Vehicle control system

Abstract

The present invention provides a vehicle control device that can suppress vibrations and shocks that occur when the parking lock mechanism is released while the drive shaft is twisted. [Solution] The system comprises a drive shaft with one end connected to a wheel, a motor capable of transmitting torque to the drive shaft, and a parking lock mechanism that can selectively switch between a locked state in which the rotation of a predetermined rotating member between the motor and the drive shaft is prohibited and an unlocked state in which the predetermined rotating member is rotatable. When it is predicted that the parking lock mechanism will switch from the locked state to the unlocked state, the system counteracts the estimated torsional torque of the drive shaft and begins outputting a torque from the motor that is less than or equal to the torsional torque (step S4), and stops outputting torque from the motor when the motor that is outputting torque begins to rotate (step S1).

Description

Technical Field

[0001] This invention relates to a vehicle control device capable of locking a drive shaft by a parking lock mechanism.

Background Art

[0002] Patent Document 1 and Patent Document 2 describe a vehicle control device provided with a parking lock mechanism configured to prohibit rotation of a drive shaft connected to a wheel by engaging a parking gear interlocked with the wheel with a parking pole, and to enable the drive shaft to rotate by releasing the engagement.

[0003] In the parking lock mechanism described in Patent Document 1, a shift lever operated by a driver and a parking pole are mechanically connected. Therefore, when the load acting on the meshing surface between the parking gear and the parking pole is large, the operating force of the shift lever required to release the meshing increases. Therefore, the control device described in Patent Document 1 is configured to output torque from a motor in a direction in which the meshing load between the parking lock gear and the parking pole decreases. Specifically, the output torque of the motor is gradually increased, and the meshing load between the parking lock gear and the parking pole is decreased by maintaining the torque at the time when the rotation angle of the motor changes. Further, the control device is configured to decrease the output torque of the motor toward "0" when it is determined that the parking lock mechanism has been released.

[0004] Furthermore, the vehicle described in Patent Document 2 is equipped with a parking lock mechanism, a foot brake device that applies braking force to the wheels when activated by the driver's operation of pressing the brake pedal, and an electric parking brake that operates in conjunction with the parking lock mechanism to continuously apply braking force to the wheels.The control device described in Patent Document 2 is configured such that, when the road surface gradient angle is greater than or equal to a predetermined angle, even if the driver releases their brake pedal operation, braking force will continue to be applied to the wheels by the foot brake device from the time the shift operation to select the parking position is performed until braking force is applied to the wheels by the electric parking brake. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3454009 [Patent Document 2] Japanese Patent Publication No. 2020-100312 [Overview of the project] [Problems that the invention aims to solve]

[0006] The control device described in Patent Document 1 reduces the operating force of the shift lever required to release the parking lock mechanism by outputting torque from the motor until the engagement between the parking lock gear and the parking pawl is disengaged. Furthermore, the control device reduces the output torque of the motor when it is determined that the parking lock mechanism has been released. In other words, the control device described in Patent Document 1 has the motor bear all of the torsional torque of the drive shaft, and reduces the motor's torque when it is determined that the parking lock mechanism has been released.

[0007] Therefore, the control device described in Patent Document 1 requires time to determine that the parking lock mechanism has switched to the released state. As a result, if the braking torque of the wheels is reduced immediately after the parking lock mechanism is released, the vehicle may start moving unintentionally.

[0008] Furthermore, if the motor outputs a torque smaller than what is needed to disengage the parking lock gear and the parking pawl, the torsional torque of the drive shaft is transmitted to the motor and the torque transmission member between the motor and the drive shaft when the parking lock mechanism switches to the released state. This torsional torque decreases while pulsating according to the elastic modulus of the drive shaft. Therefore, if there is a delay in determining that the parking lock mechanism has switched to the released state, as described above, the motor torque will be added to the reversed torsional torque. As a result, it may not be possible to quickly reduce the torsional torque of the drive shaft.

[0009] This invention was made in view of the above-mentioned technical problems, and the object of this invention is to provide a vehicle control device that can suppress the occurrence of vibrations and shocks when the parking lock mechanism is released while the drive shaft is twisted. [Means for solving the problem]

[0010] To achieve the above objective, this invention provides a vehicle control device comprising: a drive shaft with one end connected to a wheel; a motor capable of transmitting torque to the drive shaft; and a parking lock mechanism capable of selectively switching between a locked state in which the rotation of a predetermined rotating member between the motor and the drive shaft is prohibited and an unlocked state in which the predetermined rotating member is rotatable, wherein the device comprises a controller for controlling the motor, the controller comprising: a parking determination unit for determining that the parking lock mechanism is in the locked state; a prediction unit for predicting that the parking lock mechanism will switch from the locked state to the unlocked state; a torsional torque estimation unit for estimating the torsional torque of the drive shaft; a motor control start unit for starting to output a torque from the motor that is equal to or less than the estimated torsional torque of the drive shaft when it is predicted that the parking lock mechanism will switch from the locked state to the unlocked state; and a motor control end unit for ending the output of torque from the motor when the motor that is outputting torque starts to rotate.

