FLANGED SHIM FOR BRAKE SQUEAL ATTENUATION
A brake pad assembly provided for a disc brake apparatus. The brake pad assembly comprises a backing plate having a flat inner face and a flat outer face oriented opposite to the inner face, a friction member fixed to the inner face of the backing plate, and an anti-squeal shim attached to the outer face of the backing plate. The anti-squeal shim includes a flat support plate attached to the outer face of the backing plate and a straight flat flange plate. The support plate of the anti-squeal shim has a peripheral edge including opposite outer and inner edges and opposite side edges. The flange plate is in the form of a flexible cantilever formed integrally with the support plate of the anti-squeal shim and extends away from one of the outer, inner and opposite side edges of the support plate of the anti-squeal shim.
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This Application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application Ser. No. 61/026,521 filed Feb. 6, 2008 by Kappagantu, R., which is hereby incorporated herein by reference in its entirety and to which priority is claimed.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present inventions relates to brake pad assemblies for disc brakes in general and more particularly to a shim structure of a disc brake pad assembly for sound damping brake squeal noise in a disc brake apparatus.
2. Description of the Prior Art
Conventionally, in a disc brake apparatus two opposite brake pad assemblies compress a brake rotor in order to decelerate or stop the rotation of the brake rotor. The typical disc brake pad assembly 1, illustrated in
When the brake piston presses a back face of the backing plate 2 of the disc brake pad assembly 1 inwardly during the braking operation, an inner surface of the friction pad 4 is engaged in frictional, braking contact with the brake rotor of the disc brake apparatus. Such an action creates high operating temperatures of the disc brake apparatus (500 C.° or more) and high specific area pressures (about 1000 kg/cm2) as the brake piston normally has a relatively small cross section. The friction between the brake rotor and the brake pad assembly generates vibration of the elements of the brake pad assembly during braking operation. As a result, unpleasant and often loud braking noise, particularly relatively high pitched and undesired brake “squeal” noise, frequently occurs during the braking operation.
Numerous solutions to the brake noise problem have been proposed, many of which rely on the principle of damping vibrations. One of the most common solutions known in the art is placing of a noise-damping shim 6 (as illustrated in
While known solutions to the brake noise problem, including but not limited to the noise-damping shims discussed above, have proven to be acceptable for various disc brake applications, such devices are nevertheless susceptible to improvements that may enhance their performance, cost and packaging. With this in mind, a need exists to develop improved anti-squeal shims for the disc brake apparatuses that advance the art.
SUMMARY OF THE INVENTIONThe present invention provides an improved brake pad assembly for a disc brake apparatus. The brake pad assembly comprises a backing plate having a flat inner face and a flat outer face oriented opposite to the inner face, a friction member fixed to the inner face of the backing plate, and an anti-squeal shim attached to the outer face of the backing plate. The anti-squeal shim includes a flat support plate attached to the outer face of the backing plate and a straight flat flange plate. The support plate of the anti-squeal shim has a peripheral edge including opposite outer and inner edges and opposite side edges. The flange plate is in the form of a flexible cantilever formed integrally with the support plate and extends away from one of the outer, inner and opposite side edges of the support plate of the anti-squeal shim.
The anti-squeal shim of the brake pad assembly in accordance with the present invention substantially increases stiffness and energy dissipation of the brake pad assembly, and resulting vibration damping during the braking operation of the disc brake apparatus of the vehicle. Consequently, the brake pad assembly in accordance with the present invention allows for significant overall reduction of braking noise.
Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in light of the accompanying drawings, wherein:
The preferred embodiment of the present invention will now be described with the reference to accompanying drawings.
For purposes of the following description, certain terminology is used in the following description for convenience only and is not limiting. The words “top”, “bottom”, “right”, “left”, “lower”, “upper”, “inner” and “outer” designate directions in the drawings to which reference is made. The words “uppermost” and “lowermost” refer to position in a vertical direction relative to a geometric center of the apparatus of the present invention and designated parts thereof. The terminology includes the words above specifically mentioned, derivatives thereof and words of similar import. Additionally, the word “a” as used in the claims means “at least one”.
