1
FORM 2
THE PATENT ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “A BUSH ASSEMBLY”
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the invention and the manner in which
it is to be performed.
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TECHNICAL FIELD
Embodiments of the present disclosure relates to a bush assembly for suspension system
of a vehicle, more particularly embodiments relates to a variable rate bush assembly.
BACKGROUND OF DISCLOSURE
Bushes are an integral part of a vehicle suspension. Suspension bushes are the isolators
that provide dampening and allow the suspension parts to move freely, for example,
when traveling over a large bump, while minimizing transmission of noise and small
vibrations through to the chassis of the vehicle. Bushes also play an important role in
deciding the ride quality and the various suspension handling curves and also determine
the impact harshness of the vehicle. The proper stiffness of the bushes thus becomes very
important. The stiffness of the bushes at every hard point of the suspension is different
for the best performance of the suspension. Also at certain suspension hard points the
stiffness of the bush is different in different radial and axial directions. Thus a suspension
of a vehicle can have many bushes each of different stiffness. The number of suspension
bushes with different stiffness in a passenger car can vary from 3 to 10 depending on the
type of suspension. During the development phase of the suspension, different bush
stiffness is tried at each location of the suspension and different bush is to be
manufactured for facilitating different stiffness in different points of suspension. This
incurs very high development cost of the bushes and thus the suspension. Also having
bushes of different stiffness in the suspension calls for higher cost of parts and
complexity in material handling and related cost.
Further, the bushes are also used in various machines to reduce the vibrations produced
by the machine. And different bush is to be manufactured for using in different machines,
which will increase the cost of production.
In light of foregoing discussion, it is necessary to provide a variable rate bush assembly
which can be fitted at different locations of suspension system by varying the stiffness to
overcome the limitations stated above.
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SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided
through the provision of assembly as claimed in the present disclosure.
Additional features and advantages are realized through the techniques of the present
disclosure. Other embodiments and aspects of the disclosure are described in detail herein
and are considered a part of the claimed disclosure.
One embodiment of the present disclosure relates to a bush assembly. The bush assembly
comprises an outer bush of predetermined shape comprising a first bonded metallic
sleeve, a second metallic sleeve disposed concentrically inside the first bonded metallic
sleeve, and a rubber bonded in between the first bonded metallic sleeve and the second
metallic sleeve, wherein said rubber comprises two or more voids of predetermined shape
to facilitate variable stiffness in the outer bush. The bush assembly also comprises an
inner bush of predetermined shape mounted concentrically inside the outer bush. The
inner bush comprises, a first bonded metallic sleeve, a second metallic sleeve disposed
concentrically inside the first bonded metallic sleeve, wherein said second metallic sleeve
consists of a central longitudinal hole for mounting the bush to a rigid member, and a
rubber bonded in between the first bonded metallic sleeve and the second metallic sleeve,
wherein said rubber comprises two or more of voids predetermined shape to facilitate
variable stiffness in the inner bush.
In an embodiment of the present disclosure, the outer bush and the inner bush will have
different stiffness in two radial directions.
In an embodiment of the present disclosure, stiffness of the variable rate bush assembly is
varied by varying orientation of voids.
In an embodiment of the present disclosure, the inner bush is press fitted into the outer
bush.
Another embodiment of the present disclosure relates to a bush assembly. The bush
assembly comprises an outer bush of predetermined shape comprising a bonded metallic
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sleeve. A rubber is bonded to an inner circumference of the bonded metallic sleeve,
wherein said rubber comprises two or more of voids of predetermined shape to facilitate
variable stiffness in the outer bush and plurality of splines are formed on inner
circumference of the rubber. The bush further comprises an inner bush of predetermined
shape mounted concentrically inside the outer bush. The inner bush comprises, a metallic
sleeve comprising a central longitudinal hole for mounting the bush to a rigid member;
and a rubber bonded to an outer circumference of the metallic sleeve, wherein said rubber
comprises two or more voids of predetermined shape to facilitate variable stiffness in the
inner bush and plurality of grooves are formed on outer circumference of the rubber for
accommodating the splines.
In an embodiment of the present disclosure, shape of the splines formed on rubber of the
outer bush and grooves formed on rubber of the inner bush is selected from at least one of
dove tail shape, rectangular shape, square shape, circular shape and trapezoidal shape.
