JPH08207744A - Brake booster coping with automatic brake - Google Patents

Abstract

PURPOSE: To provide a brake booster coping with an automatic brake, preventing sudden braking even in case of the failure of a solenoid valve for controlling automatic brake action, without impairing a normal braking function by a brake pedal. CONSTITUTION: A power chamber 19 constituted of a pressure chamber 28 supplied with lead-in pressure from a pressure source 11, and a movable wall 34 displaced by differential pressure between the lead-in pressure and atmospheric pressure and energized by an operating rod 24 is mounted to a booster body 1 boosting operating force inputted to the operating rod 24 from a brake pedal 23. The lead-in pressure to the pressure chamber 28 is controlled by a control valve 29 interposed in a passage 12 between the pressure chamber 28 and the pressure source 11 so as to open the pressure chamber 28 to the air at the normal time and to communicate the pressure chamber 28 with the pressure source 11 at the time of action, and a fail-safe valve 30 interposed between the control valve 29 and the pressure source 11 so as to communicate the control valve 29 with the pressure source 11 side at the normal time and to open the control valve 29 side to the air at the time of the failure of the control valve 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster device having a function as an automatic brake, and more particularly to pressure control thereof.

[0002]

2. Description of the Related Art A booster device for boosting a brake operating force input from a brake pedal to an operating rod by changing the volume of a pressure chamber formed therein is already known. For example, JP-A-5-22941
In the brake booster disclosed in Japanese Patent Publication No. 9, a positive pressure chamber is provided in a negative pressure chamber formed in a booster, and a flow path communicating with the atmosphere is connected to this positive pressure chamber via a solenoid valve. ing. Then, when the automatic braking is activated, the solenoid valve is opened to introduce the atmosphere into the positive pressure chamber, and the same hydraulic pressure as that generated by the operation of the brake pedal is also generated during the automatic braking.

[0003]

[To solve the problem to be solved by the invention]
In the brake booster disclosed in Japanese Patent No. 229419, the same hydraulic pressure is generated during the automatic brake operation and during the normal brake operation by the brake pedal, so that the braking force is strong even during the automatic brake operation. Therefore, if the solenoid valve that controls the introduction of the atmospheric pressure into the negative pressure chamber fails and is kept in the atmosphere-introduced state, the brake remains applied and the vehicle cannot start. Further, if the automatic braking that is not intended by the driver is applied during traveling due to the failure of the electromagnetic valve, hydraulic pressure is generated when the full capacity of the booster is used, resulting in sudden braking.

[0004]

In view of the above, according to the present invention, a booster body for boosting a brake operating force input from a brake pedal to an operating rod and a movable wall attached to the operating rod separate the atmosphere from the atmosphere. A power chamber that has a pressure chamber that is formed and that applies an operating force to the operating rod independently of the operation of the brake pedal by the displacement of the movable wall due to the pressure difference between the pressure introduced into the pressure chamber and the atmospheric pressure; Is installed in the pressure source, which is the supply source of the introduction pressure to the pressure chamber, and the flow path between the pressure chambers.The pressure chamber is normally open to the atmosphere, and the pressure chamber communicates with the pressure source during operation. And a control valve for controlling. According to a second aspect of the invention, in the first aspect of the invention, the booster body is an air booster, and the pressure chamber of the power chamber is formed to have a smaller volume than the volume of the booster body. Claim 3
According to the invention described in claim 1, in the invention described in claim 1, the control valve and the pressure source are normally connected to each other so that the control valve and the pressure source side communicate with each other, and when the control valve fails, the control valve side is opened to the atmosphere. The sail valve was installed. According to a fourth aspect of the present invention, in the first or third aspect of the present invention, the pressure source is an intake manifold of an engine that generates negative pressure, and an accumulator is connected to a flow path between the intake manifold and the control valve.
A check valve was provided in the flow path between the accumulator and the intake manifold to allow only the flow to the intake manifold side.

