JP7399002B2 - Electric parking brake device - Google Patents

Description

The present invention relates to an electric parking brake device, and more particularly to an electric parking brake device including an automatic braking gap adjustment mechanism and an electric parking brake mechanism.

Conventionally, there have been electric parking brake devices equipped with an electric parking brake mechanism that operates an extension mechanism disposed between a first piston and a second piston in a foil cylinder using an electric actuator to bring the vehicle into a parking state. (For example, see Patent Document 1.) In addition, when the braking gap between the lining and the brake drum becomes wider than the appropriate range due to wear of the lining of the brake shoe between the first piston and the second piston in the wheel cylinder, Some vehicles were equipped with an automatic brake gap adjustment mechanism that automatically adjusts the brake gap (for example, see Patent Document 2).

Patent No. 6254697 Special Publication No. 1-51703

However, in the above-mentioned patent document 1, although an electric parking brake mechanism using a wheel cylinder is provided, an automatic braking gap adjustment mechanism is not provided. Furthermore, although the vehicle in Patent Document 2 is equipped with an automatic braking gap adjustment mechanism using a wheel cylinder, it is not equipped with an electric parking brake mechanism.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electric parking brake device including an automatic braking gap adjustment mechanism using a foil cylinder and an electric parking brake mechanism.

In order to achieve the above object, the electric parking brake device of the present invention is provided with a first brake shoe and a second brake shoe that are arranged in an expandable manner inside a back plate that is fixed to a vehicle body so as to be in sliding contact with a brake drum. between one end of the first brake shoe and the second brake shoe, a foil cylinder comprising a first piston that abuts the first brake shoe and a second piston that abuts the second brake shoe; An anchor member serving as an expansion center is disposed between the other end portions, and the first brake shoe and the second brake shoe are arranged in a diameter-reducing direction between the first brake shoe and the second brake shoe. a braking gap automatic adjustment mechanism that includes a return spring for urging, and adjusts a braking gap between the brake drum and the first brake shoe and between the brake drum and the second brake shoe; and an electric parking mechanism. In the electric parking brake device including an electric parking brake mechanism that brings the brake into a braking state, the braking gap automatic adjustment mechanism connects the first piston and the first piston with one end exposed to the outside from the cylinder body of the foil cylinder. 2 piston to adjust the distance in the cylinder axial direction between the first piston and the second piston, and bring the second piston into contact with the one end, and the one end An electric actuator of an electric parking brake mechanism is connected to the electric parking brake mechanism, and the electric actuator is driven to operate the second piston to enter the parking state.

The first piston may include a first clutch surface at an inner end of the cylinder body, and the braking gap automatic adjustment mechanism may include a clutch portion including a second clutch surface that abuts the first clutch surface. and a threaded portion formed on the side opposite to the second clutch surface of the clutch portion; It is preferable that the adjusting member abuts on the second piston via a bearing, and that a hydraulic pressure chamber is defined between the first piston and the clutch portion to generate hydraulic pressure when hydraulic pressure is activated. .

Further, it is preferable that the electric actuator includes a motor and a reduction gear rotated by the motor, and a gear portion that meshes with the reduction gear is formed on the outer periphery of the one end of the adjustment member.

According to the electric parking brake device of the present invention, the electric parking brake mechanism is configured by using the braking gap automatic adjustment mechanism that is arranged between the first piston and the second piston and adjusts the distance in the cylinder axial direction. Therefore, the braking gap automatic adjustment mechanism and the electric parking brake mechanism can be configured with a small number of parts. In addition, when the hydraulic brake state is released and the brake state is changed to the electric parking brake state, the parking brake force is generated by the operation of the same piston used for the hydraulic pressure operation. Parking brake force can be generated smoothly.

