourth shaft are respectively connected to the front wheel output shaft 33 via the first clutch 141 and the second clutch 142 and the front wheel 16 via the front wheel drive shaft 32. Connected to.

  FIG. 10 is a collinear diagram showing the rotational speed relationship of each element of the Ravigneaux type planetary gear 120. The Ravigneaux planetary gear 120 has four input / output shafts of two sun gears 121 and 124, a carrier 122, and a ring gear 124 as described above.

  Here, assuming that the number of teeth of the first sun gear 121 is Zs1, the number of teeth of the second sun gear 124 is Zs2, and the number of teeth of the ring gear 123 is Zr, the characteristic values ρs and ρd of the Ravigneaux planetary gear 120 are as follows: Define.

  Furthermore, when Zs1, Zs2, and Zr in equation (5) are replaced with coefficients α and β on the nomograph,

It becomes.

  A driving force transmission state of the engine 11 and the first motor generator 17 to the front wheels 16 when the first clutch 141 and the second clutch 142 are engaged will be described using the relationship of Expression (6).

  The low gear state is realized by engaging the first clutch 141 and connecting the carrier 122 to the front wheel 16. At this time, the Ravigneaux planetary gear 120 is in a single pinion state, and the rotational speed and torque between the rotating elements have the following relationship.

  Subscripts c, s1, and r represent the carrier 122, the first sun gear 121, and the ring gear 123, respectively.

  On the other hand, the high gear state is realized by engaging the second clutch 142 and connecting the second sun gear 124 to the front wheel 16. Since carrier 122 is shared, torque of engine 11 and first motor generator 17 is transmitted to front wheel 16 via sun gear 124. The rotational speed and torque between the rotating elements in this state are as follows.

  The subscript s2 indicates the second sun gear 124.

  Since ρs is 0.5 or more due to the establishment condition of the planetary gear, β is 1 or more. Therefore, the torque amplification factor of the first motor generator 17 to the second sun gear 124 that is the output end is smaller in the equation (10) than in the equation (8), and the high gear is achieved by engaging the second clutch 142. It turns out that it will be in a state.

  It should be noted that the power of the first motor generator 17 is added to the engine 11 and transmitted to the front wheels 16 in either the low gear state or the high gear state, so that the first motor generator 17 is connected to the engine output shaft in the high gear state. Rotate in the direction opposite to 31.

  FIG. 11 shows the relationship between the rotational speed of each element in the Ravigneaux type planetary gear 120 and the vehicle speed.

  The rotational speed of the front wheels 16 increases at a constant change rate as the vehicle speed increases. The rotational speed of the first motor generator 17 is reversed before and after the low gear and high gear switching points.

  As described above, in the configuration using the Ravigneaux planetary gear, the power of the first motor generator 17 can be added to the front wheels when the rotation direction of the first motor generator 17 is reversed after the high gear is changed. Therefore, the Ravigneaux planetary gear 120 is designed so that the first motor generator 17 is reversed after the high gear is changed, and the first motor generator 17 is not over-rotated at the highest speed.

  FIG. 12 is a flowchart showing the contents of the front wheel shift stage switching control in the four-wheel drive state. This flow is executed when a shift command for the front wheel gear is issued in response to an increase in vehicle speed or the like from the controller 50.

  In order to shift from the low gear state to the high gear state, it is necessary to switch from the first clutch 141 to the second clutch 142. However, in the state of the vehicle, the rotational speed difference between the input side and the output side of the second clutch 142, that is, the rotational speed difference between the second sun gear 124 and the front wheel output shaft 33 is large. Longer periods or shocks may occur. Therefore, in this control, as described below, the rotational speed of the first motor generator 17 is controlled to reduce the rotational speed difference between the second sun gear 124 and the front wheel output shaft 33 when the clutch is switched.

  First, in step S51, a shift command is issued to the engine transmission 12. This is in order to prevent problems such as over-rotation of the first motor generator 17 by switching between the low gear and the high gear of the front wheel gear stage in synchronization with the engine transmission 12.

  In step S52, the torque of the first motor generator 17 is estimated from the current value of the first motor generator 17, and the front wheel drive torque is estimated based on this. Since the front wheel drive torque is proportional to the torque of the first motor generator 17 from the equation (8), the front wheel drive torque can be estimated from the torque of the first motor generator 17.

  In step S53, the fastening force of the first clutch 141 is reduced. When the fastening force of the first clutch 141 is reduced, the rotational speed restraint state of the Ravigneaux planetary gear 120 is released, and the rotational state of each element is easily changed by the first motor generator 17.

