JP6400449B2 - Control device for power split type continuously variable transmission - Google Patents

Description

  The present invention relates to a control device for a power split type continuously variable transmission.

  As a transmission mounted on a vehicle such as an automobile, a continuously variable transmission mechanism that continuously changes engine power, a gear mechanism that transmits engine power without going through a continuously variable transmission mechanism, and a continuously variable transmission mechanism There has been proposed a planetary gear mechanism for synthesizing the power from the gear and the power from the gear mechanism. In this transmission, the power from the engine can be divided into a continuously variable transmission mechanism and a gear mechanism, and the divided powers can be combined by the planetary gear mechanism and transmitted to the wheels.

JP 2004-176890 A

  The applicant has also proposed a transmission capable of dividing and transmitting the power of the drive source into two systems as a power split type continuously variable transmission.

  The power split type continuously variable transmission according to the proposal includes a continuously variable transmission mechanism that continuously changes power by changing a transmission ratio, a constant transmission mechanism that changes power at a constant transmission ratio, and a continuously variable transmission mechanism. And a synthesizing gear mechanism including a planetary gear mechanism for synthesizing the power passing through the power and the power passing through the constant speed change mechanism. A secondary shaft of a continuously variable transmission mechanism is connected to the sun gear of the synthesizing gear mechanism. An output shaft is connected to the ring gear of the synthesizing gear mechanism. The rotation of the output shaft is transmitted to the differential gear, and is transmitted from the differential gear to the left and right drive wheels.

  This power split type continuously variable transmission has, as a power transmission mode (transmission mode), a belt mode in which power is transmitted to the synthesizing gear mechanism only through the continuously variable transmission mechanism, and the power is continuously variable and constant. A split mode transmitted to the synthesizing gear mechanism via the speed change mechanism.

  In the belt mode, the sun gear and the ring gear of the synthesizing gear mechanism are directly connected by the clutch, and the carrier of the synthesizing gear mechanism is brought into a free state. Therefore, the sun gear and the ring gear rotate integrally with the power output from the continuously variable transmission mechanism, and the output shaft rotates integrally with the ring gear. Therefore, in the belt mode, the gear ratio of the power split continuously variable transmission matches the gear ratio of the continuously variable transmission mechanism.

  In the split mode, the direct coupling between the sun gear and the ring gear of the synthesizing gear mechanism is released, and the power passing through the constant speed change mechanism is input to the carrier of the synthesizing gear mechanism. Since the gear ratio of the constant speed change mechanism is constant and unchanged, if the rotational speed input to the power split continuously variable transmission is constant, the rotational speed of the carrier is kept constant. Therefore, when the gear ratio of the continuously variable transmission mechanism is increased and the rotational speed of the sun gear is decreased, the rotational speed of the output gear connected to the ring gear and the ring gear increases, and the gear ratio of the power split continuously variable transmission decreases. . Therefore, in the split mode, the gear ratio of the power split type continuously variable transmission is equal to or less than the constant gear ratio (the gear ratio of the constant transmission mechanism).

  Switching between split mode and belt mode is possible when differential rotation occurs between the sun gear and the ring gear (the transmission ratio (pulley ratio) of the continuously variable transmission mechanism and the transmission ratio of the constant transmission mechanism deviate). When performed, slippage of the belt or clutch occurs due to the differential rotation. Therefore, switching between the belt mode and the split mode is performed in a state in which the rotation speed of the sun gear of the synthesizing gear mechanism and the rotation speed of the ring gear substantially coincide.

  However, the transmission ratio of the continuously variable transmission mechanism and the constant transmission mechanism may vary depending on various factors such as a delay in response of the clutch, variations in time required for engagement / disengagement of the clutch, and fluctuations in the hydraulic pressure that controls the transmission ratio of the continuously variable transmission mechanism. Deviation may occur between the gear ratio and belt or clutch slippage may occur. When the belt slips, the frictional resistance between the belt and the pulleys (primary pulley and secondary pulley) may decrease due to abnormal wear of the belt, or the belt may be damaged.

  An object of the present invention is to provide a power split type continuously variable transmission that can prevent a decrease in frictional resistance between a belt and a pulley and damage to the belt caused by slipping of the belt when the belt mode and the split mode are switched. It is to provide a control device.

