JPH0443018B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brake device for automobiles, etc., and particularly to a brake device that facilitates starting on an uphill road.

[Conventional technology and its problems]

For example, in the brake device disclosed in Utility Model Application No. 55-43905, when the clutch pedal is depressed, a valve device linked to the clutch pedal is closed, and hydraulic pressure is applied to the wheel cylinder of a car on an uphill road. I'm trying to hold it and hold the brakes. That is, the driver can keep the car stopped on an uphill road even if he takes his foot off the brake pedal, but he must continue to press the clutch pedal.

When starting the car, the clutch pedal is gradually returned to a half-clutch state, and the accelerator pedal is depressed to increase the engine speed and start the car.

As mentioned above, when a car is stopped on an uphill road, the valve device is closed by depressing the clutch pedal, and the valve is opened by returning the clutch pedal to the point of starting.There is a relationship between this valve device and the clutch pedal. When various parts such as clutch facings wear out, the timing of opening the valve relative to the position of the clutch pedal is constant, but sufficient driving force is not transmitted from the engine to the wheels via the clutch facings to start the vehicle. The timing of the communication will be different. In other words, the brake, which allows sufficient driving force to be transmitted to the wheels, is released.

This is because, in the above-mentioned conventional system, the brake is released when the clutch pedal is in a position where the clutch device is in a so-called half-clutch state. This occurs because the position at which the clutch is in the half-clutch state changes, and the release timing is not changed in response to this change.

In this way, if the timing at which sufficient driving force is transmitted to the wheels and the timing at which the brakes are released deviate so that the latter is earlier and the former is slower, the vehicle will move backwards when starting on an uphill road. This may cause an accident.

In view of the above problems, we developed a pair of brake shoes for LT type drum brakes with the aim of providing a brake device that can perform appropriate operation according to the condition of the wheels or vehicle body when stopping and starting an automobile. between a wheel cylinder whose one end can be pushed toward the drum against the biasing force of a return spring, and a master cylinder where hydraulic pressure is generated by the driver's operation.
A solenoid valve is provided which is normally in a communication position and can be switched to a cutoff position in response to a command, so that an anchor member that the other ends of the pair of brake shoes abut can be moved within a predetermined range, and the A brake device has previously been proposed which is equipped with a switch that detects the displacement of the anchor member due to a change in the direction of frictional force acting between the anchor member and the brake shoe and issues a command to the solenoid valve. There is.

According to the above brake device, it is possible to maintain a stopped state of the vehicle even if the clutch pedal is not continuously depressed, and even if members such as the clutch plate are worn out, the pedal operation and the actual wheels or the vehicle body can be maintained. There is no possibility that the timing will be out of sync with the movement of the camera.

Furthermore, in the above device, the one end and the other end of the pair of brake shoes are biased in the direction of approaching each other by return springs, and the spring that biases the anchor member in one direction is also biased toward the other end. It is stretched between one end of the brake shoe and the back plate. This prevents the switch from malfunctioning due to rattling of the pair of brake shoes during driving.

However, in addition to the pair of return springs, there is also a spring for preventing rattling, so when applying the brakes, the hydraulic pressure in the wheel cylinder must be increased by overcoming the spring force of the pair of return springs and the rattling prevention spring. Must be. In other words, the force applied to the brake pedal increases.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above problems, and an object of the present invention is to provide a brake device that hardly increases the force applied to the brake pedal while preventing malfunction of the switch due to rattling.

[Means for solving problems]

The above purpose is to connect one end of a pair of LT drum brake shoes toward the drum against the biasing force of a return spring between the wheel cylinder, which can be pressed, and the master cylinder, which generates hydraulic pressure when operated by the driver. , a solenoid valve is provided which is normally in a communication position and can be switched to a cutoff position in response to a command, and a sliding anchor that the other ends of the pair of shoes abut can be moved within a predetermined range; In the brake device, the other end of the pair of shoes is provided with a switch that detects the displacement of the sliding anchor due to a change in the direction of action of the frictional force acting between the shoe and the shoe, and issues a command to the electromagnetic valve. Each shoe is biased toward the sliding anchor by a separate return spring, and the biasing force of the return spring provided for one of the pair of shoes, which becomes the leading shoe during forward movement, is applied to the other shoe. This is achieved by using a brake device whose biasing force is greater than the biasing force of the return spring provided against the brake.