[0011] Furthermore, in this invention, the motor control termination unit may terminate the output of torque from the motor when a predetermined time has elapsed since the motor began outputting torque.

[0012] Furthermore, in this invention, the motor control termination unit may terminate outputting torque from the motor when the parking lock mechanism switches from the locked state to the unlocked state.

[0013] Furthermore, this invention further includes a shift device operated by the driver to select a desired driving range from a plurality of driving ranges, including a parking range in which the parking lock mechanism is in the locked state, and the prediction unit may predict that the parking lock mechanism will switch from the locked state to the unlocked state when a shift operation is performed to select another driving range from the parking range in which the parking lock mechanism is in the unlocked state.

[0014] Furthermore, in this invention, the torsional torque estimation unit may estimate the torsional torque of the drive shaft based on the inclination angle in the pitching direction of the vehicle. [Effects of the Invention]

[0015] The vehicle control device in this invention, when it is predicted that the parking lock mechanism will switch from a locked state to an unlocked state, counteracts the estimated torsional torque of the drive shaft and begins outputting a torque from the motor that is less than or equal to the torsional torque. In other words, it outputs a torque from the motor that counteracts the torsional torque even before the parking lock mechanism is released. Therefore, the load acting on the parking lock mechanism 11 can be reduced, and a sudden change in the torque counteracting the drive shaft when the parking lock mechanism is released can be suppressed. As a result, the torque transmitted from the drive shaft to the motor when the parking lock mechanism is released can be reduced. In other words, fluctuations in the rotational speed of the torque transmission part between the motor and the drive shaft can be suppressed, and vibration of the vehicle can be suppressed.

[0016] Furthermore, by ceasing to output torque from the motor as soon as it starts rotating, the motor's torque can be reduced before the direction of the torsional torque reverses. In other words, it is not necessary to determine whether the parking lock mechanism has switched from the locked state to the unlocked state. As a result, the motor's torque can be reduced rapidly, thereby suppressing the increase in vibration caused by the motor's output torque being added to the reversed torsional torque. In other words, it is possible to suppress the decrease in the vibration damping effect of the torque transmission part, including the motor, after the parking lock mechanism is released. That is, vehicle vibrations can be reduced rapidly. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic diagram showing an example of a vehicle according to an embodiment of this invention. [Figure 2] Figure 2 is a block diagram illustrating the functional configuration of the controller. [Figure 3] Figure 3 is a flowchart illustrating an example of control that determines whether or not to output assist torque from the motor. [Figure 4] Figure 4 is a time chart illustrating the changes in driving range, shift position, vehicle tilt angle, motor control execution flag, assist execution counter, and motor rotation speed (absolute value) when the motor rotation speed exceeds a predetermined rotation speed and the motor control execution flag is switched off. [Figure 5] Figure 5 is a time chart illustrating the changes in the driving range, vehicle tilt angle, shift position, motor speed, and motor control execution flag when the motor control execution flag is switched off by setting a driving range other than the parking range. [Figure 6] Figure 6 is a time chart illustrating the changes in the driving range, vehicle tilt angle, motor control execution flag, motor speed, and assist execution counter when the motor control execution flag is switched off due to the assist execution counter being above a predetermined value.

Embodiments for Carrying Out the Invention

[0018] This invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples when this invention is embodied, and do not limit this invention.

[0019] An example of a vehicle in an embodiment of this invention is schematically shown in FIG. 1. The vehicle Ve shown in FIG. 1 is an electric vehicle equipped with a motor (MG) 1 as a driving force source. The motor 1 can be configured in the same manner as the motors provided as driving force sources in conventional electric vehicles and hybrid vehicles. That is, in addition to the function as a motor that generates driving torque by being supplied with electric power from a power storage device (not shown), it has a function as a generator that converts at least a part of the power of the output shaft 2 into electric power when the output shaft 2 is rotated. Specifically, it is constituted by a permanent magnet type synchronous motor, an induction motor, or the like.

[0020] A first drive gear 3 is attached to the output shaft 2 of the motor 1. A first driven gear 4 that meshes with the first drive gear 3 and is formed with a larger diameter than the first drive gear 3 is attached to an intermediate shaft 5 arranged parallel to the output shaft 2 of the motor 1. That is, a reduction gear pair is constituted by the first drive gear 3 and the first driven gear 4.

[0021] A second drive gear 6 is further attached to the intermediate shaft 5. A second driven gear 7 that meshes with the second drive gear 6 and is formed with a larger diameter than the second drive gear 6 is attached to an output shaft 8 arranged parallel to the output shaft 2 of the motor 1 and the intermediate shaft 5. That is, a reduction gear pair is constituted by the second drive gear 6 and the second driven gear 7. One end of a drive shaft 9 is integrally rotatably connected to the output shaft 8, and a wheel 10 is connected to the other end of the drive shaft 9.

