JPH1089529A - Passage selector valve for brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a passage selector valve which allows a reduction in the number of component parts of a brake booster and an improvement in its manufacturing efficiency. SOLUTION: A valve body 16 is formed with a communicating passage 18 which connects together two pressure chambers separated from each other and is connected to a negative-pressure lead passage, an air passage 19 for leading the atmospheric pressure to either of the two pressure chambers, a stop valve element 20 adapted to be brought in its second condition by the first energizing force of its spring part 23 to close the communicating passage 18 as well as open the air passage 19, and a plunger 26 adapted to be forcibly pressed on the stop valve element 20 by the energizing force of a spring 31 larger than the first energizing force to bring the stop valve element 20 into its first condition from its second condition to open the communicating passage 18 as well as close the air passage 19 and on the other hand to move by electromagnetic attractive force against the pressure by the spring 31 to bring back the stop valve element 20 into its second condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow path switching valve of a brake booster for increasing a depressing force input to a brake pedal in an automobile.

[0002]

2. Description of the Related Art Conventionally, various types of brake boosters of this type, such as an exhaust pressure type and an electric type, are known. In a passenger car, for example, a vacuum servo type as shown in FIG. Is often used. In brief, the brake booster is provided between a brake pedal 1 and a master cylinder 2 that constitutes the brake device, and uses a suction negative pressure in an intake manifold of an engine as a negative pressure source 3. ing. That is, the inside of the large-diameter housing 4 is divided by the diaphragm 5 into two front and rear pressure chambers 6, 7.
A push rod 8 is connected to the center of the brake pedal, and the brake pedal 1 is connected to one end of the push rod 8. The negative pressure source 3 is connected to the front pressure chamber 6 via a negative pressure introducing passage 10 provided with a check valve 9, and is connected to a rear side via a branch passage 11 branched from the negative pressure introducing passage 10. It communicates with the pressure chamber 7. Further, atmospheric pressure is introduced into the rear pressure chamber 7 through an atmosphere introduction passage 12. The branch passage 11 is provided with a solenoid-type negative pressure control valve 31 while the air introduction passage 1
2 is provided with a solenoid type on-off valve 32 for appropriately communicating or shutting off the rear pressure chamber 7 with the atmosphere.

The negative pressure control valve 31 opens the branch passage 11 to communicate the negative pressure introduction passage 10 with the rear pressure chamber 7, or closes the branch passage 11 and connects the front pressure chamber 6 to the rear pressure chamber 6. The communication with the side pressure chamber 7 is cut off.

In the above-described brake booster, during normal running of the vehicle, the on-off valve 32 and the negative pressure control valve 31 are closed, and the front pressure chamber in the large-diameter housing 4 is closed. 6, a negative pressure is supplied to the rear pressure chamber 7 by a valve built in the push rod 8, and the diaphragm 5 is maintained at the neutral position. On the other hand, at the time of a brake operation that requires deceleration, a controller (not shown) that detects information such as an inter-vehicle distance sensor closes the negative pressure control valve 31 and opens the open / close valve 32, thereby providing rear pressure. While introducing air into the chamber 7,
The communication between the front pressure chamber 6 and the negative pressure introduction passage 10 is blocked, and the inflow of atmospheric pressure from the rear pressure chamber 7 to the front pressure chamber 6 is prevented. As a result, a pressure difference occurs between the front and rear pressure chambers 6 and 7, and the diaphragm 5 presses the push rod 8 forward (to the right in the drawing) due to the negative pressure in the front pressure chamber 6, and as a result, the brake pedal 1 Operate the brake in the same way as input.

[0005]

However, in the conventional brake booster described above, in order to control the internal pressure of the front and rear pressure chambers 6, 7, a negative pressure control valve 3 is provided.
Since the configuration uses two valve devices such as the valve 1 and the on-off valve 32, the cost of parts of the entire device is high, and the pressure circuit is complicated, so that the working efficiency at the time of manufacturing is poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a flow path switching valve capable of reducing the number of components in a brake booster and improving the working efficiency during manufacturing. Aim.

