JP2003156080A - Vehicular drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular drum brake device allowing the output shaft of an actuator to be reset to an initial position by the energizing force of a return spring, minimizing an increase in weight of the whole device due to the greater energizing force of the return spring and surely preventing the entry of foreign matters into the actuator. SOLUTION: The actuator 20 has a second return spring 29 in a coiled form inserted through the output shaft 21 for compressing the output shaft 21, when linearly moved to a set-in direction, to energize the output shaft 21 to be reset to the initial position. The outside of the second return spring 29 is provided with a waterproof boot 28 consisting of an approximately cylindrical elastic member for preventing the entry of foreign matters from a gap between the output shaft 21 and a housing 24 of the actuator 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle drum brake device using an electric actuator as a drive source.

[0002]

2. Description of the Related Art Recently, in a vehicle drum brake device,
For example, as disclosed in Japanese Examined Patent Publication No. 6-100239, there has been proposed one configured to operate with a brake actuator using an electric motor as a drive source.

In the above-mentioned drum brake device, the bottomed cylindrical drum is fixed to the axle so as to rotate integrally therewith, and the back plate is non-rotatably disposed on the opening side of the drum. A pair of brake shoes are supported on the back plate so that they can come into contact with and separate from the inner peripheral surface of the drum. The brake shoe is biased by a return spring (in the publication, a return spring) in a direction away from the inner peripheral surface of the drum, and is held in a state of being slightly separated from the inner peripheral surface.

Further, the brake shoe is brought into contact with and separated from the inner peripheral surface of the drum by the operation of a swingably provided lever. The lever is swung by the retracting movement (reciprocating linear movement) of the output shaft of the actuator using the electric motor as a drive source. This actuator is configured such that when the motor rotates in the forward direction, the output shaft is retracted from the initial position, and when the motor rotates in the reverse direction, the output shaft projects to the initial position. When the output shaft of the actuator retracts, the lever presses the brake shoe against the inner peripheral surface of the drum, and when the output shaft protrudes, the lever operates so as to separate the brake shoe from the inner peripheral surface of the drum. Such a lever increases the driving force of the actuator by the lever action, and the increased driving force presses the brake shoe against the inner peripheral surface of the drum to obtain a large braking force.

[0005]

In the drum brake device having the above structure, when the brake shoe is separated from the drum, the urging force of the return spring mainly acts in the direction in which the output shaft of the actuator is projected via the lever. is doing. Therefore, when separating the brake shoe from the drum, without rotating the motor in reverse,
It is considered that by increasing the biasing force of the return spring, the output shaft of the actuator is returned (projected) to the initial position only by the biasing force of the spring. This is because it is not necessary to control the motor to rotate in the reverse direction, so that the configuration of the controller that controls the motor can be simplified.

However, since the return spring is located on the action point side of the lever utilizing the lever action, unless the urging force of the return spring is excessively increased, only the urging force of the return spring is used to output the actuator output shaft. Cannot be returned to the initial position. Therefore, the return spring is excessively increased in size in order to excessively increase the biasing force of the return spring. Further, it is necessary to increase the rigidity of the member on which the biasing force of the return spring acts, and it is necessary to increase the size of the member. As a result, there is a problem that the weight of the entire drum brake device is significantly increased.

Further, since the brake device is attached to a place where foreign matter such as rainwater and dust adheres, the actuator used in the device needs to be securely sealed so that the foreign matter does not enter inside. In particular, the output shaft of the actuator has a clearance between the output shaft and the housing in order to move in and out (reciprocating linear motion). Therefore, it is ensured that foreign matter does not enter the inside through the gap between the output shaft and the housing. It is required to keep it sealed.

The present invention has been made to solve the above problems, and an object thereof is to revise the output shaft of the actuator to the initial position side by the urging force of the return spring. A drum brake device for a vehicle, which is capable of suppressing an increase in the weight of the entire device by strengthening the biasing force of the return spring and reliably preventing foreign matter from entering the actuator. To do.

