JP2006160134A - Braking device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To individually and easily adjust relationship between a stroke and reaction force in a stroke simulator, and a hysteresis characteristic at the time of brake operation and brake release. <P>SOLUTION: A braking device for a vehicle is provided with a bellows member 4 with one end side fixed on a push rod 3 and with the other end side fixed on a building frame of a master cylinder 2, extending according to retreat of the push rod 3 while contracting according to advance of the push rod 3; and a pair of magnets 5 provided on a bellows wall adjacent thereto when the bellows member 4 is contracted, to attract each other by magnetic force. Thereby, large force is required when extension of the bellows member 4 from a contracted state thereof is suppressed, or when the bellows member 4 is extended from the contracted state rather than when the bellows member 4 is contracted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle brake device including a stroke simulator that generates an appropriate stroke and reaction force in response to a driver's brake operation.

In general, the brake-by-wire using a hydraulic circuit normally transmits the hydraulic pressure according to the brake operation to the wheel cylinder by a pump or the like in a state where the hydraulic pressure path from the master cylinder to the wheel cylinder is interrupted. The hydraulic pressure path from the master cylinder to the wheel cylinder is opened, and the hydraulic pressure corresponding to the brake operation is transmitted from the master cylinder to the wheel cylinder.
In such a brake system, when the hydraulic pressure path from the master cylinder to the wheel cylinder is interrupted, it can be elastically contracted so that an appropriate pedal stroke and pedal reaction force are generated for the driver's brake operation. A stroke simulator is provided.

By the way, in a conventional brake system that supplies hydraulic pressure corresponding to the pedal depression force to the wheel cylinder through a booster (boost device), the hysteresis characteristic is related to the relationship between the pedal depression force and the braking force due to the characteristic of the booster. There is. That is, when the pedal depression force is reduced from the state where the brake pedal is depressed, the braking force decreases with a delay with respect to the decrease in the pedal depression force, and the braking force is maintained even if the pedal depression force is reduced. Pedal feeling can be obtained.
In view of this, a stroke simulator has been proposed in which a hysteresis characteristic can be obtained when the pedal is depressed and when the pedal is returned even in a system that performs brake-by-wire (see Patent Document 1).

In this stroke simulator, a spring member that is elastically contracted in accordance with a driver's brake operation has a structure in which a plurality of disc springs are overlapped. Accordingly, when the spring member is elastically contracted when the pedal is depressed, the contact area between the disc springs is increased, the sliding resistance is increased, and the spring member is difficult to be restored when the pedal is returned, so that a hysteresis characteristic is obtained. The hysteresis characteristic is adjusted by changing the number of disc springs.
Japanese Patent Laid-Open No. 6-211124

  Incidentally, in the stroke simulator, the relationship between the pedal stroke and the pedal effort is determined by the spring constant (elastic coefficient) of the spring member. Therefore, as in the conventional example described in Patent Document 1, when the number of disc springs is changed in order to adjust the hysteresis characteristics, the spring constant of the entire spring member changes, so that the pedal stroke and the pedal effort are reduced. The relationship will also change.

Also, as the pedal depression force increases, the pressing force between the disc springs also increases. Depending on the number of disc springs and the friction coefficient, the disc springs may be fixed and integrated in a region where the pedal depression force is large. Therefore, a desired hysteresis characteristic is not always obtained.
For this reason, in the stroke simulator described in Patent Document 1, it is difficult to individually adjust the relationship between the pedal stroke and the pedal effort and the hysteresis characteristics, and it is particularly difficult to adjust the hysteresis characteristics. .
Accordingly, the present invention has been made paying attention to the above problems, and it is possible to easily and individually adjust the relationship between the stroke and the reaction force in the stroke simulator and the hysteresis characteristics at the time of brake operation and release of the brake. Providing a device is an issue.

  In order to solve the above-described problems, a vehicle brake device according to the present invention includes a rod that advances and retreats according to a driver's brake operation, a stroke simulator that elastically contracts according to advancement of the rod, and one end side of the rod. The bellows member is fixed, and the other end side is fixed to a stationary member that does not move with respect to the advancement / retraction of the rod. The bellows member contracts according to the advancement of the rod and extends according to the retraction of the rod. It is characterized by suppressing the extension from the state or by requiring a larger force when extending from the contracted state than when the bellows member contracts.

