Controller of vehicular parking lock mechanism

Abstract

To provide a controller of a vehicular parking lock mechanism which can decrease operation frequency of the parking lock mechanism.SOLUTION: When inclination of a road surface where a vehicle 10 is positioned is a prescribed value or less that is relatively flat, an electric parking brake 30 is sufficient to lock the vehicle 10 and activation of a parking lock mechanism 62 is not necessary, the parking lock mechanism 62 is not activated when a P switch 56 is operated. Thereby, operation frequency of the parking lock mechanism can be decreased.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a parking lock mechanism for a vehicle, and relates to the control of a vehicle equipped with a parking lock mechanism of a shift-by-wire system and an electric parking brake.

Background Art

[0002] In a vehicle equipped with a parking lock mechanism of a shift-by-wire system (SBW system) driven by an actuator operated by an electrical parking lock operation signal, for example, when a request to switch from ignition on to ignition off or an operation of a parking lock switch by a driver causes an operation request for the parking lock mechanism, control is performed to operate the parking lock mechanism when predetermined vehicle stop conditions such as the vehicle speed being lower than a predetermined value are satisfied. For example, the vehicle control device of Patent Document 1 is like this.

[0003] In a vehicle equipped with the above-described parking lock mechanism of the shift-by-wire system and an electric parking brake, usually, both the parking lock mechanism and the electric parking brake are operated in conjunction with the operation of a parking lock (P) switch. Thereby, for example, the reliability when fixing the vehicle on a steep slope is enhanced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, like parking on a flat road, it may sometimes be sufficient to fix the vehicle even if both the parking lock mechanism of the shift-by-wire system and the electric parking brake do not operate. In this case, for example, if the electric parking brake operates, there is no need to operate the parking lock mechanism, and there is a disadvantage that the operation frequency of the parking lock mechanism is unnecessarily increased.

[0006] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a control device for a vehicle parking lock mechanism that can reduce the operation frequency of the parking lock mechanism.

Means for Solving the Problems

[0007] The gist of the present invention is as follows: (a) In a vehicle equipped with a parking lock mechanism actuated by an actuator and an electric parking brake, a control device for a vehicle parking device that actuates the parking lock mechanism and the electric parking brake in response to an operation of a parking lock operation switch to fix the vehicle, and (b) when the road surface gradient is equal to or less than a predetermined value, not actuating the parking lock mechanism.

Effects of the Invention

[0008] According to the control device for a vehicle parking device of the present invention, when the road surface gradient is equal to or less than a predetermined value, the parking lock mechanism is not actuated, so that the operation frequency of the parking lock mechanism can be reduced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

Example

[0011] In FIG. 1, the power generated by the engine 16 is input to the automatic transmission 12 via the torque converter 14, and is transmitted from the output shaft 20 of the automatic transmission 12 to the left and right drive wheels 28 via the differential gear device 24 and a pair of axles 26. Hereinafter, an example of the case where the control device of the present invention is applied to a vehicle equipped with an engine as a driving power source will be described. However, the vehicle control device of the present invention can also be applied to other types of vehicles such as a hybrid vehicle equipped with an engine and an electric motor as driving power sources, or an electric vehicle equipped with only an electric motor as a driving power source. Further, the electronic control device 70 corresponds to the control device of the present invention.

[0012] The electronic control device 70 is configured to include a plurality of so-called microcomputers, and performs signal processing according to a program stored in advance, thereby performing drive control of the engine 16, the torque converter 14, and the automatic transmission 12, etc., shift position and parking lock switching control of the shift switching mechanism 34 using the shift-by-wire method, operation control of the electric parking brake (EPB) 30, operation of the vehicle power supply 68, etc. The electronic control device 70 functions as a control device for the parking lock mechanism 62 described later.

[0013] The electronic control unit 70 is supplied with, for example, a signal representing the engine rotational speed Ne (rpm) which is the rotational speed of the engine 16 detected by the engine rotational speed sensor 40, a signal representing the output rotational speed Nout (rpm) which is the rotational speed of an output gear (not shown) corresponding to the vehicle speed V detected by the vehicle speed sensor 42, the turbine rotational speed Nt (rpm) which is the rotational speed of the turbine shaft of the torque converter 14 detected by the turbine rotational speed sensor 44, a signal representing the accelerator opening Acc (%) which is the operation amount of an accelerator pedal (not shown) by the driver detected by the accelerator opening sensor 46, a brake operation signal Bon indicating the operation of the brake pedal detected by the brake switch 48, an operation signal Ig of the ignition switch (hereinafter referred to as IG-SW) 50, a signal Psh representing the shift position (operation position) of the shift lever 54 detected by the shift position sensor 52 constituting the shift operation device 60, and a P lock signal Pon from a parking lock operation switch (hereinafter referred to as P switch) 56 for operating the parking lock mechanism 62 shown in FIG. 2 for locking the drive wheels 28, a signal representing the longitudinal acceleration (road surface gradient) G detected by the acceleration sensor 58, and the like, respectively.

