Vehicular control apparatus

Abstract

To provide a vehicular control apparatus capable of suppressing occurrence of a shock in the case of P-range of a shift range being disengaged.SOLUTION: An electronic control apparatus 90 of a vehicle 10 performs: controlling a foot brake 50 at first braking power Fbrk1 that is larger than braking power corresponding to a brake operating amount θbrk in a case where (a) the vehicle is determined to have stopped by the foot brake 50 on a given inclined road; (b) controlling the foot brake 50 at second braking power Fbrk2 that is larger than the first braking power Fbrk1 in a case where it is determined that there is an intention of parking after controlling the foot brake 50 at the first braking power Fbrk1, and change the shift range to the P-range; and (c) release the braking power of the foot brake 50 after an electric parking brake (EPB) 60 is switched to an operating state.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle including a foot brake that generates braking force according to a driver's brake operation amount and a parking brake.

Background Art

[0002] A control device for a vehicle including a foot brake that generates braking force according to a driver's brake operation amount and a parking brake is known. For example, the one described in Patent Document 1 is such a device. In the control device described in Patent Document 1, in order to suppress a shock that occurs when the P range of the shift range is released, the load applied to the parking gear is reduced by a drive motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the vehicle described in Patent Document 1, when starting off with the P range released, it is necessary to drive the drive motor, it is difficult to calculate the output torque of the drive motor required for shock reduction, and when the output torque is applied from the drive motor, unnatural behavior of the vehicle may occur. There are problems such as this.

[0005] The present invention has been made based on the above circumstances, and an object thereof is to provide a control device for a vehicle that can suppress the occurrence of shock when the P range of the shift range is released.

Means for Solving the Problems

[0006] The gist of the present invention is a control device for a vehicle including a foot brake that generates braking force according to a driver's brake operation amount and a parking brake, wherein: (a) when it is determined that the vehicle has stopped on a predetermined inclined road by the foot brake, the foot brake is controlled to a predetermined first braking force greater than the braking force corresponding to the brake operation amount; (b) when it is determined that there is an intention to park after the foot brake is controlled to the first braking force, the foot brake is controlled to a predetermined second braking force greater than the first braking force and the shift range is switched to the P range; and (c) after the parking brake is switched to the operating state, the braking force of the foot brake is released.

Effect of the Invention

[0007] According to the control device for a vehicle of the present invention, (a) when it is determined that the vehicle has stopped on a predetermined inclined road by the foot brake, the foot brake is controlled to a predetermined first braking force greater than the braking force corresponding to the brake operation amount; (b) when it is determined that there is an intention to park after the foot brake is controlled to the first braking force, the foot brake is controlled to a predetermined second braking force greater than the first braking force and the shift range is switched to the P range; and (c) after the parking brake is switched to the operating state, the braking force of the foot brake is released. In this way, since the braking force of the foot brake is released after the parking brake is switched to the operating state, the load applied to the parking gear is suppressed, and the generation of shock when the P range of the shift range is released is suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments, the drawings are appropriately simplified or deformed, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

Embodiment

[0010] FIG. 1 is a schematic configuration diagram of a vehicle 10 including an electronic control device 90 according to an embodiment of the present invention, and is a functional block diagram showing the main parts of control functions for various controls in the vehicle 10.

[0011] The vehicle 10 includes a power source 12 for traveling, a pair of drive wheels 14, and a power transmission device 16 provided in the power transmission path between the power source 12 and the pair of drive wheels 14. The power source 12 is a well-known power source such as an engine or an electric motor. The power transmission device 16 includes, for example, an automatic transmission and a differential 18. The power transmission device 16 transmits the power transmitted from the power source 12 to the pair of drive wheels 14 via the differential 18.

[0012] The vehicle 10 is provided with a foot brake 50 (hereinafter simply referred to as "brake 50") and an electric parking brake 60 (hereinafter referred to as "EPB 60"). The brake 50 is a braking device that applies a braking force corresponding to the depression force of the brake pedal 42 by the driver, that is, the brake operation amount θbrk [%] representing the deceleration operation amount required by the driver, to a pair of drive wheels 14 and a pair of driven wheels (not shown). The brake 50 includes a brake pedal 42, a brake master cylinder 52 that generates a master pressure Pbm [kPa] corresponding to the brake operation amount θbrk, a brake body 70 provided on each of the pair of drive wheels 14 that generates a braking force proportional to the master pressure Pbm, and a hydraulic control unit 54 that can adjust the master pressure Pbm. The EPB 60 is a well-known electric parking brake and corresponds to the "parking brake" in the present invention. For example, when the EPB motor 62 is rotationally driven and a pair of cables 66 are pulled in via the pulling device 64, the brake body 70 provided on the pair of drive wheels 14 operates and a braking force is applied to the vehicle 10, that is, the EPB 60 is in an operating state. When the EPB motor 62 rotates to a predetermined position, the pulling device 64 is configured to mechanically hold the tension of the pair of cables 66. When the EPB motor 62 is rotationally driven in the reverse direction, the operation of the brake body 70 by the EPB 60 is released, that is, the EPB 60 is in a non-operating state. In this embodiment, the brake body 70 is shared by the brake 50 and the EPB 60 for the pair of drive wheels 14, but a non-sharing mode may also be used.