[0005]

According to the first aspect of the present invention, the flow path is provided between the pressure chamber separated from the atmosphere by the movable wall attached to the operating rod and the pressure source supplying the introduction pressure to the pressure chamber. When the mounted control valve operates, the pressure chamber and the pressure source communicate with each other, and the introduction pressure is supplied from the pressure source to the pressure chamber. The movable wall is displaced by the pressure difference between the introduction pressure and the atmospheric pressure, and the operating rod moves in the displacement direction of the movable wall. That is, the urging force is applied to the operating rod independently of the operation of the brake pedal.

According to the second aspect of the present invention, since the pressure chamber of the power chamber is formed to have a smaller volume than the volume of the booster main body for pneumatic pressure, the urging force generated by the power chamber to the operating rod is increased. Is smaller than the urging force applied to the operating rod.

According to the third aspect of the present invention, the fail-sale is such that the control valve and the pressure source side are normally communicated with each other between the control valve and the pressure source, and the control valve side is opened to the atmosphere when the control valve fails. Since the valve is provided, when the control valve fails, the fail-sale valve cuts the introduction pressure from the pressure source to the pressure chamber, and the urging force to the operating rod is lost.

According to the invention described in claim 4, an accumulator is connected to the flow passage between the intake manifold and the control valve, and only the flow passage to the intake manifold side is allowed in the flow passage between the accumulator and the intake manifold. Since the check valve is installed, the negative pressure from the intake manifold is accumulated in the accumulator when the control valve is open to the atmosphere.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 100 indicates a brake booster device. The brake booster device 100 is of a so-called tandem type, and operates independently of the operation of the booster body 1 and the brake pedal 23 that boost the brake operation force input to the operating rod 24 connected to the brake pedal 23. Power chamber 19 that applies an operating force to rod 24, and intake manifold 1 as a pressure source that serves as a supply source of the introduction pressure to power chamber 19.
Control valve 29 provided in the flow passage 12 connected to the valve 1, a fail-sale valve 30 provided in the flow passage 12 between the control valve 29 and the intake manifold 11, and a control valve 30 between the control valve 30 and the fail-sale valve 30. An accumulator 31 arranged in the flow path 12 and an engine control unit (hereinafter, referred to as “ECU”) that controls the control valve 29 and the fail-sale valve 30.
32). This brake booster device 10
0 is compatible with automatic braking.

A center plate 2 is provided inside the booster body 1.
Is divided into two spaces by the rear, and a substantially cylindrical valve body 3 penetrates the center of the center plate 2 slidably. A front power piston 4 and a rear power piston 5 are provided on the outer peripheral portion of the valve body 3. A front diaphragm 6 and a rear diaphragm 7 are arranged so as to be stretched over the booster body 1 and the valve body 3, respectively, on the back surfaces of the pistons 4 and 5. With these configurations, a constant pressure chamber A and a variable pressure chamber B are formed in front and rear of the front diaphragm 6, and a constant pressure chamber C and a variable pressure chamber D are formed in front and rear of the rear diaphragm 7, respectively. The constant pressure chambers A and C communicate with each other through a constant pressure passage 8 formed in the valve body 3, and the variable pressure chambers B and D communicate with each other through a variable pressure passage 10 formed in the valve body 3.

A nipple 9 communicating with the constant pressure chamber A is attached to the front panel 1A of the booster body 1. An intake manifold 11 communicates with the nipple 9 via a flow path 12 to make both the constant pressure chambers A and C under negative pressure.

A well-known valve mechanism 15 including a vacuum valve 13 and an atmospheric valve 14 is provided in the valve body 3.
The space on the outer side of the atmosphere valve 14 communicates with the constant pressure chamber A through a constant pressure passage 16 formed in the valve body 3 so as to extend in the axial direction, and the space between the atmosphere valve 14 and the vacuum valve 13 is , Communicates with the variable pressure chamber D via a variable pressure passage 17 provided in the valve body 3. An inner side of the vacuum valve 13 communicates with an atmosphere introduction port of a power chamber 19 described later via a pressure passage 18 formed in the valve body 3. Further, the valve body 3 is attached to the atmosphere valve 14 by the coil spring 25.
Is urged in the closing direction (to the right in FIG. 1).