[0022] Furthermore, a parking lock mechanism 11 is provided that can selectively switch between a locked state in which the rotation of the intermediate shaft 5 is prohibited and an unlocked state in which the intermediate shaft 5 is rotatable. This parking lock mechanism 11 can be configured in the same way as parking lock mechanisms provided in conventional vehicles. Specifically, the parking lock mechanism 11 consists of a parking lock gear 12 attached to the intermediate shaft 5, a parking pawl 13 that can selectively engage with the parking lock gear 12, and an actuator (not shown) that operates the parking pawl 13. When a parking range is selected by the shift device 24 described later, the parking pawl 13 is rotated by an actuator (not shown) or the like to engage with the parking lock gear 12. By engaging the parking pawl 13 with the parking lock gear 12 in this way, the rotation of the parking lock gear 12 is prohibited. Therefore, the rotation of the drive shaft 9, which is connected to the parking lock gear 12 via the intermediate shaft 5 or the like in a way that allows torque transmission, is prohibited.

[0023] The vehicle Ve shown in Figure 1 is equipped with a brake system 14 that applies braking torque to the wheels 10 in accordance with the amount of operation of a brake pedal (not shown) operated by the driver. This brake system 14 can be configured in the same way as brake systems installed in conventional vehicles. That is, it can be configured as a disc brake that applies braking torque to the wheels 10 by clamping a brake rotor that rotates integrally with the wheels 10 with brake pads, or as a drum brake that applies braking torque to the wheels 10 by pressing brake shoes from the inside of a drum that rotates integrally with the wheels 10. Furthermore, the clamping force of the brake pads and the pressing force of the brake shoes can be controlled by an actuator (not shown) that generates hydraulic or electromagnetic force in accordance with the amount of operation of the brake pedal.

[0024] Furthermore, the vehicle Ve shown in Figure 1 is equipped with an electric parking brake (hereinafter referred to as EPB) 15. This EPB 15 is configured in the same way as an EPB installed in a conventional vehicle, and when a shift operation is performed to select the parking range, the motor 16 is activated, driving a caliper and brake shoe (not shown) to apply braking torque to the wheel 10, and when a driving range other than the parking range is selected, the braking torque is reduced. From the viewpoint of mounting the motor 16, the motor 16 may be installed on the vehicle body, and a wire or the like that is provided to connect the motor 16 to the caliper and brake shoe, and the caliper and brake shoe may be driven by rotating the motor 16 to wind up the wire.

[0025] In the example shown in Figure 1, the motor 1, the gear train that transmits torque from the motor 1 to the output shaft 8, and the torque transmission unit that transmits torque from the motor 1 to the drive shaft 9, such as the output shaft 8, are housed in a single case 17, which is connected to the vehicle body 19 via a mount 18. The wheels 10 are also held to the vehicle body 19 via a suspension 20.

[0026] In the vehicle Ve shown in Figure 1, when the brake pedal is operated and the driver performs a shift operation to select the parking range, the vehicle is permitted to switch the driving range to the parking range. When switching to the parking range in this manner, the rotation of the intermediate shaft 5 is prohibited by the parking lock mechanism 11, and braking torque is applied to the wheels 10 by the EPB 15.

[0027] As described above, the time from when the shift operation is performed until the rotation of the intermediate shaft 5 is prohibited by the parking lock mechanism 11 may be shorter than the time until braking torque is applied to the wheels 10 by the EPB 15. Therefore, for example, when parking the vehicle Ve on a slope or when the wheels 10 are parked on top of some object, if the driver reduces the amount of brake pedal operation before braking torque is applied to the wheels 10 by the EPB 15, the wheels 10 will rotate (turn) even though the rotation on the input side of the drive shaft 9 is prohibited. Also, if the EPB 15 cannot be activated for some reason, the wheels 10 will rotate (turn) even though the rotation on the input side of the drive shaft 9 is prohibited after the driver reduces the amount of brake pedal operation. As a result, the drive shaft 9 twists. In other words, torque (hereinafter referred to as torsional torque) corresponding to its elastic modulus and the amount of twist accumulates in the drive shaft 9.

[0028] The amount of torsion (i.e., torsional torque) of the drive shaft 9 is proportional to the tilt angle of the vehicle Ve. Specifically, the longitudinal load acting on the vehicle Ve, depending on its tilt angle, acts on the contact surface of the wheel 10 with the road surface, and a torque proportional to this load and the radius of the wheel 10 acts on one end of the drive shaft 9. In contrast, the other end of the drive shaft 9 does not rotate because it is locked by the parking lock mechanism 11. As a result, the drive shaft 9 gradually twists, generating a torsional torque proportional to the amount of torsion and the elastic modulus of the drive shaft 9. The amount of torsion of the drive shaft 9 is maintained when the torque acting on the drive shaft 9 from the wheel 10 balances the torsional torque proportional to the amount of torsion of the drive shaft 9. The direction of torsion of the drive shaft 9 corresponds to the tilt direction in the pitching direction of the vehicle Ve.

[0029] When the drive shaft 9 is twisted in this manner, and a shift operation is performed to select a driving range other than the parking range, the twist of the drive shaft 9 is released at the moment the lock on the intermediate shaft 5 by the parking lock mechanism 11 is released. When this twist of the drive shaft 9 is released, the torque pulsates according to the elastic modulus of the drive shaft 9. Specifically, after the amount of twist of the drive shaft 9 decreases toward "0", the drive shaft 9 twists in the opposite direction, and then the amount of twist of the drive shaft 9 decreases toward "0" again. In this way, the direction of twist of the drive shaft 9 reverses, and the amount of twist (peak value) gradually decreases. As a result, the case 17 vibrates, and this vibration is transmitted to the vehicle body 19 via the mount 18 while being dampened. As a result, the vehicle Ve may vibrate.

