JP4233730B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a brake fluid pressure control device for a vehicle that can cause a brake fluid pressure higher than an output fluid pressure of a master cylinder to act on a wheel brake.
[0002]
[Prior art]
Conventionally, such a brake fluid pressure control device for a vehicle is already known, for example, in Japanese Patent Laid-Open No. 10-152041.
[0003]
[Problems to be solved by the invention]
In the apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-152041, the output of the master cylinder is pressurized by a pump to act on the wheel brake, and the pump and the wheel brake are communicated even when the pump is pressurized. Pressure increase state that shuts off between the wheel brake and reservoir, hydraulic pressure holding state that shuts off between the pump and wheel brake and between the wheel brake and reservoir, and between pump and wheel brake and between wheel brake and reservoir The brake fluid pressure of the wheel brake is controlled by selectively switching between the reduced pressure state communicating with the wheel brake.
[0004]
However, in a state where the output hydraulic pressure of the master cylinder is increased by the pump, the hydraulic pressure of the reservoir does not become lower than the output hydraulic pressure of the master cylinder. For this reason, it becomes difficult to discharge the brake fluid from the wheel brake to the reservoir, and it may be difficult to reduce the brake fluid pressure of the wheel brake.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicular brake hydraulic pressure control device capable of avoiding a situation in which the brake hydraulic pressure of a wheel brake cannot be reduced. And
[0006]
[Means for Solving the Problems]
To achieve the above object, the present onset Ming, capable of outputting a master cylinder fluid pressure to the first hydraulic pressure passage; the output hydraulic pressure of the master cylinder and the pressurizing pump capable; check to the suction side of the pump A reservoir connected via a valve; a second hydraulic pressure path connected to the discharge side of the pump; a first switching state in which the second hydraulic pressure path directly communicates with the first output hydraulic pressure path and the first liquid Switching valve means for selectively switching a second switching state for communicating a pressure path between the check valve and the suction side of the pump; and communicating between the second hydraulic pressure path and the wheel brake and the wheel brake and The pressure increasing state for blocking between the reservoirs, the hydraulic pressure holding state for blocking both the second hydraulic pressure path and the wheel brake and between the wheel brake and the reservoir, and the second hydraulic pressure path and the wheel brake are blocked. Wheel blur Wood and alternatively the switchable control valve means and a reduced pressure state for communicating between reservoir; equipped with, the hydraulic system between the second hydraulic pressure passage and the master cylinder flexures in response to fluid pressure acting in the vehicle brake hydraulic pressure control device that is sealing member does not exist to flex in response to fluid pressure acting on the hydraulic system between the non-sealing member present that of the second liquid pressure passage and said pump, said first liquid A detector for detecting the hydraulic pressure in the pressure path; when the detected hydraulic pressure of the detector exceeds a required brake hydraulic pressure estimated from a deceleration state of the vehicle when the switching valve means is in the second switching state; wherein the control unit switches the switching valve means to the first switching state the second switching state; see contains the said control unit, the time of the pressure increasing state when the switching valve means is in the second switching state the first In the above-mentioned pressure-increasing state when in the switching state A duty ratio that is longer than, characterized by duty control of said control valve means.
[0007]
According to such a configuration, when the master cylinder outputs a hydraulic pressure that is higher than the necessary brake pressure estimated from the deceleration state of the vehicle, the switching valve means is set to the first switching state and pressurization by the pump is stopped. , it is possible gel pumped brake fluid in the reservoir by a pump, while ensuring the necessary brake fluid pressure, it is possible to avoid the state in which the reduced pressure of the brake fluid pressure becomes impossible occurs, also pressurized by the pump It is possible to prevent a state in which the pressure cannot be increased during the brake fluid pressure control in the pressure state. In other words, when the pressurization by the pump is stopped and the master cylinder and the second hydraulic pressure path are in communication, the second hydraulic pressure path and the master in a state where the second hydraulic pressure path and the wheel brake are disconnected. In the hydraulic system between the cylinders, there is a seal member or the like that bends according to the action of the hydraulic pressure. Therefore, the seal member or the like is changed according to the switching from the disconnection between the second hydraulic pressure path and the wheel brake to the communication. The brake fluid pressure of the wheel brake can be sufficiently increased by causing the brake fluid to be bent to flow toward the wheel brake. On the other hand, when the pressure between the master cylinder and the second hydraulic pressure passage is shut off and the pressurization is performed by the pump, the second hydraulic pressure passage in a state where the second hydraulic pressure passage and the wheel brake are shut off. In the hydraulic system between the pump and the pump, there is no seal member or the like that bends according to the action of the hydraulic pressure, and the hydraulic pressure is confined in the rigid space. For this reason, a sufficient amount of brake fluid cannot be quickly supplied to the wheel brake side in response to switching from the disconnection between the second hydraulic pressure passage and the wheel brake to the communication, and the brake fluid pressure of the wheel brake is sufficiently increased. Can not do it. Therefore, the time of the pressure increasing state when the switching valve means is in the second switching state (at the time of pressurization by the pump) is greater than the time of pressure increasing state at the time of the first switching state (when the pressurization is stopped by the pump). By performing duty control of the control valve means with a longer duty ratio, it is possible to quickly increase the brake fluid pressure of the wheel brakes even during pressurization by the pump.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0010]
FIG. 1 and FIG. 2 show an embodiment of the present invention, FIG. 1 is a circuit diagram showing the overall configuration of a brake fluid pressure control device, and FIG. 2 is a flowchart showing a control procedure by a control unit.
