JPH09207754A - Brake booster - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To appropriately reduce the pressure of the master cylinder when there is a demand for reducing the pressure of the master cylinder, and to sufficiently exert a brake boosting action in the case of a brake operation by a normal depression. To provide a brake booster that can. A brake booster (12) is provided with a variable pressure chamber (6) and a negative pressure chamber (7) partitioned by a diaphragm (21), and an electronic control unit (24) for adjusting the pressure in both chambers (6, 7). A communication control valve 3 and a ventilation control valve 4 which are driven to open or close by a signal from the are provided. Communication control valve 3
Is provided in a communication passage 23 that communicates between the variable pressure chamber 6 and the negative pressure chamber 7, a second check valve 25 is provided in the communication passage 23 in parallel with the communication control valve 3, and a first check valve 11 is provided in a conduit 29. Is provided. Connection part 23 on the negative pressure chamber 7 side of the communication passage 23
a is directly connected to the negative pressure chamber 7. Further, the ventilation control valve 4 is provided in a ventilation path 27 connected to the variable pressure chamber 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster for increasing braking force and improving braking performance.

[0002]

2. Description of the Related Art Conventionally, a so-called brake booster for increasing the depressing force of a brake pedal has been attached to a vehicle in order to reliably perform a brake operation by a driver.
This brake booster increases the depressing force of the brake pedal and applies a large pressure to the master cylinder side by utilizing, for example, the difference between the negative pressure on the intake side of the engine and the atmospheric pressure.

Further, in recent years, a technique has been proposed in which anti-skid control is performed using this brake booster. This is because when there is a pressure reduction request for the wheel cylinder during anti-skid control, that is, when there is a pressure reduction request for the master cylinder that is the pressure source of the wheel cylinder,
By introducing air into the negative pressure chamber, the pressure difference between the negative pressure chamber and the variable pressure chamber is reduced, and the pressure applied to the master cylinder (by the brake booster) is weakened, thereby reducing wheel slip. This is a technique for improving the braking force (see Japanese Patent Laid-Open No. 63-68451).

[0004]

However, in this technique, for example, when anti-skid control is performed, atmospheric pressure is introduced into the negative pressure chamber to reduce the pressure in the master cylinder, so that the pressure in the negative pressure chamber is large. Since the pressure is close to atmospheric pressure, the function of the brake booster may not be fully exerted. For example, when an engine stall occurs, or when the accelerator and brake are pressed at the same time,
When the negative pressure is not output, the negative pressure cannot be introduced into the negative pressure chamber, so that the brake boosting effect of the normal brake operation (normal brake) may not be achieved.

The present invention has been made in view of the above problems, and when the master cylinder is requested to be depressurized, the master cylinder can be appropriately depressurized, and it is sufficient in the case of a normal brake pedal operation. It is an object of the present invention to provide a brake booster capable of exerting a brake boosting action.

[0006]

In the brake booster according to the first aspect of the present invention, negative pressure is introduced into the negative pressure chamber from a negative pressure source such as the intake side of the engine, and the variable pressure chamber includes, for example, Since a high pressure (more than negative pressure) is introduced from a pressure source such as atmospheric pressure, the acting force applied to the brake pedal by the driver's brake operation can be boosted and added to the brake fluid on the master cylinder side. .

In particular, according to the present invention, a communication passage communicating between the negative pressure chamber side and the variable pressure chamber side is provided with a communication control valve for controlling the opening / closing of the communication passage, and a ventilation path for introducing the atmosphere or the like into the variable pressure chamber. Since a ventilation control valve that controls the opening and closing of the ventilation path is provided in the engine, the negative pressure can be controlled by controlling the opening / closing state of both valves according to a command signal during vehicle control such as during anti-skid control. The pressure in the chamber and the variable pressure chamber can be adjusted appropriately.

