JP7647654B2 - Hybrid vehicle control device - Google Patents

Description

This invention relates to a hybrid vehicle capable of transmitting motor torque to the drive wheels in addition to the engine, and in particular to a control device for a hybrid vehicle capable of maintaining the vehicle in a stopped state by engaging a lock pole with a parking gear, and transmitting torque from the motor to the parking gear when the lock pole is disengaged from the parking gear.

This type of parking device is configured to stop the rotation of the drive wheels by engaging the lock pole with the parking gear connected to the drive wheels, thereby keeping the vehicle stationary. Therefore, if torque is applied to the drive wheels when the vehicle is stopped, a similar torque is also applied to the parking gear, causing the parking gear and lock pole to mesh tightly. In such a case, when attempting to release the parking state by removing the lock pole from the parking gear, the large frictional force between the two acts as a resistance force, requiring a large operating force. Patent Document 1 describes a device that aims to eliminate such inconveniences.

The device described in Patent Document 1 is configured to reduce the force required to disengage the lock pole that is engaged with the parking gear from the parking gear when shifting from the parking position to another position. More specifically, when an intention to shift to a non-parking position is detected, the device is configured to apply torque from the motor to the parking gear in a direction that loosens the engagement between the parking gear and the lock pole, i.e., in a direction that reduces the force required to disengage the lock pole from the parking gear. The direction in which the torque is applied, i.e., the direction in which the parking gear is rotated, is determined based on the tilt direction detected by a tilt angle sensor serving as a load detection means.

Japanese Patent Application Publication No. 9-286312

The parking gear is connected to the drive wheels via a propeller shaft or a drive shaft, and is configured to rotate together with the drive wheels. Therefore, when the vehicle is stopped on an uphill road, a torque corresponding to the vehicle weight and the inclination angle of the road surface is applied to the drive wheels, and this torque is transmitted to the parking gear and becomes the torque that rotates the parking gear. The device described in Patent Document 1 focuses on the fact that such a torque increases the meshing force (engagement force) between the parking gear and the lock pole, and applies a torque counter to this torque to the parking gear by the motor, loosening the meshing between the parking gear and the lock pole. However, the manner of meshing between the parking gear and the lock pole, the causes of the meshing, and even the engagement force are diverse, and if the direction and magnitude of the torque from the motor are determined based on the inclination angle of the road surface, it may be difficult to disengage the lock pole from the parking gear.

For example, if a vehicle stops with a twist in the power transmission system, such as the propeller shaft or drive shaft installed between the parking gear and the drive wheels, and the lock pole engages with the parking gear to stop its rotation, the torque caused by the twist is applied to the parking gear, increasing the engagement force with the lock pole. In this case, the direction and magnitude of the torque applied to the parking gear will be different depending on whether the vehicle is stopped by moving forward on a flat road or moving backward and then stopping, and will also be different depending on whether the parking brake is applied after stopping the vehicle with the foot brake or whether the parking brake is applied before the foot brake is applied. Such differences will also occur when stopping halfway uphill and halfway downhill.

The device described in Patent Document 1 controls the direction and magnitude of the torque from the motor according to the inclination direction and angle of the road surface. Therefore, if the direction of the torque applied to the parking gear (i.e., the direction of meshing between the parking gear and the lock pole) is opposite to the direction caused by the inclination of the road surface due to torque caused by torsion of the power transmission system, the torque from the motor acts in a direction that makes the meshing between the parking gear and the lock pole stronger. Also, when the vehicle is stopped on an inclined road surface and the parking brake is engaged, the parking gear may be in a position (state) where it will not rotate even if torque is applied to release the lock. Even in such a case, the torque from the motor acts in a direction that makes the meshing between the parking gear and the lock pole stronger. In other words, the device in Patent Document 1 does not apply torque from the motor to the parking gear based on the state of meshing between the parking gear and the lock pole, which can make it more difficult to remove the lock pole from the parking gear, or if the lock pole is removed from the parking gear by an actuator, it may be necessary to make the actuator larger, or a large amount of energy may be consumed to release the parking state.