  In step S54, switching control of the first clutch 141 and the second clutch 142 is performed. Since the drive torque transmission path to the front wheels 16 is the first clutch 141 and the second clutch 142, the sum of the fastening forces of these clutches 141 and 142 becomes the front wheel transmission force. Therefore, here, control is performed so that the sum of the engagement forces of the clutches 141 and 142 becomes a force equivalent to the front wheel drive torque estimated in step S52.

  In step S55, the speed of the first motor generator 17 is controlled. The target value tNmg at that time is defined as follows from the target rotational speed tNeng of the engine 11 and the actual value rNs1 of the front wheel rotational speed.

  By this speed control, the rotational speed of the carrier 122 is separated from the rotational speed of the front wheel output shaft 33, and the rotational speed of the second sun gear 124 is brought close to the rotational speed of the front wheel output shaft 33.

  In step S56, the torque of the engine 11 and the second motor generator 61 is controlled based on the accelerator operation amount, that is, the acceleration request from the driver.

  In step S57, it is compared whether the rotation speed of the first motor generator 17 substantially matches the target value tNmg set in step S55. If the difference from the target value is within the threshold value, the process proceeds to the next step S58. The threshold value is set to a rotational speed difference at which a change in driving force due to a change in inertia does not cause an acceleration greater than 0.05 G even when the second clutch 142 is instantaneously engaged. This corresponds to a range in which the driver does not feel uncomfortable due to a shock at the time of clutch engagement.

  In step S58, the first clutch 141 is completely released and the second clutch 142 is completely engaged, and the clutch switching is finished.

  In step S59, the first motor generator 17 is switched from speed control to torque control. The target value at this time is set according to the required front-rear distribution of the driving force and the required driving force.

  According to the switching control described above, the shift control of the front wheel shift stage is performed while changing the shift stage while suppressing the torque at the time of clutch switching while suppressing the fluctuation of the front wheel drive torque, so that the shift stage does not occur. Changes can be terminated.

  Note that the control content of the controller 50 during four-wheel acceleration and four-wheel cruise in the third embodiment is the same as that in the second embodiment shown in FIGS.

  According to the third embodiment, in addition to the functions and effects of the first and second embodiments, the power transmission mechanism on the front wheel side is configured by the Ravigneaux planetary gear 120, so that the power transmission mechanism on the front wheel side is reduced in size. And weight reduction, and can further enjoy the advantages of the transaxle system.

  FIG. 13 is a partial modification of the third embodiment, and a one-way clutch 150 is added to the configuration shown in FIG.

  One-way clutch 150 is connected to second sun gear 124 and operates when engine 11 is started using motor generator 17. If the Ravigneaux planetary gear 120 is designed so that the rotation direction of the motor generator 17 is reversed between the low gear and the high gear, the rotation direction of the second sun gear 124 does not change in all speed ranges, and thus the one-way clutch 150 is arranged in this way. can do.

  By operating the one-way clutch 150, the Ravigneaux type planetary gear 120 functions as a shift stage, and the torque of the first motor generator 17 is multiplied by (1 + α + β) / β and transmitted to the drive shaft of the engine 11. 11 can be cranked and started.

  Although the embodiment of the present invention has been described above, the above embodiment is not intended to limit the technical scope of the present invention to the configuration. The present invention can be variously modified without departing from the spirit of the present invention.

1 is a schematic configuration diagram of a hybrid vehicle according to the present invention (first embodiment). It is the flowchart which showed the content of four-wheel acceleration control. 2 shows a second embodiment of the present invention. In the figure which showed the relationship between a vehicle speed and the rotational speed of a motor generator, a continuous line shows the thing of 1st Embodiment, and a broken line shows the thing of 2nd Embodiment which added the front-wheel gear stage. It is the figure which showed the relationship between the gear change timing of an engine transmission and a front-wheel gear stage, and the rotational speed of a motor generator. It is the flowchart which showed the contents of the gear position change control of the front wheel gear position. It is the flowchart which showed the content of four-wheel acceleration control. It is the flowchart which showed the content of four-wheel cruise control. 3 shows a third embodiment of the present invention. It is a collinear diagram which shows the rotational speed relationship of each element of a Ravigneaux type planetary gear. It is the figure which showed the relationship between the rotational speed of each element in a Ravigneaux type planetary gear, and a vehicle speed. It is the flowchart which showed the contents of the gear position change control of the front wheel gear position. It is a partial change example of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Engine 12 Engine transmission 14 Rear wheel 16 Front wheel 17 Motor generator (1st motor generator)
19 Battery 21 Ring gear (second shaft)
22 Carrier (third axis)
23 Sungear (first shaft)
20 Planetary gear (differential mechanism)
31 Engine output shaft 40 Front wheel gear stage 41 Low gear 42 High gear 46, 47 Clutch 61 Motor generator (second motor generator)
50 Controller 120 Ravigneaux type planetary gear 121 First sun gear (first shaft)
122 Carrier (third axis)
123 Ring gear (second shaft)
124 Second sun gear (fourth shaft)
141 Clutch 142 Clutch 150 One-way clutch (rotation limiting mechanism)

