JP3067518B2 - Brake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for arbitrarily controlling brake fluid pressure applied to each wheel.

[0002]

2. Description of the Related Art Conventionally, as a brake control device, for example, a brake control device described in Japanese Patent Application Laid-Open No. 4-8767 is known.

The above-mentioned conventional source discloses an apparatus for controlling a brake pressure supplied to a wheel cylinder at the time of a braking operation by using an electro-hydraulic control valve for adjusting a hydraulic pressure according to a master cylinder pressure.

That is, the above-mentioned electro-hydraulic control valve is provided in the middle of the external hydraulic pressure source and the wheel cylinder, and is provided with a force from a proportional solenoid which pushes the pressure reducing side according to the current value, and a pressure increasing side according to the master cylinder pressure. This is a valve structure having a spool on which a force from a plunger is applied to adjust the external hydraulic pressure supplied from the external hydraulic pressure source to a control pressure corresponding to a difference between two inputs.

Based on this brake control device, the control pressure supply from the electro-hydraulic control valve to the wheel cylinder is cut off when a failure occurs, while the four-wheel independent brake control is achieved in a normal condition, and the master cylinder pressure from the master cylinder is reduced. Is supplied to the wheel cylinder to secure the braking force by the master cylinder pressure when a failure occurs, as shown in FIG. 7, the failure is located downstream of the external hydraulic pressure source by the oil pump 3 and the accumulator 4. A failure valve 7 having an electromagnetic valve structure that cuts off the external hydraulic pressure when an error occurs is provided. In FIG. 7, 1 is a master cylinder, 2 and 12 are wheel cylinders, 5 and 15 are main valves, 6 and 16 are pilot valves, 8 and 18 are switching valves for reducing leakage, and 9 and 19 are pilot switching valves. is there.

[0006]

However, in a brake control system having a fail valve 7 that cuts off the external hydraulic pressure when a failure occurs, when a failure occurs in one of the front and rear systems, a failure occurs. Master cylinders 1 of all systems including those that are not
And the wheel cylinder 2, the total braking force is reduced at the moment when the fail valve 7 is switched based on the occurrence of a failure, which causes a problem that the driver feels strange.

That is, when the system is normal, the control pressure is adjusted to a control pressure higher than the master cylinder pressure by the boosting function of the hydraulic control valve constituted by the pilot valves 6, 16 and the main valves 5, 15. It is in the state of supplying. However, when a failure occurs, the master cylinder pressure is directly supplied to the wheel cylinder 2 by the switching operation of the failure valve 7, and the wheel cylinder pressure of all the four front and rear wheels becomes the master cylinder pressure level, so that the total control is performed. The power decreases, and the range of change in the braking force before and after the switching operation of the fail valve 7 increases.

In order to solve this problem, as shown in FIG. 8, a front-side fail valve 17 and a rear-side fail valve 7 are provided for each of two systems on the front side and the rear side. Even after that, there is a plan to secure hydraulic control on the other non-fail side.

However, in this case, when only the front brake control system fails, the master cylinder pressure is supplied to the front wheel cylinder, whereas the hydraulic control valve is supplied to the rear wheel cylinder. As a result, the boosted control pressure is supplied, and there is a problem that the rear wheels are locked and the operability is reduced.

That is, at the time of braking, the position of the center of gravity of the vehicle moves forward due to the deceleration applied to the vehicle body, and the wheel load on the front wheel side (front side) increases with the movement of the center of gravity, and the rear wheel side (rear side) Presents a situation in which the wheel load of the vehicle decreases.
Therefore, the front side is hardly locked even when the braking force is slightly larger than the rear side, but the rear side is easily locked when a braking force larger than the front side is applied.

The present invention has been made in view of the above problem, and a common object is to provide a brake control system having two independent front and rear wheel systems having independent fail-safe functions. An object of the present invention is to achieve both suppression of a driver's uncomfortable feeling of braking when a failure occurs only in the driver and prevention of rear wheel lock when a failure occurs only in the front brake control system.