[Effect]

When a car is stopped on an uphill road by applying the brakes, one shoe causes the sliding anchor to move in one direction. The switch detects this movement, closes the solenoid valve, and maintains hydraulic pressure in the brake system. In order to start the car, when a rotational force is applied to the wheels in the forward direction, the shoe moves the sliding anchor in the other direction. The switch detects this and opens the solenoid valve, releasing the hydraulic pressure in the brake system. In this way, the brake can be held and released depending on the condition of the wheels.

The other ends of the pair of shoes are biased toward the sliding anchor by separate return springs, and the biasing force of the return spring provided on one shoe, which becomes the leading shoe when moving forward, is applied to the return spring of the other shoe. Since the biasing force is made larger than the biasing force, it is possible to prevent the shoe from rattling due to vibration during driving and causing the switch to malfunction, and it also prevents the brake pedal from increasing the force applied when applying the brakes. It's not easy.

〔Example〕

First, before describing embodiments of the present invention, the operating principle and basic configuration of the present invention will be explained with reference to FIG.

In FIG. 1, it is assumed that a car is traveling on a slope S in the direction of arrow F. Therefore, wheel 1 is indicated by arrow A
rotating in the direction. As is well known, a wheel cylinder 2 is attached to a back plate 3 fixed to the vehicle body side.
is fixed, and a pair of bow-shaped shoes 4 are attached to this.
The upper ends of a and 4b are pivotally connected. Further, the lower end portion is in contact with both end portions 26a and 26b of the sliding anchor 6. The sliding anchor 6 is slidable into a through hole of an anchor body 7 fixed to the back plate 3, and protrusions 6a and 6b formed to protrude in the radial direction at both ends 26a and 26b contact the anchor body 7. By contacting them, the rightward forward movement position and leftward forward movement position of the sliding anchor 6 are regulated. In the figure, the left forward movement position is shown. As clearly shown in FIG. 2, the switch body 8 is housed within the anchor body 7, and the protrusion 6b of one end 26b abuts the switch actuator 9. The actuator 9 is biased to the left by a spring inside the main body 8, although not shown, and is off in the illustrated state.

The upper end portions of the shoes 4a, 4b are urged inward by the upper return spring 10a, and the lower portions each have one end connected to the anchor body 7.
It is urged inward by a pair of lower return springs 10b and 10c that are engaged with the central protrusion 7a. Lower right return spring 10c
The spring force is the lower return spring 10b on the right side.
is greater than the spring force of , which causes the sliding anchor 6
As shown in the figure, the projection 6a of the other end 26a of the anchor body 7 is constantly biased in the direction of contacting the anchor body 7, and prevents the switch from malfunctioning due to rattling when the shoe 4a, 4b is running. There is.

The brake configured as above is called
It is called the LT type drum brake, and one
A is called a leading show, and the other show 4b is called a trailing show. Now, when a brake pedal (not shown) is depressed to stop the automobile, pressurized fluid is supplied to the wheel cylinder 2, and the brake linings of the shoes 4a, 4b are pressed against the drum 5 that rotates together with the wheel 1. A frictional force is generated between the shoes 4a, 4b and the drum 5 in the direction opposite to the rotating direction of the drum 5 (direction of arrow A), and this provides a braking force, but it is of the same magnitude as the frictional force. The reaction force in the opposite direction acts as a brake reaction force as shown by arrows B and C,
The leading side shoe 4a comes into contact with the other end 26a of the sliding anchor 6 due to the sum of the pressing force and reaction force b from the piston in the wheel cylinder 2, and the trailing shoe 4b comes into contact with the other end 26b due to the difference. comes into contact with. Further, the leading side shoe 4a comes to contact the other end portion 26a more strongly due to the self-servo action. As a result, the force pushing the sliding anchor 6 to the left in the figure is greater, so the sliding anchor 6 continues to take the left forward movement position shown, and the switch 8 remains off.

