JP2005199744A - Brake hydraulic pressure control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake hydraulic pressure control circuit favorable for control and cost reduction by reducing the number of solenoid valves in a semibrake-by-wire type braking device. <P>SOLUTION: Left/right front wheels 4FL, 4FR are braked by master cylinder hydraulic pressure Pm under control of booster valves 17FL, 17FR and pressure reducing valves 18FL, 18FR. Left/right rear wheels 8RL, 8RR are braked by brake hydraulic pressures Prl, Prr obtained by controlling a pump pressure Ppr from a pressure source 10 with booster valves 17RL, 17RR and pressure reducing valves 18RL, 18RR. When brake hydraulic pressures Pfl, Pfr of the left/right front wheels 4FL, 4FR are required to be higher than the master cylinder hydraulic pressure Pm, master cut valves 20L, 20R are closed, a discharge pressure from an exclusive pump 21 to a circuit 22 is used in place of the master cylinder hydraulic pressure Pm, and the discharge pressure is controlled by booster valves 17FL, 17FR and pressure reducing valves 18FL, 18FR to be the required brake hydraulic pressures Pfl, Pfr. This is made possible by opening one valve 31 between inlet circuits 13, 23 of pumps 11, 21. The number of valves for that can be made 1 regardless of the number of front wheel brake systems 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a brake fluid pressure control circuit, and more particularly to a brake fluid pressure control circuit that enables electronic control of the brake fluid pressure.

  When a hydraulic brake or an electric friction brake device that generates a braking force according to the braking operation force of the driver is combined with a regenerative brake device to form a composite brake, for example, the regenerative brake device is a motor / generator. The maximum allowable regenerative braking torque depends on the speed of the vehicle (vehicle speed) and the state of charge of the battery, and there is a demand for using the maximum allowable regenerative braking torque as much as possible from the viewpoint of energy recovery efficiency. It is necessary to electronically control the friction braking force according to the braking operation force.

  In the electronic control of the friction braking force, the required braking torque that can be obtained from the braking operation force of the driver is generated by the friction braking device and the regenerative braking device, and the allowable maximum regenerative braking torque of the regenerative braking device is used as energy. Since there is a requirement to use up the maximum allowable regenerative braking torque from the viewpoint of recovery efficiency, the target maximum braking torque to be generated by the friction braking device is determined by subtracting the maximum allowable regenerative braking torque from the required braking force. The friction braking device is electronically controlled so that the braking torque of the corresponding friction braking device becomes the target friction braking torque.

As a vehicle braking device that can perform such electronic control, there is conventionally known a braking device described in Patent Document 1, for example.
In other words, a shut-off valve that is closed during electronic control is inserted in the brake hydraulic pressure circuit that supplies hydraulic pressure from the master cylinder that responds to depression of the brake pedal to the wheel cylinder of the wheel, and the master cylinder operates in the reservoir. A hydraulic pressure source is provided that includes a pump that discharges liquid as a medium, an electric motor that drives the pump, and an accumulator that accumulates hydraulic fluid from the pump.
In the above electronic control, by using the accumulator internal pressure of the hydraulic pressure source, the brake hydraulic pressure in the wheel cylinder is increased through the pressure increasing valve, or the brake hydraulic pressure in the wheel cylinder is decreased through the pressure reducing valve, The brake fluid pressure can be electronically controlled regardless of the master cylinder fluid pressure.
JP 2000-168536 A

However, in the vehicle braking device that can be electronically controlled as described above, in order to avoid the uncomfortable feeling caused by the change in the brake pedal stroke and reaction force accompanying the electronic control, Since the valve is indispensable, and the brake pedal operation feeling (stroke and reaction force) is required as usual even during electronic control, there is a stroke in the brake hydraulic circuit between this shut-off valve and the master cylinder. It is necessary to connect a simulator.
These shut-off valves and stroke simulators incur a cost penalty due to an increase in the number of parts. In particular, the stroke simulator requires a large amount of man-hours and complicated configuration for tuning that generates a brake pedal feeling as usual, which increases costs. It becomes a big factor.