Claims (11)

An engine and front wheels disposed on the front side of the vehicle;
An engine output shaft connected to the engine;
An engine transmission disposed on the rear side of the vehicle and connected to the engine output shaft;
A rear wheel disposed on the rear side of the vehicle, to which the driving force of the engine is transmitted via the engine output shaft and the engine transmission;
A first motor generator;
A differential mechanism having at least first to third three axes;
A second motor generator for transmitting driving force to the rear wheels;
A battery connected to the first and second motor generators;
With
The first motor generator, the engine output shaft, and the front wheels are arranged on the first to third shafts such that when the first motor generator is powered, the driving force of the engine distributed to the front wheels increases. Are connected, and when the vehicle moves forward, the distribution of the driving force of the engine to the front wheels and the rear wheels is changed by controlling the torque of the first motor generator ,
Electric power is supplied from the battery to the first motor generator to distribute the driving force of the engine to the front wheels, while electric power is supplied from the battery to the second motor generator. When driving the rear wheel, the power from the battery is preferentially supplied to the first motor generator over the second motor generator, and the remaining power is supplied to the second motor generator. A hybrid vehicle characterized by The hybrid vehicle according to claim 1 , further comprising a front wheel shift stage having at least two shift stages between the third shaft and the front wheel. The hybrid vehicle according to claim 2 , wherein a shift timing of the engine transmission and a shift timing of the front wheel gear are synchronized. A clutch is provided between each of the third shaft and the two gear positions,
When the two gears are switched by switching the clutch, the driving torque distributed to the front wheels is estimated from the torque of the first motor generator, and the sum of the engaging forces of the two clutches is estimated. 4. The hybrid vehicle according to claim 3 , wherein the fastening force of the first and second clutches is controlled so as to be a force equivalent to a driving torque distributed to the front wheels. When changing the clutch, after reducing the fastening force of the first clutch, the first motor generator is set so that the rotational speed difference between the input side and the output side of the second clutch is reduced. The hybrid vehicle according to claim 4 , wherein the rotational speed is controlled. An engine and front wheels disposed on the front side of the vehicle;
An engine output shaft connected to the engine;
An engine transmission disposed on the rear side of the vehicle and connected to the engine output shaft;
A rear wheel disposed on the rear side of the vehicle, to which the driving force of the engine is transmitted via the engine output shaft and the engine transmission;
A first motor generator;
A differential mechanism having at least first to fourth axes;
With
The first motor generator, the engine output shaft, and the front wheels are connected to the first to third shafts, respectively, and the driving force of the engine is controlled by controlling the torque of the first motor generator when the vehicle moves forward. Change the distribution to the front wheel and the rear wheel,
Features and to Ruha hybrid vehicle further comprising a switching mechanism for switching the axis connecting the front wheels from the third axis to the fourth axis. The hybrid vehicle according to claim 6 , wherein a shift timing of the engine transmission is synchronized with a timing at which the switching mechanism switches a shaft to which the front wheels are connected. A first clutch is provided between the front wheel and the third shaft, and a second clutch is provided between the front wheel and the fourth shaft;
When switching the clutch and switching the shaft to which the front wheels are connected from the third shaft to the fourth shaft, the driving torque distributed to the front wheels is estimated from the torque of the first motor generator, The fastening force of the first and second clutches is controlled so that the sum of the fastening forces of the two clutches becomes a force corresponding to the estimated driving torque distributed to the estimated front wheels. 7. The hybrid vehicle according to 7 . When changing the clutch, after reducing the fastening force of the first clutch, the first motor generator is set so that the rotational speed difference between the input side and the output side of the second clutch is reduced. The hybrid vehicle according to claim 8 , wherein the rotational speed is controlled. The hybrid vehicle according to claim 1 , wherein when the electric power supplied from the battery to the first and second motor generators exceeds a predetermined value, the output of the engine is increased. The differential mechanism is configured such that at least one of the four shafts of the differential mechanism is a forward rotation shaft that always rotates in the same direction when the vehicle moves forward, and one of the forward rotation shafts the hybrid vehicle according to any one of claims 6 9, characterized in that it comprises a rotation limiting mechanism for limiting the rotational direction of the shaft.

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