Aluminum alloy bracket for fixing elastic mount, assembly of elastic mount and bracket, and method of producing the bracket by extrusion

A bracket made of an aluminum alloy for fixing an elastic mount to one of two members to be elastically connected to each other through the elastic mount interposed therebetween. The bracket is formed by extrusion, and has at least one aperture formed therethrough so as to extend in the direction of extrusion. A first succession of recessed and raised portions are formed on at least a part of a fixing surface that is fixable to the elastic mount, and a second succession of recessed and raised portions are formed on at least a part of an exposed surface thereof which is exposed to the atmosphere upon fixing of the bracket to the elastic mount. The recessed and raised portions extend in the direction of extrusion, and are formed alternately in a direction perpendicular to the direction of extension.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a bracket for fixing a rubber mount or 
elastic mount to one of two members which are elastically connected to 
each other through the elastic mount, an assembly of the elastic mount and 
the bracket, and a method of producing the bracket. 
2. Discussion of the Related Art 
In a vibration system such as a system adapted to elastically support a 
vibrating member like a power unit including an internal combustion engine 
and a muffler or exhaust pipe, there is known an elastic mount including a 
rubber member, which is interposed between two members which are 
elastically connected to each other through the elastic mount so as to 
damp a vibrational load applied therebetween. A metallic bracket is 
usually used for fixing such an elastic mount to one of those two members, 
taking account of the fixing efficiency and the construction of the member 
to which the elastic mount is fixed. In particular, brackets made of an 
aluminum alloy have been recently employed in place of conventional iron 
brackets, in an effort to reduce the weight and increasing the natural 
frequency (resonance frequency) of the bracket. 
Generally, aluminum alloys have generally higher thermal conductivity than 
irons, and heat is more likely to be transferred through the aluminum 
alloy bracket from the member to which the elastic mount is fixed, to the 
elastic mount. Therefore, where the elastic mount is an engine mount fixed 
to an engine or a muffler mount fixed to a muffler, the elastic mount 
tends to be heated due to transfer of heat from the engine or muffler to 
the elastic mount, whereby the elastic mount tends to suffer from thermal 
deterioration and reduced durability. 
While the elastic mount may be made of a highly heat-resistant rubber 
material, this solution to the above problem results in reduced freedom of 
choice of the rubber material, making it difficult to provide the elastic 
mount with desired dynamic vibration damping characteristics (e.g., a 
sufficiently high dynamic spring constant). Therefore, the above solution 
is not necessarily satisfactory. 
SUMMARY OF THE INVENTION 
It is therefore a first object of the present invention to provide an 
aluminum alloy bracket for fixing an elastic mount to one of two members 
to be elastically connected to each other through the elastic mount, which 
bracket is simple in construction, easy to manufacture and effective to 
minimize heat transfer from the member in question to the elastic mount to 
thereby prevent or minimize thermal deterioration of the elastic mount. 
It is a second object of the invention to provide an assembly of an elastic 
mount and such an aluminum alloy bracket. 
It is a third object of the invention to provide a method of producing the 
aluminum alloy bracket. 
The first object indicated above may be achieved according to a first 
aspect of this invention, which provides a bracket made of an aluminum 
alloy for fixing an elastic mount to one of two members which are to be 
elastically connected to each other through the elastic mount interposed 
therebetween, wherein the bracket is formed by extrusion of the aluminum 
alloy, and has at least one aperture formed therethrough so as to extend 
in a direction of extrusion of the aluminum alloy, and also has a first 
succession of recessed and raised portions formed on at least a part of a 
fixing surface thereof at which the bracket is fixed to the elastic mount, 
and a second succession of recessed and raised portions formed on at least 
a part of an exposed surface thereof which is exposed to an atmosphere 
when the bracket is fixed to the elastic mount and the above-indicated one 
of the two members. The recessed and raised portions of each of the first 
and second successions extend in the direction of extrusion, and are 
formed alternately in a direction perpendicular to the direction of 
extension. 
The exposed surface may include surfaces defining the aperture or 
apertures. Namely, the recessed and raised portions may be formed on the 
desired parts of the surfaces of the aperture or apertures. 