Therefore, the applicant of the present application uses a first brake system that mechanically brakes one of the front wheels or the rear wheels with a hydraulic pressure from the master cylinder corresponding to the driver's braking operation force (brake pedal depression force), and another energy source. Is developing and proposing a semi-brake by-wire brake device comprising a second brake system that brakes the other rear wheel or front wheel by braking energy obtained by electronically controlling the energy of the vehicle.
According to this semi-brake by-wire type brake device, since the first brake system is a mechanical type, a normal brake pedal feeling can be generated. Therefore, like a conventional full-brake by-wire type brake device, Therefore, the brake device can be electronically controlled at low cost without the need for a stroke simulator.

By the way, in the vehicle brake fluid pressure control device, for example, for dynamic behavior control (VDC) of the vehicle, the machine is not braked (during the master cylinder fluid pressure = 0) while the brake pedal is not depressed. It becomes necessary to give a braking force difference between the left and right wheels related to the first brake system of the equation.
That is, it is necessary to control the brake fluid pressure of the left and right wheels related to the first brake system to a value higher than the master cylinder fluid pressure.
In this case, the first brake system cannot use the master cylinder hydraulic pressure as the original pressure, and uses the hydraulic pressure from another hydraulic pressure source instead of the master cylinder hydraulic pressure.

  As another hydraulic pressure source that replaces the master cylinder hydraulic pressure, there is a hydraulic pressure source for the second brake system, as in the semi-brake-by-wire brake device proposed by the applicant of the present application. For this reason, it is conceivable that this is utilized and no dedicated fluid pressure source is provided as an alternative to the master cylinder fluid pressure.

However, in this configuration, there is a demand to make the left and right wheel brake hydraulic pressure related to the first brake system higher than the master cylinder hydraulic pressure, and the hydraulic pressure from the hydraulic pressure source of the second brake system is supplied to the first brake system. If there is no such request, a plurality of switching valves are required for switching so that the hydraulic pressure from the hydraulic pressure source of the second brake system is not supplied to the first brake system. In the case of the two systems, a switching valve is required for each system, and the number of switching valves increases more and more.
In such a configuration where a plurality of switching valves are required, coupled with the fact that the switching valves are expensive solenoid valves, and the control of these solenoid switching valves becomes troublesome, there is a great cost increase. With the disadvantages.

In the present invention, if another hydraulic pressure source instead of the master cylinder hydraulic pressure is a dedicated hydraulic pressure source different from the hydraulic pressure source of the second brake system,
Even if the first brake system is composed of a plurality of systems, and the switching valve is provided on either the inlet side or the outlet side of the dedicated hydraulic pressure source,
As described above, it is possible to execute control for supplying or not supplying the hydraulic pressure from the dedicated hydraulic pressure source to the first brake system with one switching valve without depending on a plurality of switching valves. From the point of view
An object of the present invention is to propose a brake hydraulic pressure control circuit that embodies this idea and eliminates the above-mentioned cost problem.

For this purpose, the brake fluid pressure control device according to the invention is as described in claim 1,
A first brake system that mechanically brakes a wheel in response to a master cylinder hydraulic pressure output from a master cylinder to which a driver's braking operation force is input;
And a second brake system that brakes another wheel in response to a hydraulic pressure from another pressure source.
The first brake system is provided with a first pressure increasing / reducing valve that makes it possible to control the first brake fluid pressure of the wheels related to the brake system,
The second brake system is provided with a second pressure increasing / decreasing valve that can control the second brake hydraulic pressure of the wheels related to the brake system in accordance with at least the detection result of the braking state by the first brake system.

Further, when a circuit portion between the master cylinder of the first brake system and the first pressure increasing / decreasing valve is required to control the first brake hydraulic pressure of the wheel related to the first brake system to a hydraulic pressure higher than the master cylinder hydraulic pressure. Insert the master cut valve to close,
A further pressure source for supplying hydraulic pressure instead of the master cylinder hydraulic pressure to the portion of the first brake system closer to the wheel than the master cut valve is provided,
When there is the request, the hydraulic pressure from the further pressure source is supplied to the first brake system, and when there is no request, the hydraulic pressure from the further pressure source is supplied to the first brake system. A hydraulic pressure supply valve for preventing the supply is inserted in the circuit of the further pressure source.