[0009]

In order to solve the above problems, the invention according to claim 1 provides a substantially cylindrical drum having a bottom which rotates together with an axle, and a non-rotatable arrangement on the opening side of the drum. A back plate provided, a brake shoe supported by the back plate and arranged so as to be able to come into contact with and separate from the inner peripheral surface of the drum, and urge the brake shoe in a direction to separate from the inner peripheral surface of the drum. A return spring for swinging, an operating lever having one end drivingly connected to the brake shoe so as to bring the brake shoe into and out of contact with the inner peripheral surface of the drum by the swing, and the operating lever. Has an output shaft drivingly connected to the other end of the return spring, and the output shaft linearly moves from the initial position in the retracting direction to move the actuating lever to one side. A drum brake device for a vehicle, comprising: an electric actuator that presses the brake shoe against an inner peripheral surface of the drum against a force, wherein the actuator is coiled and inserted into the output shaft. A second return spring is provided that compresses the output shaft when it linearly moves in the retracted direction and urges the output shaft to return to the initial position. Outside the second return spring, the second return spring and the output shaft and the output shaft are provided. There is provided a waterproof boot made of a substantially tubular elastic member that prevents foreign matter from entering through a gap between the actuator and the housing.

According to a second aspect of the present invention, in the vehicle drum brake device according to the first aspect, the waterproof boot is attached to the waterproof boot when the second return spring is compressed and deformed and is bent outward in the radial direction. The dimensions of the second return spring or the waterproof boot are set so as not to come into contact with each other.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the vehicle drum brake device described in the paragraph [4], the waterproof boot is formed in a spiral outer shape so as to be synchronized with the second return spring.

According to a fourth aspect of the present invention, in the vehicle electric brake device according to any one of the first to third aspects, the second return spring is provided when the output shaft moves in the retracted direction. The twisting direction of the spring is set so as to extend when one end is twisted by a slight rotation.

(Operation) According to the invention described in claim 1,
The actuator is provided with a second return spring which is inserted in the output shaft in a coil shape and which compresses when the output shaft linearly moves in the retracted direction and urges the output shaft to return to the initial position. Therefore, the output shaft of the actuator will return to the initial position side in cooperation with the return spring that biases the brake shoe in the direction away from the inner peripheral surface of the drum and the second return spring provided inside the actuator. And In this case, the second return spring is located on the force point side of the actuating lever utilizing the lever action, so that the second return spring can be small. As a result, it is not necessary to excessively increase the rigidity of the member on which the second return spring acts, so that the increase in size of the member can be suppressed as much as possible. Therefore, the weight of the entire brake device increases by the amount of the second return spring, but the increase can be suppressed as much as possible. Further, a waterproof boot made of a substantially tubular elastic member is provided outside the second return spring, and the waterproof boot can prevent foreign matter from entering through a gap between the output shaft and the actuator housing. . Further, in this case, since the foreign matter is prevented from adhering to the second return spring by the waterproof boot, it is possible to prevent the spring from being unable to be sufficiently compressed due to the foreign matter adhering to the spring.

According to the second aspect of the present invention, the dimensions of the second return spring or the waterproof boot are set so that the second return spring does not come into contact with the waterproof boot when the second return spring bends outward in the radial direction when compressed and deformed. Is set. Therefore, since the second return spring does not come into contact with the waterproof boot when the second return spring is compressed and bent outward in the radial direction, for example,
It is possible to prevent the waterproof boot from being sandwiched between the compressed second return springs, and to prevent damage to the waterproof boot due to this.

According to the third aspect of the invention, the waterproof boot is formed in a spiral shape so as to be synchronized with the second return spring. Therefore, the waterproof boot and the second return spring are similarly compressed and deformed. Therefore, for example, it is possible to prevent the waterproof boot from being sandwiched between the compressed second return springs, and to prevent damage to the waterproof boot due to this.

According to the fourth aspect of the invention, the second return spring slightly rotates when the output shaft moves in the retracted direction and expands when one end is twisted. Therefore, the biasing force of the spring can be sufficiently exerted.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a vehicle drum brake device 1. The bottomed cylindrical drum 2 is fixed to an axle (not shown) so as to rotate integrally, and a disc-shaped back plate 3 is non-rotatably disposed on the opening side of the drum 2. A pair of brake shoes 4 and 5 are arranged in the space inside the drum 2. Brake shoes 4, 5
Each have an arc shape, and the inner peripheral surface 2a of the drum 2
It is supported by the back plate 3 so that it can come into contact with and separate from.