[0030] Therefore, when the drive shaft 9 is twisted, the motor 1 outputs an assist torque to counteract the torsional torque accumulated in the drive shaft 9, thereby suppressing vibrations when the parking lock mechanism 11 is released.

[0031] On the other hand, because there is no sensor to detect the torsional torque of the drive shaft 9, it may not be possible to perfectly match the assist torque output from the motor 1 with the torsional torque of the drive shaft 9. Also, if the motor 1 outputs an assist torque greater than the torsional torque of the drive shaft 9, the amount of twisting of the drive shaft 9 may actually increase. When the assist torque of the motor 1 is reduced, the time it takes for the torque of the motor 1 to decrease will be longer, or vibration may occur when the torque of the motor 1 is reduced and the torsional torque is released.

[0032] Therefore, the assist torque output from motor 1 is controlled to be less than or equal to the estimated torsional torque of drive shaft 9. In other words, when the parking lock mechanism 11 is released, the rotating member, including motor 1 connected to drive shaft 9, rotates (moves) due to the torsional torque, and the vehicle Ve vibrates as a result. The rotational speed (or rotational angle) of this rotating member fluctuates due to the pulsation of the torsional torque of drive shaft 9. Therefore, for example, if motor 1 is outputting assist torque to counteract the torsional torque accumulated in drive shaft 9, the assist torque is applied to the reversed torsional torque when the parking lock mechanism 11 is released and the direction of the torsional torque of drive shaft 9 is reversed. Therefore, if the assist torque is continuously output, it may contribute to an increase in the rotational speed (or rotational angle) of the rotating member. In other words, it may not be possible to quickly dampen the torsional torque.

[0033] The vehicle control device in this embodiment of the invention is configured to rapidly attenuate torsional torque by reducing the assist torque from the motor 1 at an appropriate timing. An electronic control device (hereinafter referred to as ECU) for controlling the motor 1 in this manner is provided in the vehicle Ve. This ECU 21 is mainly composed of a microcomputer and is configured to control the output torque of the motor 1 based on input signals and pre-stored calculation formulas. This ECU 21 corresponds to the "controller" in this embodiment of the invention.

[0034] In the example shown in Figure 1, the ECU 21 is connected to an acceleration sensor 22 that detects the longitudinal acceleration of the vehicle Ve, a resolver 23 that detects the rotational speed (rotation angle) of the motor 1, and a shift sensor 25 that detects the driving range selected by the shift device 24, and signals are input from these sensors 22, 23, and 25. In addition, the ECU 21 is connected to an EPB-ECU 26 that controls the EPB 15 and a B-ECU 27 that controls the brake device 14, and signals are input from these ECUs 26 and 27.

[0035] The above-described shift device 24 may be a so-called momentary type shift device in which, for example, when the driver operates the shift lever 28 to a shift position corresponding to the driving range desired by the driver, a shift sensor 25 corresponding to that shift position is turned on, a signal is input to the ECU 21, and when the operation of the shift lever 28 is released, the shift lever 28 returns to a predetermined standby position. The shift device 24 may also be provided with a parking button for selecting a parking range, and the shift sensor 25 may include a sensor that is turned on when the parking button is pressed.

[0036] Furthermore, the EPB-ECU26 is connected to, for example, the shift sensor 25, and based on the signal input from the shift sensor 25, it determines whether or not the EPB 15 is operating, and based on the result of that determination, it outputs a command signal to the ECU21 and the motor 16. In addition, the B-ECU27 receives signals such as the amount of brake pedal depression or pedal force or master cylinder pressure, or signals that detect hydraulic pressure or electromagnetic force to generate braking torque for the brake device 14, and based on these signals, it determines the braking torque to be applied to the brake device 14 or the braking torque that is currently applied to the brake device 14. Then it outputs a signal representing the magnitude of that braking torque to the ECU21.

[0037] Figure 2 shows a block diagram illustrating the functional configuration of the ECU 21. The ECU 21 shown in Figure 2 comprises a parking determination unit 29, a prediction unit 30, a torsional torque estimation unit 31, a motor control start unit 32, and a motor control end unit 33.

[0038] The parking determination unit 29 determines whether the vehicle is in a parking range where the rotation of the intermediate shaft 5 is prohibited by the parking lock mechanism 11, or in other words, whether it is in a locked state where the rotation of the intermediate shaft 5 is prohibited. Specifically, it determines whether the vehicle is in a parking range based on whether a predetermined time has elapsed since the parking range was selected by a shift operation, or based on a command signal to the actuator that operates the parking pole 13.

