JP2002029405A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress excessive surge pressure of a brake cylinder caused by abnormality of a power type hydraulic pressure source in a brake device including a brake being operated by operating fluid being outputted from the power type hydraulic pressure source. SOLUTION: When the continuous operating time of a pump device is a set time or more and the output hydraulic pressure is a set pressure or more, the pump device is regarded to be in an excessive pressurization state (S1, 2 and 5) so that a decompression linear valve is changed over into an open state (S6). The operating fluid being outputted from the pump device and the operating fluid of the brake cylinder are made to flow out to a reservoir via the decompression linear valve so as to suppress the excessive surge pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device including a brake which is operated by supplying hydraulic fluid output from a power hydraulic pressure source to a brake cylinder.

[0002]

2. Description of the Related Art An example of a brake device provided with the above-mentioned power type hydraulic pressure source is described in Japanese Patent Application Laid-Open No. 10-86804. The brake device described in this publication includes (a) a power-operated hydraulic pressure source that is actuated by power and pressurizes and outputs hydraulic fluid, and (b) a hydraulic fluid output from the power-operated hydraulic pressure source. A brake operated by being supplied to the cylinder, and (c) an outflow prevention state provided between the brake cylinder and the low pressure source to prevent the flow of hydraulic fluid from the brake cylinder to the low pressure source; (D) when the hydraulic pressure of the brake cylinder is higher than the set pressure and the brake operating member is not operated, and an open valve that can be switched to an outflow allowable state that allows the flow of hydraulic fluid to the low pressure source. Includes an overpressure suppression device that switches the release valve to the outflow allowable state. If the release valve is switched to the outflow allowable state, it is possible to suppress the hydraulic pressure of the brake cylinder from being excessively increased.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to suppress an excessive increase in the hydraulic pressure of a brake cylinder in a manner different from the case of the brake device described in the above publication. is there. This problem is solved by providing the brake device having the following configurations. Each mode is described in the same manner as in the claims, divided into sections, each section is numbered, and described in the form of citing the numbers of other sections as necessary. This is to facilitate understanding of the present invention, and the technical features and combinations thereof described in this specification should not be construed as being limited to the following sections. Further, when a plurality of items are described in one section, not all items must always be adopted together, but it is also possible to take out and adopt only some items. (1) A power hydraulic pressure source which is activated by power and pressurizes and outputs hydraulic fluid, and a brake which is activated by supplying hydraulic fluid output from the power hydraulic pressure source to a brake cylinder. An over-pressurization detecting device for detecting that the power type hydraulic pressure source is in an over-pressurized state, and when the power type hydraulic pressure source is detected to be in an over-pressurized state by the over-pressure detecting device. An overpressure suppression device for suppressing an overpressure of the hydraulic pressure of the brake cylinder (claim 1). In the brake device described in this section, when it is detected that the power type hydraulic pressure source is in the over-pressurized state, the excessive increase in the hydraulic pressure of the brake cylinder is suppressed. It is not suppressed when it is detected that the actual hydraulic pressure of the brake cylinder has exceeded the set pressure. Therefore, for example, before the hydraulic pressure of the brake cylinder actually increases, that is, before it is possible, it is possible to suppress excessive pressure increase, and it is possible to suppress the driver's discomfort. The excessive pressure increase means that the brake fluid pressure becomes higher than the required brake fluid pressure, for example, it becomes higher than the required brake fluid pressure intended by the driver. Therefore, when the required brake fluid pressure is 0 (during non-braking operation) and the hydraulic fluid is supplied to generate the brake fluid pressure, even if the fluid pressure itself is not so high, it is considered that the pressure has been excessively increased. I do. (2) The power type hydraulic pressure source includes a pump that pressurizes and discharges hydraulic fluid, and an electric motor that drives the pump.
The brake device according to (1). The pump is operated by driving the electric motor, and the hydraulic fluid is pressurized and discharged. If the supply current to the electric motor is controlled, the operation state of the pump is controlled, and the discharge state of the working fluid is controlled. The current supplied to the electric motor is controlled by switching control of a drive circuit and a relay. In this case, for example,
If an abnormality occurs in the drive circuit or the relay, the supply current to the electric motor cannot be controlled, and the current may be continuously supplied. The pump is continuously driven by the electric motor, and the power hydraulic pressure source may be in an over-pressurized state. The pump may be a gear pump or a plunger pump. (3) The brake device according to (2), wherein the power-type hydraulic pressure source includes an accumulator that stores the hydraulic fluid discharged from the pump. The working fluid discharged from the pump is stored in an accumulator. The electric motor is operated so that the hydraulic pressure of the working fluid stored in the accumulator is maintained within a set range.
It is usually controlled. For example, if an abnormality occurs in the above-described drive circuit or relay, the pump may continue to be driven even if the accumulator pressure exceeds the upper limit of the set range. This also occurs when an abnormality occurs in the sensor that detects the accumulator pressure. (4) The brake device according to any one of the above items (1) to (3), wherein the overpressure suppression device includes an output reduction unit that reduces an output hydraulic pressure of a power hydraulic pressure source. If the output hydraulic pressure of the power hydraulic pressure source is reduced, it is possible to suppress over-pressurization of the brake cylinder. For example, it is possible to prevent the hydraulic fluid from being supplied to the pump, stop the operation of the pump, or operate the pump under reduced pressure. An electromagnetic control valve is provided between the suction side of the pump and the hydraulic fluid tank so as to be able to switch between a communication state in which they are communicated and a shut-off state in which they are shut off. In this case, if the electromagnetic control valve is closed, the hydraulic fluid is not supplied to the pump, and the discharge pressure can be reduced.
Also, by outputting a stop command to stop the operation of the electric motor to a drive circuit or a relay that controls the electric motor, or outputting a reverse rotation command to rotate in the opposite direction, the rotation of the electric motor can be stopped, It can be rotated in the opposite direction. In the latter case, as described in item (3), when the electric motor is controlled based on the value detected by the accumulator pressure sensor so that the accumulator pressure is within a predetermined set range, the driving circuit This is effective when the power source and the relay are normal and the power hydraulic pressure source is in an overpressurized state due to an abnormality of the accumulator pressure sensor. Since the drive circuit, the relay, and the like are normal, the electric motor can be controlled by directly controlling the drive circuit, the relay, and the like (ie, not based on the value detected by the accumulator pressure sensor). (5) The brake device according to (4), wherein the output reduction unit includes a pressurizing operation stopping unit that stops pressurizing operation of the power hydraulic pressure source. (6) The brake device according to the mode (4) or (5), wherein the output reduction section includes a pressure reducing operation section that performs a pressure reducing operation on the power type hydraulic pressure source. When the power type hydraulic pressure source includes a gear pump and allows the flow of the hydraulic fluid discharged from the pump on the discharge side of the gear pump, but is not provided with a check valve for preventing reverse flow, By rotating the gear pump in the opposite direction, the discharge pressure can be reduced. (7) The brake device is provided between the brake cylinder and the low-pressure source, and an outflow preventing state in which the flow of the hydraulic fluid from the brake cylinder to the low-pressure source is prevented; The overpressure suppression device includes an open valve that switches the open valve to the outflow allowable state. The brake device according to any one of the above. If the release valve is switched to the outflow permission state, the hydraulic fluid of the brake cylinder and the hydraulic fluid of the power type hydraulic pressure source can be discharged to the low pressure source through the release valve, so that the hydraulic pressure of the brake cylinder is excessively increased. Can be suppressed. The opening valve may be a linear control valve that controls the difference between the front and rear hydraulic pressures to a size corresponding to the supply current, or an opening / closing valve that is opened and closed by turning on / off the supply current. (8) The brake device according to the above mode (7), wherein the overpressure suppressing device sets the release valve to an outflow allowable state while the brake is not operated. (9) The brake device is provided corresponding to one or more brake cylinders, and the hydraulic pressure of the one or more brake cylinders can be controlled using the hydraulic fluid of the power hydraulic pressure source. The brake device according to the mode (7) or (8), further including a hydraulic control valve device, wherein the release valve is included in the individual hydraulic control valve device. The hydraulic pressure of the brake cylinder is controlled by controlling the individual hydraulic pressure control valve device. When the brake is operated by supplying hydraulic fluid from a power hydraulic pressure source to the brake cylinder, an individual hydraulic pressure control valve device capable of controlling the hydraulic pressure of the brake cylinder is necessary.