Therefore, for example, when there is a pressure reduction request for the master cylinder, for example, by opening the communication control valve and closing the ventilation control valve, the pressures of the negative pressure chamber and the variable pressure chamber are increased, as will be described in detail later. The difference can be reduced quickly. Therefore, the pressure of the master cylinder (master cylinder pressure) can be quickly reduced, so that the braking force can be improved during anti-skid control, for example. Further, since the brake booster can be used for the anti-skid control, it is not necessary to increase the master cylinder pressure more than necessary, so that the rating of the pump of the hydraulic circuit can be lowered. Furthermore, since the atmosphere is not directly introduced into the negative pressure chamber as in the past,
For example, even if there is a pressure reduction request for the master cylinder during anti-skid control, the negative pressure chamber is kept at a negative pressure during that time. Therefore, for example, even when an engine stall or the like occurs and no negative pressure is generated, for example, by closing the communication control valve and opening the ventilation control valve, a pressure difference between the negative pressure chamber and the variable pressure chamber is generated, and the normal pressure is generated. The effect of boosting the brake during braking can be exerted. In addition, the pressure difference between the negative pressure chamber and the variable pressure chamber can be set appropriately by adjusting the open / closed state of the communication control valve and the ventilation control valve, so that it can be adjusted depending on the number of people in the vehicle and the state of luggage, for example. Thus, the effectiveness of the brake booster can be adjusted.

Next, the operation of the communication control valve and the ventilation control valve of the present invention will be described with reference to an example using engine negative pressure and atmospheric pressure. Note that the communication control valve and the ventilation control valve are not conventional mechanical valves that open and close mechanically in conjunction with the push rod when the brake pedal is stepped on. It is a control valve that is drive-controlled according to an operating state.

As shown in FIG. 1 (a), a brake booster (brake booster) having a conventional first mechanical valve 1 and a second mechanical valve 2 and a communication control valve 3 and a ventilation control valve 4 of the present invention.
Then, when the brake pedal 5 is depressed (time point t1 in FIG. 2), the first mechanical valve 1 is closed, the second mechanical valve 2 is opened, and the ventilation control valve 4 is opened, so that the variable pressure chamber 6 is opened. When the atmosphere is introduced, the pressure in the variable pressure chamber 6 (shown by the solid line in FIG. 2A) increases. At this stage, since the communication control valve 3 remains closed, the pressure in the negative pressure chamber 7 (shown by the broken line in FIG. 2A) does not increase. Therefore, the master cylinder pressure is
As shown in (b), it rapidly increases from the time t1 by the action of the brake booster.

Next, when there is a pressure reduction request for the master cylinder 9 (time t2 in FIG. 2), the communication control valve 3 is opened and the ventilation control valve 4 is closed, as shown in FIG. 1 (b). Because
Although the atmosphere is not introduced into the variable pressure chamber 6, the air in the variable pressure chamber 6 flows out to the negative pressure chamber 7 side, and the pressure in the variable pressure chamber 6 rapidly increases toward the engine negative pressure as shown in FIG. Fall to. Further, in the negative pressure chamber 7, the pressure temporarily increases due to the inflow of air from the variable pressure chamber 6, but thereafter, the pressure decreases like the variable pressure chamber 6. Therefore, since the pressure difference between the negative pressure chamber 7 and the variable pressure chamber 6 is rapidly reduced, the action of the brake booster is weakened, and
As shown in (b), the master cylinder pressure also decreases rapidly.

That is, according to the present invention, due to such an action, the delay in decompression of the master cylinder 9 can be prevented, and as shown in FIG. 2 (a), the pressure in the negative pressure chamber 7 is the master cylinder pressure. Since the pressure is close to the pressure of the negative pressure source while the reduction control is performed, the function of the brake booster can be exerted even if an engine stall or the like occurs.

When the ventilation control valve 4 is abolished, both chambers 6 and 7 can be operated even when the master cylinder 9 is requested to be depressurized.
Since the pressure difference in the pressure gradually decreases, for example (Fig. 2 (b)
The master cylinder pressure does not start to decrease until time t3 (as indicated by the broken line in FIG. 2), and the pressure reduction timing is delayed.

In the brake booster of the second aspect, the connecting portion on the negative pressure chamber side of the communication passage is provided on the negative pressure chamber side of the first check valve. Therefore, even when the negative pressure is not generated due to the engine stall or the like, the negative pressure chamber side of the first check valve is maintained at the predetermined negative pressure before the engine stall. Therefore, in the case of the normal brake, as shown in FIG. 1A, the communication control valve 3 is closed and the ventilation control valve 4 is set to open, so that the negative pressure chamber 7 and the variable pressure chamber 6 are separated from each other. Because of the pressure difference,
The function of the brake booster can be fully exerted.