[0011]
First, in FIG. 1, for example, a brake operating force is input from a brake pedal 4 to a master cylinder 1 mounted on a four-wheel vehicle via a negative pressure booster 2. The master cylinder 1 is configured in a tandem type, and includes, for example, a first output port 5 corresponding to a left front wheel brake BF and a right rear wheel brake BR, and a right front wheel brake (not shown). 1) and a second output port 6 corresponding to a left rear wheel brake (not shown), and the first and second output ports 5 and 6 have first hydraulic pressure passages 7 and 8 respectively. Connected.
[0012]
The brake fluid pressure control device on the first output port 5 side and the brake fluid pressure control device on the second output port 6 side have the same configuration, and hereinafter the brake fluid on the first output port 5 side. Only the portion related to the pressure control device will be described, and the description of the portion related to the brake hydraulic pressure control device on the second output port 6 side will be omitted.
[0013]
The output hydraulic pressure of the master cylinder 1 can be pressurized by a pump 10 that includes a suction valve 11 and a discharge valve 12 and is driven by a motor 9. The discharge side of the pump 10, that is, the discharge valve 12 is a second hydraulic pressure path. 13 is connected.
[0014]
The suction side of the pump 10, that is, the suction valve 11 is connected to the reservoir 19 via the check valve 22, and when the output hydraulic pressure of the master cylinder 1 is increased by the pump 10, the suction valve 11 and the check valve 22 are connected. The first hydraulic path 7 is communicated.
[0015]
A control valve means 14 is provided between the second hydraulic pressure passage 13 and the both wheel brakes BF and BR. The control valve means 14 is provided between the left front wheel wheel brake BF and the second hydraulic pressure passage 13. The normally open solenoid valve 15, the right rear wheel wheel brake BR and the normally open solenoid valve 16 provided between the second hydraulic pressure passages 13, and the wheel brakes BF, BR side to the second hydraulic pressure passage 13 side. Is normally provided between the pair of one-way valves 17 and 18 connected in parallel to the normally open solenoid valves 15 and 16 respectively, and the wheel brakes BF and BR and the reservoir 19. Closed solenoid valves 20 and 21 are provided.
[0016]
Such a control valve means 14 opens the normally open solenoid valves 15 and 16 and closes the normally closed solenoid valves 20 and 21 so that the second hydraulic path 13 and the wheel brakes BF and BR are turned on. The pressure-increasing state that allows communication between the wheel brakes BF and BR and the reservoir 19 and the normally open solenoid valves 15 and 16 are closed and the normally closed solenoid valves 20 and 21 are closed. A hydraulic pressure holding state in which the hydraulic path 13 and the wheel brakes BF and BR and between the wheel brakes BF and BR and the reservoir 19 are both shut off, the normally open solenoid valves 15 and 16 are closed, and the normally closed solenoid is closed. By opening the valves 20 and 21, the second hydraulic pressure path 13 and the wheel brakes BF and BR are shut off, and the reduced pressure state in which the wheel brakes BF and BR and the reservoir 19 are communicated is selected. The hydraulic pressure of the second hydraulic pressure passage 13 is controlled by controlling the opening and closing of the normally open solenoid valves 15 and 16 and the normally closed solenoid valves 20 and 21 to control the wheel brakes BF, It can act on BR.
[0017]
The first hydraulic pressure path 7 is connected via the normally closed solenoid valve 23 to the suction side of the pump 10, that is, between the suction valve 11 and the check valve 22, and is switched in cooperation with the normally closed solenoid valve 23. The valve means 25 is connected to the second hydraulic pressure passage 13 through a normally open solenoid valve 24.