The release valve is one component of the individual hydraulic pressure control valve device, and can be, for example, a control valve for reducing pressure. The individual hydraulic control valve device may be provided corresponding to each of the brake cylinders, or may be provided commonly to two or more brake cylinders. The individual hydraulic pressure control valve device may include the above-described pressure reducing control valve (opening valve) and a pressure increasing control valve provided between the power type hydraulic pressure source and the brake cylinder, or may include a pressure increasing control valve. A control valve for reducing pressure may be included without including a valve. If the power type hydraulic pressure source can control the output hydraulic pressure, the control valve for increasing the pressure is not indispensable. (10) The overpressure suppression device sets the release valve to the outflow permitting state until the actual brake fluid pressure reaches the required brake fluid pressure during the brake operation, according to any one of (7) to (9). The brake device according to any one of the preceding claims. In the brake device described in this section, the opening valve is controlled so that the actual brake fluid pressure does not become higher than the required brake fluid pressure. The required brake fluid pressure can be acquired, for example, based on the operation state of the brake operation member. In other words, the hydraulic pressure of the brake cylinder is controlled by the control of the release valve. In this case, the release valve is also regarded as one component of the individual hydraulic pressure control valve device that controls the hydraulic pressure of the brake cylinder. Can be. (11) A relief valve that switches from a closed state to an open state when the discharge pressure of the pump becomes equal to or higher than a predetermined set pressure, and allows the hydraulic fluid discharged from the pump to flow to the low pressure side. The brake device according to any one of the above modes (7) to (10), which does not include the following. In the brake device described in this section, the release valve is opened when the power hydraulic pressure source is in the over-pressurized state, so that an excessive load is applied to the pump without providing a relief valve. Can be avoided. (12) The over-pressurization detecting device determines that the continuous pressurizing operation time of the power hydraulic pressure source has exceeded the set time and that the output hydraulic pressure of the power hydraulic pressure source has exceeded the set pressure. The brake device according to any one of the paragraphs (1) to (11), wherein the power hydraulic pressure source is in an over-pressurized state when at least one of them is satisfied. An embodiment which depends on any one of the above items (11) to (11)). If the continuous operation time of the power hydraulic pressure source exceeds the set time or if the output hydraulic pressure exceeds the set pressure, it is determined that the over-pressurizing condition is satisfied and the over-pressurizing state is established. The over-pressurizing condition is desirably set by paying attention to whether the hydraulic pressure of the brake cylinder is over-pressurized or not, but is not limited thereto. For example, an abnormality that is set by paying attention to whether or not the load of the power hydraulic pressure source becomes excessive or that there is a possibility of becoming excessive, or that causes the power hydraulic pressure source to become overpressurized It can be set by paying attention to whether or not an error has occurred or whether or not there is a possibility that an abnormality may occur. The set time can be, for example, a time during which the power-operated hydraulic pressure source cannot operate continuously for a longer time if it is normal. Specifically, as described in item (3), when the electric motor that drives the pump is controlled such that the accumulator pressure is kept within a set range,
The time required to increase the accumulator pressure from the lower limit value to the upper limit value of the set range or a slightly longer time can be used. The set pressure is, for example, a hydraulic pressure at which a hydraulic fluid having a higher hydraulic pressure should not be discharged if the power hydraulic pressure source is normal, or a higher hydraulic pressure in controlling the brake cylinder hydraulic pressure. When the hydraulic fluid is discharged, the hydraulic pressure may be excessively increased. Specifically, in the former case, the upper limit of the setting range of the accumulator pressure described above or a value slightly higher than the upper limit can be set. In the latter case, it can be set to a value based on the valve opening pressure of an electromagnetic control valve provided between the power hydraulic pressure source and the brake cylinder. An example is as follows. Powered hydraulic pressure source
Including the accumulator according to paragraph (3), the brake device includes the individual hydraulic pressure control valve device according to paragraph (10), and the individual hydraulic pressure control valve device includes a power type hydraulic pressure source and a brake. It may include a normally-closed pressure-increasing control valve that is provided between a cylinder and a valve that opens and closes based on a differential pressure between the front and rear. The normally-closed pressure-increasing control valve is kept closed as long as no current is supplied to the coil, and when the current is not supplied to the coil, the hydraulic fluid is often not supplied to the brake cylinder. In this case, if a high-pressure hydraulic pressure is applied to the pressure-increasing control valve due to an abnormality of the power-type hydraulic pressure source, the pressure-increasing control valve is opened even if current is not supplied to the coil, and the brake cylinder is opened. The working fluid is caused to flow into the air. Therefore, the set pressure is determined based on the valve opening pressure, for example, by setting the pressure slightly lower than the valve opening pressure of the pressure increasing control valve. The pressure increase is suppressed. (13) When the output pressure of the power type hydraulic pressure source exceeds a set pressure determined based on the temperature of the hydraulic fluid, the power type hydraulic pressure source may overpressurize the power type hydraulic pressure source. The brake device according to any one of the above aspects (1) to (12), including a liquid temperature-responsive over-pressurization detection unit that is in a state. As described in [Embodiment of the invention], the brake device may be a device having a configuration that allows the hydraulic fluid of the power type hydraulic pressure source to flow to a low pressure source other than the brake cylinder during non-braking operation. is there. When the hydraulic fluid is near normal temperature and has low viscosity (normal height), the hydraulic fluid of the power hydraulic pressure source is quickly discharged to the low pressure source,
The brake cylinder fluid pressure will not be excessively increased. Even if the hydraulic fluid flows into the brake cylinder, the hydraulic pressure of the brake cylinder does not become so high as to cause a problem in running. On the other hand, when the hydraulic fluid is low in temperature and high in viscosity, it becomes difficult for the hydraulic fluid of the power type hydraulic pressure source to flow out to the low pressure source, and accordingly, the hydraulic pressure of the brake cylinder increases. The brake fluid pressure may be over-boosted and become so high that the fluid pressure becomes a driving problem. Therefore, when the hydraulic fluid temperature is low, the set pressure is set lower than when it is high, and even if the hydraulic fluid temperature is low and the viscosity increases, the excessive increase in the brake cylinder hydraulic pressure is suppressed. is there. The set pressure may be changed continuously with respect to a change in the temperature of the working fluid, or may be changed stepwise. For example, when the temperature is equal to or lower than the temperature at which the viscosity increases, the set pressure is reduced. (14) The release valve is provided corresponding to each of the two brake cylinders connected by a communication passage, and the overpressure suppression device is configured such that the overpressure suppression device corresponds to one of the two brake cylinders. A first decompression state in which the release valve is set to an outflow permitting state and a second opening valve corresponding to the other brake cylinder is set to an outflow prevention state; and the second opening is performed while the first opening valve is set to an outflow prevention state. The brake device according to any one of (7) to (13), further including an alternate opening control unit that causes the valve to alternately appear in a second depressurized state in which the valve is allowed to flow out. When two brake cylinders are connected to each other by a communication passage as in the brake device described in this section, the first release valve and the second
If one of the release valves is set in the outflow allowable state, the outflow of the hydraulic fluid from both brake cylinders is allowed.
In the case where the first and second opening valves are switched to the outflow permitting state by supplying current, the first and second opening valves are switched to the first and second opening valves.
If the open valve and the second open valve are alternately switched to the outflow permitting state, the amount of heat generated in one open valve can be suppressed as compared with the case where both are switched to the outflow permitting state. Power consumption can be reduced. (15) The communication path connecting the two brake cylinders is provided with a communication valve that is switched between a flow permitting state in which the flow of the hydraulic fluid in the communication path is permitted and a flow blocking state in which the flow of the hydraulic fluid is blocked. 14) The brake device according to the above item.
If a communication valve is provided in the communication passage, it is possible to switch between a common control state in which the two brake cylinders are commonly controlled and an independent control state in which the two brake cylinders are independently controlled. Switching to the independent control state is effective in antilock control and vehicle stability control. (16) The brake device according to the mode (15), wherein the communication valve is switched to a flow permission state when the power type hydraulic pressure source is detected to be in an overpressurized state. As will be described in [Embodiment of the invention], it is desirable that the communication valve can be switched to the flow permission state when the power type hydraulic pressure source is abnormal or when the electric system is abnormal. Therefore, even if the hydraulic pressures of the two brake cylinders become uncontrollable, the hydraulic pressures of the two brake cylinders can be made equal. It is desirable that the communication valve be kept in a flow permitting state during the non-braking operation. (17) A power type hydraulic pressure source which is operated by power to pressurize and output hydraulic fluid, an over-pressure detecting device for detecting that the power type hydraulic pressure source is in an over-pressurized state, An overload suppression device that suppresses a load applied to the power hydraulic pressure source when the power hydraulic pressure source is detected by the pressurization detection device to be in an overpressurized state. Hydraulic pressure source device. The technical features described in any of the above modes (1) to (16) can be employed in the power hydraulic pressure source device described in this mode. (18) A power type hydraulic pressure source which is operated by power and pressurizes and outputs hydraulic fluid, an over-pressure detecting device which detects that the power type hydraulic pressure source is in an over-pressurized state, An opening device for communicating the power type hydraulic pressure source to a low pressure source when the power type hydraulic pressure source is detected to be in an over-pressurized state by a pressure detection device. Source equipment.
(1) to (16)
The technical features described in any of the items can be adopted.

