JP7229635B2 - Drum brake structure - Google Patents

Description

The present invention relates to a drum brake structure in which a parking lever for an electric parking brake is arranged inside a drum.

2. Description of the Related Art A configuration in which a parking lever is arranged inside a drum is disclosed as an electric parking device for a drum brake of an automobile (see, for example, Patent Document 1). The parking lever is connected to, for example, a cable that pushes and pulls when driven by an electric actuator, and the cable is covered with a rubber cover that prevents water and foreign matter from entering. When the electric parking brake is actuated, the parking lever rotates about a predetermined rotation axis and is displaced radially inward of the drum.

When assembling a drum brake with such a structure, a back plate with brake parts such as shoes and a parking lever is attached to the vehicle body, and a hub bearing having a boss portion for fastening bolts is moved inward in the vehicle width direction. (For hub bearings, see Patent Document 2, for example). However, since the hub bearing is rotatable around the axle during this assembly, a positional deviation occurs in the rotational direction. It could be damaged.

Also, if the pulling stroke of the parking lever becomes excessive when the electric parking brake is actuated, the parking lever may unduly interfere with other parts, causing inconvenience such as the parking lever not returning to its original position even when the cable returns. rice field.

JP 2018-21575 A Japanese Patent No. 4725468

The present invention has been devised under the circumstances described above, and in a configuration in which the parking lever for the electric parking brake is arranged inside the drum, it prevents inconveniences that occur during assembly and operation of the electric parking brake. The main object is to provide a drum brake structure suitable for

In order to solve the above problems, the present invention employs the following technical means.

In the drum brake structure provided by the present invention, a parking lever for an electric parking brake and a boss portion of a hub bearing are arranged inside a drum, and the operation of an electric actuator rotates the parking lever around a predetermined rotation axis. In the drum brake structure configured to be displaced radially inward of the drum as a result, a concave portion is formed between the adjacent boss portions, and the inner peripheral side of the parking lever has a width direction of the vehicle. It is characterized in that a convex portion is formed that enters the concave portion when viewed and faces the concave portion with a predetermined gap therebetween.

In a drum brake structure provided by another aspect of the present invention, a parking lever for an electric parking brake and a retainer for a hub bearing are arranged inside a drum, and the operation of an electric actuator rotates the parking lever around a predetermined rotation axis. In the drum brake structure configured to be displaced inward in the radial direction of the drum, the retainer is formed with a recessed portion on the outer periphery thereof, and the parking lever is provided with a concave portion on the inner periphery thereof in the vehicle width direction. A convex portion is formed so as to enter the concave portion when viewed and face the concave portion with a predetermined gap therebetween. It is characterized in that an extending claw is provided.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

1 is a side view of an example of a drum brake structure according to the present invention, viewed from the outside in the vehicle width direction along the vehicle width direction; FIG. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, omitting part of the internal structure; It is a side view similar to FIG. 1 for demonstrating the operating state of a parking lever. FIG. 5 is a side view of another example of the drum brake structure according to the present invention, viewed from the outside in the vehicle width direction along the vehicle width direction; FIG. 5 is a cross-sectional view along line VV of FIG. 4 showing the retainer; FIG. 5 is a cross-sectional view taken along line VI-VI of FIG. 4, omitting part of the internal structure;

1 to 3 show an example of a drum brake structure according to the present invention. The drum brake structure A1 of the present embodiment relates to a configuration in which the drum brake 1 is equipped with an electric parking brake, and includes an electric actuator 3 for the electric parking brake.

The drum brake 1 includes a substantially disk-shaped back plate 11 fixed to the vehicle body and a drum 12 attached to the rotating axle. The drum brake 1 has a well-known structure, and a back plate 11 is assembled with a pair of shoes 14 that are rotatable about an anchor portion 13 provided at the bottom of the back plate 11 . The outer peripheral surface of each shoe 14 is provided with an arcuate lining 15 that is pressed against the inner peripheral surface 121 of the drum 12 when braking.