  In order to achieve the above object, a power split type continuously variable transmission control device according to the present invention is provided in parallel with an input shaft, an output shaft, a primary shaft coupled to the input shaft, and the primary shaft. A secondary shaft, a primary pulley supported by the primary shaft, a secondary pulley supported by the secondary shaft, a belt wound around the primary pulley and the secondary pulley, a carrier that rotatably supports the pinion gear, and a pinion gear, A constant gear for meshing the sun gear coupled with the secondary shaft, the ring gear meshing with the pinion gear, coupled with the output shaft, and shifting the power input to the input shaft at a constant gear ratio and transmitting it to the carrier A belt mode in which the sun gear and the ring gear are directly connected when the carrier is in a freely rotating state, and the sun gear and the ring gear. A control device for controlling a power split type continuously variable transmission configured to be switched to a split mode in which direct connection is released and power passing through a constant speed change mechanism is transmitted to a carrier. A mode switching means for switching between, a heat generation amount estimation means for estimating a heat generation amount caused by slipping of the belt when the belt mode and the split mode are switched, and a heat generation amount estimated by the heat generation amount estimation means is a predetermined value or more. A mode switching prohibiting unit that prohibits switching between the belt mode and the split mode by the mode switching unit.

  According to this configuration, when switching between the belt mode and the split mode, the amount of heat generated due to the slipping of the belt at the time of switching is estimated. When the estimated heat generation amount is equal to or greater than a predetermined value, switching between the belt mode and the split mode is prohibited. As a result, when the belt mode and the split mode are actually switched, the amount of heat generated by the slipping of the belt can be suppressed to less than a predetermined value.

  Therefore, the belt can be prevented from being annealed due to heat generation, and the softening due to the annealing of the belt can be suppressed. As a result, abnormal wear of the belt can be suppressed, and a reduction in frictional resistance between the belt and the pulleys (primary pulley and secondary pulley) can be suppressed. Further, the belt can be prevented from being damaged.

  According to the present invention, the surface of the belt can be prevented from being annealed by heat generation, and the softening due to the annealing of the belt surface can be suppressed. As a result, abnormal wear of the belt can be suppressed, and a decrease in frictional resistance between the belt and the pulley can be suppressed. Further, the belt can be prevented from being damaged.

It is a skeleton figure which shows the structure of the drive system of the vehicle to which the control apparatus which concerns on one Embodiment of this invention is applied. It is a figure which shows the state of the high brake, reverse brake, and low clutch at the time of advance of a vehicle, and reverse drive. It is a figure which shows the relationship between the gear ratio of a continuously variable transmission mechanism, and the gear ratio of a power division type continuously variable transmission. It is a collinear diagram which shows the relationship of the rotation speed of the sun gear of a synthetic | combination gear mechanism, a carrier, and a ring gear. It is a block diagram which shows the principal part of the electrical structure of a vehicle. It is a flowchart which shows the flow of a mode switching prohibition process.

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

<Configuration of drive system>

  FIG. 1 is a skeleton diagram showing a configuration of a drive system of a vehicle 1 to which a control device according to an embodiment of the present invention is applied.

  The vehicle 1 is an automobile that uses an engine (E / G) 2 as a power source. The vehicle 1 is equipped with a torque converter 3 and a power split type continuously variable transmission 4.

  The torque converter 3 includes a torque converter input shaft 11, a torque converter output shaft 12, a pump impeller 13, a turbine runner 14, and a lockup clutch 15. The torque converter input shaft 11 and the torque converter output shaft 12 are provided so as to be rotatable about the same rotational axis as the output shaft 16 of the engine 2 (hereinafter referred to as “E / G output shaft 16”). An E / G output shaft 16 is connected to the torque converter input shaft 11. A torque converter input shaft 11 is connected to the center of the pump impeller 13, and the pump impeller 13 is provided to be rotatable integrally with the torque converter input shaft 11. The torque converter output shaft 12 is connected to the center of the turbine runner 14, and the turbine runner 14 is provided to be rotatable integrally with the torque converter output shaft 12. When the lockup clutch 15 is engaged, the pump impeller 13 and the turbine runner 14 are directly connected, and when the lockup clutch 15 is released, the pump impeller 13 and the turbine runner 14 are separated.

