Electric brake device

Abstract

This electric brake device is provided with: a shut-off valve (21) for switching a connection path (12), which connects a reservoir tank (10) and a wheel cylinder (11), between a connected state and a shut-off state; an electric cylinder (23) connected to a main flow path (12A), which is a portion between the shut-off valve (21) and the wheel cylinder (11) in the connection path (12); and a control unit (33). The control unit (33) causes the brake fluid to be discharged to the main flow path (12A) by the electric cylinder (23) in a state where the main flow path (12A) is cut off by the shut-off valve (21), thereby generating brake fluid pressure within the wheel cylinder (11). In addition, after the brake fluid pressure generated in the wheel cylinder (11) due to the suction of the brake fluid from the main flow path (12A) by the electric cylinder (23) is reduced to atmospheric pressure, the control unit (33) maintains the cut-off state of the main flow path (12A) by the cut-off valve (21).

Description

TECHNICAL FIELD

[0001] The present application relates to an electric brake device. BACKGROUND

[0002] In Patent Literature 1, an electric brake device is described which transmits hydraulic pressure generated by an electric cylinder to a wheel cylinder to generate a brake fluid pressure in a wheel. In this electric brake device, a hydraulic pressure circuit between the electric cylinder and the wheel cylinder is connected to a reservoir via an electromagnetic cut valve.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2010-95023

[0004] In the electric brake device described above, it is considered to configure the hydraulic pressure circuit in such a manner that brake fluid discharged from the electric cylinder is returned to the reservoir in a state where the cut valve is open. In the electric brake device configured in this manner, it is necessary to close the cut valve before starting pressurization operation of the electric cylinder corresponding to a brake request. In order to keep the operation feeling constant, it is necessary to increase the operation speed of the cut valve at this time. The reason is as follows. If the operation speed of the cut valve is slow, brake fluid of a master cylinder flows into the wheel cylinder via the cut valve depending on operation of a brake pedal. As a result, the operation feeling changes. However, if the operation speed of the cut valve is increased, the operation sound of the cut valve increases, so it is likely to make the passenger feel uncomfortable. SUMMARY

[0005] An electric brake device which solves the above problem is provided with: a cut valve which is provided in a connection path connecting a reservoir and a wheel cylinder, switches the connection path to a communication state and a cut state; and an electric cylinder which is connected to a main flow path between the cut valve and the wheel cylinder, a piston in the cylinder performs linear motion according to driving of an electric motor, thereby enabling discharge of brake fluid to the main flow path and suction of the brake fluid from the main flow path, and in a state where the main flow path is cut by the cut valve, the brake fluid is discharged to the main flow path by the electric cylinder to generate a brake fluid pressure in the wheel cylinder, wherein a control section is provided which maintains the cut state of the cut valve with respect to the main flow path even after the brake fluid pressure generated in the wheel cylinder by suction of the brake fluid from the main flow path by the electric cylinder is reduced to atmospheric pressure.

[0006] While keeping the operation feeling constant, generation of the operation sound of the cut valve is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a diagram schematically showing the configuration of a first embodiment of an electric brake device.

[0008] Figure 2 is a flowchart of a brake control routine executed by a control section of the electric brake device described above.

[0009] Figure 3 is a graph showing the relationship between the peak value and the pullback amount.

[0010] Figure 4 is a graph schematically showing the state of the electric brake device in the generation of the braking force.

[0011] Figure 5 is a graph schematically showing the state of the electric brake device at the end of the braking.

[0012] Figure 6 is a graph schematically showing the state of the electric brake device in the pullback control.

[0013] Figure 7 is a graph schematically showing the state of the electric brake device at the generation of the kickback.

[0014] Figure 8 is a graph showing the relationship between the hydraulic pressure and the piston advance amount of the brake caliper.

[0015] Figure 9 is a flowchart showing a part of the brake control routine executed by the control unit in the second embodiment of the electric brake device.

[0016] Figure 10 is a timing chart showing one example of the control mode at the release of the braking in the electric brake device of the second embodiment, Figure 10 (a) of is a timing chart showing the progress of the brake hydraulic pressure, Figure 10 (b) of is a timing chart showing the progress of the screw stroke, Figure 10 (c) of is a timing chart showing the progress of the opening and closing state of the cut valve. DETAILED DESCRIPTION

[0017] (First Embodiment)

[0018] Hereinafter, the first embodiment in which the electric brake device is embodied will be described. The electric brake device of the present embodiment is configured as a device that generates a braking force at a wheel of a vehicle. Figures 1-8

[0019] <Configuration of the Electric Brake Device>

[0020] As shown in FIG. 1, the electric brake device 1 of the present embodiment is configured as a device that generates a braking force at a wheel of a vehicle. Figure 1 ​As shown, the electric brake device of the present embodiment has a reservoir tank 10 that stores brake fluid, and a wheel cylinder 11 that generates brake force at a wheel in accordance with supply of brake fluid pressure. In addition, the electric brake device has a fluid passage, i.e., a connection passage 12, that connects the reservoir tank 10 and the wheel cylinder 11. In the following description, the side closer to the wheel cylinder 11 along the connection passage 12 is described as the downstream side of the connection passage 12. In addition, the side closer to the reservoir tank 10 along the connection passage 12 is described as the upstream side of the connection passage 12.

[0021] The wheel cylinder 11 is provided inside a brake caliper 13 provided at a wheel of a vehicle. A brake caliper piston 14 is housed in the wheel cylinder 11 so as to be able to move linearly. A shield member 15 that elastically contacts the side surface of the brake caliper piston 14 is provided in the wheel cylinder 11. Two friction materials 16, 17 are provided in the brake caliper 13. The two friction materials 16, 17 are arranged so as to sandwich a rotating body, i.e., a brake disc 18, that rotates together with the wheel. The brake caliper piston 14 applies pressure to the friction material 16 toward the brake disc 18 in accordance with supply of brake fluid pressure to the wheel cylinder 11. Thereby, the brake disc 18 is sandwiched by the two friction materials 16, 17. A brake force is generated at the wheel by friction between the brake disc 18 and the friction materials 16, 17 at this time.

