JPH09226553A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress brake fluid accumulation within a reservoir by implementing pressure reducing control of a wheel cylinder via a pressure control means and by reducing boosting function of a brake boosting means in the case of being requested for reducing wheel cylinder pressure. SOLUTION: In the case deceleration of a wheel, for example a FR wheel, exceeds the second standard, a vacuum pressure control valve 23 is set to open position and an atmospheric pressure selector valve 29 is set to closed position so that the pressure differences with cylinders 13, 15 is reduced for reducing boosting function of a brake booster 5. At this time, the FR wheel is excepted from the object of boosting control and the brake booster 5 is operated based on a request from other wheels. At this stage, in order to control the hydraulic pressure of within the wheel cylinder 37 for the FR wheel, fluid pressure control valve 41 is set to closed position and fluid pressure control valve 42 is set to open position for discharging brake fluid within the wheel cylinder 37 and thereby to relieve the FR wheel of its locked condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for performing, for example, antiskid control.

[0002]

2. Description of the Related Art Conventionally, for example, in a brake control device for performing anti-skid control, an anti-skid control is performed by controlling a hydraulic control valve and a motor pump provided in a brake pipe to adjust a master cylinder pressure and the like. I was doing.

Specifically, as shown in FIG. 13 (a), a predetermined slip state (S) in which wheel lock occurs during wheel braking.
1, S2, S3, etc.), for example, by controlling the hydraulic control valve, the brake fluid (fluid) in the wheel cylinder
Is released to the reservoir to perform pressure reduction control to reduce the wheel cylinder pressure, thereby reducing the braking force applied to the wheels and releasing the locked state, resulting in an appropriate slip state with high braking ability. It is in control. Further, the master cylinder pressure is re-pressurized by returning the brake fluid in the reservoir to the master cylinder side by the motor pump.

Further, as another technique, a so-called brake booster for doubling the depression force of the brake pedal is attached to the vehicle in order to ensure the driver's brake operation. This brake booster increases the depression force of the brake pedal to apply a large pressure to the master cylinder side by utilizing the difference between the negative pressure on the intake side of the engine and the atmospheric pressure.

[0005]

However, the above-mentioned brake control device has the following problems and is not always preferable. When the anti-skid control is performed, the brake fluid accumulates in the reservoir every time the pressure reduction control is performed, but if the master cylinder pressure is higher than necessary, there is a problem that the amount of the brake fluid accumulated in the reservoir during the pressure reduction control increases. .

The present invention has been made in view of the above problems, and an object of the present invention is to provide a brake control device that suppresses the amount of brake fluid accumulated in a reservoir.

[0007]

In the brake control device according to the first aspect of the present invention, the brake boosting means boosts the pressure applied by the braking operation of the driver to apply it to the master cylinder side, and is provided in the brake pipe. For example, the pressure (wheel cylinder pressure; W / C pressure) of the wheel cylinder that suppresses wheel rotation is adjusted to increase or decrease by pressure adjusting means such as a hydraulic control valve and a reservoir. When there is a demand for reducing the wheel cylinder pressure, the brake boosting control means reduces the boosting action of the brake boosting means (for example, to off). Further, the pressure control means controls the operation of the pressure adjusting means to control the reduction of the wheel cylinder pressure.

That is, in the present invention, when there is a demand for reducing the wheel cylinder pressure, not only the pressure control means performs the pressure reduction control of the wheel cylinder pressure but also the boosting action of the brake boosting means is reduced. . This suppresses an excessive increase in the master cylinder pressure (M / C pressure) even when the brake pedal is depressed more than necessary, and thus suppresses an excessive increase in the wheel cylinder pressure. As a result, for example, in the pressure reduction control of the wheel cylinder pressure, the amount of brake fluid accumulated in the reservoir from the wheel cylinder can be suppressed.

Further, since the difference between the master cylinder pressure and the wheel cylinder pressure is small, the pulsation at the time of pulse pressure increase when anti-skid control is performed becomes small (see FIG. 5).
(Refer to W / C pressure in (b)) Therefore, there is an advantage that pulsating sound at the time of pulse pressure increase can be reduced and finer control can be performed.

Moreover, since the master cylinder pressure can be reduced, the force for pushing back the brake pedal can be reduced, and
There is also an effect that the pedal feeling is improved. In the brake control device according to the second aspect, for example, anti-skid control for optimally controlling the slip state during wheel braking to improve braking performance is performed. In addition, the brake boosting control means reduces the boosting action of the brake boosting means. If the wheel slip state is not improved by this boosting action, the pressure control means drives and controls the pressure adjusting means to control the wheel cylinder pressure.

That is, in the present invention, the master cylinder pressure is reduced by reducing the boosting action of the brake boosting means before the conventional anti-skid control is performed using the hydraulic control valve or the like. By reducing the boosting action of the brake boosting means, the slip state of the wheels can be improved, and as a result, the number of times of operation of the motor pump can be reduced, and thus the operating noise and vibration can be reduced.

Further, since the pulsation at the time of pulse pressure increase in the case of performing the anti-skid control becomes small, the pulsating sound at the time of pulse pressure increase can be reduced and finer control can be performed. In addition, the pedal feeling is improved. In the brake control device according to the third aspect of the invention, when the wheel cylinder pressure is controlled by the pressure control means for all the wheels, the master cylinder pressure is considerably large relative to the wheel cylinder pressure for all the wheels (predetermined value). When it becomes larger than the value), the brake boosting control means controls to reduce the boosting action of the brake boosting means.

