JP2021154827A - Electric parking brake device - Google Patents

Abstract

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. SOLUTION: An electric parking brake device 1 includes an automatic braking gap adjustment mechanism 10 and an electric parking brake mechanism 21. The braking gap automatic adjustment mechanism 10 is disposed between the first piston 9 and the second piston 13 with one end 12a exposed to the outside from the cylinder body 6a of the foil cylinder 6, and is arranged between the first piston 9 and the second piston 13. The distance between the cylinder and the piston 13 in the axial direction of the cylinder is adjusted. The second piston 13 is brought into contact with one end 12a of the automatic braking gap adjustment mechanism 10, and a gear part 12f is provided at the one end 12a, and the reduction gear 22d of the electric parking brake mechanism 21 is connected to the gear part 12f. [Selection diagram] Figure 1

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 adjusting mechanism and an electric parking brake mechanism.

Conventionally, there is an electric parking brake device provided with an electric parking brake mechanism in which an extension mechanism arranged between the first piston and the second piston in the wheel cylinder is operated by an electric actuator to bring the vehicle into a parking state. (See, for example, Patent Document 1). Also, 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, this is applied. Some have an automatic braking gap adjusting mechanism that automatically adjusts (see, for example, Patent Document 2).

Japanese Patent No. 6254697 Special Fair 1-51703 Gazette

However, in the above-mentioned Patent Document 1, although the electric parking brake mechanism using the foil cylinder is provided, the braking gap automatic adjustment mechanism is not provided. Further, in Patent Document 2, although the braking gap automatic adjustment mechanism using the foil cylinder is provided, the electric parking brake mechanism is not provided.

Therefore, an object of the present invention is to provide an electric parking brake device including an automatic braking gap adjusting mechanism using a wheel cylinder and an electric parking brake mechanism.

In order to achieve the above object, in the electric parking brake device of the present invention, the first brake shoe and the second brake shoe that are in sliding contact with the brake drum are arranged on the inner side of the back plate fixed to the vehicle body so as to be expandable. A wheel cylinder provided with a first piston in contact with the first brake shoe and a second piston in contact with the second brake shoe is provided between one end of the first brake shoe and the second brake shoe. Anchor members serving as expansion centers are arranged between the other ends, and the first brake shoe and the second brake shoe are placed between the first brake shoe and the second brake shoe in the radial direction. An automatic braking gap adjustment mechanism that provides an urging return spring and adjusts the braking gap between the brake drum and the first brake shoe and between the brake drum and the second brake shoe, and electric parking. In the electric parking brake device provided with the electric parking brake mechanism in the braking state, the braking gap automatic adjustment mechanism has the first piston and the first piston in a state where one end is exposed to the outside from the cylinder body of the wheel cylinder. Arranged between the two pistons, the distance in the cylinder axial direction between the first piston and the second piston is adjusted, the second piston is brought into contact with the one end portion, and the one end portion is provided. The electric actuator of the electric parking brake mechanism is connected to the electric parking brake mechanism, and the second piston is operated by driving the electric actuator to bring the second piston into a parking state.

Further, the first piston is provided with a first clutch surface at an end portion on the inner side of the cylinder body, and the braking gap automatic adjustment mechanism is a clutch portion provided with a second clutch surface that abuts on the first clutch surface. And a screw member including a screw portion formed on the anti-second clutch surface side of the clutch portion, and one end portion is screwed into the screw portion in a state of being exposed to the outside from the cylinder body, and the one end portion is screwed into the screw portion. It is preferable that an adjusting member that comes into contact with the second piston via a bearing is provided, and a hydraulic chamber that generates hydraulic pressure during hydraulic pressure operation is defined between the first piston and the clutch portion. ..

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 portion of the adjusting member.

According to the electric parking brake device of the present invention, the electric parking brake mechanism is configured by utilizing the braking gap automatic adjustment mechanism which 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, since the parking brake force is generated by the operation of the same piston as the piston used for the hydraulic operation at the time of operation replacement that shifts to the parking brake state by electric after releasing the braking state due to the hydraulic operation. The parking brake force can be generated smoothly.

