JP2001213296A - Vehicular hydraulic braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance responsiveness of a hydraulic braking device at a rapid pressurization or the like by suppressing an increase of a pedal stroke and preventing deterioration of a pedal feel, in a device when stroke simulator is provided for generating a braking hydraulic pressure by a power-driven pump stopping a pressure supply from a master cylinder when an electric control system thereof is normal. SOLUTION: An alternative path 19 is provided for communicating the master cylinder 1 and wheel cylinders 2A, 2B bypassing an on-off valve 3 which is usually closed during braking, and a check valve 20 and a shut-off valve 21 to be opened at a rapid pressurization are provided in the alternative path 19. A throttle 22 is provided in a circuit from a back pressure chamber 4b in the stroke simulator 4 to a reservoir 8. A first suction path 23 extending from a circuit before the throttle 22 to a suction port of a pump 7 and a second suction path 24 communicating the reservoir 8 to the first suction path 23 are provided, a check valve 25 being provided in the second suction path 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fuel-supplying master cylinder in addition to a power-driven pump serving as a main hydraulic pressure source. The present invention relates to an improvement plan of a hydraulic brake device for a vehicle in which a hydraulic pressure is also supplied from a master cylinder in order to enhance responsiveness during braking).

[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 a device, for example, Japanese Patent Publication No. 2590825 has 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 that can supply hydraulic pressure to the wheel cylinder is disclosed, but since this device includes an accumulator that takes up space,
Poor mountability in engine room.

Further, an apparatus for generating a replenishing brake fluid only by a pump when the wheel cylinder pressure is increased or decreased by electronic control is disclosed in JP-A-9-20229 or JP-A-10-67.
Although these devices have been proposed in Japanese Patent Publication No. 311 or the like, when the communication passage between the master cylinder and the wheel cylinder is blocked, the pump must cover the entire amount of brake fluid required for braking. A large capacity pump is required. Also, a delay in boosting pressure at the time of rapid pressurization or low temperature becomes a problem, and the braking distance is also increased.

[0004] Therefore, there has been proposed a brake device which addresses the above-mentioned problems.

FIG. 2 is a basic circuit diagram of the device. As shown in the figure, the master cylinder 1 and the wheel cylinder 2
The electromagnetically driven on-off valve 3 and the stroke simulator 4 are inserted in the communication passage between A and 2B (the symbols A and B are used for convenience and may be omitted in the following description). A control valve for controlling the wheel cylinder pressure based on a command from an electronic control unit (not shown) (the on-off valves 5A and 5B for pressurization and the on-off valves 6A and 6B for pressure reduction);
Open / close valve 9 for a return passage from the discharge port of a pump 7 (the electric hydraulic pump in the figure) to the suction side connected to a reservoir 8
A bypass passage 10 for communicating the suction side of the pump 7 with the master cylinder 1, an on-off valve 11 for opening and closing the bypass passage 10, and a check valve 12 for preventing a liquid flow from the bypass passage 10 to the reservoir 8. ing. The on-off valves 5 and 6 are provided to enable antilock control.
It is not an essential element of the present invention.

Reference numerals 13A and 13B denote pressure sensors for detecting hydraulic pressure, 14 is a relief valve for preventing excessive pressure increase, 15 is a throttle for silencing, and 16 is a silencer. Although the relief valve 14, throttle 15 and silencer 16 are newly added to the previously proposed circuit, these are only preferred elements.

Here, the back pressure chamber 4b of the stroke simulator 4 is connected to the reservoir 8 to keep the chamber in a wet state.

[0008]

In the brake system shown in FIG. 2, the brake fluid pressure during normal operation (when the electric control system is normal) is generated by the pump 7, and the pump pressure is insufficient when the pump alone is used. At the time of pressurizing or the like, the hydraulic pressure is also supplied from the master cylinder 1 to the wheel cylinder 2.

[0009] The hydraulic pressure supply from the master cylinder
However, if this method is adopted, the pulsation caused by the operation of the pump or the intermittent opening and closing of the on-off valve 3 is transmitted to the brake pedal 17, and the pedal feel deteriorates. Also,
When the on-off valve 3 is kept open, kickback of the brake pedal occurs when the hydraulic pressure on the wheel cylinder exceeds the master cylinder pressure (the hydraulic pressure generated in the master cylinder).

