Control device for a vehicle

Abstract

This invention provides a vehicle control device capable of suppressing vibration or impact when a parking lock mechanism is released while the drive shaft is in a torsional state. The vehicle includes: a drive shaft, one end of which is 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 that prevents rotation of a predetermined rotating component between the motor and the drive shaft, and a released state that allows rotation of the predetermined rotating component. The vehicle control device controls the motor based on the auxiliary torque at the moment the parking lock mechanism is switched to the released state, a reduction rate set such that the auxiliary torque becomes zero after a predetermined time has elapsed since the moment the parking lock mechanism is switched to the released state, and the elapsed time since the moment the parking lock mechanism is switched to the released state (steps S8 and S9).

Description

Technical Field

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

[0002] Patent Document 1 describes a vehicle control device, which includes a parking lock mechanism that prevents the rotation of a drive shaft connected to the wheels by engaging a parking gear linked to the wheels with a parking pawl, and allows the drive shaft to rotate by disengaging the engagement.

[0003] In the parking lock mechanism described in Patent Document 1, a shift lever operated by the driver is mechanically connected to a parking pawl. Therefore, when the load acting on the meshing surface of the parking gear and parking pawl is large, the operating force required to disengage the gear lever increases. Therefore, the control device described in Patent Document 1 is configured to output torque from the motor in a direction that reduces the meshing load between the parking lock gear and parking pawl. Specifically, it is configured to gradually increase the output torque of the motor and maintain the torque at the moment the motor's rotation angle changes, thereby reducing the meshing load between the parking lock gear and parking pawl. Furthermore, this control device is configured to set the motor's output torque to "0" when it is determined that the parking lock mechanism is in a disengaged state.

[0004] Patent Document 1: Japanese Patent No. 3454009 Summary of the Invention

[0005] The control device described in Patent Document 1 reduces the operating force 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 eliminated. That is, it increases the torque on the drive shaft. Furthermore, when the control device determines that the parking lock mechanism is in the released state, it sets the motor's output torque to zero. Therefore, at the moment the motor's output torque is set to zero, the torsional torque caused by the drive shaft's rotation is transmitted to the motor or the torque transmission component between the motor and the drive shaft. This torsional torque pulsates according to the drive shaft's elastic coefficient. Therefore, during the reduction of drive shaft rotation, vibrations or impacts caused by these torsional torque pulsations may occur.

[0006] This invention was made in view of the above-mentioned technical problems. The purpose of this invention is to provide a vehicle control device that can suppress vibration or impact when the parking lock mechanism is released under the condition of drive shaft torsion.

[0007] To achieve the above objectives, the present invention provides a vehicle control device, the vehicle comprising: a drive shaft, one end of which is 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, which prevents rotation of a predetermined rotating component between the motor and the drive shaft, and an unlocked state, in which the predetermined rotating component can rotate; wherein, when the parking lock mechanism is in the locked state, an auxiliary torque is output from the motor to counteract the torsional torque accompanying the torsion of the drive shaft; the vehicle control device comprising a controller for controlling the motor, the controller comprising: a switching determination unit that determines that the parking lock mechanism has switched from the locked state to the unlocked state; a rate setting unit that sets a reduction rate of the auxiliary torque such that the auxiliary torque becomes zero after a predetermined time has elapsed since the moment the parking lock mechanism switched to the unlocked state; and a motor control unit that controls the motor based on the auxiliary torque, the reduction rate, and the elapsed time since the moment the parking lock mechanism switched to the unlocked state.

[0008] Furthermore, in this invention, the specified time can be a time set according to the inherent vibration number of the drive shaft.

[0009] Furthermore, in this invention, the specified time can be half a cycle time based on the natural vibration number of the drive shaft.

[0010] Furthermore, in this invention, the rate setting unit may include the rate obtained by dividing the auxiliary torque at the moment when the parking lock mechanism is switched to the released state by the predetermined time.

[0011] Furthermore, in this invention, the controller may further include: an anomaly determination unit that determines an anomaly in which the torque acting on the drive shaft cannot be properly controlled; and a rate setting unit that, when determining that the torque acting on the drive shaft cannot be properly controlled, sets the rate of decrease of the auxiliary torque in such a short time as to make the auxiliary torque zero.