[0007]

According to a first aspect of the present invention, a pressure difference is established between two pressure chambers separated from each other based on a negative pressure introduced from a negative pressure source. A flow passage switching valve that constitutes a brake booster that doubles a braking force by causing a pressure increase, wherein the communication passage connects the two pressure chambers to a main body and communicates with a negative pressure source; A first state in which an air passage for introducing atmospheric pressure into one of the two pressure chambers is provided, and the communication passage is opened and the air passage is closed;
The second state is established in which the communication passage is closed and the air passage is opened.

In such a configuration, when the flow path switching valve is in the first state, the two pressure chambers are communicated via the communication passage, and both of the two pressure chambers are connected to the negative pressure from the negative pressure source. Is introduced. When the flow path switching valve changes to the second state from this state, the atmospheric pressure is introduced into one of the two pressure chambers via the atmosphere passage, so that a pressure difference is generated between the two pressure chambers. Occurs. That is, only by the flow path switching valve,
The internal pressure difference between the two pressure chambers can be controlled.

According to the second aspect of the present invention, the opening / closing valve body for securing the second state based on the first urging force, and the opening / closing valve body using the second urging force larger than the first urging force. A plunger that presses against the body to change the second state to the first state, and that operates against the second urging force by electromagnetic attraction to recover the second state. It was provided.

In this configuration, when the flow path switching valve is in the first state, the on-off valve body and the plunger are pressed against each other by the first urging force and the second urging force acting in directions facing each other. This closes the atmosphere passage.
Therefore, leakage of atmospheric pressure from the atmosphere passage to the communication passage in the main body is reliably prevented.

Further, in the invention of claim 3, the on-off valve body is integrally formed of a bellows-like rubber material. In such a configuration, the flow path switching valve can be configured with fewer members.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing a brake booster using the flow path switching valve according to the present invention. That is, this brake booster is basically the same as that described in the prior art, and is provided between the brake pedal 1 and the master cylinder 2 to supply the negative suction pressure of the engine to a negative pressure source. 3 and a front pressure chamber 6 and a rear pressure chamber 7 separated by a diaphragm 5 inside a housing 4. A push rod 8 to which the brake pedal 1 is connected is connected to the center of the diaphragm 5. The negative pressure source 3 is connected to the front pressure chamber 6 via a negative pressure introduction passage 10 provided with a check valve 9, and is connected to the rear pressure chamber via a branch passage 11 branched from the negative pressure introduction passage 10. 7 is connected.

The branch passage 11 is provided with a passage switching valve 15 according to the present invention. This flow path switching valve 15
As shown in FIG. 1, the device includes a valve body 16 and a solenoid casing 17 connected to one end of the valve body. The valve body 16 has a first port 16 a opened at an end and communicating the inside with the atmosphere, a second port 16 b opened at the outer periphery and connected to the branch passage 11 and a rear pressure chamber 7. And a third port 16c connected to the third port 16c. As a result, a communication passage 18 for communicating the front pressure chamber 6 and the rear pressure chamber 7 and a first port 16a and a third port 16c are formed inside the valve body 16, and the atmosphere and the rear side are formed. Atmospheric passage 1 communicating with pressure chamber 7
9 are formed. Further, an opening / closing valve body 20 for opening and closing the communication passage 18 is provided inside the valve body 16. The opening / closing valve body 20 is formed of a rubber material into a stretchable bellows shape having a hollow interior, and is substantially separated from and seated on a stepped seat portion 21 formed in the communication passage 18 in the valve body 16. Annular valve part 22
And a spring portion 23 that urges the valve portion 22 in a direction to seat the seat portion 21 on the seat portion 21.