In view of the structural similarities of the inner and outer brake pad assemblies 20a and 20b, and in the interest of simplicity, the following discussion will use a reference numeral without a letter to designate an entire group of substantially identical structures. For example, the reference numeral 20 will be used when generically referring to the brake pad assemblies 20a and 20b rather than reciting all two reference numerals.
Although, the disc brake apparatus 10 illustrated in
The brake pad assembly 20 further comprises an anti-squeal (sound damping) shim 26 to reduce and/or to eliminate undesired brake squeal noise generated by the brake pad assembly 20 during the braking operation thereof. As illustrated in
The support plate 28 is fixedly attached to an outer face 22b of the backing plate 22 (i.e. the side of the backing plate 22 facing away from the brake rotor 12 when mounted in the disc brake apparatus 10 as shown in
The support plate 28 of the anti-squeal shim 26 has a peripheral edge having four vertices 27a, 27b, 27c and 27d, and including opposite outer and inner edges 32 and 33, respectively, and opposite side edges 34a and 34b. The term “outer peripheral edge of the support plate” as used herein refers to the edge 32 of the support plate 28 disposed closer to an outer peripheral edge 15 of the brake rotor 12 when the brake pad assembly 20 is installed in the disc brake apparatus 10, while the term “inner peripheral edge of the support plate” refers to the edge 33 of the support plate 28 farthest from the outer peripheral edge 15 of the brake rotor 12 when the brake pad assembly 20 is installed in the disc brake apparatus 10. It is to be understood that the term “opposite side edges” refers to the edges 34a and 34b of the support plate 28 disposed between the opposite outer and inner edges 32, 33 thereof. In other words, the outer edge 32 extends between the vertices 27a and 27b, the inner edge 33 extends between the vertices 27c and 27d, and the opposite side edges 34a and 34b extend between the vertices 27a-27c and 27b-27d, respectively.
As further illustrated in
Thus, any edge of the support plate (28, 128 or 228) of the anti-squeal shim (26, 126 or 226), from which the straight flange plate (30, 130 or 230) extends, is in the form of the straight line extending between the corresponding vertices of the peripheral edge of the support plate (28, 128, or 228). Moreover, the anti-squeal shim (26, 126 or 226) according to the present invention may be provided with more than one straight flange plate (30, 130 or 230) extending from any of the outer, inner or side edges of the support plate in any possible combinations. For example, the anti-squeal shim 26 may have two straight flange plates 30 including one extending from the inner edge 33 of the support plate 28 and one extending from the outer edge 32 thereof. In other words, any combination of two, three or four straight flange plates 30 is within the scope of the present invention. However, in any such case, the anti-squeal shim 26 is flanged only when there is little or no interference with the brake piston any part of the disc brake apparatus 10.
Preferably, as illustrated in
As the brake squeal noise is produced by vibration of the brake pad assembly 20 during braking actuation, forming the straight flange plate 30 on the anti-squeal (sound damping) shim 26 has a twofold effect: first, the flange shape changes the stiffness of the brake pad assembly 20, thus altering modal alignment with respect to squeal rotor modes; and second, the straight flange plate 30 increases the energy dissipation and resulting damping at modes of interest. As a result, the brake pad assembly in accordance with the present invention allows for overall reduction of noise from 28% to 6%, as illustrated in
Therefore, the novel anti-squeal shim of the brake pad assembly in accordance with the present invention substantially increases stiffness and energy dissipation of the brake pad assembly, and resulting vibration damping during the braking operation of the disc brake apparatus of the vehicle. Consequently, the brake pad assembly in accordance with the present invention allows for significant overall reduction of braking noise.
The foregoing description of the preferred embodiments of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments disclosed hereinabove were chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated, as long as the principles described herein are followed. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.
Claims
1. A brake pad assembly for a disc brake apparatus, said brake pad assembly comprising:
- a backing plate having an inner face and an outer face oriented opposite to said inner face;
- a friction member fixed to said inner face of said backing plate; and
- an anti-squeal shim attached to said outer face of said backing plate;
- said anti-squeal shim including a support plate attached to said outer face of said backing plate and a straight flat flange plate;
- said support plate of said anti-squeal shim having a peripheral edge including opposite outer and inner edges and opposite side edges;
- said flange plate being in the form of a flexible cantilever formed integrally with said support plate of said anti-squeal shim and extending away from one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim.