When the car stops and the clutch is released, the wheel 1 receives a turning force in the direction opposite to arrow A due to gravity. That is, the vehicle is subjected to back torque that attempts to move it to a lower location. The direction of the frictional force acting between the shoes 4a, 4b and the drum 5 is reversed and becomes the direction of arrow B or C, but its magnitude is larger on the trailing shoe 4b side and the sliding anchor 6 slides to the right in the figure and assumes the right forward movement position. As a result, the actuator 9 of the switch 8 is pressed and turned "on". This "ON" signal causes a solenoid valve, which will be described later, to close, and the master cylinder side and the wheel cylinder 2 side are cut off, and the brake is maintained even if the foot is released from the brake pedal. The clutch pedal can be left in the neutral position with your foot removed.

When starting an automobile, the clutch pedal is depressed in a half-clutch state and the accelerator pedal is depressed, thereby transmitting driving torque to the wheels 1, that is, the drums 5 in the direction of arrow A. As a result, show 4
The frictional force between a, 4b and the drum 5 is reversed again, and a brake reaction force as shown by arrows B and C acts on the shoes 4a, 4b, and the sliding anchor 6 moves to the left, as shown in the figure. Takes the left forward movement position. That is, the switch 8 is turned off, the solenoid valve (not shown) is opened, and the master cylinder side and the wheel cylinder 2 side are in communication. In this way, the hydraulic pressure in the wheel cylinder 2 is released to the master cylinder side, the brake is released, and the vehicle starts moving.

Next, details of the internal structure of the anchor body 7 will be explained with reference to FIG.

The sliding anchor 6 of this embodiment has a pair of shaft members 1
3a and 13b, and is slidably fitted into the center through hole 12 of the anchor body 7. The anchor body 7 is fixed to the back plate 3 with bolts 11a.

The anchor body 7 is further formed with a recess 15 parallel to the center through hole 12, into which the switch 8 is fitted, and a U-shaped stopper 19 is engaged with the groove of the switch 8 body. It is fixed to the anchor body 7 via the seal ring 17. The switch actuator 9 is biased to the left by a spring within the switch 8 body, and is slidable relative to the switch 8 body. The seal ring 17 prevents dirt and water from entering the main body of the switch 8 and adhering to the contacts within the main body. A lead wire 14 from the switch 8 is guided to the outside through a through hole 16 formed in communication with the recess 15. The inside of the through hole 16 may be filled with a mold.

The actuator 9 of the switch 8 is one shaft member 13b.
protrusion 6b (one end 26b of the sliding anchor 6)
), and in the state shown, switch 8
is off. In addition, both ends 2 of the sliding anchor 6
Rubber boots 18a, 18b are stretched between 6a, 26b and both ends of the anchor body 7 to prevent dirt and water from entering the anchor body 7.

FIG. 3 shows a modification of the internal structure of the anchor body 7 shown in FIG. 2, and parts corresponding to those in FIG. 2 are designated by the same reference numerals.

Also in this modified example, a center through hole 12 and a recess 15' parallel to the center through hole 12 are formed in the anchor body 7', and the shaft members 13a and 13b are slidably inserted into the center through hole 15'.
The switch 8' is fitted into the recess 15' and fixed to the anchor body 7' by a stopper 19, but the waterproof and dustproof structure is shown in Fig. 2. different from. That is, in this modification, a rubber cap 20 is fitted onto the actuator of the switch 8', thereby protecting the contacts within the switch 8' body from dirt and water. Furthermore, the rubber elasticity of the rubber cap 20 acts as a vibration damper, thereby preventing the switch actuator from vibrating and wearing out during running. Furthermore, both protrusions 6a and 6b of the sliding anchor 6 and the center through hole 12 of the anchor body 7'
Rubber boots 21a and 21b are stretched between both ends of the center through hole 12 to prevent water and dirt from entering the center through hole 12.