Further, the parts constituting the braking gap automatic adjustment mechanism and the electric parking brake mechanism are integrated in the cylinder body of the wheel cylinder and around the cylinder body, and the braking gap automatic adjustment mechanism and the electric parking brake mechanism are combined in a small space. Therefore, it is possible to improve the layout.

Further, the first piston is provided with a first clutch surface at the end on the inner side of the wheel cylinder, and the braking gap automatic adjustment mechanism is a clutch portion having a second clutch surface that abuts on the first clutch surface, and the clutch portion. A screw member having a screw portion protruding from the second clutch surface side and one end portion exposed to the outside from the cylinder body are screwed into the screw portion and one end portion is a bearing on the second piston. A hydraulic chamber is defined between the first piston and the clutch portion to generate hydraulic pressure during hydraulic pressure operation, so that hydraulic pressure is supplied to the hydraulic chamber. Then, as the first piston operates, the first clutch surface and the second clutch surface are separated from each other, and the screw member and the adjusting member move integrally in a direction away from the first clutch surface, and the second piston To operate. 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 the braking state.

When the braking gap between the brake drum and the first brake shoe and between the brake drum and the second brake shoe is within an appropriate range, when the braking is released, the spring force of the return spring causes the first brake shoe and the first brake shoe. 2 The brake shoe is urged in the radial direction to return to the initial position, and the first piston, the second piston, the adjusting member, and the screw member each return to the initial position. On the other hand, when the linings of the first brake shoe and the second brake shoe are worn and the braking gap becomes wider than the appropriate range, the moving distance between the first piston and the second piston becomes the screwing between the screw portion and the adjusting member. When the backlash amount is exceeded and the braking is released, the screw member moves beyond the backlash amount while rotating around the axis of the screw member until the second clutch surface comes into contact with the first clutch surface. It comes into contact with the first clutch surface. Along with this, the adjusting member moves to the tip side 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 reduction gear is formed by forming a gear portion that meshes with the reduction gear on the outer periphery of one end of the adjusting member to operate the motor. The adjusting member is rotated via the gear portion and moved to the tip side of the screw portion. Along with this, the adjusting member pushes the second piston, presses the second brake shoe to expand it, and slides it into contact with the brake drum, so that the parking brake state can be obtained.

FIG. 2 is a cross-sectional view taken along the line II of FIG. It is a front view of the electric parking brake device which shows an example of one embodiment of this invention.

1 and 2 are views showing an example of one form of the 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 symmetrically arranged inside a back plate 2 bolted to a vehicle body (not shown), and both brake shoes 3 are arranged. , 4 are arranged so that one end portions 3a and 4a can be expanded and the other end portions 3b and 4b can be expanded as rotation fulcrums.

Both brake shoes 3 and 4 have webs 3c and 4c arranged parallel to the back plate 2, and rims 3d and 4d fixed to the outer edges of the webs 3c and 4c and orthogonal to the webs 3c and 4c. It is formed by linings 3e and 4e attached to the outer peripheral surfaces of the rims 3d and 4d, and the substantially intermediate portion of the webs 3c and 4c is repelled by the shoe hold pins 5a and 5a and the shoe hold springs 5b and 5b on the back plate 2. It is possessed.

A foil cylinder 6 for expanding the first brake shoe 3 and the second brake shoe 4 is provided between one end of the first brake shoe 3 and the second brake shoe 4, and a first brake shoe is provided between the other ends. Anchor members 7 serving as expansion fulcrum points for 3 and the 2nd brake shoe 4 are arranged respectively. Return springs 8a and 8b are stretched between the first brake shoe 3 and the second brake shoe 4 on the inside of the foil cylinder 6 and the outside of the anchor member 7, and both brake shoes 3 and 4 are always used. It is urged in the contraction direction.