  When power is input from the E / G output shaft 16 to the torque converter input shaft 11 in a state where the lockup clutch 15 is released, the torque converter input shaft 11 and the pump impeller 13 rotate. When the pump impeller 13 rotates, an oil flow from the pump impeller 13 toward the turbine runner 14 is generated. This oil flow is received by the turbine runner 14 and the turbine runner 14 rotates. At this time, the amplifying action of the torque converter 3 occurs, and the turbine runner 14 generates a power larger than the power (torque) input to the torque converter input shaft 11. The power of the turbine runner 14 is output from the torque converter output shaft 12.

  In a state where the lock-up clutch 15 is engaged, when power is input from the E / G output shaft 16 to the torque converter input shaft 11, the torque converter input shaft 11, the pump impeller 13, and the turbine runner 14 rotate together. . The power generated by the rotation of the turbine runner 14 is output from the torque converter output shaft 12.

  The power split type continuously variable transmission 4 transmits the power output from the torque converter 3 to the differential gear 5. The power split type continuously variable transmission 4 includes a T / M input shaft 21, a T / M output shaft 22, a continuously variable transmission mechanism 23, a constant transmission mechanism 24, and a synthesizing gear mechanism 25.

  The torque converter output shaft 12 is connected to the T / M input shaft 21.

  The T / M output shaft 22 is provided in parallel with the T / M input shaft 21.

  The continuously variable transmission mechanism 23 has the same configuration as a known belt-type continuously variable transmission (CVT). Specifically, the continuously variable transmission mechanism 23 is supported by the primary shaft 31 connected to the T / M input shaft 21, the secondary shaft 32 provided in parallel with the primary shaft 31, and the primary shaft 31 so as not to be relatively rotatable. A primary pulley 33, a secondary pulley 34 supported by the secondary shaft 32 so as not to rotate relatively, and a belt 35 wound around the primary pulley 33 and the secondary pulley 34.

  The constant speed change mechanism 24 includes a planetary gear mechanism 41, a split drive gear 42, a split driven gear 43, and an idle gear 44.

  The planetary gear mechanism 41 includes a carrier 45, a sun gear 46, and a ring gear 47. The carrier 45 is supported by the T / M input shaft 21 so as not to be relatively rotatable. The carrier 45 supports a plurality of pinion gears 48 so as to be rotatable. The plurality of pinion gears 48 are arranged on the circumference at intervals. The sun gear 46 is externally fitted to the T / M input shaft 21 so as to be relatively rotatable, and meshes with each pinion gear 48 from the inside in the rotational radial direction of the T / M input shaft 21. The ring gear 47 has an annular shape surrounding the carrier 45, and meshes with each pinion gear 48 from the outside in the rotational radial direction of the T / M input shaft 21.

  The split drive gear 42 is provided so as to be able to rotate integrally with the sun gear 46.

  The split driven gear 43 is provided on the outer periphery of the carrier 51 of the synthesizing gear mechanism 25 described below so as to be able to rotate integrally with the carrier 51.

  The idle gear 44 meshes with the split drive gear 42 and the split driven gear 43.

  The synthesizing gear mechanism 25 has a configuration of a planetary gear mechanism. That is, the synthesizing gear mechanism 25 includes a carrier 51, a sun gear 52, and a ring gear 53. The secondary shaft 32 of the continuously variable transmission mechanism 23 is inserted into the center of the carrier 51 so as to be relatively rotatable. The carrier 51 rotatably supports a plurality of pinion gears 54. The plurality of pinion gears 54 are arranged on the circumference. The sun gear 52 is supported by the secondary shaft 32 so as not to be relatively rotatable, and meshes with each pinion gear 54 from the inner side in the rotational radial direction of the secondary shaft 32. The ring gear 53 has an annular shape that surrounds the periphery of the carrier 51, and meshes with each pinion gear 54 from the outside in the rotational radial direction of the secondary shaft 32. One end of the T / M output shaft 22 is connected to the center of the ring gear 53, and the ring gear 53 is provided so as to be able to rotate integrally with the T / M output shaft 22. An output gear 55 is supported at the other end of the T / M output shaft 22 so as not to be relatively rotatable.