[0012]

According to a first aspect of the present invention, there is provided a brake control device for generating a master cylinder pressure corresponding to a brake operating force, as shown in FIG. a, each wheel cylinder b, b ′ provided in the braking device of each wheel and operated by a control pressure higher than the master cylinder pressure, and an external hydraulic pressure source c that generates a hydraulic pressure independently of the brake operation; An external hydraulic pressure source is provided for each of the two systems of the front wheel side (front side) and the rear wheel side (rear side). The master cylinder pressure is used as a signal pressure, and the force generated by the signal pressure and the force generated by the solenoid are input. And a rear hydraulic control valve d 'for regulating the external hydraulic pressure supplied from the controller to a control pressure corresponding to the difference between the two inputs. When only the control system fails, the master cylinder pressure is directly applied to the rear wheel cylinder b ', and the control pressure from the front hydraulic control valve d is applied to the front wheel cylinder b. When only a failure occurs, the control pressure from the rear hydraulic control valve d 'is applied not only to the rear wheel cylinder b' but also to the front wheel cylinder b.
A failure handling control means g is provided.

More specifically, in the brake control device according to the first aspect, a front-side fail valve e for selecting and outputting an external hydraulic pressure or a return pressure according to an external command.
And a front-side pilot switching valve for selecting the supply pressure to the wheel cylinders b and b 'using the output pressures of the rear-side fail valve e' and the front-side fail valve e and the rear-side fail valve e 'as valve operating pressures. f and a rear-side pilot switching valve f ′ are provided. The front-side pilot valve f connects the front-side wheel cylinder b to the rear-side wheel cylinder b ′ when the return pressure is selected, and the front-side pilot valve f ′ when the external hydraulic pressure is selected. Side hydraulic control valve d and wheel cylinder b. The rear pilot valve f ′ is connected to the master cylinder a and the wheel cylinder b ′ when return pressure is selected.
And the rear hydraulic control valve d 'and the wheel cylinder b' are connected when the external hydraulic pressure is selected, and the first fail-corresponding control means g is provided when only the rear brake control system fails. An external hydraulic pressure selection command is output to the side fail valve e and a return pressure selection command is output to the rear side fail valve e '. When only the front brake control system fails, a return pressure selection command is issued to the front side fail valve e. And outputs an external hydraulic pressure selection command to the rear-side fail valve e ′.

In order to achieve the above object, in the brake control device according to the second invention, as shown in the claim correspondence diagram of FIG. 2, a master cylinder a for generating a master cylinder pressure corresponding to a brake operating force, Provided in the braking device,
Each wheel cylinder b, b 'operated by a control pressure higher than the master cylinder pressure, an external hydraulic pressure source c for generating hydraulic pressure regardless of brake operation, a front wheel side (front side) and a rear wheel side (rear side) Side), the master cylinder pressure is used as the signal pressure, the force generated by the signal pressure and the force generated by the solenoid are input, and the external hydraulic pressure supplied from the external hydraulic pressure source is applied to two inputs. A front-side hydraulic control valve d and a rear-side hydraulic control valve d 'that regulate the control pressure according to the difference, when only the rear-side brake control system fails, the rear-side wheel cylinder b' And the control pressure from the front side hydraulic control valve d is applied to the front side wheel cylinder b. When only the front side brake control system fails, the All the wheel cylinder b DOO side and the rear side, the b 'in that a second failure response control means h adding master cylinder pressure, characterized.

More specifically, in the brake control device according to the third aspect, a front-side fail valve e for selecting and outputting an external hydraulic pressure or a return pressure according to an external command.
And a front-side pilot switching valve for selecting the supply pressure to the wheel cylinders b and b 'using the output pressures of the rear-side fail valve e' and the front-side fail valve e and the rear-side fail valve e 'as valve operating pressures. f and a rear-side pilot switching valve f ′ are provided. The front-side pilot valve f and the rear-side pilot valve f ′ connect the master cylinder a and the wheel cylinders b and b ′ when return pressure is selected, and The hydraulic control valves d and d 'are connected to the wheel cylinders b and b' at the time of selection, and the second fail corresponding control means h is connected to the front fail valve e when only the rear brake control system fails. An external fluid pressure selection command is output and a return pressure selection command is output to the rear fail valve e '. When only the front brake control system fails, the front Wherein the both Le valves e and the rear side fail valve e 'is a means for outputting a return pressure selection command.

