JP7102645B2 - Drum brake structure - Google Patents

Description

The present invention relates to a drum brake structure in which an electric actuator for an electric parking brake is provided on a back plate of a drum brake.

As an electric parking device for an automobile drum brake, a structure in which an electric actuator is attached to a back plate is disclosed (see, for example, Patent Document 1). As shown in the same document, in order to secure a wide interior width of a vehicle with dimensional restrictions, the electric actuator for the electric parking brake is in a posture of intersecting the vehicle width direction and projecting outward in the radial direction of the drum brake. Provided.

However, when the electric actuator is provided in a posture of protruding outward in the radial direction of the drum brake, the gap between the inner peripheral surface of the wheel and the tip end portion of the electric actuator becomes relatively small. Then, for example, when snow or mud adheres to the inner surface of the wheel and accumulates, the deposit may interfere with the electric actuator and damage the electric actuator.

Japanese Unexamined Patent Publication No. 2018-21575

The present invention has been conceived under the above circumstances, and in a structure in which an electric actuator for an electric parking brake is provided in a posture of protruding outward in the radial direction of the drum brake, the present invention is applied to the inner peripheral surface of the wheel. The main task is to provide a drum brake structure suitable for preventing inconvenience caused by deposits.

In order to solve the above problems, the following technical means are adopted in the present invention.

The drum brake structure provided by the first aspect of the present invention is the above-mentioned drum brake structure in which the electric actuator for the electric parking brake is provided on the back plate of the drum brake in a posture of protruding outward in the radial direction of the drum brake. In the annular space between the virtual circle around the axle passing through the tip of the electric actuator farthest from the axle and the inner peripheral surface of the wheel facing the tip of the electric actuator, the stationary member of the drum brake is used. It is characterized in that the attached protective member is arranged.

In a preferred embodiment, the protective member is arranged outside the electric actuator in the vehicle width direction and at a position overlapping the electric actuator when viewed in the vehicle width direction.

The drum brake structure provided by the second aspect of the present invention is a drum brake structure including a protective member attached to a stationary member of the drum brake, and the protective member is fixed to the stationary member and described above. A mounting portion having a first width dimension in the circumferential direction of the drum brake and an extension extending outward in the radial direction of the drum brake and having a tip edge located between the outer peripheral portion of the drum brake and the inner peripheral surface of the wheel. A second portion having a portion and an easily deformable portion connected to both the mounting portion and the extending portion, and the easily deformable portion is smaller than the first width dimension in the circumferential direction of the drum brake. The extension portion has a width dimension of the above, and is characterized in that the extension portion is biased toward the rear side in the rotation direction of the wheel as it goes outward in the radial direction of the drum brake.

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

It is a top view which shows the 1st Embodiment of the drum brake structure which concerns on this invention. FIG. 5 is a cross-sectional view taken along the line II-II of FIG. 1 with the internal structure omitted. It is a side view which looked at the drum brake structure shown in FIG. 1 from the inside in the vehicle width direction. A modified example of the drum brake structure shown in FIG. 1 is shown, and is the same plan view as in FIG. Another modification of the drum brake structure shown in FIG. 1 is shown, and is the same plan view as in FIG. A second embodiment of the drum brake structure according to the present invention is shown, and is a side view seen from the inside in the vehicle width direction as in FIG. FIG. 6 is a cross-sectional view taken along the line VII-VII of FIG. 6 in which the internal structure is omitted. A modified example of the drum brake structure shown in FIG. 6 is shown, and is a side view similar to that of FIG.

1 to 3 show a first embodiment of the drum brake structure according to the present invention. The drum brake structure A10 of the present embodiment is configured by equipping the drum brake 1 with an electric parking brake, and includes an electric actuator 2 for the electric parking brake and a protective member 3.

The drum brake 1 includes a substantially disk-shaped back plate 11 fixed to the vehicle body side, and a drum 12 attached to the rotating axle side. Although detailed illustration will be omitted, the drum brake 1 has a well-known configuration, and a pair of shoes that can rotate around an anchor portion provided at the lower part of the back plate 11 are assembled to the back plate 11. Has been done. When the brake is applied, the pair of shoes are pressed against the inner peripheral surface of the drum 12 to generate a braking force, and when the brake is released, the pair of shoes are separated from the inner peripheral surface of the drum 12 and no braking force is generated. It becomes.

The back plate 11 is also assembled with a lever (not shown) operated by an electric actuator 2 for an electric parking brake. The lever is connected to a cable (all not shown) that is pushed and pulled through a screw mechanism by driving the electric actuator 2. The lever is also linked to the shoe, and it is possible to switch between a state in which the brake is applied and a state in which the brake is released by the operation of the electric actuator 2. The electric parking brake is maintained in a state in which the brake is applied or a state in which the brake is released even when the drive of the electric actuator 2 is stopped due to the friction of the screw mechanism. In each drawing, the uneven shape of the side surface of the back plate 11 is omitted and shown in a simplified manner.

