JP2016117358A - Brake system control method and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake system control method that can keep brake force constant at pedal utmost tread force even when auxiliary force from negative pressure varies, and to provide a control device.SOLUTION: The brake system control method sets utmost wheel cylinder pressure 37 relative to the utmost pedal tread force and increases liquid pressure of a wheel cylinder 5 toward the utmost wheel cylinder pressure 37 by an ABS pump 6 when pedal tread force is larger than a full load point 34.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a control method and a control device for a brake system that brakes a wheel of a vehicle.

  As a brake system that brakes the wheel of a vehicle, a vacuum booster that assists the depressing force of the brake pedal with negative pressure, a master cylinder that generates hydraulic pressure according to the pedal depressing force, and hydraulic pressure from the master cylinder as wheel cylinder pressure One having a brake hydraulic circuit for transmission to a wheel cylinder is known.

  According to such a brake system, the depression force of the brake pedal can be assisted with a negative pressure force, and the load on the driver can be reduced.

  In the brake system described above, when the brake pedal is depressed to some extent, the assist force due to the negative pressure from the vacuum booster reaches the upper limit, and after the assist force due to the negative pressure reaches the upper limit, the brake force is increased only with the pedal effort. When the vehicle is heavy due to loading, etc., or when the driver is ineffective, there is a possibility that the braking force will be insufficient, so the pressure from the pump is used to assist the lack of braking force. There was also a brake system.

  In such a brake system, the brake pedal does not suddenly become heavy even after the auxiliary force due to the negative pressure reaches the upper limit, and it was possible to reliably prevent the brake force from being insufficient.

JP 09-30385 A JP-A-10-278765 JP 09-328069 A

  However, there is a problem that the braking force at the maximum pedal depression force is not constant if the uniform assist is provided even when the negative pressure changes.

  An object of the present invention is to provide a control method and a control device for a brake system that can keep a braking force at a preset maximum pedal depression force constant even when an assist force due to negative pressure changes.

  In order to achieve the above object, the present invention provides a brake pedal that is operated with a pedaling force, a vacuum booster that assists the pedaling force of the brake pedal with a negative pressure, and a hydraulic pressure that is connected to the vacuum booster according to the pedaling force. And a brake having an ABS pump for transmitting the hydraulic pressure from the master cylinder to the wheel cylinder as a wheel cylinder pressure and intermittently releasing the hydraulic pressure transmitted to the wheel cylinder when the wheel is locked. A hydraulic pressure circuit, the characteristic line of the wheel cylinder pressure with respect to the pedal depression force generated by the vacuum booster is supplemented by a negative pressure to increase the wheel cylinder pressure, and the total load without the assistance of the negative pressure A non-auxiliary line that rises from the point with the pedaling force. Brake system control for assisting the hydraulic pressure of the wheel cylinder using the hydraulic pressure of the ABS pump to raise the wheel cylinder pressure from the non-auxiliary line portion from the full load point of the auxiliary line portion when the cylinder pressure is insufficient In this method, a maximum wheel cylinder pressure with respect to a preset maximum pedal depression force is set, and when the pedal depression force is larger than a full load point, the hydraulic pressure of the wheel cylinder is directed to the maximum wheel cylinder pressure by the ABS pump. It is something to raise.

  According to the present invention, the braking force at the maximum pedal depression force can be kept constant even when the assisting force due to the negative pressure changes.

1 is an overall explanatory diagram of a brake control device according to an embodiment of the present invention. It is a circuit diagram of an anti-lock brake system with a braking force assist function. It is a circuit diagram of an anti-lock brake system with a braking force assist function during braking force assist. FIG. 3 is a circuit diagram of an anti-lock brake system with a braking force assist function in a state in which wheel cylinder pressure is loosened to prevent wheel lock. It is a circuit diagram of an anti-lock brake system with a braking force assist function in a state where wheel cylinder pressure is maintained. It is a diagram showing a pedal effort-wheel cylinder pressure characteristic line.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, the brake system 1 includes a brake pedal 2 that is operated by a pedaling force, a vacuum booster 3 that assists the pedaling force of the brake pedal 2 with negative pressure, and a liquid that is connected to the vacuum booster 3 according to the pedaling force. The master cylinder 4 that generates pressure, and the hydraulic pressure from the master cylinder 4 is transmitted to the wheel cylinder 5 as the wheel cylinder pressure, and the hydraulic pressure that is transmitted to the wheel cylinder 5 when the wheels FR, FL, RR, and RL are locked. And a brake hydraulic circuit 7 having an ABS pump 6 (see FIG. 2) for releasing the hydraulic pressure of the wheel cylinder 5 intermittently.

