JPH0210751B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic brake drive, and more particularly to a hydraulic brake drive with an anti-skid mechanism.

Conventionally, the hydraulic pressure booster main body has a hydraulic pressure booster main body and a hydraulic pressure controller main body, and the hydraulic pressure booster main body has a first hydraulic fluid passage that guides the hydraulic fluid discharged from the pump to the suction side of the pump. An input rod that throttles the middle of the first oil passage in conjunction with the brake pedal, and an output rod that is driven by the differential pressure generated between the upstream and downstream sides of the throttle section and acts on the piston in the master cylinder. and a second oil passage for guiding brake fluid discharged from the discharge port of the master cylinder to the wheel brakes, and a small diameter cylinder chamber located in the middle of the second oil passage. , a large-diameter cylinder chamber following the small-diameter cylinder chamber, and a check valve provided on the upstream side of the small-diameter cylinder chamber in the middle of the second oil passage, one end of which fits into the large-diameter cylinder chamber and the other end of which fits into the small-diameter cylinder chamber. A piston of different diameter that fits and has a protrusion on the other end that abuts the check valve, a third oil passage connected to the large-diameter cylinder chamber, and a signal from a lock detection section that detects whether the wheels are locked. A hydraulic brake drive device is used which is provided with a hydraulic fluid supply passage and a hydraulic fluid return passage, each of which is connected to the third hydraulic fluid passage via a switching valve that is switched by.

By the way, in this type of conventional hydraulic brake drive device, the hydraulic fluid supply passage and the hydraulic fluid return passage within the hydraulic control unit main body are separate from the pump for hydraulic pressure boosting, and the discharge side and suction side of the pump are separate from each other. The following problems arose due to the connection between the two sides via piping.

Since the two pumps are installed separately on the vehicle body, a large installation space is required.

The hydraulic pressure of the hydraulic fluid supplied from the hydraulic fluid supply passage to the large-diameter cylinder chamber is controlled by the first pump in the hydraulic pressure booster body.
Since the hydraulic pressure remains constant regardless of the increase in hydraulic pressure upstream of the throttle part of the oil passage, as the pedal depression force increases, the pushing force on the opening side of the check valve by the piston of different diameter weakens, resulting in stable brake operation. Undesirable in terms of sex.

The present invention aims to solve the above-mentioned problem, and the present invention connects the hydraulic fluid supply passage in the hydraulic pressure control section to the middle of the first hydraulic fluid passage on the upstream side of the control section in the main body of the hydraulic pressure booster. It is characterized by this. In addition, when the pressure in the hydraulic fluid supply passage becomes below a certain level, the third hydraulic fluid passage that connects the large-diameter cylinder chamber and the hydraulic fluid supply passage in the main body of the hydraulic pressure control unit is installed. It is characterized by being provided with a valve device that closes the valve midway.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is the main body of the hydraulic pressure booster, and 2 is the main body of the hydraulic pressure control unit. Here, both 1 and 2 are integrally formed.

A cylinder chamber 3 is formed in the main body 1 of the hydraulic pressure booster, and an isop rod 5 and an output rod 6 connected to a brake pedal 4 are inserted into the cylinder chamber 3 so as to be movable in the axial direction. Reference numerals 7 and 8 designate pipe connection ports opening into the cylinder chamber 3, and both pipe connection ports 7 and 8 are connected to the discharge side and suction side of the pump 11 via pipes 9 and 10. A variable throttle section 12, which is a control section, is formed between the input rod 5 and the output rod 6.
A passage 13 is formed that guides the hydraulic fluid contained therein to the constriction part 12. The cylinder chamber 3, the passage 13, the throttle part 12, etc. each constitute a part of the first oil passage A. The throttle part 12 is connected to the spring 1 when the brake is not applied.
4, but when the input rod 5 is moved to the left in the figure by interlocking the brake pedal 4, the throttle section 12 is narrowed and the upstream side _A1 is opened.
A differential pressure is generated between the master cylinder 1 and the downstream side _A2 , and the pressure difference causes the push rod 6 to move leftward, thereby causing a piston (not shown) in the master cylinder 15 to move leftward. This piston pressurizes the brake fluid in the master cylinder 15 by moving to the left, and causes the brake fluid to be discharged from the discharge port 16. Since the internal configuration of the hydraulic pressure booster main body 1 and the internal configuration of the master cylinder 15 are already well known, the above description will be limited here.