  The rotation of the output gear 55 is transmitted to the differential gear 5 via the idle gear mechanism 6. The idle gear mechanism 6 includes an idle shaft 61 provided in parallel with the T / M output shaft 22, and a first idle gear 62 and a second idle gear 63 that are supported by the idle shaft 61 so as not to rotate relative to each other. . The first idle gear 62 meshes with the output gear 55. The second idle gear 63 meshes with a ring gear 64 provided in the differential gear 5.

  The power split type continuously variable transmission 4 includes a high brake HB, a reverse brake RB, and a low clutch LC.

  The high brake HB is switched between an engaged state (on) in which the ring gear 47 is braked and a released state (off) in which the ring gear 47 is allowed to rotate.

  The reverse brake RB is switched between an engaged state (on) in which the split drive gear 42 (sun gear 46) is braked and a released state (off) in which the split drive gear 42 is allowed to rotate.

  The low clutch LC is switched between an engaged state (ON) in which the T / M output shaft 22 and the secondary shaft 32 are directly connected, and a released state (OFF) in which the direct connection is released.

<Power transmission mode>

FIG. 2 is a diagram illustrating states of the high brake HB, the reverse brake RB, and the low clutch LC when the vehicle 1 is moving forward and backward. FIG. 3 shows a speed ratio (hereinafter referred to as “belt speed ratio”) γ _{b of the} continuously variable transmission mechanism 23 and a speed ratio (hereinafter referred to as “T / M speed ratio”) γ _{all of the} power split type continuously variable transmission 4. It is a figure which shows the relationship.

  In FIG. 2, “◯” indicates that the high brake HB, the reverse brake RB, and the low clutch LC are engaged.

  The power split type continuously variable transmission 4 has a belt mode and a split mode as power transmission modes when the vehicle 1 moves forward.

  In the belt mode, the high brake HB and the reverse brake RB are released. Then, the low clutch LC is engaged. Thereby, the T / M output shaft 22 and the secondary shaft 32 are directly connected.

The power input to the T / M input shaft 21 is transmitted to the primary shaft 31 of the continuously variable transmission mechanism 23 to rotate the primary shaft 31 and the primary pulley 33. The rotation of the primary pulley 33 is transmitted to the secondary pulley 34 via the belt 35 and rotates the secondary pulley 34 and the secondary shaft 32. Since the low clutch LC is engaged, the T / M output shaft 22 rotates integrally with the secondary shaft 32. Therefore, in the belt mode, as shown in FIG. 3, the T / M transmission ratio γ _all matches the belt transmission ratio γ _b .

  The rotation of the T / M output shaft 22 is transmitted to the ring gear 64 of the differential gear 5 through the output gear 55, the first idle gear 62, the idle shaft 61 and the second idle gear 63. Thereby, the drive shafts 71 and 72 of the vehicle 1 rotate in the forward direction.

  FIG. 4 is a collinear diagram showing the relationship among the rotation speeds of the carrier 51, sun gear 52 and ring gear 53 of the synthesizing gear mechanism 25.

  In the split mode, as shown in FIG. 2, the high brake HB is engaged, and the reverse brake RB and the low clutch LC are released. When the high brake HB is engaged, the ring gear 47 of the constant speed change mechanism 24 is braked. Further, when the low clutch LC is released, the direct connection between the T / M output shaft 22 and the secondary shaft 32 is released.

  The power input to the T / M input shaft 21 is transmitted to the primary shaft 31 of the continuously variable transmission mechanism 23 to rotate the primary shaft 31 and the primary pulley 33. The rotation of the primary pulley 33 is transmitted to the secondary pulley 34 via the belt 35 and rotates the secondary pulley 34 and the secondary shaft 32. As the secondary shaft 32 rotates, the sun gear 52 of the synthesizing gear mechanism 25 rotates.