When the brake is applied, the upper ends of the pair of shoes 14 are pushed apart by driving the cylinder 16, and the lining 15 is pressed against the inner peripheral surface 121 of the drum 12 to generate a braking force. When the brake is released, the lining 15 is separated from the inner peripheral surface 121 of the drum 12 and no braking force is generated. A spring (not shown) is attached to the shoe 14 to bias the shoe 14 toward the brake release position. 1 and 3, the drum 12, the anchor portion 13, the shoe 14 and the lining 15 are shown in phantom lines. Also, in FIG. 2, the anchor portion 13, the shoe 14 and the lining 15 are omitted.

The back plate 11 is also assembled with a parking lever 17 operated by an electric actuator 3 for an electric parking brake. The parking lever 17 is rotatably supported around a rotation shaft 171 on the upper side. As shown in FIGS. 1 and 2, the parking lever 17 is arranged inside the drum 12 .

As shown in FIG. 1, a cable 18 is connected to the lower portion of the parking lever 17. As shown in FIG. The cable 18 is pushed and pulled through a screw mechanism (not shown) by driving the electric actuator 3 . A portion of the cable 18 is inserted into a guide pipe 19, and a bellows-shaped rubber cover 20 is attached to the tip of the guide pipe 19 in a sealed manner. Incidentally, as shown in FIG. 2, the side surface of the back plate 11 has a shape having irregularities as appropriate for mounting various parts. Also, in FIG. 2, the cable 18 and the rubber cover 20 are omitted.

As shown in FIG. 1 , a convex portion 172 is formed on the inner peripheral side of the parking lever 17 . The significance of the convex portion 172 will be described later.

Parking lever 17 communicates with shoe 14 via strut 21 . When the parking brake is applied, the electric actuator 3 operates to pull the cable 18 to the right in FIG. Here, as the parking lever 17 rotates, the strut 21 is pushed to the right in the drawing, and the shoe 14 is pushed radially outward to apply the brake. In FIG. 3, the parking lever 17 in a state where the parking brake is applied is indicated by a dashed line.

When the parking brake is released, the cable 18 is returned to the left side in FIG. 1, the shoe 14 is restored to its original position, and no braking force is generated. It should be noted that the electric parking brake maintains the applied or released state of the brake due to the friction of the screw mechanism even when the drive of the electric actuator 3 is stopped. The electric parking brake can be switched between a brake-applied state and a brake-released state by operating the electric actuator 3 .

The electric actuator 3 is supported by the back plate 11 and arranged inside the back plate 11 in the vehicle width direction (upper right side in FIG. 1).

As shown in FIG. 2, the wheel 4 is supported by hub bearings 5 . The hub bearing 5 includes an outer cylinder 51 fixed to the vehicle body and an inner cylinder 52 fixed to a rotating axle (not shown). The inner cylinder 52 is inserted into the outer cylinder 51 and a ball bearing, for example, is interposed between the inner cylinder 52 and the outer cylinder 51 . Thereby, the inner cylinder 52 is rotatably supported with respect to the outer cylinder 51 . A boss portion 53 for bolting is formed at the inner end of the outer cylinder 51 in the vehicle width direction W. As shown in FIG. As shown in FIGS. 1 and 2, the boss portion 53 is arranged inside the drum 12 . As shown in FIG. 1, the boss portions 53 protrude radially outward, and concave portions 54 are formed between the boss portions 53 that are vertically adjacent to each other. The inner cylinder 52, the drum 12 and the wheel 4 are integrally connected by hub bolts (not shown). In addition, in FIG. 2, the hub bearing 5 is indicated by a phantom line. 1 and 3, the inner cylinder 52 is omitted.

As can be seen from FIG. 1 , in this embodiment, the convex portion 172 formed on the inner peripheral side of the parking lever 17 enters the concave portion 54 of the hub bearing 5 when viewed in the vehicle width direction W. As shown in FIG. The convex portion 172 of the parking lever 17 faces the concave portion 54 of the hub bearing 5 with a predetermined gap C1 therebetween.

Next, the operation of this embodiment will be described.