This invention was made with a focus on the above technical problems, and aims to provide a control device that can reliably perform control to reduce the operating force required to disengage the lock pole from the parking gear in a hybrid vehicle equipped with a motor as a driving force source, while also eliminating unnecessary control.

In order to achieve the above object, the present invention provides a hybrid vehicle including drive wheels driven by a motor, a parking gear connected to the drive wheels via a power transmission member and rotating together with the drive wheels, a lock pole that selectively meshes with the parking gear to stop the rotation of the drive wheels together with the parking gear, and an operating member that operates the lock pole in a direction to mesh with the parking gear and a direction to disengage from the parking gear, the hybrid vehicle control device being configured to apply torque to the parking gear by the motor in a direction that reduces the meshing load between the parking gear and the lock pole when the lock pole is engaged with the parking gear, the parking gear is provided with a parking release determination unit which determines that there is a request to release the lock pole from the parking gear, an inspection torque application unit which, when the parking release determination unit determines that there is a request to release the lock pole from the parking gear, applies an inspection torque in the direction of the meshing load estimated from the state of ascending or descending a slope or the state of forward/reverse movement during parking, to the parking gear with the lock pole engaged with the parking gear, by the motor, a behavior determination unit which determines the behavior of the parking gear when the inspection torque is applied to the parking gear, and a load reduction necessity determination unit which determines whether or not control to reduce the meshing load is necessary based on a determination result of the behavior determination unit.

In this invention, when there is a request to disengage the lock pole from the parking gear by shifting from the parking position to another shift position, the parking release determination unit determines that such a request exists. When this determination is made, the motor applies an inspection torque to the parking gear in the direction of the meshing load estimated from the state of ascending or descending a slope or forward/reverse movement during parking . In this case, since the parking gear and the lock pole are engaged, if the direction of the inspection torque is a direction that moves the teeth of the parking gear toward the teeth of the lock pole that are engaged with it (the direction opposite to the backlash side), the rotation of the parking gear is prevented by the lock pole and the parking gear does not rotate. Conversely, if the direction of the inspection torque is a direction that moves the teeth of the parking gear toward the backlash side, the parking gear rotates toward the backlash side (in the direction to reduce the backlash). That is, by applying the inspection torque, the parking gear rotates or does not rotate depending on the state of meshing with the lock pole at that time, and the presence or absence of such rotation, i.e., the behavior, is judged by the behavior judgment unit. If it is judged that the parking gear rotates by applying the inspection torque, it can be estimated that the meshing between the parking gear and the lock pole is loose, and conversely, if it is judged that the parking gear does not rotate, it can be estimated that the meshing between the parking gear and the lock pole is strong. Therefore, based on the result of the judgment by the behavior judgment unit, it is possible to select whether or not to execute control to reduce the meshing load between the parking gear and the lock pole, and as a result, it is possible to reliably reduce the operating force to disengage the lock pole from the parking gear. Also, when the meshing is loose, it is possible not to execute control to reduce the meshing load between the parking gear and the lock pole, so that unnecessary torque control can be eliminated.

1 is a schematic diagram showing an example of a drive system of a hybrid vehicle to which the present invention is applied; FIG. 2 is a partial schematic diagram for explaining the configuration of this parking mechanism. 3 is a flowchart for explaining a control executed in the embodiment of the present invention. 5A and 5B are schematic diagrams showing the meshing state between the teeth of the parking gear and the engaging teeth of the lock pole, where FIG. 5A shows the state when a torsional torque is applied, and FIG. 5B shows the state when no torsional torque is applied. 1A is a time chart showing changes in state, command values, etc. when control according to an embodiment of the present invention is performed, where (A) shows an example when assist control is not performed, and (B) shows an example when assist control is performed.

Next, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is merely one example of how the present invention can be implemented, and is not intended to limit the present invention.