  Further, since the ring gear 47 of the constant speed change mechanism 24 is braked, the power input to the T / M input shaft 21 causes the carrier 45 of the constant speed change mechanism 24 to revolve and the pinion gear held by the carrier 45. 48 is rotated. As the pinion gear 48 rotates, power is input from the pinion gear 48 to the sun gear 46. As a result, the pinion gear 48 and the split drive gear 42 rotate. The rotation of the split drive gear 42 is transmitted to the split driven gear 43 via the idle gear 44 and rotates the split driven gear 43 and the carrier 51 of the synthesizing gear mechanism 25.

Since the speed ratio γ _g of the constant speed change mechanism 24 is constant and unchanged (fixed), in the split mode, if the power input to the T / M input shaft 21 is constant, the carrier 51 of the synthesizing gear mechanism 25 The rotation is kept at a constant speed. Therefore, when the belt speed ratio γ _b is increased, as shown in FIG. 4, the rotational speed of the sun gear 52 of the synthesizing gear mechanism 25 decreases, so that the ring gear 53 (T / M output shaft 22 of the synthesizing gear mechanism 25). ) Increases the rotation speed. As a result, in the split mode, as shown in FIG. 3, the larger the belt speed ratio γ _{b, the} lower the T / M speed ratio γ _all .

  The rotation of the T / M output shaft 22 is transmitted to the ring gear 64 of the differential gear 5 through the output gear 55, the first idle gear 62, the idle shaft 61 and the second idle gear 63. Thereby, the drive shafts 71 and 72 of the vehicle 1 rotate in the forward direction.

  In the reverse mode for moving the vehicle 1 backward, the high brake HB and the low clutch LC are released. Then, the reverse brake RB is engaged. Thereby, the split drive gear 42 (sun gear 46) is braked. Due to the braking of the split drive gear 42, the idle gear 44 of the constant speed change mechanism 24 becomes non-rotatable, and the split driven gear 43 and the carrier 51 become non-rotatable.

  The power input to the T / M input shaft 21 is transmitted to the primary shaft 31 of the continuously variable transmission mechanism 23 to rotate the primary shaft 31 and the primary pulley 33. The rotation of the primary pulley 33 is transmitted to the secondary pulley 34 via the belt 35 and rotates the secondary pulley 34 and the secondary shaft 32. As the secondary shaft 32 rotates, the sun gear 52 of the synthesizing gear mechanism 25 rotates. Since the carrier 51 cannot rotate, when the sun gear 52 rotates, the ring gear 53 rotates in the opposite direction to the sun gear 52. The rotation direction of the ring gear 53 is opposite to the rotation direction of the ring gear 53 in the belt mode and the split mode. Then, the T / M output shaft 22 rotates integrally with the ring gear 53. The rotation of the T / M output shaft 22 is transmitted to the ring gear 64 of the differential gear 5 through the output gear 55, the first idle gear 62, the idle shaft 61 and the second idle gear 63. Thereby, the drive shafts 71 and 72 of the vehicle 1 rotate in the reverse direction.

<Electrical configuration>

  FIG. 5 is a block diagram showing a main part of the electrical configuration of the vehicle 1.

  The vehicle 1 is equipped with a plurality of ECUs (electronic control units). Each ECU has a configuration including, for example, a CPU and a memory, and is connected so as to be capable of bidirectional communication using a CAN (Controller Area Network) communication protocol. The plurality of ECUs include an ECU 81 for controlling the drive system.

  The ECU 81 is connected to a primary rotational speed sensor 82, a secondary rotational speed sensor 83, an output rotational speed sensor 84, and a hydraulic pressure sensor 85.

  The primary rotational speed sensor 82 inputs, for example, a pulse signal synchronized with the rotation of the primary pulley 33 of the continuously variable transmission mechanism 23 to the ECU 81. The ECU 81 converts the frequency of the pulse signal input from the primary rotational speed sensor 82 into the rotational speed (primary rotational speed) of the primary shaft 31.

  For example, the secondary rotation speed sensor 83 inputs a pulse signal synchronized with the rotation of the secondary pulley 34 of the continuously variable transmission mechanism 23 to the ECU 81. The ECU 81 converts the frequency of the pulse signal input from the secondary rotational speed sensor 83 into the rotational speed of the secondary shaft 32 (secondary rotational speed).