A second oil passage B is formed in the hydraulic control unit main body 2 for guiding the brake fluid discharged from the discharge port 16 of the master cylinder 15 to the wheel brakes 17 such as disc brakes or drum brakes. The inlet of this second oil passage B;
The outflow ports are connected to the discharge port 16 and the wheel brakes 17 via pipes 18 and 19, respectively.

A small-diameter cylinder chamber 20 that opens midway through the second oil passage B is formed in the hydraulic control section main body 2, and a large-diameter cylinder chamber 21 that continues from the small-diameter cylinder chamber 20 is further formed. Further, a check valve 22 is provided in the middle of the second oil passage B on the upstream side of the small diameter cylinder chamber 20, and this check valve 22 is biased by a spring 23 in a closing direction toward the downstream side.

24 is a different diameter piston, which has a small diameter portion 24A that is slidably fitted into the small diameter cylinder chamber 20 and a large diameter portion 24B that is slidably fitted into the large diameter cylinder chamber 21.
A protrusion 24C that can come into contact with the check valve 22 is formed at the tip of the small diameter portion 24A. 25 and 26 are seal rings.

A third oil passage C is connected to the large diameter cylinder chamber 21, and a switching valve 27 is connected to the third oil passage C.
The hydraulic fluid supply passage 28 and the hydraulic fluid return passage 2
9 is connected. The switching valve 27 is biased by a spring 30 in the direction of opening the hydraulic fluid supply passage 28 and closing the hydraulic fluid return passage 29. The hydraulic control unit body 2 is provided with a coil 31 surrounding the switching valve 27.
1 is designed to be excited by the control circuit 34 when a detection signal from the lock detection section 33 that detects the locked state of the wheel 32 is sent to the control circuit 34, and the coil 31 is excited by the control circuit 34. Therefore, the switching valve 27 is switched to close the hydraulic fluid supply passage 28 and open the hydraulic fluid return passage 29 at the same time.

The working fluid return passage 29 is connected via a pipe 35 to the middle of the pipe 10 on the suction side of the pump 11 . On the other hand, the hydraulic fluid supply passage 28 is connected to A ₁ on the upstream side of the throttle part 12 in the first oil passage A in the hydraulic pressure booster main body 1 . Here, since the hydraulic fluid supply passage 28 is formed by drilling or the like in the two bodies 1 and 2 that are integrated with each other, a piping structure is not required, and the number of parts, assembly, and man-hours can be reduced. is planned.

Next, the operation of the above embodiment will be explained.

First, the case where the wheels 32 are not locked will be explained. In this state, the coil 31 is demagnetized and the anti-skid mechanism is inactive. Therefore, the switching valve 27 closes the hydraulic fluid return passage 29 and opens the hydraulic fluid supply passage 28, so that the passage 28 and the large diameter cylinder chamber 21 communicate with each other.

In this anti-skid non-operating state, when the brakes are not applied, the hydraulic fluid is pushed upstream of the throttle part 12 due to resistance when it passes through the throttle part 12 in the cylinder chamber 3, piping resistance when returning to the pump 11, etc.
A ₁ 's hydraulic pressure has increased slightly. This hydraulic pressure is applied to the large diameter portion 24 of the different diameter piston 24 in the large diameter cylinder chamber 21 from the hydraulic fluid supply passage 28 through the third oil passage C.
It acts on the end face of B and pushes the different diameter piston 24 to the left. For this reason, the check valve 22 has a spring 23
It is pushed open by the protrusion 24C against the force.
Therefore, the discharge port 16 of the master cylinder 15 and the wheel brake 17 are in communication via the second oil passage B.