The electric actuator 2 is supported by the back plate 11 and is arranged inside the vehicle width direction (upper side in the drawing in FIG. 1 and right side in the drawing in FIG. 2) with respect to the back plate 11. The electric actuator 2 is provided in a posture of intersecting the vehicle width direction and projecting outward in the radial direction of the drum brake 1 in order to secure a wide interior width of the vehicle. In the present embodiment, the electric actuator 2 is arranged above the axle, and the tip portion 2a of the electric actuator 2 is at the highest position.

The electric actuator 2 has, for example, a pedestal 21 attached to the back plate 11 and a case 22 attached to the pedestal 21 by bolting or the like, and a motor and a screw mechanism (not shown) are housed in the case 22. Will be done. The pedestal 21 is made of die-cast aluminum, for example, and the case 22 is made of a resin having electrical insulation. In each figure, the electric actuator 2 is shown in a simplified manner.

The protective member 3 is for protecting the electric actuator 2. Although details will be described later, the protective member 3 protects the electric actuator 2 from deposits adhering to the inner peripheral surface 40 of the wheel 4 (see FIG. 2) as the vehicle travels.

The protective member 3 is attached to a stationary member of the drum brake 1. Examples of the stationary member of the drum brake 1 include a back plate 11 and a pedestal 21 of an electric actuator 2 fixed to the back plate 11. The protective member 3 is preferably made of metal from the viewpoint of ensuring a predetermined strength. In the present embodiment, the protective member 3 is fixed to the back plate 11 by appropriate means such as welding or bolting.

The protective member 3 is arranged in the annular space S1 between the tip end portion 2a of the electric actuator 2 and the inner peripheral surface 40 of the wheel 4. More specifically, the annular space S1 includes a virtual circle C1 passing through the tip portion 2a farthest from the axle 5 in the electric actuator 2, and an inner peripheral surface of the inner peripheral surface 40 of the wheel 4 facing the tip portion 2a. It is a spatial area between 40a and 40a. The annular space S1 shown in the drawing schematically shows the annular space referred to in the present invention. At least a part of the protective member 3 exists in the annular space S1.

In the present embodiment, the protective member 3 is arranged at a position corresponding to the electric actuator 2 in the circumferential direction of the axle 5. More specifically, as can be understood from FIGS. 1 to 3, the protective member 3 is outside the electric actuator 2 in the vehicle width direction (lower side in the drawing in FIG. 1 and left side in the drawing in FIG. 2). , It is arranged at a position where it overlaps with the electric actuator 2 when viewed in the vehicle width direction, and a part of the protective member 3 is present at that position. Further, in the present embodiment, a part of the protective member 3 is arranged above the electric actuator 2 at a position where it overlaps with the electric actuator 2 when viewed in the vertical direction.

In the present embodiment, as can be understood from FIGS. 1 to 3, the protective member 3 is appropriately curved or bent to increase the rigidity. More specifically, the protective member 3 is bent so that the outer side in the radial direction is convex in the vertical cross section in the vehicle width direction. Further, as is clearly shown in FIG. 2, the protective member 3 is inward in the vehicle width direction corresponding to the diameter of the inner peripheral surface 40a of the wheel 4 increasing toward the inside in the vehicle width direction (right side in the figure). It is inclined so that it is located radially outward as it goes toward it. The tip 3a of the protective member 3 is bent so as to surround the tip 2a of the electric actuator 2.

Next, the operation of this embodiment will be described.

In the drum brake structure A10 of the present embodiment, the electric actuator 2 for the electric parking brake is provided on the back plate 11 in a posture of protruding outward in the radial direction of the drum brake 1, and the protective member 3 for protecting the electric actuator 2 is provided. Is placed. The protective member 3 has a part of the protective member 3 in the annular space S1 between the virtual circle C1 passing through the tip portion 2a of the electric actuator 2 and the inner peripheral surface 40a facing the tip portion 2a in the wheel 4. Arranged to do.

As the vehicle travels, snow or mud may adhere to and accumulate on the inner peripheral surface 40 of the wheel 4. In the electric actuator 2 having a posture of projecting outward in the radial direction, the gap between the tip portion 2a of the electric actuator 2 and the inner peripheral surface 40a of the wheel 4 facing the tip portion 2a is relatively small. According to the present embodiment, since the protective member 3 is arranged in the annular space S1, the deposits adhering to the inner peripheral surface 40a of the wheel 4 come into contact with the protective member 3 before interfering with the electric actuator 2. Is scraped off. Therefore, damage to the electric actuator 2 can be prevented.

