JP2000344080A - Hydraulic braking device for vehicle - Google Patents

Abstract

(57) [Problem] To provide a hydraulic brake device for a vehicle which does not include an accumulator, has a reduced pump capacity, is small in size, has high performance, has high responsiveness and high reliability, and has a good pedal feel. SOLUTION: A brake device for supplying a hydraulic pressure from a hydraulic pump 1 to a wheel cylinder 3 to generate a braking force includes a master cylinder 7 and an opening / closing valve 9 for closing a master cylinder passage 8 when a brake pedal 13 is depressed. , A bypass passage 10, an on-off valve 11 in the passage, and a check valve 12
And the pump 1 supplies the hydraulic pressure during normal braking and braking by electric control. When the discharge amount of the pump 1 is insufficient due to sudden braking or the like, the opening and closing valve 10 is opened to supply the hydraulic pressure of the master cylinder 7 via the pump 1 so that the rise of the braking force is accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake device for generating a braking force by supplying a hydraulic pressure from a high pressure source, and more particularly to a hydraulic brake device for a vehicle.

[0002]

2. Description of the Related Art There has been an increasing number of hydraulic brake devices for vehicles that electrically control the effectiveness of the brake in order to control the advanced behavior of the vehicle. As an example of such an apparatus, for example, Japanese Patent Publication No. 2590825 includes a hydraulic pressure source constituted by a pump and an accumulator separately from a master cylinder that generates hydraulic pressure by pedal operation. Regardless, a brake device capable of supplying hydraulic pressure to a wheel-cylinder is disclosed.

[0003]

The above-mentioned conventional brake device includes an accumulator which requires a large space in a hydraulic pressure source for quickly raising a braking force, and the mountability in an engine room is deteriorated. Japanese Patent Application Laid-Open No. 9-20229 and Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 0-67311 discloses a method in which when a passage from a master cylinder to a wheel cylinder is blocked, the entire amount of brake fluid required for brake operation is covered by a pump discharge amount. Therefore, there is a disadvantage that a relatively large capacity pump or the like as a high pressure source is required. In addition, at the time of sudden braking, a delay in braking or the like becomes a problem, and it becomes difficult to obtain a good operation feeling. Accordingly, the present invention provides a hydraulic brake for a vehicle in which the responsiveness can be enhanced without using an accumulator and without increasing the capacity of a pump and the like, and having a fail-safe function important for vehicle braking. It is intended to provide a device.

[0004]

According to the present invention, there is provided a hydraulic brake device for generating a braking force by supplying a hydraulic pressure generated by a high-pressure source to a wheel cylinder. A master cylinder that generates a hydraulic pressure according to the pressure, a master cylinder passage connecting the master cylinder and the wheel cylinder, and an open / close valve that opens and closes the master cylinder passage, and a suction side of the high-pressure source that communicates with a reservoir. While providing a bypass passage connecting the passage and the master cylinder,
A check valve for preventing backflow from the bypass passage into the reservoir tank and an on-off valve for opening and closing the bypass passage are provided.

[0005]

According to the brake device of the present invention, when the brake pedal is depressed, the open / close valve of the master cylinder passage is closed to operate the high pressure source. Then, the hydraulic pressure from the high pressure source is introduced into the wheel cylinder to operate the vehicle brake.
Therefore, electrical control of the braking effect is possible.

Further, in this device, when the open / close valve of the master cylinder passage is of a normally open type, the master cylinder passage remains open when the electric control system fails, and hydraulic pressure is supplied from the master cylinder to the wheel cylinder. As a result, the pedaling force is controlled, and the fuel-safe function is also ensured.

When there is no failure in the electric control system of the apparatus, when the bypass passage is opened, the hydraulic pressure from the master cylinder is supplied to the suction side of the high-pressure source, and the hydraulic pressure is further increased by the high-pressure source, and the wheel pressure is increased. Supplied to the cylinder. Therefore, if the bypass passage is opened when the discharge amount of the high-pressure source is insufficient, the braking force can be quickly increased without an accumulator.

Further, depending on the degree of depression of the brake pedal, it may not be necessary to suddenly increase the braking force. At this time, the bypass can be closed and braking can be performed only by the high-pressure source.