[0013] The shift operation device 30 employs a so-called shift-by-wire system. The shift operation device 30 includes, for example, a shift lever 32 and a P switch 34. Both the shift lever 32 and the P switch 34 return to their initial positions when not operated by the driver. The shift range includes, for example, a well-known R range (= reverse driving range), N range (= neutral range), D range (= forward driving range), B range (= decelerated forward driving range), and P range (= parking range).

[0014] The operating positions of the shift lever 32 are, for example, the positions of H, R, N, D, and B. The H position is the initial position (= home position) of the shift lever 32. The R, N, D, and B positions are the operating positions for selecting the R range, N range, D range, and B range, respectively. The P switch 34 is, for example, a momentary push-button switch. When the P switch 34 is pressed, the P range is selected. The P range is a shift range in which the vehicle 10 is in a neutral state and a pair of drive wheels 14 are mechanically fixed so as not to rotate. In the shift range, the R range, D range, and B range are "driving ranges", and the N range and P range are "non-driving ranges".

[0015] The parking lock mechanism 20 has a well-known configuration including a parking gear 20a that rotates in conjunction with a pair of drive wheels 14, a parking lock pole 20b that can be moved closer to and away from the parking gear 20a by being rotated around a single axis, and an actuator 22 (for example, a step motor) that controls the approach and separation of the parking lock pole 20b. The operating positions of the parking lock mechanism 20 include a lock position where the claw portion of the parking lock pole 20b is moved closer so as to mesh with the parking gear 20a, and a non-lock position where the claw portion is moved away so as not to mesh with the parking gear 20a. When the shift range is switched to a non-P range, the operating position of the parking lock mechanism 20 is controlled to the non-lock position. When the driver presses the P switch 34 and the operating position of the parking lock mechanism 20 is controlled to the lock position, it is assumed that the shift range has been switched to the P range, and the indicator 38 is lit to indicate that it is the P range.

[0016] The electronic control unit 90 is configured to include, for example, a so-called microcomputer, and performs signal processing according to a program stored in advance.

[0017] Various signals (such as the lever position signal POSlev, the P-switch signal Psw, the accelerator opening θacc [%] representing the amount of acceleration operation required by the driver, the brake operation amount θbrk representing the amount of deceleration operation required by the driver, the vehicle speed V [km / h], the road surface gradient angle θrd [deg], the actuator rotation angle POSact [deg] representing the rotational position of the actuator 22, etc.) based on the detection values from various sensors and the like (such as the lever position sensor 36, the P-switch 34, the accelerator opening sensor 80, the brake operation amount sensor 82, the vehicle speed sensor 84, the gradient angle sensor 86, the rotation angle sensor 88, etc.) provided in the vehicle 10 are respectively input to the electronic control device 90. Various command signals (such as the actuator control signal Sact for rotationally controlling the actuator 22, the master pressure control signal Sbm for controlling the braking force by the brake 50 via the hydraulic control unit 54, the EPB control signal Sepb for controlling the operating state of the EPB 60, the indicator signal Sindi for indicating that the shift range is the P range, etc.) are respectively output from the electronic control device 90 to each device (such as the actuator 22, the hydraulic control unit 54, the EPB motor 62, the indicator 38, etc.) provided in the vehicle 10.

[0018] The electronic control device 90 functionally includes a stop determination unit 90a, a slope road determination unit 90b, a parking intention determination unit 90c, a master pressure control unit 90d, a range control unit 90e, and an EPB control unit 90f.

[0019] The stop determination unit 90a determines whether the vehicle is in a stopped state based on the vehicle speed V and the brake operation amount θbrk. That is, it is determined whether the vehicle is stopped by the brake 50.

[0020] The slope determination unit 90b determines whether a given slope is a slope where the absolute value of the road surface gradient angle θrd exceeds the angle determination value θrd_jdg. The gradient angle θrd is the angle between the road surface and the horizontal plane in the driving direction. For example, it is zero on a flat road, a positive value on an uphill road, and a negative value on a downhill road. The angle determination value θrd_jdg is a predetermined determination value determined experimentally or by design to determine whether a slope where hill-hold control needs to be executed exists.

