JPH08109903A - Hydraulic system - Google Patents

Abstract

PURPOSE: To provide a hydraulic system to reduce bubbles to be generated when the hydraulic fluid in a reservoir is sucked by a suction pump. CONSTITUTION: A braking device having an anti-lock braking force control system is provided with circulating passages 45a, 45b to circulate the braking fluid discharged from wheel cylinders 6-9 to the supply side, reservoirs 45a, 45b to refill the braking fluid to the circulating passages 45a, 45b, and suction pumps 72, 73 to suck the braking fluid in the circulating passages 45a, 45b and discharge it to feeding passages 38a-38d. The reservoirs 4, 5 reduces the range where the cavitation is generated to the range from the reservoirs 4, 5 to the suction pumps 72, 73 by the sliding of a piston 12 to shut off the circulating passages 45a, 45b when the braking fluid in the reservoirs 4, 5 is reduced in volume below the prescribed value by the suction of the suction pumps 72, 73.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system, and more particularly to a hydraulic system configured to reduce the generation of bubbles when hydraulic fluid in a reservoir is sucked by a suction pump.

[0002]

2. Description of the Related Art A hydraulic system using a so-called self-priming pump, which sucks hydraulic oil accumulated in a reservoir provided in a reflux pipe by a pump and supplies it to an actuator through a supply pipe, has been conventionally known. There is. This hydraulic system
As shown in FIG. 6, in the suction stroke of the pump 91, since the inside of the pump 91 becomes a negative pressure, the discharge side check valve 93 provided in the supply pipeline 92 is closed and the return pipeline is closed. The suction side check valve 95 provided at 94 is opened, and the hydraulic oil downstream from the suction side check valve 95 is sucked. In the compression stroke of the pump 91, the pump 9
Since the inside of 1 has a positive pressure, the discharge side check valve 93 is opened, the suction side check valve 95 provided in the return conduit 94 is closed, and the working oil is supplied to the actuator 96.

As an application of such a hydraulic system, for example, an antilock control device described in JP-A-63-240457 can be cited. This hydraulic system collects the hydraulic oil discharged from the wheel cylinders to the supply side, a return line that stores the hydraulic oil (brake fluid) in the return path, and a hydraulic oil in the return path. It is configured to have a suction pump (also called a self-priming pump) for sucking, opening and closing the solenoid valve provided in the supply system path, and supplying hydraulic pressure from the pump to the wheel cylinder. This prevents the wheels from locking during sudden braking.

[0004]

Therefore, in the conventional hydraulic system shown in FIG. 6, the working oil accumulated in the reservoir 97 provided in the return conduit 94 is generated by the negative pressure inside the pump 91. Since the suction oil is supplied to the actuator 96 via the supply pipeline 92, the residual oil amount in the reservoir 97 is one pump (one cycle).
When the amount is less than or equal to the suction amount (when the reservoir is empty), air is sucked from the reservoir 97, or the pressure of the hydraulic oil is reduced and the gas dissolved in the hydraulic oil is separated, which causes so-called aeration. I will wake you up.

When such a state occurs, air is pushed out to the actuator 96 via the supply line in the compression stroke of the pump 91, and the operating efficiency of the actuator 96 is reduced by the elastic deformation of the air. is there. Therefore, in view of the above problems, it is an object of the present invention to reduce the generation of bubbles even when the inside of the reflux system passage has a negative pressure due to the suction operation of the suction pump.

[0006]

The invention according to claim 1 is
A supply system path for supplying the working oil to the actuator, a return system path for returning the working oil discharged from the actuator to the supply side, a reservoir for replenishing the return system path with the working oil, and a flow path in the return system path. In a hydraulic system having a suction pump that sucks hydraulic oil and discharges it to the supply system path side, the upstream side conduit and the downstream side conduit of the recirculation system path are communicated with the reservoir, and the upstream side conduit or the downstream side A communication hole communicating with either one of the side conduits is provided at a position facing the piston in the reservoir, and when the working fluid in the reservoir is reduced to a predetermined amount or less by the suction operation of the suction pump, the piston is It is characterized in that it is displaced to a position where the communication hole is closed.