When the hydraulic pressure is supplied from the master cylinder to the wheel cylinder via the high-pressure source, the master cylinder is completely disconnected from the discharge side of the high-pressure source during operation of the high-pressure source. The generated pulsation is not transmitted to the brake pedal, and deterioration of the pedal feel is also prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a hydraulic pump 1, which is a high-pressure source, is provided in the middle of a pipe 4 connecting a reservoir tank 2 and a wheel cylinder (vehicle brake) 3. The suction side and the discharge side of the hydraulic pump 1 are provided with a check valve for preventing a backflow of the brake fluid from the hydraulic pump 1 to the reservoir tank 2 and a reverse valve for preventing a backflow of the brake fluid from the wheel cylinder 3 to the hydraulic pump 1. Stop valves are arranged respectively. Here, these check valves are not shown because they are included in the pump.

The passage connecting the hydraulic pump 1 and the wheel cylinder 3 and the reservoir tank 2 are formed by the hydraulic pump 1
Are connected by a return passage 5 which bypasses. An electromagnetically driven normally closed on-off valve 6 is disposed in the return passage 5. A master cylinder 7 for generating a hydraulic pressure according to the brake operation force is connected to the wheel cylinder 3 by a master cylinder passage 8. An electromagnetically driven normally open on-off valve 9 is arranged in the master cylinder passage 8. The master cylinder 7 is connected to a passage connecting the hydraulic pump 1 and the reservoir tank 2 with a bypass passage 10. An electromagnetically driven on-off valve 11 is arranged in the bypass passage 10. Further, a check valve 12 for preventing a backflow of the brake fluid from the bypass passage 10 to the reservoir tank 2 is disposed closer to the reservoir than the junction with the bypass passage.
Also, a brake switch 14 for detecting the operation state of the brake pedal 13 is connected.

In the brake device having the above structure, when the brake pedal 13 is depressed, the brake switch 14
, The on / off valve 9 is closed and the hydraulic pump 1 is rotated. In this way, by adjusting the amount of liquid supplied from the hydraulic pump 1 to the wheel cylinder, an arbitrary amount of pressure increase can be set, and vehicle braking based on the driver's intention can be performed. When the pressure is increased by operating the wheel cylinder 3, first, the on-off valve 6 provided in the return passage is provided.
The hydraulic pump 1 is operated at a high speed in a state where is closed at the start of braking. At this time, the on-off valve 9 of the master cylinder passage 8 is closed, and the entire amount of the brake fluid pumped up by the pump 1 is supplied to the wheel cylinder 3 to increase the brake fluid pressure. As a result, after the brake is actuated and the vehicle speed falls below a predetermined value, the rotational speed of the hydraulic pump 1 is reduced or stopped, and in some cases the on-off valve 6 is opened.

Although hydraulic pressure is generated in the master cylinder 7 according to the operating force of the driver, the supply of brake fluid from the master cylinder via the master cylinder passage 8 is not possible because the on-off valve 9 is closed. Not done. As a result, the driver is separated from the pulsation generated by the hydraulic pump 1, and a good pedal feel can be obtained. Further, when a sudden braking is required, if the operation delay of the hydraulic pump 1 becomes a problem, the on-off valve 11 of the bypass passage 10 is used.
And brake fluid pressure is supplied from the master cylinder 7 to the suction circuit of the hydraulic pump 1 to prevent delay. At the end of braking, the operation of the hydraulic pump 1 is terminated, and the hydraulic pressure of the wheel cylinder 3 is returned from the return passage 5 to the reservoir tank 2.
At this time, the on-off valve 9 may be opened to return to the circuit on the master cylinder side.

The amount of liquid supplied to the wheel cylinder is determined, for example, by detecting the operating force of the brake pedal by the driver and the hydraulic pressure of the wheel cylinder, and adjusting the rotational speed of the hydraulic pump 1, adjusting the torque of the hydraulic pump drive motor, or By controlling the opening and closing of the on-off valve 6, it is possible to adjust the wheel cylinder hydraulic pressure to a value corresponding to the operating force.