That is, even when the wheel cylinder pressure is controlled by the pressure control means, when the master cylinder pressure is too high, the control for reducing the boosting action of the brake boosting means by the brake boosting control means. Therefore, it is possible to suppress the increase of the master cylinder pressure and reduce the above-described operating noise and vibration of the motor pump.

According to another aspect of the brake control device of the present invention, when the wheel cylinder pressure is controlled by the pressure control means for all the wheels, the brake is applied according to the slip state of the wheel having the highest wheel cylinder pressure. The boosting control means controls increase / decrease of the boosting action of the brake boosting means.

That is, even when the wheel cylinder pressure is controlled by the pressure control means, the boosting action of the brake boosting means can be increased / decreased by the brake boosting control means. Excessive pressure increase can be suppressed to reduce the above-described operating noise and vibration of the motor pump.

In the brake control device according to the fifth aspect, when the wheel cylinder pressure is controlled by the pressure control means for all the wheels, there are a plurality of wheels in which the master cylinder pressure and the wheel cylinder pressure are close to each other. Sometimes
The boosting action of the brake boosting means is increased or decreased according to the slip state of the plurality of wheels.

That is, in such a pressure state, it is more effective to control the wheel cylinder pressure depending on the slip states of a plurality of wheels than to control the slip state of a single wheel. There is an advantage that pressure shortage can be prevented and control stability is improved.

In the brake control device according to the sixth aspect of the present invention, since the boosting action of the brake boosting means is increased or decreased according to the weighted average value of the slip states of the plurality of wheels, the processing can be simplified. In the brake control device according to the seventh aspect, since the boosting function of the brake boosting means is used by being turned on / off by, for example, a solenoid valve, the structure can be simplified.

According to the brake control device of claims 8 and 9,
It comprises a pressure source for generating a gas pressure and a master cylinder for generating a fluid pressure, the first adjusting means adjusts the magnitude of the gas pressure, and the second adjusting means adjusts the magnitude of the fluid pressure. As described above, since the configuration for adjusting both the gas pressure and the fluid pressure is provided, the range of methods for controlling the wheel braking force generated in the wheel cylinder is widened. That is, the first adjusting means adjusts the gas pressure which is the base pressure for generating the fluid pressure applied to the wheel cylinder, and the second adjusting means adjusts the fluid pressure formed by the base pressure.
A two-step pressure regulation is feasible.

If there are a plurality of wheel cylinders that receive the fluid pressure from the master cylinder, and the second adjusting means is configured so that the amount of pressurization of the fluid pressure applied to each wheel cylinder can be adjusted independently, In order to adjust the gas pressure, which is the base pressure for generating the fluid pressure applied to each wheel cylinder, by the first adjusting means, and to adjust the fluid pressure applied to each wheel cylinder by the second adjusting means,
The wheel braking force generated in each wheel cylinder can be adjusted in two stages.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of a brake control device of the present invention will be described in detail with reference to the drawings by way of examples (embodiments). (Embodiment 1) a) FIG. 1 is a hydraulic circuit diagram schematically showing a brake control device for an automobile which performs anti-skid control.

As shown in FIG. 1, the brake control apparatus of this embodiment is provided with a hydraulic control circuit 1 for anti-skid control, which is composed of two hydraulic systems of X piping (diagonal piping). A brake booster (brake booster) 5 that boosts the depression force of the brake pedal 3 is connected to the circuit 1 by a tandem master cylinder 7.

The brake booster 5 utilizes the pressure difference between the negative pressure of the intake manifold (intake negative pressure) generated in the engine 9 and the atmospheric pressure, and uses the brake pedal 3
The pressure difference is adjusted in accordance with the depression of, and the so-called boosting action of increasing the force applied to the piston (not shown) of the master cylinder 7 is exhibited.

Specifically, the brake booster 5 is formed with a first power cylinder 13 and a second power cylinder 15 which are partitioned by a diaphragm 11. This first
Also, the negative pressure port 1 is provided on the second power cylinders 13 and 15.
The intake negative pressure of the engine 9 is introduced through 7, 19 and the negative pressure level of the second power cylinder 15 is the negative pressure control valve 23 which is an electromagnetic two-position control valve.
It is controlled according to the communication / interruption operation of.

The negative pressure control valve 23 is an electronic control unit 25.
Its position is controlled by (see FIG. 2; hereinafter referred to as ECU), but when there is no input signal from the ECU 25 (when the coil is not excited), the negative pressure control valve 23 is held at the shut-off position (illustrated). State). Further, atmospheric pressure is introduced into the second power cylinder 15 through the atmospheric pressure port 27. At this time, the atmospheric pressure is adjusted by a pressure adjusting valve (not shown) according to the depression of the brake pedal 3 and is introduced into the second power cylinder 15. Therefore, the second power cylinder 15 produces a large pressure difference with respect to the first power cylinder 13.