[0012] Invention Effects

[0013] In this invention, the vehicle control device outputs an auxiliary torque from the motor that counteracts the torsional torque accompanying the rotation of the drive shaft when the parking lock mechanism is in a locked state, preventing the rotation of a predetermined rotating component connected to the drive shaft. Furthermore, the rate of decrease of the auxiliary torque is set such that the auxiliary torque becomes zero after a predetermined time elapses from the moment the parking lock mechanism switches from the locked state to the released state where the predetermined rotating component can rotate. Therefore, the output of the auxiliary torque can be stopped before the direction of the torsional torque of the drive shaft reverses when the parking lock mechanism is released. In other words, the auxiliary torque can decrease as the torsional torque of the drive shaft decreases. Therefore, during the decrease of the torsional torque of the drive shaft, the auxiliary torque counteracting this torsional torque can act on the drive shaft to suppress vibration. Furthermore, after the direction of the torsional torque of the drive shaft reverses, the auxiliary torque applied to this torsional torque can suppress the increase in the amount of torsion of the drive shaft. As a result, the pulsating torsional torque of the drive shaft can be rapidly attenuated. That is, the effect of reducing vehicle vibration can be improved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating an example of a vehicle in an embodiment of the present invention.

[0015] Figure 2 It is a block diagram used to illustrate the functional structure of the controller.

[0016] Figure 3 This is a flowchart illustrating an example of setting the control of the torque output from the motor.

[0017] Figure 4 It is a timing diagram used to illustrate the rate of decrease corresponding to the auxiliary torque.

[0018] Figure 5 It is used to describe the execution Figure 3 The timing diagram shows an example of the changes in the vehicle's tilt angle, shift position, driving gear, motor control execution flag, speed processing flag, and auxiliary torque (execution value) under the control example shown. Detailed Implementation

[0019] The present invention will be described with reference to the embodiments shown in the figures. Furthermore, the embodiments described below are merely examples of how the present invention is being implemented and are not intended to limit the scope of the invention.

[0020] exist Figure 1 An example of a vehicle in an embodiment of the present invention is illustrated schematically. Figure 1The vehicle Ve shown is an electric vehicle equipped with a motor (MG) 1 as a drive power source. The motor 1 can be configured to be the same as conventional motors used as drive power sources in electric or hybrid vehicles. That is, in addition to functioning as a motor that generates drive torque by supplying electricity through an energy storage device (not shown), it also functions as a generator that converts at least a portion of the power from the output shaft 2 into electrical electricity by being driven by the output shaft 2. Specifically, it is composed of a permanent magnet synchronous motor or an induction motor, etc.

[0021] A first drive gear 3 is mounted on the output shaft 2 of the motor 1. A first driven gear 4, which meshes with the first drive gear 3 and has a larger diameter than the first drive gear 3, is mounted on an intermediate shaft 5 that is parallel to the output shaft 2 of the motor 1. That is, the first drive gear 3 and the first driven gear 4 constitute a reduction gear pair.

[0022] A second drive gear 6 is also mounted on the intermediate shaft 5. A second driven gear 7, which meshes with the second drive gear 6 and has a larger diameter than the second drive gear 6, is mounted on the output shaft 8, which is arranged parallel to the output shaft 2 of the motor 1 and the intermediate shaft 5. That is, the second drive gear 6 and the second driven gear 7 constitute a reduction gear pair. On the output shaft 8, one end of the drive shaft 9 is connected in a manner that allows it to rotate integrally, and the wheel 10 is connected to the other end of the drive shaft 9.

[0023] Furthermore, a parking lock mechanism 11 is provided that can selectively switch between a locked state that prevents the rotation of the intermediate shaft 5 and an unlocked state that allows the intermediate shaft 5 to rotate. This parking lock mechanism 11 can be configured to be the same as those provided in conventional vehicles. Specifically, the parking lock mechanism 11 consists of a parking lock gear 12 mounted on the intermediate shaft 5, a parking pawl 13 that can selectively engage with the parking lock gear 12, and an actuator (not shown) that actuates the parking pawl 13. When the parking gear is selected via the shift device 24 (described later), the parking pawl 13 is rotated by the actuator (not shown) and engages with the parking lock gear 12. By engaging the parking pawl 13 with the parking lock gear 12, rotation of the parking lock gear 12 is prevented. Therefore, rotation of the drive shaft 9, which is torque-transmittingly connected to the parking lock gear 12 via the intermediate shaft 5, is prevented.