This operation will be described with reference to FIG. 3 by taking an example similar to that of FIG. As shown in FIG. 3A, when the brake pedal 5 is depressed at time t1, the communication control valve 3 is set to be closed and the ventilation control valve 10 is set to be open, so that the atmosphere is introduced into the variable pressure chamber 6. The pressure in the transformer chamber 6 increases. At this time, when an engine stall occurs (time point te), the engine negative pressure rapidly decreases (approaches atmospheric pressure). When there is a pressure reduction request for the master cylinder 9 at time t2, the communication control valve 3 is set to open and the ventilation control valve 10 is set to closed.
Air is introduced from the variable pressure chamber 6 into the negative pressure chamber 7 while the introduction of the atmosphere into the variable pressure chamber 6 is blocked. As a result, the pressure in the variable pressure chamber 6 decreases and the pressure in the negative pressure chamber 7 increases, and the pressures converge to almost the same value. Therefore, the master cylinder pressure rapidly decreases from time 2 when there is a pressure reduction request.

As described above, according to the present invention, by setting the position of the connecting portion on the negative pressure chamber side of the communication passage, even if the negative pressure is not generated due to the engine stall or the like, the negative pressure chamber 7 (normal and Since a constant negative pressure can be maintained with certainty (although it is slightly different), the brake boosting action of the normal brake can be sufficiently exerted at the time of engine stall.

In the brake booster according to the third aspect of the invention, the connecting portion on the negative pressure chamber side of the communication passage is provided directly in the negative pressure chamber, not in the pipe line provided with the first check valve. Therefore,
The air in the variable pressure chamber is once introduced into the negative pressure chamber and then discharged to the negative pressure source side through the pipe line and the first check valve. Therefore, the pressure reduction gradient of the master cylinder pressure increases due to the throttling effect of the pipe line, and the master cylinder pressure can be rapidly reduced.

This operation will be described with reference to FIGS. 4 and 5. As shown in FIG. 4A, when the connection portion of the communication passage on the negative pressure chamber 7 side is directly provided in the negative pressure chamber 7, when there is a pressure reduction request (see FIG. 4B). At the time point t2), when the communication control valve 3 is opened, the air from the variable pressure chamber 6 is temporarily moved to the negative pressure chamber 7
4 (b) as it is discharged to the negative pressure source side.
As indicated by the broken line, the pressure in the negative pressure chamber 7 increases rapidly.
Therefore, the pressure difference between the variable pressure chamber 6 and the negative pressure chamber 7 rapidly increases, so that the master cylinder pressure decreases steeply as shown by the solid line in FIG. 4 (c). It can be reduced quickly.

The connecting portion of the communication passage on the negative pressure chamber 7 side is shown in FIG.
As shown by the one-dot chain line in (a), when it is provided in the pipe line between the first check valve 11 and the negative pressure chamber 7, the communication control valve 3 operates when the master cylinder 9 is depressurized. Even when the air is opened, the air from the variable pressure chamber 6 branches into the negative pressure chamber 7 and the negative pressure source, and therefore, as shown by the alternate long and short dash line in FIG.
The increase in the pressure in the negative pressure chamber 7 is small. Therefore, since the pressure difference between the variable pressure chamber 6 and the negative pressure chamber 7 is small, as shown by the alternate long and short dash line in FIG. do not do.

In the brake booster according to a fourth aspect of the present invention, for example, in the communication passage, a second check valve that opens in parallel with the communication control valve when the pressure on the negative pressure chamber side is higher than the pressure on the variable pressure chamber side is provided. I have it. Therefore, even if the pressure in the negative pressure chamber is high, the air in the negative pressure chamber is supplied to the variable pressure chamber side via the second check valve, so that the pressure in the negative pressure chamber is equal to the pressure in the variable pressure chamber. It is prevented from becoming higher. As a result, it is possible to prevent the reliability of the diaphragm inside the booster from being lowered due to the internal pressure of the booster being reversed when the brake pedal is depressed.

