JPH0673478U - Rotating drum of duo servo type drum brake - Google Patents

Abstract

(57) [Abstract] [Purpose] A rotating drum of a duo-servo type drum brake capable of suitably preventing the shoe holddown device from being deformed due to the lift of the brake shoe from the backing plate during braking. I will provide a. [Configuration] On the inner peripheral surface of the cylindrical portion 70 of the rotating drum 66,
Side end surface 8 of the shoe rim 20 of the brake shoes 12 and 14
An annular stepped surface 82 is provided to prevent the brake shoes 12, 14 from rising above the backing plate 10 beyond a certain limit based on the contact with the brake shoe 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotary drum of a duo servo type drum brake.

[0002]

[Prior art]

 The shoe rims have arcuate and plate-like shoe rims, respectively, and are arranged on the backing plate at one side end surface in the width direction of the shoe rims, and are expanded with respect to each other while being pressed against the backing plate by the shoe hold down device. A pair of brake shoes that are openably supported, a connecting member that connects one end of the pair of brake shoes to each other, and an anchor member that is fixed on the backing plate between the other ends of the pair of brake shoes. There is known a duo-servo type drum brake having a cylindrical portion and a rotary drum rotatably provided in the cylindrical portion so as to accommodate the pair of brake shoes. In such a duo-servo type drum brake, a pair of brake shoes are expanded and pressed against the inner peripheral surface of the rotating drum to suppress the rotation of the rotating drum, and braking is performed. The braking torque is received by the anchor member, and the braking torque generated in the other brake shoe is received by the anchor member via the connecting member and one of the brake shoes.

[0003]

[Problems to be solved by the device]

 However, in such a duo-servo type drum brake, when the rotational force of the rotary drum during braking is relatively large, the one brake shoe is pressed against the anchor member by the other brake shoe via the connecting member. Then, a relatively large force in the direction of separating the brake shoe from the backing plate acts on the end of the brake shoe on the connecting member side, and the end of the brake shoe on the connecting member side resists the urging force of the shoe hold down device. As a result, there is a case where it floats up relatively large from the backing plate, which may deform the shoe hold down device, for example.

The present invention has been made in view of the above circumstances. The purpose of the present invention is to increase the height of the brake shoe from the backing plate during braking, thereby causing a shoe hold down device or the like. Another object of the present invention is to provide a rotary drum of a duoservo type drum brake capable of suitably preventing the deformation of the drum.

[0005]

[Means for Solving the Problems]

 The gist of the present invention for achieving the above-mentioned object is to have an arc-shaped and plate-shaped shurim, which is arranged on the backing plate at one side end surface in the width direction of the shoe rim and is the shoe. A pair of brake shoes that are supported so as to be able to expand each other while being pressed against the backing plate by a hold down device, a connecting member that connects one end portions of the pair of brake shoes to each other, and the pair of brake shoes. Is a duo-servo type drum brake having an anchor member fixed on the backing plate between the other ends of the pair, and has a cylindrical portion, and the pair of brake shoes is housed in the cylindrical portion. The pair of brake shoes are rotatably provided in a state of being expanded and pressed against the inner peripheral surface of the cylindrical portion. In the rotating drum in which the rotation is further suppressed, the backing plate is formed from the inner peripheral surface of the cylindrical portion and the other side end surface in the width direction of the shoe shoe of the brake shoe accommodated in the cylindrical portion. Protruding toward the inner side of the cylindrical part at a position separated by a certain distance to the opposite side, and rising above a certain limit from the backing plate of the brake shoe due to contact with the other side end surface of the shoe rim. This is due to the provision of an annular contact surface for preventing the above.

[0006]

[Effect of action and device]

 By doing so, even when a relatively large force in the direction of separating from the backing plate acts on the end portion of the brake shoe on the connecting member side during braking when the rotational force of the rotating drum is relatively large, The brake is performed based on the contact between the annular contact surface provided on the inner peripheral surface of the cylindrical portion of the rotating drum so as to project toward the inner peripheral side and the other side end surface in the width direction of the shoe rim of the brake shoe. Since the end of the shoe on the side of the connecting member is prevented from rising above the backing plate beyond a certain limit, it is preferable that the shoe hold-down device is deformed due to the lifting of the brake shoe during braking. Can be prevented.