[0024] exist Figure 1The vehicle Ve shown is equipped with a braking device 14 that applies braking torque to the wheels 10 corresponding to the amount of operation of a brake pedal (not shown) operated by the driver. This braking device 14 can be configured similarly to those found in conventional vehicles. That is, it can be a disc brake that applies braking torque to the wheels 10 by clamping a brake disc that rotates integrally with the wheels 10 with brake pads, or a drum brake that applies braking torque to the wheels 10 by pressing the brake shoes from the inside of a drum that rotates integrally with the wheels 10. Furthermore, the clamping force of these brake pads or the pressing force of the brake shoes can be controlled by an actuator (not shown) that generates hydraulic pressure or electromagnetic force based on the amount of brake pedal operation.

[0025] In addition, Figure 1 The vehicle Ve shown is equipped with an electric parking brake (hereinafter referred to as EPB) 15. This EPB 15 is configured similarly to those found in conventional vehicles. When the parking gear is selected, the motor 16 actuates, driving a caliper or brake shoe (not shown) to apply braking torque to the wheel 10. When a driving gear other than parking is selected, this braking torque is reduced. Furthermore, from the viewpoint of performance considerations, the motor 16 can be mounted on the vehicle body, and a cable connecting the motor 16 to the caliper or brake shoe can be provided. By rotating the motor 16, the cable is wound to drive the caliper or brake shoe.

[0026] exist Figure 1 In the example shown, the motor 1, the gear train that transmits torque from the motor 1 to the output shaft 8, and the output shaft 8 are housed in a housing 17, which is connected to the vehicle body 19 via a mounting member 18. Furthermore, the wheels 10 are held to the vehicle body 19 via a suspension device 20.

[0027] exist Figure 1 In the vehicle Ve shown, when the brake pedal is engaged and the driver performs a shift operation to select the parking gear, it is permissible to switch from driving to parking gear. When the vehicle is switched to parking gear, the parking lock mechanism 11 prevents the rotation of the intermediate shaft 5, and the EPB 15 applies braking torque to the wheels 10.

[0028] As described above, the time from shifting gears to stopping the rotation of the intermediate shaft 5 via the parking lock mechanism 11 is sometimes faster than the time it takes to apply braking torque to the wheels 10 via the EPB 15. Therefore, for example, in situations where the vehicle Ve is parked on a slope or with its wheels resting on an object, or where the vehicle Ve is tilted in the pitch direction, if the driver reduces the amount of braking on the brake pedal before applying braking torque to the wheels 10 via the EPB 15, rotation on the input side of the drive shaft 9 is stopped, while the wheels 10 rotate. Furthermore, if the EPB 15 cannot be activated for some reason, after the driver reduces the amount of braking on the brake pedal, rotation on the input side of the drive shaft 9 is stopped, while the wheels 10 rotate. As a result, the drive shaft 9 twists. In other words, a torque corresponding to its elastic coefficient and torsional amount (hereinafter referred to as torsional torque) accumulates in the drive shaft 9.

[0029] The amount of torsion (i.e., torsional torque) of the drive shaft 9 corresponds to the tilt angle of the vehicle Ve. Specifically, a load in the longitudinal direction acting on the vehicle Ve, corresponding to the tilt angle of the vehicle Ve, acts on the contact surface between the wheel 10 and the road surface, and a torque corresponding 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 is locked and does not rotate by the parking lock mechanism 11. Therefore, the drive shaft 9 gradually twists, generating a torsional torque corresponding to its amount of torsion and the elastic coefficient of the drive shaft 9. Then, at the moment when the torque from the wheel 10 acting on the drive shaft 9 is balanced with the torsional torque corresponding to the amount of torsion of the drive shaft 9, the amount of torsion of the drive shaft 9 is maintained. In addition, the direction of torsion of the drive shaft 9 corresponds to the tilt direction of the vehicle Ve in the pitch direction.