The invention of claim 2 is characterized in that the actuator is a brake device having an anti-lock braking force control system.

[0008]

According to the above claim 1, when the working fluid in the reservoir is reduced to a predetermined amount or less by the suction operation of the suction pump, the piston is displaced to the position where the communication hole is closed, so that the residual oil amount in the reservoir is reduced. Does not become smaller than the suction amount of one pump, and does not suck air from the reservoir.

Further, according to the second aspect, since the actuator is the brake device having the anti-lock braking force control system, it is possible to greatly reduce the amount of bubbles generated by the cavitation in the return passage in the brake device of the automobile. It will be possible.

[0010]

1 and 2 show a brake device having an antilock braking force control system to which an embodiment of a hydraulic system according to the present invention is applied. In both figures, 1 is a brake pedal, 2 is a vacuum booster, and 3 is a brake pedal 1.
Master cylinders (actuators) that generate a brake fluid pressure in accordance with the stepping force of the brake booster and the boosting action of the vacuum booster 2, and 4 and 5 are reservoirs for replenishing the brake fluid (hydraulic oil) to a return passage described later, 6 to 9 Is a wheel cylinder of a brake mechanism that receives brake fluid pressure from the master cylinder 3 to brake each wheel.

Since the reservoirs 4 and 5 have the same configuration, only the configuration of one reservoir 4 will be described with reference to FIG. 2, and the description of the other reservoir 5 will be omitted. In FIG. 2, the reservoir 4 is a cylinder chamber 1 formed in the housing 10.
1, a piston 12 slidably provided in the cylinder chamber 11, a coil spring 13 that is inserted into the recess 12a of the piston 12 and presses the piston 12 upward, and a spring receiver 14 that abuts the lower end of the coil spring 13. , Spring receiver 14
And a ring-shaped retaining ring 15 that locks with the lower opening 11a of the cylinder chamber 11.

An inflow hole (communication hole) 16 to which the brake fluid is supplied and an outflow hole (communication hole) 17 to which the brake fluid is discharged are formed in the upper part of the cylinder chamber 11. The inflow hole 16 is located outside the center of the cylinder chamber 11.
Is provided so as to face the vicinity of the outer periphery of the outflow hole 1
7 is formed so as to coincide with the axis of the piston 12, which is the center of the cylinder chamber 11.

On the upper surface of the piston 12, the piston 1
An abutting portion 12b that abuts the upper inner wall 11a of the cylinder chamber 11 when 2 moves up. This contact portion 12b
Is provided at the center of the upper surface of the piston 12,
An escape portion 12 c facing the inflow hole 16 is provided near the outer periphery of the upper surface of the piston 12. Therefore, when the piston 12 moves upward and the abutment portion 12b abuts the upper inner wall 11b of the cylinder chamber 11, the outflow hole 17 is closed, so that the brake fluid return passage, which will be described later, is cut off. Further, since the escape portion 12c is provided on the upper surface of the contact portion 12b, the piston 12 can move upward until the contact portion 12b contacts the upper inner wall 11b. Further, the contact portion 12
b is formed into a smooth flat surface by grinding, and when it comes into contact with the upper inner wall 11b of the cylinder chamber 11, the outflow hole 1
7 can be closed in an airtight state.

In this embodiment, as will be described later, the reservoir 4
Since the piston 12 can slide in the cylinder chamber 11 according to the remaining amount of the brake fluid in the cylinder chamber 11 to open and close the outflow hole 17, the reservoir 4 serves as a shutoff valve for the return passage. Can function. for that reason,
The structure is simplified as compared with the case where a shutoff valve separate from the reservoir 4 is provided in the return passage.

On the outer circumference of the piston 12, an O-ring 18 that seals between the cylinder chamber 11 and the inner wall is mounted. The through hole 14 is provided at the center of the spring receiver 14.
Since a is bored, the bottom of the piston 12 is open to the atmosphere. Therefore, when the brake fluid in the cylinder chamber 11 decreases, the piston 12 moves upward due to the pressing force of the coil spring 13 and discharges the brake fluid from the outflow hole 17 to the return passage. Further, the brake fluid pressure due to the spring force of the coil spring 13 becomes the minimum wheel cylinder pressure in the wheel cylinders 6-9.