Here, when the stroke simulator elastically contracts, a stroke and a reaction force against the driver's braking operation are generated.
Moreover, if the expansion | swelling from the state which the bellows member contracted is suppressed, the retreat | retreat from the state which the rod also moved forward will be suppressed, and the hysteresis characteristic at the time of brake operation and a brake release will be acquired. In addition, if a larger force is required when the bellows member is extended from the contracted state than when the bellows member is contracted, the rod also requires a larger force when retracting from the advanced state than when moving forward. And hysteresis characteristics when the brake is released.

  According to the vehicle brake device of the present invention, the relationship between the stroke and the reaction force in the stroke simulator depends on the elastic coefficient of the stroke simulator itself, and the hysteresis characteristics at the time of one brake operation and release of the brake are Depends on the difficulty of stretching. Therefore, the relationship between the stroke and the reaction force in the stroke simulator, and the hysteresis characteristics at the time of brake operation and at the time of brake release can be individually and easily adjusted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a brake system. When a pedal depression force is input to one end of the brake pedal 1 that is braked by the driver, the brake pedal 1 rotates around the other end to advance the push rod 3 (rod) of the master cylinder 2.
The push rod 3 has one end fixed to the push rod 3 and the other end inserted through a rubber bellows member 4 fixed to the housing (non-moving member) of the master cylinder 2. Therefore, the bellows member 4 contracts when the push rod 3 advances, and extends when the push rod moves backward from the advanced state.

  Further, as shown in FIG. 2, the bellows member 4 is fixed to the push rod 3 and the master cylinder 2 in the radial direction of the adjacent bellows wall when contracting, that is, here, the valley folds 4a ( A magnet 5 (magnetic body, expansion / contraction characteristic changing means) is embedded in a mountain fold portion on the inner peripheral surface, and an adjacent pair of magnets 5 have an S pole and an N pole so that they attract each other by magnetic force. It is arranged in the opposite direction. However, since the magnitude of the magnetic force is inversely proportional to the distance between the magnetic poles, they are not attracted to each other under the influence of the magnetic force until the magnets 5 approach to some extent.

Then, as shown in FIG. 1, the master cylinder 2 converts the pedal depression force input via the push rod 3 into two systems of hydraulic pressure, and transmits the primary side to the rear left and right wheel cylinders 6RL and 6RR. The secondary side is transmitted to the front left and right wheel cylinders 6FL and 6FR. Here, a front / rear split system in which the brake system is divided by front and rear wheels is adopted, but of course, a diagonal split system in which the brake system is divided by front left and rear right and front right and rear left may be adopted.
Each of the wheel cylinders 6FL to 6RR is incorporated in a disc brake that presses a disc rotor with a brake pad to generate a braking force, or a drum brake that generates a braking force by pressing a brake shoe against the inner peripheral surface of the brake drum. Yes.

  In the hydraulic system on the primary side, a gate valve 7r that can close the flow path between the master cylinder 2 and the wheel cylinders 6RL and 6RR, and an inlet valve that can close the flow path between the gate valve 7r and the wheel cylinder 6RL (6RR) 8RL (8RR), an outlet valve 8RL (8RR), an outlet valve 9RL (9RR) capable of opening a flow path communicating between the inlet cylinder 8RL (8RR) and the wheel cylinder 6RL (6RR) and the reservoir tank 2a of the master cylinder 2; 9RR and the reservoir tank 2a, and the pump 10r which connected the discharge side between the gate valve 7r and the inlet valves 8RL and 8RR.

  Here, the gate valve 7r, the inlet valves 8RL and 8RR, and the outlet valves 9RL and 9RR are two-port, two-position switching, spring-offset type electromagnetic operation valves, respectively. The gate valve 7r and the inlet valves 8RL and 8RR are The flow path is opened at the non-excited normal position, and the outlet valves 9RL and 9RR are configured to close the flow path at the non-excited normal position. Since each valve only needs to be able to open and close the flow path, the gate valve 7r and the inlet valves 8RL and 8RR open the flow path at the excited offset position, and the outlet valves 9RL and 9RR are excited. The flow path may be closed at the position.

The pump 10r is configured by a positive displacement pump such as a gear pump or a piston pump that can secure a substantially constant discharge amount regardless of the load pressure.
With the above configuration, the reservoir valve tank 8r (8RR) and the outlet valve 9RL (9RR) are kept in a non-excited normal position, the gate valve 7r is excited and closed, and the reservoir tank is driven by driving the pump 10r. The brake fluid of 2a is sucked and the hydraulic pressure of the wheel cylinder 6RL (6RR) can be increased by the discharge pressure.