The entire brake system according to an embodiment of the present invention will be described below with reference to FIG. 4. In addition, the first
Parts corresponding to the figures are given the same reference numerals,
A detailed explanation thereof will be omitted.

In FIG. 4, a brake pedal 32 is connected to a tandem master cylinder 31, and its first hydraulic pressure generating chamber is connected to a wheel cylinder of a front wheel 34 via a pipe 33. This front wheel 34 is equipped with a disc brake. The second hydraulic pressure generating chamber is pipe line 3
5. It is connected to the wheel cylinder 2 of the rear wheel 40 via a valve device 36, a conduit 37, a solenoid valve 38, and a conduit 39, which will be described in detail later. In FIG. 4, rotation is omitted to simplify the drawing compared to FIG. 1.

In FIG. 4, the electric lines are shown by dashed lines, and the positive terminal 41 of the battery, the ignition switch 42, and the relay 43 are connected to one electric line connected to the switch 8, and to the other electric line. is connected to the solenoid 48 of the electromagnetic valve 38, the operation indicator lamp 50, the parking switch 51, the door switch 52, and the buzzer 53.

The solenoid 43a of the relay 43 has a reverse
A switch 46 and a battery positive terminal 47 are connected. The reverse switch 46 is closed when the reverse gear is switched, the solenoid 43a is energized, and the movable contact is switched to the fixed contact 44 side. When reverse switch 46 is open, the movable contact is connected to fixed contact 45 as shown.

In the state shown, the ignition switch 42 closes, and when the sliding anchor 6 moves to the right from the position shown in the drawing by the action explained in FIG. 1, the switch 8 closes.
Current flows from the positive terminal 41 of the battery to the solenoid valve 38.
The current flows to the solenoid 48 and the operation indicator lamp 50.

The solenoid valve 38 is a two-position solenoid switching valve, and when the solenoid 48 is not energized, it assumes the D position under the action of a spring 49, allowing the pipes 37 and 39 to communicate with each other, but when the solenoid 48 is energized, Position E is taken, and the pipes 37 and 39 are made non-communicating.

The parking switch 51 is closed as shown in the figure when the parking brake is not activated.
It is configured to open when activated. The door switch 52 is configured to be open as shown in the figure when the door is closed, and closed when the door is opened. Therefore, when the switch 8 provided in the rear wheel 40 is closed and the door is opened without operating the parking brake, the buzzer 53 will sound.

Next, details of the valve device 36 will be explained.

The valve body 60 has a stepped hole 61 into which a stepped piston 62 fitted with a seal ring is slidably fitted. Master cylinder pressure chambers 64, 65 are formed on both sides of the stepped piston 62, and these are always in communication with the master cylinder 31 side via through holes 68, 66 and conduits 35, 67, 33. The stepped piston 62 is biased to the left by a spring 63, and is normally in the position shown in the figure, abutting against a protrusion 60a on the left end wall.

A through hole 69 is formed in the small diameter portion of the stepped piston 62 in the radial direction, and a stepped hole 70 is further formed in the axial direction in communication with the through hole 69. A valve ball 72 is disposed in the large diameter portion of the stepped hole 70 and is biased by a spring 71, and normally the inclined stepped portion 70 is disposed as shown in the figure.
It is in contact with a. That is, the inclined stepped portion 70a functions as a valve seat. In addition, the stepped piston 6
A link-shaped rubber plate 73 is attached to the right end surface of the valve body 60, facing the inner right end wall of the valve body 60, and being concentric with a through hole 74 formed in the right end wall. When the stepped piston 62 moves to the right and the rubber plate 73 comes into contact with the wall surface 60b around the through hole 74, communication between the master cylinder pressure chamber 64 and the through hole 74 is cut off. That is, the wall surface 60b functions as a valve seat. However, the master cylinder pressure chamber 64
Pressure liquid from the stepped piston 62 can pass through the small diameter part of the stepped hole 70 in the axial direction of the through hole 69 of the stepped piston 62, open the valve ball 72, and flow into the pipe line 37 side through the through hole 74. . This reverse flow is prohibited.
That is, the valve ball 72, the spring 71, and the inclined stepped portion 70a serving as a valve seat constitute a check valve.