[0018]
Thus, the switching valve means 25 closes the normally closed solenoid valve 23 and opens the normally open solenoid valve 24, and opens the normally closed solenoid valve 23 and closes the normally open solenoid valve 24. The first hydraulic pressure path 7 connected to the master cylinder 1 is directly communicated with the second hydraulic pressure path 13 and the pump is operated to selectively switch between the second switched state and the first switched state. In the second switching state, the first hydraulic pressure passage 7 is communicated with the suction side of the pump 10 and the direct communication state with the second hydraulic pressure passage 13 is released.
[0019]
The normally open electromagnetic valve 24 in the switching valve means 25 is connected in parallel with a one-way valve 26 that allows the brake fluid to flow from the first hydraulic pressure path 7 to the second hydraulic pressure path 13 side, A relief valve 27 that opens when the hydraulic pressure of the second hydraulic pressure passage 13 is higher than the relief pressure and releases the hydraulic pressure from the second hydraulic pressure passage 13 to the first hydraulic pressure passage 7 side is connected in parallel. The relief pressure of the relief valve 27 can be adjusted.
[0020]
The on / off operation of the motor 9 for driving the pump 10, the opening / closing duty ratios of the normally open solenoid valves 15 and 16 and the normally closed solenoid valves 20 and 21 in the control valve means 14, and the normality in the switching valve means 25. The opening / closing operation of the closed solenoid valve 23 and the normally open solenoid valve 24 and the relief pressure of the relief valve 27 are controlled by the control unit 28, and the control unit 28 includes the first hydraulic pressure path 7. The detected hydraulic pressure P of the detector 29 that detects the hydraulic pressure is input.
[0021]
The control unit 28 performs control according to the procedure shown in FIG. 2 according to the detected hydraulic pressure P of the detector 29 when the pressurization control by the pump 10 is executed with the switching valve means 25 in the second switching state. In step S1, the necessary brake fluid pressure PN is estimated based on the deceleration state of the vehicle. That is, since the vehicle control unit 28 capable of executing the anti-lock brake control has a function of estimating the estimated vehicle body speed, the required brake fluid pressure PN is calculated from the estimated deceleration.
[0022]
In step S2, the detected hydraulic pressure P by the detector 29 is read, and in the next step S3, the estimated required brake hydraulic pressure PN and the detected hydraulic pressure P by the detector 29 are compared. Thus, when P <PN, that is, when the detected hydraulic pressure P of the detector 29 has not reached the necessary brake hydraulic pressure PN estimated from the deceleration state of the vehicle, the routine proceeds to step S4, and the switching valve means 25 is set. The pressurization control by the pump 10 is continued in the second switching state.
[0023]
On the other hand, when it is determined in step S3 that P ≧ PN, that is, when the detected hydraulic pressure P of the detector 29 is equal to or higher than the required brake hydraulic pressure PN estimated from the deceleration state of the vehicle, the process proceeds to step S5. The switching valve means 25 is changed from the second switching state to the first switching state, and pressurization control by the pump 10 is stopped.
[0024]
Further, the control unit 28 sets the time during which the control valve means 14 is in the pressure-increasing state when the switching valve means 25 is in the second switching state (at the time of pressurization by the pump 10). At certain times (when the pressurization is stopped by the pump 10), the normally open solenoid valves 15 and 16 and the normally closed solenoid valves in the control valve means 14 have a duty ratio that is longer than the time during which the control valve means 14 is in a pressure-increasing state. 20 and 21 are duty controlled.
[0025]
Next, the operation of this embodiment will be described. The control unit 28 determines that the detected hydraulic pressure P of the detector 29 is estimated from the deceleration state of the vehicle when the switching valve means 25 is in the second switching state. Since the switching valve means 25 is switched from the second switching state to the first switching state when the pressure becomes equal to or greater than PN, it is possible to avoid a situation in which the brake fluid pressure cannot be reduced. That is, when the master cylinder 1 outputs a hydraulic pressure higher than the required brake hydraulic pressure PN estimated from the deceleration state of the vehicle, the pressurization by the pump 10 is stopped by setting the switching valve means 25 to the first switching state, The brake fluid in the reservoir 19 can be pumped up by the pump 10, and it is possible to avoid a situation where the brake fluid pressure cannot be reduced while securing the necessary brake fluid pressure PN in the master cylinder 1.
[0026]
Moreover, the control unit 28 controls the control valve means 14 with a duty ratio that is longer than the time of the pressure increasing state when the switching valve means 25 is in the second switching state than the time of the pressure increasing state when the switching valve means 25 is in the first switching state. Since the duty control is performed, it is possible to prevent a state in which the pressure cannot be increased when the brake fluid pressure is controlled by the pump 10 in a pressurized state.