The apparatus shown in FIG. 2 is provided with a bypass 10 having an on-off valve 11 to supply the hydraulic pressure from the master cylinder 1 via the pump 7 in order to eliminate the problem, but the on-off valve 11 is opened. At the time of sudden pressurization or the like, the check valve 12 closes and the pump 7 stops sucking liquid from the reservoir 8, so that the amount of replenishing liquid from the master cylinder increases and the pedal stroke (stroke of the brake pedal 17) is reduced. Is larger than at the time of gentle pressurization in which is closed.

In addition, since the pump intermittently pumps the liquid from the master cylinder, the pulsation is transmitted to the brake pedal. Further, when the throttle 15 is provided on the discharge side of the pump 7 as a measure against noise, the effect of the rapid pressurization is weakened by the influence of the throttle.

The disadvantages of the present invention have been eliminated to eliminate delays in boosting pressure and deterioration of the pedal feel during sudden pressurization, and at the same time, to enhance pump responsiveness during rapid pressurization and low temperature to improve responsiveness. It is an object to provide a hydraulic brake device.

[0013]

In order to solve the above-mentioned problems, the present invention provides a master cylinder for generating a hydraulic pressure according to a brake operating force, a power-driven pump, and a pump for driving a master cylinder and a wheel cylinder. An on-off valve provided in a communication passage, a stroke simulator in which a main chamber is connected to a communication passage between the on-off valve and the master cylinder, and a back pressure chamber in communication with a reservoir. In a vehicle hydraulic brake device for supplying brake fluid pressure to a wheel cylinder from a pump by closing a valve, a bypass is provided for bypassing the on-off valve to communicate the master cylinder and the wheel cylinder. A check valve or a relief valve that allows only liquid flow from the cylinder to the wheel cylinder, and a shutoff valve. Further, in the apparatus shown in FIG. 2, the liquid discharged from the back pressure chamber of the stroke simulator returns to the reservoir and is not used effectively. In the present invention, the reflux liquid is also used for improving the response. For this purpose, a throttle is provided in a circuit connecting the back pressure chamber and the reservoir of the stroke simulator, and a first suction path and a reservoir from a circuit between the throttle and the back pressure chamber to a suction port of the pump are connected to the first suction path. And a check valve for allowing only the liquid flow from the reservoir to the pump is provided in the second suction path.

[0014]

In the brake device of the present invention, the shutoff valve of the bypass is opened at the time of rapid pressurization or the like where the supply of the hydraulic pressure is insufficient with the pump alone, and the brake fluid from the master cylinder passes through the bypass to the wheel cylinder. Supplied.

In the device according to the present invention, the throttle function provided between the back pressure chamber of the stroke simulator and the reservoir increases the viscosity of the brake fluid and the step of the brake pedal. As the discharge flow rate increases, the hydraulic pressure of the circuit before the throttle increases, and the circuit before the throttle is connected to the suction port of the pump via the first suction path. The pressurized brake fluid is pumped by the pump, thereby improving the suction efficiency of the pump.

Therefore, during rapid pressurization or the like, the liquid from the master cylinder is added to the total amount of liquid discharged from the pump whose suction efficiency has been increased, and is supplied to the wheel cylinder, so that the pressure rises faster.

When the wheel cylinder pressure exceeds the master cylinder pressure, the check valve of the bypass is closed, so there is no need to open and close the shutoff valve, and the pedal feel does not deteriorate. Closing the bypass check valve prevents kickback of the pedal when the wheel cylinder pressure rises.Furthermore, when the check valve of the bypass circuit closes, the supply of liquid from the master cylinder stops. Can be kept small.

[0018]

FIG. 1 shows an embodiment of a hydraulic brake device for a vehicle according to the present invention. This figure shows one of the hydraulic circuits normally provided in two separate systems. The wheel cylinders 2A and 2B include front left and right wheels, rear left and right wheels, left front wheel and right rear wheel, right front wheel and left rear wheel The wheel belongs to one of the wheel brakes.

The master cylinder 1 is provided to make it possible to perform braking by the pedaling force when the electric control system of the device fails. In order to prevent a decrease in the braking force due to the braking by the pedaling force, the master cylinder 1 The operation force of 17 is proportionally amplified by a vacuum booster 18 to generate a hydraulic pressure.

The brake device of FIG. 1 is a modification of the device of FIG. 2 described above, and therefore, the same portions except for the changed portions are denoted by the same reference numerals and the description thereof will not be repeated.

On the suction side and the discharge side of the pump 7, a check valve for preventing the backflow of the brake fluid to the reservoir 8 and a check valve for preventing the backflow of the brake fluid from the wheel cylinder 2 to the pump 7 are provided. However, these check valves are not shown because they are included in the pump 7.