[0039] The prediction unit 30 predicts that the driving range will be switched from the parking range to another driving range. Specifically, as described above, if the shift device 24 is a momentary type shift device, it predicts that the driving range will be switched when the shift lever 28 is operated and the shift sensor 25 is turned on. The shift device 24 may also be a conventional gate type shift device in which a gate is assigned a position corresponding to the selected driving range, and the shift lever is operated within that gate, and the shift lever maintains its position when the driver releases their hand from the shift lever. In the case of such a gate type shift device, it may also predict that the driving range will be switched from the parking range to another driving range when the shift button for moving the shift lever from the parking range is turned on.

[0040] The torsional torque estimation unit 31 estimates the torsional torque of the drive shaft 9. Specifically, as described above, when the vehicle Ve is tilted in the pitching direction, the drive shaft 9 twists as the wheels 10 rotate, and the torque corresponding to the amount of twist of the drive shaft 9 and the elastic modulus becomes the torsional torque of the drive shaft 9. Therefore, for example, the torsional torque of the drive shaft 9 is estimated based on the tilt angle of the vehicle Ve detected by the acceleration sensor 22.

[0041] The motor control start unit 32 controls motor 1 to begin outputting an assist torque from motor 1 that counteracts the torsional torque estimated by the torsional torque estimation unit 31 when the prediction unit 30 predicts that the vehicle will switch from the parking range to another driving range. In other words, the motor control start unit 32 controls motor 1 to begin outputting torque from motor 1 based on the signal from the shift sensor 25.

[0042] The motor control termination unit 33 terminates the output of torque from motor 1 when motor 1, which is outputting assist torque, begins to rotate, in order to prevent motor 1 from continuing to output torque. Specifically, based on the value detected by the resolver 23, the motor control termination unit 33 terminates the output of assist torque from motor 1 when the rotational speed of motor 1 exceeds a predetermined rotational speed, or when motor 1 rotates by an angle greater than or equal to a predetermined angle. This is because when motor 1 rotates (or moves), it is assumed that the parking lock mechanism 11 has been released.

[0043] Furthermore, if the assist torque output from motor 1 matches the torsional torque of drive shaft 9, motor 1 may not rotate even if the parking lock mechanism 11 is released. Therefore, the motor control termination unit 33 terminates the output of assist torque from motor 1 when a driving range other than the parking range is determined, or in other words, when the parking lock mechanism 11 is released.

[0044] Furthermore, even if a shift operation is performed to switch from the parking range to another driving range, the request to switch driving ranges will be rejected if the brakes are not applied or if the brakes are released before the driving range is determined. In such cases, the driving range will not be switched, and the parking lock mechanism 11 will remain locked. In this case, if the motor 1 continues to output assist torque, power consumption will increase, or the electronic components for controlling the motor 1 may overheat, potentially reducing their durability. Therefore, the motor control termination unit 33 terminates the output of assist torque from the motor 1 after a predetermined time has elapsed since the motor 1 began outputting assist torque.

[0045] Figure 3 shows a flowchart illustrating an example of control for determining whether or not to output assist torque from motor 1. In the control example shown in Figure 3, first, it is determined whether or not the condition for ending the output of assist torque from motor 1 has been met (step S1). Specifically, it is determined whether or not the assist torque has been continuously output for a predetermined time or longer, and more specifically, whether or not the assist torque has been output from motor 1 for a predetermined time or longer, taking into account the increase in power consumption due to the output of assist torque from motor 1 and the durability of the electronic components used to energize motor 1. This determination can be made based on whether or not the assist execution counter, which will be described later, is equal to or greater than a predetermined value. This predetermined value can be set to a value longer than the time required from the time it is requested to release the parking lock mechanism 11 until the parking lock mechanism 11 is released, which can be determined by experimentation or other means.

[0046] Furthermore, it is determined whether the lock on the drive shaft 9 by the parking lock mechanism 11 has been released, or more specifically, whether a driving range other than the parking range is set. In addition, it is determined whether the twist of the drive shaft 9 has been resolved, or more specifically, whether the absolute value of the rotational speed (rotation angle) of the motor 1 is equal to or greater than a predetermined rotational speed (predetermined rotation angle). Moreover, it is determined whether any abnormality has occurred that prevents proper control of the torque acting on the drive shaft 9, such as a communication failure between the ECU 21 and the EPB-ECU 26 or B-ECU 27 while the motor 1 is outputting assist torque, that is, whether the abnormality determination flag is turned on.

[0047] If at least one of the following conditions is met in step S1, such that the assist execution counter is above a predetermined value, a driving range other than the parking range is set, the absolute value of the rotational speed of motor 1 is above a predetermined rotational speed, or the abnormality judgment flag is on, then the flag for executing control to output assist torque from motor 1 (hereinafter referred to as the motor control execution flag) is set to off (step S2).