The first brake system mechanically brakes the wheel in response to the master cylinder hydraulic pressure, and the first brake hydraulic pressure of the wheel related to this brake system can be controlled by the first pressure increasing / decreasing valve.
The second brake system brakes another wheel in response to the hydraulic pressure from another pressure source. The second brake hydraulic pressure of the wheel related to this brake system is detected at least by the first brake system. It can be controlled by the second pressure increasing / reducing valve according to the result.

When a request to control the first brake fluid pressure higher than the master cylinder fluid pressure occurs, the master cut valve between the master cylinder of the first brake system and the first pressure increase / reduction valve is closed, and the fluid pressure supply valve is further The valve state is switched so that the hydraulic pressure from another pressure source is supplied to the portion of the first brake system closer to the wheel than the master cut valve.
As a result, the first brake fluid pressure can be controlled to a value higher than the master cylinder fluid pressure by the pressure increasing / reducing valve of the first brake system with the fluid pressure from the further pressure source as the original pressure.

When there is no requirement to control the first brake hydraulic pressure higher than the master cylinder hydraulic pressure, and the master cylinder hydraulic pressure can be used as the original pressure, the master cut valve between the master cylinder of the first brake system and the first pressure increasing / reducing valve is opened. At the same time, the hydraulic pressure supply valve is switched to a valve state in which hydraulic pressure from the further pressure source is not supplied to the first brake system.
As a result, the hydraulic pressure from the further pressure source is not supplied to the first brake system, so that the first brake hydraulic pressure can be controlled using the master cylinder hydraulic pressure as the original pressure.

As described above, according to the present invention, a further pressure source in place of the master cylinder hydraulic pressure is a dedicated pressure source different from the pressure source of the second brake system.
Control to supply or not supply the hydraulic pressure from another pressure source in place of the master cylinder hydraulic pressure to the wheels related to the first brake system,
Even if the first brake system is composed of a plurality of systems, even if the hydraulic pressure supply valve is provided on either the inlet side or the outlet side of another pressure source instead of the master cylinder hydraulic pressure,
This can be executed by only one hydraulic pressure supply valve, and coupled with simplification of the control, the above-mentioned cost disadvantage can be eliminated.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a brake fluid pressure control circuit according to an embodiment of the present invention, where 1 is a brake pedal that is depressed by a driver to apply a braking operation force, and 2 is a brake operation force input from the brake pedal 1. Master cylinder.
The braking operation force from the brake pedal 1 is input to the master cylinder 2 under a booster through a booster 3 that allows a negative pressure type, a positive pressure type, and a hydraulic type.

The master cylinder 2 is a tandem master cylinder, and when the internal piston cup is pushed in by the braking operation force, the master cylinder 2 uses the hydraulic fluid from the reservoir 2a as a medium to generate the braking operation force from the two hydraulic outlets 2L and 2R. The corresponding master cylinder hydraulic pressure Pm shall be output.
Brake pipes 6L and 6R are extended from the two hydraulic outlets 2L and 2R of the master cylinder 2 to the braking units (drum brakes, disc brakes, etc.) 5FL and 5FR of the left and right front wheels 4FL and 4FR. The system forms a first brake system 7 for mechanical left and right front wheels.

The braking units (drum brakes, disc brakes, etc.) 9RL, 9RR for the left and right rear wheels 8RL, 8RR include a pressure source 10 different from the master cylinder 2, and the pressure source 10 is constituted by a pump 11 and a motor 12.
The pump 11 driven by the motor 12 can be any one such as a plunger pump or a gear pump, and the working fluid in the reservoir 2a is sucked from the pump inlet circuit 13 and discharged to the pump outlet circuit 14, The left and right rear wheels 8RL and 8RR are braked by operating the braking units 9RL and 9RR with the pump hydraulic pressure Ppr using the discharged hydraulic fluid as a medium.
For this reason, the pump outlet circuit 14 is connected to the braking units 9RL and 9RR of the left and right rear wheels 8RL and 8RR via the brake pipes 15L and 15R, and is used for the left and right rear wheels electronically controlled as described later by these two independent systems. The second brake system 16 is configured.