A push rod 20 that is connected to a master cylinder (not shown) is slidably supported on the booster body 1. The push rod 20 includes an operating rod 24 connected to a brake pedal 23 via a reaction disc hub 21 and a valve plunger 22.
Are integrated. A breathable silencer 26 and a filter 27 are fixed to the operating rod 24 located in the pressure passage 18.

The power chamber 19 is attached to the rear end 3A of the valve body 3 by fastening its sleeve 19A. A pressure chamber 28 is formed by the movable wall 34 inside the sleeve 19A. The pressure chamber 28 is formed in the chamber case 19B as shown in FIG.
The volume of the constant pressure chambers A and C is set to be smaller than the total volume of the constant pressure chambers A and C.

The movable wall 34 has a piston plate 34A fixed to an operating rod 24 inserted through the power chamber 19, a center fixed to the operating rod 24 and an outer periphery fixed to the chamber case 19B, and a rear side of the piston plate 34A. The diaphragm 34B arranged in
It is composed of a spacer 34C fixed to the piston plate 34A. The movable wall 34 is displaced by the pressure difference between the pressure introduced into the pressure chamber 28 and the atmospheric pressure. Here, normally, there is a gap S between the spacer 34C and the case inner end surface 19C, and When a negative pressure is supplied from the intake manifold 11, the spacer 34C moves to the case inner end surface 19
It is designed to be displaced in the direction of contacting C. Therefore, the operating rod 24 can slide by an amount corresponding to the interval S in the operation direction indicated by the arrow a independently of the operation of the brake pedal 23 shown in FIG.

A ring-shaped sealing member 35 is inserted and fitted in the vicinity of a penetrating portion between the chamber case 19B and the operating rod 24. In the sleeve 19A, a plurality of atmosphere introducing ports 19D communicating with the constant pressure passage 18 are formed in the circumferential direction.

The control valve 29 and the fail-sale valve 30 shown in FIG. 1 are electromagnetic valves and are under the control of the ECU 32. The control valve 29 connects the pressure chamber 28 with the flow path 1
2 is provided, and normally the pressure chamber 28 is opened to the atmosphere,
When energized by an ON signal from the ECU 32, the pressure chamber 2
8 is communicated with the intake manifold 11 to make a negative pressure. The fail-sale valve 30 normally connects the control valve 29 and the intake manifold 11 to each other, and
It is designed to open to the atmosphere by the ON signal from.
Check valves 36A and 36B that allow only the flow to the intake manifold 11 side are arranged in the flow passage 12 in front of the fail-sale valve 30 and the nipple 9, respectively.

The ECU 32 is composed of a well-known microcomputer as a main part. Here, the ECU 32 judges a failure of the control valve 29 and applies an ON signal to the control valve 29 and the fail-sale valve 30. When the automatic brake signal is input, the ECU 32 applies an ON signal to the control valve 29 and, when it determines that the control valve 29 has failed, the fail-sale valve 3
An ON signal is applied to the fail-sale valve 30 to open 0 to the atmosphere. Further, the control circuit in the ECU 32 has a dual system circuit structure in which even if one system has a defect, the other system can cover it.

Here, the failure judgment of the control valve 29 means E
The automatic braking mode and the hydraulic pressure data generated by the power chamber 19 in the same mode are input to the CU 32 in advance, and the opening degree of the brake pedal 23 and the hydraulic pressure of the brake oil are detected by a sensor (not shown) to automatically In the brake mode, or when there is no stored brake pedal opening and the stored hydraulic pressure data indicates the stored hydraulic pressure data, it is determined that the control valve 29 has failed.

The operation of the brake booster device 100 compatible with such automatic braking will be described. When an engine (not shown) is started, as shown in FIG. 1, the flow path 12 and the accumulator 31 are in communication with each other, the accumulator 31 is negatively pressurized, and the constant pressure chambers A and C are also introduced through the nipple 9. It is made negative by negative pressure.