In an embodiment of the present disclosure, the inner bush is press fitted into the outer
bush.
In an embodiment of the present disclosure, the outer bush and the inner bush will have
different stiffness in two radial directions.
In an embodiment of the present disclosure, the stiffness of the variable rate bush
assembly is varied by varying orientation of voids.
The foregoing summary is illustrative only and is not intended to be in any way limiting.
In addition to the illustrative aspects, embodiments, and features described above, further
aspects, embodiments, and features will become apparent by reference to the drawings
and the following detailed description.
OBJECTIVES OF THE DISCLOSURE
One object of the present disclosure is to provide a variable rate bush assembly which has
non linear or variable stiffness in the same direction.
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One object of the present disclosure is to provide a variable rate bush assembly which has
a mechanism for changing the stiffness of the bush in different directions.
One object of the present disclosure is to provide a variable rate bush assembly for
suspension of a vehicle which caters to the requirement of the specific bush stiffness at
each location in the suspension.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended
claims. The disclosure itself, however, as well as a preferred mode of use, further
objectives and advantages thereof, will best be understood by reference to the following
detailed description of an illustrative embodiment when read in conjunction with the
accompanying figures. One or more embodiments are now described, by way of example
only, with reference to the accompanying figures wherein like reference numerals
represent like elements and in which:
FIG. 1 illustrates a perspective view of outer bush of the variable rate bush assembly.
FIG. 2 illustrates a perspective view of inner bush of the variable rate bush assembly.
FIGS. 3 and 4 illustrate perspective views of different arrangements of the variable rate
bush assembly according one embodiment of the present disclosure.
FIG. 5 illustrates a perspective view of splined outer bush of the bush assembly.
FIG. 6 illustrates a perspective view of grooved inner bush of the bush assembly.
FIGS. 7 and 8 illustrate perspective views of different arrangements of the splined bush
assembly according another embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One
skilled in the art will readily recognize from the following description that alternative
embodiments of the structures and methods illustrated herein may be employed without
departing from the principles of the disclosure described herein.
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DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present
disclosure in order that the detailed description of the disclosure that follows may be
better understood. Additional features and advantages of the disclosure will be described
hereinafter which form the subject of the claims of the disclosure. It should be
appreciated by those skilled in the art that the conception and specific embodiment
disclosed may be readily utilized as a basis for modifying or designing other structures
for carrying out the same purposes of the present disclosure. It should also be realized by
those skilled in the art that such equivalent constructions do not depart from the spirit and
scope of the disclosure as set forth in the appended claims. The novel features which are
believed to be characteristic of the disclosure, both as to its organization and method of
operation, together with further objects and advantages will be better understood from the
following description when considered in connection with the accompanying figures. It is
to be expressly understood, however, that each of the figures is provided for the purpose
of illustration and description only and is not intended as a definition of the limits of the
present disclosure.
To overcome the drawbacks mentioned in the background a variable rate bush assembly
is developed. The bush assembly can be fitted at different locations of suspension system
by varying the stiffness of the bush assembly.
FIGS. 1 and 2 are exemplary embodiments illustrating perspective views of outer bush
(101) and inner bush (103) of the variable rate bush assembly (100). The outer bush (101)
comprises a first bonded metallic sleeve (101a) of predetermined shape forming an outer
casing of the bush assembly (100). And a second metallic sleeve (101b) disposed
concentrically inside the first bonded metallic sleeve (101a). A rubber (101c) of
predetermined stiffness is bonded in between the first bonded metallic sleeve (101a) and
the second metallic sleeve (101b) facilitating damping in the bush assembly (100). The
rubber (101c) is provided with two or more voids (102) of predetermined shape to
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facilitate variable stiffness in the outer bush (101). Thus the outer bush (101) will have
different stiffness in two radial directions i.e. radial direction (A) and radial direction (B).
As shown in FIG. 2 the inner bush (103) comprises a first bonded metallic sleeve (103a)
of predetermined. And a second metallic sleeve (103b) disposed concentrically inside the
first bonded metallic sleeve (103a) forming inner casing of the bush assembly (100). The
second metallic sleeve (103b) consists of a central longitudinal hole (103d) for mounting
the bush assembly (100) to the vehicle chassis. The bush assembly (100) along with
suspension system is joined to the vehicle chassis using bolts. The inner bush (103)
further comprises a rubber (103c) of predetermined stiffness which is bonded in between
the first bonded metallic sleeve (103a) and the second metallic sleeve (103b) facilitating
damping in the bush assembly (100). The rubber (103d) is provided with two or more
voids (104) of predetermined shape to facilitate variable stiffness in the inner bush (103).