In the bracket constructed according to the first aspect of this invention, 
the aperture or apertures and the second succession of recessed and raised 
portions formed on the exposed surface contribute to an increase in the 
area of the surface which is exposed to the atmosphere and from which heat 
is dissipated from the bracket, whereby the present bracket exhibits a 
sufficiently high degree of heat dissipation or cooling efficiency. 
Accordingly, the amount of heat that is transferred through the bracket to 
the elastic mount is effectively reduced, with a result of preventing or 
minimizing an increase in the temperature of the elastic mount due to the 
heat transfer thereto through the bracket, thereby preventing or 
minimizing deterioration of durability of the elastic mount due to the 
heat transfer. Further, the present bracket is effective to reduce the 
required heat resistance of the rubber material of the elastic mount, 
thereby permitting increased freedom of choice of the rubber material, 
resulting in increased freedom of design of the elastic mount regarding 
its damping characteristics. Thus, the bracket according to the present 
invention permits the elastic mount to be easily designed so as to exhibit 
the desired damping characteristics with high stability. 
It is noted that the apertures and the recessed and raised portions may be 
easily and economically formed in the process of extrusion of the bracket, 
without any machining operations, whereby the bracket is available at a 
relatively low cost. 
Further, the first succession of recessed and raised portions formed on the 
fixing surface of the bracket provides a relatively large area for bonding 
to the elastic mount, where an assembly of the elastic mount and the 
bracket is fabricated by vulcanization of the rubber material to form the 
elastic mount. In this case, the bracket can be firmly bonded at its 
fixing surface having the recessed and raised portions to the elastic 
mount, with a sufficiently large bonding force therebetween, without any 
metal parts and bolts or other fastening means which would be otherwise 
required for mechanically fixing the bracket and the elastic mount. 
Accordingly, the elastic mount can be simplified without a metal fitting. 
Even where the bracket is directly bonded to the elastic mount, the amount 
of heat transferred from the bracket to the elastic mount is reduced owing 
to the increased surface area of heat dissipation provided the surfaces of 
the aperture or apertures and the recessed and raised portions formed on 
the exposed surface, whereby the thermal deterioration of the elastic 
mount is minimized. 
In one preferred form of the bracket according to the present invention, 
the first succession of recessed and raised portions has a dimension of 
0.3-1.0 mm, which is a distance between the bottom of the recessed 
portions and the top of the raised portions, as measured in a direction 
perpendicular to the fixing surface and the exposed surface. Further, the 
recessed and raised portions of the first succession are alternately 
formed at a pitch of 0.5-2.0 mm in the direction perpendicular to the 
direction of extension. 
The first succession of recessed and raised portions dimensioned as 
described above assures a sufficiently large force of bonding between the 
bonding (fixing) surface of the bracket and the corresponding surface of 
the elastic mount, and makes it possible to reduce local stress 
concentration at the bonding interface between the bracket and the elastic 
mount. Accordingly, the recessed and raised portions dimensioned according 
to the above-indicated preferred form of the invention are effective to 
prevent cracking of the elastic mount due to the local stress 
concentration, which would deteriorate the durability of the elastic 
mount. If the dimension between the bottom and top of the adjacent 
recessed and raised portions is smaller than 0.3 mm, or the pitch of the 
alternate recessed and raised portions is larger than 2.0 mm, the effect 
of the recessed and raised portions to increase the area of the fixing 
surface of the bracket is not sufficient. If the above-indicated dimension 
is larger than 1.0 mm or the pitch is smaller than 0.5 mm, the adjacent 
recessed and raised portions tend to form a relatively sharp edge 
therebetween, leading to a risk of local stress concentration at the 
bonding interface between the fixing surface of the bracket and the 
corresponding surface of the elastic mount, and consequent deterioration 
of the durability of the elastic mount. Further, the extruding operation 
using an extruder die to form the bracket tends to be difficult in the 
latter case. 
In another preferred form of the bracket of the present invention, the 
recessed and raised portions of the first succession cooperate with each 
other to define a continuously corrugated surface which provides the 
above-indicated part of the fixing surface. The term "continuously 
corrugated surface" is interpreted to mean a corrugated surface which does 
not have discontinuity or sharp edges or bends between the adjacent 
recessed and raised portions. For instance, each of the recessed and 
raised portions of each of the first and second successions may be defined 
by a surface which is substantially arcuate in cross section taken in a 
plane which is perpendicular to the direction of extrusion and the fixing 
and exposed surfaces. In this case, the adjacent recessed and raised 
portions have common tangent lines. 
