U.S. patent application number 10/103585 was filed with the patent office on 2002-12-19 for vibration damping shim structure.
Invention is credited to Arai, Tadashi, Niwa, Takahiro, Yano, Kunihiko, Yoshihara, Masaki.
Application Number | 20020189910 10/103585 |
Document ID | / |
Family ID | 18952718 |
Filed Date | 2002-12-19 |
United States Patent
Application |
20020189910 |
Kind Code |
A1 |
Yano, Kunihiko ; et
al. |
December 19, 2002 |
Vibration damping shim structure
Abstract
A vibration damping shim structure is provided, which not only
can sufficiently exert vibration damping effect in a wide range of
temperatures, but also can prevent a squeal phenomenon particularly
in low temperatures. A rubber coating layer a, is formed on one
side of a first constraint plate a.sub.2 of a metallic plate and a
second constraint plate a.sub.4is stuck to the other side of the
first constraint plate a.sub.2 with a adhesive layer a.sub.3 placed
in-between. The ratio of the thickness of the first constraint
plate a.sub.2 to a sum total of the thickness of the back plate b,
forming a disc brake B and the second constraint plate a.sub.4 is
taken as within 0.1 to 0.2, and the second constraint plate a.sub.4
is used so as to be brought into contact with the back plate
b.sub.1.
Inventors: |
Yano, Kunihiko;
(Kawagoe-shi, JP) ; Niwa, Takahiro; (Tokyo,
JP) ; Yoshihara, Masaki; (Kashiba-shi, JP) ;
Arai, Tadashi; (Ikaruga-cho, JP) |
Correspondence
Address: |
FLYNN, THIEL, BOUTELL & TANIS, P.C.
2026 Rambling Road
Kalamazoo
MI
49008-1699
US
|
Family ID: |
18952718 |
Appl. No.: |
10/103585 |
Filed: |
March 21, 2002 |
Current U.S.
Class: |
188/73.37 ;
188/264G |
Current CPC
Class: |
F16F 9/306 20130101;
B32B 15/06 20130101; F16F 2222/02 20130101; B32B 15/18 20130101;
F16D 65/0006 20130101; F16D 65/0979 20130101; B32B 15/043
20130101 |
Class at
Publication: |
188/73.37 ;
188/264.00G |
International
Class: |
F16D 065/38 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2001 |
JP |
2001-099136 |
Claims
What is claimed is:
1. A vibration damping shim structure having a structure, wherein a
rubber coating layer is formed on one side of a first constraint
plate of a metallic plate and the like and a second constraint
plate is stuck to the other side of the first constraint plate with
an adhesive layer placed in-between, and wherein a ratio of the
thickness of the first constraint plate to a sum total thickness of
a back plate of a disc brake pad and the second constraint plate is
taken as within a range of 0.1 to 0.2 and the second constraint
plate is used so as to be brought into contact with the back
plate.
2. The vibration damping shim structure according to claim 1,
wherein a plurality of bubbles is contained in the adhesive
layer.
3. The vibration damping shim structure according to claim 1 or 2,
wherein the adhesive is an acryl pressure sensitive adhesive.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a vibration damping shim
structure for use of a disc brake of an automobile and, more in
particular, to the vibration damping shim structure reducing a high
frequency noise (referred to as a squeal phenomenon), which is
generated at braking.
[0003] 2. Description of the Related Art
[0004] A conventional vibration damping shim structure for disc
brake squealing prevention will be described.
[0005] FIGS. 2 to 3 shows a shim structure disclosed in Japanese
Utility Model Application Laid-Open No.62-45436.
[0006] A shim 60 which is disclosed in this official gazette has a
stainless steel plate 62 and a metallic thin plate 66 coated with a
heat-resistant and oil proof rubber 64 laminated toward the
pressing direction (the direction of an arrow P.sub.2 of FIG. 2) of
a caliper claw 68. The stainless steel plate 62 is arranged on
theside of caliper claw 68 and, as shown in FIG. 3, a plurality of
claws 70 is formed on its periphery. This claw 70 is constituted so
that it is fitted to a back metal 72 of a brake pad. On the other
hand, the thin plate 66 coated with the rubber 64 is arranged on
the side of the back metal 72 and grease 74 is coated on an upper
surface of the rubber 64. As shown in FIG. 3, a plurality of
notches and a grease pool 76 constituted by an oblong hole are
formed on the thin plate 66. The coated grease 74 is accumulated in
this grease pool 76. A claw 78 is formed on the periphery of the
thin plate 66 similarly to the stainless steel plate 62 and is
constituted so that it is fitted to the back plate 72.