In the drum brake structure A1 of the present embodiment, the convex portion 172 formed on the inner peripheral side of the parking lever 17 corresponds to the concave portion 54 formed between the adjacent boss portions 53 in the hub bearing 5 when viewed in the vehicle width direction W. getting into The convex portion 172 of the parking lever 17 faces the concave portion 54 of the hub bearing 5 across a predetermined gap C1. When the drum brake 1 is assembled, the back plate 11 incorporating the shoe 14, the parking lever 17, etc. is attached to the vehicle body, and the hub bearing 5 is moved inside in the vehicle width direction W to be set. During this assembly, the hub bearing 5 (the outer cylinder 51 and the inner cylinder 52) is relatively rotatable around the axle, and therefore positional displacement may occur in the rotational direction. According to the configuration having the concave portion 54 and the convex portion 172 described above, by aligning the convex portion 172 of the parking lever 17 so as to enter the concave portion 54 of the hub bearing 5 when viewed in the vehicle width direction W, the hub Assembly can be performed while positioning the bearing 5 (outer cylinder 51) in the rotational direction. As a result, for example, the boss portion 53 of the hub bearing 5 is prevented from coming into contact with surrounding parts such as the rubber cover 20, thereby preventing damage to the surrounding parts.

Further, according to the configuration in which the convex portion 172 is formed on the inner peripheral side of the parking lever 17, when the electric parking brake is operated, as can be understood from FIGS. When the lever 17 rotates by a predetermined angle, the convex portion 172 comes into contact with the outer peripheral portion 51A of the hub bearing 5 (outer cylinder 51). Therefore, an excessive pulling stroke of the parking lever 17 can be avoided, and the inconvenience of the parking lever 17 unduly interfering with other parts can be prevented.

4 to 6 show other examples of drum brake structures according to the present invention. note that. In these figures, elements that are the same as or similar to those in the above embodiment are denoted by the same reference numerals as in the above embodiment, and description thereof will be omitted as appropriate.

The drum brake structure A2 of this embodiment differs from the above embodiment mainly in the configuration of the hub bearing 5 and the configuration of the parking lever 17. As shown in FIG. As shown in FIG. 4, each element of the drum brake structure A2, such as the parking lever 17, the cable 18, the guide pipe 19, the rubber cover 20, and the electric actuator 3, is compared with the drum brake structure A1 of the above embodiment. are generally symmetrically arranged.

In the drum brake structure A2, the parking lever 17 is configured with a first lever 17A and a second lever 17B. As shown in FIG. 6, the first lever 17A and the second lever 17B are spaced apart by a predetermined dimension t2 in the vehicle width direction W. As shown in FIG. 4 and 6, the first lever 17A and the second lever 17B partially overlap each other when viewed in the vehicle width direction W. As shown in FIG. Although detailed illustration is omitted, the first lever 17A and the second lever 17B are linked so as to be integrally rotatable.

In the drum brake structure A<b>2 , a convex portion 172 and a pair of protrusions 173 are provided on the inner peripheral side of the parking lever 17 . The pair of protrusions 173 are provided on the second lever 17B and separated vertically when viewed in the vehicle width direction W. As shown in FIG. The significance of the pair of protrusions 173 and the like will be described later.

As shown in FIGS. 4 and 6 , the hub bearing 5 is configured with a retainer 55 . The retainer 55 holds a bearing 502 inside the housing 501 of the hub bearing 5 . The retainer 55 has a plate-like shape with an opening in the center, and is provided with a step so that the portion closer to the inner circumference is located on the outer side in the vehicle width direction W. As shown in FIG. A plurality of bolt holes 551 through which stud bolts 7 provided on the vehicle body are inserted are formed in a portion of the retainer 55 near the outer periphery. The axle shaft 6 is inserted into the opening of the retainer 55 .

As shown in FIG. 4 , a concave portion 57 is formed on the outer circumference 56 of the retainer 55 . In this embodiment, the concave portion 57 is formed between a pair of bolt holes 551 spaced apart vertically. A convex portion 172 formed on the inner peripheral side of the parking lever 17 enters the concave portion 57 of the retainer 55 when viewed in the vehicle width direction W. As shown in FIG. The convex portion 172 of the parking lever 17 faces the concave portion 57 of the retainer 55 with a predetermined gap C1 interposed therebetween.