The atmospheric pressure port 27 is opened and closed by an electromagnetic type 2.
It is controlled by the atmospheric pressure control valve 29 which is a position control valve,
The atmospheric pressure control valve 29 is held in the communicating position (state shown) when there is no input signal from the ECU 25 (when the coil is not excited). Further, the master cylinder 7 is
It has a first hydraulic port 31 and a second hydraulic port 33, of which the first hydraulic port 31 passes through a first hydraulic pipe 35 and has a wheel cylinder 37 of a front right (FR) wheel and a rear left (RL) wheel. Of the wheel cylinder 38. In addition, the second hydraulic port 33 has a second hydraulic pipe 3
After 6, 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.

The first hydraulic pipe 35 is provided with a first FR side for controlling the hydraulic pressure of the wheel cylinder 37 of the FR wheel.
Hydraulic control valve 41 and second hydraulic control valve 42 on the FR side,
An RL-side first hydraulic control valve 43 and an RL-side second hydraulic control valve 44 for controlling the hydraulic pressure of the wheel cylinder 38 of the RL wheel are provided. Further, in the first hydraulic pipe 35, a reservoir 51 for releasing the brake fluid from the wheel cylinders 37 and 38, and a check valve 53 for releasing the brake fluid to the master cylinder 7 side when the reservoir 51 side has a predetermined pressure or more. Is provided.

On the other hand, the RR is connected to the second hydraulic pipe 36.
RR for controlling the hydraulic pressure of the wheel cylinder 39 of the wheel
Side first hydraulic control valve 45 and RR side second hydraulic control valve 4
6 and an FL-side first hydraulic control valve 47 and an FL-side second hydraulic control valve 48 for controlling the hydraulic pressure of the wheel cylinder 40 of the FL wheel. Further, the second hydraulic pipe 36 is provided with a reservoir 52 and a check valve 55, like the first hydraulic pipe 35.

Further, wheel speed sensors 75, 76, 77 and 78 for detecting the wheel speeds of the respective wheels are provided on the respective wheels, and the respective sensor signals are inputted to the ECU 25.
As the wheel speed sensors 75 to 78, electromagnetic pickup type sensors or photoelectric conversion type sensors are used. Further, the brake pedal 3 is provided with a brake switch 79 for detecting the presence / absence of a pedal depression operation, and the detection signal thereof is input to the ECU 25.

The ECU 25, as shown in FIG.
PU 25a, ROM 25b, RAM 25c, input / output unit 2
5d, a bus line 25e, and the like are mainly configured, and the input / output unit 25d is connected to the brake switch 79 and the wheel speed sensors 75 to 78 as a sensor, and as an actuator. The negative pressure control valve 23, the atmospheric pressure control valve 29, the hydraulic pressure control valves 41 to 48, etc. are connected via a drive circuit (not shown).

As will be described later in detail, the ECU 25 calculates the estimated vehicle body speed based on the input signals from the wheel speed sensors 75 to 78, obtains the slip ratio from the estimated vehicle body speed and the wheel speed, The lock tendency of each wheel is determined from the slip ratio and the wheel acceleration, and each actuator is drive-controlled to perform anti-skid control.

B) Next, the operation of the brake booster 5 will be briefly described. When exerting boosting action (brake booster 5; O
N) When the boosting action is exerted (state of FIG. 1), the negative pressure control valve 23 is set to the shutoff position and the atmospheric pressure control valve 29 is set to the communication position.

In this case, the intake negative pressure from the engine 9 acts on the first power cylinder 13, and
Since the atmospheric pressure acts on the second power cylinder 15, the brake booster 5 boosts the force applied to the master cylinder 7 by depressing the brake pedal 3 in accordance with the pressure difference between the intake negative pressure and the atmospheric pressure. .

As a result, the hydraulic pressure generated by the master cylinder 7 is greatly increased, so that the wheel cylinder pressure is also greatly increased and the braking force is greatly increased. When not exerting a boosting effect (brake booster 5;
OFF) When the boosting action is not exerted (state of FIG. 7), the negative pressure control valve 23 is set to the communication position and the atmospheric pressure control valve 29 is set to the cutoff position.

In this case, since the first and second power cylinders 13 and 15 are communicated with each other, the pressure difference as described above does not occur. Therefore, the force applied to the master cylinder 7 by depressing the brake pedal 3 is not boosted. As a result, the hydraulic pressure generated by the master cylinder 7 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 procedure for starting the anti-skid control of the brake control system of this embodiment will be described with reference to FIGS. First, the main routine for starting the anti-skid control will be described based on the flowchart of FIG.

In step 100 of FIG. 3, the wheel speed Vw of each wheel is calculated based on the signals from the wheel speed sensors 75 to 78. In the following step 110, by obtaining the speed change of each wheel speed Vw per unit time,
Each wheel acceleration Gw is calculated.

In the following step 120, the estimated vehicle body speed Vs is obtained by applying a predetermined guard, for example, based on the maximum one of the wheel speeds Vw. Continued Step 130
Then, based on the estimated vehicle body speed Vs and each wheel speed Vw, the slip ratio S is calculated for each wheel from the following equation (1).

S = (Vs-Vw) / Vs (1) In the following step 140, antiskid control is performed based on the slip ratio S, the wheel acceleration Gw, etc., as will be described later, and then step 100 is executed. Return. Next, the specific anti-skid control processing in step 140 will be described in detail with reference to the flowchart of FIG. 4 and the explanatory views of FIGS.