  The output rotation speed sensor 84 inputs, for example, a pulse signal synchronized with the rotation of the output gear 55 to the ECU 81. The ECU 81 converts the frequency of the pulse signal input from the output rotation speed sensor 84 into the rotation speed (output rotation speed) of the T / M output shaft 22.

  The hydraulic sensor 85 inputs a detection signal corresponding to the hydraulic pressure supplied to the secondary pulley 34 of the continuously variable transmission mechanism 23 to the ECU 81. Specifically, the secondary pulley 34 forms an oil chamber between a fixed sheave fixed to the secondary shaft 32, a movable sheave supported by the secondary shaft 32 so as not to be rotatable relative to the secondary shaft 32, and movable in the axial direction. A sheave spring that biases the cylinder and the movable sheave and the cylinder apart from each other is provided, and the hydraulic pressure supplied to the oil chamber is controlled to apply a clamping pressure to the belt 35. The oil pressure sensor 85 detects the oil pressure supplied to the oil chamber of the secondary pulley 34 and inputs a detection signal corresponding to the oil pressure to the ECU 81.

  Various types of valves (not shown) included in a hydraulic circuit 86 for supplying hydraulic pressure to the power split continuously variable transmission 4 are connected to the ECU 81 as a control target. The valves include, for example, valves that respectively control the hydraulic pressure for engaging / disengaging the high brake HB, reverse brake RB, and low clutch LC of the power split continuously variable transmission 4.

  The ECU 81 switches between the belt mode and the split mode by controlling the valve included in the hydraulic circuit 86 and switching the engagement / release of the high brake HB and the low clutch LC. Switching between the belt mode and the split mode is performed in a state where the transmission ratio of the continuously variable transmission mechanism 23 is within a predetermined switching allowable range. The switching allowable range is set to a predetermined range including the transmission ratio of the constant transmission mechanism 24. The transmission ratio of the constant transmission mechanism 24 is set to the same value as the minimum transmission ratio of the continuously variable transmission mechanism 23, for example.

  Further, the ECU 81 controls a valve included in the hydraulic circuit 86 to switch between engagement / release of the low clutch LC and the reverse brake RB, thereby switching between the forward mode (belt mode) and the reverse mode.

<Mode switching prohibition process>

  FIG. 6 is a flowchart showing the flow of the mode switching prohibiting process.

  When the speed ratio of the continuously variable transmission mechanism 23 is within a predetermined switching allowable range and it is necessary to switch between the belt mode and the split mode, the ECU 81 executes a mode switching prohibiting process shown in FIG.

  In the mode switching prohibiting process, first, an element load F (N) received per element of the belt 35 of the continuously variable transmission mechanism 23 is calculated (step S1).

  The belt 35 is configured by attaching a large number of elements to a hoop (endless annular body) made of an annular metal plate in a state where the elements are connected in the circumferential direction of the hoop. The element load F is obtained by dividing the load f received by the entire belt 35 from the secondary pulley 34 by the number C of elements included in the belt 35.

  The load f multiplies the hydraulic pressure supplied to the oil chamber of the secondary pulley 34 by the area (pressure receiving area) of the portion of the movable sheave of the secondary pulley 34 that receives the hydraulic pressure, and the multiplied value acts on the movable sheave of the secondary pulley 34. This is calculated by adding the centrifugal hydraulic pressure to be applied and the spring force of the sheave spring of the secondary pulley 34. The oil pressure supplied to the oil chamber of the secondary pulley 34 is detected by the oil pressure sensor 85. The pressure receiving area of the movable sheave, the centrifugal hydraulic pressure acting on the movable sheave, and the spring force of the sheave spring are values determined by the configuration of the secondary pulley 34 and are known values.

The number C is calculated by dividing the thickness of the element (dimension in the circumferential direction) by the product of the winding angle of the belt 35 relative to the secondary pulley 34 and the winding diameter (diameter). The element thickness (m) is a known value, and the winding angle (rad) and the winding diameter (m) are values determined by the pulley ratio of the primary pulley 33 and the secondary pulley 34 (belt transmission ratio γ _b ). is there. The pulley ratio can be obtained from the primary rotational speed and the secondary rotational speed. As described above, the primary rotational speed and the secondary rotational speed are acquired from the pulse signals output from the primary rotational speed sensor 82 and the secondary rotational speed sensor 83, respectively.