[0048] Conversely, if the assist execution counter is below a predetermined value, the parking range is set, the absolute value of the motor 1's rotational speed is below a predetermined rotational speed, and the abnormality judgment flag is off, and a negative determination is made in step S1, then a shift operation is performed to select a driving range other than the parking range, the twisting judgment flag is on, and it is determined whether the tilt angle in the pitching direction of the vehicle Ve is greater than or equal to a predetermined tilt angle (step S3). The twisting judgment flag in step S3 is a flag that is set to turn on when the conditions for the drive shaft 9 to twist are met. For example, it is set to turn on when the rotation on the input side of the drive shaft 9 is prohibited, while the wheels 10 are able to rotate, such as when the parking range is set and sufficient braking torque is not acting on the wheels 10. In other words, the twisting judgment flag is a flag that determines whether the drive shaft 9 is twisted. Furthermore, the predetermined inclination angle in step S3 can be set to the inclination angle at which the wheel 10 rotates (rotates) if no braking torque is applied to the wheel 10.

[0049] If a shift operation is performed to select a driving range other than the parking range, the torsion detection flag is on, and the pitching angle of the vehicle Ve is greater than or equal to a predetermined angle, and a positive determination is made in step S3, the motor control execution flag is set to on (step S4). That is, motor 1 outputs an assist torque. The assist torque of motor 1 is a torque that counteracts the torsional torque corresponding to the tilt angle of the vehicle Ve, and is set to be less than or equal to the torsional torque estimated from the tilt angle.

[0050] Conversely, if a shift operation to select a driving range other than the parking range is not performed, or the torsion detection flag is off, or the tilt angle in the pitching direction of the vehicle Ve is less than a predetermined tilt angle, and a negative determination is made in step S3, the motor control execution flag is maintained (step S5).

[0051] Following steps S2, S4, and S5, it is determined whether the motor control execution flag is on (step S6). If the motor control execution flag is on and the determination in step S6 is positive, the assist execution counter is incremented (step S7) and this routine is terminated. Conversely, if the motor control execution flag is off and the determination in step S6 is negative, the assist execution counter is set to "0" (step S8) and this routine is terminated.

[0052] Figure 4 shows a time chart illustrating the changes in the driving range, shift position, vehicle Ve tilt angle, motor control execution flag, assist execution counter, and motor rotation speed (absolute value) when the motor control execution flag is switched off due to the motor 1 rotation speed exceeding a predetermined rotation speed. Figure 4 also shows an example using a momentary type shift device 24.

[0053] In the example shown in Figure 4, at time t0, the parking range (P) is set, and the tilt angle of the vehicle Ve is abnormally high. Consequently, the twist detection flag is turned on. On the other hand, because the shift lever 28 is in the standby position (Home), switching the driving range is not expected. Therefore, the motor control execution flag is turned off.

[0054] At time t1, the shift operation has begun. Specifically, the shift operation is performed to switch the driving range from the parking range to the drive range (D). In this example, the shift lever 28 is moved to the drive position at time t2 via the neutral position (N). At time t3, the driver releases their hand from the shift lever 28, and the shift position returns to the standby position.

[0055] At time t1, the shift operation is initiated, which predicts a switch in the driving range from the parking range to another driving range. This is positively judged in step S3 of the control example above. As a result, the motor control execution flag is switched on, and the assist execution counter begins to count up. That is, the motor 1 begins to output an assist torque determined based on the tilt angle of the vehicle Ve. As mentioned above, the assist torque is smaller than the torsional torque. Therefore, the rotational speed of the motor 1 does not fluctuate because the parking gear 12 is in contact with the parking pawl 13 and rotation is prohibited.

[0056] In the example shown in Figure 4, the parking lock mechanism 11 is switched to the released state before t4. As a result, the load bearing the torsional torque caused by the meshing of the parking gear 12 and the parking pawl 13 decreases, and the excess torque obtained by subtracting the assist torque from the torsional torque is transmitted to the motor 1, causing the motor 1 to start rotating. Consequently, at t4, the motor speed exceeds the predetermined speed, and the motor control execution flag is switched to off. In other words, the motor 1 stops outputting assist torque. Note that in the example shown in Figure 4, the driving range is switched to the drive range after t4.

[0057] As described above, even before the parking lock mechanism 11 is released, the motor 1 outputs an assist torque to counteract the torsional torque, thereby reducing the contact load between the parking gear 12 and the parking pawl 13. In other words, it is possible to suppress a sudden change in the torque acting on the drive shaft 9 when the parking lock mechanism 11 is released. As a result, the torque transmitted from the drive shaft 9 to the motor 1 can be reduced when the parking lock mechanism 11 is released. That is, fluctuations in the rotational speed of the torque transmission section between the motor 1 and the drive shaft 9 can be suppressed, and vibration of the vehicle Ve can be suppressed.

[0058] Furthermore, when the rotational speed of motor 1 exceeds a predetermined rotational speed, the motor 1 stops outputting assist torque. In other words, the motor 1 stops outputting assist torque without needing to determine that the parking lock mechanism 11 has switched to the released state. Therefore, the assist torque can be reduced before the direction of the torsional torque reverses. As a result, the increase in vibration caused by the assist torque being added to the reversed torsional torque can be suppressed, or in other words, the decrease in the vibration damping effect of the torque transmission part including motor 1 after the parking lock mechanism 11 is released can be suppressed. In other words, the vibration of the vehicle Ve can be reduced rapidly.