[0004]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a brake device according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the brake device is provided on a brake pedal 10 as a brake operating member, a pump device 12 as a power type hydraulic pressure source, a master cylinder 14 with a hydro booster, and left and right front wheels 16 and 17. Brake 20, 21 including brake cylinders 18, 19, and brake cylinders 26, 27 provided on left and right rear wheels 24, 25
And brakes 28 and 29 including.

The pump device 12 includes a pump 30, a pump motor 32 for driving the pump 30, and an accumulator. The pump 30 pressurizes and discharges the hydraulic fluid in the reservoir 36, and the high-pressure hydraulic fluid discharged from the pump 30 is stored in the accumulator 34.
The hydraulic pressure of the accumulator 34 is the accumulator pressure sensor 3
8, the pump motor 32 is controlled so that the hydraulic pressure detected by the accumulator pressure sensor 38 is maintained within a predetermined set range. On the discharge pressure side of the pump 30, a check valve 39 for preventing the backflow of the hydraulic fluid to the pump 30 is provided. The pump 30
May be a plunger pump or a gear pump.

[0006] Master cylinder 14 with hydro booster
Includes a hydraulic booster 40 having a hydraulic adjustment section and a master cylinder 42 having a pressurizing piston. In the hydraulic pressure adjusting section of the hydraulic booster 40, the hydraulic pressure of the pump device 12 is adjusted to a height corresponding to the brake operating force. The operating force applied to the brake pedal 10 (the output of the vacuum booster when a vacuum booster is provided) and the force corresponding to the hydraulic pressure of the hydraulic pressure booster 40 are applied to the pressurizing piston of the master cylinder 42. In addition, a hydraulic pressure corresponding to the resultant force is generated in the pressurizing chamber 43. The hydraulic fluid of the hydraulic booster 40 is supplied to the brake cylinder 26 of the left rear wheel 24 via a hydraulic passage 44, and the hydraulic fluid of the pressurizing chamber 43 of the master cylinder 42 is supplied to the brake cylinder of the left front wheel 16 via a hydraulic passage 46. 18.