[0030] Thus, if a gear shift is performed while the drive shaft 9 is twisted and a driving gear other than parking is selected, the twisting of the drive shaft 9 is eliminated when the intermediate shaft 5 is released from the parking lock mechanism 11. During the elimination of the twisting of the drive shaft 9, torque pulsation occurs according to the elastic coefficient of the drive shaft 9. Specifically, after the amount of twisting of the drive shaft 9 decreases towards "0", the drive shaft 9 twists in the opposite direction, and then the amount of twisting of the drive shaft 9 decreases towards "0" again. Thus, while the twisting direction of the drive shaft 9 reverses, the amount of twisting (peak value) gradually decreases. As a result, the housing 17 vibrates, and this vibration is attenuated by the mounting member 18 and transmitted to the vehicle body 19. Consequently, the vehicle Ve may vibrate.

[0031] Therefore, when the drive shaft 9 is twisted, by outputting auxiliary torque from the motor 1 to counteract the torsional torque stored in the drive shaft 9, vibration can be suppressed when the parking lock mechanism 11 is released.

[0032] On the other hand, since no sensor is provided to detect the torsional torque of the drive shaft 9, it is sometimes impossible to make the auxiliary torque output from the motor 1 completely match the torsional torque of the drive shaft 9. Furthermore, if the auxiliary torque output from the motor 1 is greater than the torsional torque of the drive shaft 9, the torsion of the drive shaft 9 will actually increase. When the auxiliary torque of the motor 1 is reduced, the time for the torque of the motor 1 to decrease becomes longer, or vibration may occur if the torsional torque is released by reducing the torque of the motor 1.

[0033] Therefore, the auxiliary torque output from motor 1 is controlled to be below the estimated torsional torque of drive shaft 9. That is, when the parking lock mechanism 11 is released, the rotating component of motor 1 connected to drive shaft 9 rotates due to the torsional torque, and the vehicle vibrates. The rotational speed (or rotation angle) of this rotating component varies due to the pulsation of the torsional torque of drive shaft 9. Therefore, for example, if an auxiliary torque that counteracts the torsional torque accumulated on drive shaft 9 is continuously output from motor 1, then at the moment when the parking lock mechanism 11 is released and the torsional torque of drive shaft 9 reverses direction, the auxiliary torque is added to the reversing torsional torque. Therefore, it is possible to promote an increase in the rotational speed (or rotation angle) of the rotating component. That is, it is possible that the torsional torque may not be able to decay quickly.

[0034] In an embodiment of the present invention, the vehicle control device is configured to reduce the auxiliary torque at a predetermined rate, based on the moment when the torsional torque of the drive shaft 9 reverses direction, so that the auxiliary torque output from the motor 1 becomes "0". An electronic control device (hereinafter referred to as ECU) for controlling the motor 1 in this way is provided in the vehicle Ve. This ECU 21 is primarily composed of a microcomputer and is configured to control the output torque of the motor 1 based on input signals and pre-stored formulas. This ECU 21 corresponds to the "controller" in an embodiment of the present invention.

[0035] exist Figure 1 In the example shown, the ECU 21 is connected to an acceleration sensor 22 for detecting the front-rear acceleration of the vehicle Ve, a rotary transformer 23 for detecting the rotational speed (rotation angle) of the motor 1, and a shift sensor 25 for detecting the driving gear selected by the shift device 24. Signals are input from these sensors 22, 23, and 25. Furthermore, the ECU 21 is connected to an EPB-ECU 26 for controlling the EPB 15 and a B-ECU 27 for controlling the braking device 14. Signals are input from these ECUs 26 and 27.

[0036] The aforementioned shifting device 24 can be, for example, a so-called instantaneous type shifting device: the driver operates the shift lever 28 to a shift position corresponding to the driver's desired driving gear, the shift sensor 25 corresponding to this shift position is activated, a signal is input to the ECU 21, and by releasing the operation of the shift lever 28, the shift lever 28 returns to a predetermined standby position. Additionally, the shifting device 24 may include a parking button for selecting the parking gear, and the shift sensor 25 may include a sensor activated by pressing the parking button.

