U.S. patent application number 10/789689 was filed with the patent office on 2004-10-14 for stopper structure for engine mount.
This patent application is currently assigned to TOKAI RUBBER INDUSTRIES, LTD.. Invention is credited to Andou, Tetsuji, Okanaka, Takehiro.
Application Number | 20040201150 10/789689 |
Document ID | / |
Family ID | 33119143 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040201150 |
Kind Code |
A1 |
Okanaka, Takehiro ; et
al. |
October 14, 2004 |
Stopper structure for engine mount
Abstract
A stopper structure including: a rigid abutting member extending
in its longitudinal direction with a rectangular cross sectional
shape; and a rubber stopper having a base portion of tubular cross
sectional shape and secured press-fit onto the rigid abutting
member without being adhesive thereto, two peripheral projections
formed on laterally opposite sides of a first abutting plane of the
base portion and extending in the longitudinal direction, and a
central projection formed on an intermediate area interposed
between the peripheral projections of the first abutting plane of
the base portion. The peripheral projections are situated above
laterally opposite corners of a first abutting plane of the rigid
abutting member, and have a width dimension extending inside and
outside the corners. The central projection projects outward from
the first abutting plane of the base portion with a height smaller
than that of the peripheral projections.
Inventors: |
Okanaka, Takehiro;
(Kasugai-shi, JP) ; Andou, Tetsuji; (Inuyama-shi,
JP) |
Correspondence
Address: |
BEYER WEAVER & THOMAS LLP
P.O. BOX 778
BERKELEY
CA
94704-0778
US
|
Assignee: |
TOKAI RUBBER INDUSTRIES,
LTD.
|
Family ID: |
33119143 |
Appl. No.: |
10/789689 |
Filed: |
February 27, 2004 |
Current U.S.
Class: |
267/140.11 |
Current CPC
Class: |
F16F 13/101 20130101;
F16F 13/108 20130101 |
Class at
Publication: |
267/140.11 |
International
Class: |
F16F 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2003 |
JP |
2003-055017 |
Claims
What is claimed is:
1. A stopper structure for an engine mount including an elastic
body elastically connecting two mounting members, the stopper
structure comprising: a rigid abutting member connected to one of
the two mounting members, and extending in a longitudinal direction
with a substantially rectangular shape in cross section; and a
rubber stopper including: a base portion of tubular shape in cross
section, and being secured press-fit onto the rigid abutting member
without being adhesive to an superficial surface of the rigid
abutting member; a pair of peripheral projections formed on
laterally opposite sides of a first abutting plane of the base
portion and extending in the longitudinal direction of the rigid
abutting member; and at least one central projection formed on an
intermediate area interposed between the pair of peripheral
projections of the first abutting plane surface of the base
portion, wherein the pair of peripheral projections are situated
above laterally opposite corners of a corresponding first abutting
plane of the rigid abutting member, respectively, and have a width
dimension extending inside and outside the corners of the rigid
abutting member, and wherein the at least one central projection
projects outward from the first abutting plane of the base portion
with a height dimension smaller than that of the pair of peripheral
projections.
2. A stopper structure according to claim 1, wherein the base
portion has a wall thickness dimension larger than the height
dimension of the pair of peripheral projections.
3. A stopper structure according to claim 1, wherein the first
abutting plane of the base portion is brought into abutting contact
with an abutting portion provided by a member connected to an other
one of the two mounting member, upon application of a vibrational
load to the engine mount in a bound direction.
4. A stopper structure according to claim 1, wherein a direction in
which the rubber stopper is inserted onto the rigid abutting member
to be secured press fit thereon is conform to the longitudinal
direction in which the pair of peripheral projections extend.
5. A stopper structure according to claim 1, wherein the at least
one central projections comprises a plurality of central
projections, and the plurality of central projections arranged in
at least one straight line extending parallel to the pair of
peripheral projections.
6. A stopper structure according to claim 1, wherein the at least
one of the central projection is situated inside the laterally
opposite corners of the first abutting plane of the rigid abutting
member in the lateral direction.
7. A stopper structure according to claim 1, wherein each of the
pair of peripheral projections provides substantially flat abutting
surfaces on a top thereof, and the at least one central projection
has a cone-like shape.