Although the embodiment of the present invention is configured as described above,
Next, this action, effect, etc. will be explained.

Assume that the car is currently climbing a slope and the brake pedal 32 is depressed to stop the car. In addition, in FIG. 4, the ignition switch 42
is closed, but the other switches and components are in the state shown.

Pressure fluid from the master cylinder 31 is supplied to the wheel cylinder of the front wheel 34 through the pipe line 33, and the pipe line 35, the passage 68 of the valve device 36, the master cylinder pressure chamber 64 passage hole 74, the pipe line 37, the electromagnetic valve 38
(Switch 8 remains off, so solenoid 48 is not energized and is in position D), and is supplied to wheel cylinder 2 of rear wheel 40 through line 39. In the valve device 36, the stepped piston 62 receives hydraulic pressure from the master cylinder pressure chambers 64 and 65 on both sides, but since the pressure receiving area on the one master cylinder pressure chamber 65 side is larger, it moves to the right due to this pressure receiving area difference. When the hydraulic pressure overcomes the spring force of the spring 63, the stepped piston 62 moves to the right, and the rubber plate 73 at the tip seats on the wall surface 60b serving as a valve seat. Thereafter, the pressure liquid from the master cylinder 31 passes through the master cylinder pressure chamber 64, the through hole 69, and the stepped hole 70,
The valve ball 72 is opened and supplied to the wheel cylinder 2 side of the rear wheel 40.

Brakes are applied to both wheels 34 and 40 to decelerate the vehicle. In the rear wheel 40, shoes 4a and 4b
is in pressure contact with the drum 5 (rotating in the direction of arrow R), and a frictional force is generated between the drum 5 (rotating in the direction of arrow R), but as explained in Fig. 1, the brake reaction force acting on the shoe 4a on the leading side is is large, and the sliding anchor 6 remains in the left forward movement position shown in the figure. That is, since the switch 8 remains off, the solenoid 48 of the solenoid valve 38 remains de-energized, and D
continue to take the position.

When the car stops on a slope, the drum 5, which was rotating together with the wheels, generates a rotational force in the opposite direction to that when the car was running, and the frictional force acting between the drum 5 and the shoes 4a and 4b is reduced. is reversed. As a result, the brake reaction force on the shoe 4b on the trailing side becomes larger, and the sliding anchor 6 is pushed to the right and assumes a rightward forward movement position. The actuator 9 of the switch 8 is pushed in by the protrusion 6b of the sliding anchor 6. The switch 8 is turned on, the solenoid 48 of the solenoid valve 38 is energized, and the solenoid valve 38 is switched to position E. Thus, the master cylinder 31
side and the wheel cylinder 2 side are cut off. When the driver releases the pressure on the brake pedal 32 in this state, the brake fluid flows back to the master cylinder 31 from the wheel cylinder of the front wheel 34, but since the solenoid valve 38 is in the cut-off state, the brake fluid flows back to the master cylinder 31 from the wheel cylinder of the rear wheel 40. From 2 onwards, the brake fluid does not flow back,
Pressure fluid is held here. This allows the vehicle to remain stationary on a slope. In the valve device 36, when the hydraulic pressure of the master cylinder 31 decreases to such an extent that the hydraulic pressure to the right on the stepped piston 62 becomes smaller than the spring force of the spring 63, the valve device 36 moves to the illustrated position, and the rubber plate 73 is moved to the position shown in the figure. Wall surface 60 as a valve seat
b, and the conduit 37 side and the master cylinder pressure chamber 64 are in free communication, but the solenoid valve 38
Since it is in the cutoff state, it has no relation to maintaining the braking force of the rear wheel 40. The clutch is switched to a neutral state, and in the past it was necessary to keep pressing the clutch pedal in order to maintain braking force, but in this embodiment it is possible to keep the foot off the pedal.