[0014] Further, the electronic control unit 70 outputs, for example, an engine output command signal Se for commanding the operation of the engine 16, a hydraulic pressure control command signal Sp for controlling the hydraulic pressure to the automatic transmission 12, a shift command signal Ss for instructing a shift range change to the shift change mechanism 34 or a locking operation of the parking lock mechanism 62, a brake command signal Sb for controlling the operation of the brake actuator 36 for operating the electric parking brake 30 which is a drum brake for braking the drive wheels 28, a power supply command signal Sba for controlling the vehicle power supply, and the like, respectively.

[0015] FIG. 2 is a perspective view showing a shift switching mechanism 34 composed of a shift range switching device 64 for switching the shift range of the automatic transmission 12 and a parking lock mechanism 62 for fixing the output shaft 20 of the automatic transmission 12 in a non-rotatable state. The shift switching mechanism 34 constitutes a shift-by-wire system that selects a shift range based on a shift position signal Psh, which is an output signal from the shift operation device 60.

[0016] The shift range switching device 64 of the shift switching mechanism 34 is an actuator that is operated based on a shift command signal Ss for instructing the operation of shift range switching or parking lock output from the electronic control device 70 based on the shift operation of the shift operation device 60 or the operation of the P switch 56. The shift range switching device 64 includes a step motor 110, a shaft 112 connected to the output shaft of the step motor 110 via, for example, a reduction gear device, and a plate-shaped detent plate 114 fixed to the shaft 112 and engaged with the spool valve element 104 of the valve 102. The detent plate 114 is rotated to any one of a plurality of rotational positions corresponding to a plurality of moving positions of the spool valve element 104 preset according to each shift range, for example, P, R, N, D. The operating position of the step motor 110, that is, the rotation angle of the rotor of the step motor 110, is detected by the rotary encoder 116.

[0017] The detent plate 114 includes a spool valve engaging rod 118 that engages with the spool valve element 104 in the axial direction (moving direction) of the spool valve element 104. When the detent plate 114 is rotated around the axis of the shaft 112, the spool valve element 104 is moved in the axial direction of the spool valve element 104 by the spool valve engaging rod 118 according to the rotation position.

[0018] Also, an engagement roller 124 rotatably supported at the tip of a leaf spring 122 with its base end fixed is in contact with a cam surface 120 of an outer peripheral edge portion located above the detent plate 114. This leaf spring 122 biases the engagement roller 124 toward the cam surface 120 with a predetermined pressing force. As a result, when the engagement roller 124 drops into any one of a plurality of recesses corresponding to P, R, N, and D formed in the cam surface 120, the detent plate 114 is positioned at any one of the plurality of rotational positions, and the spool valve element 104 is positioned at any one of a plurality of preset moving positions according to each shift range.

[0019] The parking lock mechanism 62 of the shift switching mechanism 34 includes a parking gear 108 connected to the output shaft 20 of the automatic transmission 12, a parking lock pole 126 that can approach and separate from the parking gear 108 by being rotated around a single axis, and has a claw portion 128 that meshes with the parking gear 108 when approaching the parking gear 108, and the output shaft 20 is fixed so as not to rotate by meshing the claw portion 128 with the parking gear 108, a parking rod 132 through which a tapered member 130 engaged with the parking lock pole 126 is inserted and supports the tapered member 130 at one end, and a spring 134 that biases the tapered member 130 toward its smaller diameter side. The other end of the parking rod 132 is connected to the lower end of the detent plate 114, and the tapered member 130 is configured to be moved toward the smaller diameter side when the detent plate 114 is rotated to the P position.

[0020] Figure 2 shows a state where the detent plate 114 is positioned at a rotational position corresponding to the P range. In this state, the rotation of the output shaft 20 is blocked by the engagement of the claw portion 128 of the parking lock pole 126 with the parking gear 108. From this state, when the shaft 112 is rotated in the direction of arrow A shown in Figure 2, the spool valve element 104 is moved in the direction of arrow B and positioned in a shift range other than P, that is, a shift range corresponding to a non-lock position. Also, when the parking lock pole 126 is moved in the direction of arrow D and the claw portion 128 is rotated to a position where it does not engage with the parking gear 108, the lock of the output shaft 20 is released.

[0021] The electric parking brake 30 is a friction brake that brakes the drive wheel 28 by pressing a lining, which is a friction material, against the inside of a brake drum (not shown) that rotates together with the drive wheel 28 by the force of an electric parking brake actuator 36 operated by the motor 38 in FIG. 1. Note that the electric parking brake 30 may be any electric parking brake that brakes the drive wheel 28, such as a disc brake.

[0022] Returning to FIG. 1, a block diagram for explaining the main part of the control function of the electronic control unit 70 is shown in the electronic control unit 70. The electronic control unit 70 is functionally configured to include a vehicle power supply control unit 72, a parking lock mechanism control unit 74 that controls the parking lock mechanism 62, and an electric parking brake control unit 76 that controls the electric parking brake 30.