(Normal Brake Operation) Brake Pedal 2
When 3 is stepped on and brake operation force is applied, as shown in FIG.
As shown in, the operating rod 24 slides in the operating direction indicated by the arrow a, the atmospheric valve 14 is opened, and the vacuum valve 15 is closed. Then, the power chamber 19
It slides in the direction a together with the valve body 3. At this time, the interval S (stroke) is set to be sufficiently larger than the stroke when the atmospheric valve 14 is fully opened, so that S = 0 will not occur. If the sliding of the operating rod 24 continues after this, the power chamber 19 slides integrally with the operating rod 24, the vacuum valve 13 shown in FIG. It is opened by an amount equivalent to the amount of movement, and the atmosphere is introduced into the constant pressure passage 18 from the atmosphere introduction port 19D, and the variable pressure chambers B and D are brought to atmospheric pressure.

Therefore, the constant pressure chambers A and C to which the negative pressure is supplied
And a differential pressure is generated between the variable pressure chambers B and D to which the atmospheric pressure is supplied, the body valve 3 moves forward against the spring force of the coil spring 25, and the push rod 20 as in the known brake booster device. It is possible to obtain a predetermined assist force from. In the case of normal braking operation, the control valve 29
1 is in the off state in which it is open to the atmosphere as shown in FIG. 1, the pressure chamber 28 is brought to the atmospheric pressure, and the movable wall 34 is displaced by the sliding of the operating rod 24.

(Operation during automatic braking) In the ECU 32,
When the automatic brake signal is input, the ON signal is applied to the control valve 29 that has occupied the atmosphere open state shown in FIG.
As shown in FIG. 5, the valve 29 is in an ON state in which the intake manifold 11 and the pressure chamber 28 communicate with each other, and a negative pressure is supplied to the pressure chamber 28. At this time, since the accumulator 31 has already been made negative pressure, when the control valve 29 is turned on, the pressure chamber 28 is immediately made negative pressure, and the operation delay is eliminated.

When the pressure chamber 28 is made negative, the movable wall 34 stretched with a gap S between the case inner end surface 19C shown in FIG. 2 faces the case inner end surface 19C as shown in FIG. And the operating rod 24 slides in the operating direction indicated by the arrow a. When the operating rod 24 slides, the vacuum valve 13 shown in FIG.
4 is opened by an amount corresponding to the movement amount of 4, and the atmosphere is introduced into the constant pressure passage 18 from the atmosphere introducing port 19D, so that the pressure in the variable pressure chambers B and D becomes atmospheric pressure. Therefore, an assist force corresponding to the sliding amount of the operating rod 24 is generated, and the automatic braking is applied. The assisting force here is an output smaller than the assisting force generated by the normal braking operation, and sudden braking does not occur.

On the other hand, even though the automatic brake signal is not output, the control valve 29 is stuck in the ON state where it communicates with the intake manifold 11, and the hydraulic pressure of the brake oil becomes the hydraulic pressure during the automatic brake operation. And EC
U32 determines that the control valve 29 is out of order. When it is determined that there is a failure, the ON signal is applied to the fail-sale valve 30 which is in the OFF state shown in FIG. Then, as shown in FIG. 6, the fail-sale valve 30 is in the ON position for opening to the atmosphere. Therefore, the atmospheric pressure is supplied to the pressure chamber 28, the operation of the automatic brake is released, and the normal brake operation by the brake pedal 23 becomes possible.

Further, the control valve 29 and the fail-sale valve 3
When a failure occurs in which the ON signal is not applied to 0 due to disconnection or the like, the control valve 29 and the fail sail 30 are returned to the OFF state by the return springs 37 and 38 as shown in FIG. 7. Therefore, since the control valve 29 is opened to the atmosphere, the atmosphere is introduced into the pressure chamber 28, the automatic brake is deactivated, and the normal braking operation by the brake pedal 23 becomes possible.