[0027]
In other words, when the pressurization by the pump 10 is stopped and the master cylinder 1 and the second hydraulic pressure path 13 are in communication, the second hydraulic pressure path 13 and the wheel brakes BF and BR are disconnected in the state where they are disconnected. In the hydraulic system between the two hydraulic paths 13 and the master cylinder 1, there are seal members and the like built in the master cylinder 1, and these seal members bend according to the action of the hydraulic pressure. When the control valve means 14 is switched from the reduced pressure or hydraulic pressure holding state to the increased pressure state, the brake fluid that has bent the sealing member or the like can be caused to flow to the wheel brakes BF and BR. The brake fluid pressure of BF and BR can be increased sufficiently.
[0028]
On the other hand, when the pressure between the master cylinder 1 and the second hydraulic pressure path 13 is shut off and the pressurization by the pump 10 is executed, the second hydraulic pressure path 13 and the wheel brakes BF, BR are shut off. In the hydraulic system between the second hydraulic pressure path 13 and the pump 10, there is no seal member or the like that bends according to the action of the hydraulic pressure, and the hydraulic pressure is confined in the rigid space. Therefore sometimes the control valve unit 14 is switched to the pressure increasing state from vacuum or hydraulic pressure holding state, a sufficient amount of brake fluid quickly wheel brakes BF, can not flow to the BR side, the wheel brakes BF, the BR The brake fluid pressure cannot be increased sufficiently.
[0029]
However, the time of the pressure increasing state when the switching valve means 25 is in the second switching state (at the time of pressurization by the pump) is longer than the time of the pressure increasing state at the time of the first switching state (when the pressurization is stopped by the pump). Since the control unit 28 executes the duty control of the control valve means 14 with the increased duty ratio, the brake fluid pressures of the wheel brakes BF and BR can be quickly increased even when the pump 10 is pressurized.
[0030]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0031]
【The invention's effect】
According to the present invention as described above, while ensuring the necessary brake fluid pressure, it is possible to avoid the state in which reduced pressure of the brake fluid pressure becomes impossible occurs also upon pressurization by the pump wheel brake brakes The hydraulic pressure can be quickly increased.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an overall configuration of a brake fluid pressure control device.
FIG. 2 is a flowchart showing a control procedure by a control unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Master cylinder 7 ... 1st hydraulic pressure path 10 ... Pump 13 ... 2nd hydraulic pressure path 14 ... Control valve means 19 ... Reservoir 22 ... Check valve 25 ... .Switching valve means 28 ... control unit 29 ... detectors BF, BR ... wheel brake

Claims (1)

A master cylinder (1) capable of outputting hydraulic pressure to the first hydraulic pressure path (7); a pump (10) capable of pressurizing output hydraulic pressure of the master cylinder (1); and an intake side of the pump (10) A reservoir (19) connected via a check valve (22); a second hydraulic pressure path (13) connected to the discharge side of the pump (10); and a second hydraulic pressure path (13) A first switching state in which the first hydraulic pressure passage (7) is in direct communication and a second switching state in which the first hydraulic pressure passage (7) is communicated between the check valve (22) and the suction side of the pump (10). Switch valve means (25) that can be alternatively switched; and communicates between the second hydraulic pressure path (13) and the wheel brake (BF, BR) and between the wheel brake (BF, BR) and the reservoir (19). Pressure increase state that shuts off the second hydraulic pressure path (13) and the wheel brake (BF, R) and between the wheel brakes (BF, BR) and the reservoir (19), the hydraulic pressure holding state, and between the second hydraulic pressure path (13) and the wheel brakes (BF, BR), and Control valve means (14) capable of selectively switching between a wheel brake (BF, BR) and a reduced pressure state communicating between the reservoir (19) , a second hydraulic pressure path (13) and the master cylinder The hydraulic system between (1) has a sealing member that bends according to the action of the hydraulic pressure, but the hydraulic system between the second hydraulic path (13) and the pump (10) has an action of the hydraulic pressure. In the vehicular brake hydraulic pressure control device in which there is no seal member that bends in response to the detector, the detector (29) for detecting the hydraulic pressure in the first hydraulic pressure path (7); and the switching valve means (25) The detector (29 Detection fluid pressure control unit for switching the first switching state the switching valve means (25) from the second switching state when a the required brake fluid pressure or less, which is estimated from the deceleration state of the vehicle (28); the free Thus, the control unit (28) makes the time of the pressure increasing state when the switching valve means (25) is in the second switching state longer than the time of the pressure increasing state when the switching valve means (25) is in the first switching state. A brake fluid pressure control device for a vehicle , wherein the control valve means (14) is duty-controlled with a duty ratio .

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