As the brake booster of the fifth aspect, a brake booster used for adjusting the pressure of the master cylinder during the anti-skid control can be mentioned. Therefore, the claim 1
In the brake booster No. 4 described above, for example, when there is a pressure reduction request for the master cylinder during anti-skid control, for example, the communication control valve is set (for example, turned on and set to the open state).
While controlling to the communication side, the ventilation control valve (for example, OF
Since the introduction of air into the variable pressure chamber is blocked and the outflow of air from the variable pressure chamber side to the negative pressure chamber side is permitted by controlling to the shut-off side (by setting F to the closed state), it has been described above. As described above, the master cylinder pressure can be rapidly reduced, and the brake boosting action at the time of engine stall can be exhibited.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a brake booster according to the present invention will be described below in detail with reference to the drawings using examples (embodiments). (Embodiment 1) a) FIG. 5 is a schematic configuration diagram of a vehicle brake booster that performs anti-skid control and its peripheral configuration.

As shown in FIG. 5, a tandem type master cylinder 9 is connected to the brake booster 12.
The master cylinder 9 is connected to a hydraulic control circuit 15 for anti-skid control, which is composed of two hydraulic systems of X piping (diagonal piping).

The brake booster 12 includes the engine 1
The negative pressure (intake negative pressure) of the intake manifold generated at 9 and the atmospheric pressure are used to adjust the pressure difference as the brake pedal 5 is depressed, and the piston of the master cylinder 9 (not shown) is adjusted. It exerts a so-called boosting action that increases the force applied to.

This brake booster 12 is provided with a variable pressure chamber 6 and a negative pressure chamber 7 which are partitioned by a diaphragm 21, and a first mechanical valve for adjusting the pressure in both chambers 6 and 7. First and second mechanical valves 2, a communication control valve 3 and a ventilation control valve 4 are provided. Of these, the first and second mechanical valves 1 and 2 are mechanically opened and closed according to the operation of the push rod 5a of the brake pedal 5, and when the brake pedal 5 is depressed, the first mechanical valve 1 is closed and the second mechanical valve 2 is open. Further, the communication control valve 3 and the ventilation control valve 4
Is an electronic control unit (E
CU; see FIG. 6).
It is a solenoid valve driven to a position.

The communication control valve 3 includes a variable pressure chamber 6 and a negative pressure chamber 7.
Is provided in a communication passage 23 that communicates with the control passage 3. The communication passage 23 is opened in parallel with the communication control valve 3 when the negative pressure chamber 7 side is higher in pressure than the variable pressure chamber 6 side. A second check valve 25 is provided to allow the gas to escape to the chamber 6 side. The connecting portion 23a of the communication passage 23 on the negative pressure chamber 7 side is directly connected to the negative pressure chamber 7. On the other hand, the ventilation control valve 4 is provided in the variable pressure chamber 6
Is provided in the ventilation passage 27 for introducing the atmosphere, which is connected to the second mechanical valve 2 via the second mechanical valve 2.

A first check valve, which is opened when the pressure on the intake side of the engine 19 becomes lower than the pressure on the negative pressure chamber 7 side, is provided in a pipe line 29 connecting the engine 19 and the negative pressure chamber 7. 11 is provided. Therefore, when the engine stalls, the pressure on the intake side rises toward the atmospheric pressure and the negative pressure chamber 7
When the pressure becomes higher than the pressure on the side, the first check valve 11 is closed.

The master cylinder 9 has a first hydraulic pressure port 31 and a second hydraulic pressure port 33, of which the first hydraulic pressure port 31 passes through a first hydraulic pressure pipe 35 and is a wheel of the front right (FR) wheel. The cylinder (W / C) 37 and the wheel cylinder 38 of the left rear (RL) wheel are in communication with each other. The second hydraulic port 33 has a second hydraulic pipe 36.
After that, the wheel cylinder 39 for the right rear (RR) wheel and the wheel cylinder 40 for the left front (FL) wheel are communicated with each other.

In the first hydraulic pipe 35, a FR side first hydraulic control valve 41 and a FR side second hydraulic control valve 42 for controlling the hydraulic pressure of the FR wheel wheel cylinder 37, and an RL wheel wheel cylinder 38. An RL side first hydraulic control valve 43 and an RL side second hydraulic control valve 44 for controlling the hydraulic pressure are provided. The first hydraulic pipe 35 has a first reservoir 51 for releasing the brake fluid from the wheel cylinders 37 and 38, and a first reservoir 51 for releasing the brake fluid to the master cylinder 9 side when the pressure on the master cylinder 9 side decreases. 3 check valves 53 are provided.