  The brake pedal 2 is supported so as to be swingable about a horizontal axis, and an input shaft 8 of a vacuum booster 3 is connected to the brake pedal 2.

  The vacuum booster 3 has an input side chamber and an output side chamber (not shown) that are partitioned by a diaphragm (not shown) and into which negative pressure is introduced, and an output of the vacuum booster 3 is obtained by introducing atmospheric pressure into the input side chamber. To help. A vacuum tank 10 is connected to the vacuum booster 3 through a negative pressure pipe 9. A negative pressure sensor 11 is provided in the negative pressure pipe 9. The negative pressure sensor 11 is connected to a controller 12 described later so that the controller 12 can acquire the pressure in the negative pressure pipe 9. Further, a vacuum pump 14 is connected to the vacuum tank 10 via a check valve 15.

  The master cylinder 4 is connected to the output side of the vacuum booster 3, and generates a hydraulic pressure by the force from the vacuum booster 3. A reservoir 16 for supplying hydraulic fluid into the master cylinder 4 is connected to the master cylinder 4.

  The wheel cylinder 5 is for braking the wheels FR, FL, RR, and RL of the vehicle, and generates a braking force according to the wheel cylinder pressure. In the figure, BT is a battery.

  As shown in FIGS. 2 to 5, the brake hydraulic circuit 7 brakes the first system 7 a for braking the left front wheel FL and the right front wheel FR of the vehicle, and the right rear wheel RR and the left rear wheel RL of the vehicle. To the second system 7b. The 1st system 7a and the 2nd system 7b are constituted similarly, and are controlled similarly.

  The first system 7a will be described. The description of the second system 7b is omitted, and the same reference numerals are given to the same configurations as those of the first system 7a.

  The first system 7 a includes a main hydraulic pressure supply line 17 that connects the master cylinder 4, a wheel cylinder 5 for the left front wheel FL, and a wheel cylinder 5 for the right front wheel FR, and a braking force connected to the main hydraulic pressure supply line 17. And an ABS circuit unit 18 with an assist function.

  The main hydraulic pressure supply line 17 is provided with a flow rate adjustment valve 19 that can be switched between a fully open mode and a flow rate adjustment mode, and is connected to a first bypass circuit 20 that bypasses the flow rate adjustment valve 19. The flow rate adjustment valve 19 has a check valve function for stopping the flow of hydraulic fluid from the master cylinder 4 side to the wheel cylinder 5 side in the flow rate adjustment mode. The first bypass 20 is provided with a first check valve 21 that stops the flow of hydraulic fluid from the wheel cylinder 5 side to the master cylinder 4 side. The first bypass 20 and the first check valve 21 are connected to the master cylinder 4 from the master cylinder 4 even when the flow adjustment valve 19 is in a state of reducing the flow rate when a large hydraulic pressure is generated in the master cylinder 4 due to sudden braking or the like. It functions to transmit the hydraulic pressure to the wheel cylinder 5 side. The main hydraulic pressure supply line 17 on the wheel cylinder 5 side of the flow rate adjusting valve 19 is provided with a main switching valve 22 that can be fully opened and closed, and a second bypass circuit 23 that bypasses the main switching valve 22 is connected. ing. The second bypass 23 is provided with a second check valve 24 that stops the flow of hydraulic fluid from the master cylinder 4 side to the wheel cylinder 5 side.