In the middle of the liquid passages 44 and 46, master shutoff valves 50 and 52 are provided, respectively. The brake cylinders 18 and 19 of the left and right front wheels 16 and 17 and the brake cylinders 26 and 27 of the left and right rear wheels 24 and 25 are connected by communication passages 54 and 56, respectively. , Communication valves 58 and 60 are provided. Master shutoff valves 50 and 52 are normally open valves that are open when current is not supplied to coil 62, and communication valves 58 and 60 are normally open valves that are open when no current is supplied to coil 64. is there.

A simulation device 66 is provided in a portion of the liquid passage 46 upstream of the master shutoff valve 52. The simulation device 66 includes a stroke simulator 67 and a stroke simulator opening / closing valve 68. The stroke simulator 67 is connected to the liquid passage 46 via the stroke simulator opening / closing valve 68. On-off valve 68 for stroke simulator
Is a normally closed valve that is closed when no current is supplied to the coil 69.

The pump device 12 is connected to the hydraulic booster 40 via a liquid passage 70 and a liquid passage 72.
All brake cylinders 18, 19, 26,
27. Also, the brake cylinders 18 and 1
Each of 9, 26 and 27 is provided with a linear valve device 80 to 86 as an individual hydraulic pressure control valve device. Each of the linear valve devices 80 to 86 includes a pressure-increasing linear valve 90 and a pressure-reducing linear valve 92.
2, a pressure reducing linear valve 92 is provided in a liquid passage 94 connecting the brake cylinders 18, 19, 26, 27 and the reservoir 36. The pressure reducing linear valve 90 is the opening valve in the present embodiment. The brake cylinders 18, 1 are controlled by the linear valve devices 80 to 86.
The hydraulic pressures of 9, 26 and 27 are controlled using the hydraulic fluid of the pump device 12.

As shown in FIG. 2, the pressure-increasing linear valve 90 and the pressure-decreasing linear valve 92 are normally closed valves, and a solenoid 102 including a coil 100 and a valve
4 and a seating valve 110 including a valve seat 106 and a spring 108. In the seating valve 110, the urging force of the spring 108 acts in a direction in which the valve 104 is seated on the valve seat 106, and the valve 104
Is acted on in the direction of separating the valve from the valve seat 106 and an electromagnetic driving force corresponding to the amount of current supplied to the coil 100 according to the hydraulic pressure difference before and after the linear valve. Coil 10
When the differential pressure acting force is smaller than the biasing force of the spring 108 while the current is not supplied to the valve
06, the closed state is maintained, but when the differential pressure acting force becomes larger than the urging force, the valve element 104 is separated from the valve seat 106. When current is supplied to the coil 100, the relative position of the valve element 104 with respect to the valve seat 106 is determined by the relationship between the electromagnetic driving force, the urging force of the spring 108, and the differential pressure acting force. It will be controlled by the control.

The differential pressure acting force applied to the pressure increasing linear valve 90 is a force corresponding to the differential pressure between the hydraulic pressure of the pump device 12 (the hydraulic pressure of the accumulator) and the brake cylinder hydraulic pressure. Is a force corresponding to the differential pressure between the brake cylinder fluid pressure and the master reservoir fluid pressure. Since the master reservoir fluid pressure is approximately atmospheric pressure, the brake cylinder fluid pressure Depending on the power. In any case, if the electromagnetic driving force is controlled (the current supplied to the coil 100 is controlled), the hydraulic pressure of the brake cylinder can be controlled.

The pressure-increasing linear valve 9 in the liquid passage 72
A hydraulic pressure sensor 120 is provided between 0 and the pump device 12. The hydraulic pressure of the hydraulic fluid on the high pressure side of the pressure increasing linear valve 90 is detected by the hydraulic pressure sensor 120. The hydraulic pressure sensor 1 is used as the hydraulic pressure on the high pressure side of the pressure increasing linear valve 90.
If the value detected by the accumulator pressure sensor 38 is used, the influence of the pressure loss between the pump device 12 and the pressure-increasing linear valve 90 can be eliminated. Valve device 80-86
Control accuracy can be improved.

The present hydraulic brake device is controlled by a brake hydraulic pressure control device 150. As shown in FIG. 3, the brake fluid pressure control device 150 includes a CPU 152, a ROM 1
54, RAM 156, input unit 157 and output unit 158
And the like. The input unit 157 includes, in addition to the accumulator pressure sensor 38 and the hydraulic pressure sensor 120 described above, hydraulic pressure sensors 160 and 162 for detecting hydraulic pressures in the fluid passages 44 and 46, and brake cylinders 18, 19, 26 and 27, respectively. Brake fluid pressure sensors 164 to 167 for detecting fluid pressures, wheels 16, 1
Wheel speed sensors 169 to 172 for detecting wheel speeds of wheels 7, 24 and 25, stroke sensors 174 and 175 for detecting a stroke of the brake pedal 10, and a brake switch 176 for detecting whether or not the brake pedal 10 is in an operating state. , Temperature sensor 1 for detecting the temperature of hydraulic fluid
78, a current detecting device 179 for detecting whether or not current is actually flowing through the pump motor 32, and the like are connected.
The output section 158 has a pump motor 32 connected to the drive circuit 180.
And the linear valve devices 80 to
86 coils 100, the respective solenoid on-off valves 50, 52, 58,
60 and 68 coils are driving circuits 182 and 184, respectively.
Connected via The ROM 154 stores a brake fluid pressure control program represented by the flowchart of FIG.
A plurality of programs and tables, such as a linear valve device control program, are stored.