Figure 1 shows a schematic diagram of a driving force transmission system of a hybrid vehicle according to an embodiment of the present invention, and Figure 2 shows a schematic diagram of the parking mechanism. The hybrid vehicle shown here has an engine 1 and two motors (motor generators) 2, 3 as driving force sources, and is configured to split the power of the engine 1 between the output side and the first motor 2 side, generate electricity with the first motor 2, control the engine speed with the first motor 2, and supply the electricity generated by the first motor 2 to the second motor 3, which outputs the driving force for running. In the example shown in Figure 1, a single-pinion type planetary gear mechanism 4 is provided as a mechanism for splitting the power output by the engine 1, and the torque of the engine 1 is input to the carrier 5 of the single-pinion type planetary gear mechanism 4, which serves as an input element. An oil pump 6 is provided between the engine 1 and the planetary gear mechanism 4, and the engine 1 drives the oil pump 6 to obtain hydraulic pressure. The first motor 2 is arranged on the same axis as the engine 1, and its rotor shaft 7 is connected to a sun gear 8, which serves as a reaction element. Furthermore, a ring gear 9 serves as an output element, and an output gear 10 is provided integrally with the ring gear 9. A parking gear (or parking lock gear) 11 is provided integrally with the output gear 10. The output gear 10 and parking gear 11 are externally toothed gears with teeth formed on the outer circumferential surface of a specified cylindrical member.

A counter shaft 12 is provided parallel to the central axis of the first motor 2 and the planetary gear mechanism 4, and a counter driven gear 13 meshing with the output gear 9 is attached to the counter shaft 12. The second motor 3 is arranged parallel to this counter shaft 12, and a motor drive gear 15 attached to its rotor shaft 14 meshes with the counter driven gear 13. In other words, the second motor 3 is configured to add or subtract torque from the torque (sometimes called engine direct torque) output from the planetary gear mechanism 4, which is a power split mechanism.

A counter drive gear 16, which has a smaller diameter than the counter driven gear 13, is attached to the counter shaft 12, and this counter drive gear 16 meshes with a ring gear 18 in a differential gear 17, which is a final reduction gear. The differential gear 17 is configured to output a drive torque for the drive wheels 20 via a drive shaft 19. Therefore, the drive wheels 20 and the parking gear 11 are connected via power transmission members such as the counter driven gear 13, counter shaft 12, differential gear 17, and drive shaft 19, and are configured to rotate together. In other words, by stopping the rotation of the parking gear 11, the rotation of the drive wheels 20 is stopped, and the hybrid vehicle can be maintained in a stopped state.

The parking mechanism 21 is a mechanism that selectively stops the rotation of the parking gear 11 to maintain the hybrid vehicle in a parked state. An example of the parking mechanism 21 will be described with reference to FIG. 2. A lock pole 22 is provided on the outer periphery (more specifically, the lower side) of the parking gear 11. The lock pole 22 is an arm-shaped member arranged in a direction substantially tangential to the parking gear 11, and one end of the lock pole 22 is attached to a predetermined fixed part (not shown) so that it can rotate around an axis parallel to the central axis of the parking gear 11. An engagement tooth 22a that is convex toward the parking gear 11 is provided at the middle part in the longitudinal direction of the lock pole 22 and on the surface facing the parking gear 11. The engagement tooth 22a has a shape corresponding to the teeth 11a of the parking gear 11, and is configured to enter between the teeth 11a of the parking gear 11 and mesh with the teeth 11a of the parking gear 11.

An operating member 23 that operates the lock pole 22 so that the engagement teeth 22a mesh with the teeth 11a of the parking gear 11 is provided on the free end side of the lock pole 22 (the end side opposite to the end supported rotatably). This operating member 23 may be of a conventionally known general structure, and is configured to move a cam 24 arranged on the lower side of the lock pole 22 back and forth between a position on the lower side of the lock pole 22 and a position away from that position. The cam 24 is configured to have a tapered shape, for example, and pushes the free end of the lock pole 22 up toward the parking gear 11 by entering the lower side of the lock pole 22, so that the engagement teeth 22a mesh with the teeth 11a of the parking gear 11. The mechanism that operates the operating member 23 in this way may be a mechanism in which a shift lever provided in a shift device is connected to the operating member 23 by a cable, or an appropriate shift actuator (not shown) that operates under electrical control when the shift lever is operated.

The lock pole 22 is provided with an elastic member such as a torsion coil spring 25 that exerts an elastic force in a direction in which the engagement teeth 22a of the lock pole 22 disengage from the teeth 11a of the parking gear 11. When the cam 24 is retracted from a position below the lock pole 22, this elastic force causes the lock pole 22 to rotate around one end of the lock pole 22, disengaging the engagement teeth 22a from the teeth 11a of the parking gear 11.

