JP4014682B2 - Brake device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicular brake device that assists the boosting action of a brake booster that increases the stepping force of a brake to improve braking performance.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a brake booster that boosts braking force by boosting the depression force of a brake pedal (so-called brake assist) is attached to a vehicle in order to reliably perform a driver's brake operation.
[0003]
As this type of brake booster, for example, by utilizing the difference between the negative pressure on the intake side of the engine and the atmospheric pressure, etc., the brake pedal depression force is boosted to apply a large force to the master cylinder side. A vacuum booster is known.
If this vacuum booster breaks down (failure), the desired boosting action cannot be exerted. Therefore, in recent years, it is determined whether or not the vacuum booster has failed, and it is determined that the vacuum booster has failed. Then, another control for executing a brake assist for driving a pump or the like to increase a brake fluid pressure to increase a braking force is being studied.
[0004]
[Problems to be solved by the invention]
However, in the technology that combines the boosting action by the vacuum booster described above and the pressure amplification by another brake assist, when the brake assist to increase the brake fluid pressure by driving a pump or the like is stopped when the vehicle is stopped, the vacuum booster is Since the vehicle has fallen, the braking force suddenly decreases. For example, when the vehicle stops on a steep slope, the vehicle may start to move by gravity.
[0005]
The present invention has been made in view of the above problems, and when the boosting action of the brake booster cannot be fully exhibited, the brake control is preferably performed when the vehicle is stopped by controlling the driving of another brake assist. An object of the present invention is to provide a vehicle brake device that can perform the above-described operation.
[0006]
[Means for Solving the Problems]
  In the first aspect of the invention, the first brake hydraulic pressure generating means generates the first brake hydraulic pressure by receiving a boosting action by a brake booster that boosts the pedaling force when the occupant depresses the brake pedal. The wheel braking force generating means receives the first brake fluid pressure via the pipe and generates a wheel braking force. When the first detection means detects the failure or the function deterioration of the brake booster, the increase means causes the brake fluid pressure applied to the wheel braking force generation means to be higher than the first brake fluid pressure. The brake fluid pressure increases to 2. Further, when the second detecting means detects the stop state of the vehicle (when the increasing means is executed), the brake fluid applied to the wheel braking force generating means until the predetermined releasing condition is satisfied by the holding means. PressureFirstHigher than 1 brake fluid pressureThe second brake fluid pressureHold.
[0007]
  In other words, when the increasing means is executed so as to compensate for the failure or deterioration of the function of the brake booster, when the execution of the increasing means is terminated when the vehicle is stopped, an external force is applied to move the vehicle, particularly on a slope. In some cases, the braking force may be insufficient. Therefore, in the present invention, when the vehicle is stopped, the execution of the increasing means is not terminated as it is, but only when a predetermined release condition that prevents the vehicle from moving (that is, a condition for stopping the execution of the increasing means) is satisfied. The execution of the increasing means is stopped. For this reason, even when the brake booster fails or declines in function, for example, even when the vehicle stops on a slope, a sufficient braking force is ensured. For example, the vehicle does not move freely due to gravity, and is extremely safe. is there.
  In the present invention, the second brake fluid pressure, which is a high brake fluid pressure formed by pressure amplification at the time of braking, is maintained, so that the ability to stop the vehicle is high and suitable.
Furthermore, in the present invention, the following ( i ) ~ ( iii ) Is used.
( i ) The holding means holds the brake fluid pressure applied to the wheel braking force generating means until the accelerator pedal is depressed next time after the second detecting means detects that the vehicle is stopped.
That is, when the accelerator pedal is stepped on, a force for starting the vehicle is applied, so it is considered that there is no problem even if the brake fluid pressure is reduced at that time. Further, it is necessary to reduce the brake fluid pressure for starting.
