JP2008179228A - Hydraulic braking device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong a controllable time of a brake while preventing suction of air from a reservoir tank at generation of failure such as liquid leakage in a hydraulic braking device. <P>SOLUTION: A liquid surface switch 80 detects reduction of a brake liquid surface to a predetermined lower limit liquid surface of the reservoir tank. A timer part 108 measures a passing time from a first time when the liquid surface switch detects reduction of the brake liquid surface by inclination of the liquid surface in the reservoir tank to a second time when the liquid surface switch detects reduction of the brake liquid surface when the vehicle is not accelerated/decelerated and the brake liquid surface is horizontal. A liquid leakage presumption part 103 obtains the corresponding liquid surface height from a liquid surface height map retaining part 102 with reference to acceleration of the first time and calculates a brake liquid surface reduction speed from the passing time and the liquid surface height. A postponement time calculation part 110 calculates a postponement time until control of the hydraulic braking device is stopped based on the brake liquid surface reduction speed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic brake device, and more particularly to a control technique when a hydraulic brake device leaks.

  In the hydraulic brake device, a liquid level switch is provided in a reservoir tank to detect a decrease in brake fluid to a preset lower limit liquid level. The brake fluid level in the reservoir tank may decrease due to fluid leakage due to piping perforations and internal consumption due to wear of the brake pads and rotor. If normal brake control is continued even after the liquid has leaked, air may be sucked into the pipe to the master cylinder, which may make it difficult to generate a braking force. In particular, in the case of a control brake that drives the pump and sends brake fluid to the actuator, the brake fluid is consumed in a short time by driving the pump, and air is likely to be sucked. It is preferable to prohibit the control.

When the brake fluid leakage is large, it is necessary to prohibit the control promptly. However, when the brake leakage is small or due to internal consumption, air suction will not occur immediately and the braking force will not decrease. Therefore, it is desirable to extend the time that the brake can be used as much as possible. For this purpose, it is necessary to detect the rate of liquid leakage. As such a technique, for example, Patent Document 1 describes that a liquid leak rate is detected based on outputs of two or more liquid level switches.
JP 2000-272497 A

  In Patent Document 1, two or more liquid level switches are provided in the reservoir tank. However, providing a plurality of switches in this manner leads to an increase in cost and sometimes it is difficult to connect the switches.

  The present invention has been made in view of such a situation, and an object of the present invention is to estimate a liquid level lowering rate at the time of liquid leakage by providing only one liquid level switch in a reservoir tank in a hydraulic brake device, and to perform brake control. It is to provide a technology that makes it possible to prolong life.

  One aspect of the present invention is a hydraulic brake device that supplies brake fluid from a reservoir tank through a conduit to generate braking force on the vehicle. This device includes an acceleration sensor that detects acceleration generated in the vehicle, a liquid level switch that detects a decrease in the brake fluid level to a predetermined lower limit fluid level of the reservoir tank, A liquid level map holding unit that holds the liquid level height from the lower limit liquid level when the brake liquid level falls below the liquid level switch due to the inclination of the brake liquid level, and the inclination of the liquid level in the reservoir tank From the first time when the fluid level switch detects a decrease in the brake fluid level, the fluid level switch detects a decrease in the brake fluid level when the vehicle is not accelerating / decelerating and the brake fluid level is horizontal. A timer unit that measures an elapsed time up to two times, a corresponding liquid level height is acquired from the liquid level map holding unit with reference to the acceleration of the vehicle at the first time, and the elapsed time and the Comprising a liquid leakage estimator for calculating a brake fluid surface reduction rate from Mendaka of, and a grace time calculation unit for calculating a delay time until stopping the control of the device based on the brake fluid level lowering rate.