[0027]

According to the invention of claim 1, since the operating force can be applied to the operating rod independently of the operation of the brake pedal by the power chamber, the inside of the booster body is described in the section of the prior art. As described above, it is not necessary to refurbish, the normal booster body can be easily used, the cost can be reduced, and the reliability of the device can be improved. In addition, since the control valve normally opens the pressure chamber to the atmosphere, even if a failure occurs that the control valve cannot be energized, the power chamber will not operate and the normal braking function of the brake pedal will not be achieved. The safety of the equipment can be improved.

According to the second aspect of the present invention, the urging force to the operating rod generated in the power chamber is
It is less than the urging force generated on the booster body to the operating rod. Therefore, even if the automatic brake operates, the full capacity of the booster body is not used, so that sudden braking due to excessive hydraulic pressure is not generated and safety is improved.

According to the third aspect of the present invention, when the control valve fails, the fail-sale valve cuts the introduction pressure from the pressure source to the pressure chamber, and the urging force to the operating rod is lost, so that the control valve fails. The automatic brake can be released at any time, and the braking function by the normal brake pedal can be secured, improving the safety of the device.

According to the fourth aspect of the invention, when the control valve is open to the atmosphere, a negative pressure from the intake manifold is accumulated in the accumulator provided in the flow path between the intake manifold and the control valve. When the control valve operates to connect the intake manifold and the pressure chamber, the negative pressure is immediately supplied to the pressure chamber, and it is possible to prevent the operation delay of the automatic brake when the negative pressure is supplied.

[Brief description of drawings]

FIG. 1 is a side view of a brake booster device for automatic braking showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a power chamber which is a main part of the present invention.

FIG. 3 is a cross-sectional view showing the operation of the power chamber during the automatic brake operation.

FIG. 4 is a cross-sectional view showing the operation of the power chamber and valve body during normal brake operation.

FIG. 5 is an enlarged view showing the states of the control valve and the fail-sale valve when the automatic brake is activated.

FIG. 6 is an enlarged view showing a state of the fail-sale valve when the control valve fails.

FIG. 7 is an enlarged view showing an off state of the control valve and the fail sail valve.

[Explanation of symbols]

 1 Booster Main Body 11 Pressure Source (Intake Manifold) 12 Flow Path 19 Power Chamber 23 Brake Pedal 24 Operating Rod 28 Pressure Chamber 29 Control Valve 30 Fail Sale Valve 31 Accumulator 34 Movable Wall 36A, 36B Check Valve A, C Constant Pressure Chamber (Pressure) Room) B, D Transformer room (pressure room) 100 Brake booster device

Claims (4)

[Claims] 1. A booster body for boosting a brake operating force input from a brake pedal to an operating rod, and a pressure chamber separated from the atmosphere by a movable wall attached to the operating rod. To the operating chamber independently of the operation of the brake pedal due to the displacement of the movable wall due to the pressure difference between the pressure introduced to the operating chamber and the atmospheric pressure, and to the pressure chamber. A pressure source that serves as a supply source of the introduction pressure, and is interposed in a flow path between the pressure chamber and the pressure source, and normally opens the pressure chamber to the atmosphere, and during operation, the pressure chamber and the pressure source A brake booster device for automatic braking, which is provided with a control valve for communicating with each other. 2. The booster body is a pneumatic booster,
The brake booster device according to claim 1, wherein the pressure chamber of the power chamber is formed to have a volume smaller than that of the booster. 3. The control valve is interposed between the control valve and the pressure source, and normally connects the control valve and the pressure source side. When the control valve fails, the control valve side is opened to the atmosphere. The brake booster device according to claim 1, further comprising a fail-sale valve. 4. The pressure source is an intake manifold of an engine for generating a negative pressure, and an accumulator connected to a flow path between the intake manifold and the control valve, and between the accumulator and the intake manifold. 4. The brake booster device for an automatic brake according to claim 1 or 3, further comprising a check valve which is interposed in the flow path and allows only the flow to the intake manifold side.