[0037] Furthermore, the aforementioned EPB-ECU26 is connected to, for example, the shift sensor 25. Based on the signal input from the shift sensor 25, it determines whether the EPB15 is activated, and based on the determination result, outputs a command signal to the ECU21 or the motor 16. Moreover, the B-ECU27 inputs signals such as the amount of brake pedal depressed, the pedal force, or the master cylinder pressure, or signals such as hydraulic pressure or electromagnetic force used to generate the braking torque of the braking device 14. Based on these signals, it calculates the braking torque acting on the braking device 14. Then, it outputs a signal indicating the magnitude of this braking torque to the ECU21.

[0038] exist Figure 2 The diagram shown illustrates the functional structure of ECU21. Figure 2 The ECU21 shown includes a switching determination unit 29, a target torque setting unit 30, a speed setting unit 31, a motor control unit 32, and an abnormality determination unit 33.

[0039] The switching determination unit 29 determines that the parking lock mechanism 11 is switching from a locked state, in which the intermediate shaft 5 is prohibited from rotating, to a released state, in which the intermediate shaft 5 can rotate. Specifically, for example, the rotational speed (or rotation angle) of the motor 1 when the parking lock mechanism 11 is in the locked state is stored. If the rotational speed (or rotation angle) of the motor 1 changes, the parking lock mechanism 11 is determined to switch from the locked state to the released state.

[0040] The target torque setting unit 30 counteracts the torsional torque accompanying the torsion of the drive shaft 9 and sets a target value for the auxiliary torque below this torsional torque (hereinafter referred to as the target auxiliary torque). Specifically, the tilt angle of the vehicle Ve is estimated based on the acceleration detected by the acceleration sensor 22, and the torsional torque of the drive shaft 9 is estimated based on this tilt angle, the elastic coefficient of the drive shaft 9, and the vehicle weight, etc. Then, the torque below the estimated torsional torque is set as the target auxiliary torque. In addition, since the amount of torsion (torsional torque) of the drive shaft 9 changes depending on whether the braking device 14 or EPB15 is activated or the timing of its activation, the torsional torque can be estimated based on the presence or absence of the braking device 14 or EPB15 or the timing of its activation.

[0041] The rate setting unit 31 sets the rate of reduction of the auxiliary torque so that the auxiliary torque of the motor 1 becomes zero after a predetermined time elapsed since the parking lock mechanism 11 switches from the locked state to the released state. That is, the rate is set by dividing the auxiliary torque of the motor 1 at the moment the parking lock mechanism 11 switches from the locked state to the released state by the predetermined time. Specifically, the rate of reduction is set so that the auxiliary torque of the motor 1 becomes zero at the moment when the torsional torque of the drive shaft 9 reverses direction. This torsional torque varies periodically corresponding to the natural vibration coefficient of the drive shaft 9. Therefore, the predetermined time can be set to half a cycle based on the natural vibration coefficient corresponding to the shape or elastic coefficient of the drive shaft 9.

[0042] Furthermore, if the anomaly determination unit 33 (described later) determines that there is an anomaly that the torque acting on the drive shaft 9 cannot be properly controlled, the rate setting unit 31 sets a reduction rate based on the characteristics of the motor 1 so that the auxiliary torque becomes zero. That is, when the torque acting on the drive shaft 9 can be properly controlled, the reduction rate is set so that the auxiliary torque is reduced to zero in a shorter time than the aforementioned predetermined time for reducing the auxiliary torque.

[0043] The motor control unit 32 controls the execution value of the auxiliary torque based on the auxiliary torque at the moment the parking lock mechanism 11 switches from the locked state to the released state, the reduction rate set by the rate setting unit 31, and the elapsed time since the parking lock mechanism 11 switched to the released state. That is, the instantaneous auxiliary torque of the motor 1 is calculated, and the torque of the motor 1 is controlled in a manner that yields the calculated auxiliary torque. Specifically, the instantaneous auxiliary torque is calculated by subtracting the product of the reduction rate and the elapsed time from the auxiliary torque at the moment the parking lock mechanism 11 switches from the locked state to the released state.