Therefore, ( i In the configuration of), the brake hydraulic pressure applied to the wheel braking force generating means is maintained until the accelerator pedal is depressed next time after it is detected that the vehicle is in a stopped state, that is, during the period when it is desired to maintain the stopped state of the vehicle. Yes. As a result, even if the vehicle stops on a slope, for example, the vehicle does not start on its own and is extremely safe.
( ii ) The holding means holds the brake fluid pressure applied to the wheel braking force generating means until the parking brake is operated by the occupant after the second detecting means detects that the vehicle is stopped.
In other words, since it is considered that it is a period in which it is desired to maintain the stop state of the vehicle from when the vehicle stops to when the parking brake is operated, ii In this configuration, the brake fluid pressure applied to the wheel braking force generating means is maintained until the parking brake is operated. As a result, even if the vehicle stops on a slope, for example, the vehicle does not start on its own and is extremely safe.
( iii ) When the vehicle is an automatic vehicle, the holding means detects the wheel braking force after the second detection means detects that the vehicle is stopped until the shift lever is set to the parking position by the occupant. The brake fluid pressure applied to the generating means is maintained.
In other words, in the case of an automatic vehicle, it is considered that it is a period during which it is desired to keep the vehicle stopped until the shift lever is set to the parking position (usually indicated by P) after the vehicle stops. ( iii In this configuration, the high brake fluid pressure applied to the wheel braking force generating means is maintained until the shift lever is set to the parking position. As a result, even if the vehicle stops on a slope, for example, the vehicle does not start on its own and is extremely safe.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a vehicle brake device according to the present invention will be described in detail with reference to the drawings by way of examples (examples).
Example 1
a) First, a schematic configuration of the vehicle brake device according to the present embodiment will be described with reference to FIG. The vehicle brake device of the present embodiment includes a brake booster and a pressure amplifying mechanism including a pump and the like in order to perform brake assist.
[0017]
As shown in FIG. 1, the vehicle brake device of this embodiment includes a vacuum booster 1 as a brake booster. A brake pedal 2 is connected to the vacuum booster 1 on the input side, and the output side A tandem master cylinder 3 is connected to the tandem. The master cylinder 3 is connected to a master reservoir 4 and a hydraulic control circuit 6 composed of two hydraulic systems of first and second piping systems A and B of the front and rear piping.
[0018]
The vacuum booster 1 is provided with a negative pressure chamber (constant pressure chamber) 11 and a variable pressure chamber 12 partitioned by a diaphragm 8. The vacuum booster 1 exhibits a boosting action as the brake pedal 2 is depressed, and introduces a negative pressure of an intake manifold (intake negative pressure) generated by an engine (not shown) into the constant pressure chamber 11 and is large. Atmospheric pressure is introduced into the variable pressure chamber 12, and the force applied to the piston 7 of the master cylinder 3 is increased using the pressure difference between the two chambers 11 and 12.
[0019]
In the hydraulic control circuit 6, the right front (FR) wheel cylinder 21 and the left front (FL) wheel cylinder 22 communicate with each other through the first piping system A. Further, the wheel cylinder 23 of the right rear (RR) wheel and the wheel cylinder 24 of the left rear (RL) wheel are communicated with each other via the second piping system B.
[0020]
The first piping system A has a well-known pressure-increasing control valve 25 and pressure-reducing control valve 31 for controlling the hydraulic pressure of the FR wheel cylinder 21 and the hydraulic pressure of the FL wheel wheel cylinder 22. The pressure increase control valve 26 and the pressure reduction control valve 32 are provided, and the second piping system B includes a pressure increase control valve 27 and a pressure reduction control valve 33 for controlling the hydraulic pressure of the wheel cylinder 23 of the RR wheel, A pressure increase control valve 28 and a pressure reduction control valve 34 for controlling the hydraulic pressure of the wheel cylinder 24 of the RL wheel are provided.
[0021]
Here, the first piping system A will be described.