Therefore, the minimum wheel cylinder pressure applied by the piston 12 of the reservoir 4 becomes the limit pressure for unlocking the tire when traveling on a low μ road. The limit pressure can be maintained at atmospheric pressure by setting the spring force of the coil spring 13 to such a degree that only the weight of the piston 12 is supported. It returns to FIG. 1 again and demonstrates.

In FIG. 1, the brake fluid pressure generated from the master cylinder 3 when the brake pedal 1 is depressed is
It is connected to the wheel cylinders 6 to 9 via the second brake pipe lines 20 and 21. Numerals 22 to 25 are hydraulic pressure switching valves for increasing pressure, which are normally open 2-port 2-position spring offset solenoid valves, and are normally opened to supply the brake hydraulic pressure from the master cylinder 3 to the wheel cylinders 6 to 9. However, the valve is closed immediately before the wheels are locked, and the brake fluid pressure supply from the master cylinder 3 is stopped.

Numerals 26 to 29 are pressure-reducing hydraulic pressure switching valves which are normally closed two-port two-position spring offset solenoid valves, and are normally closed to hold the brake hydraulic pressure to each wheel cylinder 6-9. The valve is opened immediately before the wheels are locked, and the brake fluid pressure to each wheel cylinder 6-9 is released to the reservoirs 4 and 5 to reduce the brake fluid pressure.

Supply pipelines 30 to 33 connected to the first and second brake pipelines 20 and 21, and the supply pipeline 3 at one end.
The supply pipes 34 to 37, which are in communication with 0 to 33 and the other end of which is in communication with the wheel cylinders 6 to 9, form supply system passages 38a to 38d for the wheel cylinders 6 to 9, respectively.
In addition, return lines 39 to 42, one end of which communicates with the hydraulic pressure switching valves 26 to 29 and the other end of which communicates with the reservoirs 4 and 5, and the reservoirs 4 and 5 to the first and second brake lines 20 and 21. The recirculation pipe lines 43 and 44 extending so as to be connected to the recirculation line form recirculation system lines 45a and 45b. Recirculation pipe 39-
42 is connected to the inflow holes 16 of the reservoirs 4 and 5, and the return pipe lines 43 and 44 are connected to the outflow holes 17 of the reservoirs 4 and 5.

Therefore, the brake fluid in the recirculation pipe lines 39 to 42 passes through the inflow hole 16 and flows into the cylinder chamber 11 by the suction operation of the suction pumps 72 and 73, which will be described later, and flows out from the outflow hole 17 into the recirculation pipe. It is sucked into the paths 43 and 44 and is returned to the supply side. In the pipe lines 30 to 33 on the supply side, throttles 46 to 49 for restricting the amount of brake fluid supplied to the pressure increasing hydraulic pressure switching valves 22 to 25, throttles 46 to 49 and pressure increasing hydraulic pressure switching valves 22 to 25 are provided. Bypass lines 50 to 53 for bypassing,
Each wheel cylinder 6 via the bypass lines 50 to 53
Check valves 54 to 57 for allowing the brake fluid on the 9th to 9th sides to return to the master cylinder 3 side and preventing the brake fluid from flowing from the master cylinder 3 side to the wheel cylinders 6 to 9 sides. Has been done.

Further, the wheel cylinders 6 and 9 for the rear wheels
Proportioning valves 58 and 59 that control the brake fluid pressure to the rear wheels are arranged in the supply pipes 34 and 37 that communicate with each other so as to prevent the rear wheels from locking during braking. Further, throttles 60 to 63 for restricting the amount of brake fluid recirculated from each wheel cylinder 6 to 9 to a predetermined amount are provided in the recirculation pipe lines 39 to 42 downstream of the depressurization hydraulic pressure switching valves 26 to 29. ing.

