JPH0420822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a master brake cylinder, a power booster connected upstream of the master brake cylinder, a pressure fluid pump having a controllable electric motor, and a pressure accumulator connected to the outlet of the pump. The present invention relates to a fluid pressure brake system for an automobile comprising:

A hydraulic brake system of the above-mentioned type is described in the magazine "Botshu Technical Report", Volume 7 (1980), No.
2, page 87. In this known brake system, the pressure supply to the wheel brake cylinders of a motor vehicle takes place using a tandem master cylinder, which can be actuated by a vacuum brake booster. The first operating chamber of the tandem master cylinder is connected to a wheel brake cylinder provided on a rear wheel axle of an automobile via a normally open electromagnetic valve. Further, the second operating chamber of the tandem master cylinder is connected to a wheel brake cylinder provided on the front wheel axle of the automobile via a normally open electromagnetic valve, and is connected to the other wheel brake cylinder provided on the front wheel axle. It is connected to the cylinder via a third solenoid valve. These solenoid valves are normally open and can be switched to the other two positions by operation of the slip control electronics. When these solenoid valves are switched to an intermediate position, the connection between each wheel brake cylinder and the working chamber is interrupted. When the solenoid valve is then switched to the third position, each wheel brake cylinder is connected to the low pressure reservoir and pressurized fluid is removed from each brake cylinder, thereby reducing the effective brake cylinder pressure.

Known braking systems are also equipped with an electrically driven pressure fluid pump to re-increase the braking pressure, which pump is activated when a wheel or wheels reach a critical slip value. At the same time, pressurized fluid is supplied to the wheel brake cylinders as necessary. Since the starting of the pump is subject to inertia, it is not possible to quickly supply the required pressure at the outlet of the pump during electric drive operation.

The present invention has been made in view of the above points, and its object is to provide a hydraulic braking system which is not affected by the demand for electrical energy and which allows continuous use of auxiliary fluid pressure for the operation of the wheel brakes. .

To achieve the above object, according to the present invention, a pressure accumulator is connected to an inlet of a fluid pressure power booster, and the pressure fluid pump is driven in accordance with the pressure within the pressure accumulator. That is, when the pressure accumulator reaches its maximum charge pressure, the pressure accumulator piston switches the electrical isolation contact to the open state. This cutoff contact is connected to a switching means for starting the electric drive source, and when it is in an open state, it switches the switching means to a non-operating state and stops the electric drive source. Furthermore, the brake pedal is provided with a connection contact, and when the brake pedal is actuated, the electric drive source is started by this connection contact. With the arrangement described above, the pressure accumulator is always maintained at a predetermined pressure, and the pressure fluid pump is immediately activated when the brake is applied. Therefore, if the brake pedal is pressed quickly,
The pressure necessary for the initiation of braking is obtained by the pressure accumulator, and when the pressure fluid pump is started, the necessary pressure is obtained primarily by this pressure fluid pump. Furthermore, according to the above configuration, since the electrical cutoff contact is directly operated by the piston of the pressure accumulator, even if a failure occurs in the electrical system of the system, the electrical cut-off contact is operated by the pressure fluid according to the pressure of the pressure accumulator. The pump can be controlled reliably. In other words, the pressure fluid pump can be reliably stopped when the pressure accumulator reaches a predetermined maximum charge pressure.
Excessive pressurization of the pressure accumulator and destruction of the hydraulic system can be prevented. At the same time, the pressure fluid pump can be activated in response to the operation of the brake pedal, making it possible to control the pressure fluid pump depending on the driving condition of the vehicle and quickly supplying hydraulic pressure to the fluid pressure power booster. can. Furthermore, with this arrangement, supplementary hydraulic energy is always available, the amount of which is always available is determined by the pressure accumulator. When the pressure in the pressure accumulator falls below a predetermined value, the pressure fluid pump is activated until the pressure in the pressure accumulator reaches the predetermined value again. The value of the pressure in the accumulator at which the pump starts can be preset and is set to a relatively low value so that the auxiliary fluid energy necessary for starting the pump is always available.