The anti-skid control of this embodiment is shown in FIG.
As shown in (a), it is composed of control by the brake booster 5 when the locked state of the wheel is small (phase I) and control by the hydraulic control circuit 1 when the locked state is large (phase II). In the normal traveling state, the brake booster 5 is in the above-mentioned ON state, that is, in a state capable of performing a boosting action.

First, in step 200 of FIG. 4, it is determined whether the brake switch 79 is on, that is, whether the brake pedal 3 is depressed. Here, if an affirmative judgment is made, the routine proceeds to step 210, while if a negative judgment is made, this processing is once terminated. In step 210, it is determined whether or not the slip ratio S of the wheel to be controlled is a predetermined value or more, that is, whether or not anti-skid control should be performed. Here, if an affirmative decision is made, the routine proceeds to step 220,
On the other hand, if a negative decision is made, this processing is once terminated.

In step 220, it is determined whether the wheel acceleration Gw satisfies the first standard, that is, whether the degree of deceleration of the wheel is larger than the first standard. Here, if an affirmative judgment is made, the routine proceeds to step 230, while if a negative judgment is made, this processing is once terminated.

That is, here, it is judged whether or not the antiskid control is finally performed. If the wheels are decelerating beyond the first reference, the antiskid control is performed in the subsequent steps. On the other hand, when the degree of wheel deceleration is not so great, the anti-skid control is not executed yet.

In step 230, since the degree of deceleration of the wheels exceeds the first standard, the brake booster 5 is set to the off state. That is, since the wheel lock state has exceeded the reference state, as described above, the negative pressure control valve 23
And the atmospheric pressure control valve 29, that is, the negative pressure control valve 23.
To the communicating position and the atmospheric pressure control valve 29 to the shutoff position,
Controls to stop the boosting action.

Up to this point, the control has been performed in the above-mentioned period I, and as a result, the master cylinder pressure decreases, so the wheel cylinder pressure also decreases, and therefore the braking force also decreases. Therefore, when the degree of locking of the wheels is not so great, the locked state can be released only by this processing.

In the following step 240, the wheel acceleration Gw
Satisfies the second criterion, that is, whether the degree of deceleration of the wheels is larger than the second criterion (above the first criterion value). Here, if the affirmative judgment is made, the routine proceeds to step 250, while if the negative judgment is made, the step 29 is carried out.
Go to 0.

That is, here, it is determined whether or not the strong anti-skid control by the hydraulic control circuit 1 is performed, and when the degree of deceleration of the wheels is larger than the second reference, that is, when the degree of locking is large. In the following steps, the anti-skid control by the hydraulic control circuit 1 is executed, and when the degree of deceleration of the wheels is equal to or less than the second reference, the anti-skid control by the hydraulic control circuit 1 is not executed.

In step 290, in order to avoid an abrupt change of the control state and unnecessary reduction of the boosting action, the brake booster 5 is turned on to restore the boosting action after waiting for a predetermined time. This process ends. On the other hand, in step 250, a process of removing the wheel from the target for controlling the brake booster 5 is performed.

In the following step 260, the well-known anti-skid control by the hydraulic control circuit 1 is performed on the wheel which is excluded from the control target of the brake booster 5. In other words, the case where the process proceeds to the above-mentioned step 230.
In this case, the wheel lock state is not improved and the wheel deceleration is in a larger state even by the control for stopping the boosting action of the brake booster 5 in (1). 41-48 and reservoir 5
The anti-skid control of the II phase by 1, 52 etc. is performed.

Specifically, as shown in FIG. 6 (only showing the control of the hydraulic control circuit 1), the slip ratio S and the wheel acceleration G are shown.
According to w, the control mode of the wheel cylinder pressure is switched to the pressure increasing mode, the holding mode, and the pressure reducing mode, and the well-known anti-skid control with the desired slip ratio S is performed.

In the following step 270, it is determined whether or not all the wheels of the vehicle that have been weighted and selected (that is, the wheels that have been selected and controlled in step 250) have entered the anti-skid control by hydraulic control. To do. If an affirmative judgment is made here, the routine proceeds to step 280, while if a negative judgment is made, this processing is once terminated.

In step 280, the brake booster 5 is turned on / off according to the state of the selected wheel, thereby performing the stop / recovery control of the boosting control, and the present processing is ended. d) Next, the state of the anti-skid control in each step described above will be described more specifically with reference to the explanatory views of FIGS. 7 to 9.

In step 220, when the deceleration state of a wheel (for example, FR wheel) exceeds the first reference, the brake booster 5 is turned off in step 230. The state is shown in FIG. In this case, the negative pressure control valve 23 is set to the communication position and the atmospheric pressure control valve 29 is set to the cutoff position. Therefore, the pressure difference between the first power cylinder 13 and the second power cylinder 15 is reduced, and the boosting action of the brake booster 5 is reduced.

At this stage, the anti-skid control for driving the hydraulic pressure control valves 41 to 48 and the like by the hydraulic pressure control circuit 1 is not executed, so that the master cylinder 7 is used for all four wheels.
And the wheel cylinders 37 to 40 are in communication with each other, and the hydraulic control circuit 1 is the same as that shown in FIG.