  Even when the brake fluid level in the reservoir tank is above the lower limit fluid level when leveling, the brake fluid sways as the vehicle accelerates and decelerates, causing the fluid level to temporarily fall below the fluid level switch and the fluid level switch to turn on. There is a case. In this aspect, the grace time until the brake control is stopped is calculated by estimating the brake fluid level lowering speed of the reservoir tank at the time of liquid leakage using such a phenomenon. By doing so, it is possible to continue the brake control for as long as possible even when the brake fails.

  The liquid leakage estimation unit calculates the remaining amount of brake fluid up to the lower limit liquid level at the first time based on the liquid level height and the cross-sectional area of the reservoir tank, and based on the remaining liquid amount and the elapsed time, The brake fluid level lowering speed may be calculated. By doing so, the brake fluid level lowering speed can be estimated relatively accurately.

  The fluid level switch is arranged at a position where there is a surplus fluid amount from when the brake fluid level reaches the lower limit fluid level until air suction into the conduit occurs, and the grace time calculation unit reduces the brake fluid level Based on the speed and the amount of surplus fluid, a grace time until the brake fluid level decreases to the conduit outlet may be calculated. As described above, when the reservoir tank has a surplus liquid amount, the brake control is continued until the time immediately before the brake fluid level is reduced to the outlet of the conduit, which is calculated according to the brake fluid level lowering speed. Can do.

  Another aspect of the present invention is a method for controlling a hydraulic brake device. The hydraulic brake device is provided with a liquid level switch for supplying a brake fluid from a reservoir tank through a conduit to generate a braking force on the vehicle and detecting a decrease in the brake fluid level to a predetermined lower limit fluid level of the reservoir tank. It has been. In this method, the liquid level height from the lower limit liquid level when the brake liquid level falls below the liquid level switch due to the inclination of the brake liquid level in the reservoir tank during acceleration / deceleration of the vehicle is stored in a memory in advance. In addition, from the first time when the liquid level switch detects a decrease in the brake liquid level due to the inclination of the liquid level in the reservoir tank, the liquid level switch when the vehicle is not accelerating / decelerating and the brake liquid level is horizontal. Measure the elapsed time until the second time when the liquid level is detected, and obtain the corresponding liquid level height from the liquid level map holding unit with reference to the acceleration of the vehicle at the first time, The brake fluid level lowering speed is calculated from the elapsed time and the fluid level height, and a delay time until the control of the hydraulic brake device is stopped based on the brake fluid level lowering speed is calculated. From the second time Grace During stops the control of the hydraulic brake device when the elapsed.

  According to this aspect, the grace time until the brake fluid level decreases and air suction occurs is calculated, and the brake control is prohibited after the grace time elapses. In this way, the brake control can be continued for as long as possible even when the brake fails.

  According to the present invention, in the hydraulic brake device, it is possible to estimate the rate of decrease of the liquid level at the time of liquid leakage and extend the usable time of brake control by providing only one liquid level switch in the reservoir tank. Become.

  FIG. 1 shows a configuration of a hydraulic brake device 200. The hydraulic brake device 200 is a so-called electronically controlled brake (ECB), which detects an operation amount of a brake pedal 72 provided in a vehicle interior with a sensor, and is output from the ECU 100 that is issued in response to the operation of the brake pedal. The brakes can be operated independently according to the command.

  The brake pedal 72 is provided with a stroke sensor 46 for detecting the depression stroke. The master cylinder 74 pumps brake oil, which is hydraulic fluid, in response to the driver's depression operation of the brake pedal 72.

  One end of a brake hydraulic control conduit 76 for the right front wheel and a brake hydraulic control conduit 78 for the left front wheel are connected to the master cylinder 74, and these brake hydraulic control conduits exhibit the braking force of the right front wheel and the left front wheel, respectively. It is connected to wheel cylinders 15FR, 15FL for the right front wheel 14FR and the left front wheel 14FL. The right master cut valve 22FR and the left master cut valve 22FL are inserted in the middle of the brake hydraulic pressure control conduits 76, 78 for the right front wheel 14FR and the left front wheel 14FL. The right master cut valve 22FR and the left master cut valve 22FL are open when not energized, and switch to a closed state when a brake operation is detected (this is referred to as a “normally open type”).