The brake device shown in FIG. 1 is provided with a bypass 19 for connecting the master cylinder 1 and the wheel cylinder 2 to bypass the on-off valve 3 instead of the bypass 10 and the on-off valve 11 of the device shown in FIG. Further, the bypass 19 is provided with a check valve 20 for allowing only the liquid flow from the master cylinder 1 to the wheel cylinder 2 and a shutoff valve (in the figure, an electromagnetically driven on-off valve) 21. A throttle 22 is provided in a circuit connecting the back pressure chamber 4b and the reservoir 8 of the stroke simulator 4, and a first suction path from a circuit before the throttle (on the back pressure chamber side of the throttle 22) to the suction port of the pump 7 is further provided. 23, and a second suction path 24 for communicating the reservoir 8 with the first suction path 23,
The second suction passage 24 is provided with a check valve 25 that allows only the liquid flow from the reservoir 8 to the pump 7, which is different from the apparatus of FIG.

In the brake device having the above structure, when the brake pedal 17 is depressed, the on-off valve 3 is closed and the pump 7 is rotated by a signal from a brake switch (not shown) and / or a pressure sensor 13A. In this way, by adjusting the amount of liquid supplied from the pump 7 to the wheel cylinder 2, an arbitrary amount of pressure increase can be set, and vehicle braking can be performed based on the driver's intention.
In order to increase the pressure by operating the wheel cylinder 2, first, the pump 7 is operated at a high speed with the on-off valve 9 in the return passage closed at the start of braking. At this time, the on-off valve 3 in the communication passage from the master cylinder is closed, and the entire amount of the brake fluid pumped by the pump 7 is supplied to the wheel cylinder 2 to increase the brake fluid pressure. Accordingly, when the output of the pressure sensor 13B on the wheel cylinder side reaches a predetermined pressure, the rotation speed of the pump 7 is reduced or stopped, and in some cases, the on-off valve 9 is opened.

Although a hydraulic pressure is generated in the master cylinder 1 in proportion to the operating force of the driver, the brake fluid is not supplied from the master cylinder via the on-off valve 3 because the on-off valve 3 is closed. . As a result, the driver is separated from the pulsation generated by the pump 7, and a good pedal feel can be obtained.

When a sudden pressure increase due to a delay in the operation of the pump 7 or the like becomes a problem when sudden braking is required, the detour 1
9 is opened to supply the brake fluid from the master cylinder 1 to the wheel cylinder 2. If the depression of the brake pedal is sharp, the pressure in the first suction passage 23 increases and the pump 7 pumps up the discharged liquid from the stroke simulator 4, so that the pump suction efficiency increases and the pump discharge pressure also increases quickly. Therefore, the boosting delay is prevented by the synergistic effect of the two, and high responsiveness is exhibited. At the end of braking, the operation of the pump 7 is terminated, and the hydraulic pressure of the wheel cylinder 2 is returned to the reservoir 8 by opening the on-off valve 9. The on-off valves 5 and 6 in the figure are arranged for performing antilock control. At this time, if necessary, the on-off valve 6 may be opened to return the pressure to the reservoir sooner. On the other hand, in the low pressure range, the on-off valve 3 is opened to discharge a part of the discharged liquid to the master cylinder 1.
It may be returned to the side.

The amount of liquid supplied to the wheel cylinder 2 is determined, for example, by detecting the operating force of a brake pedal by a driver and the hydraulic pressure of the wheel cylinder, adjusting the rotation speed of the pump 7, adjusting the torque of the pump drive motor, or adjusting the on-off valve 6. , 9 can be adjusted in such a way that the wheel cylinder pressure is set to a value corresponding to the operating force. Although only one of the two hydraulic circuits is shown in the figure, it is also possible to obtain a different hydraulic pressure for each system by changing the degree of opening and closing of the on-off valves 9 and 6 for each system.

Whether the pump discharge amount is insufficient is determined by whether the change rate of the operating force by the driver or the master cylinder pressure exceeds a predetermined value (in the case of sudden braking, the change rate is large), and the like. Can be determined by comparing the pressure sensors 13A and 13B. If the shut-off valve 21 is opened when it is determined that the pump discharge amount is insufficient (this determination is, of course, performed by an electronic control unit (not shown)), high responsiveness is exhibited even during a sudden braking. Generally, the shutoff valve 21 is closed when the pressure on the wheel cylinder side is sufficiently increased by comparing the pressure sensors 13A and 13B. However, since the check valve 20 is provided in the bypass 19, the shutoff valve 21 is kept open. However, kickback of the brake pedal does not occur. Further, when the check valve 20 is closed due to an increase in the wheel cylinder pressure, the liquid supply from the master cylinder is stopped, so that the brake pedal 17 does not become unnecessarily large, and a good pedal feel is maintained. Rapid pressurization becomes possible.

