JPH11280803A - Drum brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake which can restrain the occurrence of a brake judder caused by the deformation of the slide surface of the brake drum braking, and which can reduce a vibration mode of a brake drum that causes brake noise, thereby making it possible to restrain brake noise. SOLUTION: In a drum brake composed of a hub rotatably attached to an axle of a vehicle, a brake drum 1 fixed to the hub, a backing plate fixed to the axle, a brake shoe 2 fixed to the backing plate and a brake wheel cylinder 4 arranged in the backing plate and pressing the brake shoe 2 against the brake drum 1, annular beads 13 are formed on the hub attaching surface 15 of the brake drum 1 on the outer peripheral side of the hub attaching part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum type brake (drum brake) used for a braking device,
In particular, it relates to a brake drum and a hub for mounting the brake drum on an axle, which suppresses the occurrence of brake judder due to distortion of the sliding surface of the brake drum during braking, and furthermore, the vibration of the brake drum which causes brake squeal. The number of modes is reduced, and as a result, the occurrence of squeal is reduced.

[0002]

2. Description of the Related Art As a conventional general drum brake structure, there is one shown in FIGS.
No. 633). That is, the brake drum 01 is formed in a substantially cylindrical shape. A pair of brake shoes 02 are disposed in the brake drum 01 so as to face each other, and the brake shoes 02 are supported on a backing plate fixed to a vehicle body (not shown).
A brake lining 03 formed of a material having frictional performance is attached to the outer peripheral surface of the brake shoe 2, and the brake shoe 02 is expanded by a brake wheel cylinder 04 fixed to a backing plate during braking. The brake lining 03 is formed so as to contact and press the sliding surface 06 of the brake drum 01 to obtain a braking force. In addition, 05 is a return spring, 07 is a hub bolt hole, and 012 is an axle.

The brake drum 01 is connected to a hub 08
The hole provided at the center of the side wall surface 014 provided with the hub mounting surface 015 has a fitting structure for aligning the axial center when the hub 08 is mounted. Further, a hub bolt 010 that penetrates the brake drum 01 is attached to the hub 08, and the hub bolt 010,
The road wheel 09 is mounted by the wheel nut 011.

[0004]

As shown in FIG. 8, since the flatness of the hub mounting surface 015 of the brake drum 01 and the flatness of the mating surface on the hub 08 side are slightly different depending on the processing accuracy, the hub bolt 010 is mounted when the road wheel 09 is mounted. Is tightened, the hub bolt hole 07 of the brake drum 01 is deformed in the axial direction. As a result, the side wall surface 014 is distorted, and the sliding surface 06 is distorted due to this effect as shown in FIGS.
As a result, the roundness of the sliding surface 06 decreases, and the force with which the brake wheel cylinder 04 presses the sliding surface 06 of the brake drum 01 via the brake shoe 02 and the brake lining 03 changes. For this reason, a change in the braking torque occurs and vehicle vibration occurs. This is a phenomenon commonly referred to as brake judder, and this phenomenon causes discomfort to the occupant. To reduce this brake judder,
It is necessary to reduce the roundness reduction margin, and it is effective to absorb the deformation of the brake drum 01 due to the fastening of the hub bolt 010 only by the side wall surface 014. To this end, the strength of the side wall surface 014 is guaranteed. It is said that it is desirable to reduce the rigidity.

An example in which the brake judder is reduced is a technique described in Japanese Utility Model Laid-Open Publication No. 61-146633.
This was achieved by partially changing the thickness of the side wall surface 014 of the brake drum 01 to concentrate the distortion of the brake drum 01 due to the fastening of the hub bolt 010 to the side wall surface 014, thereby suppressing deformation of the sliding surface 06. Things. Also,
In this type of drum brake, the frictional vibration between the sliding surface 06 of the brake drum 01 and the brake lining 03 causes the frictional vibration generated on the sliding surface 06 to vibrate the brake drum 01 during braking, and
As a result of exciting the natural vibration of the vehicle, an unpleasant so-called brake squeal is generated.