[0023] The vehicle power supply control unit 72 determines the operation of the IG-SW 50 by the driver based on the IG-SW operation signal Ig from the IG-SW 50, and controls the connection of the vehicle power supply 68 such as the battery according to the determination.

[0024] The parking lock mechanism control unit 74 controls the change of the shift position and the execution of the parking lock of the parking lock mechanism 62 based on the shift position signal Psh from the shift position sensor 52 or the P switch signal Pon from the P switch 56. Further, the parking lock mechanism control unit 74 notifies other control units of the state of the parking lock mechanism 62, for example, whether it is in the locked state or the state where the locked state is released, at a predetermined timing. The parking lock mechanism control unit 74 preferentially operates the electric parking brake 30 among the electric parking brake 30 and the parking lock mechanism 62 in response to the shift command signal Ss instructing the operation of the parking lock mechanism 62 to fix the vehicle 10. When the road surface gradient obtained from the longitudinal and lateral accelerations G exceeds a predetermined value, that is, in the case of a steep gradient, while operating the parking lock mechanism 62, when the road surface gradient obtained from the longitudinal and lateral accelerations G is equal to or less than the predetermined value, the parking lock mechanism 62 is not operated in order to reduce the operation frequency of the parking lock mechanism 62.

[0025] The electric parking brake control unit 76 determines the operation of the electric parking brake 30 based on the P switch signal Pon from the P switch 56, and controls the operation of the brake actuator 36 based on the determination. The electric parking brake control unit 76 maintains the operation of the electric parking brake 30 even when the operation of the parking lock mechanism 62 is not performed based on the road surface gradient being equal to or less than a predetermined value.

[0026] Figure 3 is a flowchart for explaining the main part of a control operation example of the electronic control device 70. In Figure 3, at step S1 (hereinafter, steps are omitted), it is determined whether the P switch 56 has been operated. If the determination at S1 is negative, this routine is terminated. However, if it is positive, at S2, it is determined whether the electric parking brake 30 is operating. If the determination at S2 is negative, the parking lock mechanism 62 is actuated at S4. However, if it is positive, at S3, it is determined whether the operation of the parking lock mechanism 62 is unnecessary due to reasons such as the road surface being flat or the wheels hitting a stopper. If the determination at S3 is negative, since it is a steep slope or the like, the parking lock mechanism 62 is actuated at S4. However, if it is positive, at S5, the parking lock mechanism 62 is deactivated.

[0027] Figure 4 is a flowchart for explaining the main part of another control operation example of the electronic control device 70. In Figure 4, at S11, it is determined whether the P switch 56 has been operated. If the determination at S11 is negative, this routine is terminated. However, if it is positive, at S12, it is determined whether the main power supply is turned on (Ready-ON state) by operating the power-on switch. If the determination at S12 is negative, the parking lock mechanism 62 is actuated at S15. However, if it is positive, at S13, it is determined whether the electric parking brake 30 is operating. If the determination at S13 is negative, the parking lock mechanism 62 is actuated at S15. However, if it is positive, at S14, it is determined whether the road surface gradient is equal to or less than a predetermined value. If the determination at S14 is negative, since it is a steep slope, the parking lock mechanism 62 is actuated at S15. However, if it is positive, at S16, the parking lock mechanism 62 is deactivated.

[0028] According to the above-described electronic control device 70, when the gradient of the road surface on which the vehicle 10 is located is relatively flat and below a predetermined value, the electric parking brake 30 is sufficient to fix the vehicle 10, and it is not necessary to operate the parking lock mechanism 62. Therefore, even if the P switch 56 is operated, the parking lock mechanism 62 is deactivated. As a result, the operating frequency of the parking lock mechanism 62 can be reduced. In this way, when the operating frequency of the parking lock mechanism 62 is reduced, the operating durability target value of the parking lock mechanism 62 is relaxed, and the step motor (actuator) 110 can be miniaturized and the cost can be reduced.

[0029] As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is also applicable to other aspects.

[0030] The vehicle 10 in the above-described embodiment was a vehicle provided with the engine 16 as a drive source, but it may be a BEV vehicle provided with an electric motor as a drive source, an HEV vehicle provided with an engine and an electric motor as drive sources, or the like.

[0031] Note that the above description is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Description of Reference Numerals

[0032] 10: Vehicle, 30: Electric parking brake, 34: Shift switching mechanism, 56: P switch (parking lock operation switch), 60: Shift operation device, 62: Parking lock mechanism, 70: Electronic control device (control device), 110: Step motor (actuator)

Claims

【Claim 1】 In a vehicle equipped with a parking lock mechanism operated by an actuator and an electric parking brake, a control device for a vehicle parking lock mechanism that operates the parking lock mechanism and the electric parking brake in response to an operation of a parking lock operation switch to fix the vehicle, when the road surface gradient is equal to or less than a predetermined value, the parking lock mechanism is not operated A control device for a vehicle parking lock mechanism, characterized by the above.

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