When the wheel 4 is attached to the vehicle, the wheel 4 is made to enter from the outside (left side in the figure in FIG. 2) to the inside (right side in the figure) in the vehicle width direction. In the present embodiment, the protective member 3 is arranged outside the electric actuator 2 in the vehicle width direction (left side in the drawing in FIG. 2) and at a position overlapping the electric actuator 2 when viewed in the vehicle width direction. According to such a configuration, even if the wheel 4 is displaced when the wheel 4 is attached, the wheel 4 hits the protective member 3 before the side surface of the electric actuator 2, so that the electric actuator 2 can be prevented from being damaged. Can be done.

In the present embodiment, a part of the protective member 3 is arranged above the electric actuator 2 at a position where it overlaps with the electric actuator 2 when viewed in the vertical direction. According to such a configuration, even if the wheel 4 falls when the wheel 4 is attached or detached, the wheel 4 hits the protective member 3 before the electric actuator 2. Therefore, the above configuration is more preferable in preventing damage to the electric actuator 2.

In the above drum brake structure A10, the case where the protective member 3 is attached to the back plate 11 has been described, but the attachment mode of the protective member 3 is not limited to this. 4 and 5 show a modified example of the drum brake structure A10 based on the first embodiment. For example, in the drum brake structure A11 shown in FIG. 4, the protective member 3 is attached to the pedestal 21 of the electric actuator 2 as shown by a virtual line. Further, in the drum brake structure A12 shown in FIG. 5, the protective member 3 is attached in an arch shape straddling the pedestal 21 and the back plate 11. Although the illustration will be omitted, the protective member 3 may be integrally formed with the stationary member of the drum brake 1.

6 and 7 show a second embodiment of the drum brake structure according to the present invention. In these figures, the same or similar elements as those in the above embodiment are designated by the same reference numerals as those in the above embodiment, and the description thereof will be omitted as appropriate.

In the drum brake structure A20 of the present embodiment, the configuration of the protective member 3 is mainly different from that of the above embodiment. In the drum brake structure A20, the protective member 3 includes a mounting portion 31, a deformable portion 32, and an extending portion 33. The material of the protective member 3 is made of metal as in the case of the first embodiment.

The mounting portion 31 is fixed to the back plate 11 (stationary member) by appropriate means such as welding or bolt fastening. As shown in FIG. 6, the mounting portion 31 has a predetermined length along the radial direction of the drum brake 1. The mounting portion 31 has a predetermined width dimension t1 in the circumferential direction of the drum brake 1.

The easily deformable portion 32 is a portion that is easily elastically deformed as compared with other portions. The easily deformable portion 32 is located between the mounting portion 31 and the extending portion 33, and is connected to both the mounting portion 31 and the extending portion 33. As shown in FIG. 6, in the easily deformable portion 32, a recess 321 is formed on the front side in the rotation direction N1 of the wheel 4. As a result, the easily deformable portion 32 has a width dimension t2 in the circumferential direction of the drum brake 1 smaller than the width dimension t1 in the mounting portion 31 described above.

The extending portion 33 extends outward in the radial direction of the drum brake 1. Specifically, as shown in FIG. 6, the extending portion 33 is biased toward the rear side of the rotation direction N1 of the wheel 4 toward the radial outer side of the drum brake 1, and is bent with respect to the mounting portion 31. And extend. As shown in FIGS. 6 and 7, the tip edge 331 of the extending portion 33 is located between the outer peripheral portion of the drum brake 1 and the inner peripheral surface 40 of the wheel 4. As shown in FIG. 6, the tip edge 331 of the extending portion 33 substantially follows the circumferential direction of the drum brake 1. The tip edge 331 and the inner peripheral surface 40 of the wheel 4 are separated from each other by a substantially constant gap t3.

As shown in FIG. 7, in the present embodiment, the protective member 3 is appropriately curved or bent to increase the rigidity. The protective member 3 is inclined so as to be located on the outer side in the radial direction toward the inner side in the vehicle width direction. The protective member 3 (extending portion 33) is arranged in the above-mentioned annular space S1.

Next, the operation of this embodiment will be described.

In the drum brake structure A20 of the present embodiment, the protective member 3 has a mounting portion 31, a deformable portion 32, and an extending portion 33. The extending portion 33 extends radially outward of the drum brake 1, and the tip edge 331 of the extending portion 33 is between the outer peripheral portion of the drum brake 1 and the inner peripheral surface 40 of the wheel 4 (annular in the present embodiment). It is located in space S1). According to such a configuration, the deposits formed by snow and mud adhering to the inner peripheral surface 40 of the wheel 4 due to the traveling of the vehicle are protected by the protective member 3 (extending portion 33) before interfering with the electric actuator 2. ) Is contacted and scraped off. Therefore, damage to the electric actuator 2 can be prevented.