The above preferred form of the bracket is advantageous particularly when 
it is bonded to the elastic mount. Namely, the arcuately shaped recessed 
and raised portions are effective to reduce the local stress concentration 
at the bonding interface between the bracket and the elastic mount, 
resulting in an increase in the durability of the elastic mount. 
The second succession of recessed and raised portions formed on the exposed 
surface of the bracket contributes to an increase in the surface area of 
heat dissipation of the bracket. For effectively increasing the surface 
area of heat dissipation and facilitating the extrusion, the second 
succession of recessed and raised portions is also preferably dimensioned 
as described above with respect to the first succession of recessed and 
raised portions. That is, the dimension between the bottom and top of the 
adjacent recessed and raised portions of the second succession formed on 
the exposed surface is preferably selected within the range of 0.3-1.0 mm, 
while the pitch is selected within the range of 0.5-2.0 mm. Further, the 
recessed and raised portions of the second succession are also preferably 
defined by substantially arcuate surfaces, for avoiding sharp edges on the 
exposed surface, which may cause undesirable reduction in the cooling 
effect of the exposed surface due to air staying at such sharp edges. 
The second object indicated above may be achieved according to a second 
aspect of this invention, which provides an assembly for elastically 
connecting two members to each other, including an elastic mount and a 
bracket for fixing an elastic mount to one of the two members, wherein the 
bracket is formed by extrusion, and has at least one aperture formed 
therethrough so as to extend in a direction of extrusion of the bracket, 
and also has a first succession of recessed and raised portions formed on 
at least a part of a bonding surface thereof at which the bracket is 
bonded to the elastic mount, and a second succession of recessed and 
raised portions formed on at least a part of an exposed surface thereof 
which is exposed to an atmosphere when the bracket is bonded to the 
elastic mount and the above-indicated one of the two members. The recessed 
and raised portions of each of the first and second successions extend in 
the direction of extrusion, and are formed alternately in a direction 
perpendicular to the direction of extension, and wherein the elastic mount 
is bonded directly to the bonding surface of the bracket. 
In the assembly of the elastic mount and the bracket according to the 
second aspect of this invention, the elastic mount is bonded to the 
bracket which has the aperture or apertures and the first and second 
successions of recessed and raised portions as described above with 
respect to the first aspect of the invention. Accordingly, the amount of 
heat transferred through the bracket to the elastic mount is significantly 
reduced to minimize an increase in the temperature of the elastic mount, 
and the bonding force between the bracket and the elastic mount is 
effectively increased. The present assembly which has increased durability 
and is capable of exhibiting improved damping characteristics is simple in 
construction and is available at a relatively low cost. 
For further increase of the bonding strength between the bracket and the 
elastic mount and further increase of the durability elastic mount, it is 
preferred that the dimension between the bottom and top of the adjacent 
recessed and raised portions formed on the bonding surface of the bracket 
be selected within a range of 0.3-2.0 mm, while each of the recessed and 
raised portions of the first succession be defined by a substantially 
arcuate surface, as described above with respect to the first aspect of 
the invention. 
The third object indicated above may be achieved according to a third 
aspect of this invention, which provides a method of producing a bracket 
made of an aluminum alloy for fixing an elastic mount to one of two 
members which are to be elastically connected to each other through the 
elastic mount interposed therebetween, the bracket having a fixing surface 
at which the bracket is fixed to the elastic mount, and an exposed surface 
which is exposed to an atmosphere when the bracket is fixed to the elastic 
mount and the above-indicated one of the two members, the method 
comprising the steps of: forming an extruded structure by extruding an 
aluminum alloy, such that the extruded structure has at least one aperture 
formed therethrough so as to extend in a direction of extrusion of the 
aluminum alloy, and a first succession of recessed and raised portions 
formed on at least a part of a first surface thereof corresponding to the 
fixing surface of the bracket, and a second succession of recessed and 
raised portions formed on at least a part of a second surface thereof 
corresponding to the exposed surface of the bracket, the recessed and 
raised portions of each of the first and second successions extending in 
the direction of extrusion, and being formed alternately in a direction 
perpendicular to the direction of extension; and cutting the extruded 
structure in a plane perpendicular to the direction of extrusion, into a 
plurality of pieces each having has a predetermined dimension in the 
direction of extrusion, the each piece providing the bracket having at 
least one aperture corresponding to the at least one aperture of the 
extruded structure, and a first succession of recessed and raised portions 
and a second succession of recessed and raised portions which correspond 
to the first and second successions of recessed and raised portions formed 
on the first and second surfaces of the extruded structure, respectively, 
the first succession of recessed and raised portions of the bracket being 
formed on at least a part of the fixing surface, while the second 
succession of recessed and raised portions of the bracket being formed on 
at least a part of the exposed surface. 