The foil cylinder 6 is formed by penetrating a cylinder hole 6b through a cylinder body 6a bolted to a back plate 2, and a first piston 9 and a braking gap automatic adjusting mechanism 10 are housed in the cylinder hole 6b. The braking gap automatic adjustment mechanism 10 includes a screw member 11 that abuts on the first piston 9, and an adjusting member 12 that is screwed into the screw member 11 with one end portion 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 in a cylindrical shape having a diameter slightly smaller than that of the cylinder hole 6b, which slides in the cylinder hole 6b. On the inner peripheral side of the first piston 9, a first clutch surface 9b formed in a concave truncated cone shape that opens in the base end surface 9a on the inner side of the cylinder body and gradually decreases in diameter toward the tip side is on the central axis. In addition, a housing recess 9c is formed on the central axis of the tip of the first clutch surface 9b. Further, at the tip of the first piston 9, a connecting portion 9d for connecting the web 3c of the first brake shoe 3 is formed, and a ventilation hole 9e that opens between the connecting portion 9d and the bottom surface of the accommodating recess 9c is provided. It is formed. Further, a first seal groove 9f is formed on the outer peripheral surface of the first piston 9 on the base end side, and the first cup seal 14 is fitted in the first seal groove 9f. Further, a first dust boot groove 9g is formed on the outer peripheral surface on the tip end 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 to 9 g, and the other end of the dust boot 15 is fitted to the second dust boot groove 6c.

The second piston 13 includes a cylindrical main body portion 13a connected to a connecting recess 12b that opens on one end side of the adjusting member 12, a large-diameter flange portion 13b protruding from one end surface of the adjusting member 12, and a second piston 13. It is provided with a connecting portion 13c for connecting the web 4c of the brake shoe 4. A second seal groove 13d is formed on the outer peripheral surface of the main body 13a, and the first O-ring 16 is fitted in 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 screw portion 11b (screw portion) on the second piston side. The clutch portion 11a protrudes from the cylindrical portion 11c formed to have a diameter slightly smaller than that of the cylinder hole 6b sliding in the cylinder hole 6b and the tip surface 11d (the side surface of the first piston) of the cylindrical portion 11c, and is the first piston. A protrusion 11e formed in a convex truncated cone shape that gradually decreases in diameter toward 9, and a small-diameter cylindrical portion 11f protruding from the tip of the protrusion 11e are coaxially formed, and the outer surface of the protrusion 11e is formed. Is the second clutch surface 11g that comes into contact with the first clutch surface 9b, and the small-diameter cylindrical portion 11f is accommodated in the accommodating recess 9c of the first piston 9. 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 on 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 screw portion 11b projects from the base end surface 11j (second piston side surface) of the clutch portion 11a toward the second piston side (anti-second clutch surface side) on the central axis of the cylindrical portion 11c. Further, between the base end side of the first piston 9 and the tip end surface 11d of the cylindrical portion 11c, a hydraulic chamber 19 in which the hydraulic fluid is supplied through the union hole 6d formed in the cylinder body 6a is defined. Further, a space portion E1 is formed between the bottom surface of the accommodating 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 formed having a diameter slightly smaller than that of the cylinder hole 6b sliding in the cylinder hole 6b, and one end portion 12a protruding from the cylinder body 6a and exposed to the outside. 12a is formed to have a diameter larger than the outer diameter of the cylindrical portion 12c. On the inner peripheral side of the cylindrical portion 12c, a female screw portion 12d screwed to the male screw portion 11b is formed on the central axis of the cylindrical portion 12c, and is continuous with the female screw portion 12d and opens to the tip surface of one end portion 12a. The connecting recess 12b is formed, and the tip end side of the male screw portion 11b is accommodated in the connecting recess 12b, and the main body portion 13a of the second piston 13 is connected via the first O-ring 16. A fifth seal groove 12e is formed on the outer periphery of the cylindrical portion 12c, and the 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 peripheral 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 formed. A thrust bearing 23 is interposed between them.