When the brake pedal 4 is depressed in the anti-skid non-operating state, the input rod 5 moves to the left and the throttle portion 12 is throttled. For this reason,
The hydraulic pressure on the upstream side A1 of the throttle section ₁₂ becomes higher than the hydraulic pressure on the downstream side _A2 , and this differential pressure pushes the output rod 6 to the left, causing the master cylinder 1 to
Push the piston number 5 to the left and release the master cylinder 1.
Brake fluid is discharged from the discharge port 16 of 5. Since this brake fluid pressure acts on the small diameter portion 24A of the different diameter piston 24, a rightward force is applied to the different diameter piston 24, but the pressure receiving area at the right end of the different diameter piston 24 is larger than the left end. Moreover, since the leftward force acting on the large diameter portion 24B side of the different diameter piston 24 increases as the hydraulic pressure increases on the upstream side A2 of the throttle portion ₁₂ , the check valve 22
The oil passage B is kept open. Therefore, the brake fluid pressure is applied to the wheel brakes 17 via the second fluid passage B, and the wheels 32 are braked.

Next, when the brake fluid pressure from the master cylinder 15 becomes excessive and the wheels 32 are about to lock up, the lock detection section 33 detects this state,
The coil 31 is excited by the detection signal.
As a result, the switching valve 27 is switched to cut off the communication between the hydraulic fluid supply passage 28 and the third oil passage C, and at the same time open the hydraulic fluid return passage 29 to connect the hydraulic fluid supply passage 28 and the third oil passage C.
It communicates with the oil passage C. Therefore, the hydraulic fluid in the large-diameter cylinder chamber 21 is returned to the suction side of the pump 11 from the third hydraulic fluid passage C through the hydraulic fluid return passage 29 and the pipes 35 and 10. As a result, the leftward force acting on the different diameter piston 24 weakens, and the rightward force due to the brake fluid pressure increases, pushing the different diameter piston 24 to the right and closing the check valve 22. Furthermore, as the different diameter piston 24 moves to the right, the brake fluid storage capacity of the small diameter cylinder chamber 20 increases, so the brake fluid pressure acting on the wheel brakes 17 decreases by the increased volume, and the braking force decreases. It will be canceled. This pressure reduction effect is caused by the different diameter piston 24
An arbitrary size can be determined by appropriately determining the shape of the small diameter portion 24A.

When the rotation of the wheel 32 is restored and the acceleration of the vehicle reaches a certain predetermined value, the coil 31 is demagnetized by a degaussing signal from the control circuit 34, the switching valve 27 returns to its original position, and the right end of the different diameter piston 24 Aperture part 1
The hydraulic pressure on the upstream side _A1 of 2 acts again and the check valve 22 opens.

Then, when the wheel 32 is about to lock again, the excitation signal is applied to the coil 31 again, which is repeated, and as a result, the wheel 32 is braked with the maximum braking force that can prevent the wheel from locking. .

Note that when the coil 31 is demagnetized, the hydraulic pressure on the upstream side _A1 of the throttle section 12 is normally maintained in an increased state, so when the hydraulic fluid supply passage 28 opens, the right end of the different diameter piston 24 The increased hydraulic pressure will act on the surface, and as a result, the different diameter piston 24 will return quickly. Therefore, the responsiveness of hydraulic pressure control is improved.

2 and 3 respectively show other embodiments of the present invention, and in these figures, the first
Components with the same reference numerals as those in the figures are the same as those in the above embodiment. In a broad sense, these two embodiments include a valve device 36 disposed in the middle of the third hydraulic fluid passage C that closes the middle of the third hydraulic fluid passage 28 when the pressure in the hydraulic fluid supply passage 28 is below a certain level. If the pump 11 stops due to a failure or the like during braking, the valve device 36 is activated to maintain a constant braking force.