  A right master pressure sensor 48FR and a left master pressure sensor 48FL for measuring master cylinder hydraulic pressures on the right front wheel 14FR side and the left front wheel 14FL side are provided in the middle of the brake hydraulic pressure control conduits 76 and 78, respectively. When the driver depresses the brake pedal 72, the stroke sensor 46 detects the amount of depression, but the master cylinder fluid is detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL assuming that the stroke sensor 46 has failed. The depressing operation force of the brake pedal 72 is also detected by measuring the pressure. The master cylinder hydraulic pressure is monitored by two pressure sensors from the viewpoint of fail-safe.

  The reservoir tank 26 is connected to the master cylinder 74, and the stroke simulator 24 that creates the operation amount and reaction force of the driver is connected via the on-off valve 23. The on-off valve 23 is a normally open solenoid valve that is open when de-energized and switches to open when the brake is operated. One end of a hydraulic supply / discharge conduit 28 is connected to the reservoir tank 26. The hydraulic supply / discharge conduit 28 is provided with an oil pump 34 driven by a motor 32. The discharge side of the oil pump 34 is a high-pressure conduit 30, and an accumulator 50 and a relief valve 53 are provided. The accumulator 50 accumulates brake oil that has been brought to a high pressure in the range of 14 to 22 MPa (hereinafter referred to as “control range”) by the oil pump 34. The relief valve 53 opens when the accumulator pressure is abnormally high, for example, a high pressure such as 25 MPa, and releases high-pressure brake oil to the hydraulic supply / discharge conduit 28.

  The high pressure conduit 30 is provided with an accumulator pressure sensor 51 that measures the accumulator pressure. An accumulator pressure, which is the output of the accumulator pressure sensor 51, is input to the ECU 100 described later, and the motor 32 is controlled so that the accumulator pressure falls within the control range.

  Each of the high-pressure conduits 30 is closed when not energized (this is referred to as “normally closed type”). When necessary, the high-pressure conduit 30 is an electromagnetic flow control valve that is used for pressure increase of the wheel cylinder, that is, a linear valve. Via pressure valves 40FR, 40FL, 40RR, 40RL, they are connected to a wheel cylinder 15FR for the right front wheel 14FR, a wheel cylinder 15FL for the left front wheel 14FL, a wheel cylinder 15RR for the right rear wheel 14RR, and a wheel cylinder 15RL for the left rear wheel 14RL. Yes.

  Disc brakes are provided on the right front wheel 14FR, the left front wheel 14FL, the right rear wheel 14RR, and the left rear wheel 14RL of the vehicle, and the brake pads are pressed against the disc by driving the wheel cylinders 15FR, 15FL, 15RR, and 15RL, respectively. In order to demonstrate the braking power.

  The right front wheel wheel cylinder 15FR and the left front wheel wheel cylinder 15FL are hydraulically fed and discharged via normally closed pressure reducing valves 42FR and 42FL, which are electromagnetic flow control valves used for pressure reduction when necessary, that is, linear valves. Connected to conduit 28. Further, the wheel cylinder 15RR for the right rear wheel and the wheel cylinder 15RL for the left rear wheel are connected to the hydraulic supply / discharge conduit 28 via normally open pressure reducing valves 42RR and 42RL, respectively.

  Near the right front wheel, left front wheel, right rear wheel, and left rear wheel wheel cylinders 15FR, 15FL, 15RR, 15RL, the right front wheel, the left front wheel, the right rear wheel, Pressure sensors 44FR, 44FL, 44RR, 44RL for the left rear wheel are provided.

  The ECU 100 controls the master cut valves 22FR, 22FL, the on-off valve 23, the motor 32, the four pressure increasing valves 40FR, 40FL, 40RR, 40RL, and the four pressure reducing valves 42FR, 42FL, 42RR, 42RL. The ECU 100 includes an arithmetic unit using a microcomputer, a ROM that stores various control programs, and a RAM that is used as a work area for data storage and program execution.