Figure 2 shows the parking-locked state with a twist in the power transmission member such as the drive shaft 19 described above. When the drive source such as the engine 1 is outputting torque and the rotation of the drive wheels 20 is stopped by braking or hitting a car stop, the power transmission member such as the drive shaft 19 is twisted. The torsional torque of the power transmission member acts as a reaction force against the torque applied to the drive wheels 20 on the parking gear 11, whose rotation is stopped by meshing with the engagement teeth 22a of the lock pole 22. This torsional torque is indicated by the symbol "T1" in Figure 2.

In addition to the torsional torque T1 described above, the torque acting on the parking gear 11 in the parking lock state includes torque caused by the hybrid vehicle stopping in the middle of an uphill or downhill slope and gravitational acceleration acting in the direction of moving the hybrid vehicle forward or backward. In any case, when torque is acting on the parking gear 11, the surface pressure at the point where the teeth 11a and the engaging teeth 22a are in contact increases, causing a large frictional force, making it difficult to disengage the engagement. To solve this problem, when releasing the parking lock, a so-called assist control is performed in which an assist torque is applied to the parking gear 11 to eliminate or reduce the torque (i.e., the meshing load) acting on the parking gear 11, such as the torsional torque T1.

This assist control may be similar to the control described in the above-mentioned Patent Document 1, and when an intention to change the shift position selected by a shift device (not shown) from the parking position to another shift position is detected, an assist torque is applied to the parking gear 11 by the second motor 3 described above. Specifically, an assist torque is applied in a direction to release the contact between the tooth 11a and the engaging tooth 22a, in other words, in a direction to reduce the backlash. In Figure 2, this assist torque is indicated by the symbol "Ta".

This type of assist control is effective when torque is applied in the direction indicated by the symbol T1 in FIG. 2, but if torsional torque T1 or the like is not applied and the meshing between the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 is in the opposite state to that shown in FIG. 2, the assist torque Ta acts in a direction that strengthens the meshing between the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22, making it more difficult to release the parking lock. In order to prevent such a situation from occurring, the control device that is an embodiment of this invention is equipped with a controller 26 that controls the torque applied to the parking gear 11 from the second motor 3, including the above-mentioned assist control.

The controller 26 is mainly composed of a microcomputer including a calculation element, a storage element, and an interface, and is configured to perform calculations according to a pre-prepared program using data input from an appropriate sensor (not shown) or pre-stored data, and to output the results of the calculations as a control command signal. Examples of the input data include a signal indicating the shift position, a signal detecting that an operation to shift from the parking position to another shift position has been performed or is about to be performed, a signal from a gradient sensor detecting the gradient of the road surface where the hybrid vehicle is stopped, a detection signal for a change in the phase of the parking gear 11, and a signal detecting the release of the lock of the parking gear 11 by the lock pole 22. Examples of pre-stored data include the direction of the assist torque according to the detection signal from the gradient sensor, the magnitude of the assist torque, a predetermined value for determining the change (rotation) in the phase of the parking gear 11, and a target position for rotating the parking gear 11 by the assist control. Then, a signal indicating the torque and rotation direction to be output by the second motor 3 is output as a control command signal.

The control device in this embodiment of the invention is configured to determine whether or not assist control is required prior to the above-mentioned assist control. The functional configuration of the controller 26 for this determination is as follows: the controller 26 is provided with a parking release determination unit 26A that determines whether or not there is a request to release the parking lock, or that such a request has been made. In conventional assist control, the intention to shift from the parking position to another shift position is determined as a condition for executing control to apply an assist torque, and the parking release determination unit 26A may be configured to perform a similar determination. More specifically, the controller 26A may be configured to determine whether or not the parking lock is released by detecting that the driver has touched the shift lever with the foot brake (not shown) depressed, or that the shift lever has been moved from the parking position.