One end of each of the brake shoes 4 and 5 is connected to each other via an adjuster 6, and the other end is fixed to the outer peripheral edge of the back plate 3 via return springs 7 and 8, respectively. It is connected to 9. Then, the other ends of the brake shoes 4, 5 both come into contact with the fixed pin 9 by the urging force of the return springs 7, 8, and the brake shoes 4, 5 are held at this position. At this time, the brake shoes 4 and 5 are held in a state of being slightly separated from the inner peripheral surface 2a of the drum 2.

One end (which serves as a fulcrum and an action point) of the operating lever 10 is connected to the fixed pin 9 side of one brake shoe 4 by a connecting pin 11. This operating lever 1
An end portion 12a of the connecting bar 12 is connected to a portion of 0 which is close to the fixing pin 9 (which serves as a fulcrum and an action point). The other end 12b of the connecting bar 12 has the other brake shoe 5
Is connected to a portion near the fixing pin 9.

The other end of the actuating lever 10 (which is the power point)
Is connected to an output shaft 21 operated by the brake actuator 20. Brake actuator 20
Are fixed to the back plate 3 at a plurality of locations (only three locations are shown in FIG. 1) by mounting bolts 13.
The position of the output shaft 21 shown in FIG. 1 is the most projecting position (initial position) and is the position that is arranged when the brake operation is not performed.

When the brake operation is performed, the brake actuator 20 is actuated, and the output shaft 21 is retracted from the initial position (moved to the right in FIG. 1). Then, the operating lever 10 rotates in the clockwise direction in FIG.
The actuating lever 10 rotates in the same direction with the end 12a of the as a fulcrum. Therefore, the fixed pin 9 side of each brake shoe 4, 5 is expanded against the biasing force of the return springs 7, 8. The brake shoes 4, 5 are the drum 2
When it contacts the inner peripheral surface 2a, a frictional force is generated between the brake shoes 4, 5 and the drum 2, and a braking force is generated.

Such a brake actuator 20
As shown in FIG. 2, the drive motor 22 includes a drive motor 22 and a brake drive unit 23 that reduces the rotation of the drive motor 22 and converts the reduced rotational movement into a linear movement of the output shaft 21.

Specifically, the drive motor 22 is integrally assembled to the housing 24 of the brake drive unit 23, and the housing 24 and the drive motor 22 are fixed to the back plate 3 by the mounting bolts 13. A pinion 25 is provided on the rotary shaft 22a of the drive motor 22 so as to rotate integrally therewith. The pinion 25 is meshed with the first reduction gear 26, and the first reduction gear 26 is meshed with the second reduction gear 27. The second reduction gear 27 has an output shaft portion 27a having a screw hole (not shown) formed in the axial direction.

On the other hand, the output shaft 21 is non-rotatably and axially movably supported by a second return spring 29 mounted between hooking portions 21x and 24x described later. The output shaft 21 has a connecting portion 21a connected to the actuating lever 10 at the tip portion and a worm portion 21b at the base end portion. The worm portion 21b is screwed with the output shaft portion 27a. It should be noted that, between the output shaft 21 and the opening of the housing 24, a waterproof member is formed of a substantially bellows-like elastic member that prevents foreign matter such as rainwater and dust from entering through a gap between the output shaft 21 and the opening. Boots 28 are attached. The waterproof boot 28 is formed in a substantially bellows shape so that it can easily follow the operation of the output shaft 21.

Inside the waterproof boot 28, a coiled second return spring 29 is mounted in a state of being inserted into the output shaft 21. That is, by inserting the second return spring 29 into the output shaft 21, the arrangement space of the spring 29 is reduced and the actuator 2
0 size reduction can be suppressed. Second return spring 29
Is a hook portion 21x provided on the output shaft 21 and a housing 24.
It is interposed between the hooking portion 24x provided on the. In this case, the two hooks 21x and 24x have grooves, protrusions, etc. with which the ends of the second return spring 29 engage, and the spring 2
9 is fixed non-rotatably. Therefore, the output shaft 21
Will be non-rotatably supported with respect to the housing 24. Therefore, a rotation stopping mechanism for making the output shaft 21 non-rotatable is not required, so that the structure can be simplified, and the cost can be reduced and the reliability can be improved by reducing the number of parts.