[0044] The anomaly determination unit 33 determines whether an anomaly has occurred that prevents normal control of the torque acting on the drive shaft 9. Specifically, for example, an anomaly is determined if the braking torque acting on the wheel 10 by the aforementioned braking device 14 or EPB 15 cannot be controlled, or if the ECU 21 fails to receive a signal related to the braking torque. That is, it determines whether a signal indicating a malfunction of the braking device 14 or EPB 15 has been input from the EPB-ECU 26 or B-ECU 27 to the ECU 21, or whether a communication failure has occurred between the EPB-ECU 26 or B-ECU 27 and the ECU 21. Furthermore, if an anomaly occurs that prevents normal control of the torque acting on the drive shaft 9, the anomaly determination unit 33 sets the anomaly determination flag to be on.

[0045] exist Figure 3 The diagram shows a flowchart illustrating an example of controlling the torque output from motor 1. Figure 3In the control example shown, firstly, it is determined whether the motor control execution flag is off (step S1). This motor control execution flag is activated when the drive shaft 9 twists to the extent that the vehicle Ve vibrates when the parking lock mechanism 11 is released. That is, the motor control execution flag is activated for example based on various conditions of drive shaft 9 twisting, such as the parking lock mechanism 11 being in the locked state, the braking torque acting on the wheel 10 from the parking lock mechanism 11 being in the locked state being less than a specified torque and the wheel 10 being able to rotate, and the tilt angle (absolute value) of the vehicle Ve in the pitch direction being greater than a specified angle.

[0046] If the determination in step S1 is affirmative because the motor control execution flag is off, the target value of the auxiliary torque based on motor 1 (hereinafter referred to as the target auxiliary torque) is set to "0" (step S2). Conversely, if the determination in step S1 is negative because the motor control execution flag is on, it is determined whether it is the moment when the motor control execution flag switches from off to on (step S3). This step S3 can be determined based on whether it was affirmatively determined in step S1 of the previous routine.

[0047] If the determination in step S3 is affirmative when the motor control execution flag switches from off to on, a target auxiliary torque based on the vehicle Ve's tilt angle is set (step S4). This step S4 is performed by the target torque setting unit 30. Specifically, by conducting prior experiments, a MAP is constructed that determines the target auxiliary torque corresponding to the vehicle Ve's tilt angle, and this MAP is stored in the ECU 21. The target auxiliary torque is determined based on the vehicle Ve's tilt angle corresponding to the acceleration detected by the acceleration sensor 22 and the MAP. Furthermore, the vehicle Ve's tilt angle is not limited to the tilt angle detected when the parking lock mechanism 11 is switched from the locked state to the unlocked state, but can also be the tilt angle detected when the parking lock mechanism 11 is set to the locked state for parking.

[0048] On the other hand, if it is not the moment when the motor control execution flag is switched from off to on, that is, if the determination is negative in step S3 because the motor control execution flag has been switched to on and the target auxiliary torque of motor 1 has been set, the target auxiliary torque of motor 1 is maintained at the previous value (step S5). That is, the target auxiliary torque of motor 1 is maintained after it is set when the motor control execution flag is switched to on.

[0049] After steps S2, S4, and S5, the rate of decrease in the auxiliary torque output from motor 1 is determined. Specifically, firstly, during the period when auxiliary torque is output from motor 1, it is determined whether an abnormality has occurred, such as ECU 21 failing to receive a signal related to the braking torque of braking device 14 or EPB 15. Specifically, the abnormality determination unit 33 determines whether the abnormality determination flag is set to on (step S6).

[0050] If the abnormality determination flag is on and a positive determination is made in step S6, the rate at which the auxiliary torque of motor 1 decreases is set to a maximum rate preset according to the characteristics of motor 1 (step S7). Conversely, if the abnormality determination flag is off and a negative determination is made in step S6, the rate at which the auxiliary torque decreases within a preset time period is set to correspond to the magnitude of the auxiliary torque at that moment (step S8). These steps S7 and S8 can be executed by the rate setting unit 31.

[0051] exist Figure 4 The diagram shows a timing graph illustrating the rate of decrease corresponding to the auxiliary torque. The solid line represents the change in the auxiliary torque and motor control execution flag when a relatively large target auxiliary torque is set due to the large tilt angle of the vehicle Ve. The dashed line represents the change in the auxiliary torque and motor control execution flag when a relatively small target auxiliary torque is set due to the small tilt angle of the vehicle Ve. The single-dotted line represents the change in the auxiliary torque and motor control execution flag when the parking lock mechanism 11 is released before the auxiliary torque reaches the target auxiliary torque.