The vehicle also includes an inspection torque application unit 26B that outputs an inspection torque from the second motor 3 to determine the state of meshing between the parking gear 11 and the lock pole 22. The magnitude and direction of the inspection torque can be determined in advance. For example, the direction of the inspection torque can be determined based on the tilt direction of the hybrid vehicle obtained by a gradient sensor or the driving direction immediately before stopping. In addition, the magnitude of the inspection torque should be small enough to rotate the parking gear 11 without the application of torsional torque T1 or the like.

When an assist torque is applied to the parking gear 11 and exceeds the torque applied to the parking gear, the parking gear 11 rotates or the phase shifts. Alternatively, if the assist torque is a torque in a direction that strengthens the engagement between the parking gear 11 and the lock pole 22, the rotation of the parking gear 11 is prevented by the lock pole 22, so there is no change in the phase of the parking gear 11. A behavior determination unit 26C is provided that determines whether or not there is such a change in the phase of the parking gear 11 due to the application of the assist torque, i.e., the behavior.

Then, a load reduction necessity determination unit 26D is provided which determines whether or not to execute assist control based on the determination result of the behavior determination unit 26C. Specifically, if the behavior of the parking gear 11 has changed due to the inspection torque, it is determined that the above-mentioned assist control is unnecessary, and in the opposite case, it is determined that the above-mentioned assist control is necessary.

To explain the control for determining whether such assist control is necessary in more detail, FIG. 3 is a flow chart for explaining an example of such control, which is executed by the controller 26 described above. In the control shown in FIG. 3, first, a shift from the parking position (P) to another position (non-P) (P ⇒ non-P shift) is read (step S1). The functional means for executing this step S1 corresponds to the parking release determination unit in this embodiment of the invention. Next, an actuator (shift actuator) that operates the operating member 23 described above is operated (step S2). The timing of the operation of the shift actuator may be any appropriate timing, such as after the application of the inspection torque or after the assist control.

Next, the direction of the assist torque to be applied to the parking gear 11 is obtained (step S3). This direction is opposite to the direction of the torque assumed to be applied to the parking gear 11 in the parking lock state. In other words, the direction of the torque assumed to be applied to the parking gear 11 is opposite when the hybrid vehicle is stopped on an uphill slope to that when it is stopped on a downhill slope, and is also opposite when the vehicle moves forward and stops with torque remaining to that when it moves backward and stops with torque remaining. In any case, the direction of the torque applied to the parking gear 11 during parking can be estimated from the structure of the drive system.

In obtaining the direction of applying the assist torque, since the direction of the load acting between the parking gear 11 and the lock pole 22 is known, the above-mentioned test torque is applied in the direction in which the load increases (step S4). The functional means for executing the control of step S4 corresponds to the test torque application unit in the embodiment of the present invention. Next, it is determined whether the amount of change in the phase of the parking gear 11 exceeds a predetermined value (step S5). When the hybrid vehicle is stopped in the middle of an uphill or downhill road and the movement of the hybrid vehicle is stopped by the parking mechanism 21, the state of engagement (or meshing state) between the parking gear 11 and the lock pole 22 differs depending on the method or timing of braking when parking lock is performed, so the application of the above-mentioned test torque may change the behavior (phase) of the parking gear 11 or may not change.

Figure 4 shows the situation diagrammatically, and (A) shows a state in which a torsion torque T1 acts on the parking gear 11 due to a torsion occurring in the power transmission member such as the drive shaft 19. Since the inspection torque Td acts in the direction of the meshing load, when a torsion occurs in the power transmission member, the inspection torque Td only strengthens the meshing between the parking gear 11 and the lock pole 22, and does not change the behavior (or phase) of the parking gear 11. In contrast, the state shown in (B) is a state in which no torsion occurs in the power transmission member, and the meshing direction between the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 is opposite to that shown in (A). Therefore, since the inspection torque Td acts in a direction that disengages the teeth 11a and 22a (direction that eliminates backlash), the inspection torque Td rotates the parking gear 11 in a direction that eliminates backlash, causing a change in phase.

In step S5, such a change in the behavior (phase) of the parking gear 11 is detected, and it is determined whether the amount of change is greater than a predetermined value. The change in the phase of the parking gear 11 can be detected by a resolver (not shown) provided on the second motor 3 that outputs the inspection torque Td, or a sensor (not shown) may be provided on the parking gear 11 and used to detect the change.