[0016]

The operation of the first invention will be described.

When the system is normal, the front-side fail valve e and the rear-side fail valve e ′ change the external hydraulic pressure from the external hydraulic pressure source c to the pilot switching valves f and f according to an external command.
f 'is selected and the pilot switching valve f,
f 'is in a state in which the control pressure regulated by the front hydraulic control valve d and the rear hydraulic control valve d' is switched to the side that guides them to the wheel cylinders b and b ', respectively. When a brake operation is performed in this state, a master cylinder pressure corresponding to the brake operation force is generated in the master cylinder a, and this master cylinder pressure is applied to the front-side hydraulic control valve d.
And a signal corresponding to the difference between the force generated by the master cylinder pressure and the force generated by the solenoid in each of the front hydraulic control valve d and the rear hydraulic control valve d '. The braking pressure is adjusted to a pressure, and the control pressure is supplied to each wheel cylinder b, b ′ to apply a braking force to each wheel.

If a failure occurs only in the rear brake control system during this brake operation, the first failure corresponding control means g outputs an external hydraulic pressure selection command to the front failure valve e and outputs a rear failure valve e. 'Is a return pressure selection command. As a result, the master cylinder pressure is applied to the rear wheel cylinder b ', and the control pressure from the front hydraulic control valve d is applied to the front wheel cylinder b.

Therefore, compared to the case where the wheel cylinder pressures of all four wheels are at the master cylinder pressure level when a rear-side failure occurs, the width of change in the total braking force is smaller, and the driver's uncomfortable feeling of braking is suppressed.

On the other hand, when a failure occurs only in the front brake control system during the brake operation, the first failure corresponding control means g outputs a return pressure selection command to the front failure valve e and outputs a rear failure valve e. 'Outputs an external hydraulic pressure selection command. As a result, the control pressure from the rear hydraulic control valve d 'is applied not only to the rear wheel cylinder b' but also to the front wheel cylinder b.

Therefore, the front and rear braking forces are at the same control pressure level, and a sufficient braking force is ensured, and the rear wheel lock, which occurs when the control pressure is applied only to the rear side when the front side fails, is prevented. Is done.

The operation of the second invention will be described.

The brake control action when the system is normal and the fail handling control action when a failure occurs only in the rear brake control system during the brake operation are the same as in the first invention.

In the second invention, when a failure occurs only in the front brake control system during the brake operation,
In the second failure correspondence control means h, a return pressure selection command is output to both the front side failure valve e and the rear side failure valve e ′. As a result, the master cylinder pressure is applied to all of the front and rear wheel cylinders b and b '.

Therefore, the front and rear braking forces are at the same master cylinder pressure level, and the rear wheel lock which would occur when the control pressure is applied only to the rear side during a front side failure is prevented.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the configuration will be described.

FIG. 3 is an overall system diagram showing a brake control device according to a first embodiment corresponding to the first invention.

First, the main structure will be described. In FIG. 3, 1 is a master cylinder, 2, 2, 12, and 12 are wheel cylinders, 3 is an oil pump, 4 is an accumulator (3, 4 is an external hydraulic pressure source c). , 5 and 5 are rear-side main valves, 15 and 15 are front-side main valves, 6 is a rear-side pilot valve, 16 is a front-side pilot valve, 7 is a rear-side fail valve, 17 is a front-side fail valve, 8 is a rear-side leak reduction switching valve, 18 is a front-side leakage reduction switching valve, 9 and 9 are rear-side pilot switching valves, 19 and 19
Denotes a front pilot switching valve.

The master cylinder 1 generates a master cylinder pressure corresponding to a brake operation force applied to a brake pedal.