Therefore, by the control for stopping the boosting action of the brake booster 5, the lock can be released when the degree of lock of the wheels is small. In step 240, a wheel (for example, FR wheel)
When the deceleration state of No. 2 exceeds the second reference, the anti-skid control by the hydraulic control circuit 1 is performed at step 260. The state of the brake control device in that case is shown in FIG.

In this case, as in the case of FIG. 7, the negative pressure control valve 23 is set to the communicating position and the atmospheric pressure control valve 29 is set to the blocking position. Therefore, the pressure difference between the first power cylinder 13 and the second power cylinder 15 is reduced, and the boosting action of the brake booster 5 is reduced. At this time, in FIG. 8, the negative pressure control valve 23 and the atmospheric pressure control valve 29 are drawn at positions where the boosting action is stopped, but in step 250 of FIG. 4, the FR wheel is boosted. Since it is out of the control target of the control, the brake booster 5 is driven according to the request of other wheels.

At this stage, in order to perform anti-skid control by the hydraulic control circuit 1 for the FR wheel,
That is, the hydraulic pressure control valves 41 and 42 are driven to control the hydraulic pressure of the FR wheel hall cylinder 37. Specifically, in FIG. 8, the hydraulic control valve 41 is set to the shut-off position, the hydraulic control valve 42 is set to the communication position, and the brake fluid in the wheel cylinder 37 is released to the reservoir 51 (pressure reduction mode).
Is shown. More specifically, the control of the master cylinder pressure is precisely controlled in the pressure increasing mode, the holding mode, and the pressure reducing mode, and the locked state is released.

As a result, the FR wheel master cylinder 3
Since the hydraulic pressure of 7 decreases in the pressure reducing mode, the locked state of the FR wheel is released. In this case, the FR wheel is controlled by the hydraulic pressure control circuit 1, but the brake booster 5 is controlled by the next locked state, for example, RL.
It will be executed depending on the slip state of the wheels.

Further, the processing of steps 200 to 260 is repeated, and each wheel (FR wheel, RL wheel, RR wheel) is sequentially
FIG. 9 shows a state in which anti-skid control is being performed by the hydraulic circuit 1 on the wheels).
Since only the wheels are locked to a small extent, only the control by the brake booster 5 is performed.

In this case, in step 250,
Since the FR wheel, the RL wheel, and the RR wheel are excluded from the control targets of the boost control, the brake booster 5 is driven mainly in accordance with the request of the FL wheel. Further, at this stage, in order to perform anti-skid control by the hydraulic control circuit 1 for the FR wheel, the RL wheel, and the RR wheel, that is, FR wheel
The hydraulic pressure control valves 41 to 46 are driven in order to control the hydraulic pressures of the hall cylinders 37 to 39 of the wheels RL and RR.

Specifically, in FIG. 9, the hydraulic pressure control valve 41 is set to the shut-off position and the hydraulic pressure control valve 42 is set to the communication position for the FR wheel, and the brake fluid in the wheel cylinder 37 is released to the reservoir 51. (Decompression mode) is shown. For the RL wheel, the hydraulic pressure control valves 43 and 44 are set to the shut-off positions to hold the hydraulic pressure in the wheel cylinder 38 (holding mode). As for the RR wheel,
The state (holding mode) in which the hydraulic pressures inside the wheel cylinder 39 are held by setting the hydraulic pressure control valves 45 and 46 to the shutoff position is shown. The remaining FL wheels are in a state where the master cylinder 7 and the wheel cylinder 40 are in communication with each other.

As a result, the hydraulic pressure of the master cylinder 37 for the FR wheel, the RL wheel, and the RR wheel decreases in the pressure reducing mode, so that the locked state of the FR wheel, the RL wheel, and the RR wheel is released. e) In the present embodiment, the following effects are achieved by the above configuration.

In this embodiment, when the degree of locking of the wheels is small, first, the brake booster 5 is adjusted to be turned on / off to perform the anti-skid control of the I period, so that the locked state is small. Can be easily released without performing the anti-skid control by the hydraulic control circuit 1 of the second stage.

That is, when the degree of lock is small,
Since the wheel cylinder pressure can be reduced by stopping the boosting action of the brake booster 5 and lowering the master cylinder pressure, the brake fluid is released from the wheel cylinders 37 to 40 to the reservoirs 51 and 52 as in the conventional case. No need to depressurize. As a result, in a small vehicle, it is possible to eliminate the motor pump for returning the brake fluid to the master cylinder 7 side.

If the degree of lock is large,
Since the lock cannot be released only by controlling the brake booster 5, the anti-skid control is performed by the hydraulic pressure control circuit 1. Even in this case, however, the brake booster 5 should be turned off as shown in FIG. 5 (b). As a result, the difference between the master cylinder pressure and the wheel cylinder pressure does not increase, so that the amount of brake fluid released to the reservoirs 51 and 52 can be reduced.

That is, according to the present embodiment, the frequency of the wheel cylinder pressure reducing control using the reservoirs 51 and 52 can be reduced without impairing the deceleration of the vehicle in the anti-skid control. So-called reservoir bottoming, which fills up, can also be prevented.

