JPH0612237U - Vehicle brake fluid pressure control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To secure the braking force by adequately compensating the brake fluid for the master cylinder, reduce the size and weight of the entire device, and reduce driving noise and vibration. [Structure] A main passage 5 for supplying the brake fluid pressure in the master cylinder 1 to each wheel cylinder 3, and the brake fluid in the wheel cylinder 3 is returned from the two reservoir mechanisms 7, 8 to the main passage 5 during antilock control. A recirculation passage 6, and a storage chamber 23 separated by each piston 22, 22;
23 is connected to the intermediate end of the branch passage 6, and the pistons 22, 22 are connected to the hydraulic chambers 24, 24 via the supply passage 26.
Connect an accumulator 17 that supplies hydraulic pressure for operation,
Further, the first and second check valves 11 to 14 are provided in the branch passages 6a and 6b and the downstream portions 6c and 6d, and the supply passage 2 is provided.
6 and the return passage 27 are provided with switching solenoid valves 28 and 29 for switching between the passages 26 and 27.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vehicle brake fluid pressure control device.

[0002]

[Prior art]

 2. Description of the Related Art Recently, automobile brake fluid pressure control devices have adopted, for example, a closed circulation type antilock brake system that controls brake fluid pressure in order to prevent wheel lock during vehicle braking.

This anti-lock brake system uses a master cylinder equipped with a hydraulic booster and a wheel cylinder when there is a risk that the wheels will lock due to the friction coefficient of the road surface, such as during sudden braking of the vehicle. The communicating main passage is closed by the solenoid valve for increasing pressure, and the return passage communicating between the wheel cylinder and the reservoir is opened by the solenoid valve for reducing pressure, and the brake fluid in the wheel cylinder is released to the atmosphere of the hydraulic booster. It is returned to the reservoir tank of No. 1 to reduce the pressure, and then holding and re-pressurizing operations are repeated to control the wheels to maintain the optimum slip ratio. The brake fluid stored in the reservoir tank during the anti-lock control is returned to the hydraulic pressure circuit of the hydraulic booster by the hydraulic pump.

The hydraulic booster has a relatively simple structure such as the hydraulic pump and an auxiliary pressure control valve. During the antilock control, the hydraulic booster acts on the piston of the master cylinder in proportion to the depression force of the brake pedal. A pressure is applied (see Japanese Patent Application Laid-Open No. 61-171654, etc.).

[0005]

[Problems to be solved by the device]

 However, in the above-mentioned conventional brake fluid pressure control device, as described above, during antilock control, the brake fluid pressure in the wheel cylinder is directly flown into the reservoir tank by the opening operation of the pressure reducing solenoid valve, and pressure reduction control is performed. It is carried out. Therefore, if the hydraulic pipe from the wheel cylinder to the reservoir tank is cracked or cut for some reason, the brake fluid flowing out of the wheel cylinder leaks to the atmosphere. Then, the amount of brake fluid in the brake fluid pressure circuit may decrease, and sufficient braking force may not be obtained.

[0006]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional circumstances, and includes a main passage for supplying brake fluid pressure in a master cylinder equipped with a reservoir tank to a wheel cylinder of each wheel, and the wheel cylinder during antilock control. In a brake fluid pressure control device for a vehicle, comprising: a return passage for returning the brake fluid pressure therein to the main passage via a reserve mechanism, the reserve mechanism is provided in each branch passage of the return passage, and Each piston that slides inside each cylinder of each reserve mechanism separates the storage chamber from the hydraulic chamber, and connects each storage chamber with an intermediate end of each branch passage, while each hydraulic chamber Is connected to a pressure generating means for supplying the hydraulic pressure for operating each piston through a supply passage, and a wheel cylinder is provided at a front and rear position of the reserve mechanism in the branch passage. A pair of check valves that allow the inflow of the brake fluid only in the main passage direction are provided in series, and the check valve is returned between the return passage for returning the brake fluid in the hydraulic chamber to the reservoir tank and the supply passage. The feature is that a switching valve for switching between both passages is provided.