[0007]

【Example】

 An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a view showing a part of a duoservo type drum brake which is a parking brake dedicated mechanism of the drum-in disc brake. In the figure, a pair of brake shoes 12, 14 having an arc shape as a whole are provided on the backing plate 10 so as to be able to expand each other by shoe hold down devices 16, 18. As shown in FIG. 1 and FIG. 2, the brake shoes 12 and 14 are a strip-shaped shoe rim 20 curved in an arc shape, and a backing plate 10 provided so as to project on the inner peripheral surface of the shoe rim 20. Each of the shoe webs 22 is provided with a plate-shaped shoe web 22 arranged substantially in parallel and a lining 24 fixed to the outer peripheral surface of the shoe 20, and the shoe web 22 is positioned substantially parallel to the plate surface of the backing plate 10. In the state, the shoe rim 20 is arranged on the backing plate 10 at one side end surface 26 in the width direction.

As shown in FIG. 1, the shoe holddown devices 16 and 18 are axially formed of, for example, SWRM3, have a head portion 28 at one end, and a curved portion 30 at an intermediate portion in the longitudinal direction. A compression coil spring 34, and a pair of cups 36 and 38 arranged on both sides of the compression coil spring 34 in the axial direction. In the shoe hold down devices 16 and 18, the shoe hold down pin 32 is swingably attached to the through hole 40 of the backing plate 10 at the other end, and the head 28 side of the shoe hold down pin 32 is a brake shoe 12, 14. Of the shoe web 22 is inserted into a notch 42 formed in the longitudinal middle portion of the shoe web 22 and protrudes from the shoe web 22, and a cup 36, 38 is interposed between the head 28 of the shoe hold down pin 32 and the shoe web 22. The compression coil spring 34 is inserted between the brake shoes 12 and 14 and the backing plate 10 in a pre-loaded state, so that the brake shoes 12 and 14 are expanded against each other while being pressed against the backing plate 10. Support to open. The curved portion 30 of the shoe hold down pin 32 is provided to prevent the parking brake lever 56 from interfering with the shoe hold down pin 32 when the parking brake lever 56, which will be described later, rotates in the braking direction. It was received.

One end portion of the shoe web 22 of the brake shoes 12 and 14 located below in FIG. 2 has both ends of a connecting member 46 having an adjusting wheel 44 and having a variable axial length. Not engaged according to the biasing force of the springs. On the other hand, the other ends of the shoe webs 22 of the brake shoes 12 and 14 are adapted to be brought into contact with the outer peripheral surfaces of anchor pins 48 as anchor members fixed on the backing plate 10, respectively. It is constantly urged toward the anchor pin 48 side by the shoe return springs 52 and 54 which are respectively stretched between the male screw member 50 screwed to the tip surface and the brake shoes 12 and 14.

The shoe web 22 of the one brake shoe 12 is provided with a longitudinal plate-shaped parking brake lever 56 rotatably at one end, and the parking brake lever 56 and the longitudinal intermediate portion of the parking brake lever 56. Struts 58 are stretched between the other brake shoe 14. In FIG. 2, 60 is a parking cable, 62 is a cable guide, and 64 is a shoe lifting prevention plate for preventing the ends of the brake shoes 12, 14 on the anchor pin 48 side from lifting from the backing plate 10. is there.

Further, in FIG. 1, reference numeral 66 is a rotary drum, and 68 is a hub that is rotated together with a drive shaft (not shown) protruding from a central hole (not shown) of the backing plate 10. The rotary drum 66 is cast and formed, and has a bottomed cylindrical shape having a cylindrical portion 70 and a bottom portion 72 provided at one axial end thereof, and the opening of the cylindrical portion 70. The outer peripheral surface of the side end portion is integrally provided with a disc-shaped portion 74 protruding toward the outer peripheral side. The rotary drum 66 is adapted to be fixed to the hub 68 at the bottom portion 72 by a plurality of bolts 76 (only one is shown in FIG. 1) protruding from the hub 68, whereby the cylindrical portion 70 The opening side ends are opposed to each other in a state of being close to the backing plate 10, and the brake shoes 12, 14 are housed in the cylindrical portion 70 thereof with a predetermined gap.