[0007] That is, as shown in FIG. 2, the shim 60 of the above
constitution forms a six layer structure of the stainless steel
sheet 62, the grease 74, the rubber 64, the thin plate 66, the
rubber 64 and the grease 74, which is directed toward the pressing
direction of the caliper claw 68.
[0008] The shim 60 of the above-described constitution can stop the
vibration which is the cause of the "squealing noise" by a
vibration insulating operation by interposing the rubber 64 or the
grease 74 between the caliper claw 68 and the back metal 72.
Further, the vibration which is not stopped but propagated can be
damped by a damping operation by a damping action attributable to
an internal friction of the rubber 64 and a damping action
attributable to a sliding friction of the grease 74. Further, a
relative displacement is generated between the back metal 72 (that
is, the brake pad) and the shim 60 by the grease 74 coated between
the back metal 72 and the thin plate 66 and the rubber 64 covered
on the thin plate 66. By frictional damping generated by this
relative displacement, the vibration can be dampened. Further, the
relative displacement is generated between the brake pad and the
shim 60, so that the constraint condition of the brake pad by the
caliper claw 68 is changed. For this reason, the generation of the
vibration can be reduced.
[0009] FIG. 4 shows a shim structure disclosed in Japanese Utility
Model Application Laid-Open No.4-3136.
[0010] A silicon gel layer 92 is provided in the center portion of
a shim 90 which is disclosed in the official gazette. An adhesive
layer 96 comprising an adhesive, an adhesive film and the like is
formed on the side of the caliper claw 94 of the silicon gel layer
92. A steel sheet 98 is arranged on the side of the caliper claw 94
of the adhesive layer 96, and the steel sheet 98 is integrally
bonded to the silicon gel layer 92 by the adhesive layer 96.
[0011] On the other hand, similarly an adhesive layer 102 is formed
on the side of a back metal 100 of the brake pad of the silicon gel
layer 92. A steel sheet 104 is arranged on the side of the back
metal 100 of the adhesive layer 102, and the steel sheet 104 is
integrally bonded to the silicon gel layer 92 by the adhesive layer
102. Further, an adhesive layer 106 comprising the adhesive, the
adhesive film and the like is formed on the side of the back metal
100 of the steel sheet 104, and the steel sheet 104 is bonded to
the back metal 100 by the adhesive layer 106.
[0012] That is, as shown in FIG. 4, the shim 90 of the constitution
forms a six layer structure of the steel sheet 98, the adhesive
layer 96, the silicon gel layer 92, the adhesive layer 102, the
steel sheet 104 and the adhesive layer 106, which is directed
toward the pressing direction (the direction of the arrow p.sub.3
of FIG. 4) of the caliper claw 94 as shown in the sectional view,
and the shim 90 is integrally attached to the back metal 100.
[0013] The silicon gel layer 92 having a good vibration insulating
and flexibility is interposed in the center of the shim 910 of the
constitution, whereby the shim prevents propagation of the
vibration which is the cause of a "brake squealing" by both actions
of the vibration insulating action and the damping action of the
silicon gel layer 92.
[0014] However, the shim structure of the conventional constitution
is unable to obtain a sufficient "brake squealing" prevention
effect as yet. That is, since the grease 74 is coated on the
surface of the rubber 64 of the shim 60 in FIGS. 2 to 3, the
relative displacement of the brake pad is expedited. For this
reason, the effect by the friction damping and the vibration
reducing action by a change in the constraint condition of the
brake pad are excellent. However, since the damping action and the
vibration insulating action are inferior to the silicon gel layer
92 of the shim 90 of FIG. 4, the "brake squealing" cannot be
sufficiently prevented.