Thus the inner bush (103) will have two different stiffness in two radial directions i.e.
radial direction (A) and radial direction (B).
FIGS. 3 and 4 are exemplary embodiments illustrating perspective views of different
arrangements of the variable rate bush assembly according one embodiment of the
present disclosure. In the variable rate bush assembly (100) the inner bush (103) is
mounted concentrically inside the outer bush (101) by press fitting to form arrangement 1
of bush assembly (100) as shown in FIG. 3. In this arrangement the voids (102) of the
outer bush (101) and the voids (104) of the inner bush (103) are in-phase and thus
variable stiffness are embedded in the complete bush assembly (100). The stiffness in
each radial direction can be adjusted to the requirement by orienting the voids (102 and
104) by rotating inner bush (103) and outer bush (101) with respect to each other such
that the voids (102) of the outer bush (101) and the voids (104) of the inner bush (103)
are out of phase as shown in FIG. 4. There can be more than two voids (102 and 104) in
each inner bush (103) and outer bush (101) as per the requirement and both inner bush
(103) and outer bush (101) can be rotated with respect to each other to obtain different
stiffness in many radial directions as per the requirement of the vehicle. Thus the same
bush assembly (100) can be used in multiple locations without having to develop and use
another bush assembly (100) at different locations.
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In another embodiment of the present disclosure a variable rate bush (500) as shown in
FIG. 5 comprising splined outer bush (501) and grooved inner bush (504). FIGS. 5 and 6
are exemplary embodiments illustrating perspective views of splined outer bush (501)
and grooved inner bush (504) of the variable rate bush assembly (500).
As shown in FIG. 5 the splined outer bush (501) comprises a bonded metallic sleeve
(501a) of predetermined shape forming an outer casing of the bush assembly (500). A
rubber (501b) of predetermined stiffness is bonded to an inner circumference of the
bonded metallic sleeve (501a) facilitating damping in the bush assembly (500). The
rubber (501b) comprises two or more voids (502) of predetermined shape to facilitate
variable stiffness in the splined outer bush (501). Thus the outer bush (501) will have two
different stiffness in two radial directions i.e. radial direction (A) and radial direction (B).
The splined outer bush (501) further comprises plurality of splines (503) of
predetermined shape formed on inner circumference of the rubber (501b).
As shown in FIG. 6 the grooved inner bush (504) comprises a metallic sleeve (504a) of
predetermined shape forming an inner casing of the bush assembly (500). The metallic
sleeve (504a) is provided with central longitudinal hole (504b) for mounting the bush
(500) to the vehicle chassis The bush assembly (500) along with suspension system is
joined to the vehicle chassis using bolts. The grooved inner bush (504) further comprises
a rubber (504c) of predetermined stiffness is bonded to an outer circumference of the
metallic sleeve (501a) for facilitating damping in the bush assembly (500). The rubber
(504c) is provided with two or more voids (505) of predetermined shape to facilitate
variable stiffness in the inner bush (504). Thus the outer bush (501) will have two
different stiffness in two radial directions i.e. radial direction (A) and radial direction (B).
Further, a plurality of grooves (506) of predetermined shape are formed on outer
circumference of the rubber (504c) for accommodating the splines (503) formed on inner
circumference of the rubber (501b) of the splined outer bush (501).
In one aspect of the present disclosure, shape of the splines (503) formed on rubber
(501b) of the outer bush (501) and grooves (506) formed on rubber (504c) of the inner
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bush (504) is selected from at least one of dove tail shape, rectangular shape, square
shape, circular shape and trapezoidal shape such that the splines (503) rests inside the
groves (506) to make bush assembly (500).