The wheel cylinders 2, 2, 12, 12
Are provided in the braking device of each wheel, and the main valves 5, 5, 1
It is operated by the control pressure generated by the control cylinders 5, 15 or the master cylinder pressure from the master cylinder 1.

The oil pump 3 is driven by an engine or a motor, and its discharge pressure is accumulated in an accumulator 4.

The main valves 5, 5, 15, and 15 act on the solenoids 5 a, 5 a, 1 in the left direction in the drawing (pressure increasing direction) generated by the pilot pressure from the pilot valves 6, 16.
The force in the right direction of the drawing (pressure reduction direction) generated by 5a and 15a is input, and the external hydraulic pressure supplied from the accumulator 4 is adjusted to a control pressure (four-wheel independent) according to the difference between the two inputs. D is a supply pressure port, E is a control pressure port, and F is a drain port.

The pilot valves 6 and 16 use the master cylinder pressure guided from the master cylinder pressure port G as a signal pressure and adjust the external fluid pressure from the accumulator 4 to a pilot pressure (independent of front and rear wheels) corresponding to the master cylinder pressure. Press.

The main valves 5 and 5 and the pilot valve 6 are provided in the same valve body, and the rear control valve unit V
R (corresponding to the rear-side hydraulic control valve d '), and the main valves 15, 15 and the pilot valve 16 are provided in the same valve body to provide a front-side control valve unit VF (for the front-side hydraulic control valve d). Equivalent).

The rear-side fail valve 7 and the front-side fail valve 17 have a three-position switching solenoid valve structure that can be switched by an external command. The accumulator 4, the rear-side control valve unit VR, and the front-side control valve unit VF are respectively provided. Are connected to a branch point M and an oil path branched from the branch point N in the middle of the oil path. The ON command (external fluid pressure selection command) transmits the external fluid pressure from the accumulator 4 and the OFF command (return pressure). The external hydraulic pressure to the pilot switching valves 9, 9, 19, 19 is drained by the selection command).

The rear-side leakage reduction switching valve 8 and the front-side leakage reduction switching valve 18 use the master cylinder pressure as the valve operating pressure, and when the master cylinder pressure is not generated, the external hydraulic pressure to the supply pressure ports D, D Is shut off, and external hydraulic pressure is supplied to the supply pressure ports D, D when the master cylinder pressure is generated. C is a master cylinder pressure port, A is an input port, and B is an output port.

The rear-side pilot switching valves 9 and 9 are provided downstream of the rear-side fail valve 7. The external hydraulic pressure supplied through the rear-side fail valve 7 is used as a valve operating pressure.
Master cylinder 1 and wheel cylinder 2 at FF command
2 and the control pressure ports E, E of the rear-side control valve unit VR and the wheel cylinders 2, 2 at the time of an ON command. Further, the front-side pilot switching valves 19, 19
An external fluid pressure supplied through the front-side fail valve 17 is provided as a valve operating pressure at a position downstream of the front-side fail valve 17. And the control pressure ports E, E of the front-side control valve unit VF are connected to the wheel cylinders 12, 12 at the time of an ON command. K is an external hydraulic pressure port, I is a control pressure port, H is a master cylinder pressure port, J is a wheel cylinder pressure port, and H 'is a front wheel cylinder pressure port.

The solenoids 5a, 1 of the rear-side fail valve 7 and the front-side fail valve 17 and the main valves 5, 15
5a is driven and controlled by a command from a controller (not shown).

Next, the operation will be described.

[Fail Correspondence Control Operation] FIG. 4 is a flowchart showing the flow of a fail response control operation process performed by the controller. Each step will be described below (corresponding to the first fail correspondence control means g).

In step 30, it is determined whether the front brake control system has failed. In steps 31 and 32, it is determined whether the rear brake control system has failed. These failure determinations are made by monitoring signals and pressure in a failure determination circuit in the controller.

In step 33, when only the rear brake control system fails, the front wheel cylinder pressure control is executed, and an OFF command is output to the rear fail valve 7.