[0015] The shim 90 of FIG. 4 comprises the silicon gel layer 92,
which is excellent in vibration insulating and, therefore, the
effect by the damping action and the effect by the vibration
insulating action are excellent. However, since the shim 90 and the
back metal 100 of the brake pad are bonded, the relative
displacement of the brake pad is small, and the effect by the
frictional damping and the effect by the change of the constraint
condition are poor. For this reason, the "brake squealing" cannot
be sufficiently prevented.
[0016] In this way, either one of the conventional shims such as
the shim 60 of FIG. 2 and the shim 90 of FIG. 4 is partially
limited in the effect of preventing the "brake squealing", and the
"brake squealing" cannot be sufficiently prevented so that the
countermeasure to meet the situation has been earnestly
desired.
SUMMARY OF THE INVENTION
[0017] In order to solve the problem, a shim structure shown in
FIGS. 5 and 6 (Japanese Patent Application Laid-Open No.8-232998)
has been proposed.
[0018] In the same drawings, a shim 10 is constituted by a rubber
36 as high frictional means having elasticity, a vibration damping
steel plate 38 as damping means and a grease 40 as low frictional
means having viscosity and fluidity.
[0019] To describe more in detail, the vibration damping steel
plate 38 is arranged in the center of the shim 10. The vibration
damping steel plate 38 comprises a steel plate 44 consist of
stainless and the like arranged at the side of the caliper claw 20
and a steel plate 46 consist of the same material as the steel
plate 44 arranged at the side of the back metal 22. The steel plate
44 and the steel plate 46 are arranged mutually in parallel, and a
viscous member consists of acryl and the like is provided between
the steel plate 44 and the steel plate 46. The steel plate 44, the
viscous member 42 and the steel plate 46 are adhered and integrally
formed. The surface at the side of the caliper claw 20 of the steel
plate 44 is coated with a rubber 36. On the other hand, on the
surface at the side of the back metal 22 of the steel plate 46, a
plurality of grease pools 48 opened toward the pressing direction
(the direction of the arrow P.sub.1 of FIG. 2) of the caliper claw
20 is formed. Further, on the surface of the side of the back metal
22 of the steel plate 46, grease 40 is coated and a part of this
grease 40 is accumulated in the grease pools 48.
[0020] That is, the shim 10 of the constitution forms a five layer
structure of the rubber 36, the steel plate 44, the viscous member
42, the steel plate 46 and the grease 40, which is directed toward
the pressing direction (the direction of the arrow P, of FIG. 1) of
the caliper claw 20 as shown in the sectional view.
[0021] The shim structure can reduce the vibration by the change of
the frictional damping and the constraint condition of the
vibration damping member.
[0022] However, there is a problem, which cannot be solved even in
the shim of this structure. The problem is that, under the
condition of low temperatures in the morning when the automobile
begins to move, the squeal phenomenon generated at the braking
cannot be reduced.
[0023] Nowadays when weight reduction of the automobile is desired,
there is a general tendency to reduce even the weight of the back
plate among the increasing demand for weight reduction of the
parts.
[0024] Accompanied with this tendency, the squeal phenomenon
generated at the low temperature time as described above has a
tendency to remarkably increase.
[0025] The present invention aims to obtain a shim structure which
can sufficiently exert the vibration damping effect in a wide
temperature range.
[0026] The present invention is constituted in such a manner that a
rubber coating layer is formed on one side of a first constraint
plate of a metallic plate and a second constraint plate is stuck to
the other side of the first constraint plate with a adhesive layer
placed in-between. The ratio of thickness of the first constraint
plate to a sum total of the thickness of the back plate of the disc
brake pad and the second constraint plate of the automobile is
taken as within 0.1 to 0.2, and the second constraint plate is used
so as to be brought into contact with the back plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a typical sectional view of a vibration damping
shim structure showing one embodiment of the present invention;
[0028] FIG. 2 is a sectional view showing one Embodiment of a
conventional vibration damping shim structure;
[0029] FIG. 3 is a perspective view of members constituting the
vibration damping shim structure;
[0030] FIG. 4 is a sectional view showing another Embodiment of the
conventional vibration damping shim structure;
[0031] FIG. 5 is a sectional view showing another Embodiment of the
conventional vibration damping shim structure; and
[0032] FIG. 6 is a perspective view of the vibration damping shim
structure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] The form of the present embodiment is constituted in such a
manner that, as shown in FIG. 1, a rubber coating layer a.sub.1 is
formed on one side of a first constraint plate a.sub.2 of a
metallic plate and a second constraint plate a.sub.4 is stuck to
the other side of the first constraint plate a.sub.2 with a
adhesive layer a.sub.3 placed in-between. The ratio of the
thickness of the first constraint plate a.sub.2 to a sum total of
the thickness of the back plate b.sub.1 of the disc brake pad and
the second constraint plate a.sub.4 of the automobile is taken as
within 0.1 to 0.2, and the second constraint plate a.sub.4 is used
so as to be brought into contact with the back plate b.sub.1.