As described above, in the present hydraulic brake device, two stroke sensors for detecting the stroke of the brake pedal 10 are provided (174, 17).
5). Further, two hydraulic pressure sensors for detecting a hydraulic pressure (master pressure) corresponding to the operating force are also provided (160, 16).
2). It is not indispensable to provide these two by two, but if two are provided, it is possible to use the detection value of the other when an abnormality occurs in one, which is effective in fail-safe. The required brake fluid pressure intended by the driver is obtained based on both the stroke of the brake pedal 10 and the operating force. In the present embodiment, the average value S of the detection values of the two stroke sensors 174 and 175 is obtained.
The required brake fluid pressure PWC ^* is determined based on the average value F of the detection values of the two fluid pressure sensors 160 and 162.
For example, the required brake fluid pressure PWC ^* can be determined according to the following equation: PWC ^* = S.gamma ^. (S) + F. (1-.gamma. (S)). Here, γ (s) is a positive value smaller than 1, and is a value that increases as the stroke becomes smaller. In order to obtain the required braking torque,
Providing these four sensors is not essential. 4
It is also possible to provide a treading force sensor instead of the two sensors, and to obtain the treading force based on the value detected by the treading force sensor. Further, the temperature sensor 178 may directly detect the temperature of the working fluid or may indirectly detect the temperature. A device that detects the temperature outside the liquid passage or a device that detects the outside air temperature may be used. Based on these, the temperature of the working fluid can be estimated.

The operation of the hydraulic brake device configured as described above will be described. During normal braking, the brake cylinders 18, 19, 26, 27 are shut off from the master cylinder 14 with the hydro booster by closing the master shutoff valves 50, 52. In addition, the communication valves 58 and 60 are closed, and the stroke simulator on-off valve 68 is opened. In this state, the hydraulic pressure of the brake cylinders 18, 19, 26, and 27 is increased by using the hydraulic fluid of the pump device 12 and the linear valve device 80.
The control is performed by controlling the supply current to the coils 100 to 86. Since the stroke simulator 67 is connected to the pressurizing chamber 43, the brake pedal 1
A stroke corresponding to the operation force applied to 0 can be generated.

If an abnormality occurs in the pump device 12 or the electric system, each electromagnetic control valve is returned to the original position shown in FIG. 1 in principle. Since the master shutoff valves 50 and 52 are opened and the communication valves 58 and 60 are opened, the brake cylinders 18, 19, 26 and 27 are connected to the master cylinder 14 with the hydro booster. In addition, since the stroke simulator opening / closing valve 68 is closed, the stroke simulator 66 is shut off from the master cylinder 42, thereby avoiding wasteful consumption of the hydraulic fluid. Further, since no current is supplied to each coil 100 of the linear valve devices 80 to 86, the pressure increasing linear valve 90,
The pressure reducing linear valves 92 are all closed, and the brake cylinders 18, 19, 26, 27 are shut off from both the pump device 12 and the reservoir 36. If the pump device 12 is abnormal and the output hydraulic pressure is low (for example, if the high-pressure hydraulic fluid is not stored in the accumulator 34), the master cylinder 14 with the hydro booster
Is no longer supplied with high-pressure hydraulic fluid. Hydraulic booster 4
However, the master cylinder 14 with the hydro booster operates as a simple master cylinder. The pressurizing piston is advanced with the operation of the brake pedal 10, and a hydraulic pressure corresponding to the operating force is generated in the pressurizing chamber 43. The hydraulic fluid in the pressurizing chamber 43 is supplied to the brake cylinders 18 and 19 on the front wheel side, and the brakes 20 and 21 are operated.

On the other hand, the output hydraulic pressure of the pump device 12 may increase due to the abnormality of the pump device 12. For example, if an abnormality occurs in the drive circuit 180, the pump motor 32 cannot be stopped, and the pump 30
Is operated continuously, the accumulator pressure becomes excessive,
The output hydraulic pressure increases. In the present embodiment,
The continuous operation time of the pump motor 32 is longer than the set time,
When the output hydraulic pressure is equal to or higher than the set pressure, the pump device 12 is assumed to be in an over-pressurized state. The continuous operation time is measured by a timer provided in the brake fluid pressure control device 150 based on the state of the current detected by the current detection device 179. When the pump device 12 is normal, the set time is set to an unusually long time. In the present embodiment, the accumulator pressure is set to a time slightly longer than the time required to increase the accumulator pressure from the lower limit to the upper limit of the set range.

The set pressure is determined based on the valve opening pressure of the pressure increasing linear valve 90 and the temperature of the hydraulic fluid. The determination is made by paying attention to whether or not the hydraulic pressure of the brake cylinder may be excessively increased. The pressure-increasing linear valve 90
Even if the brake fluid pressure is approximately atmospheric pressure, the accumulator pressure is a value slightly higher than the upper limit of the set range, and the differential pressure acting force is large, the seating is performed while no current is supplied to the coil 100. The valve 110 is not switched to the open state. Spring 10
The urging force 8 is set to a value larger than the differential pressure acting force applied when the accumulator pressure is slightly higher than the upper limit of the set range. However, when the output hydraulic pressure becomes excessive due to the abnormality of the pump device 12 and the differential pressure acting force becomes larger than the urging force of the spring 108, the coil 10
Even when the current is not supplied to 0, the seating valve 110 may be switched to the open state.

In this case, when the brake pedal 10 is not operated, no hydraulic pressure is generated in the master cylinder 14 with the hydro booster, and the master shut-off valves 50 and 52 are open. Therefore, even if the seating valve 110 of the pressure-increasing linear valve 90 is opened, the hydraulic fluid of the pump device 12 does not discharge the master shut-off valve 50,
Since the fluid is immediately discharged to the master cylinder 14 with the hydro booster via the valve 52, the brake cylinder hydraulic pressure is not excessively increased. Brake cylinder 18,1
Even if the hydraulic fluid flows into 9, 26 and 27, the hydraulic pressure is not so great as to cause a problem in running. On the other hand,
When the temperature of the hydraulic fluid is low, the viscosity becomes high, so that it becomes difficult for the hydraulic fluid to flow out to the master cylinder 14 with the hydro booster, and the brake cylinders 18, 19, 2 are accordingly reduced.
A large amount of hydraulic fluid flows into 6, 27. The brake fluid pressure may be excessively increased, and the fluid pressure may be high enough to be a driving problem.

Therefore, in this embodiment, as shown in FIG. 7, when the temperature of the working fluid is low, the set pressure is set lower than when it is high. Also, the viscosity of the hydraulic fluid becomes so high that it becomes problematic when the temperature becomes considerably low (for example,
About -20 °). Therefore, above normal temperature, the set pressure is a constant value, and when the temperature is low,
The set pressure is reduced as the temperature decreases.