[0007]

[Action]

 According to the present invention having the above-described structure, the brake fluid in the wheel cylinder flows into the reservoir chamber of each reserve mechanism through each first check valve provided in each branch passage of the return passage during antilock control. When stored temporarily, the switching valve operates to close and close the return passage and open the supply passage. Therefore, the high hydraulic pressure from the pressure generating means is supplied into the hydraulic chambers to press the pistons toward the storage chambers and discharge the brake fluid from the storage chambers to the downstream side of the return passage. Therefore, the brake fluid is quickly returned to the master cylinder side of the main passage through each second check valve. Then, the switching valve opens the return passage and closes the supply passage, so that the brake fluid in each hydraulic chamber is returned to the reservoir tank through the return passage. Therefore, each piston slides toward each hydraulic chamber to increase the volume of each storage chamber. That is, the continuous switching operation of the switching valve causes the reserve mechanism to perform a pumping action, and the depressurized brake fluid is forcibly and promptly returned to the master cylinder. As a result, even if the return passage is broken, the return passage and the return passage are separated by the piston of the reserve mechanism, so sufficient brake fluid is compensated for in the master cylinder. Deterioration is prevented.

Moreover, since the two reservoir mechanisms are provided, the pump action can be performed alternately, and the response of the brake fluid supply to the master cylinder is improved.

[0009]

【Example】

 FIG. 1 shows an embodiment of a vehicle brake fluid pressure control device according to the present invention, which is provided with an antilock brake system A having a closed circulation fluid pressure circuit and a hydraulic booster system B. For convenience of explanation, the brake fluid pressure circuits on the left and right sides of the front wheels will be described.

That is, in FIG. 1, reference numeral 1 is a master cylinder that generates brake fluid pressure in accordance with the amount of depression of a brake pedal 2, reference numeral 3 is a wheel cylinder on one of the left and right front wheels, and the master cylinder 1 is a hydraulic booster system B. It is equipped with a reservoir tank 4 that is open to the atmosphere and is communicated with the wheel cylinder 3 through a main passage 5. On the other hand, the wheel cylinder 3 communicates with a pair of reserve mechanisms 7 and 8 via branch passages 6a and 6b of a return passage 6 whose one end is connected to the downstream side of the main passage 5. Further, the main passage 5 is provided with a normally open type solenoid valve 9 for increasing pressure, which connects or shuts off the master cylinder 1 and the wheel cylinder 3. On the other hand, on the upstream side of the return passage 6, there is provided a normally closed pressure reducing solenoid valve 10 that connects or disconnects the wheel cylinder 3 and the two reserve mechanisms 7 and 8.

Further, in the return passage 6, the downstream portions 6c and 6d connected to the respective branch passages 6a and 6b are connected to the upstream side of the pressure increasing solenoid valve 9 of the main passage 5, respectively. Further, the respective branch passages 6a, 6b are provided with first check valves 11, 12 for allowing the inflow of the brake liquid only from the wheel cylinder 3 in the directions of the reserve mechanisms 7, 8 while the respective downstream portions are provided. Second check valves 13 and 14 which allow the inflow of the brake fluid from the reserve mechanisms 7 and 8 only in the direction of the main passage 5 are provided on the 6c and 6d.

The hydraulic booster system B includes a circulation passage 15 that circulates between the reservoir tank 4 and the master cylinder 1 via a control valve mechanism, and a hydraulic pump 16 provided on the upstream side of the circulation passage 15. An accumulator 17 as pressure generating means for accumulating the brake fluid pressure fed from the fluid pressure pump 16 and a relief valve provided in the relief passage 18 to relieve the brake fluid when the accumulated pressure of the accumulator 17 overflows. 19 and a check valve 20 provided on the downstream side of the circulation passage 15.

The reserve mechanisms 7 and 8 include pistons 22 and 22 slidably provided in the cylinders 21 and 21, storage chambers 23 and 23 separated by the pistons 22 and 22, and hydraulic pressure. The chambers 24, 24 and the compression coil springs 25, 25, which are elastically mounted in the hydraulic chambers 24, 24 and urge the pistons 22, 22 toward the storage chambers 23, 23, are provided.

The pistons 22, 22 are formed in a stepped diameter shape, and the second pressure receiving surface 22b facing the hydraulic chambers 24, 24 side from the first pressure receiving surfaces 22a, 22a facing the storage chambers 23, 23 side. , 22b are set larger. The storage chambers 23, 23 communicate with the wheel cylinder 3 and the master cylinder 1 via the branch passages 6a, 6b and the downstream portions 6c, 6d of the return passage 6, while the hydraulic chambers 24, 24 communicates with the circulation passage 15 through a supply passage 26 and a return passage 27. That is, the supply passage 26 has an upstream end connected to the downstream side of the accumulator 17 of the circulation passage 15, and a return passage 27 has a downstream end connected to the downstream side of the pump 16 of the circulation passage 15. In addition, three-port two-position type first and second switching solenoid valves 28 and 29 are provided near the reservoir mechanisms 7 and 8 in both the passages 26 and 27.