  Although not shown in detail, the arithmetic units include pressure sensors 44FR, 44FL, 44RR, 44RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively, in the wheel cylinder 15FR of the right front wheel. The pressure signal, the pressure signal in the left front wheel wheel cylinder 15FL, the pressure signal in the right rear wheel wheel cylinder 15RR, and the pressure signal in the left rear wheel wheel cylinder 15RL are input. Further, the accumulator pressure sensor 51 receives a signal indicating the depression stroke of the brake pedal 72 from the stroke sensor 46 and a signal indicating the master cylinder hydraulic pressure from the right master pressure sensor 48FR and the left master pressure sensor 48FL. Is input with a signal indicating the accumulator pressure.

  The ROM of the ECU 100 stores a predetermined braking control flow. The calculation unit calculates the target braking force of the vehicle based on the stroke signal and the master cylinder hydraulic pressure signal, calculates the target wheel cylinder hydraulic pressure of each wheel based on the calculated target braking force, and calculates the wheel cylinder hydraulic pressure of each wheel. The pressure increasing valve 40 and the pressure reducing valve 42 are controlled so that becomes the target wheel cylinder hydraulic pressure.

  FIG. 2 is a cross-sectional view schematically showing the structure of the reservoir tank 26. Brake fluid 84 is stored in the reservoir tank 26. The upper part of the reservoir tank 26 is open to the atmosphere. Below the reservoir tank 26, a conduit 27 that leads to the master cylinder 74 and the hydraulic supply / discharge conduit 28 is provided. When the level of the brake fluid is lower than the line D at the upper end of the conduit 27, air is sucked into the hydraulic brake device through the conduit 27.

  For this reason, a lower limit line (MIN line) C is preset in the reservoir tank 26. In order to detect a decrease in the brake fluid level to the lower limit line C, a fluid level switch 80 is attached to the inner wall of the reservoir tank 26. The liquid level switch 80 is a switch that is switched from the off state to the on state when the brake liquid level becomes lower than the lower limit line C. The liquid level switch 80 can be of any type. For example, a switch of a type that detects the liquid level based on a change in pressure based on the volume of brake fluid or a change in capacitance may be used. Alternatively, a switch that detects the height of the liquid level using a float or optically detects it may be used.

  When the brake fluid is consumed and the brake fluid level falls to the lower limit line C, the fluid level switch 80 is turned on. Conventionally, when the liquid level switch 80 is turned on, an alarm lamp is lit, and control of the hydraulic brake device is stopped in order to prevent further consumption of the brake fluid. Specifically, in FIG. 1, the pressure increase valves 40FR and 40FL and the pressure reduction valves 42FR and 42FL are closed, and the right master cut valve 22FR and the left master cut valve 22FL are opened, so that the wheel from the master cylinder 74 is opened. Brake fluid is supplied to the cylinder 15. Even if the brake fluid in the reservoir tank 26 runs out, if the brake fluid remains in the master cylinder 74, a braking force can be generated by the brake pedal 72.

  However, as shown in FIG. 2, the normal lower limit line C is set slightly above the line D where air is actually sucked. That is, even if the brake fluid level is below the lower limit line C and is between the lower limit line C and the line D, no air is sucked in even if the brake control is continued. Therefore, in the present embodiment, after the liquid level falls below the lower limit line C, it is estimated how much time is left before air suction occurs, and control of the hydraulic brake device is continued during the time. I did it.

  FIG. 3 shows a state in the reservoir tank when the vehicle is suddenly accelerated or decelerated. FIG. 3A shows the liquid level in the reservoir tank when the acceleration (or deceleration) of the vehicle is relatively small. When the original liquid level is A, the liquid level in the reservoir tank 26 is tilted like B due to acceleration or deceleration of the vehicle, so that the brake liquid level is momentarily changed at the location where the liquid level switch 80 is installed. The liquid level switch 80 may be turned on. Similarly, FIG. 3B shows the liquid level in the reservoir tank when the acceleration or deceleration of the vehicle is relatively large. Similarly, when the original liquid level is A and the liquid level in the reservoir tank 26 tilts like B due to acceleration or deceleration of the vehicle, the liquid level switch 80 is turned on.