Hereinafter, the first brake system 7 for the front wheels and the second brake system 16 for the rear wheels will be described in detail.
First, the first brake system 6 will be described. The left and right front wheel brake pipes 6L and 6R, which constitute the first brake system 6, have first pressure increasing valves 17FL and 17FR and a first pressure control valve 17FL and 17FR that can individually control the brake fluid pressures Pfl and Pfr of the left and right front wheels. Pressure reducing valves 18FL and 18FR are provided.
The booster valves 17FL and 17FR are inserted into the brake pipes 6L and 6R as normally open solenoid valves, and the opening degree of the brake pipes 6L and 6R decreases as the booster valves 17FL and 17FR increase the electromagnetic force and reduce the opening. Shall be.
The pressure reducing valves 18FL and 18FR are normally closed solenoid valves whose opening increases as the electromagnetic force increases, and the front wheel brake hydraulic pressure return circuit is connected to the brake piping between the pressure increasing valves 17FL and 17FR and the braking units 5FL and 5FR. Insert in 19.

Master cut valves 20L and 20R are inserted into the brake pipes 6L and 6R between the pressure increasing valves 17FL and 17FR and the master cylinder 2.
These master cut valves 20L and 20R are normally open solenoid valves, but the left and right front wheel brake fluid pressures are individually controlled during the individual control of the left and right front wheel brake fluid pressures Pfl and Pfr by the pressure increasing valves 17FL and 17FR and the pressure reducing valves 18FL and 18FR. If the control is to make Pfl and Pfr higher than the master cylinder hydraulic pressure Pm (including when Pm = 0 when the brake pedal 1 is not depressed), the master cut valves 20L and 20R are closed by turning on the left and right front wheel brake hydraulic pressure Pfl. , Pfr may be controlled within a range equal to or lower than the master cylinder hydraulic pressure Pm, the master cut valves 20L and 20R may be opened by OFF or closed by ON.

In this embodiment, in particular, the pump outlet circuit 22 of the pump 21 constituting another pressure source is connected to each of the brake pipes 6L and 6R between the master cut valves 20L and 20R and the pressure increasing valves 17FL and 17FR. The pump 21 is driven by the motor 12 of the pressure source 10.
The front wheel brake hydraulic pressure return circuit 19 is connected to the pump inlet circuit 23 of the pump 21 and is also connected to an accumulator 24 that temporarily accumulates the return hydraulic pressure from the front wheel brake hydraulic pressure return circuit 19.

Pressure sensors 25L and 25R are connected to the brake pipes 6L and 6R between the master cut valves 20L and 20R and the master cylinder 2, and the master cylinder hydraulic pressure Pm is detected by these pressure sensors 25L and 25R.
In addition, pressure sensors 26FL and 26FR are connected to the brake piping 6L and 6R between the booster valves 17FL and 17FR and the braking units 5FL and 5FR, and these pressure sensors 26FL and 26FR provide the right and left front wheel brake hydraulic pressure Pfl. Detect Pfr.

Next, the second brake system 16 for the rear wheels will be described in detail. The left and right rear wheel brake pipes 15L and 15R constituting the second brake system 16 are supplied with the brake hydraulic pressures Prl and Prr for the left and right rear wheels at least as the first brake system. Second pressure increasing valves 17RL and 17RR and second pressure reducing valves 17RL and 17RR that are individually controllable according to the detection result of the braking state by the brake (front wheel brake) system 7 are provided as described later.
The booster valves 17RL and 17RR are inserted into the brake pipes 15L and 15R as normally open solenoid valves, and the opening degree of the brake pipes 15L and 15R decreases as the booster valves 17RL and 17RR increase the electromagnetic force and reduce the opening. Shall be.

The pressure reducing valves 18RL and 18RR are normally closed electromagnetic valves whose opening degree is increased as the electromagnetic force increases, and are rear wheel brakes connected to the brake piping between the pressure increasing valves 15RL and 15RR and the braking units 4RL and 4RR. It is inserted into the hydraulic pressure return circuit 27.
The rear wheel brake hydraulic pressure return circuit 19 is connected to the pump inlet circuit 13 of the pump 11 and also connected to an accumulator 28 that temporarily accumulates the return hydraulic pressure from the rear wheel brake hydraulic pressure return circuit 27.

A pressure sensor 29 is connected to the pump outlet circuit 14, and the pump discharge hydraulic pressure Ppr from the pressure source 10 is detected by the pressure sensor 29.
In addition, pressure sensors 26RL and 26RR are connected to the brake pipes 15L and 15R between the pressure increase valves 17RL and 17RR and the braking units 9RL and 9RR, and the left and right rear wheel brake hydraulic pressures are provided by these pressure sensors 26RL and 26RR. Prl and Prr are detected.