According to a preferred embodiment of the invention, a pressure control valve is provided between the outlet of the pressure fluid pump and the inlet of the pressure accumulator, by means of which:
The pressure sent from the pump outlet to the pressure accumulator inlet can be adjusted. In other words, this control valve acts to define the maximum charge pressure of the pressure accumulator. The maximum pressure to which the pressure control valve responds is preferably adjusted to approximately 80 bar. Furthermore, the pressure accumulator is preferably configured to switch off the pressure fluid pump when the charge pressure reaches approximately 20 bar. Further, as mentioned above, when a relatively low maximum charge pressure is required, it is advantageous to use a piston type pressure accumulator which has a simple construction and is inexpensive.

To protect the pressure fluid pump, a pressure relief valve is connected to the outlet of the pump, which relief valve defines the pressure at the outlet of the pump to a predetermined maximum value. In the brake system of this invention,
The pressure relief valve limits the maximum pressure to approximately 140 bar, for example.

Additionally, in a preferred embodiment of the invention, the outlet of the pressure fluid pump communicates via a check valve to a storage chamber of the hydraulic power booster, which storage chamber is separated from the non-pressurized supply storage tank. ing. The check valve is connected in parallel with the pressure control valve and is opened in the outflow direction of the pressure fluid pump. If the pressure accumulator drives the pressure fluid pump with a pressure higher than 20 bar, and the minimum reaction pressure of the pressure control valve is set to 80 bar, the fluid storage chamber of the fluid pressure power booster is activated when the brake is released. The pressure inside is approx.
100 bar, and the pressure inside the accumulator is approximately 20 bar. When the brake is applied, the relatively high pressure in the reservoir chamber is immediately reduced, and at the beginning of braking, the pressurized fluid necessary for braking operation is supplied by the pressure accumulator. In order to close the reservoir chamber as tightly as possible, the reservoir chamber is closed by a spring-loaded closing piston when the brake is in the released position. This occlusion piston isolates the reservoir chamber from the pressurized chamber of the power booster when the brake is released; It communicates with the tank.

Preferably, a slidable control piston is disposed coaxially with the closing piston within the pressure chamber of the hydraulic power booster. The end of the control piston adjacent the closing piston acts as a valve closing member and cooperates with a portion of the axial bore of the closing piston to act as a seated valve. Movement of the control piston after the axial bore of the closure piston is closed creates a fluid connection between the reservoir chamber and the pressure chamber. In order to precisely define the position of the control piston in the brake release position, the control piston is biased in the brake release direction by a compression spring. According to this embodiment, in the brake release position, the brake system becomes a closed central system and the hydraulic power booster is supplied with a predetermined pressure by the pressure fluid pump and the pressure accumulator. This pressure is supplied to the reservoir chamber of the hydraulic power booster and flows to the pressure chamber of the power booster during braking operations. During a braking operation, the pressure fluid pump is activated at the same time by means of a connecting contact operated by the brake pedal. Thus, when the brake is applied, an open central system is created, which is supplied with pressure primarily by the pressure fluid pump. Depending on the operating force applied to the brake pedal, pressure is generated in the pressurized chamber of the power booster, which, when exceeding a predetermined minimum reaction pressure, moves the booster piston in the direction of actuation, thereby connecting it to the power booster. Pressurize the master cylinder.

Also, in a preferred embodiment, a first brake circuit is connected to the pressurization chamber of the hydraulic power booster, and a second brake circuit is connected to the actuation chamber of the master cylinder connected downstream of the power booster. Ta. In these brake circuits, two wheel brake cylinders are operated during braking by the pressure generated in the hydraulic power booster, and the other two wheel brake cylinders are operated by the pressure generated in the actuation chamber of the master cylinder. Operated by pressure. The wheel brakes connected to the pressure chamber of the power booster and the wheel brakes connected to the working chamber of the master cylinder are distributed arbitrarily to the wheels of the motor vehicle. For example, a wheel brake cylinder connected to a pressure chamber is connected to a wheel brake on the front axle of a motor vehicle, and a wheel brake cylinder connected to an actuating chamber is provided on the rear axle. However, these wheel brake cylinders may be distributed in different ways depending on the state of the connected motor vehicle. For example, two brake circuits may be arranged diagonally, the wheel brake of one front wheel being actuated by pressure in the actuating chamber of the master cylinder, and the second wheel brake of the front wheel being operated by pressure in the actuating chamber of the master cylinder. Operated by pressure within the power booster's chamber. Further, one rear wheel brake is connected to a pressurizing chamber of a power booster, and the other rear wheel brake is connected to an operating chamber of a master cylinder. In other words, one front wheel brake and the diagonally corresponding rear wheel brake are combined to form one brake circuit. Further, a plurality of solenoid valves are inserted between the actuation chamber of the master cylinder and the pressure chamber of the hydraulic power booster, and these solenoid valves are operated by a slip control electronic circuit according to the rotational state of the wheel. Thereby, a brake system capable of slip control can be realized in a simple manner. The rotational movement of each wheel is detected and analyzed by appropriate sensors. Also, taking into account the dynamic axle load distribution of the motor vehicle, primarily the rotational movement of the front wheels is monitored and the pressure of each opposing wheel brake cylinder is adapted. A known brake pressure regulator may be inserted between the front wheel brake cylinder and the diagonally opposite rear wheel brake cylinder, which adjusts the brake pressure of the motor vehicle during deceleration of the vehicle. In consideration of operation, maintain rear wheel brake pressure below the wheel lock limit. This configuration provides a brake slip control system with a simple configuration requiring only a small number of solenoid valves.