In the present embodiment, the brake fluid pressure control program represented by the flowchart of FIG. 4 is executed for each wheel at predetermined set times. The pressure-reducing linear valves 92 provided for each wheel are controlled separately and independently, and the brake cylinders 18, 19, 26,
The hydraulic pressure of 27 is detected by brake hydraulic pressure sensors 164 to 167 detected for each brake cylinder. In step 1 (hereinafter abbreviated as S1; the same applies to other steps), it is determined whether or not the drive circuit 180 of the pump motor 32 has an ON failure. In S2, continuous energization of the pump motor 32 is performed. It is determined whether the time TM has exceeded the set time TMS. In S3, the temperature T of the hydraulic fluid is read, and in S4, the set pressure PAS is determined according to the table of FIG. Then, in S5, it is determined whether or not the actual accumulator pressure is equal to or higher than the set pressure PAS. If the determinations in S1, S2, and S5 are all YES, it is determined that the pump device 12 is in an overpressurized state. In the pressure increasing linear valve 90,
The seating valve 110 is switched to the open state even when no current is supplied to the coil 100, and the hydraulic pressure of the brake cylinder is excessively increased by the hydraulic fluid supplied from the pump device 12 via the pressure increasing linear valve 90. There is a risk. As a result, in S6, control for suppressing an excessive increase in brake fluid pressure is performed. On the other hand, when it is determined that the pump device 12 is not in the over-pressurized state, S7
In, normal control is performed.

In the normal control, as shown in the flowchart of FIG. 5, in S11, whether or not the brake is being operated is detected based on the state of the brake switch 176. If the brake is not being operated, S12
At, all solenoid valves are returned to their original positions. No current is supplied to the coils of all solenoid valves. When the brake is being operated, the linear valve devices 80 to 8 are controlled so that the required brake fluid pressure intended by the driver is obtained.
6 is controlled. In S13 and S14, the required brake fluid pressure PWC ^* is determined as described above, and in S15,
The supply current to the linear valve devices 80 to 86 is determined. For example, when the required brake fluid pressure PWC ^* is increasing, the pressure-increasing linear valve 90 is controlled (current is supplied to the coil 100), and when the required brake fluid pressure PWC ^* is decreasing, The pressure reducing linear valve 92 is controlled.

In the overpressure suppression control, as shown in the flowchart of FIG. 6, it is detected in S21 whether or not the brake is being operated. If the brake operation is not being performed, the pressure reducing linear valve 92 is opened in S22. When a current is supplied to the coil 100, the seating valve 110 is opened. The hydraulic fluid supplied to the brake cylinders 18, 19, 26, and 27 or the hydraulic fluid supplied through the pressure-increasing linear valve 90 is returned to the reservoir 36 through the pressure-reducing linear valve 92, and is supplied to the brake cylinders 18, 19, 26, and 27. High hydraulic pressure is avoided. The pressure reducing linear valve 92 is kept open while the pump device 12 is in the overpressurized state.

On the other hand, if the brake is being operated, the required brake fluid pressure PWC ^* is determined in S23 in the same manner as described above. In S24, it is determined whether or not the actual brake fluid pressure is higher than the required brake fluid pressure PWC ^* . Request if the brake fluid is higher than pressure PWC ^*, in S25, but pressure-reducing linear valve 92 is switched to the open state, if it is less than the required braking fluid pressure PWC ^*, at S26, pressure-reducing linear valve 92
Is closed. In this case, since the pressure-increasing linear valve 90 is in the open state, it is considered that the hydraulic pressure of the brake cylinder cannot be controlled by controlling the pressure-increasing linear valve 90. Therefore, the hydraulic pressure of the brake cylinder is controlled by controlling the pressure reducing linear valve 92.

As described above, in the present embodiment, when it is detected that the pump device 12 is in the over-pressurized state, the hydraulic pressure of the brake cylinders 18, 19, 26, 27 is excessively increased. That can be avoided. It is possible to prevent the brake fluid pressure from being increased against the driver's intention, and it is possible to reduce discomfort. Further, when it is detected that the brake fluid pressure has actually become higher than the set pressure, the pressure-reducing linear valve 92 is not opened, so that the over-pressurization condition (set pressure, set time, etc.) In some cases, the brake fluid pressure is actually the required brake fluid pressure (0
Before it becomes higher, that is, an excessive increase can be avoided. Further, it is possible to prevent an excessive load from being applied to the pump 30. In this case, the over-pressure suppression control controls the individual hydraulic pressure control valve device (the pressure reducing linear valve 92) for controlling the brake cylinder hydraulic pressure.
Therefore, there is no need to provide a dedicated relief valve for the pump 30, and the cost can be reduced accordingly. As described above, in the present embodiment, the portion storing and executing S1 to S5 of the brake fluid pressure control device 150, the portion measuring the continuous operation time of the pump motor 32, the accumulator pressure sensor 38, the temperature sensor 178 The over-pressurization detecting device is constituted by
6 is stored, executed, and the pressure-reducing linear valve 92 constitutes an excessive pressure-reducing device. The over-pressurization detecting device is also an over-pressurization detecting unit corresponding to the liquid temperature.

In the above-described embodiment, the over-pressurizing state is determined when the actual accumulator pressure is higher than the set pressure determined by the temperature of the working fluid. However, the set pressure is constant regardless of the temperature. It may be a value. In that case, the temperature sensor 178 becomes unnecessary. In particular, when the brake is being operated, the working fluid hardly flows out to the master cylinder 14 with the hydro booster regardless of whether the temperature is high or low, so that it is not necessary to consider the temperature. Further, the over-pressurizing condition can be different between during the brake operation and during the non-operation. For example, when the brake is being operated, the set pressure is set to a value determined based on a constant valve opening pressure of the pressure-increasing linear valve 90 regardless of the temperature. Further, when the continuous operation time of the pump 30 is longer than the set time, the output hydraulic pressure is higher than the set pressure, and the temperature is equal to or lower than a set temperature (for example, −20 °) at which the viscosity of the hydraulic fluid is a problem, The pressure reducing linear valve 92 may be switched to the open state. When the viscosity of the hydraulic fluid is low and the hydraulic fluid is quickly discharged to the master cylinder 14 with the hydro booster, the accumulator pressure may be high. Also in this case, the set pressure can be constant.
It is not essential that the over-pressurized state is detected based on both the accumulator pressure and the continuous energizing time, but may be detected based on either one. Good.