According to the method of the third aspect of the present invention, the 
bracket according to the first aspect aspect of the invention or the 
bracket of the assembly according to the second aspect of the invention 
may be produced with high efficiency, by extrusion of the aluminum alloy 
to form the extruded structure and by cutting this extruded structure. 
Namely, the extruded structure is formed with at least one aperture 
corresponding to at least one aperture of the bracket, and recessed and 
raised portions corresponding to the first and second successions of 
recessed and raised portions formed on the fixing and exposed surfaces of 
the bracket. These apertures and recessed and raised portions for reducing 
the amount of heat transferred through the bracket to the elastic mount 
and for increasing the bonding strength between the bracket and the 
elastic mount are formed in the process of extrusion of the aluminum 
alloy, without any machining. In addition, a plurality or multiplicity of 
brackets can be produced by cutting the extruded structure into respective 
pieces, so that the production efficiency of the bracket is considerably 
high.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIGS. 1-3, there is shown an assembly 10 according to 
one embodiment of this invention. The assembly 10 consists of an elastic 
mount in the form of an engine mount 12 including an elastic body made of 
a rubber material, and a bracket 14 made of an aluminum alloy. The 
assembly 10 is interposed between a body 16 of an automotive vehicle and a 
power unit 18 including an engine, so that these two members 16, 18 are 
elastically connected to each other through the elastic body 12. Namely, 
the power unit 18 is mounted on the vehicle body 16 through the engine 
mount 12, in a vibration damping manner. In FIG. 1, the vehicle body 16 
and power unit 18 are indicated by two-dot chain lines. 
Described in detail, the engine mount 12 includes an elastic body 20 which 
is a rectangular block of a suitable rubber material. The elastic body 20 
has two opposite mounting surfaces 22, 28. In the process of vulcanization 
of the rubber material to form the elastic body 20, a rectangular mounting 
plate 24 is bonded to the lower mounting surface 22. The mounting plate 24 
is provided with a fixing bolt 26 which has a head portion and an 
externally threaded portion. The head portion is embedded in the elastic 
body 20 and is secured to the inner surface of the mounting plate 24. The 
externally threaded portion of the fixing bolt 26 extends through a 
central portion of the mounting plate 24 in an outward direction away from 
the mounting surface 22. The engine mount 12 is fixed at its mounting 
plate 24 to the vehicle body 16 by the fixing screw 26. 
To the other or upper mounting surface 28 of the elastic body 20, there is 
bonded the bracket 14 in the above-indicated vulcanization process. This 
bracket 14 is bolted to the power unit 18 of the vehicle, so that the 
engine mount 12 is fixed to the power unit 18 through the bracket 14. 
The bracket 14 is a structure having a generally rectangular shape as seen 
in top and bottom plans views in FIGS. 2 and 3, and is bent at an 
intermediate portion A, which is intermediate as viewed in a longitudinal 
direction (in the horizontal direction as seen in FIGS. 2 and 3). The bend 
extends over the entire width of the intermediate portion A, the width 
direction (vertical direction as viewed in FIGS. 2 and 3) being 
perpendicular to the longitudinal direction. The bracket 14 includes a 
first portion 30 on one side of the intermediate bent portion A. The first 
portion 30 has a bolt hole 32 formed through the thickness of a part near 
its free end remote from the intermediate bent portion A. The bracket 14 
is fixed at its first fixing portion 30 to the power unit 18 indicated by 
two-dot chain line in FIG. 1, with a bolt 34 inserted through the bolt 
hole 32. 