  The ABS circuit portion 18 with a braking force assist function is connected to the ABS pump 6 driven by the motor M and the main hydraulic pressure supply line 17 on the wheel cylinder 5 side of the main switching valve 22 and the suction side of the ABS pump 6. To the hydraulic pressure release line 25 for releasing the hydraulic pressure of the wheel cylinder 5 and the main hydraulic pressure supply line 17 connected to the discharge side of the ABS pump 6 and between the flow rate adjusting valve 19 and the main switching valve 22. Is connected to the main hydraulic pressure supply line 17 on the master cylinder 4 side and returned to the main hydraulic pressure supply line 17 on the master cylinder 4 side, and connected to the main hydraulic pressure supply line 17 on the master cylinder 4 side from the flow rate adjusting valve 19 and suction of the ABS pump 6 And a lead-in line 27 connected to the side. The hydraulic pressure release line 25 is provided with a sub switching valve 28 that can be fully opened and closed. The return line 26 is provided with a third check valve 29 and a throttle valve 30. The pull-in line 27 is provided with a valved liquid reservoir 31 that closes when the pressure exceeds a predetermined value.

  Further, a controller 12 for controlling these is connected to the motor M, the flow rate adjusting valve 19, the main switching valve 22, and the sub switching valve 28. The controller 12 is connected to a negative pressure sensor 11 that detects the negative pressure of the vacuum booster 3 and a speed sensor 41 that detects the rotational speeds of the wheels FR, FL, RR, and RL. The detected value is input. The controller 12 switches the presence / absence of hydraulic pressure assistance by the ABS pump 6 and adjusts the strength of assistance to supply the wheel cylinder 5 with hydraulic pressure corresponding to the pedal effort.

  FIG. 6 is a diagram showing the characteristics of the wheel cylinder pressure with respect to the pedal depression force generated by the vacuum booster 3 and the master cylinder 4.

  As shown in FIG. 6, the characteristic of the wheel cylinder pressure with respect to the pedal depression force generated by the vacuum booster 3 and the master cylinder 4 is represented by a pedal depression force-wheel cylinder pressure characteristic line (hereinafter, characteristic line) 32. The characteristic line 32 includes an auxiliary line portion 33 that is assisted by a negative pressure to increase the wheel cylinder pressure, and a non-auxiliary line portion 35 that rises with a pedal force from a full load point 34 at which the negative pressure assist reaches an upper limit.

  In addition, the horizontal broken line 36 in a figure shows full load point pressure. The upper broken line 36 indicates the upper limit full load point pressure, that is, the wheel cylinder pressure at the full load point 34 when the negative pressure from the vacuum tank 10 is sufficient when the brake pedal 2 starts to be depressed. A broken line 36 indicates the wheel cylinder pressure at the full load point 34 when the negative pressure is insufficient, such as after extensive use of the brake pedal 2.

  As shown in FIGS. 2 and 6, the control of the auxiliary line portion 33 fully opens the flow rate adjusting valve 19 and the main switching valve 22 and fully closes the sub switching valve 28. As a result, the master cylinder 4 and the wheel cylinder 5 are directly connected by the main hydraulic pressure supply line 17, and the hydraulic pressure release line 25 is closed, so that the hydraulic pressure from the master cylinder 4 is directly transmitted to the wheel cylinder 5. . At this time, since the pedal effort is assisted by the negative pressure from the vacuum booster 3, the wheel cylinder pressure does not become insufficient.

  Further, since the non-auxiliary line portion 35 is not assisted by the ABS pump 6, the rising angle from the full load point becomes loose, and the driver suddenly feels that the brake pedal 2 has become heavy, and the vehicle weight and driving Depending on the physical strength of the person, there was a risk of insufficient braking force.

  Therefore, the controller 12 according to the present embodiment, when the wheel cylinder pressure with respect to the pedal effort at the non-auxiliary line portion 35 is insufficient, determines the wheel cylinder pressure from the full load point 34 of the auxiliary line portion 33 to the non-auxiliary line portion 35. The hydraulic pressure of the wheel cylinder 5 is assisted by using the hydraulic pressure by the ABS pump 6 in order to raise it further. Specifically, the controller 12 has a storage unit (not shown) in which the maximum wheel cylinder pressure 37 with respect to the preset maximum pedal depression force is preset, and when the pedal depression force is greater than the full load point 34, the ABS 12 The hydraulic pressure of the wheel cylinder 5 is raised toward the maximum wheel cylinder pressure 37 by the pump 6. That is, the hydraulic pressure of the wheel cylinder 5 is increased so that the assisting line portion 38 representing the characteristic from the full load point 34 has the same inclination as the line 39 connecting the full load point 34 and the maximum wheel cylinder pressure 37. The maximum wheel cylinder pressure 37 is the amount of depression of the brake pedal 2 when the driver depresses the brake pedal 2 almost to the maximum in a normal driving state (when the pedal depression force reaches a value that is considered to be a practical maximum value). The braking effect (wheel cylinder pressure) on the vehicle is determined so as to match the driver's feeling. In the characteristic line 32, the maximum rising angle β from the full load point 34 to the maximum wheel cylinder pressure 37 is the auxiliary line portion. It is set to be gentler than the rising angle α of 33.