Further, an OFF command may be output to the drive circuit 180 for the pump motor 32 before or instead of opening the pressure reducing linear valve 92. For example, if it is determined that the pump 30 is overpressurized when the continuous operation time of the pump 30 is longer than the set time, the continuous operation time may be longer than the set time due to the abnormality of the accumulator pressure sensor 38. There is. That is, even if the actual accumulator pressure becomes higher than the upper limit of the set range, it may be detected as a value lower than the upper limit and the operation of the pump motor 32 may not be stopped. In this case, if an OFF command is output to the drive circuit 180, the operation of the pump motor 32 can be stopped. Although the operation of the pump motor 32 can be stopped even if an OFF command is output to the drive circuit 180, the rotation of the pump motor 32 can be stopped immediately if a reverse rotation command is output. Further, in the pump device 12, when the pump 30 is a gear pump and a check valve is not provided on the discharge side, a reverse rotation command of the pump motor 32 can be output to the drive circuit 180. The rotation of the pump motor 32 causes the pump 30 to rotate.
Is reversed, it is possible to prevent the output hydraulic pressure of the pump device 12 from becoming excessive. In this case, the hydraulic pressure detected by the accumulator pressure sensor 38 is
When the detected hydraulic pressure is lower than the set pressure by at least the set pressure, the accumulator pressure sensor 38 is determined to be abnormal and the drive circuit 1
It is also possible to output an OFF command or a reverse rotation command to 80. Also, the suction side of the pump 30 and the reservoir 36
And a switching valve can be switched from the open state to the closed state when the pump device 12 is in the over-pressurized state. If it is switched to the closed state, the pump 3
Since the hydraulic fluid is no longer supplied to 0, it is possible to suppress an excessive increase in the hydraulic pressure of the brake cylinder.

Further, when the pump device 12 is in an over-pressurized state, all the pressure-increasing linear valve devices 80 to 86
It is not essential to keep the pressure reducing linear valve 92 in the open state. The pressure reducing linear valves 92 of the linear valve devices 80 and 84 and the pressure reducing linear valves 92 of the linear valve devices 82 and 86 are alternately opened. You can also. If the pressure-reducing linear valve 92 is kept open, the continuous energization time is prolonged, and the pressure-reducing linear valve 92 may be overheated. can do. Further, the amount of heat generated in the pressure reducing linear valve 92 can be suppressed, and power consumption can be reduced.

In this embodiment, on each of the front wheel side and the rear wheel side, the pressure reducing linear valve 92 corresponding to the brake cylinder of the left wheel and the pressure reducing linear valve 92 corresponding to the brake cylinder of the right wheel alternately. It is opened. As described above, when the pump device 12 is abnormal (overpressurized state), the communication valves 58 and 60 are in the open state, and the two brake cylinders 18 and 19 are provided on the front wheel side and the rear wheel side, respectively. The brake cylinders 26 and 27 are in communication with each other. Therefore, if one of the pressure reducing linear valves 92 is opened without opening both of the pressure reducing linear valves 92 provided corresponding to the two brake cylinders 18 and 19, respectively, The hydraulic pressure of the two brake cylinders 18 and 19 can be controlled to the same height. Two brake cylinders 2
The same applies to 6, 27.

[0030] During non-braking operation, the elapsed time from the pump device 12 is detected to be in over-pressure _{condition, n (T L + T R} ) ~ {n (T L + T R) + T L}
During this period, the left decompression linear valve 92 on the front wheel side and the rear wheel side is opened, while the right decompression linear valve 92 is closed. Next, Δn (T _L + T
Between _{R) + T L} ~ (} n + 1) (T L + T R) , while the right side of the pressure-reducing linear valve 92 is opened, pressure-reducing linear valve 92 on the left side is closed. here,
n is an integer of 0 or more. The initial value is 0, and is increased by 1 each time the right pressure reducing linear valve 92 is changed from the open state to the closed state. During braking, if the actual brake fluid pressure is greater than the required brake fluid pressure,
The decompression linear valve 92 is opened.
When it is necessary to switch the pressure reducing linear valve 92 to the open state, the left pressure reducing linear valve 92 and the right pressure reducing linear valve 9 are respectively provided on the front wheel side and the rear wheel side.
2 are alternately switched to the open state.

In this embodiment, the brake fluid pressure control
The program is executed separately on the front wheel side and the rear wheel side.
When executed on the front wheel side, the brake fluid pressure
The average value of the two brake cylinders 18 and 19 on the front wheel side
Is performed on the rear wheel side.
The average value of the two brake cylinders 26 and 27 is used. What
It is essential to make the actual brake fluid pressure an average value
Instead of the hydraulic pressure of the two brake cylinders
Can be either one of
You. In this case, the hydraulic pressures of the two brake cylinders are the same.
Should be the same height. Here, the control for the front wheels is
A case in which this is performed will be described. 8 flowchart
In the over-pressure increase suppression control shown in FIG.
It is determined whether a key operation is being performed. In non-operation state
In step S32, the pump device 12
The elapsed time T from the detection of the state is 0 to T
_LIt is determined whether (n = 0). First S32
Is executed, the determination is YES, and the process returns to S33.
The linear valve device 80 corresponding to the left front wheel 16
The pressure reducing linear valve 92 is opened. Next, S3
4, the elapsed time T becomes T _L~ (T_L+ T_R)or not
Is determined, in this case, the determination is NO, and S
35, the pressure reducing linear valve of the linear valve device 82
The lube 92 is closed. Left side pressure reducing linear valve
92 is opened and the right depressurizing linear valve
92 is closed. Next, in S36
And the elapsed time T is (T_L+ T_R) Is determined
However, if S36 is executed first,
It becomes NO.

Steps S1-5 and 31-36 are repeatedly executed.
By this, the elapsed time T becomes the time T _LIf it exceeds, S3
2 is NO, and in S37, the left depressurizing
The linear valve 92 is switched to the closed state. in this case
Has elapsed time T_L~ (T_L+ T_R)
The determination in S34 is YES, and in S38, the right side
The pressure reducing linear valve 92 is switched to the open state. left
While the pressure-reducing linear valve 92 on the side is closed.
Side pressure reducing linear valve 92 is opened.
You. S1 to 5, 31, 32, 37, 34, 38 are repeated
The execution is performed so that the elapsed time T becomes the time (T_L+ T
_R), The determination in S34 is NO, and the process returns to S35.
Then, the right pressure reducing linear valve 92 is closed.
In other words, the determination in S36 becomes YES, and S3
At 9, the counter n is counted up. Less than
Below, the elapsed time T is (T_L+ T_R)-(2T_L+
T_R) Or not (2 · T_L+ T_R) To 2 (T_L+
T_R) Or 2 (T_L+ T_R) Or not
Are determined respectively, and the left and right pressure reducing linear valves
92 is opened and closed.