In step 34, when only the front brake control system fails, the rear wheel cylinder pressure control is executed as usual, and the front fail valve 1
7, an OFF command is output.

In step 35, when the brake control system fails on both the rear side and the front side, an OFF command is output to the rear side fail valve 7 and the front side fail valve 17.

[Non-braking with System Normal] During non-braking with system normal, an ON command for selecting the supply of external hydraulic pressure is output from the controller to the rear fail valve 7 and the front fail valve 17. Rear pilot switching valves 9, 9 and front pilot switching valves 19, 1
Reference numeral 9 denotes a position where the port I and the port J communicate with each other using the external hydraulic pressure as a valve operating pressure, that is, the main valves 5, 5, 15, and 15
The position has been switched to the position operated by the control pressure from.

Since the master cylinder pressure from the master cylinder 1 is zero, the leakage reduction switching valves 8, 1
Reference numeral 8 is fixed to the side that blocks the ports A and B shown in FIG.

Therefore, the external hydraulic pressure from the accumulator 4 is shut off at the positions of the leak reduction switching valves 8 and 18 and is not supplied downstream thereof, so that the rear side control valve unit VR and the front side control valve unit Leakage at the spool of the VF is reduced, and waste of the pump discharge flow rate at the oil pump 3 is prevented.

[During braking when the system is normal] When the brake pedal is depressed in the above state, the master cylinder pressure generated in the master cylinder 1 is guided to the port C of the switching valves 8 and 18 for leak reduction. The leakage reduction switching valves 8 and 18 are switched to the side that connects the port A and the port B with the master cylinder pressure as the valve opening operation pressure.

Further, a master cylinder pressure corresponding to the brake operating force is guided to the port G of the rear control valve unit VR and the front control valve unit VF.

Therefore, the external hydraulic pressure from the accumulator 4 is supplied to the supply pressure ports D, D of the rear control valve unit VR and the front control valve unit VF via the leak reduction switching valves 8, 18, and the pilot valve In steps 6 and 16, the supply pressure is adjusted to a pilot pressure corresponding to the magnitude of the master cylinder pressure.
At 5, the control pressure is adjusted to a control pressure corresponding to the difference between the force generated by the pilot pressure and the force generated by the solenoids 5a, 5a, 15a, 15a, and the control pressure is supplied to the wheel cylinders 2, 2, 12, 12. This applies a braking force to each wheel.

The solenoids 5a, 5a, 15a, 15
By making the control commands for a different, the braking force can be controlled independently of the front and rear wheels, the left and right wheels, or the four wheels independently.

[Fail of Rear Brake Control System] If only the rear brake control system fails during the above braking, the flow proceeds from step 30 to step 31 to step 33 in the flowchart of FIG.
Then, the front wheel cylinder pressure control is executed, and an OFF command is output to the rear side fail valve 7.

With this control, the rear-side fail valve 7
The position is switched from the port K of the rear-side pilot switching valves 9 and 9 to the position shown in FIG. 3 where the external hydraulic pressure is drained, and the rear-side pilot switching valves 9 and 9 are switched to the ports H and J by releasing the external hydraulic pressure. Is switched to a position where the wheel cylinders 2 and 2 are operated by the master cylinder pressure from the master cylinder 1, and a braking force is applied to the rear wheel cylinders 2 and 2 by the master cylinder pressure.

On the other hand, the front-side fail valve 17 is kept in the above-mentioned normal state, and the front-side pilot switching valve 1
The positions 9 and 19 are switched to the positions operated by the control pressure from the main valves 15 and 15, and the front side wheel cylinders 12 and 12 are applied with a braking force by the control pressure generated by the main valves 15 and 15.

Therefore, as the total braking force, the wheel cylinder pressures of all four wheels before and after the rear wheel become the master cylinder pressure level only when the rear two wheels decrease from the control pressure level to the master cylinder pressure level. As compared with the case, the change width of the total braking force is small, and when a failure occurs in only one of the systems on the rear side only, the feeling of discomfort to the driver is suppressed to a small level.