Furthermore, the parts that make up the automatic braking gap adjustment mechanism and the electric parking brake mechanism are integrated within the cylinder body of the wheel cylinder and around the cylinder body, allowing the automatic braking gap adjustment mechanism and the electric parking brake mechanism to be integrated in a small space. Since it is possible to provide this, layout efficiency can be improved.

Further, the first piston is provided with a first clutch surface at an end on the inside side of the wheel cylinder, and the braking gap automatic adjustment mechanism includes a clutch portion provided with a second clutch surface that contacts the first clutch surface, and a clutch portion provided with a second clutch surface that contacts the first clutch surface. a threaded member having a threaded portion protruding from the cylinder body toward the side opposite to the second clutch surface; one end of the threaded member is screwed into the threaded portion with one end exposed to the outside from the cylinder body; A hydraulic chamber is defined between the first piston and the clutch portion to generate hydraulic pressure when hydraulic pressure is activated, whereby hydraulic pressure is supplied to the hydraulic pressure chamber. Then, the first piston operates, the first clutch surface and the second clutch surface separate, the screw member and the adjusting member move integrally in the direction away from the first clutch surface, and the second piston Activate. As a result, the first brake shoe and the second brake shoe expand around the anchor member and come into sliding contact with the brake drum to enter a braking state.

When the braking clearance between the brake drum and the first brake shoe and between the brake drum and the second brake shoe is within the appropriate range, when the brake is released, the spring force of the return spring will cause the first brake shoe and the second brake shoe to close. The two brake shoes are urged in the direction of diameter reduction and return to their initial positions, and the first piston, second piston, adjustment member, and screw member each return to their initial positions. On the other hand, if the linings of the first and second brake shoes wear out and the braking gap becomes wider than the appropriate range, the movement distance of the first and second pistons will decrease due to the threaded engagement between the threaded portion and the adjustment member. When the amount of backlash is exceeded and the braking is released, the threaded member moves beyond the amount of backlash while rotating around the axis of the threaded member until the second clutch surface contacts the first clutch surface. Abuts against the first clutch surface. Along with this, the adjustment member moves toward the tip of the threaded portion, increases the distance in the cylinder axial direction between the first piston and the second piston, and automatically maintains the braking gap within an appropriate range. be able to.

Further, the electric actuator includes a motor and a reduction gear rotated by the motor, and a gear portion that meshes with the reduction gear is formed on the outer periphery of one end of the adjustment member, so that by operating the motor, the reduction gear is rotated. and the adjusting member is rotated via the gear portion and moved to the tip side of the threaded portion. Along with this, the adjustment member pushes the second piston, presses the second brake shoe to expand it, and brings it into sliding contact with the brake drum, thereby enabling the parking brake state.

3 is a sectional view taken along line II in FIG. 2. FIG. 1 is a front view of an electric parking brake device showing one embodiment of the present invention.

FIGS. 1 and 2 are diagrams showing one embodiment of an electric parking brake device of the present invention. In the electric parking brake device 1, a pair of first brake shoes 3 and a second brake shoe 4 are arranged symmetrically inside a back plate 2 bolted to a vehicle body (not shown). , 4 are arranged so as to be expandable, with one end portions 3a, 4a serving as expansion sides, and the other ends 3b, 4b serving as pivot points.

Both brake shoes 3 and 4 include webs 3c and 4c arranged parallel to the back plate 2, rims 3d and 4d fixed to the outer edges of the webs 3c and 4c and orthogonal to the webs 3c and 4c, and rims 3d and 4d that are perpendicular to the webs 3c and 4c. It is formed by linings 3e and 4e attached to the outer circumferential surfaces of the rims 3d and 4d, and approximately middle portions of the webs 3c and 4c are resiliently pressed against the back plate 2 by shoe hold pins 5a and 5a and shoe hold springs 5b and 5b. held.