The thickness of the first portion 30 decreases in the longitudinal 
direction from the above-indicated free end to the fixed end adjacent the 
intermediate portion A, and includes a second portion on the other side of 
the intermediate bent portion A remote from the first portion 30. The 
second fixing portion 36 has a bonding portion 38 which is a lower surface 
as seen in FIG. 1. The bracket 14 is bonded at this bonding surface 38 to 
the upper mounting surface 28 of the elastic body 20 of the engine mount 
12. Thus, the engine mount 12 is fixed to the power unit 18 through the 
bracket 14. 
As described above, the bracket 14 is fixed at its first portion 30 to the 
power unit 18, and at its second portion 12 to the engine mount 36, so 
that the engine mount 12 is fixed to the power unit 18 through the bracket 
14. 
The bracket 14 has thirteen apertures 40 formed therethrough in the width 
direction (perpendicular to the plane of FIG. 1). Each of these apertures 
40 has a predetermined constant cross sectional shape over the entire 
width of the bracket 14. The apertures 40 are substantially evenly 
distributed in the longitudinal direction of the bracket 14, such that the 
adjacent apertures 40 are spaced apart from each other by a suitable 
distance in the longitudinal direction. 
The bonding surface 38 of the second fixing portion 36 has a first 
succession of recessed and raised portions 44, 46, as shown in FIG. 4. 
These recessed and raised portions 44, 46 are formed so as to extend in 
parallel with each other over the entire dimension of the second fixing 
portion 36 in the width direction. The recessed and raised portions 44, 46 
are formed alternately in the longitudinal direction of the bracket 14. As 
shown in FIG. 1, a second succession of recessed and raised portions 44, 
46 is formed on the other surface 48 of the second portion 36 which 
cooperates with the bonding portion 38 to define the thickness of the 
second portion 36, and is also formed the adjacent surface 50 of the 
intermediate portion A and a part 52 of the surface of the first fixing 
portion 30, which part 52 is adjacent to the surface 50 of the 
intermediate portion A. These surfaces 48, 50, 52 are exposed to the 
atmosphere and are collectively referred to as "exposed surface". The 
second succession of recessed and raised portions 44, 46 formed on the 
surfaces 48, 50, 52 is similar in configuration and dimension to the first 
succession of recessed and raised portions 44, 46 formed on the bonding 
surface 38. 
Described more specifically, the alternately formed parallel recessed and 
raised portions 44, 46 extending over the entire width of the bracket 14 
have a depth or height dimension H which is preferably selected within a 
range of 0.3-1.0 mm. As indicated in the enlarged cross sectional view of 
FIG. 4, the dimension H is a distance between the bottom of each recessed 
portion 44 and the top of the adjacent raised portion 46, as measured in a 
direction perpendicular to the bonding surface 38 and the exposed surface 
48, 50, 52. Further, the adjacent recessed and raised portions 44, 46 
preferably have a center-to-center distance P in the longitudinal 
direction in which the recessed and raised portions 44, 46 are alternately 
formed. The center-to-center distance P is a distance between the center 
of each recessed portion 44 and the center of the adjacent raised portion 
46, as measured in the longitudinal direction. In other words, the 
recessed and raised portions 44, 46 are alternately formed at a pitch 
equal to the center-to-center distance P in the longitudinal direction, as 
indicated in FIG. 4. This distance P is preferably selected within a range 
of 0.5-2.0 mm. 
Each of the recessed and raised portions 44, 46 is defined by a surface 
which is substantially arcuate in cross section taken in a plane which is 
perpendicular to the direction of extrusion and the bonding surface 38 and 
the exposed surface 48, 50, 52. These arcuate surfaces of the adjacent 
recessed and raised portions 44, 46 are continuously connected to each 
other without discontinuity or a sharp edge or bend, whereby the bonding 
surface 38 and the surfaces 48, 50, 52 indicated above are continuously 
curved or corrugated in the form of a wave. 
The bracket 14 having the apertures 40 and the succession of recessed and 
raised portions 44, 46 may be readily produced in an extrusion process, as 
described above. 