The second return spring 29 as described above urges the output shaft 21 in the direction in which the output shaft 21 is projected by its urging force. Therefore, when the output shaft 21 is retracted by driving the drive motor 22, the second return spring 2
The output shaft 21 is retracted by compressing 9 (against the biasing force).

In this case, as shown in FIG. 7, the second return spring 29 or the waterproof boot 29 is prevented from coming into contact with the waterproof boot 28 when the second return spring 29 is compressed and deformed and is bent outward in the radial direction. 28 dimensions are set. Therefore, since the second return spring 29 does not contact the waterproof boot 28 when the second return spring 29 is compressed and deformed outward in the radial direction, damage to the waterproof boot 28 due to, for example, sandwiching the waterproof boot 28 between the compressed springs 29. It is prevented.

As shown in FIGS. 2 and 3, in the housing 24, the pinion 25 is switched from a rotatable state to a non-rotatable state so that the load side (operating lever 10
A slip prevention mechanism 30 is provided to prevent the output shaft portion 27a from slipping due to an external force input from the side).

More specifically, the idling prevention mechanism 30 comprises a switching motor 31 and a restriction gear 32. Switching motor 3
1 is assembled in the housing 24, and the motor 31
A pinion 31a is provided on the rotation shaft of so as to rotate integrally. The restriction gear 32 is rotatable by a shaft 26 a that supports the first reduction gear 26, and is supported so as not to rotate integrally with the first reduction gear 26.

As shown in FIG. 3, the restriction gear 32 has a first meshing portion 32a for meshing with the pinion 31a of the switching motor 31 and a second meshing portion for meshing with the pinion 25 of the drive motor 22. 32b. The second meshing portion 32b projects outward from the first meshing portion 32a in a fan shape. The restriction gear 32 is rotated by the operation of the switching motor 31, and each of the rotation directions of the second meshing portion 32b that is fan-shaped and protrudes with respect to the first and second restriction walls 24a and 24b formed in the housing 24. The contact between the end surfaces 32c and 32d restricts the rotation at a predetermined angle. The regulation gear 32 is regulated by the first regulation wall 24a and meshed with the pinion 25 of the drive motor 22 (see FIG. 5), and the second regulation wall 24b regulates the pinion 25. It is arranged so as to be switched to a non-meshing position (see FIG. 4) where it does not mesh.

That is, when the restriction gear 32 is arranged at the non-meshing position shown in FIG. 4, the rotation of the pinion 25 is allowed. On the other hand, when the restriction gear 32 is arranged at the meshing position shown in FIG. 5 and a rotational force acts on the pinion 25 in the counterclockwise direction (the direction of arrow B), the end surface 32c of the second meshing portion 32b has the first restriction wall 24a. Abutting against the control gear 32,
Rotation in the clockwise direction is prevented. That is, in this state, the rotation of the pinion 25 in the arrow B direction is prohibited.

An engagement hole 32e is formed in the side surface of the first meshing portion 32a of the regulation gear 32. In contrast,
An engagement pin 33 that engages with an engagement hole 32e of the gear 32 when the restriction gear 32 is disposed at the non-meshing position shown in FIG. 4 is provided in the housing recess 24c formed in the housing 24.
Are movably provided in the axial direction. This engagement pin 3
3 is constantly urged toward the regulation gear 32 side by the urging force of the spring 34. That is, when the restriction gear 32 is arranged at the non-meshing position shown in FIG. 4, the engagement hole 32e and the engagement pin 33 engage with each other and are held at that position. This prevents the restriction gear 32 from unexpectedly rotating due to vibration or the like and interfering with the pinion 25.