On the other hand, an electromagnetic coil 24 energized by a controller (not shown) and a fixed core 25 energized by energizing the electromagnetic coil 24 are housed in the solenoid casing 17 (note that the solenoid coil 17 is energized). In FIG. 1, it is shown integrally with the solenoid casing 17). Inside the electromagnetic coil 24, a plunger 26 that is attracted to the fixed core 25 by a guide member (not shown) and an electromagnetic attractive force generated by energizing the electromagnetic coil 24 is housed. The plunger 26 has a substantially cylindrical plunger body 27 that slides in the electromagnetic coil 24 in the axial direction.
A drive rod 28 provided at the center of the end face on the opening / closing valve body 20 side; and a drive rod 28 provided integrally with a distal end portion of the drive rod 28 to face the end face of the valve portion 22 of the opening / closing valve body 20 and open the opening. Disc-shaped control valve section 29 for opening and closing section 22a
And is constituted by. The drive rod 28 penetrates a guide wall 30 formed inside the valve body 16, and is provided between the guide wall 30 and the control valve portion 29 by the spring portion 23 of the on-off valve body 20. A spring 31 having a strong spring force is contracted. As a result, the plunger 23 is urged toward the on-off valve body 20,
The control valve portion 29 presses against the valve portion 22 and closes the opening 22a of the valve portion 22, and the valve portion 22 is
The on-off valve body 20 is contracted and deformed so as to be separated from the first valve body 1. The plunger 23 is provided between the guide wall 30 and the control valve portion 29 by the above-described electromagnetic attraction.
When the control valve unit 29 is moved toward the fixed core 25 against the bias of the control valve unit 29, a sufficient space is provided for the control valve unit 29 to be sufficiently separated from the on-off valve body 20.

In this embodiment having the above-described configuration, during normal traveling, power is not supplied from the controller (not shown) to the electromagnetic coil 24, and the plunger 26 is not driven.
As shown in the lower half of FIG. 1, the spring force of the spring 31 moves the valve portion 22 of the opening / closing valve body 20 via the control valve portion 29 against the spring force of the spring portion 23. It is in the first state separated from the seat 21.
At this time, the communication passage 18 is opened, and in the brake booster, the front pressure chamber 6 and the rear pressure chamber 7 communicate with each other. Negative pressure is introduced. Therefore, the diaphragm 5 is maintained in a substantially neutral position by the uniform negative pressure in the pressure chambers 6 and 7, and no force is applied to the push rod 8.

On the other hand, if it is determined that the brake control is necessary during the traveling, a controller (not shown) supplies
, And the fixed core 22 is excited. Then, the plunger 26 is moved by the spring 31 by electromagnetic attraction.
Moves to the fixed core 25 side against the urging force, and the second state shown in the upper half of FIG. 1 is obtained. That is, first, the control valve unit 2
9 moves in a direction away from the valve portion 22 of the on-off valve body 20, and the valve portion 22 is in a state of sitting on the seat portion 21.
Accordingly, the communication passage 18 is closed.
In the brake booster, the communication between the front pressure chamber 6 and the rear pressure chamber 7 is cut off, and the supply of the negative pressure to the rear pressure chamber 7 is cut off. Thereafter, the control valve portion 29 is connected to the on-off valve body 2.
The opening 22a of the valve portion 22 is opened away from the valve portion 22 of the valve body 0, and the atmosphere passage 19 is opened in the valve body 16 accordingly. Accordingly, atmospheric pressure, that is, positive pressure is introduced into the rear pressure chamber 7 instead of negative pressure, and the diaphragm 5 is bent and deformed toward the front pressure chamber 6 by the negative pressure.
As a result, the push rod 8 is pressed forward (to the right in FIG. 2), and as a result, a braking state is obtained.

As described above, in the above-described brake booster, the flow path switching valve 15 performs the functions of both the negative pressure control valve 31 and the on-off valve 32 described in the related art. That is, the flow path switching valve 15 alone controls the internal pressure difference between the front pressure chamber 6 and the rear pressure chamber 7. Therefore, the number of parts in the brake booster can be reduced as compared with the conventional case, and the parts cost of the entire apparatus can be reduced.
In addition, the pressure circuit can be simplified, the working efficiency during manufacturing such as piping work can be improved, and the reliability can be improved.