The illustrated brake device has opening / closing valves 5 and 6 for controlling the pressure increase and decrease of the wheel cylinder pressure, and pressure sensors 13A and 13B for detecting the master cylinder pressure and the hydraulic pressure of the discharge side circuit of the pump, respectively. In addition, by providing a brake switch, an electronic control unit, a wheel speed sensor (all not shown), etc., 1) the hydraulic pressure supplied from the pump to the wheel cylinder is controlled by the operation amount (operating force) of the brake pedal. 2) anti-lock control when the wheels show a tendency to lock, 3) pressurizing the brake system for the purpose of deceleration and vehicle body posture control without operation of the brake pedal. Automatic braking and traction control; 4) Regenerative cooperative brake that increases the regenerative efficiency by reducing the hydraulic braking force according to the regenerative braking used in electric vehicles, etc. Control, 5) brake assist control for generating the braking force or braking force proportional to the brake pedal operation amount of the driver, such as during sudden braking, 6) optimally adjust the braking force distribution between the front and rear wheels EB
Various fluid pressure controls such as D control can be performed.

When a relief valve that opens when a predetermined hydraulic pressure difference is generated is used as the check valve 20 in FIG. 1, the chance that the pulsation generated by the pump is transmitted to the brake pedal can be further reduced.

As the stroke simulator 4,
If the amount of liquid discharged from the back pressure chamber 4b is amplified with respect to the amount of liquid from the master cylinder 1 introduced into the main chamber 4a (the amount of liquid can be amplified by a well-known hydraulic amplifier or the like),
The suction efficiency of the pump is further increased, and the amount of liquid replenishment from the master cylinder is reduced, so that the brake pedal can be made smaller.

[0031]

As described above, according to the present invention, the brake fluid to be supplied from the master cylinder to the wheel cylinder is supplied to the check valve and the shut-off valve at the time of rapid pressurization where the supply of the hydraulic pressure by the pump alone is insufficient. To the discharge side of the pump through the detour, and at the same time, raise the pressure of the brake fluid discharged from the back pressure chamber of the stroke simulator with the throttle, and pump it up to increase the suction efficiency of the pump. Therefore, even in a device that does not include an accumulator and has a reduced pump capacity, high response can be ensured by eliminating a pressure rise delay at the time of rapid pressurization or the like.

When the wheel cylinder pressure exceeds the master cylinder pressure, the check valve of the bypass is closed and the supply of the liquid from the master cylinder is stopped thereafter. . Further, since the check valve is provided in the detour, there is no need to intermittently open and close the shutoff valve of the detour, and deterioration of the pedal feel can be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a hydraulic brake device according to an embodiment.

FIG. 2 is a circuit diagram of a hydraulic brake device to be improved;

[Explanation of symbols]

 Reference Signs List 1 master cylinder 2A, 2B wheel cylinder 3 on-off valve 4 stroke simulator 4b back pressure chamber 5A, 5B on-off valve 6A, 6B on-off valve 7 pump 8 reservoir 9 on-off valve 12 check valve 13A, 13B pressure sensor 14 relief valve 15 throttle 16 Muffler 17 Brake pedal 18 Vacuum booster 19 Detour 20 Check valve 21 Shutoff valve 22 Throttle 23 First suction path 24 Second suction path 25 Check valve

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (1)

[Claims] A master cylinder for generating a hydraulic pressure corresponding to a brake operating force; a power-driven pump; an on-off valve provided in a communication passage between the master cylinder and the wheel cylinder; A vehicle having a stroke simulator in which a back pressure chamber communicates with a reservoir in a communication passage between the pumps and supplies the brake fluid pressure from a pump to a wheel cylinder by closing the on-off valve when the electric control system of the device is normal. In the hydraulic brake device, a detour is provided to bypass the on-off valve and communicate the master cylinder and the wheel cylinder, and the detour includes a check valve or a relief valve that allows only the liquid flow from the master cylinder to the wheel cylinder. A shutoff valve is provided, a throttle is provided in a circuit connecting the back pressure chamber of the stroke simulator and the reservoir, and a circuit between the throttle and the back pressure chamber is provided. A first suction passage and the reservoir leading to the inlet of the pump from the first
A hydraulic brake device for a vehicle, comprising: a second suction passage communicating with a suction passage; and a check valve for allowing only a liquid flow from a reservoir to a pump in the second suction passage.