When the solenoid 48 of the solenoid valve 38 is energized, the operation indicator lamp 50 lights up, allowing the driver to recognize that the solenoid valve is activated and the braking force is maintained.

However, the driver ignores or forgets this and leaves the driver's seat without applying the parking brake.
Possibly getting out of the car. In this embodiment, in such a case, the buzzer 53 sounds to issue a warning to the driver. That is, the parking switch 51 remains closed, and when the door is opened, the door switch 52 is closed and the buzzer 53 is energized. When the parking brake is applied, the parking switch 51 opens, so the buzzer 53 does not sound.

In order to start the car, when you change gears, put the clutch pedal in the half-clutch state, and step on the accelerator pedal, the driving force is transmitted to the drum 5 of the rear wheel 40, and the friction between the drum 5 and the shoes 4a, 4b is reduced. The force is reversed again, and the force is on the leading side.
The brake reaction force to a becomes larger, and the sliding anchor 6 is pushed to the left and assumes the position shown in the figure.
Switch 8 is turned off, and solenoid 4 of solenoid valve 38 is turned off.
The power supply to 8 is cut off. The solenoid valve 38 takes the position D again, and the master cylinder 31 side and the wheel cylinder 2 side are brought into communication. The pressure fluid held in the wheel cylinder 2 flows back to the master cylinder 31 through the valve device 36 in the illustrated state. The brake is then released and the car starts.

Note that after stopping on a slope, you may want to actively back up. In this case, when the gear is changed to reverse, the reverse switch 46 is closed and the relay 43 is energized. As a result, the movable contact is switched to the other fixed contact 44 side. In response to this, the power supply to the switch 8 is cut off, the solenoid valve 38 takes the position D, and the pressure fluid in the wheel cylinder 2 of the rear wheel 40 flows back to the master cylinder 31 side. The car can therefore freely move backwards.

The above describes the normal case where a car stops on a slope, but depending on the slope angle of the slope and the suspension mechanism of the car body, the switch 8 of the rear wheel 40 may remain in the on state when sudden braking is applied. There may also be cases where it is not done. Valve device 36 is provided to deal with such a case.

That is, in the above case, when the brakes are applied suddenly, the car undergoes a so-called nose dive phenomenon, and the rear wheels of the car body become lifted off the ground. After that, it sinks by swinging back, and then it swings back again to nosedive. During the first nose dive, switch 8 remains off, but
It turns on when it sinks back into the swing. However,
Furthermore, the switch 8 is turned off at the next nose dive. The switch 8 does not turn on stably when the vehicle stops. In the end, the back torque of the front wheels will maintain the vehicle at a standstill (the brake pedal 32 remains depressed), so the switch 8 will not necessarily turn on after a sufficient amount of time has elapsed. Valve device 36 is provided to deal with such a situation.

That is, after sudden braking is applied, when the pressure on the brake pedal 32 is released, the pressure fluid in the wheel cylinder of the front wheel 34 begins to flow back to the master cylinder 31 through the conduit 33. However, the valve device 3
6, the stepped piston 62 is still moving to the right, and the rubber plate 73 is attached to the wall surface 60 as a valve seat.
Since the vehicle is seated at position b, there is a delay in the flow of pressure fluid from the wheel cylinder 2 of the rear wheel 40 to the master cylinder 31 side. During this delay, the proportion of back torque applied to the front wheels 34 due to the backward tendency of the wheels decreases, and that of the rear wheels 40 increases, and the switch 8 of the rear wheels 40 is turned on, which is maintained thereafter.

