GB2308626A

GB2308626A - A drum brake for an automotive vehicle

Info

Publication number: GB2308626A
Application number: GB9626760A
Authority: GB
Inventors: Yeong Bin Kwon
Original assignee: Mando Machinery Corp
Current assignee: Mando Machinery Corp
Priority date: 1995-12-27
Filing date: 1996-12-23
Publication date: 1997-07-02
Also published as: KR970046048A; KR0163226B1; GB9626760D0; JPH09222141A

Description

DRUM BRAKE FOR AN AUTOMOTIVE VEHICLE The present invention relates to a drum brake for an automotive vehicle. More particularly, it relates to a drum brake for an automotive vehicle in which a brake shoe has a plurality of protrusions formed its rim, thereby increasing the flexural rigidity of the brake shoe preventing noise and facilitating even wear Brakes are used to decelerate or stop an automotive vehicle.

As the vehicle decelerates, kinetic energy is, through friction, changed into heat energy and then dissipated. There are disc and drum type brakes. The drum brake consists of a rotating cylindrical drum secured to the automobile's wheel to which pressure is applied by a shoe disposed in the drum or a band disposed around the drum, thereby stopping a vehicle.

FIGS. 2 and 3 depict the structure of a conventional internal-expanding drum brake. The brake consists of a drum 51 secured to a wheel ( not shown ) and brake shoes 52 which lie inside the drum 51. One of each brake shoe 52 is hingedly secured to a backing plate or brake shield 30 by an anchor block 53. The other end of each brake shoe 52 is coupled with a wheel cylinder 40. A lining 54 is bonded or riveted onto the surfaces of the shoes 52. A wheel cylinder 40 has a pair of cylinders (not shown) in a housing 41, by which pressure is generated to apply the shoes 52 to the drum 51. The shoe 52 comprises a rim 52b and a web 52a formed tangent to the inside of the rim 52b. A return spring 55 is disposed adjacent to the wheel cylinder 40, each end of which is coupled with a web 52a.The vector of the force generated by the return spring 55 is opposite but less than that generated by cylinder 40, thereby maintaining a gap between the lining 54 and the drum 51 when the wheel cylinder 40 is not applying its force.

When a brake pedal 10 is depressed, a piston in a master cylinder 20 is moved to compress brake fluid. The compressed fluid forces into the wheel cylinder 40 to press the brake shoes 52 outward against the brake drum 51. The lining 54 decelerates the rotating drum 51 by applying friction force.

In the conventinal drum brake, the brake shoe is comprised of the T type web 52a integrally formed on the inside of the rim 52b. In FIG. 4, the web 52a is pushing the rim 52b outward by the action of the wheel cylinder 40. When the lining 54 contacts the inside of the drum 51, the resulting friction decelerates,the drum 51. The relatively narrow rim 52a in cross-section pushes the relatively wide rim 52b in its central portion, producing an uneven distribution of force. That is, the central portion of the lining 54 connected to the rim 52b, which receives maximal force, develops maximal friction with the drum 51. In contrast, the peripheral portion of the rim 52b receives less force and thereby bends inward.

Consequently, the deformed portions, each end of the lining 54, does not contact the inside of the drum 51, resulting in uneven wear of the lining 54 . This decreases the braking efficiency of the drum brake, causing safty concerns.

The present invention eliminates the above-mentioned problems of the conventional art by introducing a modified drum brake.

The objective of the present invention is to provide a drum brake by which even pressure is applied by the lining to the inside surface of the drum, thereby promoting even wear and decreased noise.

In order to achieve the above objective and its advantages, and in accordance with the purpose of the present invention as embodied and broadly described herein, the present invention includes: a drum secured to an automoSbile's wheel; a lining which applies the frictional force to with the inner side of said drum; a brake shoe having a rim, on which said lining is attached; and a deformation preventing means provided on said rim for preventing said shoe's defor mation by facilitating even friction between said lining and said drum.

Further, the deformation preventing means comprises a plurality of protrusions formed on said rim for increasing flexural rigidity.

FIG. 1 is a cross-section view of the drum brake in accordance with the present invention; FIG. 2 is a schematic whole view of a drum brake in accordance with a prior art; FIG. 3 is a cross-section view of the conventional drum brake along with line 3-3 of FIG.2; and FIG. 4 is a cross-section view of the drum brake during braking.

The preferred embodiment of the present invention will now be discussed in detail with reference to FIG. 1.

Hereafter, components which are the same as that of the prior art are designated by the same numerals. Thus, no detailed explanation of these components will be provided.

The present invention's drum brake comprises a drum 51 rotating along the axis of the automobile's wheel and a lining 54 frictionally contacting the drum 51. The drum brake further has a brake shoe 52 and a wheel cylinder 40 which press the brake shoe 52 against the drum 51 with hydraulic pressure. The brake shoe 52 has a rim 52b with a lining 54 on the surface thereof and a web 52a formed at the inside of the rim 52b through which the wheel cylinder 40 acts on the rim 52b.

The rim 52b further has means for preventing its deformation during braking, which is a plurality of protrusions 60. Since the web 52a applies force to the rim 52b toward its center during the brake, the deformation occurs at the peripheral portion of the rim 52b. These protrutions 60 increase the rim 52b', flexural rigidity or deformation resistance against a load (EI/(1- u2), wherein E is young modulus,tris a moment of poisson's ratio.Thus, the lining 54 is bonded on the protrusions 60 formed on the outer surface of the rim 52b and the bonding force increases with the widening of the contact surface, thereby preventing the peol-off of the lining from the rim during the braking The action of the above structure is as follows: As shown in FIGS. 1 and 2, according to the actuation by the wheel cylinder 40, the web 52b pushes the rim 52b having the lining 54 thereon and the lining 54 is fricitionally contacted to the inside of the drum 51. The inventive rim 52b has maximal flexural rigidity so that no deformation is occurred.

Therefore, the lining 54 attached on the outside surface of the rim 52b is evenly contacted with the innersurface of the drum 51, increasing the efficiency of the braking action. Further, because of the uniformal friction there is even wearing of the lining and a reduction of noise generated.

Also, because the bonding force between the ouside surface of the rim 52b and the lining 54 is increased in proportion with the widening of the contacting width, shearing force will not remove the lining.

In summary, the present invention provides protrusions formed on the rim lining to increase flexural rigidity, and the lining is uniformally contacted with the inside surface of the drum, facilitate the wear of the hinged connected with the inside surface of the drum brake.

Claims

WHAT IS CLAIMED:

1. A drum brake for an automotive vehicle comprising: a drum secured to an automotive wheel; a lining which applies frictional force with the inner side of said drum; a brake shoe having a rim, on which said lining is attached; and a deformation preventing means provided on said rim for preventing said shoe's deformation by facilitating even friction between said lining and said drum.

2. A drum brake for an automotive vehicle as set forth in claim 1, wherein said deformation preventing means comprises a plurality of protrusions formed on said rim for increasing flexural rigidity.