The switching solenoid valves 28 and 29 are alternately switched by a control current output from a controller (not shown) via a drive circuit, and the first switching solenoid valve 28 is connected to the supply passage 26 and the hydraulic pressure. When the chambers 24, 24 are communicated with each other, the second switching solenoid valve 29 communicates the return passage 27 with the hydraulic chambers 24, 24 so that the alternate switching operation is continuously performed. ing. The controller inputs an information signal from a wheel speed sensor, a vehicle speed sensor or the like, detects a locked state of the wheel, and outputs a control current to the pressure increasing / decreasing solenoid valves 9 and 10 for opening / closing operation.

The operation of this embodiment will be described below.

When there is a risk that the wheels may lock during sudden braking of the vehicle, a control current is output from the controller to the solenoid valves 9 and 10 for pressure increase / decrease through a drive circuit to open / close the wheel cylinders. The internal pressure of 3 is repeatedly increased, maintained, reduced, maintained, and re-increased so that the wheels maintain the optimum slip ratio. Of course, during pressure boosting control, auxiliary pressure is applied to the master cylinder 1 from the accumulator 17 of the hydraulic booster system B.

Further, during the pressure reduction control of the wheel cylinders 3, the reserve mechanisms 7 are passed from the wheel cylinders 3 through the pressure reducing solenoid valves 10, the branch passages 6a and 6b, the first check valves 11 and 12, respectively. The brake fluid pressures flowing into the storage chambers 23, 23 of the fuel cells 8 and 8 are returned to the main passage 5 by the high fluid pressure of the accumulator 17. That is, at the initial stage of the pressure reducing control, the switching solenoid valves 28, 29 are de-energized by the controller, and the hydraulic chambers 24, 24 are in communication with the return passages 27, 27. Therefore, the brake fluid pressure that has flowed into the storage chambers 23, 23 pushes the pistons 22, 22 downward against the spring force of the compression coil springs 25, 25, so that the volume of the storage chambers 23, 23 temporarily increases. Will be stored in the store. Then, when the switching solenoid valves 28 and 29 are alternately energized and the first switching solenoid valve 28 is energized first, the return passage 27 is closed and the supply passage 26 is opened, so that the accumulator 17 is opened. Of high hydraulic pressure is supplied into the hydraulic chamber 24 through the supply passage 26. Therefore, the high hydraulic pressure is applied to the second pressure receiving surface 22b of the piston 22 having a large diameter, and the piston 22 is pushed up by the combined force with the spring force of the compression coil spring 25. As a result, the brake fluid in the storage chamber 23 is discharged to the downstream portion 6c as the volume decreases, and is forcibly returned to the master cylinder 1 through the second check valve 13.

On the other hand, the second switching solenoid valve 29 is energized after the second switching solenoid valve 28 is energized to perform the same operation as described above, and the brake fluid pressure in the storage chamber 23 is changed to the second check valve 14 Is forcibly returned to the master cylinder 1 via.

Simultaneously with the energization of the second switching solenoid valve 29, the first switching solenoid valve 28 is de-energized, the supply passage 26 is closed, and the return passage 27 is opened, so that the hydraulic chamber is closed. Since the brake fluid in 24 is returned to the circulation passage 15 upstream of the pump 16, the fluid pressure chamber 24 becomes a low pressure and the piston 22 is pushed down by the brake fluid pressure flowing into the storage chamber 23, and the volume of the storage chamber 23 is reduced. To increase. When the wheel cylinder 3 is depressurized, since the main passage 5 on the master cylinder 1 side is at high pressure, the closing force of the second check valves 13 and 14 becomes strong, so that the hydraulic pressure in the wheel cylinder 3 is increased. Is supplied only to the storage chambers 23, 23 and does not flow into the master cylinder 1 side.

Then, by continuously repeating energization / de-energization for the first and second switching solenoid valves 28, 29, the volume of the storage chambers 23, 23 is increased / decreased by the pistons 22, 22, and the pumps The brake fluid in the storage chambers 23, 23 can be forcibly and efficiently returned to the master cylinder 1 by the action.