  Since the degree of inclination of the liquid level in the reservoir tank 26 varies depending on the acceleration or deceleration of the vehicle, the height of the liquid level h (the height from the lower limit line C) at which the liquid level switch 80 is turned on. Is also different. Therefore, if the magnitude of the acceleration or deceleration of the vehicle is known, the liquid level height h when the liquid level switch 80 is turned on because the liquid level in the reservoir tank 26 is shaken by the acceleration / deceleration of the vehicle is estimated. be able to. The correspondence between the acceleration / deceleration of the vehicle and the liquid level height h can be accurately obtained by experiments or the like. Thus, in this embodiment, the liquid level height h is obtained by using the acceleration / deceleration of the vehicle when the liquid level switch 80 is turned on.

FIG. 4 is a diagram showing the on / off state of the liquid level switch and the passage of time when a liquid leak occurs. In the present embodiment, the grace time is calculated as follows. When the vehicle is accelerating or decelerating and the liquid level switch 80 is first turned on (time t _{A in} FIG. 4), the vehicle is not accelerating / decelerating and the liquid level switch 80 is turned on ( A time T _m until time t _C ) in FIG. 4 is measured by a timer. The time t _A corresponds to the time when the liquid level A in FIG. 3A and FIG. 3B is inclined to the liquid level B, and the time t _C is the lower limit line C when the liquid level is flat. Corresponds to the point of decrease. Therefore, the time T _m corresponds to the time required for the brake fluid amount to decrease due to liquid leakage from the liquid level A to the lower limit line C in FIG.

As described above, based on the acceleration time t _A, it is possible to obtain the height h from the liquid surface A to the lower limit line C. Assuming that the cross-sectional area of the reservoir tank is S, the brake fluid amount W exceeding the lower limit line C is obtained by W = S · h. Therefore, the brake fluid level lowering speed v in the reservoir tank can be expressed by the following equation.
v = W / T _m (1)

Use brake fluid level dropping speed v, it is possible to estimate the delay time T _n up to the suction air. Since afford liquid amount R from the lower line C to the air suction line D are known in advance, the window time T _n can be expressed by the following equation.
T _n = R / v (2)
Thus, between the time t _C until T _n has elapsed (until a time t _D in FIG. 4), it can be determined that the brake control can be continued without causing suction air.

  FIG. 5 is a functional block diagram showing a configuration of a part related to the use time extension control of the reservoir tank according to the present embodiment. Each block shown in the ECU 100 can be realized in terms of hardware by an element or a mechanical device such as a CPU and a memory of a computer, and can be realized by a computer program or the like in terms of software. It is drawn as a functional block realized by. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The acceleration sensor 90 is installed on the vehicle body and detects vertical acceleration or horizontal acceleration of the vehicle. As described above, the liquid level switch 80 detects a decrease in the brake liquid level toward the lower limit line in the reservoir tank 26.

  The liquid level map holding unit 102 causes the brake liquid level to fall below the lower limit line C at the location where the liquid level switch 80 is installed due to the inclination of the brake liquid level in the reservoir tank 26 when the vehicle accelerates or decelerates at a certain acceleration. The height h of the liquid level is held as a map. The relationship between the acceleration of the vehicle and the liquid level height h can be obtained in advance through experiments and simulations. This acceleration may be either vertical acceleration or horizontal acceleration, or a combined value thereof.