Suction pump units 64 and 65 for sucking the brake fluid in the reservoirs 4 and 5 to recirculate the fluid to the master cylinder 3 side into the respective return pipe lines 43 and 44, and a filter 6
6, 67, throttles 68, 69 for reducing the flow rate of the brake fluid to be returned to the master cylinder 3 side, allowing the brake fluid to return to the master cylinder 3 side, and the brake fluid from the master cylinder 3 side to the suction pump unit 64. , 6
Check valves 70 and 71 for preventing the flow to the valve 5.

The suction pump units 64 and 65 are respectively suction pumps 72 and 73, check valves 74 and 75 arranged upstream of the suction pumps 72 and 73, and suction pumps 72 and 7.
The check valves 76 and 77 are disposed downstream of the check valve 3. The suction pumps 72, 73 are provided at positions close to the reservoirs 4, 5 described above, and the distance from the suction pumps 72, 73 to the outflow holes 17 of the reservoirs 4, 5 is set to be relatively small.

The suction pumps 72 and 73 are constantly pump motor 78 while anti-lock braking force control is being executed.
Driven by Then, the suction pumps 72 and 73 become the suction process when the pump plunger (not shown) moves downward, and the discharge process when the pump plunger (not shown) moves upward. In the suction process, the suction pumps 72, 7 are used.
3 is provided upstream of the check valves 74 and 75 and is opened downstream of the suction pumps 72 and 73.
6,77 close. Then, in the discharge step, the check valves 74 and 75 are arranged upstream of the suction pumps 72 and 73 and closed, and the check valves 76 and 77 arranged downstream of the suction pumps 72 and 73 are opened. .

In this way, the suction pumps 72, 73 are selected depending on the operating direction of the pump plungers of the suction pumps 72, 73.
The brake fluid is returned to the master cylinder 3 by opening and closing the check valves 74, 75 and the check valves 76, 77 disposed upstream and downstream of the above. In the brake device having the antilock braking force control system configured as described above, when the brake pedal 1 is depressed, the master cylinder 3 increases the brake fluid pressure to enter the pressure increasing mode. In the pressure increasing mode, the pressure increasing hydraulic pressure switching valves 22 to 25 are held in the open state and the pressure reducing hydraulic pressure switching valves 26 to 29 are held in the closed state. Therefore, the increased brake fluid pressure is supplied to the wheel cylinders 6 to 9 via the first and second brake conduits 20 and 21, the supply conduits 30 to 33, and the supply conduits 34 to 37. , Each wheel is braked.

Then, for example, when the vehicle is running on a low μ road and is braked until just before the wheels are locked, the anti-lock braking force control system switches to the pressure reducing mode or the holding mode. In this pressure reducing mode, the pressure increasing hydraulic pressure switching valves 22 to 25 corresponding to the wheels immediately before locking are switched to the closed state, and the pressure reducing hydraulic pressure switching valves 26 to 29 are switched to the open state. As a result, the brake fluid pressure in the wheel cylinders 6 to 9 escapes to the reservoirs 4 and 5 via the recirculation pipe lines 39 to 42, so that the braking force on the wheels is released and the wheels are prevented from locking.

In the holding mode, the pressure increasing hydraulic pressure switching valve 2
2 to 25 and the pressure-reducing fluid pressure switching valves 26 to 29 are kept closed, and the brake fluid pressure in the wheel cylinders 6 to 9 is retained. During such an anti-lock braking operation, the pump motor 78 is always activated to prevent the master cylinder 3 from running out of brake fluid. Therefore, when the pressure reducing mode is set during the antilock braking operation and the pressure reducing hydraulic pressure switching valves 26 to 29 are opened, the wheel cylinders 6 to
The brake fluid from the 9 side flows out to the return pipe lines 39 to 42. Then, the brake fluid in the return pipe lines 39 to 42 flows into the cylinder chamber 11 through the inflow holes 16 of the reservoirs 4 and 5 by the suction operation of the suction pumps 72 and 73 driven by the pump motor 78. Further, it is sucked into the return conduits 43, 44 from the outflow holes 17 of the reservoirs 4, 5.