2. The brake pad assembly as defined in claim 1, wherein said flange plate extends outwardly from one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim in the direction away from said backing plate.
3. The brake pad assembly as defined in claim 1, wherein both said support plate and said flange plate are formed integrally from a single blank of a shim material.
4. The brake pad assembly as defined in claim 3, wherein said shim material is a multi-layer composite material.
5. The brake pad assembly as defined in claim 4, wherein said multi-layer composite material includes a stainless steel plate coated with a layer of adhesive on one face thereof and with a layer of paint on the other face thereof.
6. The brake pad assembly as defined in claim 1, wherein one of said upper, lower and opposite side edges of said support plate of said anti-squeal shim from which said flange plate extends is formed as a straight line.
7. The brake pad assembly as defined in claim 6, wherein said flange plate of said anti-squeal shim extends along an entire length of one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim.
8. The brake pad assembly as defined in claim 6, wherein said flange portion extends along said inner peripheral edge of said support plate of said anti-squeal shim.
9. The brake pad assembly as defined in claim 6, wherein said flange portion extends along said outer peripheral edge of said support plate of said anti-squeal shim.
10. The brake pad assembly as defined in claim 6, wherein said flange portion extends along one of said opposite side edges of said support plate of said anti-squeal shim.
11. The brake pad assembly as defined in claim 2, wherein vertices of said peripheral edge of said support plate of said anti-squeal shim are located on said outer face of said backing plate within a peripheral edge thereof.
12. A disc brake apparatus comprising:
- a brake support member;
- a brake rotor;
- a brake pad assembly slidably supported by said brake support member so as to be movable over a predetermined distance in the axial direction of said brake rotor;
- a caliper straddling said brake rotor and slidably mounted to said brake support member to allow sliding in the axial direction of the brake rotor, said caliper having a cylinder formed therein; and
- a piston slidably mounted in said cylinder of said caliper to allow sliding in the axial direction of said brake rotor, said piston facing said brake pad assembly at a side thereof remote from said brake rotor;
- said brake pad assembly comprising: a backing plate having a flat inner face facing said brake rotor and a flat outer face oriented opposite to said inner face and facing said piston; a friction member fixed to said inner face of said backing plate; and an anti-squeal shim attached to said outer face of said backing plate; said anti-squeal shim including a flat support plate attached to said outer face of said backing plate and a straight flat flange plate; said support plate of said anti-squeal shim having a peripheral edge including opposite outer and inner edges and opposite side edges; said flange plate being in the form of a flexible cantilever formed integrally with said support plate of said anti-squeal shim and extending away from one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim; said flange portion of said anti-squeal shim spaced from said brake support member, said caliper and said piston.
13. The disc brake apparatus as defined in claim 1, wherein said flange plate extends outwardly from one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim in the direction away from said backing plate.
14. The brake pad assembly as defined in claim 13, wherein both said support plate and said flange plate are formed integrally from a single blank of a shim material.
15. The brake pad assembly as defined in claim 12, wherein one of said upper, lower and opposite side edges of said support plate of said anti-squeal shim from which said flange plate extends is formed as a straight line.
16. The brake pad assembly as defined in claim 15, wherein said flange plate of said anti-squeal shim extends along an entire length of one of said outer, inner and opposite side edges of said support plate of said anti-squeal shim.
17. The brake pad assembly as defined in claim 15, wherein said flange portion extends along said inner peripheral edge of said support plate of said anti-squeal shim.
18. The brake pad assembly as defined in claim 15, wherein said flange portion extends along said outer peripheral edge of said support plate of said anti-squeal shim.
19. The brake pad assembly as defined in claim 15, wherein said flange portion extends along one of said opposite side edges of said support plate of said anti-squeal shim.
20. The brake pad assembly as defined in claim 12, wherein vertices of said peripheral edge of said support plate of said anti-squeal shim are located on said outer face of said backing plate within a peripheral edge thereof.
Type: Application
Filed: Aug 13, 2013
Publication Date: Apr 17, 2014
Applicant: Material Sciences Corporation (Elk Grove Village, IL)
Inventors: Ramana KAPPAGANTU (Canton, MI), Eric DENYS (Ann Arbor, MI)
Application Number: 13/965,784
International Classification: F16D 65/00 (20060101); F16D 55/22 (20060101);