When the accumulator piston is biased toward closing the isolation contact by a compression spring with adjustable force, the maximum charge pressure in the reservoir is the value required by the brake system. It is adjusted as follows. The brake system of the present invention is also configured to mechanically pressurize the working chamber of the master cylinder via the control piston and the closing piston in the event of a loss of auxiliary pressure supplied to the hydraulic power brake.
This is particularly important during emergency operation of the brake system, where sufficient deceleration of the vehicle must be achieved without the use of auxiliary forces.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In the figure, reference numeral 1 indicates a master cylinder, which is operated by a hydraulic power booster 2. The master cylinder 1 includes an actuation chamber 3 communicating with a housing port 4. A first brake circuit 5 is connected to the housing port 4, and this brake circuit operates to pressurize the two wheel brakes 6, 7 of the motor vehicle.

The master cylinder 1 is of a known type and cooperates with a master cylinder piston 8 coaxially and slidably guided in a cylinder bore 9 . piston 8
supports the cup-shaped seal 10, and
A compression spring 11 biases the brake in the direction of releasing the brake. The compression spring 11 is supported on a bowl-shaped spring holding member 12, into which the left end of the valve tappet 13 is inserted. The right end of the valve tappet 13 carries a closing element 14 which, together with a bore 15 formed in the master cylinder piston 8, acts as a so-called central valve. In the figure, the right end face of the master cylinder piston 8 defines a chamber 16 which is connected via a housing port 17 and a pressurized line 18 to a non-pressurized supply reservoir 19.
It is connected to the. The master cylinder piston 8 also has an axial bore 20 extending from the unpressurized chamber 16 to the rear face of the cup-shaped seal 10. Cup-shaped seal 1
0 acts so that the pressure fluid primarily flows from the chamber 16 to the working chamber 3 of the master cylinder 1.

The fluid pressure power booster 2 has a housing bore 2
The booster piston 22 is guided in the booster piston 1 and has a large-diameter step 23. The large-diameter stepped portion 23 cooperates with the housing bore 21 to form an annular chamber 24 and a pressure chamber 25 . A closing piston 27 with an axial bore 26 is arranged in the booster piston 22, the right end of which is designed as a valve closing member 28 which rests on a valve seat 29 in the brake release position shown. There is. The closing piston 27 is urged toward the valve seat 29 by a compression spring 30 . As a result, a liquid storage chamber 31 is provided inside the booster piston 22.
is formed, and the chamber 31 is fluidly connected to the annular chamber 24 via a radial bore 32. In the illustrated state, the closing piston 2
The left end of 7 extends into the chamber 16 in a sealed state. Inside the booster piston 22 , the chamber 16 accommodates a pressure member 33 , which is arranged coaxially with the closure piston 27 . Further, the pressure member 33 is formed to support a pressure transmission member 34 that is integrated with the master cylinder piston 8.

The booster piston 22 is connected to the brake pedal 35
It houses a control piston 36 which is slid by. The control piston 36 is the booster piston 2
2, and supports a closing member 37 at its left end. Closure member 3
7 forms a valve passage together with the port of the axial bore 26 of the closing piston 27 on the pedal 35 side. In the brake release position shown, the control piston 36 is held in position adjacent to the pedal 35 by a compression spring 38.