8. A stopper structure according to claim 1, wherein the stopper
structure is arranged for a hanging type engine mount for
automotive vehicles, the other one of the mounting members is
connected to a body of the vehicle, and the rigid abutting member
comprises an connector arm disposed below the engine mount and
connected to the one of the two mounting members in order to hang a
power unit from the one of the two mounting members, and wherein
the first abutting plane of the base portion of the rubber stopper
is brought into abutting contact with an abutting portion provided
on the body of the vehicle upon application of a vibrational load
to the engine mount in a bound direction.
Description
INCORPORATED BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2003-055017 filed on Feb. 28, 2003 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to stopper
structures for engine mounts, more particularly to such a stopper
structure in which a rubber stopper formed independently and
secured press-fit onto an abutting member connected to one of two
mounting members of an engine mount, without being adhesive to a
superficial surface of the abutting member.
[0004] 2. Description of the Related Art
[0005] An engine mount has been widely used for elastically
mounting or hanging a power unit of an automotive vehicle on or
from a body of the vehicle in a vibration damping fashion.
Generally, such an engine mount includes a rubber elastic body
elastically connecting a first mounting member fixable to the power
unit, a second mounting member fixable to the body of the vehicle,
and an elastic body elastically connecting the first and second
mounting members. In the engine mount, a stopper structure is
incorporated to limit excess displacement between the first and
second mounting members in a direction of vibration input, by
bringing an abutting portion connected to the first mounting member
into abutting contact with the other abutting portion connected to
the second mounting member, or vice versa. The stopper structure
includes a rubber stopper for cushioning an impact and/or noise
upon abutment of the abutting portions against each other.
[0006] FIG. 13 shows an example of conventional engine mount 200 of
fluid-filled type. The engine mount 200 includes a mount body 201
that is mounted to a vehicle body (not shown) via a mounting
bracket 203.
[0007] The mounting bracket 203 includes a holding portion 209 of
cup shape having a bottom 205, and a fixing portion 215 having a
pair of legs 211, 211 and a sheet 213 by which the legs 211, 211
are connected together, and on which the bottom 205 of the holding
portion 209 is received. The holding portion 209 holds the mount
body 201 in a press-fit manner, and the fixing portion 215 is
fastened at distal ends of the legs 211, 211 to the body of the
vehicle, by means of suitable fastening members.
[0008] As shown in FIG. 13, a connector arm 217, which is disposed
on the side of the power unit, is inserted into a space 219 defined
between the pair of legs 211, 211 and situated below the holding
portion 209, and is connected to a mounting shaft 216 of a first
mounting member 208 of the mount body 201.
[0009] A rubber stopper 221 has an overall rectangular tubular
shape corresponding to a transverse cross sectional view of the
connector arm 217, and is secured press fit onto an outer surface
of the connector arm 217 in a non-adhesion manner, such that the
connector arm 217 is elastically inserted into the rubber stopper
221.
[0010] An upper portion 221A of the rubber stopper 221 is brought
into abutting contact with an abutting portion 223 of the mounting
bracket 203, and an lower portion 221B of the rubber stopper 221 is
brought into abutting contact with an abutting portion 227 of a
sub-frame 229 of the body. With this arrangement, a relative
displacement between the first and second mounting members 208 and
209 in the vertical direction is suitably limited. In the rubber
stopper 221, the upper portion 221A as well as the lower portion
221B are formed with a flat plate configuration having a
substantially constant wall thickness over an entire widthwise
direction.
[0011] Keeping pace with a recent tendency of upgrading quietness
in vehicles, there is an increasing demand for rubber stoppers of
stopper structures, like the rubber stopper 221, to enhance its
shock absorbing performance while maintaining its durability.
[0012] The desired durability of the rubber stopper 221 may be
obtained by forming it with the flat-plate shape having a thin and
substantially constant wall thickness as shown in FIG. 13. Namely,
this arrangement permits that a surface pressure acting on the
rubber stopper 221 during its abutting contact against the abutting
portions 213, 227, evenly distributes over a wide area of the
rubber stopper 221. Therefore, the rubber stopper 221 is free from
a local considerable deformation or a local stress concentration,
leading to an enhanced durability of the rubber stopper 221.