Further, by energizing the gate valve 7r and the inlet valve 8RL (8RR) while closing the outlet valve 9RL (9RR) at the non-excited normal position, the reservoir tank 2a and the reservoir tank 2a and the wheel cylinder 6RL (6RR) are closed. Each flow path to the pump 10r can be blocked, and the hydraulic pressure of the wheel cylinder 6RL (6RR) can be maintained.
Further, the outlet valve 9RL (9RR) is excited and opened, and the gate valve 7r and the inlet valve 8RL (8RR) are excited to close each other, whereby the hydraulic pressure of the wheel cylinder 6RL (6RR) is reduced to the reservoir tank 2a. And can be decompressed.

Furthermore, the hydraulic pressure from the master cylinder 2 is transmitted to the wheel cylinder 6RL (6RR) by setting all of the gate valve 7r, the inlet valve 8RL (8RR), and the outlet valve 9RL (9RR) to the non-excited normal position. It becomes a normal brake.
Note that the secondary hydraulic system also includes the same gate valve 7f, inlet valves 8FL and 8FR, outlet valves 9FL and 9FR, and pump 10f as the primary side, and each operation is the same as the primary side. Detailed description thereof will be omitted.

A stroke simulator 11 is connected between the master cylinder 2 and the gate valve 7r on the primary side. The stroke simulator 11 is constituted by a spring-type accumulator having a compression spring 11a interposed between the bottom of the cylinder and a piston, and the compression spring 11a elastically contracts as the hydraulic pressure increases.
A gate valve 12 is interposed between the master cylinder 2 and the stroke simulator 11. This gate valve 12 is a two-port, two-position switching, spring offset type electromagnetically operated valve, and is configured to close the flow path at a non-excited normal position. Since the gate valve 12 only needs to be able to open and close the flow path, the flow path may be closed at the excited offset position.

  The gate valves 7f and 7r, the inlet valves 8FL to 8RR, the outlet valves 9FL to 9RR, the pumps 10f and 10r, and the gate valve 12 are controlled by the controller 13 and normally close the gate valves 7f and 7r. At the same time, the gate valve 12 is opened, and braking force control (brake-by-wire) is performed according to the amount of brake operation of the driver detected by a stroke sensor (not shown). On the other hand, at the time of fail-safe such as a pump failure, the gate valves 7f and 7r are opened, the gate valve 12 is closed, and the hydraulic pressure from the master cylinder 2 is transmitted to the wheel cylinders 6FL to 6RR to make a normal brake.

Next, operations and effects of the first embodiment will be described.
Suppose now that normal brake-by-wire is performed. That is, with the gate valve 12 opened, the gate valves 7f and 7r are closed, and the inlet valves 8FL to 8RR, the outlet valves 9FL to 9RR, and the pumps 10f and 10r are driven and controlled according to the driver's brake operation. Adjust the target wheel cylinder pressure.

At this time, as the push rod 3 moves forward according to the pedaling force of the driver, hydraulic pressure is generated in the master cylinder 2 and transmitted to the stroke simulator 11. Thereby, since the stroke simulator 11 is elastically contracted, an appropriate pedal stroke and pedal reaction force are generated for the driver's braking operation.
Further, when the bellows member 4 contracts from the initial state as the push rod 3 advances, the bellows member 4 contracts according to the driver's pedaling force and the attractive force of the pair of magnets 5 until each pair of magnets 5 comes into contact. It will be. Therefore, when the pedal is stepped on, the pedaling force is assisted by the attractive force of the pair of magnets 5, and therefore the pedaling force can be reduced.

  When the pair of magnets 5 are in contact with each other, when the push rods 3 are retracted, the pair of magnets 5 are less likely to be stretched by the magnetic force attracting each other. That is, the magnet 5 disposed in the valley fold portion 4a of the bellows member 4 suppresses the expansion of the bellows member 4 from the contracted state, or extends from the contracted state than when the bellows member 4 contracts. Sometimes great power is required.