A wheel cylinder 6 is provided between one end of the first brake shoe 3 and the second brake shoe 4 for expanding the first brake shoe 3 and the second brake shoe 4, and a wheel cylinder 6 is provided between the other end of the first brake shoe 3 and the second brake shoe 4. An anchor member 7 serving as an expansion fulcrum for the brake shoe 3 and the second brake shoe 4 is disposed, respectively. Between the first brake shoe 3 and the second brake shoe 4, return springs 8a and 8b are stretched between the inside of the wheel cylinder 6 and the outside of the anchor member 7, so that both brake shoes 3 and 4 are kept in tension at all times. It is biased in the direction of diameter reduction.

The foil cylinder 6 has a cylinder hole 6b formed through a cylinder body 6a bolted to the back plate 2, and a first piston 9 and an automatic braking gap adjustment mechanism 10 are accommodated in the cylinder hole 6b. The braking gap automatic adjustment mechanism 10 includes a screw member 11 that comes into contact with the first piston 9, and an adjustment member 12 that is screwed onto the screw member 11 with one end 12a exposed to the outside from the cylinder body 6a. The second piston 13 comes into contact with one end 12a of the adjusting member 12.

The first piston 9 is formed into a cylindrical shape that slides within the cylinder hole 6b and has a slightly smaller diameter than the cylinder hole 6b. On the inner peripheral side of the first piston 9, there is a first clutch surface 9b formed in the shape of a concave truncated cone that opens at the base end surface 9a on the inside of the cylinder body and gradually becomes smaller in diameter toward the distal end. Further, a housing recess 9c is formed on the central axis of the tip of the first clutch surface 9b. Further, a connecting portion 9d that connects the web 3c of the first brake shoe 3 is formed at the tip of the first piston 9, and a ventilation hole 9e that opens between the connecting portion 9d and the bottom surface of the accommodation recess 9c is formed. It is formed. Furthermore, a first seal groove 9f is formed in the outer peripheral surface of the base end side of the first piston 9, and a first cup seal 14 is fitted into the first seal groove 9f. Further, a first dust boot groove 9g is formed on the outer peripheral surface of the tip side of the first piston 9, and a second dust boot groove 6c is formed on the outer peripheral surface of one end of the cylinder body 6a. One end of the dust boot 15 is fitted into the second dust boot groove 6c, and the other end of the dust boot 15 is fitted into the second dust boot groove 6c.

The second piston 13 includes a cylindrical main body portion 13a connected to a connecting recess 12b opening at one end side of the adjusting member 12, which will be described later, a large diameter flange portion 13b protruding from one end surface of the adjusting member 12, and a second piston 13. A connecting portion 13c that connects the web 4c of the brake shoe 4 is provided. Further, a second seal groove 13d is formed on the outer peripheral surface of the main body portion 13a, and a first O-ring 16 is fitted into the second seal groove 13d.

The screw member 11 is integrally provided with a clutch portion 11a on the first piston side and a male thread portion 11b (threaded portion) on the second piston side. The clutch portion 11a includes a cylindrical portion 11c that is formed to have a slightly smaller diameter than the cylinder hole 6b that slides in the cylinder hole 6b, and a cylindrical portion 11c that protrudes from a distal end surface 11d (first piston side surface) of the cylindrical portion 11c, and is connected to the first piston. A protrusion 11e formed in a convex truncated cone shape whose diameter gradually becomes smaller toward 9 and a small diameter cylindrical part 11f protruding from the tip of the protrusion 11e are coaxially formed, and the outer surface of the protrusion 11e The second clutch surface 11g comes into contact with the first clutch surface 9b, and the small diameter cylindrical portion 11f is accommodated in the accommodation recess 9c of the first piston 9. Further, a third seal groove 11h is formed on the outer peripheral surface of the cylindrical portion 11c, and the second cup seal 17 is fitted into the third seal groove 11h. Further, a fourth seal groove 11i is formed in the outer peripheral surface of the small diameter cylindrical portion 11f, and the third cup seal 18 is fitted into the fourth seal groove 11i.