[0021] The master pressure control unit 90d can adjust the master pressure Pbm via the hydraulic control unit 54. That is, the master pressure control unit 90d can make the braking force of the brake 50 (hereinafter referred to as the "brake braking force") different from that corresponding to the brake operation amount θbrk. The master pressure control unit 90d executes hill-hold control to prevent the vehicle 10 from moving backward on a slope, for example, an uphill road, regardless of the brake operation. There are semi-actuation control and full-actuation control for hill-hold control. In semi-actuation control, the master pressure Pbm is controlled to a pressure value P1 higher than the pressure value corresponding to the brake operation amount θbrk. The pressure value P1 is a predetermined pressure value determined experimentally or by design that can prevent the vehicle 10 from slipping down when switching from the stepping operation of the brake pedal 42 to the stepping operation of the accelerator pedal 40 on a slope and can release the brake braking force without the driver feeling discomfort during restart. In semi-actuation control, the brake braking force is controlled to a first braking force Fbrk1 [N] greater than that corresponding to the brake operation amount θbrk. In full-actuation control, it is controlled to a maximum pressure value Pmax higher than the pressure value P1, which is the master pressure Pbm in semi-actuation control. The maximum pressure value Pmax is a predetermined pressure value determined experimentally or by design that can more reliably prevent the vehicle 10 from slipping down than semi-actuation control. In full-actuation control, the brake braking force is controlled to a second braking force Fbrk2 [N] greater than the first braking force Fbrk1.

[0022] FIG. 2 shows an example of the relationship between the road surface inclination angle θrd during parking and the master pressure Pbm. The minimum pressure value Pmin is the minimum value of the master pressure Pbm. The pressure value P0 is the master pressure Pbm required to prevent the vehicle 10 from slipping due to the brake 50. The pressure value P1 is the master pressure Pbm in the semi-actuation control. The maximum pressure value Pmax is the maximum value of the master pressure Pbm and is the master pressure Pbm in the full-actuation control.

[0023] In FIG. 2(a), as the absolute value of the road surface inclination angle θrd increases, the pressure values P0 and P1 are set to increase. When the absolute values of the road surface inclination angles θrd are the same, the pressure values P0 and P1 are set to the same values respectively. The pressure value P0 may be set to change according to the vehicle weight and road surface conditions. On a flat road, the pressure value P1 is set higher than the pressure value P0. The pressure value P1 is set to be the pressure value P0 multiplied by a constant value k (k > 1, k < Pmax / P0). FIG. 2(b) is substantially the same as FIG. 2(a), but in FIG. 2(b), (i) the pressure values P1 and P0 are set to the same value on a flat road, and (ii) the pressure value P1 is set higher in the case of an uphill road than in the case of a downhill road compared to (ii) (= the constant value k is larger in the case of an uphill road than in the case of a downhill road). Due to (ii), the release of the braking force is quickly performed during forward start on a downhill road, so the discomfort felt by the driver is suppressed.

[0024] Returning to FIG. 1. After the master pressure control unit 90d controls the brake braking force to the first braking force Fbrk1, the parking intention determination unit 90c determines whether the driver has the intention to park. For example, when the accelerator opening θacc is a zero value and the shift range is not the driving range, it is determined that there is an intention to park.

[0025] When it is determined that there is an intention to park after the brake braking force is controlled to the first braking force Fbrk1, the master pressure control unit 90d controls the brake braking force to a second braking force Fbrk2 that is greater than the first braking force Fbrk1, the range control unit 90e switches the parking lock mechanism 20 to the operating state, and the EPB control unit 90f switches the EPB 60 to the operating state.

[0026] After the EPB60 switches to the operating state, the master pressure control unit 90d releases the braking force.

[0027] FIG. 3 is an example of a flowchart for explaining the control operation of the electronic control device 90 shown in FIG. 1. The flowchart of FIG. 3 is repeatedly executed when the vehicle 10 is in an operable state.

[0028] First, it is determined in S10 whether the vehicle is in a stopped state. If the determination in S10 is YES, it is determined in S20 whether the brake is in the on state where the brake operation amount θbrk exceeds the zero value. If the determination in S20 is YES, it is determined in S30 whether the absolute value of the pitch angle θrd exceeds the angle determination value θrd_jdg. If the determination in S30 is YES, semi-operation control is executed in S40, and it is determined in S50 whether the accelerator opening θacc is not zero. If the determination in S50 is YES, the execution of the semi-operation control is cancelled in S120. If any of the determinations in S10 to S30 is NO and after the execution of S120, all return.