  Whether or not the full load point 34 has been reached is determined using the detection values of the negative pressure sensor 11 and the hydraulic pressure sensor 12.

  As shown in FIGS. 3 and 6, the assist line 38 is controlled by switching the flow rate adjusting valve 19 to the flow rate adjusting mode, opening the main switching valve 22 fully, closing the sub switching valve 28, and closing the ABS pump 6. While operating, the opening degree of the flow regulating valve 19 is adjusted so that the hydraulic pressure of the wheel cylinder 5 increases toward the maximum wheel cylinder pressure 37. For example, when the total load point 34 is on the upper broken line 36, the insufficient wheel cylinder pressure is relatively small, so that the flow rate adjustment valve 19 is opened from the open state so that the wheel cylinder pressure rises at a gentle angle γ. Squeeze with. Further, when the full load point 34 is on the lower broken line 36, the wheel cylinder pressure is largely insufficient, so that the flow rate adjusting valve 19 is relatively sudden from the open state so that the wheel cylinder pressure rises at a steep angle β. Squeeze at a slow pace. Since the maximum wheel cylinder pressure 37 is determined so that the braking effect on the depression amount of the brake pedal 2 matches the driver's feeling, the brake pedal 2 is depressed from the full load point 34 to the maximum wheel cylinder pressure 37. The braking effect can be matched to the driver's feeling.

  In addition, when the wheels FR, FL, RR, and RL are locked, the controller 12 operates the anti-lock brake system (hereinafter, ABS) with priority over the control of the hydraulic pressure supply according to the pedal depression force.

  As shown in FIGS. 4 and 5, when the controller 12 detects the lock of the wheels FR, FL, RR, RL from the detection value of the speed sensor 41, the controller 12 closes the main switching valve 22 and opens / closes the sub switching valve 28. Repeatedly, the ABS pump 6 is operated. At the moment when the sub switching valve 28 is opened as shown in FIG. 4, the pressure of the wheel cylinder 5 is released and the locks of the wheels FR, FL, RR, RL are released, and the sub switching valve 28 is closed as shown in FIG. At the moment, the pressure of the wheel cylinder 5 is maintained and the brake is applied. For this reason, it is possible to prevent a reduction in braking force and a deterioration in steering performance due to wheel lock.

  In this way, the maximum wheel cylinder pressure 37 with respect to the preset maximum pedal depression force is set, and when the pedal depression force is greater than the full load point 34, the hydraulic pressure of the wheel cylinder 5 is directed toward the maximum wheel cylinder pressure 37 by the ABS pump 6. Therefore, even if the assisting force due to the negative pressure changes, a constant braking force can be obtained with the preset maximum pedaling force. And the effect of the brake with respect to the depression amount of the brake pedal 2 can be matched with a driver | operator's sense, and braking of a vehicle can be performed smoothly with a favorable feeling. Furthermore, the feeling of braking can be adjusted to the driver's preference by rewriting the maximum wheel cylinder pressure 37 stored in the controller.

  Further, when assisting the hydraulic pressure of the wheel cylinder 5, the brake hydraulic pressure circuit 7 causes the hydraulic fluid from the ABS pump 6 to flow to the master cylinder 4 side through the flow rate adjusting valve 19, and the hydraulic pressure of the wheel cylinder 5 is maximized. Since the opening degree of the flow rate adjusting valve 19 is adjusted so as to increase toward the wheel cylinder pressure 37, the braking force after the auxiliary force due to the negative pressure reaches the upper limit can be reliably adjusted with a simple structure.