[0034] According to the constitution, the vibration is reduced by a
multiplier action with the damping action by the friction between
the second constraint plate a.sub.4 and back plate b.sub.1, the
vibration insulating action by the adhesive layer a.sub.3 between
the second constraint plate a.sub.4 and the first constraint plate
a.sub.2, the damping action by the internal friction and, further,
the damping action by elasticity of the rubber.
[0035] Further, according to the constitution, all between the back
plate b.sub.1 and the second constraint plate a.sub.4 operate as
one body, and the second constraint plate a.sub.4 and the back
plate b.sub.1 are related so as to be integrated for the first
constraint plate a.sub.2, and in the form where the first
constraint plate a.sub.2 and (the second constraint plate a.sub.4 +
the back plate b.sub.1) exist via the adhesive layer a.sub.3, the
ratio of the thickness of the first constraint plate a.sub.2 to the
second constraint plate a.sub.1 + the back plate b.sub.1 is taken
as within a range of 0.1 to 0.2, so that improvement of the
squealing prevention effect is remark ably recognized.
[0036] This improvement of the squealing prevention effect can be
considered as follows:
[0037] (1) By making a board thickness of the first constraint
plate thicker, the thickness is brought near the thickness of (the
second constraint plate + the back plate), thereby improving a
vibration damping performance.
[0038] (2) With respect to the squealing due to resonance of a
rotor and a pad, by making a board thickness of the first
constraint plate thicker, an natural frequency of the pad attached
to the shim is lowered so that the resonance of the rotor and the
pad is prevented and the generation of the squealing is
prevented.
[0039] (3) By making a board thickness of the first constraint
plate thicker, mechanical strength of the shim is improved so that
a brake system can be strong enough to endure rigorous braking.
[0040] (4) By making a board thickness of the first constraint
plate thicker, it is possible to change inherent vibration
frequency of the pad so that resonance frequency of the squealing
at the pad can be shifted.
[0041] (5) When an adhesive having a glass transition point at most
-25.degree. C. is used, vibration damping properties at low
temperatures (0 to 10.degree. C.) are improved.
[0042] (6) The shim structure whose vibration damping performance
was improved at such low temperatures is very effective in
preventing the squealing generated when the temperatures are
low.
[0043] (7) The temperatures being limited within such a range, it
is possible to make workability, productivity and operationality
excellent.
[0044] FIG. 1 is a sectional view typically showing a structure of
a brake pad vibration damping shim structure according to the
present invention, which shows a state of a vibration damping shim
structure A being arranged on the surface of a back plate b.sub.1
forming a brake pad B.
[0045] Reference numeral a.sub.1 forms a rubber coating layer,
a.sub.2 a first constraint plate, a.sub.3 an adhesive layer,
a.sub.4 a second constraint layer, and b.sub.2 a frictional member
forming a brake pad B.
[0046] As for the constraint plates a.sub.2, a.sub.4 which
constitute the shim structure A, for Embodiment, a metallic plate
such as an iron plate (steel cold rolled plate), an aluminum plate,
a stainless plate, a copper plate and the like can be enumerated.
The constraint plates include those treated with coating on the
surface of the metallic plates for the purpose of rust prevention,
corrosion prevention and the like.
[0047] On the other hand, as for the rubber material to be used for
the rubber coating layer a.sub.1, NBR (acrylonitrile-butadiene
rubber), SBR (styrene-butadiene rubber), IR (isoprene rubber), BR
(butadiene rubber), CR (chloroprene rubber), IIR (butyl rubber),
EPM (ethylene-propylene rubber), EDDM (ethylene-propylene rubber),
FKM (fluororubber) and the like can be enumerated. Particularly, in
order to obtain a good intimacy, the hardness of the rubber coating
layer is at most 90, or preferably at most 70 at durometer hardness
A.