A hexagonal tool connection hole 32f into which a tool (not shown) such as a hexagon wrench is fitted is formed on the side of the restriction gear 32 opposite to the reduction gear 26. Corresponding to this, FIG.
As shown in FIG. 3, the housing 24 has an insertion hole 24 that communicates with the restriction gear 32 (tool connection hole 32f) from the outside.
d is formed. The insertion hole 24d is a screw hole into which the closing bolt 35 is screwed. This closing bolt 35
Has its tip substantially contacting the regulation gear 32,
It is designed to receive the load in the thrust direction.

FIG. 6 shows an electrical structure for driving the brake device 1. The brake device 1 (the drive motor 22 and the switching motor 31) is controlled by a brake controller 40 mounted on the vehicle. The controller 40 of the present embodiment drives the drive motor 22 only in one direction (direction of arrow A in FIGS. 2, 4, and 5). The controller 40 receives power supply from the battery 41 of the vehicle.

An operation amount detecting device 42 for detecting an operation amount (for example, at least one of a stroke amount and an operating force) of a driver's brake operation member (pedal, lever, switch) is connected to the controller 40, and the device is connected to the operation amount detecting device 42. An operation amount detection signal corresponding to the operation amount is input from 42.

A parking brake operation switch 43 is connected to the controller 40. The parking brake operation switch 43 outputs an on / off signal based on an operation of a parking brake operation lever (not shown) mounted on the vehicle, and outputs the on / off signal to the controller 40. That is, when the parking brake operation lever is operated to the parking position, the parking brake operation switch 43 outputs an ON signal (parking signal) to the controller 40. When the parking brake operation lever is operated to the parking release position, the parking brake operation switch 43 turns off (parking release signal).
Is output to the controller 40.

Then, the controller 40 enters the "normal brake mode" or the "parking brake mode" based on the ON / OFF signal from the parking brake operation switch 43. That is, the controller 40 enters the "parking brake mode" when the parking brake operation switch 43 outputs the ON signal (parking signal), and when the parking brake operation switch 43 outputs the OFF signal (parking release signal). The "normal brake mode" is set.

[Normal Brake Mode] This mode is a mode executed when the vehicle is running and when the vehicle is stopped. In this mode, the controller 40 controls the switching motor 31 to dispose the restriction gear 32 in the non-meshing position shown in FIG. 4, and brings the drive motor 22 into a rotation-free state.
In this case, since the engagement hole 32e of the regulation gear 32 and the engagement pin 33 are engaged with each other and the regulation gear 32 is maintained at that position, the controller 40 stops the power supply to the switching motor 31. is doing.

Then, when the brake operation amount increases, the controller 40 supplies a drive power source corresponding to the brake operation amount to the drive motor 22 to rotate the motor 22 in the direction of arrow A, and to rotate the pinion 25 and the gears 26, 27. The output shaft portion 27a is rotated through the above so that the output shaft 21 is retracted against the urging force of the second return spring 29. Then, the brake shoes 4, 5 are expanded by the actuating lever 10 against the urging force of the return springs 7, 8, and the brake shoes 4, 5 are pressed against the inner peripheral surface 2 a of the drum 2. That is, the braking force of the brake device 1 increases.

On the other hand, when the brake operation amount decreases, the controller 40 decreases the drive power supply to the drive motor or stops the supply of the drive power supply according to the brake operation amount. In this case, the output shaft 21 projects while the drive motor 22 rotates in the direction of arrow B due to the urging force of the second return spring 29 and the return springs 7 and 8, and the brake shoes 4 and 5 are attached to the inner peripheral surface 2a of the drum 2. Move in a direction away from. That is, the braking force of the brake device 1 is reduced.

As described above, the controller 40 controls the drive motor 2 based on the operation amount detection signal corresponding to the brake operation amount.
2 to control the brake shoes 4, 5 for the drum 2.
The brake force of the brake device 1 is controlled by changing the pressure contact force of the brake shoes 4 and 5 with respect to the drum 2 while contacting and separating.

[Parking Brake Mode] This mode is a mode executed when the vehicle is parked. In this mode, the controller 40 operates the parking brake operation switch 4
Based on the ON signal (parking signal) of No. 3, first, the drive motor 22 is driven until the pressure contact force (braking force) of the brake shoes 4, 5 with respect to the drum 2 is equal to or greater than a predetermined value, that is, the braking force required for parking the vehicle is obtained. Power is supplied to drive the motor 22 with arrow A.
The output shaft 21 is immersed.