[0052] exist Figure 4 In the example shown by the solid and dashed lines, at time t0, because the motor control execution flag is switched on, a target auxiliary torque is set, and the auxiliary torque begins to increase toward that target auxiliary torque. Furthermore, by increasing the auxiliary torque at a preset rate, the time at which the auxiliary torque reaches the target auxiliary torque varies depending on the magnitude of the target auxiliary torque.

[0053] Then, at time t1, the rate of reduction of the auxiliary torque is set by performing step S8 above by switching the parking lock mechanism 11 from the locked state to the released state. Specifically, in order to... Figure 4 The reduction rate is set so that the auxiliary torque becomes "0" at time t2. That is, regardless of the magnitude of the target auxiliary torque, the reduction rate is set based on the auxiliary torque at the moment when the parking lock mechanism 11 is in the released state.

[0054] In addition, such as Figure 4As shown by the dashed line, sometimes, immediately after the motor control execution flag is switched on (at time t3), before the auxiliary torque reaches the target auxiliary torque, the parking lock mechanism 11 switches from the locked state to the released state. In this case, the reduction rate is set so that the auxiliary torque at the moment the parking lock mechanism 11 switches from the locked state to the released state becomes "0" within a specified time.

[0055] Then, after steps S7 and S8, the execution value of the auxiliary torque is set (step S9), and the routine is temporarily terminated. Specifically, the execution value of the auxiliary torque is set by multiplying the reduction rate set in step S7 or S8 by the elapsed time by the auxiliary torque at the moment when the parking lock mechanism 11 switches from the locked state to the released state.

[0056] exist Figure 5 The diagram shows the process for execution. Figure 3 The timing diagram illustrates an example of the changes in the vehicle Ve's tilt angle, shift position, driving gear, motor control execution flag, speed processing flag, and auxiliary torque (execution value) under the control example shown. Additionally, in... Figure 5 The example given is the use of an instantaneous type of shifting device 24.

[0057] exist Figure 5 In the example shown, at time t10, with the parking gear (P) engaged, the vehicle Ve's tilt angle is above a predetermined angle. Simultaneously, the torsion determination flag is activated. On the other hand, since the shift lever 28 is in the standby position (Home), it is predicted that no shift to a driving gear will occur. Therefore, the motor control execution flag is deactivated.

[0058] The gear shifting operation begins at time t10. Specifically, the gear shifting operation involves changing the driving gear from the parking gear to the drive gear (D). In the example shown, the gear shift lever 28 is operated to the drive position via the neutral position (N) at time t12. Furthermore, at time t13, the driver releases the gear shift lever 28, and the shift position becomes the standby position.

[0059] By initiating the gear shift operation at time t10, it is predicted that the driving gear will be switched from parking to another driving gear, and therefore this is affirmatively determined in step S3 of the control example described above. As a result, the motor control execution flag is switched on, and the target auxiliary torque (dashed line) is set according to the vehicle's tilt angle Ve. Therefore, from time t11 onwards, the auxiliary torque of motor 1 gradually increases towards the target auxiliary torque. Figure 5 In the example shown, the actual auxiliary torque of motor 1 is increased to the target auxiliary torque at time t12.

[0060] exist Figure 5In the example shown, before time t14, the parking lock mechanism 11 is switched to the released state. Therefore, due to the reduced load on the torsional torque caused by the engagement of the parking gear 12 and the parking pawl 13, the remaining torque (the difference between the torsional torque and the auxiliary torque) is transmitted to the motor 1, causing the motor 1 to start rotating, and the motor control execution flag is switched off. As a result, at time t14, the target auxiliary torque (dashed line) becomes "0". Furthermore, at time t14, the anomaly detection flag remains off.

[0061] Therefore, a reduction rate corresponding to the magnitude of the auxiliary torque at time t14 is set, and the executed value of the auxiliary torque begins to decrease at this reduction rate. Furthermore, a rate processing flag used to determine the controlled value of the auxiliary torque based on the set reduction rate is switched on at time t14.