[0013] However, this arrangement gives the rubber stopper 221
undesirable load-deformation characteristics (i.e. spring
characteristics recognized in a two dimensional graph) which is
skyrocketed at the initial stage of the abutting contact of the
rubber stopper 221 against the abutting portions 213, 227.
[0014] Alternatively, it may be proposed for ensuring the desired
durability of the rubber stopper 221 to provide local abutting
portions on the abutting surface of the rubber stopper 221. This
makes a feeling of touch of the rubber stopper 221 against each of
the abutting portions 213, 227 soft, permitting the rubber stopper
221 to provide a soft stopper performance. However, the local
abutting portions are likely to suffer from a relatively large
deformation and stress, leading to earlier damages and
deteriorations of the local abutting portions, resulting in a low
durability and a short lifetime of the rubber stopper 221.
JP-A-9-166175 and JP-A-2001-349368 disclose examples of
conventional rubber stoppers used in stopper structures in engine
mounts of hanging type.
[0015] The conventional stopper structure as disclosed in the
aforesaid documents may suffer from stress concentration at
laterally opposite edge portions of upper and lower portions 221A
and 221B, which portions are pressed onto corresponding corners of
the connector arm 217. Namely, when the upper and lower portions
221A and 221B of the rubber stopper 221 are brought into abutting
contact with the abutting portions 213, 227, respectively, the
laterally opposite edge portions of the upper and lower portions
221A and 221B is very likely to undergo outward elastic deformation
along the superficial profile of the connector arm 217. With this
state, the corners provide resistance to the outward elastic
deformation of the laterally opposite edge portions, thus
generating stress concentration at the laterally opposite edge
portions. This results in cracks or other damages of the rubber
stopper 221 at the edge portions, thus deteriorating durability of
the rubber stopper 221 and the stopper structure.
[0016] As is understood from the foregoing description, the
durability and the soft stopper performance of the rubber stopper
221 are contradictory to each other, and it has not yet developed a
rubber stopper capable of exhibiting both of a desired durability
and soft stopper performance.
SUMMARY OF THE INVENTION
[0017] It is therefore one object of this invention to provide a
stopper structure for an engine mount for automotive vehicles,
which is capable of exhibiting a sufficient durability, and a soft
stopper performance, as well.
[0018] The above and/or other objects of this invention may be
attained according to at least one of the following modes of the
invention. Each of these modes of the invention is numbered like
the appended claims and depending from the other mode or modes,
where appropriate, to indicate possible combinations of elements or
technical features of the invention. It is to be understood that
the principle of the invention is not limited to these modes of the
invention and combinations of the technical features, but may
otherwise be recognized based on the teachings of the present
invention disclosed in the entire specification and drawings or
that may be recognized by those skilled in the art in the light of
the present disclosure in its entirety.
[0019] A first mode of the invention is a stopper structure for an
engine mount including an elastic body elastically connecting two
mounting members, and stopper structure comprising: (a) a rigid
abutting member connected to one of the two mounting members, and
extending in a longitudinal direction with a substantially
rectangular shape in cross section; and (b) a rubber stopper
including: a base portion of tubular shape in cross section, and
being secured press-fit onto the rigid abutting member without
being adhesive to a superficial surface of the rigid abutting
member; a pair of peripheral projections formed on laterally
opposite sides of a first abutting plane of the base portion and
extending in the longitudinal direction of the rigid abutting
member; and at least one central projection formed on an
intermediate area interposed between the pair of peripheral
projections of the first abutting plane of the base portion,
wherein the pair of peripheral projections are respectively
situated above laterally opposite corners of a corresponding first
abutting plane of the rigid abutting member, respectively, and have
a width dimension extending inside and outside the corners of the
rigid abutting member, and wherein the at least one central
projection projects outward from the first abutting plane of the
base portion with a height dimension smaller than that of the pair
of peripheral projections.
[0020] According to this mode of the invention, the rubber stopper
includes the pair of peripheral projections and the at least one
central projection, which are formed on respective portions of the
base portion separately from each other, and project outwardly from
the base portion with different height dimensions, respectively.
This arrangement permits the two kinds of projections to share
functions required for rubber stoppers for engine mounts, i.e.,
durability and soft stopper performance, in an efficient manner.