Next, the controller 40 controls the switching motor 31 to rotate the restriction gear 32 in the clockwise direction in FIG. 4, and the restriction gear 32 shown in FIG.
It is placed at the meshing position where it meshes with. At this time, the controller 40 stops the power supply to the drive motor 22 at the same time when the restriction gear 32 meshes with the pinion 25. Then, in addition to the urging force of the return springs 7 and 8, the urging force of the second return spring 29 mainly (directly) acts in the protruding direction of the output shaft 21 (leftward in FIG. 1), and the output shaft portion 27a. , The motor 22 via the gears 27, 26
(Pinion 25) rotates in the direction of arrow B. Then, the end surface 32c of the second meshing portion 32b of the regulation gear 32 comes into contact with the first regulation wall 24a.

Then, the motor 22 (pinion 25) is in a state in which the rotation in the direction of arrow B is prohibited (locked state), so that the output shaft 21 does not move in the protruding direction (leftward in FIG. 1). The braking device 1 is maintained while generating the braking force required for parking.

In this case, the motor 22 (pinion 2
Since the rotational force in the direction of arrow B always acts on 5), the rotational force always acts on the restriction gear 32 in the direction in which the end surface 32c of the second meshing portion 32b presses the first restriction wall 24a. . Therefore, even if the power supply to the switching motor 31 is stopped, the restriction gear 32 is maintained in the meshing position and the pinion 25
Since there is no disengagement with the controller 40
Stops the power supply to the switching motor 31. Further, in this case, due to the urging force of the second return spring 29,
The restriction gear 32 and the pinion 25 can easily mesh with each other.

Then, the parking brake operating switch 4
When the off signal (parking release signal) is output from 3, the controller 40 first rotates the drive motor 22 in the direction in which the pressure contact force of the brake shoes 4 and 5 is increased, that is, the direction of arrow A, and the output shaft 21 is retracted. . Also, the controller 40
Controls the switching motor 31 to arrange the restriction gear 32 at a non-meshing position where the meshing with the pinion 25 is disengaged (FIG. 4).
The power supply to the switching motor 31 is stopped. Regulating gear 3
In No. 2, the engagement hole 32e and the engagement pin 33 engage with each other to maintain the position 2. Then, the controller 40 stops the supply of drive power to the drive motor 22 unless the brake is operated. Then, the second return spring 2
The output shaft 21 returns (projects) to the initial position while the drive motor 22 rotates in the direction of arrow B by the urging force of 9 and the return springs 7 and 8, and the brake shoes 4 and 5 are separated from the brake drum 2. In this way, the brake device 1 returns to the state in which the normal brake operation as described above is possible.

If the drive motor 22 and the switching motor 31 fail in the state where the parking brake is applied, or the power supply to the motors 22 and 31 cannot be supplied due to the rise of the battery 41, the motors 22 and 31 do not operate. In this case, in this embodiment, it is possible to manually cancel. Specifically, the closing bolt 35 shown in FIG. 2 is removed, and a tool (not shown) such as a hexagon wrench is inserted into the insertion hole 24d from which the closing bolt 35 is removed, and the tool is connected to the tool connecting hole 32f of the regulation gear 32. To fit. Then, the tool rotates the restriction gear 32 from the meshing position to the non-meshing position.
Then, the drive motor 22 (pinion 25) is in a rotation-free state, so that the output shaft 21 projects due to the urging force of the return springs 7 and 8 and the urging force of the second return spring 29, and the brake shoes 4 and 5 drum. 2, the parking brake is released.