The first piping system A is provided with a master cylinder cut valve (SMC valve) 36 that communicates and shuts off the pipe line 51 on the master cylinder 3 side from the respective pressure increase control valves 25 and 26. A reservoir 41 for temporarily storing brake oil discharged from the pressure reducing control valves 31 and 32 and a pump 43 for pumping the brake oil to the pipeline 51 are provided.
[0022]
Further, when the wheel cylinder pressure is increased, a pipe 53 for supplying brake oil directly from the master cylinder 3 to the pump 43 is provided, and this pipe 53 has a reservoir for communicating and blocking the pipe 53. A cut valve (SRC valve) 38 is provided.
[0023]
The pump 43 is driven by a pump motor 46 and constitutes a pressure amplification mechanism together with the SMC valve 36 and the SRC valve 38. In this pressure amplifying mechanism, the hole cylinder pressure can be increased more than the master cylinder pressure by driving the pump 43 with the SRC valve 38 opened and the SMC valve 36 shut off.
[0024]
An accumulator 47 that suppresses the pulsation of the internal hydraulic pressure is provided in the brake oil discharge path from the pump 43.
On the other hand, in the second piping system B, similarly to the first piping system A, the pressure increasing control valves 27 and 28, the pressure reducing control valves 33 and 34, the SMC valve 37, the reservoir 42, the pump 44, the accumulator 48, The SRC valve 39, the pipelines 52 and 54, and the like are provided at similar locations.
[0025]
b) Further, as shown in FIG. 2, the ECU 61 that controls the above-described vehicle brake device is mainly configured by a microcomputer including a well-known CPU 61a, ROM 61b, RAM 61c, input / output unit 61d, bus line 61e, and the like. ing.
The ECU 61 includes a wheel speed sensor 62 that is disposed on each wheel and detects a wheel speed, a brake switch 63 that detects depression of the brake pedal 2, an accelerator switch 64 that detects depression of an accelerator pedal (not shown), and a parking brake (not shown). A parking switch 66 for detecting that the vehicle is pulled, a gear position sensor 67 for detecting that a shift lever (not shown) is set to the parking position in the case of an automatic vehicle, and the pressure in the constant pressure chamber 11 in the vacuum booster 1. From a constant pressure chamber pressure sensor 68 to detect, a pressure chamber pressure sensor 69 to detect the pressure in the pressure chamber 12, an M / C pressure sensor 71 to detect the master cylinder pressure, a W / C pressure sensor 72 to detect the wheel cylinder pressure, and the like. Signal is input.
[0026]
The ECU 61 also receives control signals for driving control actuators such as pressure increase control valves 25 to 28, pressure reduction control valves 31 to 34, SMC valves 36 and 37, SRC valves 38 and 39, and a pump motor 46, which are electromagnetic valves. Is output.
c) Next, the control processing in the present embodiment will be described based on the flowchart of FIG. 3 and the graphs of FIGS.
[0027]
First, in step 100 of FIG. 3, it is determined whether or not the brake pedal 2 is depressed by whether or not the brake switch 63 is on. If an affirmative determination is made here, the process proceeds to step 110, whereas if a negative determination is made, the same determination is repeated again.
In step 110, the constant pressure chamber pressure (negative pressure) P is detected based on the signal from the constant pressure chamber pressure sensor 66.
[0028]
In the following step 120, whether or not the vacuum booster (V / B) 1 has failed is determined by whether or not the constant pressure chamber pressure P, which is a negative pressure, exceeds a determination value kP. That is, when an appropriate negative pressure is not supplied to the constant pressure chamber, it is determined that the vacuum booster 1 has failed. If an affirmative determination is made here, the process proceeds to step 130, whereas if a negative determination is made, the process returns to step 100.
[0029]
At this time, by setting a criterion for determination low, that is, by setting a function deterioration determination value such that the function deterioration determination value <kP, a function deterioration that does not cause a failure is detected. Depending on the result, pressure amplification similar to that at the time of failure (however, the degree of pressure amplification may be small) may be performed.