FIGS. 7 and 8 are exemplary embodiments illustrating perspective views of different
arrangements of the splined bush assembly (500) according another embodiment of the
present disclosure. In the variable rate bush assembly (500) the grooved inner bush (504)
is mounted concentrically inside the splined outer bush (501) by press fitting to form
arrangement 1 [FIG. 7] of bush assembly (100). The splines (503) of the splined outer
bush (501) rests inside the groves (506) of the grooved inner bush (504) to make bush
assembly (500). In this arrangement the voids (502) of the splined outer bush (501) and
the voids (505) of the grooved inner bush (504) are in-phase and thus variable stiffness
are embedded in the complete bush assembly (500). Alternately splined outer bush (501)
can be oriented and spline fitted over grooved inner bush (504) to form arrangement 2 of
bush assembly (500). The stiffness in each radial direction can be adjusted to the
requirement by orienting and rotating splined outer bush (501) and grooved inner bush
(504) with respect to each other so that the voids (502) and voids (505) out of phase as
shown in FIG. 8. There can be more than two voids in each splined outer bush (501) and
grooved inner half bush (504) as per the requirement. And both splined outer bush (501)
and grooved inner half bush (504) can be rotated with respect to each other and
assembled to obtain different stiffness in many radial directions as per the requirement of
the vehicle. Washer (not shown) along with the bolt and the nut can be used to prevent
the relative axial motion between splined outer bush (501) and grooved inner bush (504).
Thus the same bush (500) can be used in multiple locations without having to develop
and use another bush at different locations.
In one aspect of the present disclosure, the variable rate bush assembly (100) or (500) as
explained above can be used to provide dampening in any machine which generates
vibration by connecting bush (100) or (500) to a rigid member and vibration isolator.
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Advantages:
The present disclosure provides a variable rate bush assembly for suspension of a vehicle
which caters to the requirement of the specific bush stiffness at each location in the
suspension.
The present disclosure provides a variable rate bush assembly which has a mechanism for
changing the stiffness of the bush in different directions.
The present disclosure provides a variable rate bush assembly which has non linear or
variable stiffness in the same direction.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those
having skill in the art can translate from the plural to the singular and/or from the singular
to the plural as is appropriate to the context and/or application. The various
singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and
especially in the appended claims (e.g., bodies of the appended claims) are generally
intended as "open" terms (e.g., the term "including" should be interpreted as "including
but not limited to," the term "having" should be interpreted as "having at least," the term
"includes" should be interpreted as "includes but is not limited to," etc.). It will be further
understood by those within the art that if a specific number of an introduced claim
recitation is intended, such an intent will be explicitly recited in the claim, and in the
absence of such recitation no such intent is present. For example, as an aid to
understanding, the following appended claims may contain usage of the introductory
phrases "at least one" and "one or more" to introduce claim recitations. However, the use
of such phrases should not be construed to imply that the introduction of a claim
recitation by the indefinite articles "a" or "an" limits any particular claim containing such
introduced claim recitation to inventions containing only one such recitation, even when
the same claim includes the introductory phrases "one or more" or "at least one" and
indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted
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to mean "at least one" or "one or more"); the same holds true for the use of definite
articles used to introduce claim recitations. In addition, even if a specific number of an
introduced claim recitation is explicitly recited, those skilled in the art will recognize that
such recitation should typically be interpreted to mean at least the recited number (e.g.,
the bare recitation of "two recitations," without other modifiers, typically means at least
two recitations, or two or more recitations). Furthermore, in those instances where a
convention analogous to "at least one of A, B, and C, etc." is used, in general such a
construction is intended in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C" would include but not be
limited to systems that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). In those instances where a
convention analogous to "at least one of A, B, or C, etc." is used, in general such a
construction is intended in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, or C" would include but not be
limited to systems that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). It will be further
understood by those within the art that virtually any disjunctive word and/or phrase
presenting two or more alternative terms, whether in the description, claims, or drawings,
should be understood to contemplate the possibilities of including one of the terms, either
of the terms, or both terms. For example, the phrase "A or B" will be understood to
include the possibilities of "A" or "B" or "A and B."
While various aspects and embodiments have been disclosed herein, other aspects and
embodiments will be apparent to those skilled in the art. The various aspects and
embodiments disclosed herein are for purposes of illustration and are not intended to be
limiting, with the true scope and spirit being indicated by the following claims.