  Although the hydraulic pressure of the wheel cylinder 5 is increased by adjusting the opening degree of the flow rate adjusting valve 19, the hydraulic pressure of the wheel cylinder 5 may be increased by adjusting the capacity of the ABS pump 6.

DESCRIPTION OF SYMBOLS 1 Brake system 2 Brake pedal 3 Vacuum booster 4 Master cylinder 5 Wheel cylinder 6 ABS pump 7 Braking hydraulic circuit 12 Controller 32 Characteristic line 33 Auxiliary line part 34 Full load point 35 Non-auxiliary line part 37 Maximum wheel cylinder pressure

Claims (4)

A brake pedal operated by a pedaling force, a vacuum booster that assists the pedaling force of the brake pedal with a negative pressure, a master cylinder that is connected to the vacuum booster and generates a hydraulic pressure according to the pedaling force, and from the master cylinder The hydraulic pressure is transmitted to the wheel cylinder as the wheel cylinder pressure, and the brake hydraulic pressure circuit having an ABS pump that intermittently releases the hydraulic pressure transmitted to the wheel cylinder when the wheel is locked is generated by the vacuum booster. The characteristic line of the wheel cylinder pressure with respect to the pedal depression force that is applied is an auxiliary line part that increases the wheel cylinder pressure with the aid of negative pressure, and the non-auxiliary line that rises with the pedaling force above the full load point at which the negative pressure assistance reaches the upper limit When the wheel cylinder pressure is insufficient for the pedal effort at the non-auxiliary line , A method of controlling a brake system for assisting the hydraulic pressure of the wheel cylinder using the hydraulic pressure by the ABS pump to raise from the non-auxiliary line portion of the wheel cylinder pressure from the full-load point of the auxiliary line section,
The maximum wheel cylinder pressure with respect to the preset maximum pedal depression force is set, and when the pedal depression force is greater than the full load point, the hydraulic pressure of the wheel cylinder is increased toward the maximum wheel cylinder pressure by the ABS pump. Brake system control method.   When assisting the hydraulic pressure of the wheel cylinder, the braking hydraulic pressure circuit causes the hydraulic fluid from the ABS pump to flow to the master cylinder side via the flow rate adjusting valve, and the hydraulic pressure of the wheel cylinder is set to the maximum wheel cylinder pressure. The brake system control method according to claim 1, wherein the opening degree of the flow rate adjusting valve is adjusted so as to rise upward. A brake pedal operated by a pedaling force, a vacuum booster that assists the pedaling force of the brake pedal with a negative pressure, a master cylinder that is connected to the vacuum booster and generates a hydraulic pressure according to the pedaling force, and from the master cylinder A brake hydraulic pressure circuit having an ABS pump that transmits the hydraulic pressure as a wheel cylinder pressure to the wheel cylinder and intermittently releases the hydraulic pressure of the wheel cylinder to release the hydraulic pressure transmitted to the wheel cylinder when the wheel is locked. The characteristic line of the wheel cylinder pressure with respect to the pedal depression force generated by the vacuum booster includes an auxiliary line portion that is assisted by the negative pressure to increase the wheel cylinder pressure, and the full load at which the negative pressure assistance reaches the upper limit. It consists of a non-auxiliary line part that rises with a pedaling force greater than or equal to the point, and When the wheel cylinder pressure is insufficient, the brake system for assisting the hydraulic pressure of the wheel cylinder by using the hydraulic pressure by the ABS pump to increase the wheel cylinder pressure from the non-auxiliary line portion from the full load point of the auxiliary line portion A control device of
A controller for setting a maximum wheel cylinder pressure with respect to the maximum pedal depression force and increasing the hydraulic pressure of the wheel cylinder toward the maximum wheel cylinder pressure by the ABS pump when the pedal depression force is greater than a full load point; Brake system control device.   The brake hydraulic circuit has a flow rate adjusting valve that returns the hydraulic fluid from the ABS pump to the master cylinder side so that the flow rate can be adjusted when assisting the hydraulic pressure of the wheel cylinder. The brake system control device according to claim 3, wherein the opening degree of the flow rate adjusting valve is adjusted so that the pressure increases toward the maximum wheel cylinder pressure.

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