As described above, the braking device 1 of this embodiment has the following features. (1) The actuator 20 of this embodiment includes the output shaft 2
A second return spring 29 is provided which urges the output shaft 21 to return to the initial position by compressing when 1 linearly moves in the retracted direction. Therefore, the output shaft 21 of the actuator 20 includes return springs 7 and 8 for urging the brake shoes 4 and 5 in a direction of separating the brake shoes 4 and 5 from the inner peripheral surface 2a of the drum 2, and a second return spring provided inside the actuator 20. 29 collaborates with each other to return to the initial position side. In this case, the second return spring 29
Is located on the power point side of the operating lever 10 that uses the leverage, so that it can be small. Further, as a result, it is not necessary to excessively increase the rigidity of the member on which the second return spring 29 acts (for example, the output shaft 21, the gears 26 and 27, the housing 24, etc.), so that it is possible to enlarge the member as much as possible. It can be suppressed. Therefore, the weight of the entire brake device 1 increases by the amount of the second return spring 29, but the increase can be suppressed as much as possible.

(2) In this embodiment, the coil-shaped second return spring 29 is inserted through the output shaft 21.
Therefore, the space for disposing the second return spring 29 can be reduced, and the actuator 20 can be prevented from increasing in size.

(3) In this embodiment, the output shaft 21 and the housing 2 are provided outside the second return spring 29.
The waterproof boot 28 is provided to prevent foreign matter from entering through a gap between the waterproof boot 28 and the waterproof boot 28. Therefore, the waterproof boot 28 can prevent foreign matter from entering through the gap between the output shaft 21 and the housing 24. Further, in this case, the waterproof boot 28 prevents foreign matter from adhering to the second return spring 29, and therefore prevents the spring 29 from being unable to be sufficiently compressed due to foreign matter adhering to the spring 29. You can

(4) In the present embodiment, the second return spring 29 or the waterproof boot 28 is prevented from coming into contact with the waterproof boot 28 when the second return spring 29 is compressed and deformed and is bent outward in the radial direction. The dimensions are set. Therefore, since the second return spring 29 does not come into contact with the waterproof boot 28 when the second return spring 29 is compressed and deformed outward in the radial direction, it is possible to prevent the waterproof boot 28 from being sandwiched between the compressed second return springs 29, for example. Therefore, it is possible to prevent the waterproof boot 28 from being damaged.

The embodiment of the present invention may be modified as follows. In the above-described embodiment, the substantially bellows-shaped waterproof boot 28 is used, but the shape is not limited to this, and it may be a substantially cylindrical shape. Further, for example, the waterproof boot 28a having the shape shown in FIG. 8 may be used.

As shown in FIG. 8, the waterproof boot 28a is
The outer shape thereof is formed in a spiral shape so as to be synchronized with the second return spring 29. Therefore, the waterproof boot 28a and the second return spring 29 are similarly compressed and deformed. Therefore, for example, it is possible to prevent the waterproof boot 28a from being sandwiched between the compressed second return springs 29, and to prevent the waterproof boot 28a from being damaged by this.

Further, the output shaft 21 has hook portions 21x and 24x.
Since the second return spring 29 installed in between prevents the output shaft 21 from rotating, the output shaft 21 may slightly rotate when the output shaft 21 is retracted. That is, when the output shaft 21 moves in the retracted direction, the gear 27 (output shaft portion 27a) rotates in the direction of arrow A, so the output shaft 21 rotates slightly in the same direction. Then, one end of the second return spring 29, which comes into contact with the hooking portion 21x of the output shaft 21, rotates in the same direction, and the spring 29 is twisted in the same direction. If the spring 29 is stretched when such a twist occurs, the spring 29 shown in FIG.
Alternatively, the twisting direction of the spring 29 may be set. By doing so, the second return spring 29 expands when the output shaft 21 slightly rotates in the direction of the arrow A when the output shaft 21 moves in the retracting direction.
It is possible to fully exert the biasing force of 9.

In addition to the above, the configurations of the actuator 20 and the brake device 1 may be changed appropriately. The technical ideas that can be understood from each of the above embodiments will be described below.

(A) In the electric brake device for a vehicle according to claim 1 or 2, the waterproof boot is formed in a substantially bellows shape so as to follow the operation of the output shaft. Drum brake device.

(B) In the electric brake device for a vehicle according to any one of claims 1 to 4, the electric actuator includes a drive motor as a drive source, and rotational movement of the drive motor is applied to the output shaft. A drum brake device for a vehicle, which is configured to be converted into a linear motion.