[Front-side brake control system failure] If only the front-side brake control system fails during the above-described braking, step 30 in the flowchart of FIG.
The flow proceeds from step 32 to step 34. In step 34, rear wheel cylinder pressure control is executed, and an OFF command is output to the front-side fail valve 17.

By this control, the front side fail valve 1
7 is switched to the position shown in FIG. 3 for draining the external hydraulic pressure from the port K of the front-side pilot switching valves 19, 19, and the front-side pilot switching valves 19, 19
When the external hydraulic pressure is released, the port H 'and the port J communicate with each other, that is, the rear wheel cylinder 2,
2 is switched to a position where the front wheel cylinders 12, 12 are operated by the wheel cylinder pressure from 2,
The control pressure from the rear-side control valve unit VR is applied not only to the rear-side wheel cylinders 2 and 2 but also to the front-side wheel cylinders 12 and 12.

Therefore, the front and rear braking forces are equal and balanced, and a sufficient braking force that does not give a feeling of incompatibility to the driver is ensured. Also, for example, when the control pressure is applied only to the rear side, the rear wheel locks. Is prevented.

[Front / Rear Brake Control System Failure] When the front / rear brake control system fails, step 3 in the flowchart of FIG.
0 → Step 32 → Step 35
In step 35, an OFF command is output to the rear-side fail valve 7 and the front-side fail valve 17.

Therefore, when the brake control system fails in both the front and rear, the braking is performed by the master cylinder pressure as described above, and when the braking force is insufficient, the brake operation force is increased by the modified brake operation. Corresponding.

Next, the effects will be described.

(1) When a failure occurs only in the rear side brake control system, the front side is set to the control pressure and the rear side is set to the master cylinder pressure. When a failure occurs only in the front side brake control system, the front side and the rear side are controlled. The system is designed to perform fail-response control in which both sides are controlled by the control pressure, so that if a failure occurs only in the rear brake control system, the driver will not feel uncomfortable braking, and only the front brake control system will fail. It is possible to achieve compatibility with prevention of rear wheel lock in the event of occurrence.

(2) Since the front and rear braking forces are balanced by setting the control pressure on both the front side and the rear side, when a failure occurs only in the front brake control system, the failure occurs before and after the failure occurs. Thus, the variation width of the total braking force can be substantially eliminated, and a sufficient braking force can be secured as it is, and the driver can be prevented from feeling uncomfortable.

(3) The front-side fail valves are respectively connected to the oil passages branched from the branch points M and N in the oil passage connecting the accumulator 4, the rear-side control valve unit VR, and the front-side control valve unit VF. 17 and the rear-side fail valve 7, the size and weight of the device can be reduced.

That is, when the configuration is such that the two fail valves 7 and 17 are configured to bear the flow rate to the control valve units VR and VF, the large fail valves 7 and 17 that allow a large flow rate (about 20 liter / min) are used. On the other hand, both fail valves 7 and 17 need only bear the flow rate (1 liter / min or less) for switching to the pilot switching valves 9, 9, 19 and 19. Therefore, the size effect and the weight effect on the apparatus can be suppressed even though the two fail valves 7 and 17 are added to the system.

(Second Embodiment) First, the configuration will be described.

FIG. 5 is an overall system diagram showing a brake control device according to a second embodiment corresponding to the second invention.

Only the configuration different from that of the first embodiment will be described. The rear-side pilot switching valves 9, 9 and the front-side pilot switching valves 19, 19 are located downstream of the rear-side fail valve 7 and the front-side fail valve 17, respectively. The external hydraulic pressure supplied through the fail valves 7 and 17 is used as a valve operating pressure, and the master cylinder 1
And wheel cylinders 2, 2, 12, 12
At the time of command, the control pressure ports E of the control valve units VF, VR,
E and the wheel cylinders 2, 2, 12, and 12 are connected.

Next, the operation will be described.

[Fail Correspondence Control Operation] FIG. 6 is a flowchart showing the flow of a fail response control operation process performed by the controller (second fail correspondence control means h).
Equivalent).