Therefore, sufficient brake fluid is always compensated in the master cylinder 1, so that even if the pipe of the return passage 27 is cracked or cut and the brake fluid leaks, the return fluid flows back to the return passage 27. Since it is separated from the passage 6 by the piston 22 of the reserve mechanisms 7 and 8, it does not affect the amount of brake fluid on the main passage 5 side, so a sufficient braking force can be secured. In particular, when the next wheel cylinder 3 is decompressed after one reserve mechanism 7 pushes the brake fluid to the master cylinder 1 side, the other reserve mechanism 8 already supplies the next brake fluid. It is in a standby state. In other words, since both reserve mechanisms 7 and 8 alternately perform pumping action, the responsiveness of the brake fluid supply to the master cylinder 1 is improved, and the increase of the reservoir capacity results in the case of one reservoir mechanism. In comparison, a sufficient amount of brake fluid is compensated for, and braking force can also be improved.

Moreover, the brake fluid in the storage chambers 23, 23 is pumped to the master cylinder 1 by the high pressure of the accumulator 17 and the pumping action of the reserve mechanisms 7, 8 using the first and second switching solenoid valves 28, 29. As a result, no special motor pump or the like is needed. As a result, the weight and size of the device can be reduced and driving noise and vibration can be reduced. In addition, manufacturing workability can be improved and cost can be reduced.

Furthermore, the forced circulation of the brake fluid from the wheel cylinder 3 to the master cylinder 1 reduces the kickback of the brake pedal 2.

The present invention is not limited to the configuration of the above-mentioned embodiment, and it is also possible to apply an accumulator or the like used in a so-called traction control system as the pressure generating means.

[0026]

[Effect of device]

 As is apparent from the above description, according to the present invention, when the wheel cylinder is depressurized during antilock control, the brake fluid pressure that has flowed into the storage chamber is generated by the pressure generation means, the switching valve and the two reserve mechanisms. Since the force is forcibly returned to the master cylinder by the action, sufficient brake fluid is constantly replenished in the master cylinder. Therefore, even if the return passage piping is cracked or cut and brake fluid leaks, the brake fluid amount between the master cylinder and the wheel cylinder is prevented from decreasing, and sufficient braking force is secured. .

In particular, according to the present invention, a reservoir mechanism is provided in each branch passage, and both reservoir mechanisms alternately perform the pumping action, so that the brake fluid supply responsiveness to the brake fluid pressure circuit on the master cylinder side is improved. In addition to the improvement, the increase in the reservoir capacity makes it possible to compensate for a sufficient amount of brake fluid as compared with the case of one reservoir mechanism, and to improve the braking force.

Moreover, since a motor pump or the like for returning the brake fluid from the storage chamber to the master cylinder is not required, the weight and size of the device can be reduced and driving noise and vibration can be reduced. In addition, manufacturing work efficiency can be improved and manufacturing cost can be reduced.

[Brief description of drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Master cylinder 3 ... Wheel cylinder 4 ... Reservoir tank 5 ... Main passage 6 ... Branch passage 7, 8 ... Reserve mechanism 11-14 ... Check valve 17 ... Accumulator (pressure generation means) 22 ... Piston 23 ... Storage chamber 24 ... Hydraulic chamber 26 ... Supply passage 27 ... Return passage 28, 29 ... First and second switching solenoid valves (switching valves)

Claims (1)

[Scope of utility model registration request] 1. A main passage for supplying a brake fluid pressure in a master cylinder equipped with a reservoir tank to a wheel cylinder of each wheel, and a brake fluid pressure in the wheel cylinder during antilock control via a reserve mechanism. In a brake fluid pressure control device for a vehicle provided with a return passage for returning to the passage, the reserve mechanism is provided in each branch passage of the return passage, and the fluid is stored by each piston sliding inside each cylinder of each reserve mechanism. While partitioning into a chamber and a hydraulic chamber, while connecting the intermediate end of each branch passage to each storage chamber, the hydraulic pressure for each piston operation is supplied to each hydraulic chamber via a supply passage. A pressure generating means to be supplied is connected, and further, the inflow of the brake fluid is allowed to the front and rear positions of the reserve mechanism of the branch passage only from the wheel cylinder in the direction of the main passage. A pair of check valves are provided in series, and a switching valve for switching between the return passage for returning the brake fluid in the hydraulic chamber to the reservoir tank and the supply passage is provided. Brake fluid pressure control device for vehicles.