If the answer at step S5 is positive, the load reduction control execution judgment is set to OFF (step S6). This load reduction control is the assist control described above, and in step S6, a judgment is made that the assist control will not be executed. In other words, if the answer at step S5 is positive, it can be assumed that the meshing between the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 is not particularly strong, so the assist control is not executed. Therefore, in this case, the process returns after confirming or detecting the completion of the release of the parking lock (step S7).

On the other hand, if the result of step S5 is negative, the load reduction control execution judgment is set to ON (step S8). Then, the assist control is executed. Specifically, the target displacement position θ1 is commanded according to the current gear position θ of the parking gear 11 (step S9). These positions θ, θ1 are phases for the parking gear 11 that can be detected by the resolver, and the target displacement position θ1 is the phase at which the parking gear 11 rotates to such an extent that the teeth 11a of the parking gear 11 separate from the engagement teeth 22a of the lock pole 22, and can be determined in advance in design as a value obtained by adding or subtracting a predetermined angle to the current gear position θ. The functional means for executing the control of step S6 and the control of step S8 above corresponds to the load reduction necessity judgment unit in this embodiment of the invention.

Next, the second motor 3 applies an assist torque Ta to the parking gear 11 so that the current gear position θ coincides with the target displacement position θ1 (step S10). It is then determined whether or not the parking lock has been released (step S11). This determination can be made, for example, by detecting the position of the lock pole 22 with an appropriate sensor (not shown). If the determination in step S11 is negative, the control in step S10 (application of assist torque Ta) continues. Conversely, if the determination in step S11 is positive, the process returns.

Therefore, by performing the control according to the embodiment of the present invention shown in FIG. 3, it is possible to avoid performing the assist control unnecessarily, and therefore to prevent unnecessary power consumption by the second motor 3, thereby improving the so-called power consumption in the hybrid vehicle.

Figure 5 shows the changes in state and command values when the above-mentioned control is performed. (A) shows an example when the load reduction control execution judgment is OFF, i.e., assist control is not performed, and (B) shows an example when the load reduction control execution judgment is ON, i.e., assist control is performed.

In FIG. 5A, when there is a request to change the shift position from the parking position (P) to another shift position (non-P) (at time t1), the shift actuator that operates the operating member 23 in the parking mechanism 21 starts to operate, and its torque gradually increases. At the same time, the second motor (MG2) 3 outputs the inspection torque Td described above. As a result, the parking gear 11 rotates in a direction that reduces the backlash, and the position (phase) of the parking gear 11 changes. When a change in the behavior of the parking gear 11 is detected (at time t2), the output of the inspection torque Td is stopped almost simultaneously. In this case, the change in behavior of the parking gear 11 due to the inspection torque Td is detected, and the execution determination (or flag) of the assist control described above is maintained OFF.

Meanwhile, as the shift actuator operates and outputs torque, the cam 24 in the parking mechanism 21 is pulled out from the underside of the lock pole 22, and the operating force pushing the lock pole 22 toward the parking gear 11 is released. As the phase of the parking gear 11 changes due to the inspection torque Td, the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 are no longer engaged, or even if they are engaged, their contact force (engagement force or surface pressure) is reduced. Therefore, as the cam 24 is pulled out, the lock pole 22 rotates clockwise in Figures 2 and 4 due to the elastic force of the torsion coil spring 25, etc. In other words, the parking lock by the lock pole 22 is released, and the shift state becomes a so-called non-parking (non-P) state other than the parking state (time t3). At the same time, the operation of the shift actuator stops, and its torque returns to zero. That is, by determining or detecting the meshing state between the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 using the inspection torque Td, the parking lock can be released and a shift state can be achieved with another shift position without performing assist control by driving the second motor 3. Note that if the hybrid vehicle remains stopped, the parking gear 11 remains in the phase it was in when the parking lock was released, and if the hybrid vehicle is running, it rotates together with the output gear 10.

In contrast, in the case shown in FIG. 5B, when there is a request to change the shift from the parking position (P) to another shift position (non-P) (time t11), the shift actuator that operates the operating member 23 in the parking mechanism 21 starts to operate, and its torque gradually increases. At the same time, the aforementioned inspection torque Td is output from the second motor (MG2) 3. Up to this point, it is the same as the case shown in FIG. 5A described above.