Described in detail, the pair of peripheral projections are
situated above the laterally opposite corners of the corresponding
first abutting plane of the rigid abutting member, and have a
sufficient width extending inside and outside the respective
corners, as well as a sufficient height or thickness. With the help
of the peripheral projections overlapping the laterally opposite
corners of the first abutting plane of the rigid abutting member,
is prevented a conventionally experienced excess outward
displacement or elastic deformation of the peripheral portion of
the first abutting plane of the base portion of the rubber stopper
along an superficial profile of the rigid abutting member, when the
first abutting plane of the rubber stopper is brought into abutting
contact with an abutting surface provided on a member connected to
the other one of the two mounting member. Accordingly, the rubber
stopper is less likely to suffer from or free from a
stress-concentration at a local area pressed onto the corners of
the first abutting plane of the rigid member, and a resultant
cracking or other defects due to the stress concentration.
Therefore, the rubber stopper having the pair of peripheral
projections of aforesaid unique structure can enhance durability
thereof, and resultant durability of the stopper structure.
[0021] On the other hand, the central projection is formed with a
height dimension smaller than that of the pair of peripheral
projections. This arrangement enables the rubber stopper to exhibit
a non-linear spring characteristic as show in the graph of FIGS.
9D, which is required for an engine mount. As is understood from
the aforesaid description, the combination use of the pair of
peripheral projections and at least one central projection makes it
possible for the stopper structure to exhibit a desired durability
thereof, and desired soft stopper performance, concurrently.
[0022] Namely, when employing only the pair of peripheral
projections, the rubber stopper is not able to sufficiently absorb
a shock during operation of the stopper structure, and when
employing only the central projections, the rubber stopper is not
able to ensure a sufficient durability due to inevitable excess
elastic deformation of the central projections. In addition, the
latter rubber stopper can exhibit soft stopper performance at an
initial stage in the course of abutting contact of the central
projection against the abutting portion, but may still suffer from
an abrupt increase in resistance to deformation thereof, once an
amount of elastic deformation of the central projection reaches a
predetermined threshold level.
[0023] According to the present invention, the use of the central
projection together with the pair of peripheral projections can
eliminates a shock during operation of the stopper structure, which
may be generated in the rubber stopper having only the pair of
peripheral projections. Also, the use of the peripheral projection
together with the central projection can eliminate a conventional
problem of low durability due to damage of the central peripheral
projection, which may be generated in the rubber stopper having
only the central projections. Thus, the stopper structure
constructed according to the present invention can exhibit both of
an excellent stopper characteristics and sufficient durability,
concurrently.
[0024] It should be noted that, the number of central projections
is not particularly limited, and may be desirably changed depending
upon required spring and/or stopper characteristics of the rubber
stopper. Likewise, each of the peripheral projection may have a
desirable form, provided the peripheral projection situated above
and has a width extending inside and outside the corresponding
corner of the rigid abutting member, while extending
longitudinally. It should also be noted that the rigid abutting
member includes a member formed independently of the one mounting
member and then connected to the mounting member, and a member
integrally formed with the one mounting member.
[0025] A second mode of the invention is a stopper structure
according to the first mode, wherein the base portion has a wall
thickness dimension larger than the height dimension of the at
least one central projection. According to this arrangement, a
further enhanced durability of the rubber stopper can be achieved.
For use in a fluid-filled engine mount of hanging type, the rubber
stopper may preferably be designed such that the base portion has a
thickness A of 4.5-8 mm, the peripheral projections has the height
dimension B of 3-5 mm, and the central projection has the height
dimension C of 1.5-3 mm, and three factors A, B and C meets the
following inequality: A>B>C.
[0026] A third mode of the invention is a stopper structure
according to the first or second mode, wherein the first abutting
plane of the rubber stopper is brought into abutting contact with
an abutting portion provided by a member connected to an other one
of the two mounting member, upon application of an excess load to
the engine mount in a bound direction. With this arrangement, the
stopper structure can provide a bound stopper, and exhibits
excellent stopper performance with respect to the excess input load
in the bound direction. It should be appreciated that the member
providing the abutting portion includes a member formed
independently of the other mounting member, and a member integrally
formed with the other mounting member.
[0027] A fourth mode of the invention is a stopper structure
according to any one of the first through third modes, wherein a
direction in which the rubber stopper is inserted onto the rigid
abutting member to be secured press fit thereon is conform to the
longitudinal direction in which the pair of peripheral projections
extend. This arrangement makes it easy to insert the rubber stopper
onto the rigid abutting member.