Research by the inventor has confirmed that the occurrence of a brake squeal that causes discomfort to the occupant is caused by the vibration mode of the brake drum in which the side wall surface 014 is deformed in the drum brake as shown in FIG. Was done. This is a vibration mode in which the rigidity of the side wall surface 014 causes deformation such that distortion is accumulated in this portion. In order to suppress this vibration mode, it is necessary to increase the rigidity of the side wall surface 014. However, as described above, since it is necessary to reduce the rigidity of the side wall surface 014 in order to suppress the brake judder, there is a problem that it is difficult to achieve both the brake squeal and the judder performance. In view of the above, an object of the present invention is to solve the above problem by suppressing both brake squeal and judder by optimizing the distribution of rigidity of the side wall surface of the brake drum.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, an invention according to claim 1 is provided with a hub fixed to an axle of a vehicle axle so as to be rotatable in an axle rotation direction, and a hub fixed to the hub. A drum brake comprising: a brake drum; a backing plate fixed to the axle; a brake shoe disposed on the backing plate; and an actuator disposed on the backing plate and pressing the brake shoe against the brake drum. An annular projection is formed on the hub mounting surface of the brake drum and on the outer peripheral side of the hub mounting position. According to a second aspect of the present invention, in the drum brake according to the first aspect, an annular groove is provided on an inner peripheral side of the protrusion on the hub mounting surface. According to a third aspect of the present invention, in the drum brake according to the first or second aspect, on the hub mounting surface, the thickness on the inner peripheral side from the protrusion is smaller than the thickness on the outer peripheral side. I do. According to a fourth aspect of the present invention, in the drum brake according to any one of the first to third aspects, a fitting structure is formed by the projection and the hub.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIGS. 1 and 2 show a first embodiment of the present invention. Axle 12 for vehicle axle
A hub 8 rotatably fixed to the axle rotation direction, a brake drum 1 fixed to the hub 8, a backing plate fixed to the axle, a brake shoe 2 arranged on the backing plate, A brake wheel cylinder 4 that is disposed on a backing plate and presses the brake shoe 2 against the brake drum 1. A hub mounting surface 15 of the brake drum 1 and an outer periphery from a hub mounting position in the drum brake. This is a drum brake provided with an annular projection 13 on the side.

In this embodiment, as shown in FIGS. 1 and 2, the brake drum 1 is formed in a substantially cylindrical shape, and a pair of brake shoes 2 in the brake drum 1 are arranged to face each other. The brake shoe 2 is supported on a backing plate fixed to a vehicle body (not shown), and a brake lining 3 formed of a material having frictional performance is attached to an outer peripheral surface of the brake shoe 2.
During braking, the brake shoe 2 is expanded by a brake wheel cylinder 4 fixed to a backing plate, and the brake lining 3 attached to the outer peripheral surface of the brake shoe 2 is pressed against the sliding surface 6 of the brake drum 1 to obtain a braking force. It was formed as follows. 5 is a return spring, and 7 is a hub bolt hole.

Next, the operation of the first embodiment will be described. The flatness of the hub mounting surface 15 of the brake drum 1 and the flatness of the hub side surface slightly differ depending on the processing accuracy. When the hub bolt 10 is fastened when the road wheel 9 is mounted, the hub bolt 10 of the brake drum 1 is deformed in the axial direction. At this time, the side wall surface 1
The projection 13 provided on the base 4 increases the rigidity of this portion, so that the inner peripheral side having lower rigidity than the projection 13 is easily distorted, and the distortion on the outer peripheral side than the projection 13 is suppressed. Therefore, the roundness of the sliding surface 6 does not decrease, the force pressing the sliding surface 6 becomes constant, and the braking torque does not change.
The occurrence of brake judder is suppressed.

The projections 13 act as rigidity against the vibration modes of the brake drum 1 in which the side wall surface 14 is deformed, and the number of modes in the audible range where raising the resonance frequency of these modes and brake squeal become problems. Reduction is achieved,
As a result, brake squeal is suppressed.

<Second Embodiment> FIG. 3 is a diagram showing a second embodiment corresponding to the second aspect of the present invention. The second embodiment is different from the first embodiment in that the protrusions 13 on the side wall surface 14 are different from the first embodiment.
This is a drum brake provided with an annular groove on the inner peripheral side.

Next, the operation of the second embodiment will be described. In the second embodiment, as shown in FIG. 3, an annular groove is provided on the inner peripheral side of the projection 13 with respect to the first embodiment, so that the rigidity of the portion is reduced. Because the difference in rigidity between the inner and outer sides of the
The distortion of the outer peripheral portion when distortion occurs on the inner peripheral side can be suppressed smaller than that in the first embodiment. Therefore, the occurrence of brake judder is more effectively suppressed than in the first embodiment. Further, as described in the first embodiment, the protrusions 13 function as rigidity with respect to the vibration modes of the brake drum 1 in which the side wall surface 14 is deformed, and increase in the resonance frequency of these modes and brake squeal become problems. The number of modes in the audible range is reduced, and as a result, brake squeal is suppressed.

<Third Embodiment> FIG. 4 is a diagram showing a third embodiment corresponding to the third aspect of the present invention. The fourth embodiment is based on the second embodiment, and is a drum brake in which the thickness on the inner peripheral side from the projection 13 is smaller than the thickness on the outer peripheral side.

Next, the operation of the third embodiment will be described. In the third embodiment, as shown in FIG. 4, based on the second embodiment, the thickness of the inner peripheral side of the protrusion 13 is made smaller than the thickness of the outer peripheral side thereof. Since the difference in rigidity between the outer peripheral side and the inner peripheral side is further increased, the distortion of the outer peripheral portion when distortion occurs on the inner peripheral side can be suppressed smaller than in the second embodiment. Therefore, the occurrence of brake judder is suppressed more effectively than in the second embodiment.