  Therefore, if the expansion from the contracted state of the bellows member 4 is suppressed, the push rod 3 is also prevented from retreating from the advanced state, and a hysteresis characteristic when the pedal is depressed and when the pedal is returned is obtained. Further, when a large force is required when the bellows member 4 is expanded from the contracted state than when the bellows member 4 is contracted, the push rod 3 also requires a large force when retracting from the advanced state than when moving forward, Hysteresis characteristics can be obtained when the pedal is depressed and when the pedal is released. The pair of magnets 5 are attracted to each other as long as they approach each other even if they do not necessarily contact each other, so that the above hysteresis is maintained even if the bellows member 4 does not contract until the pair of magnets 5 contact each other. Characteristics can be obtained. Thus, when the pedal effort is decreased from the state where the brake pedal is depressed, the braking force decreases with a delay relative to the decrease in the pedal effort, and the braking force is maintained even if the pedal effort is reduced, which is good. Pedal feeling can be obtained.

  Thus, the relationship between the pedal stroke and the pedal reaction force in the stroke simulator 11 depends on the elastic coefficient of the stroke simulator 11 itself, that is, the spring constant of the compression spring 11a. On the other hand, the hysteresis characteristic when the pedal is depressed and when the pedal is returned depends on the difficulty of expansion of the bellows member 4, that is, the magnitude of the magnetic force in the magnet 5 and the number thereof. Therefore, the relationship between the pedal stroke and the pedal reaction force in the stroke simulator 11 and the hysteresis characteristics when the pedal is depressed and when the pedal is returned can be easily and individually adjusted.

Further, since the difficulty of extending the bellows member 4 is realized by a pair of magnets 5 that attract each other by magnetic force, it is easy to adjust the hysteresis characteristics simply by changing the magnitude and the number of the magnets 5. Can be done.
Further, when the bellows member 4 contracts, the magnet 5 is embedded in the valley fold portion 4a on the side fixed to the push rod 3 and the master cylinder 2 in the radial direction of the adjacent bellows wall. Can be minimized, and the expansion of the bellows member 4 can be effectively suppressed. In particular, since the rubber bellows member 4 is highly flexible as in this embodiment, the outer side of the bellows wall is fixed to the push rod 3 and the master cylinder 2 in the radial direction. When the magnet 5 is embedded in the portion 4b (in the inner peripheral surface, the valley folding portion), when trying to suppress the expansion of the bellows member 4, the valley folding side of the bellows wall is bent and extends, and the bellows member 4 extends. This is because it cannot be effectively suppressed.

When, for example, a pump failure occurs from the state where the brake-by-wire is performed, the gate valves 7f and 7r are opened by fail-safe, and the braking force is generated by the hydraulic pressure of the master cylinder 2.
Also at this time, the hysteresis characteristic when the pedal is depressed and when the pedal is returned can be obtained in the same manner as when performing brake-by-wire.

  In the first embodiment, the magnet 5 is embedded only in the valley fold portion 4a of the bellows wall. However, the present invention is not limited to this. Of course, the magnet 5 may be embedded in the mountain folding side of the bellows wall. Good. Here, as described above, the magnet 5 is embedded in the valley folding portion 4a of the bellows wall. As described above, the push rod 3 and the master cylinder 2 are connected to the valley folding side (in the inner circumferential surface of the bellows wall). This is because the mountain folding side is fixed. Therefore, as shown in FIG. 3, the flange 3a formed on the push rod 3, the flange 2b connected to the housing of the master cylinder 2, and the fold-fold side of the outer peripheral surface of the bellows wall (the valley fold on the inner peripheral surface). When the side) is fixed, each magnet 5 may be embedded in the mountain fold 4b of the bellows wall.

Moreover, in said 1st Embodiment, although a pair of adjacent magnetic body is made into the magnet which consists of a hard magnetic body, it is not limited to this. In short, since it is only necessary to be attracted by a magnetic force, if at least one is a magnet, the other may be a magnetic body such as iron, nickel, or cobalt.
Moreover, in said 1st Embodiment, although the rubber-made bellows member 4 is used, it will not be limited to this, What kind of material may be used if it is a telescopic bellows member.
Moreover, in said 1st Embodiment, although the other end of the bellows member 4 is being fixed to the housing of the master cylinder 2, it is not limited to this, The immovable member which does not move with respect to advance / retreat of the push rod 3 If so, it may be fixed to other vehicle body components.