After that, the brake fluid sucked by the suction pumps 72, 73 is filtered by the filters 66, 67 and the throttles 68, 6.
9. After passing through the check valves 70 and 71, they are returned to the first and second brake pipes 20 and 21. However, during the anti-lock braking operation, for example, when the rotational speed of each wheel becomes high, the pressure reducing mode is switched to the pressure increasing mode or the holding mode, and the pressure reducing hydraulic pressure switching valves 26 to 29 are closed and the pressure increasing hydraulic pressure is increased. The switching valves 22 to 25 are opened.

When the pressure reducing mode is changed to the pressure increasing mode or the holding mode in this way, the brake fluid continues to be circulated to the master cylinder 3 side by the suction operation of the suction pumps 72 and 73, so that the cylinder chambers 11 of the reservoirs 4 and 5 are The brake fluid filled in
4 is sucked. Therefore, the brake fluid in the cylinder chamber 11 gradually decreases, and the piston 12 moves upward accordingly. Further, when the brake fluid is sucked by the suction operation of the suction pumps 72, 73, the piston 12 contacts the upper inner wall 11b as shown in FIG. Since the contact portion 12b projects in the center of the upper surface of the piston 12, when the brake fluid in the cylinder chamber 11 is sucked, the contact portion 12b contacts the upper inner wall 11b and closes the outflow hole 17.

As a result, the return passages 45a and 45b are
It is shut off by the piston 12 of the reservoirs 4, 5. As a result, during the antilock braking operation, the pressure reducing mode is switched to the pressure increasing mode or the holding mode, and the pressure reducing hydraulic pressure switching valve 26
Even if ~ 29 is closed, the return line 3 upstream of the inflow hole 16
9 to 42, cavitation is prevented from generating bubbles, and the distance from the suction pumps 72, 73 to the outflow holes 17 of the reservoirs 4, 5 is set to be relatively small. The amount of bubbles generated by cavitation between the outflow hole 17 and the suction pumps 72, 73 is considerably reduced.

Therefore, the amount of bubbles generated during the anti-lock braking operation is suppressed to a small amount, and the bubbles generated by cavitation are prevented from being discharged to the master cylinder 3 side. Further, when the brake fluid in the reservoirs 4 and 5 is sucked by the suction operation of the suction pumps 72 and 73 as described above, the piston 12 closes the outflow hole 17 and the reflux system passage 45.
Since a and 45b are shut off, the residual oil amount in the reservoirs 4 and 5 does not become smaller than the suction amount of the suction pumps 72 and 73 once, and air is not sucked from the reservoirs 4 and 5.

In the above embodiment, the outflow hole 17 is closed when the pistons 12 of the reservoirs 4 and 5 move upward, but the invention is not limited to this, and the outflow hole 17 is deviated from the center of the cylinder chamber 11. The piston 12 may be opened and closed by facing the outer periphery of the piston 12, and the inflow hole 16 may be opened and closed so as to be aligned with the axis of the piston 12 that is the center of the cylinder chamber 11. Of course it's good.

FIG. 4 shows a modification of the present invention. In the figure, an annular groove 12d is formed on the upper surface of the contact portion 12b of the piston 12 so as to surround the outflow hole 17.
An O-ring 81 is inserted in 2d. Therefore, during the anti-lock braking operation, the pressure reducing mode is switched to the pressure increasing mode or the holding mode, and the pressure reducing hydraulic pressure switching valves 26-2 are provided.
When the valve 9 is closed, the brake fluid in the reservoirs 4 and 5 is sucked by the suction operation of the suction pumps 72 and 73, and the piston 12 of the reservoirs 4 and 5 moves upward.

As a result, the contact portion 12b of the piston 12 is
Immediately before the abutting against the upper inner wall 11b of the cylinder chamber 11.
The ring 81 abuts the upper inner wall 11b to seal the periphery of the outflow hole 17. Therefore, the space between the inflow hole 16 and the outflow hole 17 is liquid-tightly sealed by the O-ring 81.
It is prevented that cavitation occurs and bubbles are generated in the upstream return conduits 39 to 42. As a result, the bubbles sucked by the suction pumps 72 and 73 are significantly reduced.