Further, in this embodiment, the pump inlet circuit 13 of the pump 11 and the pump inlet circuit 23 of the pump 21 are connected to each other by a passage 30 and the hydraulic pressure supply valve 31 is inserted in this passage.
This valve 31 is a normally closed solenoid valve, and is opened when the front wheel high pressure is required to control the front wheel brake hydraulic pressures Pfl and Pfr to a value higher than the master cylinder hydraulic pressure Pm.

Next, the operation of the brake fluid pressure control circuit according to this embodiment will be described.
When the driver depresses the brake pedal 1 in order to brake the vehicle, the hydraulic pressure Pm from the master cylinder 2 is changed to the braking units 5FL and 5FR via the master cut valves 20L and 20R and the pressure increasing valves 17FL and 17FR. The front wheel brake fluid pressures Pfl and Pfr are reached, and the left and right front wheels 4FL and 4FR can be braked.
During this time, the pump discharge pressure Ppr from the pressure source 10 is supplied to the braking units 9RL and 9RR of the left and right rear wheels 8RL and 8RR as the left and right rear wheel brake hydraulic pressures Prl and Prr by the pipes 15L and 15R and the open pressure increasing valves 17RL and 17RR. The left and right rear wheels 8RL and 8RR can be braked.

  When controlling the left and right rear wheel brake fluid pressures Prl and Prr, the opening of the pressure increasing valves 17RL and 17RR and the pressure reducing valves 18RL and 18RR is controlled, and the left and right rear wheel brake fluids are determined by the correlation of the opening of the pressure increasing and reducing valves that form a pair. Electronically, the detected values of the pressures Prl, Prr are electronically set to target values determined according to at least the detection result of the front wheel braking state by the first (front wheel) brake system 7 (for example, master cylinder hydraulic pressure Pm or brake pedal operation amount). By controlling, it can contribute to front and rear wheel braking force distribution control (EBD), anti-skid control (ABS), traction control (TCS), and dynamic vehicle behavior control (VDC).

  In controlling the left and right front wheel brake hydraulic pressures Pfl and Pfr, the opening of the pressure increasing valves 17FL and 17FR and the pressure reducing valves 18FL and 18FR are controlled, and the left and right front wheel brake hydraulic pressures Pfl, By controlling the detected value of Pfr to be the target value, front and rear wheel braking force distribution control (EBD), anti-skid control (ABS), trunkion control (TCS), dynamic vehicle behavior control (VDC) ).

By the way, in the latter left and right front wheel brake fluid pressure (Pfl, Pfr) control, this control is to make the front wheel brake fluid pressure (Pfl, Pfr) higher than the master cylinder fluid pressure Pm (for example, performed during non-braking) In the case of VDC, TCS), the master cut valves 20L and 20R are shut off by turning ON, and the hydraulic pressure supply valve 31 is opened by turning ON and the inlet circuit 23 of the pump 21 is connected to the pump inlet circuit 13 to the reservoir 2a. As a result, the suction circuit of the pump 21 is formed.
As a result, the pump 21 sucks the brake fluid in the reservoir 2a through the pump inlet circuit 13, the valve 31, and the pump inlet circuit 23, generates a discharge pressure, and supplies it to the front wheel brake pipes 6L and 6R from the pump output circuit 22. Can do.

On the other hand, since the master cut valves 20L and 20R are closed as described above, the pump discharge pressure from the pump 21 through the pump outlet circuit 22 to the front wheel brake pipes 6L and 6R leaks to the low-pressure master cylinder 2 side. Without going to the left and right front wheel braking units 5FL and 5FR, the opening control of the pressure increasing valves 17FL and 17FR and the pressure reducing valves 18FL and 18FR allows the left and right front wheel brake hydraulic pressures Pfl, Pfr can be controlled to a value higher than the master cylinder hydraulic pressure Pm.
Since the master cut valves 20L and 20R are shut off during this time, there is a problem that the stroke of the brake pedal 1 changes during the control of the front wheel brake fluid pressure (Pfl, Pfr) (the pedal kickback occurs). It can be avoided.