[0059] As described above, when the parking lock mechanism 11 is released while the motor 1 is outputting assist torque, the rotational speed of the motor 1 usually changes, so it is possible to determine that the parking lock mechanism 11 has been released based on the rotational speed of the motor 1. On the other hand, there are cases where the rotational speed of the motor 1 does not change even when the parking lock mechanism 11 is released, for example, if the assist torque of the motor 1 matches the torsional torque of the drive shaft 9. In such cases, if the motor 1 continues to output torque, when the torsional torque of the drive shaft 9 reverses, the assist torque of the motor 1 will be added, which may amplify vibrations. In addition, it may increase power consumption due to the continuous supply of power to the motor 1 and reduce the durability of the electronic components that supply power to the motor 1.

[0060] Therefore, in the control example shown in Figure 3, the motor control execution flag is switched to off when a driving range other than the parking range is set. Figure 5 shows a time chart to explain the changes in the driving range, vehicle Ve tilt angle, shift position, motor speed, and motor control execution flag when the motor control execution flag is switched to off due to the setting of a driving range other than the parking range. Figure 5 also shows a time chart to explain the changes in the abnormality detection flag, driving range, vehicle Ve tilt angle, shift position, motor speed, and motor control execution flag when the motor control execution flag is switched to off based on the abnormality detection flag.

[0061] As shown in Figure 5, at time t10, the parking range (P) is set, and the tilt angle of the vehicle Ve is greater than or equal to a predetermined angle. Consequently, the twist detection flag is turned on. On the other hand, since the shift lever 28 is in the standby position (Home), switching the driving range is not expected. Therefore, the motor control execution flag is turned off.

[0062] At time t11, the shift operation has begun. That is, the vehicle has been switched from the parking range selection position (P) to another position (for example, the drive position (D)). As a result, the motor control execution flag is switched on because it is predicted that the driving range will be switched from the parking range to another driving range. That is, the motor 1 begins to output an assist torque determined based on the tilt angle of the vehicle Ve. As mentioned above, the assist torque is less than or equal to the torsional torque. Therefore, the rotational speed of the motor 1 does not fluctuate because the parking gear 12 is in contact with the parking pawl 13 and rotation is prohibited.

[0063] On the other hand, at time t12, the abnormality detection flag was switched on due to some factor, causing the motor control execution flag to be switched off. In other words, the output of assist torque from motor 1 is terminated.

[0064] As described above, if an abnormality occurs that prevents proper control of the torque acting on the drive shaft 9, switching the motor control execution flag to off can suppress situations where the assist torque exacerbates twisting of the drive shaft 9 or vibrations and shocks at the time the parking lock mechanism 11 is released.

[0065] Furthermore, in the example shown in Figure 5, the abnormality detection flag is switched off at t13 when communication between ECU21 and EPB-ECU26 or B-ECU27 is restored by restarting ECU21, EPB-ECU26, or B-ECU27.

[0066] Furthermore, at t14, the shift operation is initiated again. That is, the position for selecting the parking range (P) is switched to another position. As a result, the motor control execution flag is switched on because it is predicted that the driving range will be switched from the parking range to another driving range. That is, the motor 1 begins to output an assist torque determined based on the tilt angle of the vehicle Ve. As mentioned above, the assist torque is less than or equal to the torsional torque. Therefore, the rotational speed of the motor 1 does not fluctuate because the parking gear 12 is in contact with the parking pawl 13 and rotation is prohibited.

[0067] Then, at t15, the parking lock mechanism 11 switches to the released state without the motor rotation speed changing, and the vehicle switches to a driving range other than the parking range, causing the motor control execution flag to be switched off.

[0068] As described above, when the vehicle switches to a driving range other than the parking range, the parking lock mechanism 11 is released, and it is believed that vibrations and shocks will not occur due to the release of the torsional torque of the drive shaft 9. In such cases, the output of assist torque from the motor 1 can be prevented from causing unintended movement or vibration of the vehicle Ve. In other words, the vehicle's rotational speed does not change because the torsional torque and assist torque match, and the vehicle's driving range is determined as a backup by stopping the output of the assist torque. As a result, unintended behavior of the vehicle Ve can be prevented.

[0069] Furthermore, for example, if a shift operation to switch from the parking range to another driving range is permitted only when the brake pedal is depressed, more specifically, if brake operation is required until the other driving range is determined, then if the brake operation is released between the time the shift operation is performed and the time the other driving range is determined, the driving range will not be switched. In other words, the parking lock mechanism 11 will not switch to the released state. Therefore, even if the motor 1 that has been shifted starts outputting assist torque, if the motor 1 continues to output assist torque when the above-mentioned driving range switch does not occur, power consumption may increase, or the electronic components that supply power to the motor 1 may overheat, or the durability of those electronic components may decrease.

[0070] Therefore, in the control example shown in Figure 3, the motor control execution flag is switched off when the time elapsed since the motor control execution flag was turned on exceeds a predetermined value, or more specifically, when the assist execution counter exceeds a predetermined value. Figure 6 shows a time chart illustrating the changes in the driving range, the inclination angle of the vehicle Ve, the motor control execution flag, the motor speed, and the assist execution counter when the motor control execution flag is switched off due to the assist execution counter exceeding a predetermined value.