That is, a cast ingot of an aluminum alloy having a suitable composition is 
subjected to an extruding operation using a suitable die, to produce an 
extruded structure having the same cross sectional shape as the bracket 
14. Namely, the extruded structure has apertures and recessed and raised 
portions corresponding to the apertures 40 and the first and second 
successions of recessed and raised portions 44, 46 of the bracket 14. 
Those apertures and recessed and raised portions of the extruded structure 
are formed so as to extend in the direction of extrusion of the aluminum 
alloy ingot. The aluminum alloy used is preferably an Al--Mg--Si alloy 
according to JIS A6061 (AA6061) and JIS A6N01, or an alloy similar to this 
alloy, for improving the strength and corrosion resistance of the extruded 
bracket 14. Commonly known extrusion techniques may be used for 
fabricating the bracket 40. However, hot-extrusion techniques are 
preferred. 
The extruded structure is then cut in parallel planes perpendicular to the 
direction of extrusion, into pieces each having a width dimension equal to 
the width of the bracket 14. The extruded structure or each piece obtained 
by cutting the extruded structure is subjected to a drilling operation to 
form the bolt hole 32. Thus, the bracket 14 corresponding to each piece 
obtained by cutting the extruded structure is produced. Before this 
cutting step, the extruded structure is subjected to suitable operation or 
operations for removing strains in the extruded structure. Further, the 
extruded structure is subjected to a suitable heat treatment step such as 
hardening, before or after the cutting step. 
The assembly 10 consisting of the engine mount 12 and the bracket 14 thus 
fabricated is obtained by: preparing the mounting plate 24 with the fixing 
bolt 26 secured thereto; positioning the bracket 14 and this mounting 
plate 24 in a suitable mold, such that the second portion 36 of the 
bracket 14 is opposed to the mounting bracket 24; and vulcanizing a 
suitable rubber material injected between the fixing portion 36 and the 
mounting plate 24, so as to form the elastic body 20 which is bonded at 
its mounting surface 22 to the mounting plate 24 and at the mounting 
surface 28 to the bracket 14. With the succession of recessed and raised 
portions 44, 46 being formed on the bonding portion 38 of the bracket 14, 
the mounting surface 28 of the elastic body 20 is curved or corrugated 
following the profile of the recessed and raised portions 44, 46 of the 
bonding surface 38, so that the mounting surface 28 is securely bonded to 
the bonding surface 38. 
In the assembly 10 constructed as described above, the bracket 14 has a 
sufficiently large surface area exposed to the atmosphere, in the presence 
of the apertures 40, and the recessed and raised portions 44, 46 formed on 
the surface 48 on one side of the the bracket 14 opposite to the bonding 
surface 38, and the surfaces 50, 52 adjacent to the surface 48. 
Consequently, the heat is effectively dissipated from the bracket 14 so as 
to cool the bracket 14, so that the heat transfer from the power unit 18 
to the engine mount 12 through the bracket 14 is minimized so as to 
prevent or minimize the deterioration of the elastic body 20 of the engine 
mount 12 due to the heat transferred through the bracket 14. Accordingly, 
the durability of the engine mount 12 is improved according to the present 
embodiment. 
Further, the succession of recessed and raised portions 44, 46 on the 
bonding surface 38 provide the elastic body 20 with a sufficiently large 
area of bonding to the second fixing portion 36 of the bracket 14. 
Accordingly, the force and durability of bonding between the elastic body 
and the bracket 14 are increased. In addition, the direct bonding of the 
elastic body 20 to the bracket 14 eliminates metal parts and fastening 
means such as bolts which would be otherwise required for fixing the 
engine mount 12 to the bracket 14. This arrangement is effective to reduce 
the number of the required parts and the weight of the assembly 10, 
simplify the construction of the assembly 10, and facilitate the 
manufacture of the assembly 10. 