On the other hand, in the second hydraulic pipe 36, an RR side first hydraulic control valve 45 and an RR side second hydraulic control valve 46 for controlling the hydraulic pressure of the wheel cylinder 39 of the RR wheel,
FL-side first hydraulic control valve 47 and FL-side second hydraulic control valve 4 for controlling the hydraulic pressure of the wheel cylinder 40 of the FL wheel.
And 8 are provided. In addition, the second hydraulic pipe 36 is provided with a second reservoir 52 in the same manner as the first hydraulic pipe 35.
And a fourth check valve 55 is provided.

Incidentally, as shown in FIG. 6, the brake booster 1
The ECU 24 that controls the CPU 2 and the like is a well-known CPU 24a, R
Signals from a wheel speed sensor 75 and a brake switch 79, which are mainly configured by a microcomputer including an OM 24b, a RAM 24c, an input / output unit 24d, a bus line 24e and the like, are input to the ECU 24. Then, for example, based on the input signal from each wheel speed sensor 75, the actuators such as the communication control valve 3, the ventilation control valve 4, and the hydraulic control valves 41 to 48 are drive-controlled,
Performs anti-skid control, etc.

B) Next, the basic operation of the brake booster 12 will be briefly described. When exerting boosting action When exerting boosting action (state of FIG. 1 (a)),
The communication control valve 3 is set to the shutoff position, and the ventilation control valve 4 is set to the communication position.

In this case, the engine 19 is installed in the negative pressure chamber 7.
In addition to the intake negative pressure acting on the variable pressure chamber 6 and the atmospheric pressure acting on the variable pressure chamber 6, the brake booster 12 operates by depressing the brake pedal 5 in accordance with the pressure difference between the intake negative pressure and the atmospheric pressure. The force applied to the master cylinder 9 is boosted.

As a result, the hydraulic pressure generated by the master cylinder 9 greatly increases, so the wheel cylinder pressure also greatly increases, and the braking force also greatly increases. When the boosting action is not exerted When the boosting action is not exerted (the state of FIG. 1B), the communication control valve 3 is set to the communication position and the ventilation control valve 4 is set to the cutoff position.

In this case, since the negative pressure chamber 7 and the variable pressure chamber 6 are communicated with each other, the pressure difference as described above does not occur. Therefore, the force applied to the master cylinder 9 by the depression operation of the brake pedal 5 is not boosted. As a result, the hydraulic pressure generated by the master cylinder 9 does not increase so much, so the wheel cylinder pressure does not increase significantly, and therefore the braking force does not increase significantly.

C) Next, the overall operation of the brake booster of this embodiment will be described with reference to FIG. First, as shown in FIG. 7, at time t1, the brake pedal 5
When is depressed, the first mechanical valve 1 is closed and the second mechanical valve 2 is opened. At this time, the communication control valve 3 is set to be closed and the ventilation control valve 4 is set to be open. Therefore, the pressure in the variable pressure chamber 6 increases rapidly, but the pressure in the negative pressure chamber 7 does not change, and therefore the pressure difference between the two chambers 6 and 7 increases, so that a brake boosting action during normal braking is exerted. be able to.

Next, at time t2, when the anti-skid control is started and the master cylinder 9 is requested to be depressurized in order to reduce the wheel cylinder pressure (wheel cylinder pressure) and reduce the slip, the communication control is performed. The valve 3 is opened and the ventilation control valve 4 is closed. As a result, the pressure in the variable pressure chamber 6 rapidly decreases, and the pressure in the negative pressure chamber 7 once rapidly increases and then decreases similarly to the pressure in the variable pressure chamber 6. As a result, the pressure difference between the two chambers 6 and 7 is rapidly reduced, so that the master cylinder pressure is rapidly reduced.

Next, at time t4, when there is a pressure increase request of the master cylinder 9 in order to increase the wheel cylinder pressure in the anti-skid control, the communication control valve 3 is closed and the ventilation control valve 4 is opened. To As a result, the pressure in the negative pressure chamber 7 does not change so much, but the pressure in the variable pressure chamber 6 increases rapidly. As a result, the pressure difference between the two chambers 6 and 7 increases rapidly, and the master cylinder pressure increases rapidly.