[0029] If the determination in S50 is NO, it is determined in S60 whether the shift range is not the driving range. If the determination in S60 is YES, full-operation control is executed in S70, the parking lock mechanism 20 is set to the operating state in S80, and it is determined in S90 whether it is in the P range state. If the determination in S90 is YES, the EPB60 is set to the operating state in S100, the execution of the hill-hold control is cancelled in S110, and it ends after the execution of S110. If the determinations in S60 and S90 are NO, S40 is executed again in both cases.

[0030] FIG. 4 is an example of a time chart when the flowchart of FIG. 3 is executed. FIG. 4 shows a case where the vehicle 10 decelerates due to the depression operation of the brake pedal 42 and comes to a stop on a predetermined slope at time t1. When the vehicle comes to a stop at time t1, the master pressure Pbm is increased from the pressure value corresponding to the brake operation amount θbrk to the pressure value P1, and semi-actuation control is executed. In FIG. 4, the case where the P switch 34 is pressed and parked at time t2 is shown by a solid line, and the case where the accelerator is operated and the vehicle resumes at time t2 is shown by a broken line.

[0031] Hereinafter, the case of parking (= example of solid line) will be described. When the P switch 34 is pressed at time t2 while the depression operation of the brake pedal 42 is continued, it is considered that the driver has the intention to park. Therefore, at time t2, the master pressure Pbm is increased from the pressure value P1 to the maximum pressure value Pmax, and full-actuation control is executed. At time t3, the EPB 60 is switched from the non-operating state to the operating state, and at time t4, the master pressure Pbm is decreased from the maximum pressure value Pmax to the pressure value Pepb according to the operating state of the EPB 60. Time t3 is the time after full-actuation control is executed, and time t4 is the time after the EPB 60 is switched to the operating state.

[0032] Hereinafter, the case of resuming (= example of broken line) will be described. When the brake pedal 42 is released a little before time t2 and the accelerator pedal 40 is depressed at time t2, it is considered that the driver has no intention to park. Therefore, at time t2, the master pressure Pbm is decreased from the pressure value P1 to the minimum pressure value Pmin, and the execution of semi-actuation control is cancelled. After time t2, for example, power based on the accelerator opening θacc and the vehicle speed V is transmitted to the pair of drive wheels 14, and the vehicle speed V is increased.

[0033] According to this embodiment, (a) when it is determined that the vehicle has stopped by the brake 50 on a predetermined slope, the braking force is set to the first braking force Fbrk1 which is greater than that corresponding to the brake operation amount θbrk, and (b) when it is determined that there is an intention to park after the braking force is set to the first braking force Fbrk1, the braking force is set to the second braking force Fbrk2 which is greater than the first braking force Fbrk1 and the shift range is switched to the P range. After the shift range is switched to the P range, the EPB 60 is switched to the operating state, and (c) after the EPB 60 is switched to the operating state, the braking force is released. In this way, since the braking force is released after the EPB 60 is switched to the operating state, the load applied to the parking gear 20a is suppressed, so that the generation of shock when the P range of the shift range is released is suppressed.

[0034] Note that the above are the embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art without departing from the spirit thereof.

[0035] In the above-described embodiment, the operation for switching the parking lock mechanism 20 to the operating state was executed by the P switch 34 of the shift-by-wire system, but it is not necessarily limited to this. For example, regardless of whether it is a shift-by-wire system or not, it may be an operation by a button type, a lever type, or a screen operation type such as a liquid crystal.

[0036] In the above-described embodiment, the brake body 70 that generates the braking force by the EPB 60 was provided on each of the pair of drive wheels 14, but it is not limited to this and may be provided on each of the pair of driven wheels.

Explanation of Reference Numerals

[0037] 10: Vehicle, 50: Foot Brake, 60: Electric Parking Brake (Parking Brake), 90: Electronic Control Unit (Control Unit), Fbrk1: First Braking Force, Fbrk2: Second Braking Force, θbrk: Brake Operation Amount

Claims

【Claim 1】 A control device for a vehicle comprising a foot brake that generates braking force according to the driver's brake operation amount and a parking brake, wherein: When it is determined that the vehicle has stopped by the foot brake on a predetermined inclined road, the foot brake is controlled to a predetermined first braking force greater than the braking force according to the brake operation amount; When it is determined that there is an intention to park after the foot brake is controlled to the first braking force, the foot brake is controlled to a predetermined second braking force greater than the first braking force and the shift range is switched to the P range; After the parking brake is switched to the operating state, the braking force of the foot brake is released. A vehicle control device characterized by the above.

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