In the duoservo type drum brake configured as described above, the parking cable 60 is pulled in and the parking brake lever 56 is rotated counterclockwise in FIG. 14 is pushed to the outer peripheral side and pressed to the inner peripheral surface of the cylindrical portion 70 of the rotary drum 66, and the brake shoe 12 is pushed to the outer peripheral side by its reaction force and pressed to the inner peripheral surface of the rotary drum 66. And braking is performed. At this time, the brake shoes 12 and 14 are rotated in the circumferential direction of the rotary drum 66 in accordance with the direction of the rotational force acting on the rotary drum 66, and the braking torque generated on the brake shoes 12 and 14 is applied to the brake shoes. It is transmitted to the anchor pin 48 from either one of 12 and 14 and is received by the anchor pin 48. When the rotating force of the rotating drum 66 is relatively large during such braking, a relatively large force in the direction of separating from the backing plate 10 acts on the ends of the brake shoes 12, 14 on the connecting member 46 side. There is a case to do.

On the other hand, the disc-shaped portion 74 provided on the rotary drum 66 constitutes a part of the disc brake mechanism of the drum-in disc brake, and the disc-shaped portion 74 has the disc-shaped portion 74. A caliper (not shown) movably supported in a direction parallel to the axis of the disc-shaped portion 74 is laid across the non-rotating member. As a result, when the caliper is actuated by hydraulic pressure, the disc-shaped portion 74 is clamped via a pair of pads (not shown), and the caliper is controlled. It should be noted that such a disc brake mechanism is not always necessary for understanding the present invention and is well known, so a detailed description thereof will be omitted.

Here, in this embodiment, as shown in FIG. 1, the cylindrical portion 70 of the rotary drum 66 is located on the side of the disc-shaped portion 74 and is arranged on the outer peripheral side of the brake shoes 12, 14. Has a thin portion 78 and a thick portion 80 located on the bottom 72 side, and by making the inner diameter of the thick portion 80 smaller than the inner diameter of the thin portion 78 by a predetermined dimension, An annular stepped surface 82 is formed between the inner peripheral surface and the inner peripheral surface of the thin portion 78. The dimension of the stepped surface 82 in the radial direction of the cylindrical portion 70, that is, the protruding dimension l ₁ from the inner peripheral surface of the thin portion 78 is at least larger than the thickness of the lining 24 when not worn (new), for example, , The thickness of the lining 24 when not worn and the thickness of the shoe rim 20 is slightly larger than the total dimension of about 5 mm to 10 mm, so that the brake shoes 12 on the backing plate 10, The other side end surface 84 of the shoe rim 20 in the width direction of 14 can contact the stepped surface 82 in a direction parallel to the axis of the rotating drum 66. Further, the distance l ₂ between the side end surface 84 of the shoe rim 20 and the stepped surface 82 is a shoe due to the lifting of the brake shoe 12, 14 at the end on the connecting member 46 side from the backing plate 10. Permanent deformation of the bending portion 30 of the hold-down pin 32 in the extension direction can be prevented based on the contact between the side end surface 84 of the shoe rim 20 and the stepped surface 82, and the side end surface 84 of the shoe rim 20 when not braking. In order to reliably prevent contact with the stepped surface 82 and avoid dragging of the brake, for example, shoe holddown devices 16 and 18 are provided in the longitudinal central portions of the brake shoes 12 and 14. If there is, the residual compression amount of the compression coil spring 34 (the difference between the axial length in the state where the brake shoes 12 and 14 are not lifted up and the contact length at the time of maximum compression is For example, set to two times or less (for example, about 5m m~8mm) of about 4 mm). In the present embodiment, the stepped surface 82 constitutes an annular contact surface.

As described above, according to the present embodiment, the stepped surface 82 provided on the inner peripheral surface of the rotary drum 66 at a position separated from the side end surface 84 of the shoe rim 20 of the brake shoes 12, 14 by the distance l _2. Based on the contact between the brake shoe 12 and the side end surface 84 of the shoe rim 20, further lifting of the brake shoes 12 and 14 from the backing plate 10 is prevented, so that the rotating force of the rotating drum 66 is relatively large. Even when a relatively large force in the direction of separating from the backing plate 10 is applied to the ends of the brake shoes 12, 14 on the side of the connecting member 46 during the parking brake braking, the brake shoes 12, 14 are lifted. As a result, it is possible to reliably prevent the curved portion 30 of the shoe hold down pin 32 from being elongated and permanently deformed. As a result, the expansion of the curved portion 30 of the shoe hold down pin 32 causes the cup 36 to interfere with the hub 68 and the like to cause drag of the brake, or the preload of the compression coil spring 34 is significantly reduced. Can be reliably prevented.