A recess 321 is formed in the easily deformable portion 32, and the width dimension t2 of the easily deformable portion 32 is smaller than the width dimension t1 of the mounting portion 31. Further, the extending portion 33 is biased toward the rear side in the rotation direction N1 of the wheel 4 as it goes outward in the radial direction of the drum brake 1. According to such a configuration, when the deposits adhering to the inner peripheral surface 40 come into contact with the tip edge 331 of the extending portion 33 as the wheel 4 rotates in the rotation direction N1, the easily deformable portion 32 elastically deforms. .. With the elastic deformation of the easily deformable portion 32, the extending portion 33 is displaced so as to rotate forward in the rotation direction N1 about the easily deformable portion 32 (displacement center P1 shown in FIG. 6). Here, as described above, as the extension portion 33 extends outward in the radial direction of the drum brake 1, the extension portion 33 is displaced toward the rear side in the rotation direction N1 of the wheel 4, so that the tip edge 331 of the extension portion 33 is shown in FIG. As shown by the virtual line, the wheel 4 is displaced so as to approach the inner peripheral surface 40 of the wheel 4. As a result, the gap t4 between the tip edge 331 of the extending portion 33 and the inner peripheral surface 40 of the wheel 4 becomes smaller than the gap t3 before elastic deformation, and the deposits adhering to the wheel 4 can be sufficiently scraped off. Is.

Further, the extending portion 33 is restored to the original position after scraping off the deposit, and the gap t3 between the tip edge 331 and the inner peripheral surface 40 of the wheel 4 is larger than the gap t4 at the time of elastic deformation. growing. Therefore, it is avoided that the extending portion 33 (protective member 3) repeatedly comes into contact with the sediment for a while until the sediment grows. Therefore, the durability of the protective member 3 is improved.

FIG. 8 shows a modified example of the drum brake structure A20 based on the second embodiment. In the drum brake structure A21 shown in the figure, the protective member 3 has a pair of easily deformable portions 32 and a pair of extending portions 33 extending from the mounting portion 31 in a bifurcated manner. The easily deformable portion 32 and the extending portion 33 located on the left side of the drawing play a role of scraping off the deposits adhering to the wheel 4 when the wheel 4 rotates in the rotation direction N1 during forward movement, for example. The easily deformable portion 32 and the extending portion 33 located on the right side of the drawing scrape off the deposits adhering to the wheel 4 when the wheel 4 rotates in the rotation direction N2 (the direction opposite to the rotation direction N1) when moving backward. Take a role. Although the illustration will be omitted, the protective member 3 may be provided as a separate body so as to function when the wheel 4 rotates in the rotation direction N1 and when the wheel 4 rotates in the rotation direction N2.

In the above-described embodiment (drum brake structures A20 and A21) of the protective member 3 having the mounting portion 31, the easily deformable portion 32, and the extending portion 33, the electric actuator 2 is provided, but the present invention has a configuration. Not limited to this. A drum brake structure including a protective member having a mounting portion, a deformable portion, and an extending portion may be configured not to include an electric actuator.

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.

A10, A11, A12, A20, A21 Drum brake structure C1 Virtual circle N1, N2 Rotation direction P1 Displacement center S1 Circular space t1 Width dimension (first width dimension)
t2 width dimension (second width dimension)
t3, t4 Gap 1 Drum brake 11 Back plate 12 Drum 2 Electric actuator 2a Tip 21 Pedestal 22 Case 3 Protective member 3a Tip 31 Mounting 32 Easy-to-deform section 321 Recess 33 Extension 331 Tip edge 4 Wheel 40 Inner peripheral surface 40a Inner peripheral surface (Wheel inner peripheral surface facing the tip of the electric actuator)
5 axles

Claims (1)

It is a drum brake structure with a protective member attached to the stationary member of the drum brake.
The protective member is fixed to the stationary member and has a mounting portion having a first width dimension in the circumferential direction of the drum brake and extending outward in the radial direction of the drum brake, and the tip edge is an outer peripheral portion of the drum brake. It has an extension portion located between the wheel and the inner peripheral surface of the wheel, and a deformable portion connected to both the mounting portion and the extension portion.
The easily deformable portion has a second width dimension that is smaller than the first width dimension in the circumferential direction of the drum brake.
The extension portion is a drum brake structure characterized in that the extension portion deviates toward the rear side in the rotation direction of the wheel as it goes outward in the radial direction of the drum brake.

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