[0048] As for the adhesive of the adhesive layer a.sub.3, acryl,
rubber, silicon and the like can be enumerated and, for the
practical purpose, use of acryl (cross linking type)
pressure-sensitive type adhesive is preferable.
[0049] Among acryl adhesives, particularly those having a glass
transition point (Tg) at most -25.degree. C. are effective to
improve vibration damping at low temperatures. In the following
embodiments, the adhesive having the Tg at most--31.degree. C. is
used.
[0050] Bubbles may be included in the adhesive. In order to include
bubbles in the adhesive, there are methods of automatically mixing
bubbles by agitating the adhesive, mixing a blowing agent in the
adhesive so as to allow it to bubble by generating pyrolytic gas,
thermally expanding a microcapsule, coating the adhesive on a
porous surface and allowing the adhesive on the porous surface to
bubble by heating and the like. Porosity as the bubble contained
adhesive is preferred to be within a range of 5 to 80% and a
poro-size 10 to 300 .mu.m.
[0051] Next, practical embodiments of the present invention will be
described.
Embodiment (1)
[0052] The vibration damping shim structure shown in FIG. 1 was
fabricated by the following materials and thickness:
[0053] A steel cold rolled plate a.sub.2 having a thickness of 0.8
mm, a rubber coating layer a.sub.1 having a thickness of 0.1 mm, a
acryl pressure sensitive adhesive layer a.sub.3 having a thickness
of 0.11 mm, a stainless plate a.sub.4 Shaving a thickness of 0.4 mm
and aback plate behaving a thickness of 6 mm.
Embodiment (2)
[0054] The thickness of the steel cold rolled plate a.sub.2 is made
0.6 mm by using the material of the embodiment (1) and, with other
materials having the same structure as the embodiment (1), the
vibration damping shim structure was fabricated.
Embodiment (3)
[0055] The thickness of the steel cold rolled plate a.sub.2 is made
0.9 mm by using the material of the embodiment (1) and, with other
materials having the same structure as the embodiment (1), the
vibration damping shim structure was fabricated.
Comparative Embodiment (1)
[0056] The thickness of the steel cold rolled plate a.sub.2 is made
0.5 mm by using the material of the embodiment (1) and, with other
materials having the same structure as the embodiment (1), the
vibration damping shim structure was fabricated.
Comparative Embodiment (2)
[0057] The thickness of the steel cold rolled plate 10 is made 0.4
mm by using the material of the embodiment (1) and, with other
materials having the same structure as the embodiment (1), the
vibration damping shim structure was fabricated.
[0058] With respect to the embodiments (1) to (3) and the
comparative Embodiments (1), (2), the brake squealing prevention
performance of the vibration damping shim structure was measured by
using a brake squealing dynamo tester in a temperature of 5.degree.
C. The result is shown in the following Table 1.
1TABLE 1 SQUEALING SOUND PRESSURE SQUEALING ITEM LEVEL (MAXIMUM)
RATE (%) Embodiment (1) 0 dB 0 Embodiment (2) 86 dB 4 Embodiment
(3) 0 dB 0 Comparative Embodiment (1) 94 dB 15 Comparative
Embodiment (2) 97 dB 20 WHAT IS MEANT BY SQUEALING RATE IS NUMBER
OF BRAKE SQUEALING TO NUMBER OF BRAKING OF DISC BRAKE.
[0059] As described above, according to the present invention, a
shim structure can be obtained, whose constitution is such that a
rubber coating layer is formed on one side of a first constraint
plate of a metallic plate and the like and a second constraint
plate is stuck to the other side of the first constraint plate with
a adhesive layer placed in-between, and wherein the ratio of the
thickness of the fist constraint plate to a sum total thickness of
the back plate of the disc brake pad of the automobile and the
second constraint plate is taken as within a range of 0.1 to 0.2,
and the second constraint plate is used so as to be brought into
contact with the back plate so that the shim structure capable of
preventing the squeal phenomenon at low temperatures can be
obtained.
* * * * *