  Furthermore, in said 1st Embodiment, although the both ends of the bellows member 4 are being fixed to the push rod 3 and the housing of the master cylinder 2, it is not limited to this. In short, since both ends of the bellows member 4 may be fixed to a rod that advances and retreats according to the driver's brake operation and a stationary member that does not move with respect to the advance and retreat of the rod, for example, as shown in FIG. You may make it fix the both ends of the bellows member 4 to the output rod 11b which protrudes when the compression spring 11a of the simulator 11 elastically contracts, and the cylindrical rigid body 11c connected to the housing of the stroke simulator 11.

  In this case, since the piston of the stroke simulator 11 is difficult to return when the pedal is returned, the hydraulic fluid returning from the stroke simulator 11 to the master cylinder 2 is also difficult to return, and the piston of the master cylinder 2 is also difficult to return. Since a cup seal (one-way seal) is used as the piston seal member, if the amount of hydraulic fluid returning from the stroke simulator 11 to the master cylinder 2 is insufficient with respect to the pedal return amount, the reservoir 2a passes through the cup seal. It is considered that the hysteresis of the actual pedal operation is reduced because the brake pedal 1 returns in a straight direction by supplying the hydraulic fluid. Therefore, as shown in FIGS. 1 and 2, if the bellows member 4 is provided at the push rod 3 between the master cylinder 2 and the brake pedal 1, such hysteresis can be prevented from being reduced. It can be said that this is a more preferable embodiment.

In the first embodiment, the hydraulic brake using the hydraulic pressure as the transmission medium is employed. However, the present invention is not limited to this, and an air brake using the compressed air as the transmission medium may be employed. Good.
Furthermore, in said 1st Embodiment, although the brake-by-wire using a fluid pressure is performed, it is not limited to this. Since it is only necessary to be able to control the braking force for the brake-by-wire, an electric brake that clamps the disc rotor with the brake pad or presses the brake shoe against the inner peripheral surface of the brake drum by controlling the driving of the electric actuator. Any brake may be used as long as it has an electronically controllable energy source such as a regenerative motor brake.
In the first embodiment, the brake-by-wire is performed according to the brake operation amount detected by the stroke sensor. However, the present invention is not limited to this, and the brake-by-wire is determined according to the pedal depression force detected by the pressure sensor. May be performed.

Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, as shown in FIG. 3, in order to suppress the expansion of the bellows member 4, hook and loop fasteners 14 (extension / stretch characteristic change) that can be engaged with a magic tape (registered trademark), that is, a pair of hooks and piles. Except for the fact that the means) is affixed, the configuration is the same as that of the first embodiment. Therefore, the same reference numerals are given to the corresponding parts to those of the first embodiment, and the detailed description thereof is omitted.

Here, the hook-and-loop fastener 14 is affixed to the push rod 3 and the master cylinder 2 in the radial direction of the inner peripheral surface of the bellows member 4, that is, here on the mountain-folded portion 4 a side of the inner peripheral surface. The pair of hook surfaces and the pile surface are arranged so as to face each other.
Therefore, when the bellows member 4 contracts from the initial state as the push rod 3 moves forward, the bellows member 4 contracts according to the pedaling force of the driver until each surface fastener 14 comes into contact. Then, when each surface fastener 14 is in contact with the push rod, the surface fastener 14 is not easily extended due to the engaging force of the surface fastener 14.

Therefore, as in the first embodiment described above, hysteresis characteristics when the pedal is depressed and when the pedal is returned can be obtained.
Such hysteresis characteristics depend on the difficulty of expansion of the bellows member 4, that is, the magnitude of the hook and pile engaging force of the hook and loop fastener 14 and the area of the hook.
Therefore, the hysteresis characteristic can be easily adjusted only by changing the magnitude of the hook and pile engaging force of the hook-and-loop fastener 14 and the affixing area thereof.

Moreover, since the surface fastener 14 is affixed to the side fixed to the push rod 3 and the master cylinder 2 in the radial direction of the inner peripheral surface, that is, the mountain fold portion 4a side of the inner peripheral surface, the bellows member 4 is bent. It can be minimized, and the expansion of the bellows member 4 can be effectively suppressed. In particular, since the rubber bellows member 4 is highly flexible as in this embodiment, the opposite side of the inner peripheral surface fixed to the push rod 3 and the master cylinder 2 in the radial direction, that is, the inner peripheral surface here. If the surface fastener 14 is affixed to the side of the valley fold 4b, when the expansion of the bellows member 4 is to be suppressed, the mountain fold side of the inner peripheral surface is bent and extends, effectively suppressing the expansion of the bellows member 4. Because you can't.
Further, since the hook and loop fastener 14 is attached to the inner peripheral surface of the bellows member 4, it prevents adhesion of dust, dust, etc., and lowers the engaging force of the hook and the pile, rather than sticking to the outer peripheral surface of the bellows member 4. Can be prevented.