(C) In the vehicle electric brake device described in (b) above, the electric actuator includes a reduction mechanism having a plurality of gears for reducing the rotation of the drive motor, and a non-engagement mechanism that does not engage with the gears. Any one of an engagement position and an engagement position that cannot rotate even when an urging force of the second return spring that urges the output shaft to return to the initial position while engaging with the gear is applied. And a switching motor that rotates the restriction unit to switch between the engagement position and the disengagement position. .

(D) In the vehicle electric brake device described in (c) above, the drive motor is driven so that the brake shoe comes into pressure contact with the inner peripheral surface of the drum, and when a desired braking force is generated, The switching motor is driven to engage the restricting means with the gear forming the speed reduction mechanism, and at the same time when the gear and the restricting means engage with each other, the power supply to the drive motor is stopped, and the urging force of the second return spring is applied. The vehicle drum brake device is characterized in that the restriction means is maintained at the engagement position by the above.

[0060]

As described in detail above, according to the present invention,
A drum brake device for a vehicle, in which an output shaft of an actuator is returned to an initial position side by a biasing force of a return spring, and an increase in weight of the entire device by suppressing the biasing force of the return spring is suppressed as much as possible. It is possible to provide a vehicle drum brake device that can reliably prevent foreign matter from entering the inside of the actuator.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a drum brake device of the present embodiment.

2 is a sectional view taken along line XX of FIG.

FIG. 3 is a perspective view showing a main part of an actuator.

FIG. 4 is a sectional view taken along line YY of FIG. 2 for explaining the operation of the idling prevention mechanism.

5 is a sectional view taken along line YY of FIG. 2 for explaining the operation of the idling prevention mechanism.

FIG. 6 is an electrical configuration diagram of a brake device.

FIG. 7 is a sectional view showing a state in which the output shaft is immersed.

FIG. 8 is a sectional view showing an output shaft portion of another example.

[Explanation of symbols]

2 ... drum, 2a ... inner peripheral surface, 3 ... back plate, 4,
5 ... Brake shoes, 7, 8 ... Return spring, 1
0 ... Operating lever, 20 ... Brake actuator as an electric actuator, 21 ... Output shaft, 24 ... Housing, 28, 28a ... Waterproof boot, 29 ... Second return spring.

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Claims (4)

[Claims] 1. A drum having a substantially bottomed cylindrical shape that rotates together with an axle, a back plate non-rotatably disposed on the opening side of the drum, and an inner peripheral surface of the drum supported by the back plate. A brake shoe that is arranged so that it can come into contact with and separate from the brake shoe, a return spring that biases the brake shoe in a direction that separates the brake shoe from the inner peripheral surface of the drum, and the swing shoe is provided so as to swing the brake shoe. It has an actuating lever, one end of which is drivingly connected to the brake shoe, and an output shaft, which is drivingly connected to the other end of the operating lever so as to be brought into contact with and separated from the inner peripheral surface of the drum. The actuating lever is moved in one direction by linearly moving in the direction, and the brake shoe is pressed against the inner peripheral surface of the drum against the biasing force of the return spring. A vehicle drum brake device including an electric actuator, wherein the actuator has a coil shape and is inserted into the output shaft, and when the output shaft linearly moves in the retracted direction, the output shaft is compressed to initialize the output shaft. Second urge to return to position
A return spring is provided, and a waterproof boot made of a substantially tubular elastic member that prevents foreign matter from entering through a gap between the output shaft and the actuator housing is provided outside the second return spring. A drum brake device for a vehicle, which is characterized in that 2. The vehicle drum brake device according to claim 1, wherein when the second return spring is compressed and deformed, the second return spring does not come into contact with the waterproof boot when the second return spring bends outward in the radial direction. A size of the return spring or the waterproof boot is set, and a drum brake device for a vehicle. 3. The vehicle drum brake device according to claim 1, wherein the waterproof boot has a spiral outer shape so as to synchronize with the second return spring. Vehicle drum brake device. 4. The electric brake device for a vehicle according to claim 1, wherein the second return spring is slightly rotated when the output shaft moves in the retracted direction, and one end thereof is twisted. A drum brake device for a vehicle, wherein a twisting direction of the spring is set so that the spring extends when the drum brake device extends.