Further, in this embodiment, since the difference between the master cylinder pressure and the wheel cylinder pressure does not become large, it is possible to reduce the pulsating sound at the time of pulse pressure increase due to the pressure difference and to finely control the wheel cylinder pressure. Can also be executed. In addition, when the brake booster 5 is turned off, the force for pushing back the brake pedal 3 does not become large, so there is an advantage that the pedal feeling is improved.

F) Next, in step 270,
The control of the brake booster 5 when the anti-skid control using the hydraulic control circuit 1 is performed on all of the preselected wheels (that is, step 280) will be described. It should be noted that here, in order to facilitate understanding, a case where all four wheels are selected wheels will be described, but in actuality, it may not be necessary to select all four wheels, depending on the traveling state.

FIG. 10 shows all wheels (FR wheel, RL wheel,
The state in which anti-skid control is performed by the hydraulic control circuit 1 for the RR wheel and the FL wheel) is shown. In FIG. 10, regarding the FR wheel, the hydraulic control valve 41 is set to the shutoff position,
The state where the hydraulic control valve 42 is set to the communicating position and the brake fluid in the wheel cylinder 37 is released to the reservoir 51 (pressure reduction mode) is shown. For the RL wheel, the hydraulic control valves 43 and 44 are set to the shutoff position and the wheel cylinder 38
The state (holding mode) in which the internal hydraulic pressure is held is shown.
Also for the RR wheel, the hydraulic pressure control valves 45 and 46 are set to the shut-off position to maintain the hydraulic pressure in the wheel cylinder 39 (holding mode). Also for the FL wheel, the hydraulic pressure control valves 47 and 48 are set to the shut-off position to hold the hydraulic pressure in the wheel cylinder 40 (holding mode).

When the wheel cylinder pressure is controlled by the hydraulic control circuit 1 for all the wheels in this way, when the master cylinder pressure becomes considerably higher than the wheel cylinder pressure in all the wheels. , The brake booster 5 controls the master cylinder pressure reduction.

That is, when the master cylinder pressure is too high, the boosting action of the brake booster 5 is stopped to suppress the excessive increase of the master cylinder pressure, and the above-mentioned reservoirs 51 and 52 are suppressed. It is possible to suppress an increase in the amount of brake fluid that accumulates in the tank, and also to prevent reservoir bottoming. Therefore, the motor pump can be eliminated in a small vehicle.

Further, when the wheel cylinder pressure is controlled by the hydraulic control circuit 1 for all the wheels, the master cylinder pressure by the brake booster 5 is changed according to the slip state of the wheel having the highest wheel cylinder pressure. The pressure increase / decrease control may be performed.

That is, the negative pressure control valve 23 and the atmospheric pressure control valve 29 are driven in accordance with the slip state of the wheel having the highest wheel cylinder pressure, that is, the wheel having a wheel cylinder pressure close to the master cylinder pressure, to drive the brake booster. The master cylinder pressure may be controlled by turning 5 on and off. The highest wheel cylinder pressure can be determined from, for example, the pressure increasing mode time.

As a result, even when the hydraulic control circuit 1 performs anti-skid control on all wheels, the brake booster 5 is controlled based on the wheel with the highest wheel cylinder pressure. Reservoir 5
In addition to suppressing the increase in the amount of brake fluid accumulated in 1,52,
The anti-skid control can be suitably performed without impairing the braking force.

When the master cylinder pressure increases, the force for pushing back the brake pedal that presses the master cylinder increases, but in this embodiment, the master is controlled by the negative pressure control (which is the control of the negative pressure introduced into the brake booster 5). Since the cylinder pressure is reduced, pedal feeling is improved.

Further, when the wheel cylinder pressure is controlled by the hydraulic control circuit 1 for all the wheels, if there are a plurality of wheels in which the master cylinder pressure and the wheel cylinder pressure are close to each other, the plurality of wheels The master cylinder pressure may be controlled to be increased / decreased by the brake booster 5 in accordance with the slip state.

That is, in the case of such a pressure state, the brake booster 5 is controlled by taking a weighted average of the slip states of a plurality of wheels, rather than controlling the slip state of a single wheel. The effect is that the stability of control is improved. (Second Embodiment) Next, a second embodiment will be described.

In the first embodiment, the brake device mainly used in a small passenger car or a light vehicle has been described. In the present embodiment, the present invention is applied to a brake device mainly used in a truck system. Will be described. The present embodiment is suitable for a vehicle having front and rear piping.

A system called an air-over-hydraulic brake device as shown in FIG. 11 is adopted as the truck brake device. The components having the same functions as those of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted. The actuator (Act) 100 to which the depression state of the brake pedal 3 is transmitted is the first hydraulic pipe 3
5 and the second hydraulic pipe 36, respectively. The actuator 100 includes a first accumulator (Acc) 101 and a second accumulator 102.
Is connected to the first and second accumulators 101, 10 to generate gas pressure proportional to the pedal depression stroke.
It functions as a brake valve and a pressure control valve that supply the second to the first and second air masters 103 and 105. Further, the actuator 100 is
The ECU 25 is configured to be electrically controllable and receives the control signal to receive the accumulators 101, 102.
The flow rate of the gas pressure from the air to the air masters 103 and 105 can be varied.