In addition, in said 2nd Embodiment, although the surface fastener 14 is stuck only in the mountain fold part 4a side of an internal peripheral surface, it is not limited to this, Of course, the valley fold part 4b of an internal peripheral surface You may affix on the side and also the outer peripheral surface. In particular, the leading end side of the valley surface of the bellows member 4, that is, the valley side of the inner peripheral surface and the valley side of the outer peripheral surface are the bellows walls compared to the mountain folding side of the inner peripheral surface and the mountain folding side of the outer peripheral surface. As shown in FIG. 6, for example, if a hook-and-loop fastener 14 is affixed to a mountain-folded region on the inner peripheral surface, the hook and pile are attached even if the stroke of the push rod 3 is small. Therefore, in addition to the effects described above, the hysteresis characteristic can be obtained even when the brake pedal 1 is further depressed.
Other functions and effects are the same as those of the first embodiment described above.
Further, the first and second embodiments may be combined.

It is a schematic block diagram of a brake system. It is a schematic block diagram of 1st Embodiment. It is a figure at the time of changing the embedding position of a magnet according to the fixing position of a bellows member. It is a figure at the time of attaching a bellows member to a stroke simulator. It is a schematic block diagram of 2nd Embodiment. It is a figure at the time of changing the sticking range of a hook-and-loop fastener.

Explanation of symbols

1 Brake pedal 2 Master cylinder 3 Push rod (rod)
4 Bellows member 4a Valley fold of outer circumferential surface, mountain fold of inner circumferential surface 4b Mountain fold of outer circumferential surface, valley fold of inner circumferential surface 5 Magnet (magnetic body, expansion / contraction characteristic changing means)
6FL to 6RR Wheel cylinder 7f and 7r Gate valve 8FL to 8RR Inlet valve 9FL to 9RR Outlet valve 10f and 10r Pump 11 Stroke simulator 11a Compression spring 12 Gate valve 13 Controller 14 Surface fastener (Expansion and contraction characteristic changing means)

Claims (8)

  A rod that advances and retreats according to the driver's brake operation, a stroke simulator that elastically contracts according to the forward movement of the rod, a fixed member whose one end is fixed to the rod, and the other end is immovable with respect to the advance and retreat of the rod And a bellows member that contracts as the rod advances and expands as the rod retreats, and expansion / contraction characteristic changing means that suppresses extension of the bellows member from the contracted state. Brake device for vehicles characterized.   A rod that advances and retreats according to the driver's brake operation, a stroke simulator that elastically contracts according to the forward movement of the rod, a fixed member whose one end is fixed to the rod, and the other end is immovable with respect to the advance and retreat of the rod And a bellows member that contracts as the rod advances and expands as the rod retracts, and requires a greater force when extending from the contracted state than when the bellows member contracts. And a telescopic characteristic changing means.   3. The vehicle according to claim 1, wherein the expansion / contraction characteristic changing unit is configured by at least a pair of magnetic bodies that are disposed on an adjacent bellows wall when the bellows member contracts, and attract each other by a magnetic force. Brake device.   4. The vehicle brake device according to claim 3, wherein the pair of magnetic bodies are disposed on a side fixed to the rod and the stationary member in a radial direction of the bellows wall.   The expansion / contraction characteristic changing means is configured by a surface fastener that is disposed on an adjacent bellows wall when the bellows member contracts and can be engaged with at least a pair of hooks and piles. 5. The vehicle brake device according to claim 4.   6. The vehicle brake device according to claim 5, wherein the surface fastener is disposed on a side fixed to the rod and the stationary member in a radial direction of the bellows wall.   The vehicular brake device according to claim 5 or 6, wherein the surface fastener is disposed on an inner peripheral surface of the bellows member.   The vehicular brake device according to any one of claims 5 to 7, wherein the surface fastener is disposed on a front end side of a valley fold surface in the bellows member.

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