If anti-skid control is required to adjust the left and right front wheel brake fluid pressure (Pfl, Pfr) to a pressure within the range of the master cylinder fluid pressure Pm or less, the master cut valves 20L and 20R are opened by turning OFF, The hydraulic pressure supply valve 31 is closed by turning OFF, shutting off the inlet circuit 23 of the pump 21 from the pump inlet circuit 13, and hence the reservoir 2a, so that the inlet circuit 23 of the pump 21 is connected only to the front wheel brake hydraulic pressure return circuit 19. .
In this state, the pump 21 cannot output the hydraulic pressure to the outlet circuit 22, and the master cylinder hydraulic pressure Pm is used as the original pressure, and the pressure control valves 17FL and 17FR and the pressure reducing valves 18FL and 18FR are controlled by the opening degree to make a pair. The left and right front wheel brake fluid pressures Pfl and Pfr can be controlled as prescribed by the correlation between the opening and closing of the pressure increasing / reducing valve.

By the way, according to the present embodiment, the pump 21 which is still another pressure source in place of the master cylinder hydraulic pressure Pm is used as a dedicated pressure source different from the pressure source 10 of the second brake system 16.
Master the left and right front wheel brake fluid pressure (Pfl, Pfr) for vehicle dynamic behavior control (VDC) and trunking control (TCS), which are often performed during non-braking (when master cylinder Pm = 0) There is a demand to make the pressure higher than the cylinder hydraulic pressure Pm, and the hydraulic pressure from the pump 21 (another pressure source in place of the master cylinder hydraulic pressure Pm) to the circuit 22 is supplied to the left and right front wheels related to the first brake system 7. The control that the above-mentioned request disappears and the pump hydraulic pressure to the circuit 22 is not supplied to the first brake system 7,
Even if the first brake system 7 is composed of a plurality of systems 6L and 6R, the hydraulic pressure supply valve 31 is connected to the inlet circuit 23 or outlet of the pump 21 (another pressure source in place of the master cylinder hydraulic pressure Pm). Regardless of which circuit 22 is provided, it can be executed by only one hydraulic pressure supply valve 31, which is very advantageous in terms of cost.

When the hydraulic pressure supply valve 31 that controls the above control is provided in the inlet circuit 23 of the pump 21 as in the present embodiment, the following operational effects can be obtained.
That is, when the hydraulic pressure supply valve 31 is provided in the outlet circuit 22 of the pump 21, there is a problem that high pressure durability is required, a relief valve needs to be installed, or the energy loss of the pump 21 increases. However, when the hydraulic pressure supply valve 31 is provided in the inlet circuit 23 of the pump 21, these problems do not occur.

Moreover, as in this embodiment, when the hydraulic pressure supply valve 31 is inserted into the passage 30 provided between the inlet circuit 23 of the pump 21 and the inlet circuit 13 of the pump 11,
As the suction circuit from the reservoir 2a of the pump 21 to be formed when the hydraulic pressure supply valve 31 is opened, the inlet circuit 13 of the pump 11 for the second brake system 16 is used. The simplification of the circuit configuration can be realized by sharing.

In the brake fluid pressure control circuit of FIG. 1, when the electronic control system of the second brake system 16 that is electronically controlled fails, both systems 15L and 15R constituting the second brake system become inoperable, and the master cylinder The braking is performed by the two-wheel braking of the left and right front wheels by the two systems 6L and 6R forming the mechanical first brake system 7 that responds to the hydraulic pressure Pm.
In addition, when one of the two systems 6L and 6R constituting the mechanical first brake system 7 fails, both the systems 6L and 6R communicated by the pump outlet circuit 22 become inoperable and electronically controlled. This is braking by two-wheel braking of the left and right rear wheels by the two systems 15L and 15R of the second brake system 16.

FIG. 2 shows that when one of the two systems 6L and 6R constituting the first brake system 7 fails like the latter, the two-wheel braking can be changed to the three-wheel braking, and the reduction of the braking force of the vehicle can be suppressed. Another example of the brake fluid pressure control device according to the present invention will be described.
In the present embodiment, the fail-safe valve 32 is inserted into a circuit portion that bridges between the left and right front wheel brake pipe lines 6L and 6R in the outlet circuit 22 of the pump 21.
This fail-safe valve 32 is a normally closed solenoid valve that opens when ON and communicates between the left and right front wheel brake pipelines 6L and 6R at locations closer to the left and right front wheel braking units 5FL and 5FR than the master cut valves 20L and 20R. Shall.