Next, the slip amount V of the belt 35 generated when the belt mode and the split mode are switched is calculated (step S2). The slip of the belt 35 occurs due to a deviation between the belt speed ratio γ _b and the speed ratio γ _g of the constant speed change mechanism 24. Therefore, the difference between the rotational speed of the secondary pulley 34 obtained by dividing the primary speed in the belt variable speed ratio gamma _b, the rotational speed of the secondary pulley 34 obtained by dividing the primary speed by the gear ratio gamma _g Corresponds to the slip amount V (rpm) of the belt 35.

  Thereafter, the amount of heat generated by the slipping of the belt 35 is estimated using the element load F and the slip amount V calculated in advance (step S3). Specifically, the transmission torque capacity Tr of the continuously variable transmission mechanism 23 is obtained from the element load F, the slip amount V, the time required for switching (engaging / disengaging) the low clutch LC and the high brake HB, and unit conversion. By multiplying the transmission torque capacity Tr by 2π / 60 for this purpose, the amount of heat generated by the slipping of the belt 35 is estimated.

  And it is determined whether the estimated calorific value is more than a predetermined value (Step S4). The predetermined value is set to a value smaller than the amount of heat that causes the belt 35 to be annealed, for example.

  If the estimated heat generation amount is equal to or greater than the predetermined value (YES in step S4), switching between the belt mode and the split mode is prohibited (step S5), and the mode switching prohibiting process is terminated.

  If the estimated heat generation amount is less than the predetermined value (NO in step S4), switching between the belt mode and the split mode is permitted (step S6), and the mode switching prohibiting process is terminated.

<Effect>

  As described above, when switching between the belt mode and the split mode, the amount of heat generated by slipping of the belt 35 at the time of switching is estimated. When the estimated heat generation amount is equal to or greater than a predetermined value, switching between the belt mode and the split mode is prohibited. As a result, when the belt mode and the split mode are actually switched, the amount of heat generated by the slipping of the belt 35 can be suppressed below a predetermined value.

  Therefore, the belt 35 can be prevented from being annealed due to heat generation, and the softening due to the annealing of the belt 35 can be suppressed. As a result, abnormal wear of the belt 35 can be suppressed, and a reduction in frictional resistance between the belt 35 and the primary pulley 33 and the secondary pulley 34 can be suppressed. Further, damage to the belt 35 can be suppressed.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The present invention can be implemented in other forms, and various modifications can be made to the above-described configuration within the scope of the matters described in the claims.

4 power split type continuously variable transmission 21 T / M input shaft 22 T / M output shaft 24 constant transmission mechanism 31 primary shaft 32 secondary shaft 33 primary pulley 34 secondary pulley 35 belt 51 carrier 52 sun gear 53 ring gear 54 pinion gear 81 ECU (control) Device, mode switching means, calorific value estimation means, mode switching prohibition means)

Claims (1)

An input shaft, an output shaft, a primary shaft connected to the input shaft, a secondary shaft provided in parallel with the primary shaft, a primary pulley supported by the primary shaft, and supported by the secondary shaft A secondary pulley, a belt wound around the primary pulley and the secondary pulley, a carrier that rotatably supports a pinion gear, a sun gear that is engaged with the pinion gear and that is connected to the secondary shaft, and a gear that is engaged with the pinion gear A ring gear connected to the output shaft, and a constant speed change mechanism for shifting the power input to the input shaft at a constant speed ratio and transmitting the power to the carrier. A belt mode in which a sun gear and the ring gear are directly connected, and a direct connection between the sun gear and the ring gear. Is divided, there is provided a control device for controlling the constant power transmission mechanism power via is configured to switch to split mode and is transmitted to the carrier split type continuously variable transmission,
Mode switching means for switching between the belt mode and the split mode;
A calorific value estimating means for estimating a calorific value generated by slipping of the belt when switching between the belt mode and the split mode;
A control device, comprising: a mode switching prohibiting unit that prohibits the mode switching unit from switching between the belt mode and the split mode when the heat generation amount estimated by the heat generation amount estimating unit is greater than or equal to a predetermined value.

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