The liquid leak estimation unit 103 receives acceleration from the acceleration sensor 90 and switch on / off information from the liquid level switch 80. When the liquid amount calculation unit 104 detects that the liquid level switch 80 is turned on when the vehicle accelerates or decelerates, the liquid level calculation unit 104 refers to the acceleration and calculates the corresponding liquid level height h from the liquid level height map holding unit 102. get. Then, by multiplying the fluid level height h by the cross-sectional area S of the reservoir tank, the brake fluid amount W = S · h that exceeds the lower limit line C at time t _A is estimated.

The timer unit 108 has elapsed time from the time t _A when the liquid level switch 80 is turned on when the vehicle is accelerated / decelerated to the time t _C when the liquid level switch 80 is turned on when the vehicle is not accelerated / decelerated. _Tm is measured.

The liquid leak estimation unit 103 receives the elapsed time T _m from the timer unit 108. Lowering speed calculation unit 106, using the time elapsed and the estimated brake fluid amount W T _m, and calculates the brake fluid surface reduction rate v. The grace time calculation unit 110 calculates a grace time T _n from the surplus fluid amount R and the brake fluid level lowering speed v.

Control stop unit 112, notifying that the liquid level switch is the grace from time t _C, which turned on the time T _n has elapsed, by lighting an alarm lamp 114 to stop the brake control for the brake fluid leak has occurred in the occupant At the same time, the control of the hydraulic brake device 200 is stopped. Specifically, the operation of the pump and various control valves is stopped, and only the brake pressure from the master cylinder 74 via the conduits 76 and 78 is operated.

FIG. 6 is a flowchart of the use time extension control of the reservoir tank according to the present embodiment.
The acceleration sensor 90 detects the acceleration of the vehicle (S10). The liquid level switch 80 detects a decrease in the brake liquid level toward the lower limit line C (S12). Unless a decrease in the brake fluid level is detected (N in S12), S10 and S12 are repeated. When a decrease in the brake fluid level is detected (Y in S12), the timer unit 108 starts measuring time (S14). The liquid amount calculation unit 104 acquires the acceleration of the vehicle when the liquid level switch is turned on. And the liquid level height h is acquired with reference to the liquid level map holding | maintenance part 102, and the liquid quantity W to the lower limit line C is estimated (S16). Subsequently, the timer unit 108 monitors the acceleration sensor 90 and the liquid level switch 80, waits for the acceleration to be 0 and the liquid level switch to be turned on (S18), and when this condition is satisfied (Y in S18). The timer unit 108 stops measuring time (S20). Thus, the measurement time _Tm is obtained. Reduction rate calculator 106 calculates a brake fluid surface reduction rate v of the liquid content W and the measurement time _{T m} (S22). The grace time calculation unit 110 calculates a grace time T _n from the brake fluid level lowering speed v and the surplus fluid amount R (S24).

As described above, according to the present embodiment, the brake fluid level lowering speed at the time of fluid leakage is estimated using the phenomenon that the fluid level switch in the reservoir tank is temporarily turned on when the vehicle is accelerated or decelerated. Then, the grace time until air inhalation occurred was calculated. Then, by continuing the brake control during the grace period, the brake control can be continued for a longer time even when the brake fails.
Further, this embodiment can be realized only by providing one liquid level switch in the reservoir tank. Since a normal reservoir tank is provided with a liquid level switch, it can be realized without adding new elements to the conventional configuration, which is advantageous in terms of cost.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  In actual driving, the vehicle repeatedly accelerates and decelerates. Therefore, it is considered that the liquid level in the reservoir tank is shaken each time and the liquid level switch is frequently turned on and off several times. In this case, when the liquid level switch is turned on for the first time, the brake liquid level lowering speed is estimated, and subsequent on / off of the liquid level switch until the liquid level switch is turned on at an acceleration of 0 is ignored. Good. Alternatively, each time the fluid level switch is turned on by acceleration / deceleration, the brake fluid level lowering speed may be estimated and an average of these may be taken. Or you may estimate a more exact speed from the change tendency of a brake fluid level fall speed.