The male threaded portion 11b protrudes from the base end surface 11j (second piston side surface) of the clutch portion 11a toward the second piston side (the side opposite to the second clutch surface) on the central axis of the cylindrical portion 11c. Further, a hydraulic pressure chamber 19 is defined between the base end side of the first piston 9 and the distal end surface 11d of the cylindrical portion 11c, to which hydraulic fluid is supplied via a union hole 6d formed in the cylinder body 6a. Furthermore, a space E1 is formed between the bottom surface of the accommodation recess 9c of the first piston 9 and the tip surface of the small diameter cylindrical portion 11f of the screw member 11.

The adjusting member 12 includes a cylindrical portion 12c that is formed to have a slightly smaller diameter than the cylinder hole 6b that slides inside the cylinder hole 6b, and the one end portion 12a that projects from the cylinder body 6a and is exposed to the outside. 12a is formed to have a larger diameter than the outer diameter of the cylindrical portion 12c. The cylindrical portion 12c has a female threaded portion 12d on the inner circumferential side thereof, which is threaded onto the male threaded portion 11b, and is formed on the central axis of the cylindrical portion 12c, and is continuous with the female threaded portion 12d and opens at the distal end surface of the one end portion 12a. The connecting recess 12b is formed, and the distal end side of the male threaded portion 11b is accommodated in the connecting recess 12b, and the main body 13a of the second piston 13 is connected via the first O-ring 16. Further, a fifth seal groove 12e is formed on the outer periphery of the cylindrical portion 12c, and a second O-ring 20 is fitted into the fifth seal groove 12e. Further, a gear portion 12f that meshes with the reduction gear 22d of the electric parking brake mechanism 21 is formed on the outer circumferential surface of the one end portion 12a, and the outer end surface of the one end portion 12a and the large diameter flange portion 13b of the second piston 13 are connected to each other. A thrust bearing 23 is interposed between them.

The electric parking brake mechanism 21 includes a motor 24 and reduction gears 22a, 22b, 22c, and 22d rotated by the motor 24, and the reduction gear 22d connects to the back plate 2 through a connection hole 2a formed in the back plate. protrudes inward and meshes with the gear portion 12f of the adjusting member 12. Also. The motor 24 and the reduction gears 22a, 22b, 22c, and 22d are housed in a case 26 attached to the outer surface of the back plate 2 at a position corresponding to the foil cylinder 6 via a seal member 25.

When the foil cylinder 6 of the electric parking brake device 1 formed as described above is not braking, the first piston 9 and the second piston 13 are connected to each other by the springs of the return springs 8a and 8b, as shown in FIG. The force urges the foil cylinder 6 inward, and as a result, the first clutch surface 9b of the first piston 9 and the second clutch surface 11g of the screw member 11 come into contact with each other. There is.

During hydraulic operation, when hydraulic pressure is supplied from the union hole 6d of the foil cylinder 6 to the hydraulic pressure chamber 19, the first piston 9 and the second piston 13 via the screw member 11 and the adjusting member 12, The return springs 8a and 8b move in directions away from each other against the elastic force, and as a result, the first brake shoe 3 and the second brake shoe 4 expand around the anchor member 7, and the lining 3e and 4e are brought into sliding contact with the inner peripheral surface of the brake drum to perform a braking operation. When the brake is released, the first brake shoe 3 and the second brake shoe 4 return to their initial state due to the elastic force of the return springs 8a and 8b.

At this time, when the braking gap between the brake drum and the linings 3e and 4e of the first brake shoe 3 and the second brake shoe 4 is within an appropriate range, the first piston 9 and the second piston 13 move. The distance is within the backlash amount of the screw engagement between the male threaded portion 11b of the threaded member 11 of the automatic braking gap adjustment mechanism 10 and the female threaded portion 12d of the adjustment member 12, and the first piston 9 and the second piston 13 are initially The first clutch surface 9b and the second clutch surface 11g come into contact with each other.