[0030]
In step 130, since it is determined that the vacuum booster 1 has failed, in order to supplement the boosting action of the vacuum booster 1, an increasing means is executed. That is, pressure amplification is performed by a pressure amplification mechanism.
Specifically, the SMC valves 36 and 37 are closed to shut off the pipelines from the master cylinder 3 to the wheel cylinders 21 to 24, and the SRC valves 38 and 39 are opened to suck the pumps 43 and 44 from the master cylinder 3. The pump motor 46 is energized to drive the pumps 43 and 44 in a state where the pipe line leading to is communicated. As a result, the wheel cylinder pressure can be increased by compensating for the failure of the vacuum booster 1.
[0031]
In the following step 140, the wheel speed Vw of the four wheels is detected based on the signal from each wheel speed sensor 62.
In subsequent step 150, a value Vw corresponding to the vehicle body speed Vb is selected from the wheel speeds Vw of the four wheels, and is set as the selected wheel speed Vws. For example, the average value or the maximum value of the wheel speeds Vw of four wheels is set as the selected wheel speed Vws.
[0032]
In subsequent step 160, it is determined whether or not the vehicle is in a stopped state based on whether or not the selected wheel speed Vws is equal to or less than a determination value kVw (for example, 4 km / s). If an affirmative determination is made here, the process proceeds to step 170, whereas if a negative determination is made, the process returns to step 130.
[0033]
In step 170, since the vehicle is in a stopped state, it is determined whether a condition for performing control when the vehicle is stopped, that is, control for preventing insufficient braking force when the vehicle is stopped, is satisfied. Specifically, it is determined whether or not a predetermined time T1 has elapsed since execution of the increasing means. If an affirmative determination is made here, the process proceeds to step 180. If a negative determination is made, the process returns to step 130.
[0034]
In step 180, since the condition for executing the control when the vehicle is stopped is satisfied, the execution of the increasing means is stopped (released), and the present process is temporarily ended.
Specifically, the SMC valves 36 and 37 are opened to connect the pipelines from the master cylinder 3 to the wheel cylinders 21 to 24, and the SRC valves 38 and 39 are closed to suck the pumps 43 and 44 from the master cylinder 3. And the pump motor 46 is turned off to stop the pumps 43 and 44. Thereby, the control of the wheel cylinder pressure increase performed to compensate for the failure of the vacuum booster 1 can be stopped.
[0035]
That is, according to the above-described processing, after a predetermined time T1 from when the vehicle stops, the pressure amplification of the wheel cylinder pressure can be stopped to reduce the braking force of the wheels.
d) Next, the function and effect of this embodiment will be described with reference to FIG.
As shown in FIG. 4, for example, when the brake pedal 2 is depressed from time t0, the wheel speed Vw and the vehicle body speed Vb gradually decrease accordingly. When the vacuum booster 1 fails at time t1, pressure amplification by the pressure amplification mechanism is started to compensate for the boosting action. Therefore, after that, the master cylinder pressure (M / C pressure) hardly increases (however, depending on the state of failure), but the wheel cylinder pressure (W / C pressure) increases.
[0036]
Next, when the wheel speed Vw (specifically, the selected wheel speed Vws) becomes equal to or less than the determination value kVw at time t2, it is determined that the vehicle has stopped. Then, at a time t3 after a predetermined time T1 from the determination of the stop state, the pressure amplification by the pressure amplification mechanism is stopped to reduce the wheel cylinder pressure.
[0037]
That is, in the present embodiment, during braking, the pressure increasing means that compensates for the boosting action of the vacuum booster 1 is executed, and when it is determined that the vehicle is in a stopped state, the increasing means is not canceled as it is. The increase means is released after waiting for a predetermined time T1.