Further, according to the present embodiment, the brake shoes 12, 14 are contacted based on the contact between the side end surface 84 of the shoe rim 20 of the brake shoes 12, 14 and the stepped surface 82 of the inner peripheral surface of the rotating drum 66. Since the lifting of 14 from the backing plate 10 over a certain limit is prevented, the deformation of the brake shoes 12, 14 and the connecting member 46 due to the lifting over the certain limit can be preferably prevented.

Further, according to the present embodiment, the stepped surface 82 of the rotary drum 66 can be formed at the time of casting molding of the rotary drum 66, and the above effect can be obtained only by fixing the rotary drum 66 to the hub 68. The advantage is that the number of parts of the duo-servo type drum brake, the number of assembling steps, and the cost are not increased.

Although one embodiment of the present invention has been described above, the present invention can be applied to other aspects.

For example, in the above embodiment, the cylindrical portion 70 of the rotary drum 66 is configured to have the thick portion 80, but it is not always necessary. For example, the thick portion 80 of FIG. The rotating drum 66 may be made lighter by removing the portion located on the outer peripheral side of the dashed line from the annular shape, or the portion located on the outer peripheral side of the thick portion 80 of the thickened portion 80 may be circumferentially defined. The rotary drum 66 may be lightened and the heat dissipation of the rotary drum 66 may be improved by removing them at intervals and forming a large number of fins 86 as shown in FIG.

Further, in the above embodiment, the stepped surface 82 provided on the inner peripheral surface of the cylindrical portion 70 of the rotary drum 66 constitutes the annular contact surface, but this is not always necessary. For example, a discontinuous ring-shaped member is fitted in an annular groove provided at an intermediate portion in a direction parallel to the axis of the inner peripheral surface of the cylindrical portion at a part in the circumferential direction, and the ring-shaped member is provided with a ring on one surface. It is also possible to form the abutment surface.

Further, in the above-described embodiment, the shoe holddown devices 16 and 18 are configured to have the compression coil springs 34, but the shoe holddown device includes a U-shaped leaf spring and a shoe holddown pin. It may be one. In this case, by applying the present invention, not only the deformation of the shoe hold-down pin due to the lift of the brake shoe but also the deformation of the U-shaped leaf spring can be preferably prevented.

Further, in the above-described embodiment, the case where the present invention is applied to the duo-servo type drum brake as the parking brake dedicated mechanism of the drum-in disc brake has been described, but the service brake by the parking brake mechanism and the wheel cylinder is described. Of course, the present invention can be applied to a duo servo type drum brake equipped with a mechanism.

In addition, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is an enlarged view of a main part of a cross section taken along the line I-I in FIG. 2, showing a part of a rotary drum together.

FIG. 2 is a diagram showing an example of a duo-servo type drum brake to which the present invention is applied, in which a rotary drum and the like are removed.

FIG. 3 is a view for explaining another example of the present invention,
It is a figure which shows a part of rotary drum.

[Explanation of sign]

 10: backing plate 12, 14: brake shoe 16, 18: shoe hold down device 20: shoe rim 26, 84: side end surface 46: connecting member 48: anchor pin (anchor member) 66: rotating drum 70: cylindrical member 82: step Attached surface (annular contact surface)

Claims (1)

[Scope of utility model registration request] 1. An arc-shaped and plate-shaped shoe rim, wherein the shoe rim is disposed on the backing plate at one side end surface in the width direction of the shoe rim and is pressed against the backing plate by a shoe hold down device. A pair of brake shoes that are supported so as to be able to expand, a connecting member that connects one end portions of the pair of brake shoes to each other, and an anchor fixed on the backing plate between the other end portions of the pair of brake shoes. A duo-servo type drum brake including a member, wherein the pair of brake shoes is rotatably provided while having a cylindrical portion, and the pair of brake shoes is accommodated in the cylindrical portion. In the rotary drum, the rotation of which is suppressed by being pressed against the inner peripheral surface of the cylindrical portion, And at a position separated from the other side end surface in the width direction of the shoe rim of the brake shoe housed in the cylindrical portion to the side opposite to the backing plate by a predetermined distance, to the inner peripheral side of the cylindrical portion. A duo-servo type drum provided with an annular abutment surface that prevents the brake shoe from being lifted above a certain limit from the backing plate based on the abutment with the other side end surface of the shoe rim. The rotating drum of the brake.