[0062] Then, at time t15, the auxiliary torque is switched to "0", and at time t16, the driving gear is switched to drive gear (D).

[0063] As described above, by setting the auxiliary torque to become "0" within a specified time and setting the rate of decrease of the auxiliary torque to correspond to the auxiliary torque when the parking lock mechanism 11 is switched to the released state, it is possible to stop the output of auxiliary torque before the direction of the torsional torque of the drive shaft 9 reverses when the parking lock mechanism 11 is released. In other words, the auxiliary torque can be made to decrease as the torsional torque of the drive shaft 9 decreases. Therefore, during the process of the decrease of the torsional torque of the drive shaft 9, the auxiliary torque that counteracts the torsional torque can be applied to the drive shaft 9 to suppress vibration. Furthermore, after the direction of the torsional torque of the drive shaft 9 reverses, the auxiliary torque is added to the torsional torque, which can suppress the increase in the amount of torsion of the drive shaft 9. As a result, the pulsating torsional torque of the drive shaft 9 can be rapidly attenuated. That is, the effect of reducing vehicle vibration can be improved.

[0064] Furthermore, the vehicle in the embodiments of the present invention is not limited to a vehicle in which each wheel is connected to a motor, but may also be a vehicle configured to transmit torque from one motor to a pair of front wheels or rear wheels or all wheels. It may also be a hybrid vehicle that, in addition to the motor, has an engine as a drive power source. Moreover, the structure connecting the motor 1 and the drive shaft 9, or the rotating parts that are prevented from rotating by the parking lock mechanism 11, are not limited to... Figure 1 The structure shown. Furthermore, the vehicle in the embodiments of the present invention may not have EPB15.

[0065] Symbol Explanation

[0066] 1, 16 - Motor; 2, 8 - Output shaft; 3, 6 - Drive gear; 4, 7 - Driven gear; 5 - Intermediate shaft; 9 - Drive shaft; 10 - Wheel; 11 - Parking lock mechanism; 12 - Parking lock gear; 13 - Parking pawl; 14 - Braking device; 15 - Electric parking brake (EPB); 17 - Housing; 18 - Mounting component; 19 - Body; 20 - Suspension device; 21 - Electronic control unit (ECU); 22 - Acceleration sensor; 23 - Rotary transformer; 24 - Shift device; 25 - Shift sensor; 26 - EPB-ECU; 27 - B-ECU; 28 - Shift lever; 29 - Switching determination unit; 30 - Target torque setting unit; 31 - Rate setting unit; 32 - Motor control unit; 33 - Abnormal determination unit; Ve - Vehicle.

Claims

1. A control device for a vehicle, the vehicle comprising: a drive shaft, one end of which is 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, which prevents rotation of a predetermined rotating component between the motor and the drive shaft, and an unlocked state, wherein when the parking lock mechanism is in the locked state, an auxiliary torque is output from the motor to counteract the torsional torque accompanying the torsion of the drive shaft, the control device for the vehicle being characterized in that... It has a controller for controlling the motor. The controller has: The switching determination unit determines that the parking lock mechanism has switched from the locked state to the released state; The rate setting unit sets the rate of decrease of the auxiliary torque so that the auxiliary torque becomes zero after a predetermined time has elapsed since the parking lock mechanism was switched to the released state; and The motor control unit controls the motor based on the auxiliary torque, the reduction rate, and the elapsed time from the moment the parking lock mechanism switches to the released state.

2. The vehicle control device according to claim 1, characterized in that, The specified time is a time set according to the natural vibration coefficient of the drive shaft.

3. The vehicle control device according to claim 2, characterized in that, The specified time is half the cycle time based on the natural vibration number of the drive shaft.

4. The vehicle control device according to claim 1, characterized in that, The rate setting unit includes the rate obtained by dividing the auxiliary torque at the moment when the parking lock mechanism is switched to the released state by the predetermined time.

5. The vehicle control device according to any one of claims 1 to 4, characterized in that, The controller also features: The anomaly detection unit determines that the torque acting on the drive shaft cannot be properly controlled due to an anomaly. When the rate setting unit determines that it cannot properly control the torque acting on the drive shaft, it sets the rate of decrease of the auxiliary torque so that the auxiliary torque becomes zero in a shorter time than the predetermined time.

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