In the example shown in FIG. 5B, a torsional torque is applied to the parking gear 11, and the teeth 11a of the parking gear 11 and the engaging teeth 22a of the lock pole 22 mesh with each other and are in strong contact with each other due to the torsional torque. In addition, the inspection torque Td acts in the same direction as the torsional torque, so the engagement force or contact pressure between the teeth 11a and 22a only increases, and the parking gear 11 does not rotate. In other words, there is no change in the position or behavior of the parking gear 11. As a result, the execution determination (or flag) of the aforementioned assist control is turned ON (at time t12).

When the assist control execution determination is ON, the second motor 3 outputs an assist torque Ta. The assist torque Ta gradually increases at a predetermined gradient. This assist torque acts to reduce the torsional torque T1 applied to the parking gear 11, so as the assist torque Ta increases, the pressure at which the teeth 11a of the parking gear 11 contact the engaging teeth 22a of the lock pole 22 and the frictional force resulting therefrom decrease. When the frictional force thus decreased becomes smaller than the elastic force of the elastic member such as the torsion coil spring 25 that rotates the lock pole 22, the lock pole 22 disengages from the parking gear 11, and the parking gear 11 rotates (the phase changes). Then, when the parking gear 11 rotates to the target position θ1 (at time t13), the output of the assist torque Ta is stopped, the shift actuator stops outputting torque, and the assist control execution determination is returned to OFF. Furthermore, by completely disengaging the lock pole 22 from the parking gear 11, the shift state becomes a so-called non-parking (non-P) state other than the parking state. Only when it is determined that the torsional torque T1 is applied to the parking gear 11 and it is difficult to disengage the lock pole 22, is the assist control executed to output torque from the second motor 3, and the parking lock can be released smoothly or easily. In other words, except in such a case, the assist control to drive the second motor 3 is not executed, so that it is possible to avoid situations such as wasting power by driving the second motor 3 unnecessarily.

The present invention is not limited to the above-described embodiment, and the hybrid vehicle to which the present invention is applied does not have to be the so-called two-motor type hybrid vehicle described above. In short, it is sufficient for the hybrid vehicle to be configured so that the parking gear can be rotated by the driving motor in the parking state.

REFERENCE SIGNS LIST 1 Engine 2 First motor 3 Second motor 4 Planetary gear mechanism 10 Output gear 11 Parking gear 11a Teeth 12 Counter shaft 13 Counter driven gear 14 Rotor shaft 15 Motor drive gear 16 Counter drive gear 17 Differential gear 18 Ring gear 19 Drive shaft 20 Drive wheel 21 Parking mechanism 22 Lock pole 22a Engagement teeth 23 Operation member 24 Cam 25 Torsion coil spring 26 Controller 26A Parking release determination section 26B Inspection torque application section 26C Behavior determination section 26D Load reduction necessity determination section T1 Torsion torque Ta Assist torque Td Inspection torque

Claims (1)

A hybrid vehicle includes a drive wheel driven by a motor, a parking gear connected to the drive wheel via a power transmission member and rotating together with the drive wheel, a lock pole selectively meshing with the parking gear to stop the rotation of the drive wheel together with the parking gear, and an operating member for operating the lock pole in a direction to mesh with the parking gear and a direction to disengage from the parking gear, the hybrid vehicle control device being configured to apply torque to the parking gear by the motor in a direction to reduce an engagement load between the parking gear and the lock pole when the lock pole is meshed with the parking gear,
a parking release determination unit that determines whether there is a request to disengage the lock pole that is engaged with the parking gear from the parking gear;
an inspection torque applying unit that applies, when the parking release determining unit determines that there is a request to disengage the lock pole from the parking gear, an inspection torque in the direction of the meshing load estimated from the state of ascending or descending a slope or the state of forward/reverse movement during parking, to the parking gear with the lock pole engaged with the parking gear by the motor;
a behavior determination unit that determines a behavior of the parking gear when the inspection torque is applied to the parking gear;
a load reduction necessity determining unit that determines whether or not control for reducing the meshing load is necessary based on a determination result of the behavior determining unit.

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