To explain the embodiment shown in FIG. 2 in more detail, here, a cut valve 37 is provided in the middle of the third oil passage C, and this cut valve 37 The spring 38 is biased in a direction to stop the flow in the return direction. The third oil passage C on the downstream side of the cut valve 37 when the liquid returns.
One end of a small diameter cylinder hole 39 is connected to the other end of the small diameter cylinder hole 39, and the other end of a large diameter cylinder hole 40 is connected to the hydraulic fluid supply passage 28 via a passage 41.

Reference numeral 42 denotes an auxiliary first piston, which includes a large diameter portion 42A that is slidably fitted into the large diameter cylinder hole 40 and a small diameter portion 4 that is slidably fitted into the small cylinder hole 39.
2B, and a projection 42C that can come into contact with the cut valve 37 is provided at the tip of the small diameter portion 42B. 43 and 44 are seal rings. The auxiliary first piston 42 is urged by a spring 45 in a direction away from the cut valve 37. The valve device 36 is constituted by the elements indicated by numerals 37 to 45 above.

In this embodiment, when the pump 11 is operating normally, the hydraulic pressure guided from the upstream side A ₁ of the throttle section 12 to the hydraulic fluid supply passage 28 acts on both ends of the auxiliary first piston 42; Due to the difference in pressure receiving area between the large diameter part 42A and the small diameter part 42B, the cut valve 37
The pushing force to the side becomes large, and the auxiliary first piston 42
The cut valve 37 is pushed toward the cut valve 37 by overcoming the force of the springs 45 and 38 and keeps the cut valve 37 open. Therefore, during operation of the pump, the same effect as in the above embodiment is performed.

On the other hand, if the pump 11 stops due to a failure or the like during braking and no hydraulic pressure is generated on the upstream side of the throttle valve 12, no hydraulic pressure acts on both ends of the auxiliary first piston 42, and the piston 42 Spring 45,3
8, the cut valve 37 closes the middle of the third oil passage C. Therefore, the large diameter cylinder chamber 21 is in a sealed state.

In such a state, the different diameter piston 24 tries to move toward the large diameter cylinder chamber 21 due to the brake fluid pressure increased by the use of the brake pedal 4, but the large diameter cylinder chamber 21 becomes a sealed chamber. Therefore, the different diameter piston 24 cannot move, and therefore the check valve 22 is kept open. Therefore, the brake fluid pressure from the master cylinder 15 continues to act on the wheel brakes 17, and the braking operation is maintained safely.

Next, the embodiment shown in FIG. 3 will be described in detail. Here, one end of a small diameter cylinder hole 46 is connected in the middle of the third oil passage C, and a cut valve 47 is connected to the small diameter cylinder hole 46. is provided. This cut valve 47 is biased by a spring 48 in the direction of opening the third oil passage C. One end of a large-diameter cylinder hole 49 is connected to the other end of the small-diameter cylinder hole 46, and the large-diameter cylinder hole 49 and the hydraulic fluid supply passage 28 are connected to each other via a passage 50 that opens on this one end surface. .

Reference numeral 51 denotes an auxiliary first piston, which includes a large diameter portion 15A that is slidably fitted into the large diameter cylinder hole 49 and a small diameter portion 5 that is slidably fitted into the small diameter cylinder hole 46.
1B. 52 and 53 are seal rings.

54 is a brake fluid chamber, one end of which is connected to the middle of the second oil fluid passage B on the upstream side of the check valve 22;
The other end opens at the other end of the large diameter cylinder hole 49 (the left end in the figure). There is an auxiliary second brake fluid in the brake fluid chamber 54.
A piston 55 is slidably housed, and is biased by a spring 56 in a direction to press the auxiliary first piston 51 toward the cut valve 47 side.
57 is a seal ring. The valve device 36 is constituted by the elements indicated by numerals 46 to 57 above.