That is, if only the rear brake control system fails at the time of braking, the flow proceeds from step 30 to step 31 to step 33 in the flowchart of FIG. 6, and the control is performed on the front side similarly to the first embodiment. Pressure and the master cylinder pressure are applied to the rear side, but if only the front brake control system fails during braking,
In the flowchart of FIG.
In step 35, an OFF command is output to both fail valves 7, 17, and the master cylinder pressure is applied to both the front side and the rear side.

The other operation is the same as that of the first embodiment, and the description is omitted.

Next, the effects will be described.

The following effect (1 ') corresponding to (1) of the first embodiment and the effect (3) of the first embodiment can be obtained.

(1 ') When a failure occurs only in the rear brake control system, the front side is set to the control pressure and the rear side is set to the master cylinder pressure. When a failure occurs only in the front brake control system, Since the rear side is a device that performs fail response control that uses the same master cylinder pressure as the same pressure, it is possible to suppress the driver's feeling of discomfort to the driver when a failure occurs only in the rear side brake control system and only for the front side brake control system. It is possible to achieve compatibility with prevention of rear wheel lock when a failure occurs.

Although the embodiments have been described with reference to the drawings, the specific configuration is not limited to the embodiments, and any changes or additions without departing from the gist of the present invention are included in the present invention. It is.

In the embodiment, the hydraulic control valve is of a type divided into two valves, a main valve and a pilot valve. However, one hydraulic control valve is disclosed in Japanese Patent Application Laid-Open No. 4-8767. It may have a control valve structure.

As described in JP-A-4-88767, a hydraulic control valve for performing TCS control using external fluid pressure as a signal pressure may of course be used.

[0080]

According to the first aspect of the present invention, in the brake control device in which the front and rear wheels have independent fail-safe functions, a failure occurs only in the rear brake control system. In this case, the control pressure is applied to the front side and the master cylinder pressure is applied to the rear side. If a failure occurs only in the front side brake control system, the first and second fail-response control means sets both the front and rear sides to the same pressure by the control pressure. The system is equipped with a brake system, which suppresses the driver from feeling uncomfortable when a failure occurs only in the rear brake control system and prevents rear wheel lock when a failure occurs only in the front brake control system. Is obtained.

According to the second aspect of the present invention, in a brake control device having independent fail-safe functions for two front and rear wheels, a failure occurs only in the rear brake control system. If the front side has a control pressure and the rear side has a master cylinder pressure, and a failure occurs only in the front side brake control system, a second failure correspondence control means which makes the front side and the rear side the same pressure by the master cylinder pressure is used. The device provided prevents both the driver from feeling uncomfortable braking when a failure occurs only in the rear brake control system and the prevention of rear wheel lock when a failure occurs only in the front brake control system. The effect that it can be achieved is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims showing a brake control device of a first invention.

FIG. 2 is a claim correspondence diagram showing a brake control device according to a second invention.

FIG. 3 is an overall system diagram showing a brake control device according to a first embodiment.

FIG. 4 is a flowchart showing a flow of a fail handling control operation performed by a controller of the first embodiment apparatus.

FIG. 5 is an overall system diagram showing a brake control device according to a second embodiment.

FIG. 6 is a flowchart showing a flow of a fail handling control operation performed by a controller of the device of the second embodiment.

FIG. 7 is an overall system diagram showing a brake control device of a first conventional example.

FIG. 8 is an overall system diagram showing a brake control device of a second conventional example.

[Explanation of symbols]

 a Master cylinder b, b 'Wheel cylinder c External hydraulic pressure source d Front-side hydraulic control valve d' Rear-side hydraulic control valve e Front-side fail valve e 'Rear-side fail valve f Front-side pilot switching valve f' Rear-side pilot switching Valve g 1st failure correspondence control means h 2nd failure correspondence control means

Continuation of the front page (56) References JP-A-4-88767 (JP, A) JP-A-2-237846 (JP, A) JP-A-4-163268 (JP, A) JP-A-63-20256 (JP) JP-A-5-178199 (JP, A) JP-A-58-26662 (JP, A) JP-A-60-12368 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B60T 13/66 B60T 13/12