The first and second accumulators 10 are usually used.
The gas pressure stored in 1, 102 is about 10 atm, and the air pressure may be stored by a compressor (not shown). First and second air masters 103, 1
05 are provided for the first and second hydraulic pipes 35, 36, respectively. In addition, each air master 103, 105
The area variable pistons 104 and 106 each have a larger area on the receiving surface to which the gas pressure is applied and a smaller area on the pressing surface for pressing the brake fluid. The variable area pistons 104 and 106 double the gas pressure to form a brake fluid pressure. The brake fluid pressure passes through the hydraulic lines 35 and 36 and is transmitted to the wheel cylinders 37 and 38 to generate braking force on the wheels.

Hydraulic pressure control valves 41 to 44 for the ABS actuator for the brake fluid are formed in the hydraulic pressure pipes 35 and 36, respectively.
The configurations of 44 to 44 and the reservoir 51 are the same as those in the first embodiment. Here, the description of the second hydraulic pipe 36 side is omitted.

In this embodiment, when the wheel cylinder pressure is reduced when the wheel slip becomes excessive,
A pump 107 is configured to suck the brake fluid flowing into the reservoir 51 and discharge it to the air master 103 side.
The pump 107 may be configured also in the second hydraulic pipe 36.

In such a structure, each structure may be controlled in accordance with the anti-skid control processing described in FIG. That is, in step 230 in FIG. 4, the gas pressure applied to the air master on the hydraulic piping side having wheels whose degree of wheel deceleration is larger than the first reference is reduced by the control of the actuator 100.
Thus, in steps 250, 280 and 290, instead of the brake booster control in the above-described embodiments, the accumulator 10 by the actuator 100 is used.
Air master 103, 105 of gas pressure from 1, 102
Controls the transmission pressure to. In this way, the Air Master 1
Even if the control of the gas pressure applied to 03, 105 is executed before the brake fluid pressure control, the amount of brake fluid flowing into the reservoir 51 can be suppressed. That is, in a vehicle such as a truck system, since the system of the hydraulic pipe for the brake is thick and the capacity of the wheel cylinder is large, the amount of decompression is larger than that of a passenger car and the like, which requires a very high pumping capacity. By constructing an anti-skid control device by hybridizing control of gas pressure and control of brake fluid pressure as in the present embodiment, the amount of inflow to the reservoir 51 can be reduced and the pump 107 having a small suction and discharge capability can be adopted. Or, the pump can be abolished.

The control on the gas pressure side does not necessarily have to be executed before the control on the brake fluid pressure, but may be reversed. That is, if the slip condition of the wheels is small to some extent or if the anti-skid control is started within a predetermined time, the slip is reduced by the control on the brake fluid pressure side, that is, the control of each hydraulic pressure control valve 41 to 44, and the slip is continued thereafter. When the pressure exceeds a predetermined level, the air master 1 that is the base pressure is controlled by the gas pressure side.
The brake fluid pressure generated by 03, 105 may be reduced. Even in this case, a similar effect can be obtained.

Further, it is not necessary to dispose a structure (actuator 100) for executing the gas pressure control on both the first hydraulic pipe 35 and the second hydraulic pipe 36. A configuration may be provided in which the gas pressure side control is performed only on the rear wheel side, which has a large number.

Needless to say, the present invention is not limited to the above-mentioned embodiments and can be carried out in various modes without departing from the technical scope of the present invention. (1) For example, in the first embodiment, the booster using the engine negative pressure is taken as an example, but the booster using pneumatic pressure, hydraulic pressure, or an electric booster is proposed. However, it goes without saying that the present invention can be applied to these various boosters.

(2) In the first embodiment, the check valves 53 and 55 are used in the hydraulic circuit that returns the brake fluid from the reservoirs 51 and 52 to the master cylinder side. Check valve 5 as shown in 12
Instead of 3,55, motor pumps 81,83 may be used. In this case, there is an advantage that operating noises and vibrations of the motor pumps 81 and 83 can be reduced.

That is, conventionally, when the brake booster 5 is used, as shown in FIG. 13 (b), the master cylinder pressure rises more than necessary and the differential pressure from the wheel cylinder pressure becomes large. Motor pump 81,83 by force
However, since the differential pressure is reduced by controlling the boosting action of the brake booster 5 as described above, the operation noise and vibration of the motor pumps 81 and 83 can be reduced. There is.

Further, when anti-skid control is performed by applying the present invention, in order to return the brake fluid from the wheel cylinder side to the reservoirs 51 and 52, and further to return the brake fluid from the reservoirs 51 and 52 to the master cylinder side. Since the operation frequency of the motor pumps 81 and 83 is reduced, it is possible to suppress the generation of operation noises and vibrations of the motor pumps 81 and 83 without impairing the vehicle body deceleration (deceleration G) during braking.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a brake control device according to a first embodiment.

FIG. 2 is a block diagram showing an electrical configuration of a brake control device.

FIG. 3 is a flowchart showing a main routine of processing of the first embodiment.

FIG. 4 is a flowchart illustrating anti-skid control according to the first embodiment.

FIG. 5 shows a state of anti-skid control, (a) is a graph showing a change in wheel speed, and (b) is a graph showing a change in brake hydraulic pressure.

FIG. 6 shows a state of anti-skid control by a hydraulic control circuit, (a) is a graph showing a change in wheel speed,
(B) is a graph showing a change in wheel deceleration, (c) is a graph showing a control mode, and (d) is a graph showing a change in wheel cylinder pressure.