[0022] A master cylinder 20 that generates brake fluid pressure in accordance with depression of a brake pedal 19 is provided in the connection passage 12. The master cylinder 20 supplies discharge brake fluid in accordance with operation of the brake pedal 19 as an operation member. A normally open cut valve 21 is provided in a portion of the connection passage 12 that is downstream of the master cylinder 20. That is, the master cylinder 20 is provided in a portion of the connection passage 12 between the reservoir tank 10 and the cut valve 21. The connection passage 12 becomes a communication state that communicates the reservoir tank 10 and the wheel cylinder 11 at the time of opening of the cut valve 21. In addition, the connection passage 12 becomes a cut state that cuts the reservoir tank 10 and the wheel cylinder 11 at the time of closing of the cut valve 21. That is, the cut valve 21 is a valve that switches the connection passage 12 to the communication state and the cut state.

[0023] Furthermore, a stroke simulator 22 is connected to a portion of the connection passage 12 between the master cylinder 20 and the cut valve 21 via an electromagnetic drive type cut valve 22A. The stroke simulator 22 has a plunger that is supported by a spring built in. The cut valve 22A is closed at the time of opening of the cut valve 21. Therefore, at the time of opening of the cut valve 21, brake fluid pressure generated by depression of the brake pedal 19 is supplied to the wheel cylinder 11 from the master cylinder 20. At the time of closing of the cut valve 21, the master cylinder 20 and the wheel cylinder 11 are cut, and the cut valve 22A is opened. At this time, the stroke simulator 22 absorbs flow of brake fluid discharged from the master cylinder 20 by movement of the built-in plunger, while generating a reaction force against depression of the brake pedal 19.

[0024] In the following description, the portion of the connection passage 12 between the cut valve 21 and the wheel cylinder 11 will be described as a main flow passage 12A. The electric cylinder 23 is connected to the main flow passage 12A. The electric cylinder 23 generates brake hydraulic pressure by acting by power supply. A cylinder 24 housing a piston 25 so as to be linearly movable is provided in the electric cylinder 23. Further, a liquid chamber 26 into which brake fluid is introduced is formed by the piston 25 in the inside of the cylinder 24. The liquid chamber 26 is communicated with the connection passage 12. The volume of the liquid chamber 26 is changed by the linear movement of the piston 25 in the cylinder 24. In the following description, the direction in which the volume of the liquid chamber 26 is reduced in the linear movement direction of the piston 25 in the cylinder 24 will be described as a forward direction F, and the direction in which the volume of the liquid chamber 26 is increased will be described as a backward direction R.

[0025] The electric cylinder 23 is provided with an actuator 27 and a linear movement conversion mechanism 28. The actuator 27 receives power supply and generates rotational force. The actuator 27 is constituted by, for example, an electric motor and a reduction mechanism that reduces the rotation of the electric motor. The linear movement conversion mechanism 28 is provided with a rotational member 29 that receives the rotation of the actuator 27 and rotates. In addition, the linear movement conversion mechanism 28 is provided with a linear movement member 30 that linearly moves in the forward direction F and the backward direction R according to the rotation of the rotational member 29. Examples of the linear movement conversion mechanism 28 are a ball screw mechanism or a trapezoidal screw mechanism. The linear movement member 30 is brought into contact with the piston 25 by moving in the forward direction F. Further, the linear movement member 30 applies pressing to the piston 25 by further moving in the forward direction F in the state of being in contact with the piston 25. Thus, the piston 25 applies pressing to the brake fluid in the liquid chamber 26, and the electric cylinder 23 discharges brake fluid to the main flow passage 12A. The linear movement direction of the linear movement member 30 is switched according to the rotation direction of the actuator 27. In the following description, the rotational drive of the actuator 27 in the direction in which the linear movement member 30 moves in the forward direction F will be described as forward drive of the actuator 27. In addition, the rotational drive of the actuator 27 in the direction in which the linear movement member 30 moves in the backward direction R will be described as backward drive of the actuator 27.

[0026] In addition, a spring 31 and a stopper 32 are provided in the electric cylinder 23. The spring 31 is provided in the liquid chamber 26. Further, the spring 31 generates a compression reaction force against the pressing from the piston 25 in the forward direction F. The stopper 32 is brought into contact with the piston 25 at a predetermined position in the cylinder 24, and prohibits the movement of the piston 25 to the position in the backward direction R from the position. In the following description, the movement position of the piston 25 in contact with the stopper 32 will be described as an initial position.

[0027] As above, the electric cylinder 23 has the piston 25 that performs linear motion in the cylinder 24 according to driving of the electric motor in the actuator 27. Also, the electric cylinder 23 is capable of performing discharge of the brake fluid to the main flow path 12A and suction of the brake fluid from the main flow path 12A by linear motion of the piston 25 in the cylinder 24.

[0028] Also, the electric brake device of the present embodiment has the control section 33. The control section 33 is an electronic control unit for brake control. The stroke sensor 34 and the hydraulic pressure sensor 35 are connected to the control section 33. The stroke sensor 34 is a sensor that detects the depression amount of the brake pedal 19, i.e., the pedal stroke ST. The hydraulic pressure sensor 35 is a sensor that detects the pressure of the brake fluid in the main flow path 12A, i.e., the brake fluid pressure P. The brake fluid pressure P detected by the hydraulic pressure sensor 35 indicates the brake fluid pressure in the wheel cylinder 11. In addition, when the shut valve 21 is closed, the brake fluid pressure P detected by the hydraulic pressure sensor 35 indicates the brake fluid pressure generated by the electric cylinder 23.

[0029] The control section 33 opens and closes the shut valve 21 by turning on and off the electric current to the shut valve 21. When the shut valve 21 is opened, the cut valve 22A is closed, so the brake fluid pressure P generated in the master cylinder 20 according to the depression of the brake pedal 19 is supplied to the wheel cylinder 11. On the other hand, when the shut valve 21 is closed, the master cylinder 20 is disconnected from the wheel cylinder 11. The control section 33 performs driving control of the electric cylinder 23 based on the detection result of the pedal stroke ST by the stroke sensor 34 and the like in a state where the shut valve 21 is closed and the cut valve 22A is opened, thereby implementing brake control based on the by-wire system.

[0030] <By-wire system brake control>

[0031] Next, the details of the brake control based on the by-wire system will be described with reference to Figure 2 and Figure 3 In the present embodiment, the brake control based on the by-wire system is implemented by the control section 33. The brake control based on the by-wire system is implemented by the control section 33 in a state where the shut valve 21 is closed and the cut valve 22A is opened. In the brake control based on the by-wire system, the brake fluid pressure P generated in the master cylinder 20 according to the depression of the brake pedal 19 is supplied to the wheel cylinder 11, so the brake fluid pressure in the wheel cylinder 11 is controlled by the electric cylinder 23. Figure 2A flowchart showing a brake control routine executed by the control section 33 is shown in FIG. 6. Further, the control section 33 implements an initialization process before entering the brake control routine and when there is no driver operation. The initialization process is performed as described below. At the initialization process, the control section 33 drives the electric cylinder 23 with the cut valve 21 open to advance the piston 25 of the electric cylinder 23 from an initial position to a control initial position. Then, the control section 33 closes the cut valve 21 after the drive of the electric cylinder 23. The control initial position is a position after advancing the piston 25 from the initial position by a constant amount. In the case where such an initialization process is not implemented, there is a case where the hydraulic pressure is higher than the atmospheric pressure at the start of the brake control routine, i.e., the case where the hydraulic pressure is sealed. The initialization process is implemented in order to be able to lower the hydraulic pressure at the start of the brake control routine to the atmospheric pressure in such a case. Then, the control section 33 starts the present routine in accordance with the start of the brake control based on the by-wire system. By the implementation of the initialization process, at the start of the present brake control, the piston 25 of the electric cylinder 23 is positioned at the control initial position, and the cut valve 21 is in the closed state. Further, 0 is set as the initial value for the peak value and the last pullback amount to be described later.

[0032] The control section 33, if starting the brake control based on the by-wire system, first determines whether the pedal stroke ST is equal to or greater than a predetermined value Xl in step S100. The predetermined value Xl is set to a positive value smaller than the threshold value of the pedal stroke ST determined to have a brake request. In the case where the pedal stroke ST is smaller than the predetermined value Xl (NO), the control section 33, after a predetermined control period T elapses, again implements the determination of step S100.

[0033] In the case where the pedal stroke ST is equal to or greater than the predetermined value Xl (S100: YES), the control section 33 determines whether there is a brake request in step S110. The control section 33 determines that there is a brake request in the case where the pedal stroke ST is equal to or greater than a predetermined value X2 larger than the above-described predetermined value Xl.

[0034] The control section 33, in the case where it is determined that there is no brake request (NO), instructs the actuator 27 to advance drive corresponding to the last pullback amount in step S120. Then, the control section 33, after the above-described control period T elapses, again implements the determination of step S100. Further, the case where the process of step S120 is implemented, i.e., the case where the pedal stroke ST is equal to or greater than the predetermined value Xl and smaller than the predetermined value X2 means the case where the relatively light brake pedal 19 is depressed without reaching a brake force generation.

[0035] On the other hand, the control section 33, in a case where it is determined that there is a brake request (S110: YES), calculates a target hydraulic pressure in step S130 on the basis of the pedal stroke ST and the like. The target hydraulic pressure is a target value of the brake hydraulic pressure P to be generated by the electric cylinder 23. Further, the control section 33, in a case where the target hydraulic pressure is set, performs drive control of the actuator 27 of the electric cylinder 23 in a routine different from the present routine so as to cause the brake hydraulic pressure P detected by the hydraulic pressure sensor 35 to approach the target hydraulic pressure.

[0036] Next, the control section 33 determines whether or not the current brake hydraulic pressure P detected by the hydraulic pressure sensor 35 exceeds the peak value stored in step S140. Also, the control section 33, in a case where the current brake hydraulic pressure P exceeds the peak value (YES), replaces the value of the peak value with the current brake hydraulic pressure P in step S150, and thereafter causes the processing to proceed to step S160. On the other hand, the control section 33, in a case where the current brake hydraulic pressure P is equal to or less than the peak value (NO), skips step S150, and causes the processing to proceed to step S160. The peak value indicates the maximum value of the brake hydraulic pressure P in the wheel cylinder 11 that is raised by the electric cylinder 23 in the generation of the brake force this time.

[0037] If the processing proceeds to step S160, the control section 33 determines whether or not the brake request is released after the elapse of the control period T described above. Specifically, the control section 33 determines whether or not the pedal stroke ST is less than a predetermined value X2. In a case where the brake request is not released (NO), the control section 33 executes the processing of steps S130 to S160 described above again.

[0038] On the other hand, in a case where the brake request is released (YES), the control section 33 sets the atmospheric pressure as the value of the target hydraulic pressure in step S170. Then, if the brake hydraulic pressure P decreases to be equal to or less than the atmospheric pressure (S180: YES), the control section 33 causes the processing to proceed to step S190.

[0039] The control section 33 calculates a pullback amount on the basis of the peak value in step S190. Then, the control section 33 instructs a retreat drive of the actuator 27 corresponding to the pullback amount in the next step S200. The control section 33 instructs such a retreat drive of the actuator 27 on the condition that the state in which the pedal stroke ST is 0 continues for a predetermined time or more. In addition, the control section 33 fixes the speed of the retreat drive of the actuator 27 at this time to a predetermined speed.

[0040] Thereafter, the control section 33 resets the value of the peak value to 0 in step S210, and stores the pullback amount calculated in step S190 as the value of the last pullback amount. Then, the control section 33 causes the processing to return to step S100 after the elapse of the control period T described above.

[0041] In Figure 3The diagram shows the relationship between the pullback amount calculated by the control unit 33 in step S190 and the peak value used in the calculation. The larger the peak value, the larger the value that the control unit 33 will calculate as the pullback amount.

[0042] Furthermore, there are cases where the actuator 27, based on the forward drive command in step S120 and the reverse drive command in step S200, requires multiple control cycles T to drive. Also, there are cases where a braking request is generated before the drive of the actuator 27 based on these commands is completed. In such cases, the control unit 33 cancels these commands. Moreover, the control unit 33 controls the electric braking device to generate the braking force corresponding to the request by implementing the processing in step S110 where a braking request was determined.

[0043] <Effects of the First Embodiment>

[0044] The function and effects of this implementation method are explained.

[0045] In the brake control based on the drive-by-wire method, the control unit 33 maintains energization on the shut-off valve 21. Therefore, the main flow path 12A in the brake control is cut off from the reservoir 10.

[0046] exist Figure 4 The state of the electric braking device during braking is shown. If the brake pedal 19 is depressed and the pedal travel ST is greater than a predetermined value X2, the control unit 33 commands the actuator 27 of the electric cylinder 23 to drive forward. As a result, the piston 25 presses the brake fluid in the fluid chamber 26, thereby generating brake hydraulic pressure P in the electric cylinder 23. The brake hydraulic pressure P generated by the electric cylinder 23 is transmitted to the wheel cylinder 11. Through the transmitted brake hydraulic pressure P, the brake caliper piston 14 presses the friction material 16. As a result, the brake disc 18 is held by the two friction materials 16 and 17. The friction generated between the brake disc 18 and the friction materials 16 and 17 at this time generates braking force at the wheel.

[0047] exist Figure 5 The status of the electric braking device is displayed when braking ends. If the pedal travel ST is less than the predetermined value X1, the control unit 33 determines that the braking requirement has been released. Furthermore, the control unit 33 commands the actuator 27 of the electric cylinder 23 to reverse until the brake hydraulic pressure P detected by the hydraulic sensor 35 drops to atmospheric pressure.

[0048] After that, if the pedal stroke ST is 0 for a predetermined time or more, the control portion 33 instructs driving of the actuator 27 further in the retraction direction R from the position at the time of the end of braking. In the following description, the control of performing retraction driving of the actuator 27 after the end of braking is described as pullback control. The control portion 33 performs the pullback control in a state where the brake hydraulic pressure P generated in the wheel cylinder 11 is reduced to the atmospheric pressure and the cut valve 21 maintains the state of cutting off the main flow path 12A. Also, the control portion 33 drives the electric cylinder 23 in the direction of sucking brake fluid from the main flow path 12A in the pullback control.

[0049] In the electric brake device of the present embodiment, the actuator 27 of the electric cylinder 23 is driven after the end of braking due to the pullback control. If the electric brake device generates an operation sound after the end of braking due to the pullback control, there is a concern that the passenger feels uncomfortable. In contrast, the control portion 33 of the electric brake device of the present embodiment fixes the speed of driving of the actuator 27 in the retraction direction R in the pullback control to a predetermined speed. The fixed speed is set to a speed below the upper limit speed of the actuator 27 at which the operation sound is maintained to a size that does not cause the passenger to feel uncomfortable. Therefore, it is possible to suppress the operation sound of the actuator 27 in the pullback control after the end of braking to a size that does not give the passenger a sense of discomfort.

[0050] Figure 6 The state of the electric brake device in the pullback control is shown. If the pullback control is performed, the linear motion member 30 of the linear motion conversion mechanism 28 of the electric cylinder 23 moves to a position in the retraction direction R from the position at the time of the end of braking. Due to this, the piston 25 of the electric cylinder 23 becomes in a state of allowing movement to a position in the retraction direction R from the position at the time of the end of braking. The hydraulic circuit between the electric cylinder 23 and the wheel cylinder 11 at this time is blocked by the closing of the cut valve 21. Therefore, the brake caliper piston 14 of the wheel cylinder 11 becomes in a state of moving in conjunction with the piston 25 of the electric cylinder 23. Due to this, by the above-described pullback control, the brake caliper piston 14 becomes in a state of allowing movement to a position in the direction of moving away from the friction material 16 from the position at the time of the end of braking.

[0051] The control portion 33 stops driving of the electric cylinder 23 until braking is required again if the pullback control is ended. The control portion 33 thus stands by the electric cylinder 23 in a state where the piston 25 is in an operation position where the brake hydraulic pressure P is not generated at the time of non-braking.

[0052] In the running of the vehicle, there is a case where the brake caliper piston 14 is pushed back by the brake disc 18 due to vibration or displacement of the brake disc 18. This phenomenon is called back thrust. The back thrust is sometimes generated at the time of sharp turning or at the time of running on a bad road. In the case where the pull-back control is not performed, when the brake caliper piston 14 is pushed back due to the back thrust, the piston 25 of the electric cylinder 23 cannot retreat. Therefore, in the back thrust, drag caused by the pressing of the brake disc 18 against the friction material 16 is generated.

[0053] On the other hand, if the cut valve 21 is opened after the end of the braking, the brake fluid pushed out due to the retreat of the brake caliper piston 14 is released to the reservoir 10, so the generation of the drag at the time of the back thrust can be suppressed. However, in this case, the total amount of the brake fluid existing inside the main flow path 12A, the electric cylinder 23, and the wheel cylinder 11 is reduced by an amount corresponding to the brake fluid returned to the reservoir 10. Therefore, the responsiveness at the time of the next braking is reduced.

[0054] In Figure 7 The state of the electric brake device of the present embodiment at the time when the back thrust is generated is shown. As described above, in the electric brake device of the present embodiment, by performing the pull-back control after the end of the braking, the state where the movement of the piston 25 of the electric cylinder 23 to the retreat direction R is allowed is made. Therefore, by moving the piston 25 to the retreat direction R to make the electric cylinder 23 absorb the brake fluid pushed out from the wheel cylinder 11 due to the back thrust, the generation of the drag can be suppressed. At this time, the total amount of the brake fluid existing inside the main flow path 12A, the electric cylinder 23, and the wheel cylinder 11 is not changed, so the reduction of the responsiveness at the time of the next braking can also be suppressed.

[0055] Further, in the case where the pull-back control is performed, the operation position of the actuator 27 becomes the position of the retreat direction R compared to the case where the control is not performed. Therefore, if the state where the pull-back control is performed is maintained until the start of the next braking, the amount of the advance drive of the actuator 27 required for the start of the braking increases. Also, the responsiveness at the time of the braking decreases in correspondence thereto. In contrast to this, in the electric brake device of the present embodiment, the control section 33 instructs the advance drive of the actuator 27 by an amount equal to the pull-back amount in the previous pull-back control at the time when the pedal stroke ST becomes the predetermined value X1 (< X2) or more. Thereby, the operation position of the actuator 27 at the time of the start of the braking becomes the position of the advance direction F compared to the time when the pull-back control ends. Therefore, the reduction of the responsiveness at the time of the braking accompanying the pull-back control can be suppressed.

[0056] As above, the control portion 33 also maintains the cut-off state of the cut-off valve 21 to the main flow path 12A after the brake hydraulic pressure P generated in the wheel cylinder 11 by the suction of the brake fluid from the main flow path 12A by the electric cylinder 23 is reduced to the atmospheric pressure. In the electric brake device of this embodiment, the cut-off valve 21 does not need to be operated every time braking is performed, so the frequency of the operation sound of the cut-off valve 21 is reduced. Therefore, the electric brake device of this embodiment has an effect of suppressing the generation of the operation sound of the cut-off valve 21 that can cause the passenger to feel uncomfortable.

[0057] (Retraction amount of the retraction control of the actuator 27)

[0058] Figure 8 The passage of the brake hydraulic pressure P during the period from the start of braking to the end of braking and the passage of the advance amount of the caliper piston 14 are shown in the case where the peak value of the brake hydraulic pressure P in braking is PI and in the case where the peak value is P2 that is larger than PI. As shown in FIG. 6, even if the brake hydraulic pressure P of the wheel cylinder 11 is reduced to the atmospheric pressure at the end of braking, the caliper piston 14 does not completely return to the position at the start of braking. The position of the caliper piston 14 at the end of braking becomes a position further to the front side than at the start of braking. Figure 8

[0059] In the following description, the difference between the advance amount of the caliper piston 14 at the start of braking and at the end of braking is described as the hysteresis. The larger the peak value of the brake hydraulic pressure P in braking, the larger the hysteresis of the advance amount of the caliper piston 14. For example, in the case of FIG. 6, the hysteresis H2 at the peak value P2 is larger than the hysteresis HI at the peak value PI. Therefore, in the case where the retraction amount is constant, the position of the linear motion member 30 of the actuator 27 after the retraction control becomes a position further to the advance direction F in the case where the peak value is larger than in the case where the peak value is smaller. The more the position of the linear motion member 30 after the retraction control is to the advance direction F, the smaller the amount of retreat of the caliper piston 14 that can be permitted. Also, since the amount of retreat of the caliper piston 14 that can be permitted decreases, the drag suppression effect at the pushback time decreases. Figure 8

[0060] On the contrary, in the electric brake device of this embodiment, the control portion 33 stores the peak value of the brake hydraulic pressure P of the wheel cylinder 11 that rises by the electric cylinder 23 in the generation of the braking force. Also, the control portion 33 decides the retraction amount of the retraction control based on the peak value at the immediately preceding generation of the braking force. The retraction amount indicates the amount of drive of the actuator 27 to the retreat direction R in the retraction control. As shown in FIG. 7, the larger the peak value, the larger value the control portion 33 decides as the value of the retraction amount. Therefore, regardless of the peak value of the brake hydraulic pressure P at the immediately preceding braking, the drag suppression effect at the pushback time can be maintained. Figure 3

[0061] (Second Embodiment)​​​

[0062] Referring to Figure 9 and Figure 10 A second embodiment that embodies an electric brake device will be described. The electric brake device of the present embodiment is the same configuration as the electric brake device of the first embodiment shown in FIG. 1. In the present embodiment, the same reference numerals are added to the configurations common to the above-described embodiment and detailed description thereof is omitted. Figure 1

[0063] Further, "screw stroke SN" in the following description indicates the driving amount of the actuator 27. More specifically, the value of the screw stroke SN indicates the driving amount of the linear motion member 30 in the forward direction F from the position of the linear motion member 30 at the time when the piston 25 is driven to the control initial position in the initialization process.

[0064] Figure 9 A part of the process of the brake control routine executed by the control section 33 in the electric brake device of the present embodiment will be shown. The control section 33 of the electric brake device of the present embodiment starts the process of FIG. 9 in the case where the determination in step S180 of FIG. 8 is "Yes". Figure 2 Figure 9 Figure 9 The flowchart of FIG. 9 indicates the process started at the time when the brake hydraulic pressure P decreases to the atmospheric pressure after the cancellation of the brake request in the electric brake device of the present embodiment. Further, the control section 33 also in the process of FIG. 9, in the case where the brake request has been generated by the depression of the brake pedal 19, makes the process proceed to step S130 of FIG. 8 at that time. Figure 9 Figure 2

[0065] If the process of FIG. 9 is shifted to the process of FIG. 10, the control section 33 records the value of the current screw stroke SN as the value of the cancellation-time stroke SN0 in step S300. The cancellation-time stroke SN0 indicates the value of the screw stroke SN at the time when the brake hydraulic pressure P decreases to the atmospheric pressure after the cancellation of the brake request. Figure 9 Thereafter, the control section 33 makes the process proceed to step S330 in the case where either of the following conditions (A) and (B) is satisfied. The condition (A) means that the elapsed time after the cancellation of the brake request, i.e., the brake-cancellation-after time is the predetermined time TX or more (S310: Yes). The condition (B) means that the accelerator is on, i.e., the accelerator pedal is depressed (S320: Yes). The satisfaction of these conditions (A) and (B) indicates that after the cancellation of the brake request, the condition where the possibility that the brake pedal 19 is operated is lower than the predetermined threshold.

[0066]

[0067] ​​​​​​If the processing proceeds to step S330, the control section 33 determines whether or not to perform adjustment control. Specifically, the control section 33 determines in step S330 whether or not the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from a relationship set in advance. Also, the control section 33 determines in step S340 whether or not the relationship between the brake hydraulic pressure P and the position of the piston 25 has changed by a predetermined value or more before and after the operation of the motor cylinder 23. Further, the control section 33 makes the processing proceed to step S350 to perform adjustment control in a case where the above relationship deviates from the relationship set in advance (S330: YES), or in a case where the above relationship has changed by a predetermined value or more before and after the operation of the motor cylinder 23 (S340: YES).

[0068] The determination in step S330 will be described. In the present embodiment, a case where the release stroke SN0 is a predetermined value S1 or more and a predetermined value S2 or less is set as a case where the brake hydraulic pressure P and the position of the piston 25 are in a relationship set in advance. Thus, the control section 33 determines in step S330 that the above relationship deviates from the relationship set in advance in a case where the release stroke SN0 is less than the predetermined value S1, or in a case where it exceeds the predetermined value S2. The predetermined value S1 is set to a value of the screw stroke SN when the piston 25 is positioned in a position further in the advancing direction F than the initial position, and further in the retreating direction R than the control initial position. The predetermined value S2 is set to a value obtained by subtracting a necessary advancing amount from a maximum advancing position of the piston 25, and further subtracting a margin amount from the subtracted value. The maximum advancing position indicates a limit in the advancing direction F of a driving range of the piston 25 in the motor cylinder 23. The necessary advancing amount indicates a driving amount of the piston 25 in the advancing direction F required to raise the brake hydraulic pressure P from the atmospheric pressure to a required maximum pressure in braking.

[0069] Next, the determination in step S340 will be described. Figure 9 The "SNZ" described above indicates a value of the release stroke SN0 at the time of the last braking, that is, the last release stroke. The control section 33 obtains a variation width (= |SNZ - SN0|) of the value of the release stroke SN0 at the time of the last braking and the time of the present braking in step S340. Further, the control section 33 determines that the above relationship has changed by a predetermined value or more before and after the operation of the motor cylinder 23 in a case where the variation width is a predetermined value SX or more.

[0070] The control section 33 in a case where adjustment control is performed first opens the shut-off valve 21 in step S350. Next, the control section 33 instructs the actuator 27 to drive the piston 25 to the control initial position in step S360. Then, if the driving of the piston 25 to the control initial position is completed (S370: YES), the control section 33 closes the shut-off valve 21 (S380). In the present embodiment, the processing in steps S350 to S380 corresponds to processing for adjustment control.

[0071] If the adjustment control is completed, the control unit 33 proceeds to step S390. If no adjustment process is performed (S330: No, and S340: No), the control unit 33 skips steps S350 to S380 and proceeds to step S390. In step S390, the control unit 33 records the value of the release stroke SN0 during the current braking as the value of the previous release stroke SNZ. Then, the control unit 33 proceeds to... Figure 2 In step S190, pull-back control is executed.

[0072] <The function and effects of the second embodiment>

[0073] The function and effects of this implementation method are explained.

[0074] exist Figure 10 An example of an implementation of the adjustment control in the electric braking device of this embodiment is shown. Figure 10 (a) represents the displacement of the brake hydraulic pressure P. Figure 10 (b) represents the movement of the leadscrew stroke SN. Figure 10 (c) indicates the shift in the open / closed state of shut-off valve 21.

[0075] exist Figure 10 At time t1, the brake hydraulic pressure P decreases to atmospheric pressure. Figure 10 In this case, the lead screw travel SN at that moment, i.e., the release travel SN0, exceeds the predetermined value S2. In this situation, the control unit 33 determines that the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from a predetermined relationship. On the other hand, when the brake hydraulic pressure P decreases to atmospheric pressure at time t1, and a predetermined time TX has elapsed at time t2, the control unit 33 determines that the probability of the brake pedal 19 being operated is lower than a predetermined threshold. Then, the control unit 33 begins to adjust the control at time t2. Specifically, at time t2, the control unit 33 opens the shut-off valve 21 and instructs the actuator 27 to drive the piston 25 towards the control initial position. In this case, the piston 25 is driven in the backward direction R.

[0076] In this embodiment, the lead screw stroke SN is defined by setting the value of the piston 25 when it is in the initial control position to "0". Therefore, in Figure 10 At time t3, when the value of the lead screw stroke SN becomes 0, the piston 25 reaches the initial control position. The control unit 33 ends the adjustment control by closing the shut-off valve 21 at time t3. When the shut-off valve 21 is open, the main flow path 12A is connected to the reservoir 10. Therefore, the result of the adjustment control is to adjust the relationship between the brake hydraulic pressure P and the position of the piston 25 so that the brake hydraulic pressure P when the piston 25 is in the initial control position is atmospheric pressure.

[0077] The control section 33 starts the pullback control from the time t3 at which the adjustment control is finished. Specifically, the control section 33 instructs the actuator 27 to perform the drive in the backward direction R by the amount set in accordance with the peak value of the brake hydraulic pressure P in braking. In Figure 10 the case, the pullback control is completed at the subsequent time t4.

[0078] In Figure 10 , the case in which the release stroke SN0 exceeds the predetermined value S2 is explained. The control section 33 also determines that the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from the predetermined relationship and performs the adjustment control in the case in which the release stroke SN0 is smaller than the predetermined value S1. In the adjustment control, the drive of the piston 25 in the backward direction R is instructed at the time t2 in Figure 10 , and the piston 25 is moved to the control initial position. In contrast, in the case in which the release stroke SN0 is smaller than the predetermined value S1, the drive of the piston 25 in the forward direction F is instructed at the time t2, and the piston 25 is moved to the control initial position, which is different from Figure 10 . The actions other than this are the same as in Figure 10 .

[0079] As described above, the electric brake device of the present embodiment adjusts the amount of brake fluid in the electric cylinder 23, the main flow path 12A, and the wheel cylinder 11 so that the brake hydraulic pressure P when the piston 25 is positioned at the control initial position becomes the atmospheric pressure in the initialization processing. Moreover, the electric brake device raises the brake hydraulic pressure P supplied to the wheel cylinder 11 from the atmospheric pressure by driving the piston 25 in the forward direction F from the control initial position.

[0080] In such an electric brake device, after the implementation of the initialization processing, the relationship between the position of the piston 25 and the brake hydraulic pressure P is sometimes changed due to the wear of the friction materials 16, 17, the thermal expansion of the brake fluid, or the like. Moreover, as a result, it is possible that the brake hydraulic pressure P does not decrease to the atmospheric pressure even if the piston 25 is retracted to the initial position, or the brake hydraulic pressure P does not reach the required maximum pressure even if the piston 25 is advanced to the maximum advanced position.

[0081] In contrast, the control section 33 of the electric brake device of the present embodiment performs adjustment control of the relationship between the adjusted brake hydraulic pressure P and the position of the piston 25. The control section 33 starts the adjustment control in a state where the brake hydraulic pressure P generated in the wheel cylinder 11 is reduced to the atmospheric pressure and the main flow path 12A is cut off from the reservoir 10 by the cut valve 21. Further, the control section 33 performs the adjustment control to adjust the relationship between the brake hydraulic pressure P and the position of the piston 25 by driving the electric cylinder 23 during a period when the cut valve 21 is temporarily opened. Specifically, the control section 33 performs the adjustment control by driving the piston 25 to the control initial position in a state where the cut valve 21 is opened, and then closing the cut valve 21. After the implementation of such adjustment control, the brake fluid amount in the main flow path 12A, the electric cylinder 23, and the wheel cylinder 11 is adjusted so that the brake hydraulic pressure P when the piston 25 is positioned at the control initial position becomes the atmospheric pressure, as in the implementation of the initialization processing.

[0082] Further, the control section 33 performs the adjustment control when the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from a relationship set in advance. In addition, the control section 33 performs the adjustment control when the relationship between the brake hydraulic pressure P and the position of the piston 25 changes by a predetermined value or more before and after the operation of the electric cylinder 23. In such a case, the adjustment control is performed in a situation where the deviation of the relationship between the brake hydraulic pressure P and the position of the piston 25 is large and approaches a state where the brake force cannot be properly controlled. Therefore, it is possible to suppress the frequency of implementation of the adjustment control and reduce the power consumption accompanying the implementation of the control.

[0083] There is a case where the brake pedal 19 is operated during the execution of the adjustment control. If the brake pedal 19 is operated, the master cylinder 20 operates, and the brake fluid amount of the main flow path 12A changes. Therefore, if the brake pedal 19 is operated during the execution of the adjustment control, the accuracy of the adjustment of the relationship between the brake hydraulic pressure P and the position of the piston 25 based on the control decreases. In contrast, the control section 33 of the electric brake device of the present embodiment performs the adjustment control in a case where the possibility that the brake pedal 19 is operated is lower than a predetermined threshold value. More specifically, the control section 33 determines that the possibility that the brake pedal 19 is operated is lower than the predetermined threshold value in a case where a predetermined time TX or more has elapsed after the cancellation of the brake request, or in a case where the accelerator pedal is depressed. Therefore, the accuracy of the adjustment of the relationship between the brake hydraulic pressure P and the position of the piston 25 based on the adjustment control improves.

[0084] (Stroke SN0 at the time of cancellation)

[0085] In Figure 9 In step S330 and step S340, the stroke SN0 at the time of cancellation is used to determine whether to perform the adjustment control. The stroke SN0 at the time of cancellation corresponds to the position of the piston 25 when the brake hydraulic pressure P is reduced to the atmospheric pressure after the cancellation of the brake request.

[0086] On the other hand, as described above, there is a hysteresis in the position of the brake caliper piston 14 before and after braking. The same applies to the position of the piston 25 of the electric cylinder 23 before and after braking. Moreover, the greater the peak value of the brake hydraulic pressure P during braking, the greater the hysteresis. By taking such hysteresis into account, it is possible to improve the accuracy of the determination in step S330 and step S340. Specifically, in step S300 of the above embodiment, the value of the release stroke SN0 is set in such a manner that the above-described determination accuracy is improved. In step S300, the control section 33 calculates the hysteresis in the position of the piston 25 of the electric cylinder 23 before and after braking, based on the peak value of the brake hydraulic pressure P during braking. Moreover, the control section 33 sets, as the value of the release stroke SN0, a value obtained by subtracting the hysteresis from the current value of the screw stroke SN. Figure 9

[0087] (Influence of viscosity of brake fluid)

[0088] In the adjustment control, the relationship between the brake hydraulic pressure P and the position of the piston 25 is adjusted by driving the piston 25 in a state in which the cut valve 21 is opened to allow supply and discharge of the brake fluid between the main flow passage 12A and the reservoir 10. In the case where supply and discharge of the brake fluid between the main flow passage 12A and the reservoir 10 via the cut valve 21 in the adjustment control proceeds smoothly, the brake hydraulic pressure P is maintained substantially at atmospheric pressure from the start to the end of the adjustment control. However, in the case where the viscosity of the brake fluid is high, supply and discharge of the brake fluid between the main flow passage 12A and the reservoir 10 via the cut valve 21 in the adjustment control cannot proceed smoothly. Therefore, there is a case where the brake hydraulic pressure P deviates from atmospheric pressure at the time when the piston 25 reaches the control initial position. If the cut valve 21 is closed to end the adjustment control in a state where the brake hydraulic pressure P deviates from atmospheric pressure, the above-described relationship cannot be adjusted properly. Therefore, in the case where the viscosity of the brake fluid is higher than a certain level, it is preferable that the open valve of the cut valve 21 be maintained after the driving of the piston 25 to the control initial position is completed. Moreover, it is preferable that the higher the viscosity of the brake fluid, the longer the time for which the open valve of the cut valve 21 is maintained.

[0089] (Other Embodiments)

[0090] The above-described embodiments can be modified as follows. The above-described embodiments and the following modified examples can be implemented in combination with each other within a range in which there is no technical contradiction.

[0091] ・In the second embodiment, in the case where a predetermined time TX or more elapses after the release of the brake request, or in the case where the accelerator pedal is depressed, it is determined that the possibility that the brake pedal 19 is operated is lower than a predetermined threshold. Such determination can be appropriately modified. In addition, it can be that the adjustment control is performed regardless of the level of the possibility that the brake pedal 19 is operated.​

[0092] • As long as the brake hydraulic pressure P is reduced to atmospheric pressure and the main flow path 12A is kept in the off state by the shut-off valve 21, the adjustment control and pull-back control can be executed sequentially, and the execution of the adjustment control can start from any timing.

[0093] ·exist Figure 9 In step S330, if the stroke SN0 is less than the predetermined value S1 or exceeds the predetermined value S2 during release, it is determined that the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from the preset relationship. Additionally, Figure 9 In step S340, it is determined whether the change in the value of the release stroke SN0 between the previous braking and the current braking (=|SNZ-SN0|) is greater than or equal to a predetermined value SX. Furthermore, it is determined whether the relationship between the brake hydraulic pressure P and the position of the piston 25 has changed by a predetermined value or greater before and after the operation of the electric cylinder 23. These determinations can also be performed in ways other than those described above.

[0094] • In the second embodiment, adjustment control is performed when the relationship between the brake hydraulic pressure P and the position of the piston 25 deviates from a predetermined relationship, or when the relationship changes by more than a predetermined value before or after the operation of the electric cylinder 23. Adjustment control may be performed only in any of these cases. Alternatively, adjustment control may be performed regardless of any of these cases.

[0095] • The electric braking device in the second embodiment can also be configured not to perform pull-back control.

[0096] • In the above embodiment, the reversing drive of the actuator 27 of the electric cylinder 23 stops when the brake hydraulic pressure P drops to atmospheric pressure after the brake requirement has been released. The stopping time of the reversing drive can also be determined based on parameters other than the brake hydraulic pressure P. Examples of parameters other than the brake hydraulic pressure P include the forward movement of the piston 25 of the electric cylinder 23. For example, the control unit 33 can reverse the actuator 27 when the brake requirement is released until the forward movement of the piston 25 from the position at the start of braking is zero. The forward movement of the piston 25 can be calculated by providing a position sensor in the electric cylinder 23 to measure the position of the piston 25 within the cylinder 24, or by calculating based on the driving amount of the actuator 27 after the start of braking.

[0097] • In the above embodiment, before braking begins, the control unit 33 commands the actuator 27, which corresponds to the pull-back amount in the previous pull-back control, to drive forward. However, this command may not be executed.

[0098] ・In the above-described embodiment, the amount of pullback in the pullback control is determined based on the peak value of the brake hydraulic pressure P of the wheel cylinder 11 that rises by the electric cylinder 23 at the immediately preceding brake force generation. The amount of pullback can also be determined based on a parameter other than the peak value, or made a fixed value. As the parameter other than the peak value of the brake hydraulic pressure P of the wheel cylinder 11, the amount of advance of the wheel cylinder 11 can be cited. The amount of advance of the wheel cylinder 11 is found by providing a position sensor that measures the position of the brake caliper piston 14 to the wheel cylinder 11, or by providing a flowmeter to the main flow path 12A and estimating from the measured value of the flow rate.

[0099] ・In the above-described embodiment, the amount of pullback in the pullback control is determined based on the peak value of the brake hydraulic pressure P of the wheel cylinder 11 that rises by the electric cylinder 23 at the immediately preceding brake force generation. The amount of pullback can also be determined based on a parameter other than the peak value, or made a fixed value. As the parameter other than the peak value of the brake hydraulic pressure P of the wheel cylinder 11, the amount of advance of the wheel cylinder 11 can be cited. The amount of advance of the wheel cylinder 11 is found by providing a position sensor that measures the position of the brake caliper piston 14 to the wheel cylinder 11, or by providing a flowmeter to the main flow path 12A and estimating from the measured value of the flow rate. Figure 2

[0100] ・In the above-described embodiment, the drive speed of the actuator 27 in the backward direction R in the pullback control is fixed, but can also be made variable. In this case, it is also preferable to limit the drive speed to a constant speed or less to keep the operation sound of the actuator 27 to a size that does not make the passenger feel uncomfortable.

[0101] ・The cut valve 21 can also be temporarily opened after the brake ends before the pullback control is started. Even in this case, as long as the electric cylinder 23 is put on standby in a state where the cut valve 21 is closed, and the closing of the cut valve 21 is maintained until the brake ends, the responsiveness at the start of the brake can be ensured.

[0102] ・The pullback control can also not be implemented after the brake ends.

[0103] ・The control section 33 can be configured as one or more dedicated hardware circuits or a circuit including a combination thereof, such as one or more processors that act in accordance with a computer program, or perform at least a part of the processing in various processes. As the dedicated hardware, an application specific integrated circuit (ASIC) for a specific purpose can be cited, for example. The processor includes a CPU, and a memory such as a RAM and a ROM, and the memory stores program codes or instructions that cause the CPU to execute the processes. The memory, that is, the storage medium, includes all usable media that can be accessed by a general-purpose or dedicated computer.

[0104] (Additional Notes)

[0105] ​[Para 1] The electric brake device according to the second or third aspect, wherein the control unit increases the driving amount of the electric cylinder in the direction of drawing the brake fluid from the main flow path in the pullback control when the peak value of the brake fluid pressure at the immediately preceding braking is large, compared to when the peak value is small.

[0106] [Para 2] The electric brake device according to any one of the second to fourth aspects and Para 1, wherein the electric cylinder includes a linear motion conversion mechanism that converts rotation of a rotating member of the actuator into linear motion of a linear motion member, a piston that linearly moves within a cylinder according to the linear motion of the linear motion member, and a fluid chamber that is divided by the cylinder and the piston and configured to apply a pressing force to brake fluid introduced into the fluid chamber to generate a fluid pressure according to the linear motion of the piston.

Claims

1. An electric braking device comprising: a shut-off valve disposed in a connection path connecting a fluid reservoir to a wheel cylinder, for switching the connection path between an open state and a shut-off state; and an electric cylinder connected to the portion of the connection path between the shut-off valve and the wheel cylinder, i.e., the main flow path, wherein a piston within the cylinder moves linearly under the drive of an electric motor, thereby enabling the discharge of brake fluid into the main flow path and the suction of brake fluid from the main flow path, wherein, when the main flow path is shut off by the shut-off valve, the electric cylinder discharges brake fluid into the main flow path, thereby generating brake pressure in the wheel cylinder, wherein... The device includes a control unit that maintains the shut-off valve's shut-off state on the main flow path even after the brake fluid pressure generated in the wheel cylinder due to the suction of brake fluid from the main flow path by the electric cylinder has decreased to atmospheric pressure.

2. The electric braking device according to claim 1, wherein, When the brake fluid pressure generated in the wheel cylinder is reduced to atmospheric pressure and the shut-off valve is kept in the state of cutting off the main flow path, the control unit performs pull-back control, which drives the electric cylinder in the direction of drawing brake fluid from the main flow path.

3. The electric braking device according to claim 2, wherein, In the aforementioned pull-back control, the control unit changes the driving amount of the electric cylinder based on the brake fluid pressure in the wheel cylinder that rises through the electric cylinder. The driving amount of the electric cylinder is a driving amount in the direction of drawing brake fluid from the main flow path.

4. The electric braking device according to claim 1, wherein, From the state where the brake hydraulic pressure generated in the wheel cylinder decreases to atmospheric pressure and the main flow path is cut off by the cut-off valve, the control unit adjusts the relationship between the brake hydraulic pressure and the position of the piston by temporarily opening the cut-off valve and driving the electric cylinder.

5. The electric braking device according to claim 4, wherein, The control unit performs the aforementioned adjustment control when the relationship between the brake hydraulic pressure and the position of the piston deviates from a preset relationship.

6. The electric braking device according to claim 4, wherein, The aforementioned control unit performs the aforementioned adjustment control when the relationship between the aforementioned brake hydraulic pressure and the aforementioned piston position changes by more than a predetermined value before and after the operation of the aforementioned electric cylinder.

7. The electric braking device according to any one of claims 4 to 6, wherein, The portion of the aforementioned connection circuit between the fluid reservoir and the aforementioned shut-off valve also includes a master cylinder, which supplies and discharges brake fluid according to the operation of the operating components. The control unit performs the adjustment control when the probability of the operating component being operated is lower than a predetermined threshold.

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