[0028] A fifth mode of the invention is a stopper structure
according to any one of the first through fourth modes, wherein the
at least one central projections comprises a plurality of central
projections, and the plurality of central projections arranged in
at least one straight line extending parallel to the pair of
peripheral projections.
[0029] A sixth mode of the invention is a stopper structure
according to any one of the first to fifth modes, wherein the
central projection is situated inside the laterally opposite
corners of the first abutting plane of the base portion of the
rigid abutting member in the lateral direction. With this
arrangement, the central projection is free from damages due to
stress concentration caused by the corners of the rigid abutting
member.
[0030] A seventh mode of the invention is a stopper structure
according to any one of the first through sixth modes, wherein each
of the pair of peripheral projections provides substantially flat
abutting surfaces on a top thereof, and the at least one central
projection has a cone-like shape. According to this arrangement,
the peripheral projections can receive a load applied to thereto
with a relatively wide area, thereby further ensuring durability of
the rubber stopper as well as the stopper structure. On the other
hand, the central portion is suitably configured to exhibit a
desired non-linear spring characteristics or a soft stopper
performance, thus further absorbing a shock during operation of the
stopper structure.
[0031] A eighth mode of the invention is a stopper structure
according to any one of the first through sixth modes, wherein the
stopper structure is arranged for a hanging type engine mount for
automotive vehicles, the other one of the mounting members is
connected to a body of the vehicle, and the rigid abutting member
comprises a connector arm disposed below the engine mount and
connected to the one of the two mounting members in order to hang a
power unit from the one of the two mounting members, and wherein
the first abutting plane of the base portion of the rubber stopper
is brought into abutting contact with an abutting portion provided
on the body of the vehicle upon application of an excess load to
the engine mount in a bound direction. According to this mode, the
present stopper structure can be installed in the hanging type
fluid-filled engine mount with high space utilization. It should be
appreciated that the stopper structure can provide a rebound
stopper on the opposite side from the first abutting plane in a
bound/rebound load input direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The foregoing and/or other objects features and advantages
of the invention will become more apparent from the following
description of a preferred embodiment with reference to the
accompanying drawings in which like reference numerals designate
like elements and wherein:
[0033] FIG. 1 is a vertical cross sectional view of a stopper
structure constructed according to the present invention, which is
installed in a fluid-filled engine mount of hanging type.
[0034] FIG. 2 is a perspective view showing a state where a rubber
stopper of FIG. 1 is installed in the engine mount of FIG. 1;
[0035] FIG. 3 is an exploded perspective view suitable for
explaining an installation of the rubber stopper into the engine
mount of FIG. 1;
[0036] FIG. 4 is a vertical cross sectional view of a mount body of
the engine mount of FIG. 1;
[0037] FIG. 5 is an exploded perspective view of the mount body of
FIG. 4;
[0038] FIG. 6 is an exploded vertical cross sectional view of the
mount body of FIG. 4;
[0039] FIGS. 7A and 7B are perspective views solely show a rubber
stopper of the invention;
[0040] FIG. 8A is a bottom elevational view of a rubber stopper,
FIG. 8B is a cross sectional view taken along line B-B of FIG. 8A,
and FIG. 8C is a cross sectional view taken along line C-C of FIG.
8A;
[0041] FIG. 9D is a graph demonstrating spring characteristics of
rubber stopper constructed according to the present invention, and
FIGS. 9A-9C are graphs demonstrating spring characteristics of
comparative examples of rubber stoppers;
[0042] FIGS. 10A and 10B are graphs demonstrating spring
characteristics of other comparative examples of rubber
stoppers;
[0043] FIGS. 11A-11D are schematic illustrations of principle parts
of comparative examples exhibiting spring characteristics shown in
FIGS. 9A-9C, respectively;
[0044] FIG. 12A is a fragmental schematic cross sectional view of
the rubber stopper of the present invention, and FIG. 12B is a
schematic bottom plane view of the rubber stopper of the present
invention;
[0045] FIGS. 13A is a fragmental schematic cross sectional view of
the rubber stopper having spring characteristics shown in graph of
FIG. 10A, and FIG. 13B is a schematic bottom plane view of this
rubber stopper;
[0046] FIG. 14A is a fragmental schematic cross sectional view of
the rubber stopper having spring characteristics shown in graph of
FIG. 10B, and FIG. 14B is a schematic bottom plane view of this
rubber stopper; and
[0047] FIG. 15 is a vertical cross sectional view of an example of
a conventional fluid-filled engine mount having a stopper structure
using a conventional rubber stopper.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0048] Referring first to FIGS. 1-3, there is shown a fluid-filled
engine mount 10 of hanging type including a mount body 11, a
mounting bracket 13 for mounting the mount body 11 on a body of the
vehicle (not shown).