D) In this way, in this embodiment, the ECU 24
Since the communication control valve 3 and the ventilation control valve 4 controlled by the master cylinder 9 are provided, when the master cylinder 9 is decompressed, the communication control valve 3 is closed and the ventilation control valve 4 is opened. The cylinder pressure can be quickly reduced. Therefore, the hydraulic control valve 41 during anti-skid control
It is possible to reduce the operating noise such as 48, and also to reduce the kickback of the brake pedal 5.

When the pressure on the intake side of the engine 19 becomes lower than the pressure in the negative pressure chamber 7, the first check valve 11 for shutting off the conduit 29 is provided. However, the pressure in the negative pressure chamber 7 can be maintained at a certain negative pressure as shown in FIG. As a result, even when the engine is stalled, it is possible to exert a brake boosting action during normal braking.

Further, the connecting portion 2 of the communication passage 23 on the negative pressure chamber 7 side.
Since 3a is directly connected to the negative pressure chamber 7, as shown in FIG. 4, when there is a pressure reduction request for the master cylinder 9, the pressure reduction gradient of the master cylinder 9 can be increased. Therefore, the master cylinder pressure can be quickly reduced.

In addition, since the communication path 23 is provided with the second check valve 25 in parallel with the communication control valve 3, the pressure on the negative pressure chamber 7 side becomes higher than the pressure on the variable pressure chamber 6 side. In that case, the pressure can be released to the variable pressure chamber 6 side.
As a result, the pressure on the negative pressure chamber 7 side can always be set lower than the pressure on the variable pressure chamber 6 side.
It is possible to prevent the reliability of the diaphragm 21 in the brake booster 12 from being lowered due to the reversal of the internal pressures of the two chambers 6 and 7 when the vehicle is depressed. (Embodiment 2) Next, Embodiment 2 will be described. The brake booster of this embodiment is slightly different from that of Embodiment 1 in the structure of the duct for ventilation. The description of the same parts as in the first embodiment will be omitted or simplified.

As shown in FIG. 8, the brake booster 100 of this embodiment is provided with a communication control valve 107 in a communication passage 105 that connects the variable pressure chamber 101 and the negative pressure chamber 103, and
A ventilation control valve 111 is provided in a ventilation path 109 for introducing the atmosphere into the variable pressure chamber 101. Further, the ventilation passage 109 and the communication passage 1
05 is connected to the transformer room 101 side. That is, the pipeline 101a connected to the variable pressure chamber 101 side is branched midway and connected to the communication control valve 107 and the ventilation control valve 111.

This structure also has the same effects as those of the first embodiment, and has the advantage that the structure is simplified because the length of the conduit is short. In this embodiment,
Depending on how the brake pedal 102 is depressed, the second mechanical valve 104 may be closed at the initial stage of depression. In that case, the air in the pipe line 101a flows into the negative pressure chamber 103, so that both chambers 101 are closed. , 103 reduces the pressure difference, and the structure of the brake booster 100 accordingly increases the second mechanical valve 104.
There will be no problem as it opens. (Third Embodiment) Next, a third embodiment will be described. The brake booster of this embodiment is slightly different from the first embodiment in the structure of the communication control valve. The description of the same parts as in the first embodiment will be omitted or simplified.

As shown in FIG. 9, the brake booster 120 of this embodiment is provided with a communication control valve 127 in a communication passage 125 which connects the variable pressure chamber 121 and the negative pressure chamber 123.
A ventilation control valve 131 is provided in a ventilation path 129 that introduces air into the variable pressure chamber 121. In particular, in this embodiment, the communication control valve 127 is provided inside with a portion 127a for opening the conduit and a portion 127b also having the function of the second check valve. Therefore, every time the communication control valve 127 is turned on / off,
The pipeline is switched between an open state and an open state when the pressure in the negative pressure chamber 123 is higher than that in the variable pressure chamber 121.

This structure also has the same effect as that of the first embodiment, and has the advantage that the structure is simplified because it is not necessary to provide a conduit in parallel with the communication control valve 127. It is needless to say that the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the technical scope of the present invention.

(1) In addition to the hydraulic control circuit of the first embodiment, for example, a hydraulic control circuit as shown in FIG. 10 can be adopted. For example, the hydraulic control circuit of FIG. 10 (a) has one hydraulic control valve arranged in each wheel cylinder, and the hydraulic control circuit of FIG. 10 (b) has the same configuration as that of the first embodiment. A pump for sucking the brake fluid from the reservoir to the master cylinder side is arranged.