On the other hand, during the brake operation, the required brake fluid pressure PWC ^* is determined based on the operation state of the brake pedal 10 in S40, and the actual brake fluid pressure PWC (the left and right front wheels 16, 17 ⁾ is determined in S41.
Of the brake cylinders 18 and 19) is higher than the required brake fluid pressure PWC ^* . If not, in S42, the two pressure reducing linear valves 9
2 (the linear valve devices 80 and 82) are closed. In S43, it is determined whether one of the pressure-reducing linear valves 92 was previously open. If it was in the open state last time, the state of the flag is switched in S44. In this embodiment, when the flag is 0, the linear valve to be opened is the right pressure reducing linear valve 92, and when the flag is 1, the left pressure reducing linear valve 92 is used. You. The flag is a left / right decompression linear valve selection flag, and its initial value is 0.

If the actual brake fluid pressure PWC is higher than the required brake fluid pressure PWC ^* , it is determined in S45 whether or not the value of the flag is 1. If it is 1, S46
In, when the left pressure reducing linear valve 92 is opened while the right pressure reducing linear valve 92 is closed and the value of the flag is 0, in S47,
The left pressure reducing linear valve 92 is closed, while the right pressure reducing linear valve 92 is open. As described above, in the present embodiment, the left depressurizing linear valve 92 and the right depressurizing linear valve 92 are alternately opened. Therefore, heating of the pressure reducing linear valve can be suppressed. The same applies to the rear wheel side. In the present embodiment, the brake fluid pressure control device 15
The part that stores S6 of 0 (excessive pressure increase suppression control represented by the flowchart in FIG. 8), the part that executes S6, and the like constitute an alternate opening control unit.

In the above embodiment, the front wheel side,
Although the left decompression linear valve and the right decompression linear valve are opened in this order on each of the rear wheels, the invention is not limited to this. For example, on at least one of the front wheel side and the rear wheel side, the pressure reducing linear valve may be opened in the order of right and left. It is not essential that the left and right pressure reducing linear valves are alternately opened during the brake operation. Further, the structure of the brake device is not limited to that in the above embodiment. For example, instead of the master cylinder 14 with a hydro booster, a normal tandem type master cylinder not including a hydraulic booster can be used. In this case, the output hydraulic pressure of the pump device 12 is not supplied to the hydraulic booster, but is supplied only to the brake cylinder. Also, instead of the linear valve devices 80 to 86, the supply current is turned ON / OF.
An electromagnetic valve device including a pressure increasing / closing valve and a pressure reducing / opening / closing valve that is opened / closed by F may be used. Also in this case, when the pump device 12 is in the overpressurized state, the pressure reducing on-off valve is opened. Further, the pressure reducing linear valve 92 may be a normally open valve. With a normally open valve,
When the pump device 12 is abnormal, it is possible to avoid an increase in the hydraulic pressure of the brake cylinder without supplying current to the pressure reducing linear valve. Further, the pressure reducing linear valve on the rear wheel side may be a normally open valve, and the pressure reducing linear valve on the front wheel side may be a normally closed valve. In this case, only the front-wheel depressurization linear valve needs to be kept open, and the amount of heat generated by the depressurization linear valve in the overpressure suppression control can be suppressed. Further, a normally open valve can be provided in parallel with the pressure reducing linear valve 92. In addition, in addition to the modes described in [Problems to be Solved by the Invention, Problem Solving Means and Effects], it is possible to implement the present invention in various modifications and improvements based on the knowledge of those skilled in the art. it can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a brake device according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of a linear valve device included in the brake device.

FIG. 3 is a diagram showing a periphery of a hydraulic control device included in the brake device.

FIG. 4 is a flowchart showing a brake fluid pressure control program stored in a ROM of the fluid pressure control device.

FIG. 5 is a flowchart showing a part of the brake fluid pressure control program.

FIG. 6 is a flowchart showing a part of the brake fluid pressure control program.

FIG. 7 is a diagram showing a set pressure determination table stored in the ROM.

FIG. 8 is a flowchart showing a part of a brake fluid pressure control program stored in a ROM of a fluid pressure control device of a brake device according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 12 pump device 20, 21, 28, 29 brake 38 accumulator pressure sensor 50, 52 master shutoff valve 80-86 linear valve device 92 pressure reducing linear valve 54, 56 communication passage 58, 60 communication valve 150 brake fluid pressure control device 180 drive circuit

Claims (4)

[Claims] 1. A power type hydraulic pressure source which is operated by power and pressurizes and outputs hydraulic fluid, and is operated by supplying hydraulic fluid output from the power type hydraulic pressure source to a brake cylinder. A brake, an over-pressurization detecting device for detecting that the power type hydraulic pressure source is in an over-pressurized state, and the power type hydraulic pressure source is detected to be in an over-pressurized state by the over-pressure detecting device. A brake device that includes an overpressure suppression device that suppresses an overpressure of the hydraulic pressure of the brake cylinder. 2. The over-pressurization detecting device according to claim 1, wherein a continuous pressurizing operation time of said power type hydraulic pressure source exceeds a set time, and an output hydraulic pressure of said power type hydraulic pressure source exceeds a set pressure. When at least one of the above is satisfied, the power type hydraulic pressure source is in an over-pressurized state, and the brake device is provided between the brake cylinder and the low pressure source, and An overpressure suppression device that includes a release valve that can be switched between an outflow prevention state that prevents the flow of hydraulic fluid to the low pressure source and an outflow allowable state that allows the flow of hydraulic fluid from the brake cylinder to the low pressure source; The brake device according to claim 1, further comprising an opening valve control unit that switches the opening valve to the outflow allowable state. 3. The over-pressurization detecting device detects an overpressure when the output hydraulic pressure of the power hydraulic pressure source exceeds a set pressure determined based on a temperature of the hydraulic fluid. 3. The brake device according to claim 1, further comprising a liquid temperature corresponding over-pressurization detection unit that is in a pressurized state. 4. 4. The release valve is provided corresponding to each of two brake cylinders connected by a communication passage, and the over-pressure suppression device corresponds to one of the two brake cylinders. While the first opening valve is set to the outflow permission state, the second opening valve corresponding to the other brake cylinder is set to the outflow preventing state, a first depressurized state, and the first opening valve is set to the outflow preventing state. 4. The brake device according to claim 2, further comprising an alternate opening control unit configured to alternately display a second depressurized state in which the two-opening valve is set to an outflow permitting state. 5.