When the linings 3e and 4e are worn and the braking gap becomes wider than the appropriate range, the moving distance of the first piston 9 and the second piston 13 becomes larger than the amount of backlash when screwed into the female threaded portion 12d of the adjusting member 12. When the brake becomes larger and the brake is released, the screw member 11 moves beyond the amount of backlash while rotating around the central axis of the screw member 11 by the time the second clutch surface 11g comes into contact with the first clutch surface 9b. and comes into contact with the first clutch surface 9b. Along with this, the adjustment member 12 moves toward the distal end side of the male threaded portion 11b, increasing the distance in the cylinder axial direction between the first piston 9 and the second piston 13, and adjusting the braking gap to an appropriate range. maintain.

On the other hand, when entering the parking brake state, the motor 24 is operated and the reduction gear 22a is rotated in one direction, thereby being decelerated via the reduction gears 22b, 22c, and 22d, and meshed with the reduction gear 22d. Via the gear portion 12f of the adjusting member 12, the adjusting member 12 rotates around the female threaded portion 12d while moving toward the distal end side of the male threaded portion 11b and presses the second piston 13. As a result, the second brake shoe 4 is expanded around the anchor member 7, and the lining 4e is brought into sliding contact with the inner circumferential surface of the brake drum, resulting in a parking brake state. Further, by operating the motor 24 and rotating the reduction gear 22a in the other direction, the adjusting member 12 is returned to the initial position and the parking brake state is released.

By forming the present embodiment as described above, an automatic braking gap adjustment mechanism 10 consisting of a screw member 11 and an adjustment member 12 is disposed between the first piston 9 and the second piston 13 of the foil cylinder 6. At the same time, one end 12a of the adjustment member 12 is exposed to the outside from the cylinder body 6a of the foil cylinder 6, and the reduction gear 22f of the electric parking brake mechanism 21 is meshed with the gear portion 12f formed on the one end 12a. Therefore, since the electric parking brake mechanism 21 can be configured using the automatic brake gap adjustment mechanism 10, the automatic brake gap adjustment mechanism 10 and the electric parking brake mechanism 21 can be configured with a small number of parts. In addition, when the hydraulic brake state is released and the brake state is changed to the electric parking brake state, the parking brake force is generated by the operation of the second piston 13 used for the hydraulic pressure operation. Braking force can be generated smoothly.

Furthermore, the screw member 11 and adjustment member 12 that constitute the automatic braking gap adjustment mechanism 10 and the electric parking brake mechanism 21 are arranged in the cylinder body 6a of the wheel cylinder 6, and the motor 24 of the electric parking brake mechanism 21 and By arranging the reduction gears 22a, 22b, 22c, and 22d at positions corresponding to the foil cylinders 6 on the outer surface of the back plate 2, the parts constituting the braking gap automatic adjustment mechanism 10 and the electric parking brake mechanism 21 can be The automatic braking gap adjustment mechanism 10 and the electric parking brake mechanism 21 can be provided in a small space by concentrating them in the body and around the cylinder body, and the layout can be improved.

Note that the automatic braking gap adjustment mechanism of the electric parking brake device of the present invention is not limited to the above-mentioned embodiment, and may vary depending on the arrangement of the first piston and the first brake shoe, and the arrangement of the second piston and the second brake shoe. Alternatively, the screw member and the adjusting member may be reversed and placed inside the cylinder body. That is, the first piston and the first brake shoe correspond to the second piston and the second brake shoe in the claims, and the second piston and the second brake shoe correspond to the first piston and the first brake shoe in the claims. It will be equivalent to . Furthermore, the braking gap automatic adjustment mechanism may be such that the adjusting member is provided with a male threaded portion protruding toward the first piston, and the threaded member is provided with a female threaded portion.