Brake pedal 35 has electrical contacts 39
is provided. This contact 39 is closed when the brake is applied, and connects the positive electrode 41 of the battery and the vehicle body 42 via the magnetic coil 40 of the magnetic relay. The magnetic coil 40 is connected to the connection contact 4
3, and this connection contact connects the motor 4.
4 becomes drivable. The electric motor 44 operates as a driving source for the pressure fluid pump 45 . Pump 45 is connected to housing port 48 of power booster 2 via check valve 46 and pressurizing line 47. Housing port 48 communicates with annular chamber 24 and further communicates with reservoir chamber 31 via radial bore 32 . The discharge side of the pressure fluid pump 45 is connected via a pressure control valve 49 to the inlet of a pressure accumulator 50 . The pressure accumulator 50 has a piston 51 biased by a compression spring 52. The pressure accumulator 50 is provided with connection contacts 53 by means of which the magnetic coil 40 can be connected to the electrical supply sources 41, 42 of the motor vehicle. At the outlet 54 of the pressure accumulator 50, another check valve 55 is provided. Further, a pressure relief valve 56 is provided at the outlet of the pressure fluid pump 45, and this relief valve is used to connect the pressure side of the pump and the liquid storage tank 19 when the pressure inside the pump exceeds a predetermined maximum pressure. Connect. Therefore, the outlet pressure of the pump 45 never exceeds a predetermined maximum pressure.

Furthermore, the pressure chamber 25 of the power booster 2
A second brake circuit 5 that pressurizes the wheel brakes 59 and 60 is connected to the housing port 57 that communicates with the
8 are connected.

Next, the operation of the brake system configured as above will be explained.

First, it is assumed that the automobile has not been running for a long time and that the pressure at the outlet 54 of the pressure accumulator 50 is approximately equal to atmospheric pressure. When the motor vehicle is driven, a positive current is sent to the electrode 41, for example via an ignition contact. Therefore, the magnetic coil 40 is energized via the electrical contact 53, the connecting contact 43 is switched to the closed position, and a voltage is supplied to the motor 44. As a result, the pressure fluid pump 45 is started, and the fluid storage chamber 31 of the fluid pressure power booster 2 is opened via the check valve 46.
supply pressure fluid to. As a result, the pressure within the liquid storage chamber 31 increases until it reaches the minimum reaction pressure of the pressure control valve 49. Pressure control valve 49
Assume that the minimum reaction pressure of is set at, for example, 80 bar. The connecting contacts 53 on the pressure accumulator 50 are adjusted to open at a pressure of approximately 20 bar and to switch off the motor 44 of the pressure fluid pump 45.

In this state, the pressure within the reservoir chamber 31 increases to approximately 100 bar and the fluid pressure within the pressure accumulator 50 to approximately 20 bar. Then, when the pressure in the pressure accumulator 50 reaches 20 bar, the connecting contact 53 is opened, thereby causing the magnetic coil 4
0 is no longer excited and the electric motor 44 stops.

When operating force is applied to the brake pedal 35,
Electrical contact 39 is closed, thereby re-energizing magnetic coil 40 and pressurized fluid pump 45.
also supplies pressure fluid. During braking, the control piston 36 moves to the left against the biasing force of the compression spring 38 until the valve closing member 37 comes into contact with the closing piston 27 and blocks the pressurizing chamber 25 of the power booster 2 from the liquid storage tank 19. Move to. When the operating force applied to the brake pedal 35 increases, the valve closing member 28 of the closing piston 27 closes against the valve seat 29.
, thereby establishing a fluid connection between the reservoir chamber 31 and the pressurization chamber 25 . A pressure proportional to the operating force applied to the brake pedal 35 is then generated in the pressurizing chamber 25, and this pressure is sent to the wheel brakes 59, 60 through the housing port 57. Due to the pressure generated in the pressure chamber 25, which is approximately determined by the frictional force,
The booster piston 22 moves in the operating direction, that is, to the left, and this movement is caused by the master cylinder piston 8
is transmitted to. The working chamber 3 of the master cylinder 1 is thereby pressurized. The pressure in the working chamber 3 is then transmitted to the wheel brakes 6, 7 via the housing port 4 and the first brake circuit 5.