[0038]
This is because, since the vacuum booster 1 has failed, if it is determined that the vehicle is in a stopped state, if the increasing means is released as it is, the braking force is insufficient, and for example, when the vehicle stops on a slope, This is because the vehicle may move freely due to gravity despite the fact that the pedal 2 is stepped on. As a countermeasure, in this embodiment, after waiting for a predetermined time T1, the increasing means is released. That is, when a certain time has passed since the vehicle stopped, it is assumed that the occupant performs some kind of stop operation such as pulling the parking brake during that time, and the increasing means is released.
[0039]
As a result, when the vacuum booster 1 has failed, even if it stops on a hill or the like, the vehicle does not start unexpectedly, and there is a remarkable effect that it is extremely safe.
(Example 2)
Next, Example 2 will be described. This Example is different from Example 1 only in condition determination for executing control when the vehicle is stopped. This point will be described in detail.
[0040]
In this embodiment, even when it is detected that the vehicle is stopped, the pressure amplification by the pressure amplification mechanism described above is performed until the accelerator pedal (not shown) is depressed next time, and the accelerator pedal is depressed. If this is detected based on the signal from the accelerator switch 64, the pressure amplification by the pressure amplification mechanism is stopped, and the wheel cylinder pressure is reduced.
[0041]
In other words, when the accelerator pedal is depressed, a force to start the vehicle is applied. At that time, there is no problem even if the brake hydraulic pressure is reduced, that is, there is no arbitrary movement due to the gravity of the vehicle. Therefore, it is necessary to reduce the brake hydraulic pressure. Therefore, in this embodiment, the high wheel cylinder pressure is maintained until the accelerator pedal is depressed next time.
[0042]
As a result, the same effects as in the first embodiment are achieved, and when the predetermined time T1 elapses, the braking force of the wheels is not reduced as it is, but the operation for starting is started and the braking force is reduced. It is safer.
(Example 3)
Next, a third embodiment will be described. This embodiment is different from the first embodiment only in condition determination for executing control when the vehicle is stopped, and this point will be described in detail.
[0043]
In this embodiment, even when it is detected that the vehicle is stopped, the pressure amplification by the pressure amplification mechanism described above is performed until the brake pedal 2 is actually returned by the passenger, and the brake pedal 2 is returned. If this is detected based on the signal from the brake switch 63, the pressure amplification by the pressure amplification mechanism is stopped to reduce the wheel cylinder pressure.
[0044]
That is, since it is considered that it is a period during which it is desired to maintain the stop state of the vehicle until the brake pedal 2 is returned after the vehicle stops, in this embodiment, a high wheel cylinder pressure is required until the brake pedal 2 is returned. Holding.
As a result, the same effects as in the first embodiment can be obtained, and when the predetermined time T1 elapses, the braking force of the wheels is not reduced as it is, but the intention of the next stop or the start of the vehicle is displayed. Since power is reduced, safety is even higher.
Example 4
Next, a fourth embodiment will be described. This embodiment is different from the first embodiment only in condition determination for executing control when the vehicle is stopped, and this point will be described in detail.
[0045]
In this embodiment, even when it is detected that the vehicle is stopped, the pressure amplification by the pressure amplification mechanism described above is performed until the parking brake (not shown) is actually pulled by the occupant. Is detected based on a signal from the parking switch 66, the pressure amplification by the pressure amplification mechanism is stopped to reduce the wheel cylinder pressure.
[0046]
In other words, it is considered that it is a period during which it is desired to keep the vehicle stopped until the parking brake is applied after the vehicle stops. In this embodiment, the high wheel cylinder pressure is maintained until the parking brake is returned. is doing.
As a result, the same effects as in the first embodiment can be obtained, and when the predetermined time T1 has elapsed, the braking force is reduced after a complete stop operation of the vehicle without reducing the braking force of the wheels. It is safer.
(Example 5)
Next, a fifth embodiment will be described. This embodiment is different from the first embodiment only in condition determination for executing control when the vehicle is stopped, and this point will be described in detail.