In this embodiment, when the pump 11 is operating normally, the hydraulic pressure on the upstream side _A1 of the throttle section 12 is transferred from the hydraulic fluid supply passage 28 to the large diameter section 51A of the second auxiliary piston 51 via the passage 50. It is acting on the right end. On the other hand, during braking, the auxiliary second piston 55
The brake fluid pressure and the spring force of the spring 56 are acting to the right. However, due to the difference between the rightward pushing force of the auxiliary first piston 51 and the leftward pushing force of the auxiliary second piston 55, the auxiliary first piston 51 is maintained in a state of being pushed leftward, and this causes the cut valve to open. 47 keeps the third oil passage C open. Therefore, when pump 11 is in normal operation, the device operates similarly to the embodiment shown in FIG.

When the pump 11 stops, the upstream side of the throttle section 12
No hydraulic pressure is generated at _A1 , so the force of the brake fluid pushing the second auxiliary piston 55 to the left is greater than the force of the hydraulic fluid pushing the first auxiliary piston 51 to the left. The pistons 55, 51 are pushed to the right and press the cut valve 47 to the closing side. As a result, the cut valve 47 closes the middle of the third oil passage C to bring the large diameter cylinder chamber 21 into a sealed state. Therefore, the different diameter piston 24 pushes the check valve 22 open and keeps the brake fluid pressure from the master cylinder 15 acting on the wheel brakes 17 to maintain the braking state.

In addition, when the pump 11 is stopped before the start of braking, both pistons 5 are
5, 51 are pushed to the right, and the cut valve 47 is kept closed. Therefore, the large diameter cylinder chamber 2
1 is kept in a sealed state, and the check valve 22 is kept in an open state. Therefore, a braking action can be performed.

In this embodiment, in the valve device 36, the cut valve 47, the auxiliary first piston 51, and the auxiliary second piston 55 are formed separately.
The tip of the small diameter portion of the piston 51 (the right end in the figure) itself may serve as the cut valve 47. In this case, the spring 48 is not required. Further, the first auxiliary piston and the second auxiliary piston may be formed integrally.

In the embodiment shown in FIG. 3, an air bleed valve 58 is provided at the outer opening of the hydraulic fluid return passage 29.
are screwed together so that they can move forward and backward, and the hydraulic fluid return passage 2
9 is a passage 59 formed in the air bleed valve 58
It is connected to piping 35 via. Further, the large diameter cylinder portion 21 is connected to the hydraulic fluid return passage 29 via a passage 60, and the air bleed valve 58 is normally connected to the hydraulic fluid return passage 29 by the valve head 58A of the air bleed valve 58. Communication has been cut off.
Therefore, the third oil passage C is opened by the valve device 36.
When the cylinder is closed, the inside of the large-diameter cylinder chamber 21 becomes a sealed chamber as described above. However, if air or the like is present in the large diameter cylinder chamber 21, the different diameter piston 24 may be moved to the right when the pump is stopped, which may close the check valve 22 and prevent the braking action from being performed. To prevent such a risk, when air or the like is present in the large diameter cylinder chamber 21, the air bleed valve 58 is loosened to allow the passages 60 and 29 to communicate with each other. As a result, the air and the like in the large diameter cylinder chamber 21 are returned to the suction side of the pump 11 from the passage 60 through the passages 29, 59 and the piping 35 together with the working fluid, and the air and the like are removed.

In the case of the above configuration, unlike the case where an air bleed valve is provided directly in the large-diameter cylinder chamber 21 to release air, etc. to the outside, there is almost no loss of hydraulic fluid, there is no need to replenish the pump with hydraulic fluid, and there is no air bleed valve. This eliminates the need to separately connect an air vent hose to the valve or prepare a tray to receive hydraulic oil. Further, since there is no external leakage of the hydraulic fluid, there is no risk of it mixing with the brake fluid, and there is no risk of sealing failure of the sealing material due to mixing.