[0015] Whether or not the discharge amount of the pump is insufficient is determined by whether or not the change rate of the operating force by the driver or the master cylinder fluid pressure exceeds a predetermined value (in the case of sudden braking, the change rate is large). When it is determined that the pump discharge amount is insufficient (of course, the determination
An on-off valve 11 is provided by an electronic control unit (not shown).
If you open it, it will exhibit high response even during sudden braking.

Next, an embodiment of a specific hydraulic brake circuit in which an ABS (anti-lock brake control) device is incorporated in the vehicle hydraulic brake device having the above basic configuration will be described with reference to FIG. The vehicle hydraulic brake device shown in FIG.
One of the two hydraulic circuits of the tandem master cylinder 15 is shown.
Denotes a hydraulic brake device for the front left and right wheels (or the rear left and right axes) or the left front wheel and the right rear wheel (the right front wheel and the left rear wheel). The hydraulic pressure in the other pressure generating chamber of the tandem master cylinder 15 is supplied to a wheel brake of another system (not shown). The electronic control unit and the wheel speed sensor included in the ABS are not shown.

A hydraulic circuit having the following configuration is provided between the tandem master cylinder 15, the wheel brakes 16, 17 and the reservoir tank 18 in order to perform antilock control of the hydraulic pressure of the wheel cylinders 16, 17. The hydraulic circuit includes first normally open / close valves 19 and 20 for stopping supply of hydraulic pressure from the tandem master cylinder 15 to the wheel cylinders 16 and 17, and wheel cylinders 16 and 17.
The normally open second on-off valves 21 and 22 for discharging the fluid pressure to the reservoir tank 18, and the first on-off valve 19, which is driven by a motor to drive the brake fluid in the reservoir tank 18,
A hydraulic pump 24 that discharges to a master cylinder passage 23 between the tandem master cylinder 15 and the tandem master cylinder 15, a bypass passage 25 that connects a suction side passage of the hydraulic pump 24 to the tandem master cylinder 15, and a hydraulic pump 24 that is disposed in the bypass passage 25. The open / close valve 26 and the bypass passage 25
An on-off valve 2 that opens and closes at a position closer to the master cylinder 15 than the junction of the discharge side passage of the hydraulic pump with the circuit
7, a return passage 28 for communicating the discharge port of the hydraulic pump 24 with the reservoir tank 18,
And a check valve 30 for preventing backflow from the bypass passage 25 to the reservoir tank 18. The on-off valves are all electromagnetically driven valves. It should be noted that the suction side and the discharge side of the hydraulic pump 24
A check valve for preventing backflow of brake fluid from the brake fluid to the reservoir 18 and a check valve for preventing backflow of brake fluid from the wheel brakes 16 and 17 to the pump 24 (both not shown) are arranged. Further, in order to detect the brake operation amount and the operation force input from the brake pedal 31, the pedaling force sensor 32 and the pressure sensor 33 which detects the hydraulic pressure generated by the tandem master cylinder 15, and to prevent the so-called plate depression of the brake. May be provided with a stroke simulator 34 and a stroke sensor 35 for detecting a pedal stroke generated thereby.

On the other hand, a pressure sensor 36 is also provided on the brake side, and the hydraulic pressure (brake 1
The control of the braking force may be performed by detecting the hydraulic pressures generated at 6, 6 and 17).

When the brake pedal 31 is operated in the vehicle hydraulic brake device having such a structure, the on-off valve 27 is closed by a signal from the pedaling force sensor 32, and the hydraulic pump is operated to discharge the hydraulic pressure therefrom. Is wheel cylinder 1
6, 17 are supplied.

In the illustrated brake device, braking is performed by supplying hydraulic pressure from a pump, and the braking force is controlled as necessary. Therefore, the discharge hydraulic pressure supplied to the wheel cylinder is not only proportional to the operation amount of the brake pedal, but also in the case of automatic braking or traction control that pressurizes the brake system without operation of the brake pedal. Can be applied. Also, the present invention can be applied to a case of regenerative cooperative brake control used in an electric vehicle or the like, in which the hydraulic braking force is reduced according to the regenerative braking to increase the regenerative efficiency.

The following is an example of the case where the antilock control is executed.