Further, in the above-mentioned flow path switching valve 15, when in the first state, the on-off valve body 20 and the plunger 26 act on the spring portion 2 which works in the direction facing each other.
Since the air passage 19 is closed by being pressed against each other by the spring force of the spring 3 and the spring force of the spring 31, it is possible to reliably prevent the atmospheric pressure from leaking from the air passage 19 to the communication passage 18 in the main body. Can be. Moreover, the structure is simple. Therefore, a highly reliable flow path switching valve 15 with a simple structure can be provided.

The flow path switching valve 15 is not limited to the one shown in FIG. 1. For example, the opening / closing valve body 20 is moved in the operating direction of the plunger 26 so as to be moved to the seat portion 21 of the valve body 16. The second port 16b
A valve member that alternately opens the communication passage 18 and the air passage 19 by opening and closing the valve, a spring that constantly urges the valve member so that the valve member is seated on the seat portion 21, and the like. It is also possible to replace the two members with the urging member. The use of the above-described on-off valve body 20 can reduce the cost of the flow path switching valve 15, and as a result, the cost of the brake booster can be further reduced.

[0020]

As described above, according to the first aspect of the present invention, since the internal pressure difference between the two pressure chambers in the brake booster can be controlled by the flow path switching valve alone, the brake By reducing the number of parts of the booster, it is possible to reduce the parts cost of the entire apparatus. Further, since the pressure circuit is simplified, the working efficiency at the time of manufacturing the brake booster is improved, which can also reduce the cost of the device. Further, the simplification of the pressure circuit can improve the reliability of the device.

According to the second aspect of the invention, when the flow path switching valve is in the first state, the on-off valve body and the plunger act on the first biasing force and the second biasing force acting in directions facing each other. Thus, the atmosphere passage is closed by being pressed against each other, and leakage of the atmospheric pressure from the atmosphere passage to the communication passage in the main body is reliably prevented. Therefore, the reliability of the flow path switching valve is improved. Moreover, a highly reliable flow path switching valve with a simple structure can be provided.

According to the third aspect of the present invention, the on-off valve body is integrally formed of a bellows-like rubber material so that the flow path switching valve can be configured with a smaller number of members. The manufacturing cost of the valve can be reduced, and at the same time, the price of the brake booster can be reduced.

[0023]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a flow path switching valve according to an embodiment of the present invention, in which a lower half shows a first state and an upper half shows a second state.

FIG. 2 is a schematic configuration diagram showing a brake booster.

FIG. 3 is a schematic configuration diagram showing a conventional brake booster.

[Explanation of symbols]

 Reference Signs List 3 negative pressure source 6 front pressure chamber 7 rear pressure chamber 10 negative pressure introduction passage 15 flow path switching valve 18 communication passage 19 atmospheric passage 20 opening / closing valve body 24 electromagnetic coil 26 plunger

Claims (3)

[Claims] A flow path switching valve constituting a brake booster for doubling a braking force by causing a pressure difference between two pressure chambers separated from each other based on a negative pressure introduced from a negative pressure source. A communication path communicating the two pressure chambers with a main body and communicating with a negative pressure source;
An air passage for introducing atmospheric pressure into one of the two pressure chambers, a first state in which the communication passage is opened and the air passage is closed, and the communication passage is closed. And a second state in which the air passage is opened. 2. An on-off valve body for securing the second state based on a first urging force, and the second on-off valve body being pressed against the on-off valve body by a second urging force larger than the first urging force. And a plunger that changes the state of No. 2 to the first state, operates against the second urging force by electromagnetic attraction, and recovers the second state. The flow path switching valve for a brake booster according to claim 1. 3. The brake booster according to claim 2, wherein the on-off valve body is integrally formed of a bellows-like rubber material.