The electric parking brake mechanism 21 includes a motor 24 and reduction gears 22a, 22b, 22c, 22d rotated by the motor 24, and the reduction gear 22d is provided through a connection hole 2a formed in the back plate to the back plate 2 It 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.

In the wheel cylinder 6 of the electric parking brake device 1 formed as described above, when not braking, as shown in FIG. 1, the first piston 9 and the second piston 13 repel the return springs 8a and 8b. The force causes the wheel cylinder 6 to be urged to the inner side, respectively, and the first clutch surface 9b of the first piston 9 and the second clutch surface 11g of the screw member 11 are in contact with each other. There is.

When hydraulic pressure is supplied to the hydraulic chamber 19 from the union hole 6d of the wheel cylinder 6 during hydraulic pressure operation, the first piston 9 and the second piston 13 are moved via the screw member 11 and the adjusting member 12. The return springs 8a and 8b move in a direction away from each other against the elastic force of the return springs 8a and 8b, and along with this, the first brake shoe 3 and the second brake shoe 4 expand around the anchor member 7 and lining. Braking operation is performed by sliding 3e and 4e against the inner peripheral surface of the brake drum. When the braking is released, the first brake shoe 3 and the second brake shoe 4 return to the 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 between the male screw portion 11b of the screw member 11 of the braking gap automatic adjustment mechanism 10 and the female screw portion 12d of the adjusting member 12, and the first piston 9 and the second piston 13 are initially The position returns to the above position, and 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 between the first piston 9 and the second piston 13 becomes larger than the backlash amount of the screwing with the female screw portion 12d of the adjusting member 12. When it becomes large and the braking is released, the screw member 11 moves beyond the backlash amount while rotating around the central axis of the screw member 11 until the second clutch surface 11g comes into contact with the first clutch surface 9b. Then, it comes into contact with the first clutch surface 9b. Along with this, the adjusting member 12 moves to the tip end side of the male screw portion 11b, increases the distance in the cylinder axial direction between the first piston 9 and the second piston 13, and makes the braking gap within an appropriate range. maintain.

On the other hand, in the parking brake state, the motor 24 is operated to rotate the reduction gear 22a in one direction, so that the speed is reduced via the reduction gears 22b, 22c, 22d and meshes with the reduction gear 22d. The adjusting member 12 moves to the tip end side of the male threaded portion 11b while rotating around the female threaded portion 12d via the gear portion 12f of the adjusting member 12, and presses the second piston 13. As a result, the second brake shoe 4 expands around the anchor member 7, and the lining 4e is brought into sliding contact with the inner peripheral surface of the brake drum to bring the parking brake state. Further, by operating the motor 24 and rotating the reduction gear 22a to the other side, the adjusting member 12 is returned to the initial position and the parking brake state is released.

By forming the example of this embodiment as described above, the automatic braking gap adjusting mechanism 10 composed of the screw member 11 and the adjusting member 12 is arranged between the first piston 9 and the second piston 13 of the wheel cylinder 6. At the same time, one end 12a of the adjusting member 12 was exposed to the outside from the cylinder body 6a of the wheel cylinder 6, and the reduction gear 22f of the electric parking brake mechanism 21 was meshed with the gear 12f formed on the one end 12a. Therefore, since the electric parking brake mechanism 21 can be configured by using the braking gap automatic adjusting mechanism 10, the braking gap automatic adjusting mechanism 10 and the electric parking brake mechanism 21 can be configured with a small number of parts. Further, when the operation is replaced by moving to the parking brake state by electric power after releasing the brake state by hydraulic pressure operation, the parking brake force is generated by the operation of the second piston 13 used for hydraulic pressure operation. Therefore, parking is performed. Braking force can be generated smoothly.

Further, the screw member 11 and the adjusting member 12 constituting the braking gap automatic 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 the motor 24 By arranging the reduction gears 22a, 22b, 22c, and 22d at positions corresponding to the wheel cylinder 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 are made into cylinders. The braking gap automatic adjustment mechanism 10 and the electric parking brake mechanism 21 can be provided in the body and around the cylinder body in a small space, and the layout can be improved.