Referral Numerals:
Reference Number Description
100 Variable rate bush assembly
101 Outer bush
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101a First bonded metallic sleeve of the outer bush
101b Second metallic sleeve of the outer bush
101c Rubber bonded between First bonded metallic sleeve and
second metallic sleeve of the outer bush
102 Voids in outer bush
103 Inner bush
103a First bonded metallic sleeve of the inner bush
103b Second metallic sleeve of the inner bush
103d Central longitudinal hole in the inner bush
103c Rubber bonded between First bonded metallic sleeve and
second metallic sleeve of the inner bush
104 Void in the inner bush
500 Variable rate splined bush assembly
501 Splined outer bush
501a Bonded metallic sleeve of the splined outer bush
501b Rubber bonded to inner circumference of the Bonded metallic
sleeve of the splined outer bush
502 Voids in splined outer bush
503 Splines formed on inner circumference of the rubber
504 Grooved inner bush
504a Metallic sleeve of the grooved inner bush
504b Central longitudinal hole in the grooved inner bush
504c Rubber bonded to outer circumference of the metallic sleeve of
the grooved inner bush
505 Voids in the grooved outer bush
506 Groves formed on the outer circumference of the rubber
A and B Radial directions
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We claim
1. A bush assembly (100) comprising:
an outer bush (101) of predetermined shape comprises;
a first bonded metallic sleeve (101a);
a second metallic sleeve (101b) disposed concentrically inside the
first bonded metallic sleeve (101a); and
a rubber (101c) bonded in between the first bonded metallic sleeve
(101a) and the second metallic sleeve (101b), wherein said rubber
comprises two or more voids (102) of predetermined shape to facilitate
variable stiffness in the outer bush (101);
an inner bush (103) of predetermined shape mounted concentrically inside
the outer bush (101), said inner bush (103) comprises;
a first bonded metallic sleeve (103a);
a second metallic sleeve (103b) disposed concentrically inside the
first bonded metallic sleeve (103a), wherein said second metallic sleeve
(103b) consists of a central longitudinal hole (103c) for mounting the bush
(100) to a rigid member; and
a rubber (103d) bonded in between the first bonded metallic sleeve
(103a) and the second metallic sleeve (103b), wherein said rubber (103d)
comprises two or more voids (104) of predetermined shape to facilitate
variable stiffness in the inner bush (103).
2. The variable rate bush assembly as claimed in claim 1, wherein the outer bush
(101) and the inner bush (103) will have different stiffness in two radial directions
(A and B).
3. The variable rate bush assembly as claimed in claim 1, wherein stiffness of the
variable rate bush assembly (104) is varied by varying orientation of voids (102
and 104).
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4. The variable rate bush assembly as claimed in claim 1, wherein the inner bush
(103) is press fitted into the outer bush (101).
5. A bush assembly (500) comprising:
an outer bush (501) of predetermined shape comprises;
a bonded metallic sleeve (501a);
a rubber (501b) bonded to an inner circumference of the bonded
metallic sleeve (501a), wherein said rubber (501b) comprises two or more
of voids (502) of predetermined shape to facilitate variable stiffness in the
outer bush (501) and plurality of splines (503) are formed on inner
circumference of the rubber (501b);
an inner bush (504) of predetermined shape mounted concentrically inside
the outer bush (501), said inner bush (504) comprises;
a metallic sleeve (504a) comprising a central longitudinal hole
(504b) for mounting the bush (500) to a rigid member; and
a rubber (504c) bonded to an outer circumference of the metallic
sleeve (501a), wherein said rubber (504c) comprises two or more voids
(505) of predetermined shape to facilitate variable stiffness in the inner
bush (504) and plurality of grooves (506) are formed on outer
circumference of the rubber (504c) for accommodating the splines (503).
6. The variable rate bush assembly as claimed in claim 5, wherein shape of the
splines (503) formed on rubber (501b) of the outer bush (501) and grooves (506)
formed on rubber (504c) of the inner bush (504) is selected from at least one of
dove tail shape, rectangular shape, square shape, circular shape and trapezoidal
shape.
7. The variable rate bush assembly as claimed in claim 5, wherein the inner bush
(504) is press fitted into the outer bush (501).
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8. The variable rate bush assembly as claimed in claim 5, wherein the outer bush
(501) and the inner bush (504) will have different stiffness in two radial directions
(A and B).
9. The variable rate bush assembly as claimed in claim 5, wherein the stiffness of the
variable rate bush assembly (500) is varied by varying orientation of voids (502
and 505).