It goes without saying that the air bleed valve shown in this embodiment can be incorporated into the apparatus of the embodiment shown in FIG.

Although each of the embodiments has been described above, the present invention is applicable to connecting the hydraulic fluid supply passage to the upstream side of the throttle part in the first oil passage in the main body of the hydraulic pressure booster.
It goes without saying that the present invention is not limited to the embodiments described above. For example, a structure in which the hydraulic booster body and the hydraulic control unit body are formed separately, and the hydraulic fluid supply passage is connected to the middle of the first oil passage on the upstream side of the throttle part via piping. It may be.

As is clear from the above description, the present invention has a structure in which the hydraulic fluid supply passage is connected to the middle of the first oil passage on the upstream side of the throttle part in the main body of the hydraulic pressure booster, so that two conventional oil supply passages are required. This makes it possible to reduce the number of pumps that used to be used, thereby reducing the number of parts and the installation space on the vehicle. In addition, since the hydraulic pressure acting on the right end surface of the different diameter piston when the anti-skid is not activated can be increased in response to the increase in brake hydraulic pressure caused by brake operation, stable hydraulic pressure control can be performed. become able to.

In addition, the present invention provides a system in which when the pressure in the hydraulic fluid supply passage becomes below a certain level in the middle of the third hydraulic fluid passage that connects the large diameter cylinder chamber in the hydraulic pressure control unit main body and the hydraulic fluid supply passage. Since the structure is equipped with a valve device that closes the passage, even if the pump or the like breaks down during braking and the pressure in the large diameter cylinder chamber decreases,
By operating the valve device, a constant pressure is ensured within the large diameter cylinder chamber and braking force is maintained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a hydraulic brake drive device showing an embodiment of the present invention. FIGS. 2 and 3 are sectional views showing other embodiments of the present invention, respectively. 1... Hydraulic pressure booster body, 2... Hydraulic pressure control unit body, 4... Brake pedal, 5... Input rod, 6... Output rod, A...
1st oil passage, 12... Throttle part, 15... Master cylinder, 16... Discharge port, 17... Wheel brake, B... Second oil passage, 20... Small diameter cylinder chamber, 21... Large Diameter cylinder chamber, 22... Check valve, 24... Different diameter piston, C... Third oil passage, 27... Switching valve, 28... Hydraulic fluid supply passage, 29... Hydraulic fluid return passage, 32... ...wheels, 3
6... Valve device.

Claims (1)

[Scope of Claims] 1. A hydraulic brake drive device having a hydraulic pressure booster main body and a hydraulic pressure control unit main body, wherein hydraulic fluid discharged from a pump is supplied to the hydraulic pressure booster main body. A first oil passage leading to the suction side, an input rod that slides in conjunction with a brake pedal and has a control part that controls the flow of oil in the middle of the first oil passage, and is controlled by the control part. and an output rod that is driven by the hydraulic pressure generated by the hydraulic pressure and acts on the piston in the master cylinder. 2 oil passages, a small-diameter cylinder chamber that opens midway through the second oil passage, a large-diameter cylinder chamber following the small-diameter cylinder chamber, and a large-diameter cylinder chamber provided upstream of the small-diameter cylinder chamber midway through the second oil passage. A check valve, a deformed piston having one end fitted into the large diameter cylinder chamber and the other end fitted into the small diameter cylinder chamber and having a protrusion on the other end that abuts the check valve, and connected to the large diameter cylinder chamber. When a detection signal is not output from the third oil passage and the lock detection unit that detects the lock of the wheel, the third oil passage and the hydraulic fluid supply passage are connected, and a detection signal is output from the lock detection unit. a switching valve that connects the third hydraulic fluid passage and the hydraulic fluid return passage when the hydraulic fluid supply passage is switched, and connects the hydraulic fluid supply passage to an upstream side of the control section of the hydraulic pressure booster main body. A hydraulic brake drive device, characterized in that it is connected in the middle of a first oil passage. 2. The hydraulic brake drive device according to claim 1, wherein the hydraulic pressure booster main body and the hydraulic pressure control unit main body are integrally formed. 3. A hydraulic brake drive device having a hydraulic pressure booster main body and a hydraulic pressure control unit main body, wherein the hydraulic pressure booster main body has a first valve that guides the hydraulic fluid discharged from the pump to the suction side of the pump. an input rod having an oil passage, a control part that slides in conjunction with a brake pedal and controls the flow of oil in the middle of the first oil passage; and hydraulic pressure generated under control of the control part. an output rod that is driven by the output rod to act on the piston in the master cylinder, and a second oil passageway in the hydraulic control unit body that guides the brake fluid discharged from the discharge port of the master cylinder to the wheel brakes; A small-diameter cylinder chamber that opens in the middle of the second oil passage, a large-diameter cylinder chamber that follows the small-diameter cylinder chamber, and a check valve provided on the upstream side of the small-diameter cylinder chamber in the middle of the second oil passage; A deformed piston that fits into the large-diameter cylinder chamber and whose other end fits into the small-diameter cylinder chamber and has a protrusion on the other end that abuts the check valve, and a third oil passage connected to the large-diameter cylinder chamber. The third oil passage and the hydraulic fluid supply passage are connected when a detection signal is not outputted from the lock detection unit that detects the lock of the wheels, and switched when a detection signal is output from the lock detection unit. a switching valve connecting the third oil passageway and the hydraulic fluid return passage; and connecting the hydraulic fluid supply passageway to the middle of the first oil passageway upstream of the control section of the hydraulic pressure booster main body. A hydraulic brake drive device, further comprising a valve device that is connected to the third oil passageway and closes an intermediate portion of the third oil passageway when the pressure in the third oil passageway is below a certain level. 4. The valve device includes a cut valve provided in the middle of the third oil passage and biased by a spring in a direction to close the third oil passage, and a third oil passage on the downstream side of the cut valve when liquid returns. a small-diameter cylinder hole connected to the small-diameter cylinder hole, and a large-diameter cylinder hole that follows the small-diameter cylinder hole and is connected to the working fluid supply passage, one end of which fits into the large-diameter cylinder hole and the other end of which fits into the small-diameter cylinder hole. The auxiliary first piston is composed of an auxiliary first piston having a protrusion that can come into contact with the cut valve at the other end thereof, and a spring that biases the auxiliary first piston in a direction to separate the auxiliary first piston from the cut valve. Claim 3, wherein the piston is formed so that when the hydraulic pressure in the hydraulic fluid supply passage is above a certain level, the piston is pushed toward the cut valve by the hydraulic pressure to maintain the cut valve in an open state. Hydraulic brake drive device. 5. The valve device includes a small diameter cylinder hole connected in the middle of the third oil passage, a cut valve provided in the small diameter cylinder hole and biased by a spring in a direction to open the third oil passage, and a small diameter cylinder hole connected in the middle of the third oil passage. a large diameter cylinder hole following the cylinder hole and connected to the hydraulic fluid supply passage;
An auxiliary whose one end fits into a large-diameter cylinder hole and the other end fits into a small-diameter cylinder hole, and which is pushed away from the cut valve by the hydraulic pressure when the hydraulic pressure in the hydraulic fluid supply passage is above a certain level. a first piston, a brake fluid chamber having one end connected to the second oil passage upstream of the check valve and the other end connected to the large diameter cylinder hole; The hydraulic brake drive device according to claim 3, comprising: an auxiliary second piston biased by a spring in a direction that presses the piston toward the cut valve side. 6. The hydraulic brake drive device according to claim 3, wherein the hydraulic pressure booster body and the hydraulic control unit body are integrally formed.