FIG. 5 shows another modification of the present invention. In the figure, an annular groove 11c is formed so as to surround the outflow hole 17 in the upper inner wall 11b with which the abutting portion 12b of the piston 12 abuts, and an O-ring 82 is inserted into this annular groove 11c. . Therefore, when the pressure reducing mode is switched to the pressure increasing mode or the holding mode during the anti-lock braking operation and the pressure reducing fluid pressure switching valves 26 to 29 are closed, the suction operation of the suction pumps 72 and 73 causes the reservoirs 4 and 5 to move. The brake fluid therein is sucked and the pistons 12 of the reservoirs 4 and 5 move upward.

As a result, the contact portion 12b of the piston 12 is
Immediately before the abutting against the upper inner wall 11b of the cylinder chamber 11.
The ring 82 abuts the upper surface wall 11b of the abutting portion 12b to seal the periphery of the outflow hole 17. Therefore, a space between the inflow hole 16 and the outflow hole 17 is liquid-tightly sealed by the O-ring 82, and cavitation is prevented from occurring in the return conduits 39 to 42 upstream of the inflow hole 16 to generate bubbles. .
As a result, the bubbles sucked by the suction pumps 72 and 73 are significantly reduced.

In the above embodiment, the brake device having the anti-lock braking force control system of the automobile has been described as an example, but the present invention is not limited to this and can be applied to the hydraulic system of other devices.

[0038]

As described above, according to claim 1 of the present invention, when the working fluid in the reservoir is reduced to a predetermined amount or less by the suction operation of the suction pump, the piston is displaced to the position where the communication hole is closed. Therefore, the amount of residual oil in the reservoir is
It does not become less than the suction amount of one time, and does not suck air from the reservoir. Moreover, the range in which cavitation occurs can be reduced to a short circulation path from the reservoir to the suction pump, and thus the amount of bubbles generated by cavitation can be greatly reduced. Therefore, even if the suction operation of the suction pump is continued, the amount of bubbles sucked by the suction pump and discharged to the supply side can be significantly reduced.

Further, according to the second aspect, since the actuator is the brake device having the anti-lock braking force control system, even if the pressure reducing mode is switched to the pressure increasing mode or the holding mode, the return path in the brake device is changed. The amount of bubbles generated by cavitation can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a brake device having an antilock braking force control system to which an embodiment of a hydraulic system according to the present invention is applied.

FIG. 2 is a vertical cross-sectional view showing the structure of a reservoir.

FIG. 3 is a vertical sectional view showing a piston operation of the reservoir.

FIG. 4 is a vertical cross-sectional view of a modified example of the present invention.

FIG. 5 is a vertical cross-sectional view of another modification of the present invention.

FIG. 6 is a configuration diagram of a hydraulic circuit showing an example of a conventional hydraulic system.

[Explanation of symbols]

 1 Brake Pedal 3 Master Cylinder 4, 5 Reservoir 6-9 Wheel Cylinder 10 Housing 11 Cylinder Chamber 12 Piston 13 Coil Spring 16 Inflow Hole 17 Outflow Hole 20 First Brake Pipeline 21 Second Brake Pipeline 22-25 Liquid Pressure Switching for Pressure Boosting Valves 26 to 29 Liquid pressure switching valve for decompression 38a to 38d Supply line 39 to 44 Reflux line 45a, 45b Reflux line 72,73 Suction pump 78 Pump motor

Claims (2)

[Claims] 1. A supply system path for supplying hydraulic oil to an actuator, a return system path for returning the hydraulic oil discharged from the actuator to a supply side, and a reservoir for replenishing the return system path with hydraulic oil, In a hydraulic system having a suction pump that sucks hydraulic oil in the reflux system passage and discharges it to the supply system passage side, the upstream side conduit and the downstream side conduit of the reflux system passage are communicated with the reservoir, and the upstream side A communication hole communicating with either the side pipeline or the downstream pipeline is provided at a position facing the piston in the reservoir, and the working fluid in the reservoir is reduced to a predetermined amount or less by the suction operation of the suction pump. At this time, the piston is displaced to a position that closes the communication hole. 2. The hydraulic system according to claim 1, wherein the actuator is a brake device having an antilock braking force control system.