[0047]
In the present embodiment, when the vehicle is an automatic vehicle, even when it is detected that the vehicle is in a stopped state, until the shift lever (not shown) is actually set to the parking position by the occupant, When the pressure amplification by the pressure amplification mechanism is performed and it is detected based on the signal from the gear position sensor 67 that the parking position is set, the pressure amplification by the pressure amplification mechanism is stopped and the wheel cylinder is stopped. The pressure is reduced.
[0048]
That is, it is considered that it is a period during which it is desired to maintain the stop state of the vehicle until the shift lever is set at the parking position after the vehicle stops. In this embodiment, until the shift lever is set at the parking position. Holds high wheel cylinder pressure.
[0049]
As a result, the same effects as in the first embodiment can be obtained, and when the predetermined time T1 has elapsed, the braking force is reduced after a complete stop operation of the vehicle without reducing the braking force of the wheels. It is safer.
Needless to say, 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.
[0050]
(1) For example, in the first to fifth embodiments, the brake booster using an engine negative pressure and atmospheric pressure is taken as an example. However, as the brake booster, other pressures such as an accumulator are used. The one using the source can be adopted. Moreover, this invention is applicable also to what used the hydro booster.
[0051]
  (2) In the first to fifth embodiments, the determination of the vacuum booster failure or the function deterioration is performed in the state of the constant pressure chamber pressure.a) to c)Various methods such as can be adopted.
  a)When the pressure difference (P1-P2) between the variable pressure chamber pressure P1 and the constant pressure chamber pressure P2 is equal to or less than a predetermined value, it can be determined that the vacuum booster has failed or deteriorated in function.
[0052]
  b)For example, when the pressure difference (PT−P1) between the atmospheric pressure PT, which is the outside world, and the variable pressure chamber P1 is less than a predetermined determination value, it can be determined that a failure or functional degradation has occurred in the vacuum booster.
  c)Further, when the pressure difference (PT−P2) between the atmospheric pressure PT and the constant pressure chamber P2 is below a predetermined determination value, it can be determined that the vacuum booster has failed or deteriorated in function.
[0053]
  (3) In the first to fifth embodiments, the pressure amplifying mechanism using an SMC valve is taken as an example, but the wheel cylinder pressure is increased in order to compensate for a vacuum booster failure or reduced function. For example, the following examplea), b)Can be adopted.
[0054]
  a)Instead of the SMC valve of the above embodiment, a configuration in which the proportional control valve is reversely connected, that is, a configuration in which the high pressure side (input side) of the proportional control valve is the wheel cylinder side and the low pressure side (output side) is the master cylinder side is adopted. it can. In this case, it is desirable to set the break point pressure of the proportional control valve as low as possible.
[0055]
In other words, the proportional control valve has the same pressure on both the high pressure side and the low pressure side even if the pump is driven below the breakpoint pressure. This is because it can be used as a pressure amplification mechanism by driving the pump.
[0056]
  b)For example, the suction side of the pump may be connected to the master reservoir instead of the master cylinder, and the SRC valve may be arranged in the pipeline. In this case, the brake oil between the master cylinder and the wheel cylinder is not moved to the wheel cylinder side and the wheel cylinder pressure is increased as in the above embodiment, but the brake oil is supplied from another place (master reservoir). Since the wheel cylinder pressure is increased by replenishment, there is an advantage that the wheel cylinder pressure can be quickly increased and the braking performance is high.
[0057]
(4) In the first to fifth embodiments, the pressure amplification is performed by the pressure amplification mechanism until a predetermined condition such as a predetermined time is satisfied after the vehicle is determined to be stopped. Instead of pressure amplification by the mechanism, a high pressure control valve may be driven to maintain a high wheel cylinder pressure.
[0058]
Specifically, when it is determined that the vehicle is in a stopped state, the pressure amplification by the pressure amplification mechanism is stopped, and the pressure increase control valve is turned on to shut off to maintain a high wheel cylinder pressure. Also good.