It is a figure which shows the structure of a hydraulic brake device. It is a typical sectional view of a reservoir tank. (A), (b) is a figure which shows the mode of the liquid level in a reservoir tank when a vehicle accelerates or decelerates suddenly. It is a figure which shows the on-off state of liquid level switch at the time of liquid leak generation | occurrence | production, and time passage. It is a functional block diagram which shows the structure of the part which concerns on the use time extension control of the reservoir tank which concerns on this embodiment. It is a flowchart of use time extension control of the reservoir tank concerning this embodiment.

Explanation of symbols

  26 Reservoir tank, 80 Liquid level switch, 90 Acceleration sensor, 100 ECU, 102 Liquid level height map holding unit, 103 Liquid leak estimation unit, 104 Liquid amount calculation unit, 106 Deceleration rate calculation unit, 108 Timer unit, 110 Grace time A calculation unit, 112 a control stop unit, 114 an alarm lamp, 200 a hydraulic brake device;

Claims (4)

In a hydraulic brake device that supplies brake fluid from a reservoir tank through a conduit to generate braking force on the vehicle,
An acceleration sensor for detecting acceleration generated in the vehicle;
A liquid level switch for detecting a decrease in brake fluid level to a predetermined lower limit fluid level of the reservoir tank;
A liquid level map holding unit for holding the liquid level from the lower limit liquid level when the brake liquid level is lowered below the liquid level switch due to the inclination of the brake liquid level in the reservoir tank during acceleration / deceleration of the vehicle; ,
From the first time when the liquid level switch detects a decrease in the brake liquid level due to the inclination of the liquid level in the reservoir tank, the liquid level switch is braked when the vehicle is not accelerating / decelerating and the brake liquid level is horizontal. A timer unit for measuring an elapsed time until the second time for detecting a drop in the liquid level;
Liquid that obtains the corresponding liquid level from the liquid level map holding unit with reference to the acceleration of the vehicle at the first time, and calculates the brake liquid level lowering speed from the elapsed time and the liquid level A leak estimator;
A grace time calculating unit for calculating a grace time until the control of the device is stopped based on the brake fluid level lowering speed;
A hydraulic brake device comprising:   The liquid leakage estimation unit calculates the remaining amount of brake fluid up to the lower limit liquid level at the first time based on the liquid level height and the cross-sectional area of the reservoir tank, and based on the remaining liquid amount and the elapsed time, The hydraulic brake device according to claim 1, wherein a brake fluid level lowering speed is calculated. The fluid level switch is arranged at a position where there is a surplus fluid amount from when the brake fluid level reaches the lower limit fluid level until air suction into the conduit occurs.
3. The liquid according to claim 2, wherein the grace time calculation unit calculates a grace time until the brake fluid level decreases to a conduit outlet based on the brake fluid level lowering speed and the marginal fluid amount. Pressure brake device. A hydraulic brake provided with a fluid level switch for supplying brake fluid from a reservoir tank through a conduit to generate braking force on the vehicle and detecting a decrease in the brake fluid level to a predetermined lower limit fluid level of the reservoir tank In the device
The liquid level height from the lower limit liquid level when the brake liquid level falls below the liquid level switch due to the inclination of the brake liquid level in the reservoir tank during acceleration / deceleration of the vehicle is stored in the memory in advance.
From the first time when the liquid level switch detects a decrease in the brake liquid level due to the inclination of the liquid level in the reservoir tank, the liquid level switch is operated when the vehicle is not accelerating / decelerating and the brake liquid level is horizontal. Measure the elapsed time up to the second time to detect the surface drop,
Obtaining the corresponding liquid level height from the liquid level map holding unit with reference to the acceleration of the vehicle at the first time,
Calculate the brake fluid level lowering speed from the elapsed time and the fluid level height,
Calculate the grace time until the control of the hydraulic brake device is stopped based on the brake fluid level lowering speed,
A control method of a hydraulic brake device, wherein the control of the hydraulic brake device is stopped when the grace time has elapsed from the second time.

Images