The braking gap automatic adjustment mechanism of the electric parking brake device of the present invention is not limited to the above-described embodiment, and includes the arrangement of the first piston and the first brake shoe and the arrangement of the second piston and the second brake shoe. May be reversed and the screw member and the adjusting member may be arranged in the cylinder body in an inverted state. 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. Is equivalent to. Further, the braking gap automatic adjustment mechanism may be one in which the adjusting member is provided with a male threaded portion protruding toward the first piston side, and the threaded member is provided with a female threaded portion.

1 ... Electric parking brake device, 2 ... Back plate, 2a ... Connection hole, 3 ... First brake shoe, 3a ... One end, 3b ... The other end, 3c ... Web, 3d ... Rim, 3e ... Lining, 4 ... 2 Brake shoe, 4a ... one end, 4b ... other end, 4c ... web, 4d ... rim, 4e ... lining, 5a ... shoe hold pin, 5b ... shoe hold spring, 6 ... wheel 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 ... Accommodating Recess, 9d ... Connecting part, 9e ... Vent hole, 9f ... First seal groove, 9g ... First dust boot groove, 10 ... Braking gap automatic adjustment mechanism, 11 ... Screw member, 11a ... Clutch part, 11b ... Male thread part, 11c ... Cylindrical part, 11d ... Tip surface, 11e ... Protrusion part, 11f ... Small diameter cylindrical part, 11g ... 2nd clutch surface, 11h ... 3rd seal groove, 11i ... 4th seal groove, 11j ... Base end surface, 12 ... Adjust Member, 12a ... One end, 12b ... Connecting 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 ... Connecting part, 13d ... 2nd seal groove, 14 ... 1st cup seal, 15 ... Dust boot, 16 ... 1st O ring, 17 ... 2nd cup seal, 18 ... 3rd cup seal, 19 ... Hydraulic pressure Room, 20 ... 2nd 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)

The first brake shoe and the second brake shoe that are in sliding contact with the brake drum are arranged so as to be expandable on the inner side of the back plate fixed to the vehicle body, and one end of the first brake shoe and the second brake shoe. A wheel cylinder having a first piston that contacts the first brake shoe and a second piston that contacts the second brake shoe is arranged between them, and an anchor member that serves as an expansion center is arranged between the other ends. A return spring for urging the first brake shoe and the second brake shoe in the radial direction is provided between the first brake shoe and the second brake shoe, and the brake drum and the first brake are provided. An electric parking brake device including an automatic braking gap adjusting mechanism for adjusting the braking gap between the shoe and the brake drum and the second brake shoe, and an electric parking brake mechanism for electrically setting the parking brake state. In
The braking gap automatic adjustment mechanism is arranged between the first piston and the second piston in a state where one end is exposed to the outside from the cylinder body of the wheel cylinder, and the first piston and the second piston are arranged. The distance in the cylinder axial direction between the piston and the piston is adjusted, the second piston is brought into contact with the one end, and the electric actuator of the electric parking brake mechanism is connected to the one end, and the electric actuator is driven. , An electric parking brake device characterized in that the second piston is operated to bring the vehicle into a parking state. The first piston is provided with a first clutch surface at an end portion on the inner side of the cylinder body.
The braking gap automatic adjustment mechanism includes a screw member including a clutch portion having a second clutch surface that abuts on the first clutch surface, and a screw portion formed on the anti-second clutch surface side of the clutch portion. The first piston and the clutch portion are provided with an adjusting member in which one end portion is screwed into the screw portion in a state of being exposed to the outside from the cylinder body, and the one end portion abuts on the second piston via a bearing. The electric parking brake device according to claim 1, wherein a hydraulic chamber for generating hydraulic pressure is defined between the clutch and the clutch. 2. The electric actuator according to claim 2, further comprising a motor and a reduction gear rotated by the motor, and forming a gear portion that meshes with the reduction gear on the outer periphery of the one end portion of the adjusting member. Electric parking brake device.

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