The operation of the brake fluid pressure control apparatus of this embodiment, which has the same configuration as the brake fluid pressure control apparatus of FIG. 1 except that the fail-safe valve 32 is provided, is as follows.
Except when the first brake system 7 has failed, the fail-safe valve 32 is opened by ON to keep the left and right front wheel brake pipe lines 6L and 6R in communication.
Accordingly, the brake fluid pressure control circuit of FIG. 2 becomes the same as the brake fluid pressure control device shown in FIG. 1, and functions in the same manner as described above and can provide the same operational effects.

When one of the left and right front wheel brake lines 6L and 6R forming the first brake system 7 fails, it is detected that the difference in the master cylinder hydraulic pressure Pm in the left and right front wheel brake lines 6L and 6R has increased. The failure of one system is judged by the method, and the fail-safe valve 32 is turned OFF and closed.
As a result, the master cylinder hydraulic pressure Pm does not leak from the normal front wheel brake line 6L or 6R to the failed front wheel brake line 6R or 6L, and the master cylinder to the normal front wheel brake line 6L or 6R. The corresponding front wheel can be braked by the hydraulic pressure Pm.

On the other hand, the braking of the left and right rear wheels 8RL and 8RR by the second brake system 16 is not affected by the failure of the first brake system 7 by closing the hydraulic pressure supply valve 31, so that Is possible.
In other words, the left and right rear wheels 8RL and 8RR are normally braked by the left and right rear wheel brake fluid pressures Prl and Prr regulated by the pressure increasing valves 17RL and 17RR and the pressure reducing valves 18RL and 18RR with the pump pressure Ppr from the pump 11 as a source pressure. Can do.
Therefore, when one of the left and right front wheel brake lines 6L and 6R forming the first brake system 7 fails, one front wheel 4FL or 4FR related to the normal front wheel brake line 6L or 6R and the left and right rear wheels 8RL and 8RR Can be braked by three wheels.

  By the way, when both the left and right front wheel brake pipes 6L and 6R forming the first brake system 7 are normal and one of the left and right rear wheel brake hydraulic pressures Prl and Prr cannot be generated, In order to prevent the hydraulic pressure from leaking from the brake line 15L or 15R to the failed rear wheel brake line 15R or 15L, the pressure increasing valve 17RR or 17RL in the failed rear wheel brake line 15R or 15L is closed by turning ON, As a result, the rear wheel 8RL or 8RR related to the normal rear wheel brake line 15L or 15R can be braked.

Further, by closing the hydraulic pressure supply valve 31 so that the failure of the second brake system 16 for the rear wheels does not affect the first brake system 7 for the front wheels, the first brake system 7 is The right and left front wheels 4FL and 4FR can be properly braked by the master cylinder hydraulic pressure Pm applied to the left and right front wheel brake pipe lines 6L and 6R.
Therefore, in the event of a failure in which one of the left and right rear wheel brake hydraulic pressures Prl and Prr can no longer be generated, one rear wheel 8RL or 8RR related to the normal rear wheel brake line 15L or 15R and the left and right front wheels 4FL, Braking by 3 wheels with 4FR is possible.

  As described above, in this embodiment, in addition to the effects described above with reference to FIG. 1, when one of the left and right front wheel brake systems fails or when one of the left and right rear wheel brake systems fails, the three wheels Braking can be ensured, and a reduction in the braking force of the vehicle at the time of failure can be reduced as compared with the two-wheel braking of FIG.

In the embodiment shown in FIGS. 1 and 2, the brake system related to the left and right front wheels 4FL and 4FR is the first mechanical brake system 7 that responds to the master cylinder hydraulic pressure Pm, and the brake system related to the left and right rear wheels 8RL and 8RR. The system is an electronically controlled second brake system 16 that responds at least to the detection result of the braking state by the first brake system 7. However, it is a matter of course that similar effects can be achieved even if these relationships are reversed. Yes,
Alternatively, the brake system related to the left front wheel 4FL and the right rear wheel 8RR is a mechanical first brake system that responds to the master cylinder hydraulic pressure Pm, and the brake system related to the right front wheel 4FR and the left rear wheel 8RL is electronically controlled. A two-brake system may be used.
In addition, each solenoid valve is an ON / OFF type instead of one that adjusts the opening according to the electromagnetic force, and controls the brake fluid pressure by controlling the ON / OFF time. It doesn't matter.