DESCRIPTION OF SYMBOLS 1... Electric parking brake device, 2... Back plate, 2a... Connection hole, 3... First brake shoe, 3a... One end, 3b... Other end, 3c... Web, 3d... Rim, 3e... Lining, 4... Third 2 Brake shoe, 4a... One end, 4b... Other end, 4c... Web, 4d... Rim, 4e... Lining, 5a... Shoe hold pin, 5b... Shoe hold spring, 6... Foil cylinder, 6a... Cylinder body, 6b ...Cylinder hole, 6c...Second dust boot groove, 6d...Union hole, 7...Anchor member, 8a, 8b...Return spring, 9...First piston, 9a...Base end surface, 9b...First clutch surface, 9c...Accommodation Recessed portion, 9d...Connecting portion, 9e...Vent hole, 9f...First seal groove, 9g...First dust boot groove, 10...Braking gap automatic adjustment mechanism, 11...Threaded member, 11a...Clutch part, 11b...Male thread part, 11c...Cylindrical portion, 11d...Top surface, 11e...Protrusion, 11f...Small diameter cylindrical portion, 11g...Second clutch surface, 11h...Third seal groove, 11i...Fourth seal groove, 11j...Proximal end surface, 12...Adjustment Members, 12a... One end, 12b... Connection recess, 12c... Cylindrical part, 12d... Female threaded part, 12e... Fifth seal groove, 12f... Gear part, 13... Second piston, 13a... Main body part, 13b... Large diameter flange Part, 13c...Connection part, 13d...Second seal groove, 14...First cup seal, 15...Dust boot, 16...First O-ring, 17...Second cup seal, 18...Third cup seal, 19...Hydraulic pressure Chamber, 20... Second O-ring, 21... Electric parking brake mechanism, 22a, 22b, 22c, 22d... Reduction gear, 23... Thrust bearing, 24... Motor, 25... Seal member, 26... Case

Claims (3)

A first brake shoe and a second brake shoe that are in sliding contact with the brake drum are arranged in an expandable manner on the inside of a back plate that is fixed to the vehicle body, and one end portion of the first brake shoe and the second brake shoe is arranged so as to be expandable. A foil cylinder having a first piston that abuts the first brake shoe and a second piston that abuts the second brake shoe is disposed between them, and an anchor member serving as an expansion center is disposed between the other end thereof. , a return spring is provided between the first brake shoe and the second brake shoe that biases the first brake shoe and the second brake shoe in a radially contracting direction, and the brake drum and the first brake An electric parking brake device comprising: an automatic braking gap adjustment mechanism that adjusts the braking gap between the brake drum and the second brake shoe; and an electric parking brake mechanism that electrically puts the parking brake in the parking brake state. In,
The braking gap automatic adjustment mechanism is disposed between the first piston and the second piston with one end exposed to the outside from the cylinder body of the foil cylinder, and is arranged between the first piston and the second piston. Adjusting the distance in the cylinder axial direction between the cylinder and the piston, bringing the second piston into contact with the one end, and connecting an electric actuator of an electric parking brake mechanism to the one end, and driving the electric actuator. An electric parking brake device characterized in that the second piston is actuated to enter a parking state. The first piston includes a first clutch surface at an inner end of the cylinder body,
The braking gap automatic adjustment mechanism includes a clutch portion including a second clutch surface that comes into contact with the first clutch surface, and a threaded member comprising a threaded portion formed on a side of the clutch portion opposite to the second clutch surface; an adjusting member that is screwed into the threaded portion with one end exposed to the outside from the cylinder body, and that has the one end abutted on the second piston via a bearing, the first piston and the clutch portion 2. The electric parking brake device according to claim 1, wherein a hydraulic pressure chamber is defined between and for generating hydraulic pressure during hydraulic operation. 3. The electric actuator includes a motor and a reduction gear rotated by the motor, and a gear portion that meshes with the reduction gear is formed on the outer periphery of the one end of the adjustment member. Electric parking brake device.

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