Now, when the electronic control unit detects the tendency to lock the wheels and issues a pressure reduction command therefrom, the first opening / closing valves 19, 20 of the wheels exhibiting the tendency to lock while the hydraulic pump 24 is operating. Is closed, the second on-off valves 21 and 22 are opened, the brake fluid in the wheel cylinders 16 and 17 is discharged to the reservoir tank 18, and the fluid pressure in the wheel cylinders 16 and 17 decreases. When the pressure is reduced and the wheel tends to be locked and a re-pressurization command is issued from the electronic control unit, the second on-off valves 21 and 22 are closed, the first on-off valves 19 and 20 are opened, and the fluid from the hydraulic pump 24 is opened. Pressure is again introduced into the wheel cylinders 16,17. If the command from the electronic control unit changes to holding, both the first and second on-off valves are closed and the hydraulic pressure of the wheel cylinders 16 and 17 is held. Note that the wheel may show either one of the locking tendencies, and at that time, the above-described control is performed on one of the wheels having the locking tendency. Further, a function of maintaining the hydraulic pressure is added as needed.

This brake device also has an on-off valve 2 when it is determined that the pump discharge is insufficient due to a sudden braking operation or the like.
6 is opened, and the hydraulic pressure from the tandem master cylinder 15 is supplied to the suction side circuit of the hydraulic pump 24. Then, the hydraulic pump pumps up the brake fluid from the master cylinder and supplies it to the wheel cylinder. Therefore, the rising of the braking force is abrupt, and no response delay occurs.

As described above, in the present brake device, the hydraulic pump 24 is shared between the antilock control and the normal brake control. When the brake pedal is depressed in a normal state of the electric control system, the on-off valve 27 is closed and the master cylinder 15 is disconnected from the discharge side of the hydraulic pump 24. Does not deteriorate.

Further, in the control performed by the pedaling brake when the normal brake control cannot be executed due to the failure of the electric control system, if a vacuum or hydraulic booster is added to the master cylinder portion, the mechanical control can be performed even in the above case. Boost control can be configured to survive.

[0026]

As described above, the hydraulic brake device according to the present invention can perform braking by the pedaling force when the electric control system fails and braking by the pump necessary for electrically controlling the braking effect. Yes, and since the hydraulic pressure of the master cylinder can be supplied to the wheel cylinder via the pump and braking by both the pump and the pedaling force is possible,
It is possible to realize a hydraulic brake device for a vehicle which does not include an accumulator and has a small pump capacity, high performance, high responsiveness, high reliability and good pedal feel.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a basic configuration of a hydraulic brake device according to the present invention.

FIG. 2 is a circuit diagram of a hydraulic brake device including an ABS device.

[Explanation of symbols]

 1, 24 Hydraulic pump 2, 18 Reservoir tank 3, 16, 17 Wheel cylinder 4 Piping 5, 28 Return passage 6, 29 Return passage open / close valve 7, 15 Master cylinder 8, 23 Master cylinder passage 9, 27 Master cylinder passage On-off valve 10, 25 Bypass passage 11, 26 By-pass passage on-off valve 12, 30 Check valve 13, 31 Brake pedal 14 Brake switch 19, 20 First on-off valve 21, 22, Second on-off valve 32 Treading force sensor 33, 36 Pressure Sensor 34 Stroke simulator 35 Stroke sensor

Claims (1)

[Claims] 1. A hydraulic brake device for generating a braking force by guiding hydraulic pressure generated by a high-pressure source to a wheel cylinder,
An apparatus comprising: a fluid passage that communicates the high-pressure source with both the wheel cylinder and the reservoir tank; and a flow control unit that controls an amount of liquid supplied from the high-pressure source to the wheel cylinder. A master cylinder that generates pressure, a master cylinder passage that connects the master cylinder and the wheel cylinder, an on-off valve that opens and closes the master cylinder passage, a suction-side passage of a high-pressure source that communicates with the reservoir tank, and the master cylinder. A hydraulic brake device for a vehicle, comprising: a bypass passage for communication; a check valve for preventing backflow of liquid from the bypass passage to a reservoir tank; and an on-off valve for opening and closing the bypass passage.