[0071] At time t20 shown in Figure 6, the parking range (P) is set, and the tilt angle of the vehicle Ve is greater than or equal to a predetermined angle. Consequently, the twist detection flag is turned on. On the other hand, since the shift lever 28 is in the standby position (Home), switching the driving range is not expected. Therefore, the motor control execution flag is turned off.

[0072] At time t21, the shift operation has begun. That is, the position for selecting the parking range (P) has been switched to another position. As a result, the motor control execution flag has been switched on because it is predicted that the driving range will be switched from the parking range to another driving range. That is, the motor 1 begins to output an assist torque determined based on the tilt angle of the vehicle Ve. As mentioned above, the assist torque is less than or equal to the torsional torque. Therefore, the rotational speed of the motor 1 does not fluctuate because the parking gear 12 is in contact with the parking pawl 13 and rotation is prohibited.

[0073] On the other hand, in the example shown in Figure 6, the parking lock mechanism 11 is not switched to the released state after the shift operation. In other words, the driving range remains in the parking range. Therefore, the assist execution counter continues to increase from time t21, and at time t22, the assist execution counter reaches a predetermined value. As a result, the motor control execution flag is switched to off. That is, the output of assist torque from motor 1 is terminated.

[0074] As described above, if the assist execution counter exceeds a predetermined value, the parking lock mechanism 11 is not released based on the shift operation that determined that motor 1 should output assist torque. In such cases, by ending the output of assist torque from motor 1, the increase in power consumption caused by continuously outputting assist torque from motor 1 can be suppressed. In addition, it is possible to suppress the overheating of electronic components connected to motor 1, thereby suppressing a decrease in the durability of those electronic components. In other words, it can function as a backup to stop the output of assist torque when the parking lock mechanism 11 does not transition to the released state.

[0075] Furthermore, the vehicle in this embodiment of the invention is not limited to a vehicle in which a motor is connected to each wheel, but may also be a vehicle configured to transmit torque from a single motor to a pair of front or rear wheels, or to all wheels. In addition, it may be a hybrid vehicle equipped with an engine as a driving force source in addition to the motor. Moreover, the configuration connecting the motor 1 and the drive shaft 9, and the rotating member whose rotation is prohibited by the parking lock mechanism 11, are not limited to those shown in Figure 1. Furthermore, the vehicle in this embodiment of the invention may not be equipped with an EPB 15. [Explanation of symbols]

[0076] 1,16 motor 2.8 Output shaft 3.6 drive gear 4.7 Driven gear 5 Intermediate axis 9 Drive shaft 10 wheels 11 Parking lock mechanism 12 Parking lock gear 13 Parking poles 14 Brake system 15. Electric Parking Brake (EPB) 17 cases 18 Mount 19 car bodies 20 Suspension 21 Electronic Control Unit (ECU) 22 Accelerometer 23 resolvers 24 Shift device 25 Shift Sensor 26 EPB-ECU 27 B-ECU 28 Shift lever 29 Parking determination unit 30 Prediction Section 31 Torsional Torque Estimation Unit 32 Motor control start unit 33 Motor control termination section Vehicle

Claims

1. A vehicle control device comprising: a drive shaft with one end connected to a wheel; a motor capable of transmitting torque to the drive shaft; and a parking lock mechanism capable of selectively switching between a locked state in which the rotation of a predetermined rotating member between the motor and the drive shaft is prohibited and an unlocked state in which the predetermined rotating member is rotatable, The motor is equipped with a controller that controls the motor, The aforementioned controller, A parking determination unit that determines whether the parking lock mechanism is in the locked state, A prediction unit that predicts when the parking lock mechanism will switch from the locked state to the unlocked state, A torsional torque estimation unit for estimating the torsional torque of the drive shaft, A motor control start unit, which, when it is predicted that the parking lock mechanism will switch from the locked state to the unlocked state, counteracts the estimated torsional torque of the drive shaft and starts outputting a torque from the motor that is less than or equal to the torsional torque, The system includes a motor control termination unit that terminates the output of torque from the motor when the motor, which is outputting torque, begins to rotate. A vehicle control device characterized by the following features.

2. A vehicle control device according to claim 1, The motor control termination unit terminates the output of torque from the motor when a predetermined time has elapsed since the motor began outputting torque. A vehicle control device characterized by the following features.

3. A vehicle control device according to claim 1, The motor control termination unit terminates outputting torque from the motor when the parking lock mechanism switches from the locked state to the unlocked state. A vehicle control device characterized by the following features.

4. A vehicle control device according to any one of claims 1 to 3, The parking lock mechanism further comprises a shift device operated by the driver to select a desired driving range from a plurality of driving ranges, including the parking range in which the parking lock mechanism is in the locked state. The prediction unit predicts that when a shift operation is performed to select another driving range from the parking range in which the parking lock mechanism will be in the released state, the parking lock mechanism will switch from the locked state to the released state. A vehicle control device characterized by the following features.

5. A vehicle control device according to any one of claims 1 to 3, The torsional torque estimation unit estimates the torsional torque of the drive shaft based on the tilt angle in the pitching direction of the vehicle. A vehicle control device characterized by the following features.

Images