In the event of damage to the pressure fluid pump 45 and the pressure accumulator 50, the control piston 36 is mechanically moved into abutment against the occluding piston 27 by braking, which presses against the pressure member 33 after having traveled a corresponding distance. . As a result, after the brake pedal has moved a structurally defined distance,
The working chamber 3 of the master cylinder 1 is mechanically pressurized. In this case, no pressure is generated in the pressure chamber 25 and the second brake circuit 58, and the wheel brakes 59, 60 are not activated.

Since the displacement of the pressure fluid pump 45 during brake start-up is not at its maximum due to the increased mass, the special purpose of the pressure accumulator 50 is to create a useful auxiliary fluid pressure immediately after the start of braking. be.

[Brief explanation of drawings]

The figure is a circuit diagram of a brake system according to an embodiment of the present invention. 1... Master cylinder, 2... Power booster, 35... Brake pedal, 44... Electric motor,
45... Pressure fluid pump, 49... Pressure control valve, 50... Pressure accumulator.

Claims (1)

[Claims] 1. A master cylinder, a fluid pressure power booster connected to the upstream side of the master cylinder, a pressure fluid pump having a controllable electric drive source, and a pressure fluid pump connected to an outlet of the pressure fluid pump. and a piston-type pressure accumulator connected to the inlet of the fluid pressure power booster, and a switching means connected to the electric drive source for starting the electric drive source; an electrical disconnection contact connected to the switching means and operated by a piston of the accumulator to switch the switching means into a deactivated state when the accumulator reaches a predetermined maximum charge pressure; and a brake. A fluid pressure brake system comprising: a connection contact that is provided on a pedal and starts the electric drive source when the brake pedal is stepped on. 2. A pressure control valve according to claim 1, characterized in that a pressure control valve is connected between the outlet of the pressure fluid pump and the inlet of the pressure accumulator, which determines the pressure difference therebetween. Hydraulic brake system. 3. Hydraulic brake system according to claim 2, characterized in that the minimum reaction pressure of the pressure control valve is set at approximately 80 bar. 4. Hydraulic brake system according to claim 2, characterized in that the maximum charge pressure is set at approximately 20 bar. 5. Claims 1 to 4, characterized in that a pressure relief valve for regulating the outlet pressure of the pressure fluid pump to a mechanically permissible maximum pressure is connected to the outlet of the pressure fluid pump. The fluid pressure brake system according to any one of the preceding items. 6. Hydraulic brake system according to claim 5, characterized in that the pressure relief valve is set to a maximum pressure of approximately 140 bar. 7 The outlet of the fluid pressure pump is connected to the liquid storage chamber of the fluid pressure power booster via a check valve, and the check valve is connected in parallel with the pressure control valve and opens in the discharge direction of the pressure fluid pump. The fluid pressure brake system according to any one of claims 2 to 6, characterized in that: 8. The hydraulic brake system according to claim 7, wherein the fluid storage chamber is closed by a closing piston biased by a spring in the brake release position. 9. In the brake release position, the liquid storage chamber and the pressurizing chamber of the fluid pressure power booster are connected to a non-pressurized supply liquid storage tank via the axial bore of the closing piston. A hydraulic brake system according to claim 8. 10 The pressurizing chamber accommodates a control piston that is disposed coaxially with the closing piston and is slid by the brake pedal, the end of the control piston on the closing piston side being formed as a valve closing member. and acting in conjunction with the axial bore of said occluding piston as a seated valve, such that a fluid connection between said reservoir chamber and pressurizing chamber is made when the control piston moves after occluding said axial bore. A hydraulic brake system according to claim 9, characterized in that: 11. The hydraulic brake system according to claim 10, wherein the control piston is biased in the brake release direction. 12 The first cylinder is installed in the operating chamber of the master cylinder.
A second brake circuit is connected to the pressurizing chamber of the fluid pressure power booster, and a second brake circuit is connected to the pressurizing chamber of the fluid pressure power booster, according to any one of claims 1 to 11. -hydraulic brake system. 13. The hydraulic brake system according to claim 1, wherein the piston of the pressure accumulator is biased in the direction of closing the electrical cutoff contact by a compression spring whose biasing force is adjustable. 14. Claim 12, characterized in that the actuation chamber is mechanically pressurized via the control piston and the closing piston in the event of a lack of auxiliary pressure supplied to the hydraulic power booster. Hydraulic brake system as described in. 15. Claim 1, wherein the first and second brake circuits are each connected to diagonally opposite wheel brakes.
The fluid pressure brake system according to item 2.