FIG. 7 is an explanatory diagram showing a state of pressure reduction control by a brake booster.

FIG. 8 is an explanatory diagram showing a state of pressure reduction control by a brake booster and control of one wheel by a hydraulic control circuit.

FIG. 9 is an explanatory diagram showing a state of pressure reduction control by a brake booster and control of three wheels by a hydraulic control circuit.

FIG. 10 is an explanatory diagram showing a state of pressure reduction control by a brake booster and control of four wheels by a hydraulic control circuit.

FIG. 11 is an explanatory diagram showing a configuration of a brake control device according to a second embodiment.

FIG. 12 is an explanatory diagram showing a configuration of a brake control device according to another embodiment.

13A and 13B show a state of anti-skid control according to a conventional technique, FIG. 13A is a graph showing a change in wheel speed, and FIG.

[Explanation of symbols]

1 ... Hydraulic control circuit, 3 ... Brake pedal, 5 ... Brake booster, 7 ... Master cylinder, 9 ... Engine, 23 ... Negative pressure control valve, 29 ... Atmospheric pressure control valve, 37, 38, 39, 40 ...
Wheel cylinders, 41, 42, 43, 44, 45, 4
5, 47, 48 ... Hydraulic control valve, 51, 52 ... Reservoir,
75, 76, 77, 78 ... Wheel speed sensor, 81, 83
… Motor pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Sawada 1-1, Showa-cho, Kariya city, Aichi Prefecture DENSO CORPORATION

Claims (9)

[Claims] 1. A brake boosting means for boosting an acting force applied to a brake pedal by a driver's brake operation to apply to brake fluid on the master cylinder side, and a brake pipe provided to adjust a pressure of a wheel cylinder. And a brake boosting control means for reducing the boosting action of the brake boosting means when there is a request for reducing the wheel cylinder pressure, and a brake control device comprising: A brake control device comprising: a pressure control unit that drives and controls the pressure adjustment unit to perform a pressure reduction control of the wheel cylinder pressure when there is a pressure reduction request. 2. A brake control device for optimally controlling a slip state during wheel braking to improve braking performance, wherein when there is a demand for reducing the wheel cylinder pressure, first, the brake boosting force is applied. The control means reduces the boosting effect of the brake boosting means, and further, when the wheel slip condition is equal to or more than a predetermined value due to the reduction of the boosting effect, the pressure control means drives the pressure adjusting means. The brake control device according to claim 1, wherein the wheel cylinder pressure is reduced. 3. When the wheel cylinder pressure is controlled by the pressure control means for a predetermined wheel, and when the master cylinder pressure becomes higher than the wheel cylinder pressure by a predetermined value or more in the predetermined wheel, The brake control device according to claim 2, wherein the brake boosting control means performs control for reducing a boosting action of the brake boosting means. 4. When the wheel cylinder pressure is controlled by the pressure control means for all the wheels, the brake booster control means operates according to the slip state of the wheel having the highest wheel cylinder pressure. 3. The brake control device according to claim 2, wherein increase / decrease control of the boosting action of the brake boosting means is performed. 5. When the wheel cylinder pressure is controlled by the pressure control means for all the wheels, and when there are a plurality of wheels in which the master cylinder pressure and the wheel cylinder pressure are close to each other, the plurality of wheels are used. 5. The brake control device according to any one of claims 2 to 4, wherein the brake boosting control means performs the increase / decrease control of the boosting action of the brake boosting means according to the slip state of the wheel. 6. The increasing / decreasing control of the boosting action of the brake boosting means by the brake boosting control means is performed according to a weighted average value of slip states of the plurality of wheels. The described brake control device. 7. The brake control device according to any one of claims 1 to 6, wherein the brake boosting means is adjusted to two states of operation and stop of the boosting function. 8. A pressure source for generating a gas pressure corresponding to an acting force applied to a brake pedal by a driver's braking operation, and a fluid pressure corresponding to the gas pressure when the gas pressure acts. A master cylinder; a first conduit that connects the pressure source to the master cylinder; a wheel cylinder that receives a fluid pressure generated in the master cylinder to generate a wheel braking force; the master cylinder; A second pipe line communicating with the wheel cylinder, a first adjusting means for adjusting the gas pressure generated in the pressure source, and a fluid pressure applied to the wheel cylinder provided in the second pipe line. A second control means for adjusting, and a brake control device comprising: 9. A pressure source for generating a gas pressure proportional to an acting force applied to a brake pedal by a driver's braking operation, and a fluid pressure corresponding to the gas pressure when the gas pressure acts. A master cylinder, a wheel cylinder that receives the fluid pressure generated by the pressure source and the master cylinder to generate a wheel braking force, a conduit that connects the master cylinder and the wheel cylinder, and the wheel braking force Detecting means for detecting the wheel behavior of the wheel receiving the force, and a first adjustment capable of reducing the gas pressure applied to the master cylinder based on the detection result of the detecting means in order to avoid the locking tendency of the wheel. Means for causing the wheels to flow from the master cylinder to the wheel cylinders in order to avoid the tendency of the wheels to lock. The second that can control the fluid pressure to be reduced
And an executing unit that selectively executes the first adjusting unit and the second adjusting unit based on a predetermined condition.