It is also noted that since the corrugated bonding portion 38 consisting of 
the alternately formed recessed and raised portions 44, 46 is a 
continuously curved surface without a sharp edge or bend, damages of the 
elastic body 20 such as cracking due to local stress concentration are 
effectively prevented or reduced, permitting a further improvement in the 
bonding force and durability of the elastic body 20 with respect to the 
bracket 14. As indicated above, the recessed and raised portions 44, 46 
each having an arcuate shape has a radius of curvature r, which is 
preferably selected to satisfy 0.3 mm.ltoreq.r.ltoreq.1.0 mm. Further, the 
radius of curvature r of each recessed portion 44 is preferably equal to 
that of each raised portion 46. These arrangements assure improved 
continuity of corrugation of the bonding portion 38 over the entire area, 
and prevent local stress concentration in the elastic body 20 which would 
take place due to the curvature having a small radius, whereby the elastic 
body 20 can be bonded to the bracket 14 with further increased bonding 
force and durability. 
Where the recessed and raised portions 44, 46 formed on the surfaces 48, 
50, 52 are shaped and dimensioned like the recessed and raised portions 
44, 46 formed on the bonding surface 38, those recessed and raised 
portions 44, 46 provided for cooling the bracket 14 by heat dissipation do 
not suffer from undesirable air staying adjacent to the surfaces 48, 50, 
52, in the absence of sharp edges or bends between the adjacent recessed 
and raised portions 44, 46, and have a sufficiently large strength owing 
to the sufficiently large radius of curvature. In addition, the present 
arrangement makes it possible to improve the fabricating efficiency of the 
bracket 14 by extrusion. 
According to the method of producing the bracket 14 described above, the 
apertures 40 and the recessed and raised portions 44, 46 can be formed 
simultaneously with the formation of the bracket 14 by extrusion. 
Accordingly, the present method permits the bracket 14 to be produced with 
improved efficiency and reduced cost, while assuring improved cooling or 
heat dissipating efficiency and increased bonding strength with respect to 
the elastic body 20, as discussed above. 
In addition, the apertures 40 and the recessed and raised portions 44, 46 
have desired shapes and dimensions with high stability, since they are 
formed in the process of extrusion to form the bracket 14, rather than by 
machining subsequent to the formation of the bracket 14. Consequently, the 
method according to the present embodiment permits the production of the 
bracket 14 with a reduced ratio of reject, while assuring the reduction of 
heat transfer and the increased force of bonding to the elastic body 20, 
with a high degree of stability. 
Further, the present method using an extrusion technique makes it possible 
to fabricate an extruded one-piece structure which is a precursor for 
producing a large number of brackets 14 at one time. Accordingly, the cost 
of manufacture of each bracket 14 is reduced. 
While the presently preferred embodiment of this invention has been 
described above for illustrative purpose only, it is to be understood that 
the invention is not limited to the details of the illustrated embodiment, 
but may be otherwise embodied. 
For instance, the configurations and construction of the first portion 30 
fixed to the power unit 18 and the second portion 36 fixed to the engine 
mount 12 may be modified as needed, depending upon the configurations of 
the power unit 18 and engine mount 12, and the required strength of the 
bracket 14, for instance. 
Similarly, the configuration and construction of the engine mount 12 may be 
modified as needed, depending upon the required damping characteristics. 
Various known types of engine mounts may be used with the bracket 14. 
The recessed and raised portions 44, 46 may be formed on the selected one 
or ones of the surfaces which define the selected ones of the apertures 
40. In this case, the area of the exposed surface of the bracket 14 is 
further increased for improved efficiency of heat dissipation from the 
bracket 14. 
Although the assembly 10 consisting of the engine mount 12 and the bracket 
14 and the method of producing the assembly 10 have been described above, 
the principle of the present invention is equally applicable to a bracket 
for fixing any type of elastic mount other than the engine mount, an 
assembly of such elastic mount and bracket, and a method of producing the 
bracket. For instance, the present invention is applicable to a bracket 
for a muffler mount for mounting a muffler on the body of an automotive 
vehicle, and a bracket for various elastic mounts not used on the 
automotive vehicle. The principle of the present invention can be 
advantageously practiced particularly where the bracket is used in an 
environment in which heat is likely to be transferred through the bracket 
to an elastic mount which is fixed to one of two members that are to be 
elastically connected to each other through the elastic mount. 
It is to be understood that the present invention may be embodied with 
various other changes, modifications and improvements, which may occur to 
those skilled in the art, without departing from the scope of the 
invention defined in the following claims: