JPS62181953A - Hydraulic braking device for automobile - Google Patents

Abstract

PURPOSE:To make the extent of driving capacity smaller without imposing high hydraulic pressure at the time of starting a pump as well as to reduce weight and cost either, by constituting a device so as to comprise a buffer of lower pressure than an accumulator at the nearer pump side than a check valve in a pump passage, and a hydraulic pressure difference generating device and a pilot type on-off valve operating with the hydraulic pressure between this buffer and the pump. CONSTITUTION:This device is constituted so as to comprise a buffer 78 being lower pressure than an accumulator 68 at the nearer side of a pump 70 than a check valve 74 in a pump passage 72, and an orifice 88, a reflux passage 82 connecting this buffer 78 to a reservoir 64, a pilot type on-off valve 84 operating with a hydraulic pressure difference in the orifice 88 in the reflux passage 82 between the buffer 78 and the pump 70. If so, the hydraulic pressure difference is produced in the orifice 88 with the pump 70 started, whereby the pilot type on-off valve 84 is selected, cutting off the reflux passage 82. In this case, however, a discharge fluid flows into the buffer 78 at low pressure, whereby there is unnecessary to drive the pump against high hydraulic pressure from the outset of starting. Therefore, a pump motor 102 can be formed into small size little in capacity, and weight and cost both are reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic brake system for automobiles, and particularly to a brake system equipped with a hydraulic pressure source including a pump, an accumulator, etc. to control the operation of the brake. It is about improvement.

Some of the conventional hydraulic brake devices for automobiles include, for example,
There is one equipped with a hydraulic booster as described in Japanese Patent No. 9-50848. This hydraulic booster is installed between an operating member such as a brake pedal and a mask cylinder that generates brake fluid pressure in response to the operation of the operating member, and boosts the operating force applied to the operating member to increase the pressure in the mask cylinder. and requires a hydraulic pressure source for operation. In the brake device of the above publication,
This hydraulic pressure source includes a pump and an accumulator. In this way, a relatively small pump can pump up liquid and store it at high pressure in the accumulator, and a sufficient amount of high-pressure liquid can be supplied to the booster as needed.

Problems to be Solved by the Invention As described above, in a liquid pressure source that includes an accumulator and a pump, when the liquid pressure in the accumulator drops to the lower limit, the pump is activated and starts replenishing liquid, and the liquid in the accumulator is The pump is stopped when the hydraulic pressure reaches the upper limit, but even the lower limit must be high enough to activate the booster.
For example, it is set to a high value such as 140 kg/crA. Therefore, it is necessary for the pump to push the liquid into the accumulator against this high hydraulic pressure from the time of startup. Since both the inertial load and the inertial load are applied redundantly, a problem arises in that the pump drive device inevitably becomes large and expensive.

Further, a DC electric motor is often used as a pump drive device, but in this case, the starting current is extremely large, the brushes are heavily worn out, and the life of the motor is shortened. Furthermore, if the pump is a plunging pump, the pump will stop near the bottom dead center of the plunger, and the motor rotor will also stop at an approximately fixed rotational phase, resulting in the commutator and brushes Since the motor is started from a state in which the commutator and the commutator are always in the same relative positional relationship, a problem arises in that the durability of the commutator is reduced.

In addition, as a pump drive device, it is also possible to use a device that includes a drive source provided for a specific purpose, such as an engine for driving a car, and a clutch that connects or disconnects the drive source and the pump. If the load at startup is large, a clutch with a large capacity is required, and there is also the problem that the load fluctuations of the engine or other drive source become large.

The above was explained using the hydraulic pressure source of a hydraulic booster as an example.
Hydraulic brake systems include an anti-lock device that prevents the wheels from slipping against the road surface because the brake's rotational restraining force on the wheels is excessive in relation to the friction coefficient of the road surface, and anti-lock devices that prevent the wheels from slipping against the road surface when the vehicle starts or Traction control devices are sometimes installed to prevent the drive wheels from slipping against the road surface due to excessive drive force during acceleration, and these hydraulic pressure sources include pumps and accumulators. A similar problem occurs when used.

With the above circumstances as a background, the present invention has been proposed to provide a brake that is operated by a hydraulic cylinder to suppress the rotation of a wheel, a normally closed control valve that controls the hydraulic pressure of the hydraulic cylinder, and a brake that is connected to the control valve. An accumulator, a pump that supplies the liquid pumped from the reservoir to the accumulator through a pump passage including a check valve, and the hydraulic pressure of the accumulator is maintained within a predetermined range by controlling the start and stop of the pump. A hydraulic brake device for an automobile including a pump control means, wherein a high load based on hydraulic pressure is not applied to the pump drive device when the pump is started, and is applied only after the operating speed of the pump reaches a steady state. This was done for the purpose of obtaining a pump drive device that is equipped with protection means for protecting the pump drive device.

Means for Solving the Problems Therefore, the hydraulic brake device for an automobile according to the present invention has the following features:
(a) a buffer connected to a portion of the pump passage closer to the pump than the check valve and storing liquid at a lower pressure than the aqueemulator; , a liquid pressure difference generating means for generating a liquid pressure difference in the liquid flowing through the pump passage; (d) a reflux path connecting the Cl buffer to the reservoir; The reflux passage is connected to the pilot passage and the second pilot passage on the downstream side, and the reflux passage is always kept in communication, but if a fluid pressure difference occurs between the first pilot passage and the second pilot passage, the reflux passage is connected to the downstream side by a second pilot passage. and a pilot-operated on-off valve that can be switched to a state where it shuts off.

Function: In the automobile hydraulic brake system constructed as described above, while the pump is stopped, the biloft type on-off valve maintains the reflux path in a communicating state, and no liquid is stored in the buffer. Then, when it is necessary to supply liquid to the Akiemulator and the pump is started, a hydraulic pressure difference is generated by the hydraulic pressure difference generating means, and the pilot type on-off valve is switched by the hydraulic pressure difference to shut off the reflux path. However, since the discharged liquid can flow into the buffer at low pressure, the pump does not have to push liquid into the accumulator against high liquid pressure from the beginning of startup, and the pump drive device has an inertial load of the pump and the pump drive device itself. There is no load based on hydraulic pressure.

Then, after the pump reaches steady operating speed, the buffer reaches saturation and no liquid can enter, so the discharged liquid can no longer flow out of the pump passage against the high liquid pressure in the accumulator. Flows into the accumulator.

In addition, when the hydraulic pressure in the accumulator reaches the upper limit hydraulic pressure, the pump control means stops the pump, so the hydraulic pressure difference on both sides of the hydraulic pressure difference generating means disappears, and the pilot-operated on-off valve returns to its original state, causing reflux. The channel is brought into communication, and the liquid stored in the buffer is discharged to the reservoir via the reflux channel.
Cycle fluid replenishment completes.

Effects As mentioned above, since the pump does not need to discharge liquid against the high hydraulic pressure of the accumulator when starting up, the pump drive device can be made smaller with less driving capacity than conventional ones, reducing weight and cost. The effect of reducing this can be obtained.

In addition, when using a DC electric motor as a pump drive device, the starting current is low, reducing brush wear, improving commutator durability, and extending the life of the motor. Furthermore, when a drive source provided for another purpose is used to drive the pump, the effect of reducing the load fluctuation caused by the activation of the pump of the drive source can be obtained.

Embodiments Hereinafter, embodiments in which the present invention is applied to a hydraulic brake device equipped with a hydraulic booster will be described with reference to the drawings.

In FIG. 1, IO is a brake pedal, which is connected to a mask cylinder 14 via a booster 12.

The mask cylinder 14 is of a tandem type that includes two pressurizing pistons in series and generates equal liquid pressure in two mutually independent pressurizing chambers, and the liquid pressure generated in each pressurizing chamber is passed through a liquid passage. 16.18 to the front wheel cylinder 20 and rear wheel cylinder 22. These wheel cylinders 20°2
Reference numeral 2 denotes hydraulic cylinders that actuate the brakes, and the actuated brakes suppress the rotation of the wheels, thereby slowing down or stopping the vehicle.

As shown in FIG. 2, the booster 12 includes a housing 24 and a power piston 26. The housing 24 is integrally connected at one end to the housing 28 of the mask cylinder 14, and has a power piston 26 disposed therein.
are fitted in a fluid-tight and slidable manner. A cylindrical partition member 3 is provided in the housing 28 of the mask cylinder 14.
0 is fixed, and the protrusion 34 of the pressure piston 32 passes through the partition member 30 in a fluid-tight and slidable manner, and can come into contact with the power piston 26 at the tip.

An input piston 36 is fluid-tightly and slidably fitted into the opposite end of the housing 24, and a power pressure chamber 38 is formed between the input piston 36, the power piston 26, and the housing 24. There is. input piston 36
A valve 4o is fixed concentrically to the power piston 26.
The valve hole is slidably and substantially liquid-tightly fitted into the valve hole formed in the valve hole. A spring 42 is disposed between the valve element 40 and the power piston 26 and urges the input piston 36 in the backward direction, and the limit of the backward movement is defined by a retaining ring 44 . Therefore, the valve 40 is always in the state shown, and the power pressure chamber 38 is connected to the liquid passage 46 formed in the valve 40. Boat 48 formed on power piston 26
．． The liquid passage 49° is connected to the low pressure boat 52 via the low pressure chamber 50, but when the liquid passage 49 is moved forward a certain distance with respect to the power piston 26, the liquid passage 46 and the boat 48
When the valve 40 is further advanced a certain distance, the liquid passage 46 is communicated with the high pressure boat 58 via a boat 54 formed in the power piston 26 and an annular chamber 56. . That is, Benko 4
0 constitutes a booster valve 60 that can be switched between communicating the power pressure chamber 38 with the power piston 26 to the low pressure boat 52, communicating it to the high pressure boat 58, and not communicating it to any boat. There is.

The low pressure boat 52 of the booster 12 is connected to a reservoir 64 by a liquid passage 62, as shown in FIG.
It is connected to the. A pump 70 is connected to the accumulator 68 through a pump passage 72, and the pump passage 72 is provided with a check valve 74. 75 and 76 are a discharge valve and a suction valve of the pump 70, respectively, and 77 is a relief valve.

A buffer 78 is connected to a portion of the pump passage 72 closer to the pump 70 than the check valve 74 . The buffer 78 has a piston 80 fluid-tightly fitted into a housing 79 and is biased in one direction by a spring 81, and has a much lower fluid pressure than the accumulator 68 (for example, 5 kg/ca).
l) to store a certain amount of liquid. This buffer 78 is connected to the reservoir 64 by a reflux path 82, and a pilot type on-off valve 84 is provided in this reflux path 82. Also, the buffer 78 of the pump passage 72
A pressure reducing valve 86 is provided between the part where the reflux path 82 is connected and the pump 70 to reduce the pressure by about 5 to 10 kg/ant.
An orifice 88 serving as a throttle means is provided in parallel to the pressure reducing valve 86. The flow path area of this orifice 88 is extremely small, and the pump 7
Most of the discharged liquid of 0 flows through the pressure reducing valve 86. The hydraulic pressure in the part of the pump passage 72 upstream of the pressure reducing valve 86, that is, on the side of the pump 70, is the first pilot passage 9.
0 to the pilot type on-off valve 84, and acts in a direction to close the pilot type on-off valve. On the other hand, the hydraulic pressure on the downstream side of the pressure reducing valve 86 is guided to the pilot type on-off valve 84 by the second pilot passage 92,
This is made to act in the direction of opening.

Further, the pilot type on-off valve 84 is always kept open by a spring 94.

The accumulator 68 is provided with a hydraulic pressure control switch 96 and an alarm switch 98, each of which is connected to a control device 100. The hydraulic pressure control switch 96 sets the upper limit hydraulic pressure of the accumulator 68 (for example, 200
kg/cn and lower limit fluid pressure (e.g. 140kg/cJ)
The control device 100 operates in accordance with the above and supplies a detection signal to the control device 100, and the control device 100 controls the pump motor 102 that drives the pump 70 based on the detection signal. On the other hand, the alarm switch 98 detects when the hydraulic pressure of the accumulator 68 drops abnormally and supplies a detection signal to the control device 100.
The control device 100 turns on the alarm lamp 1 based on this detection signal.
04 is turned on to notify the driver of an abnormal drop in hydraulic pressure.

Next, the operation will be explained.

The booster 12 is in the state shown in FIG. 2 when the brake pedal 10 is not depressed, and the booster valve 60 communicates the power pressure chamber 38 with the reservoir 64 via the low pressure port 52. When the brake pedal 10 is depressed from this state, the booster valve 60 is switched to a state in which the power pressure chamber 38 is isolated from the reservoir 64 and communicated with the accumulator 68 via the high pressure port 58. Therefore, high pressure liquid is supplied from the accumulator 68 to the power pressure chamber 38, and this liquid causes the power piston 26 to
is advanced, and the pressurizing piston 3 of the mask cylinder 14
Advance 2. As a result, brake fluid flows from the two pressurized chambers of the mask cylinder 14 to the front wheel cylinder 2.
0 and the rear wheel cylinder 22 to operate the brake. Even if the brake pedal 10 is depressed to a certain position and stopped, the power piston 26 continues to move forward, so the booster valve 60 eventually becomes in a state where the power pressure chamber 38 is not communicated with either the accumulator 68 or the reservoir 64, and the power is stopped. The piston 26 is stopped and the hydraulic pressure in the wheel cylinders 20 and 22 is kept constant.

As the brake pedal 10 is depressed, the mask cylinder 1
The reaction force applied to the pressure piston 32 due to the liquid pressure generated in the pressure chamber 4 is transmitted to the power piston 26, thereby increasing the liquid pressure in the power pressure chamber 38. This hydraulic pressure applies a reaction force to the input piston 36, allowing the driver to sense the degree of braking effectiveness using the brake pedal 10. Further, the pedal force applied to the brake pedal 10 is multiplied by the ratio of the pressure receiving areas of the input piston 36 and the power piston 26 and is transmitted to the mask cylinder 14.

When the brake pedal 10 is released, the booster valve 60 switches to communicate the power pressure chamber 38 with the reservoir 64 via the low pressure port 52, and the fluid in the power pressure chamber 38 flows back to the reservoir 64. Along with this, the power piston 26.degree. pressurizing piston 32, etc. move backward, the hydraulic pressure in the wheel cylinder 20.22 decreases, and the brake is released.

As is clear from the above explanation, each time the brake is operated, the fluid in the accumulator 68 is
8 and from there to the reservoir 64, the amount of fluid in the accumulator 68 decreases with each brake application. As a result, when the hydraulic pressure in the accumulator 68 drops to the lower limit hydraulic pressure, the hydraulic pressure control switch 96 detects this, and the control device 100 starts the pump motor 102 based on the detection signal.

When liquid is discharged from the pump 70, liquid pressure is generated upstream of the pressure reducing valve 86, and this liquid pressure is led to the pilot type on-off valve 84 through the first pilot passage 90 and switches it to the closed state. The liquid will flow into buffer 78. Since this buffer 78 is capable of containing liquid at an extremely low hydraulic pressure, the pump motor 102 is hardly subjected to any load based on the hydraulic pressure, and is mainly subjected to only the inertial load of the pump 70 and the pump motor 102 themselves. .

When the buffer 78 becomes saturated, the discharged liquid can no longer flow into the buffer 78 and flows into the accumulator 68 against the liquid pressure. However, at this point, the pump 70 has already reached a steady operating speed, and no inertial load acts on the pump motor 102, but only a load based on hydraulic pressure acts on the pump motor 102.

In this way, in the device of this embodiment, since the inertial load and the load based on hydraulic pressure are not applied to the pump motor 102 in duplicate, the pump motor 102 can be small and have a long life. .

When the hydraulic pressure in the Akiemulator 68 reaches the upper limit hydraulic pressure, the hydraulic pressure control switch 96 detects this, and the control device 100 stops the pump motor 102 based on the detection signal. As a result, there is no flow of liquid in the pump passage 72, and the orifice 88 eliminates the liquid pressure difference on both sides of the pressure reducing valve 86. Therefore, the pilot type on-off valve 84
is returned to the open state by the elastic force of the spring 94, the communication path 82 becomes in communication, and the liquid stored in the buffer 78 flows back to the reservoir 64.

Note that in order for the pilot type on-off valve 84 that was in the closed state to return to the open state, liquid flows out from the boat on the side connected to the first pilot passage 90, and the liquid flows out from the boat on the side connected to the first pilot passage 90.
Although it is necessary for the liquid to flow into the boat on the side to which the orifice 2 is connected, this flow is also allowed by the orifice 2-1 and the s88.

As is clear from the above explanation, in this embodiment, the booster valve 60 constitutes a normally closed control valve that controls the hydraulic pressure of the front wheel cylinder 20 and the rear wheel cylinder 22, which are hydraulic cylinders that operate the brakes. , hydraulic pressure control switch 96 and control device 100
constitutes the pump control means. Further, the pressure reducing valve 86 and the orifice 88 as a restricting means constitute a hydraulic pressure difference generating means that generates a hydraulic pressure difference in the pump passage when the pump is in operation, and eliminates the hydraulic pressure difference when the pump is stopped.

In this way, when a pressure reducing valve is used to generate a hydraulic pressure difference in the pump passage 72, it is possible to accurately generate a desired hydraulic pressure difference, but as shown in FIG. Even if the orifice 110 is provided, it is still possible to switch the pilot type on-off valve 84, and in this case, the orifice 110 constitutes a hydraulic pressure difference generating means.

Although two embodiments have been described above, the present invention may be modified in various ways based on the knowledge of those skilled in the art.

It can be implemented in a modified manner.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a hydraulic brake system for an automobile, which is an embodiment of the present invention, and FIG. 2 is a front sectional view showing details of the booster shown in FIG. 1. FIG. 3 is a system diagram showing the main parts of another embodiment of the present invention. 12: Booster 14: Mask cylinder 20: Front wheel cylinder 22: Rear wheel cylinder 60: Booster valve 64: Reservoir 68: Accumulator 7o: Bump 72: Pump passage 74: Check valve 78: Buffer 82: Return path 84: Pyroft type Opening/closing valve 86: Pressure reducing valve 88 Niorifice 90: First pilot passage 92: Second pilot passage 94 Nispring 96: ? & Pressure control switch 100: Control device 1o2: Pump motor 110 Niorifice

Claims (3)

[Claims] (1) A brake that is operated by a hydraulic cylinder to suppress the rotation of the wheels, a normally closed control valve that controls the hydraulic pressure of the hydraulic cylinder, an accumulator connected to the control valve, and a reservoir in the accumulator. An automobile comprising: a pump that supplies liquid pumped from the accumulator through a pump passage including a check valve; and pump control means that maintains the hydraulic pressure of the accumulator within a predetermined range by controlling starting and stopping of the pump. A hydraulic brake device for use in a hydraulic brake device, comprising: a buffer connected to a portion of the pump passage closer to the pump than the check valve and storing liquid at a lower pressure than the accumulator; and a buffer in the pump passage between the buffer and the pump. a fluid pressure difference generating means provided in the pump passageway to generate a fluid pressure difference in the liquid flowing through the pump passage; a reflux path connecting the buffer to the reservoir; They are connected by the first pilot passage and the second pilot passage on the downstream side, and the reflux passage is always kept in communication, but if a difference in fluid pressure occurs between the first pilot passage and the second pilot passage, A hydraulic brake device for an automobile, comprising a pilot-operated on-off valve that can be switched to a state where a recirculation path is cut off. (2) The hydraulic pressure difference generating means includes a pressure reducing valve provided in the pump passage and a second throttle means connected in parallel to the pressure reducing valve. Hydraulic brake equipment for automobiles. (3) The hydraulic brake device for an automobile according to claim 1, wherein the hydraulic pressure difference generating means is a second throttle means provided in the pump passage.