Claims (4)

(57) [Claims] 1. A master cylinder for generating a master cylinder pressure corresponding to a brake operating force; each wheel cylinder provided in a braking device for each wheel and operated by a control pressure higher than the master cylinder pressure; An external hydraulic pressure source that generates hydraulic pressure independently, and two systems, a front wheel side (front side) and a rear wheel side (rear side), are each provided with a master cylinder pressure as a signal pressure. A front-side hydraulic control valve and a rear-side hydraulic control valve for inputting a force generated by a solenoid and adjusting an external hydraulic pressure supplied from an external hydraulic pressure source to a control pressure corresponding to a difference between the two inputs. In the control device, when only the rear brake control system fails, the master cylinder pressure is directly applied to the rear wheel cylinder and the front wheel cylinder is applied to the front wheel cylinder. When the control pressure from the front hydraulic control valve is applied and only the front brake control system fails, the control pressure from the rear hydraulic control valve is applied not only to the rear wheel cylinder but also to the front wheel cylinder. A brake control device comprising control means for handling one failure. 2. The brake control device according to claim 1, wherein a front-side fail valve and a rear-side fail valve that select and output an external hydraulic pressure or a return pressure according to an external command, and the front-side fail valve and a rear-side valve. A front-side pilot switching valve and a rear-side pilot switching valve for selecting the supply pressure to the wheel cylinder are provided with the output pressure of the fail valve as a valve operating pressure, respectively. Is connected to the rear wheel cylinder, the front hydraulic control valve is connected to the wheel cylinder when the external hydraulic pressure is selected, and the rear pilot valve is connected to the master cylinder and the wheel cylinder when the return pressure is selected. It has a structure to connect the rear side hydraulic control valve and wheel cylinder when selecting external hydraulic pressure. The first failure correspondence control means outputs an external hydraulic pressure selection command to the front failure valve and outputs a return pressure selection command to the rear failure valve when only the rear brake control system fails. A brake control device which outputs a return pressure selection command to a front-side fail valve and outputs an external hydraulic pressure selection command to a rear-side fail valve when only the side brake control system fails. 3. A master cylinder for generating a master cylinder pressure in accordance with a brake operation force; each wheel cylinder provided in a braking device for each wheel and operated by a control pressure higher than the master cylinder pressure; An external hydraulic pressure source that generates hydraulic pressure independently, and two systems, a front wheel side (front side) and a rear wheel side (rear side), are each provided with a master cylinder pressure as a signal pressure. A front-side hydraulic control valve and a rear-side hydraulic control valve for inputting a force generated by a solenoid and adjusting an external hydraulic pressure supplied from an external hydraulic pressure source to a control pressure corresponding to a difference between the two inputs. In the control device, when only the rear brake control system fails, the master cylinder pressure is directly applied to the rear wheel cylinder and the front wheel cylinder is applied to the front wheel cylinder. A second fail control means for applying the control pressure from the front hydraulic control valve and applying the master cylinder pressure to all the front and rear wheel cylinders when only the front brake control system fails. A characteristic brake control device. 4. The brake control device according to claim 3, wherein a front-side fail valve and a rear-side fail valve that select and output an external hydraulic pressure or a return pressure according to an external command, and the front-side fail valve and a rear-side valve. A front-side pilot switching valve and a rear-side pilot switching valve are provided, each of which sets the output pressure of the fail valve as a valve operating pressure and selects a supply pressure to a wheel cylinder, wherein the front-side pilot valve and the rear-side pilot valve return When the pressure is selected, the master cylinder and the wheel cylinder are connected, and when the external hydraulic pressure is selected, the hydraulic control valve and the wheel cylinder are connected. The second fail-corresponding control means is configured such that when only the rear brake control system fails, Outputs an external hydraulic pressure selection command to the front fail valve and Outputs down pressure selection command, when only the front side brake control system is fail, the brake control apparatus, characterized in that on both the front side fail valve and the rear side fail valve is a means for outputting a return pressure selection command.