(5) In the first to fifth embodiments, the high wheel cylinder pressure during braking is maintained as it is until a predetermined condition such as a predetermined time is satisfied after the vehicle is determined to be stopped. However, since it is only necessary to prevent unexpected movement of the vehicle due to insufficient braking force at the time of stopping, the wheel cylinder pressure may be reduced to some extent while ensuring the braking force required at the time of stopping.
[0059]
For example, the wheel cylinder pressure may be reduced by reducing the driving force of the pump, adjusting the closed state of the SRC valve, or opening the pressure reduction control valve at a predetermined rate. In this case, since the wheel cylinder pressure is reduced to some extent, there is an advantage that the pressure shock (to the master cylinder side) when the SMC valve is opened accompanying the stop of the pressure amplification mechanism can be reduced.
[0060]
(6) Also, when the vacuum booster function is reduced due to fluctuations in the intake manifold negative pressure, the vacuum booster function is restored after the vehicle stops, that is, the negative pressure or engine speed (idle speed) is normalized. Is detected, the pressure amplification is terminated. The normalization can be detected from a vacuum booster negative pressure or the like.
[0061]
(7) In Examples 1 to 5, the front and rear pipes are taken as an example, but X pipes may be used instead.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating a vehicle brake device according to a first embodiment.
2 is a block diagram showing an electrical configuration of Embodiment 1. FIG.
FIG. 3 is a flowchart illustrating control processing according to the first exemplary embodiment.
4 is a graph showing a pressure change by the control processing of Example 1. FIG.
[Explanation of symbols]
1 ... Vacuum booster
2 ... Brake pedal
3. Master cylinder
6 ... Hydraulic control circuit
11 ... Constant pressure chamber (negative pressure chamber)
12 ... Transformer room
21, 22, 23, 24 ... wheel cylinders
36, 37 ... Master cut valve (SMC valve)
38, 39 ... Reservoir cut valve (SRC valve)
43, 44 ... Pump
46 ... Pump motor

Claims (1)

A brake booster that boosts the pedaling force of the passenger when the brake pedal is depressed,
Brake fluid pressure generating means for generating a first brake fluid pressure in response to a boosting action by the brake booster;
Wheel braking force generating means for receiving the first brake fluid pressure and generating wheel braking force;
A conduit communicating the brake fluid pressure generating means and the wheel braking force generating means;
First detecting means for detecting failure or reduced function of the brake booster;
When the first detection means detects a failure or a function deterioration of the brake booster, a second brake fluid pressure applied to the wheel braking force generation means is higher than the first brake fluid pressure. Increasing means for increasing the brake fluid pressure of
Second detection means for detecting a stop state of the vehicle;
When the increasing means is executed and the second detecting means detects that the vehicle is stopped, the brake hydraulic pressure applied to the wheel braking force generating means until a predetermined release condition is satisfied. Holding means for holding the second brake hydraulic pressure higher than the first brake hydraulic pressure;
A vehicle brake device comprising:
The holding means is
(I) a holding unit that holds a brake fluid pressure applied to the wheel braking force generation unit until the accelerator pedal is depressed next time after the second detection unit detects that the vehicle is stopped.
(Ii) holding means for holding the brake fluid pressure applied to the wheel braking force generating means until the parking brake is activated by the occupant after the second detecting means detects that the vehicle is stopped. ,
(Iii) When the vehicle is an automatic vehicle, the wheel control is not performed until the shift lever is set to the parking position by the occupant after the second detection means detects that the vehicle is stopped. Holding means for holding the brake fluid pressure applied to the power generation means;
1 Tanedea of is,
The increasing means includes a master cylinder cut valve and
A pump that increases the brake fluid pressure applied to the wheel braking force generating means to a second brake fluid pressure higher than the first brake fluid pressure by driving in a state in which the master cylinder cut valve is shut off;
When the stop state of the vehicle is detected by the second detection means
It said retaining means is a second brake fluid pressure which has been increased by the pump, the while securing the braking force required for stopping the vehicle brake system, characterized that you reduce the driving force of the pump.

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