After the switch 8 is turned on, the hydraulic pressure to the right of the stepped piston 62 in the valve device 36 becomes smaller than the sum of the hydraulic pressure to the left and the spring force of the spring 63 as the hydraulic pressure on the pipe line 67 side decreases. start moving to the left and assume the position shown. Although the pipe line 37 side and the master cylinder pressure chamber 64 are in free communication, the solenoid valve 38 is already in the closed state, so the pressure fluid is transferred from the wheel cylinder 2 of the rear wheel 40 to the master cylinder 31.
Braking force is maintained without flowing back to the side.
Starting is performed in the same manner as described above.

The embodiments of the present invention have been described above, but of course the present invention is not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the embodiment described above, it is not possible to further increase the braking force on the rear wheels 40 when stopped on a slope, but in parallel with the solenoid valve 38, the direction from the master cylinder 31 side to the wheel cylinder 2 side is the reverse direction. By connecting a stop valve, it becomes possible to further increase the capacity.

Further, in the above embodiment, the brake is applied only to the rear wheels 40, but if the braking force is insufficient, the front wheels 34 may also be applied with the brake. In this case, as has already been proposed, a valve device that receives the brake fluid pressure of the rear wheels and closes accordingly may be provided between the master cylinder and the front wheels. As this valve device, for example, the valve device 36 shown in the embodiment can be applied as is. That is, the pipe line 35 from the master cylinder 31 is directly connected to the solenoid valve 38, and the pipe line 35 is directly connected to the solenoid valve 38.
3 is connected to the through hole 68 of the valve device 36, the through hole 74 is connected to the wheel cylinder of the front wheel 34, and the through hole 74 is connected to the wheel cylinder of the rear wheel 40.
The wheel cylinder 2 is further connected to the through hole 6 of the valve device 36.
6.

Further, a clutch switch may be used instead of the parking switch 51 in the above embodiment. In this case, it is a switch that opens when the clutch pedal is depressed.

Further, in the above embodiments, the switch 8 is accommodated within the anchor body 7, but may be attached to the outside of the anchor body 7.

〔Effect of the invention〕

As described above, according to the brake device of the present invention, it is possible to maintain a stopped state of the vehicle even if the clutch pedal is not continuously depressed, and even if members such as the clutch plate are worn out, it is possible to maintain the stopped state of the vehicle etc. While achieving the effect that there is no timing difference between the timing and the actual movement of the wheels or the vehicle body, erroneous operation of the switch is reliably prevented, and there is almost no need to increase the force applied to the brake pedal.

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a wheel on a slope for explaining the operating principle and basic configuration of the present invention; Fig. 2 is an enlarged sectional view showing details of the internal structure of the anchor body in Fig. 1; 3 is an enlarged sectional view showing a modification of FIG. 2, and FIG. 4 is a piping system diagram showing the entire brake device according to an embodiment of the present invention. In the figure, 1...wheels, 4a, 4b...
Show, 5...Drum, 6...Sliding anchor, 8
...Switch, 10a, 10b, 10c...Return spring, 38...Solenoid valve.

Claims (1)

[Claims] 1. Normally, there is a cylinder between the wheel cylinder, which can press one end of a pair of LT drum brakes toward the drum against the biasing force of a return spring, and the master cylinder, which generates hydraulic pressure when operated by the driver. A solenoid valve is provided that is in a communication position and can be switched to a cutoff position in response to a command, and a sliding anchor, which the other ends of the pair of shoes abut, is movable within a predetermined range, and the connection between the drum and the pair of shoes is In a brake device equipped with a switch that detects displacement of the sliding anchor due to a change in the direction of action of a frictional force acting therebetween and issues a command to the electromagnetic valve,
The other end portions of the pair of shoes are biased toward the sliding anchor by separate return springs, and the shoe is provided for one of the pair of shoes that becomes a leading shoe when moving forward. A brake device in which the biasing force of a return spring is greater than the biasing force of a return spring provided for the other shoe.