<Embodiment 4> FIG. 5 is a view showing an embodiment 4 corresponding to the fourth aspect of the present invention. The fourth embodiment is different from the first embodiment in that the center of the shaft is aligned with the hub mounting surface 15 of the brake drum 1 and the protrusion 13 annularly provided on the outer peripheral side from the hub mounting position and the hub side surface. Drum brake formed with a fitting structure.

Next, the operation of the fourth embodiment will be described. In the fourth embodiment, as shown in FIG. 5, the fitting structure using the protrusion 13 provided on the brake drum side wall surface 14 makes the rigidity of the protrusion 13 due to the restraint with the hub 8 by the fitting. It can be higher. For this reason, even in the case where the strength on the inner peripheral side cannot be reduced more than the protrusion 13, it is possible to increase the difference in rigidity with the outer peripheral side, and distortion occurs on the inner peripheral side. Even in this case, distortion on the outer peripheral side can be suppressed.
Therefore, the roundness of the sliding surface 6 does not decrease, the force pressing the sliding surface 6 becomes constant, and no change in the braking torque occurs, so that the occurrence of brake judder is suppressed. In addition, the protrusion 13 provided on the side wall surface 14 and the fitting structure of the protrusion 13 serve as rigidity against the vibration modes of the brake drum 1 in which the side wall surface 14 is deformed, and increase in the resonance frequency and brake squeal in these modes are problematic. Thus, the number of modes in the audible range is reduced, and as a result, brake squeal is suppressed.

[0019]

As described above, in the drum brake of the present invention, an annular projection is formed on the hub mounting surface of the brake drum and on the outer peripheral side of the hub mounting position. Since the distortion on the outer peripheral side than the portion is suppressed and the braking torque does not change, the effect of suppressing the occurrence of brake judder can be obtained. In addition, the resonance frequency of the vibration mode of the brake drum is increased, and the number of modes in the audible range is reduced, so that the effect of suppressing brake noise can be obtained. In the drum brake according to the second or third aspect, an annular groove is provided on the inner peripheral side of the projection, or the thickness of the inner peripheral side is made thinner than the outer peripheral side when viewed from the projection. Thus, it is possible to more effectively suppress the occurrence of brake judder and brake squeal. In the drum brake according to claim 4,
By forming the fitting structure between the projection and the hub, the rigidity of the projection can be further increased, and even in the case where the rigidity on the inner circumference side cannot be reduced than the projection, the outer circumference can be reduced. Since it is possible to increase the difference in rigidity with the side, it is possible to obtain the effect that the occurrence of brake judder and brake squeal can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a brake drum structure according to a first embodiment.

FIG. 2 is a sectional view of a brake drum hub according to the first embodiment.

FIG. 3 is a sectional view of a brake drum hub according to a second embodiment.

FIG. 4 is a sectional view of a brake drum hub according to a third embodiment.

FIG. 5 is a sectional view of a brake drum hub according to a fourth embodiment.

FIG. 6 is a diagram showing a general drum brake structure.

FIG. 7 is a cross-sectional view of a general brake drum hub road wheel.

FIG. 8 is a diagram illustrating an example of a deviation in flatness of a hub mounting surface.

FIG. 9 is a diagram illustrating an example of distortion of a sliding surface.

FIG. 10 is a diagram illustrating an example of distortion of a sliding surface.

FIG. 11 is a diagram illustrating a brake drum vibration mode that causes squeal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake drum 2 Brake shoe 3 Brake lining 4 Brake wheel cylinder 5 Return spring 6 Sliding surface 7 Hub bolt hole 8 Hub 9 Load wheel 10 Hub bolt 11 Wheel nut 12 Axle 13 Projection 14 Side wall surface 15 Hub mounting surface

Claims (4)

[Claims] 1. A hub fixed to an axle of a vehicle axle so as to be rotatable in an axle rotation direction, a brake drum fixed to the hub, a backing plate fixed to the axle, and disposed on the backing plate. A brake shoe, and an actuator disposed on the backing plate and pressing the brake shoe against the brake drum. A drum brake, comprising: a hub mounting surface of the brake drum, and an outer peripheral side of a hub mounting position. A drum brake, wherein an annular projection is formed. 2. The drum brake according to claim 1, wherein an annular groove is provided on an inner peripheral side of the protrusion on the hub mounting surface. 3. The drum brake according to claim 1, wherein on the hub mounting surface, the thickness on the inner peripheral side from the projection is smaller than the thickness on the outer peripheral side. 4. The drum brake according to claim 1, wherein a fitting structure is formed by the projection and the hub.