1 is a hydraulic circuit diagram showing a brake hydraulic pressure control circuit according to an embodiment of the present invention. FIG. 5 is a hydraulic circuit diagram showing a brake hydraulic pressure control circuit according to another embodiment of the present invention.

Explanation of symbols

1 Brake pedal 2 Master cylinder 3 Booster
4FL, 4FR Left and right front wheels
5FL, 5FR Left and right front wheel braking unit
6L, 6R Left and right front wheel brake piping 7 First brake system
8RL, 8RR Left and right rear wheels
9RL, 9RR Left and right rear wheel braking unit
10 Different pressure sources
11 Pump
12 Motor
13,23 Pump inlet circuit
14,22 Pump outlet circuit
15L, 15R Left and right rear wheel brake piping
16 Second brake system
17FL, 17FR First booster valve
18FL, 18FR 1st pressure reducing valve
17RL, 17RR Second booster valve
17RL, 17RR Second pressure reducing valve
19 Front wheel brake hydraulic pressure return circuit
20L, 20R Master cut valve
21 Pump
24 Accumulator
25L, 25R, 26FL, 26FR, 26RL, 26RR, 29 Pressure sensor
27 Rear brake fluid pressure return circuit
28 Accumulator
30 passage
31 Hydraulic supply valve
32 Fail-safe valve

Claims (5)

A first brake system that mechanically brakes a wheel in response to a master cylinder hydraulic pressure output from a master cylinder to which a driver's braking operation force is input;
A second brake system that brakes another wheel in response to fluid pressure from another pressure source;
The first brake system is provided with a first pressure increasing / reducing valve that makes it possible to control the first brake fluid pressure of the wheels related to the first brake system,
The second brake system is provided with a second pressure increasing / decreasing valve that makes it possible to control the second brake hydraulic pressure of the wheels related to the second brake system according to at least the detection result of the braking state by the first brake system,
The circuit portion between the master cylinder of the first brake system and the first pressure increasing / reducing valve is closed when there is a request to control the first brake hydraulic pressure of the wheel related to the first brake system to a hydraulic pressure higher than the master cylinder hydraulic pressure. Insert the master cut valve,
A further pressure source for supplying hydraulic pressure instead of the master cylinder hydraulic pressure to the portion of the first brake system closer to the wheel than the master cut valve is provided,
When there is the request, the hydraulic pressure from the further pressure source is supplied to the first brake system, and when there is no request, the hydraulic pressure from the further pressure source is supplied to the first brake system. A brake hydraulic pressure control circuit, wherein a hydraulic pressure supply valve for preventing supply is inserted in the circuit of the further pressure source. In the brake fluid pressure control circuit according to claim 1,
The hydraulic pressure supply valve is inserted into the inlet circuit of the further pressure source, and when requested, the hydraulic pressure supply valve is opened so that the hydraulic pressure from the additional pressure source is transferred to the first brake system. A brake fluid pressure control circuit configured to be supplied. In the brake fluid pressure control circuit according to claim 2,
A passage for connecting the inlet circuit of the further pressure source to the inlet circuit of the another pressure source is provided, and the fluid pressure supply valve is inserted into the passage, and when there is the demand, the fluid pressure supply valve is A brake fluid pressure control circuit, wherein the brake fluid pressure control circuit is configured to open and to supply fluid pressure from the further pressure source to the first brake system. In the brake fluid pressure control circuit according to any one of claims 1 to 3,
The master cylinder is a tandem master cylinder,
The first brake system is made up of two systems from two hydraulic outlets of the tandem master cylinder to two wheels, and an outlet circuit of the further pressure source is connected to each of these two systems. Brake fluid pressure control circuit. In the brake fluid pressure control circuit according to claim 4,
A fail-safe valve that is shut off when one system of the first brake system becomes inoperable is inserted into the outlet circuit portion of the further pressure source that extends between the two systems that form the first brake system. Brake hydraulic pressure control circuit characterized by that.

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