(2) Also, the effectiveness of the brake booster is adjusted by adjusting the open / closed state of the communication control valve or the ventilation control valve or the state of the opening thereof, for example, by changing the duty ratio. be able to. For example, by setting the duty ratio so that the opening period of the ventilation control valve during normal braking becomes shorter as the number of passengers decreases, the degree of pressure increase in the variable pressure chamber decreases, thus reducing the brake boosting effect. Can be made. This makes it possible to obtain the same deceleration with the same pedaling force without being affected by the change in the number of passengers.

The same applies to the case of anti-skid control, and when the number of passengers increases and the weight of the vehicle increases, the brake boosting action is adjusted by adjusting the change in the weight. Stable anti-skid control can be performed. For example, when anti-skid control is performed when the weight increases, the brake boosting action needs to be made larger (compared to when the weight is lighter). Adjust the duty ratio of the valve.

(3) In the first embodiment, the brake booster utilizing the engine negative pressure and the atmospheric pressure is taken as an example, but the brake booster may be, for example, an accumulator or the like. The one using the pressure source of can be adopted.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating the configuration of a brake booster according to the first aspect of the invention.

FIG. 2 shows the action of the brake booster according to the invention of claim 1, (a) is a graph showing the internal pressure of the booster, and (b) is a graph.
Is a graph showing the master cylinder pressure.

FIG. 3 shows the action of the brake booster of the invention of claim 2, (a) is a graph showing the booster internal pressure, (b)
Is a graph showing the master cylinder pressure.

FIG. 4 shows a brake booster according to the invention of claim 3,
(A) is explanatory drawing which illustrates the structure, (b) is a graph which shows the booster internal pressure, (c) is a graph which shows the master cylinder pressure.

FIG. 5 is a schematic configuration diagram showing a brake booster of Example 1 and its peripheral configuration.

FIG. 6 is a block diagram showing a configuration of an electronic control device according to a first embodiment.

FIG. 7 is an explanatory diagram showing an operation of the brake booster according to the first embodiment.

FIG. 8 is a schematic configuration diagram illustrating a brake booster according to a second embodiment and a peripheral configuration thereof.

FIG. 9 is a schematic configuration diagram showing a brake booster and its peripheral configuration according to a third embodiment.

FIG. 10 is a circuit diagram showing another hydraulic control circuit.

[Explanation of symbols]

 3, 107, 127 ... Communication control valve 4, 111, 131 ... Ventilation control valve 5, 102 ... Brake pedal 9 ... Master cylinder 11 ... First check valve 12, 100, 120 ... Brake booster 15 ... Hydraulic control circuit 19 ... Engine 23,105,125 ... Communication passage 23a ... Connection part 25 ... Second check valve 27,109,129 ... Ventilation passage 37,38,39,40 ... Wheel cylinder

Claims (5)

[Claims] 1. A negative pressure chamber into which a negative pressure is introduced from a negative pressure source,
A variable pressure chamber in which ventilation is performed from a pressure source that is higher than the negative pressure source, and a braking force applied to the brake fluid on the master cylinder side by multiplying the acting force applied to the brake pedal by the driver's brake operation. In the force device, a communication control valve that is provided in a communication passage that communicates between the negative pressure chamber side and the variable pressure chamber side and that controls the opening and closing of the communication passage according to a command signal during vehicle control; And a ventilation control valve which is provided on a side of the ventilation passage for performing ventilation from the pressure source and which controls the opening and closing of the ventilation passage in response to a command signal during vehicle control. apparatus. 2. The negative pressure chamber side connection portion of the communication passage is located closer to the negative pressure chamber side than the first check valve that opens when the pressure on the negative pressure source side is lower than the pressure on the negative pressure chamber side. The brake booster according to claim 1, wherein the brake booster is provided. 3. The brake booster according to claim 2, wherein the connection portion of the communication passage on the negative pressure chamber side is provided directly on the negative pressure chamber. 4. The second check valve, which is opened in parallel with the communication control valve when the pressure on the negative pressure chamber side is higher than the pressure on the variable pressure chamber side, is provided. ~
The brake booster according to any one of 3 above. 5. A brake booster according to any one of claims 1 to 4, wherein the brake booster is used for adjusting the pressure of a master cylinder during anti-skid control.