In this embodiment, a claw portion 58 is also provided on the outer circumference 56 of the retainer 55 . As can be understood from FIGS. 4 to 6, the claw portion 58 is bent from the concave portion 57 and extends outward in the vehicle width direction W. As shown in FIG. As shown in FIG. 4 , the claw portion 58 is positioned between the pair of protrusions 173 provided on the parking lever 17 in the vehicle width direction W. As shown in FIG.

As shown in FIG. 6, in the drum brake structure A2, the height t1 from the inner end face of the retainer 55 in the vehicle width direction W to the tip of the claw portion 58 is equal to the dimension t2 between the first lever 17A and the second lever 17B. is greater than Further, the height t1 of the retainer 55 is larger than the dimension t3 from the tip of the stud bolt 7 to the parking lever 17 (second lever 17B).

Next, the operation of this embodiment will be described.

In the drum brake structure A2 of this embodiment, the convex portion 172 formed on the inner peripheral side of the parking lever 17 enters the concave portion 57 formed in the retainer 55 when viewed in the vehicle width direction W. The convex portion 172 of the parking lever 17 faces the concave portion 57 of the retainer 55 across a predetermined gap C1. When the drum brake 1 is assembled, the back plate 11 including the shoe 14, the parking lever 17, etc. is attached to the vehicle body, and the retainer 55 and the axle shaft 6 are set inside in the vehicle width direction W. During this assembly, the retainer 55 is rotatable about the axle, and thus can be displaced in the rotational direction. According to the configuration having the concave portion 57 and the convex portion 172 described above, the retainer 55 is positioned so that the convex portion 172 of the parking lever 17 enters the concave portion 57 of the retainer 55 when viewed in the vehicle width direction W. It is possible to assemble while positioning in the direction of rotation. As a result, for example, the outer circumference 56 of the retainer 55 is prevented from coming into contact with the surrounding parts such as the rubber cover 20, thereby preventing damage to the surrounding parts.

Further, in the drum brake structure A2, the retainer 55 is provided with claw portions 58 . The claw portion 58 is bent from the concave portion 57 and extends outward in the vehicle width direction W by a predetermined length. According to the configuration having such a claw portion 58, when the plate portion of the retainer 55 passes between the first lever 17A and the second lever 17B, the plate portion of the retainer 55 passes the second lever 17B. In the period from when the stud bolt 7 enters the bolt hole 551, improper rotation of the retainer 55 is restricted. Furthermore, according to the configuration in which the pair of projections 173 are provided on the parking lever 17, the claw portion 58 is locked by the pair of projections 173 with respect to rotation when the retainer 55 is set. Therefore, it is possible to more accurately restrict the rotation when the retainer 55 is set.

Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. The specific configuration of each part of the present invention can be changed in various ways.

A1, A2 Drum brake structure C1 Gap t1 Height t2 Dimension t3 Dimension W Vehicle width direction 1 Drum brake 11 Back plate 12 Drum 121 Inner peripheral surface 13 Anchor portion 14 Shoe 15 Lining 16 Cylinder 17 Parking lever 17A First lever 17B Second Lever 171 Rotating shaft 172 Projection 173 Projection 18 Cable 19 Guide pipe 20 Rubber cover 21 Strut 3 Electric actuator 4 Wheel 5 Hub bearing 501 Housing 502 Bearing 51 Outer cylinder 51A Peripheral part 52 Inner cylinder 53 Boss part 54 Recessed part 55 Retainer 551 bolt hole 56 outer circumference 57 concave portion 58 claw portion 6 axle shaft 7 stud bolt

Claims (1)

A parking lever for an electric parking brake and a retainer for a hub bearing are arranged inside the drum, and the operation of the electric actuator causes the parking lever to rotate about a predetermined rotation axis and displace radially inward of the drum. In the drum brake structure configured to
A concave portion is formed on the outer circumference of the retainer,
Formed on the inner peripheral side of the parking lever is a convex portion that enters the concave portion when viewed in the vehicle width direction and faces the concave portion with a predetermined gap therebetween,
A drum brake structure, wherein a pawl portion that is bent from the concave portion and extends outward in the vehicle width direction is provided on the outer periphery of the retainer .

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