[0049] The mounting bracket 13 includes a holding portion 19 having
a cup shaped part 17 and a bottom 15, and a fixing portion 25
having a pair of legs 21, 21 and a sheet 23 by which the legs 21,
21 are connected together, and on which the bottom 15 of the
holding portion 19 is received. The holding portion 19 holds the
mount body 11 in a press-fit manner, and the fixing portion 25 is
fastened at distal ends of the legs 21, 21 to a member on the body
side, e.g., a sub frame 49 of the vehicle.
[0050] An abutting member in the form of a connector arm 29 is a
member disposed on a side of a power unit, and is inserted into a
space 39 defined between the pair of legs 21, 21 and situated below
the holding portion in an axis direction thereof. The connector arm
29 is connected to a mounting shaft 28 of the mount body 11 by
means of a bolt or other fastening members.
[0051] A rubber stopper 41 has an overall rectangular tubular shape
corresponding to a transverse cross sectional view of the connector
arm 29, and is press-fit onto a superficial surface of the
connector arm 29 in a non-adhesive manner. The rubber stopper 41 is
brought into abutting contact against an abutting surface 45 of the
mounting bracket 13, and an abutting surface 47 of the sub frame
49, so as to limit an amount of relative displacement between a
first mounting member in the form of an inner shaft member 20 and a
second mounting member in the form of an outer sleeve member 18 of
the mount body 11, in the vertical direction as seen in FIG. 1.
[0052] FIGS. 4-6 show the mount body 11 more detail. The mount body
11 includes the inner shaft member 20 made of rigid metal, the
outer sleeve member 18 formed of a tubular rigid metal, and a
rubber elastic body 22 elastically connecting the inner shaft
member 20 and the outer sleeve member 18. A lid member 14, and an
intermediate partition member 16 are superposed on and fixed to an
upper open end of the mount body 11, in order to close the opening
of the mount body 11.
[0053] The inner shaft member 20 includes an upper cup-shaped
portion 24 having a flange portion extending diametrically
outwardly, and a lower shaft portion 28 having a tapped bore 26. As
shown in FIG. 1, the mount body 11 is fixable at the inner shaft
member 20 to a power unit of the vehicle via the connector arm 29.
Also, the mount body 11 is fixable at the outer sleeve member 18 to
the body of the vehicle via the mounting bracket 13. With this
arrangement, the power unit is supported by the body of the vehicle
in a hanging state.
[0054] FIG. 4 shows a state where no power unit is hanged from the
mount body 11, and FIG. 1 shows an engine hanging state where the
power unit is hanged from the mount body 11 that is fixed to the
body of the vehicle 49.
[0055] The rubber elastic body 22 is a member of substantially
truncated conical configuration, and is disposed about the inner
shaft member 20 with a substantially annular configuration. More
specifically, the rubber elastic body 22 extends diametrically
diagonally between an tapered portion 34 of the outer sleeve member
18 and an upper portion of the inner shaft member 20, which extends
from an upper end portion of the mounting shaft 28 to a rim of the
flange portion, thereby elastically connecting the inner shaft
member and the outer sleeve member 18, respectively.
[0056] The upper open end of the mount body 11 is closed by the lid
member 14 with a fluid-tight sealing, thereby forming a fluid tight
area defined within the mount body 11. This fluid-tight area is
filled with a non-compressible fluid L, such as water, alkylene
glycol, polyalkylene glycol, silicone oil and others, thereby
providing a fluid chamber. A low viscosity fluid having a viscosity
of 0.1 Pa.s. or lower is preferably selected.
[0057] This fluid chamber is divided into two parts by means of the
partition member 16, namely, a pressure receiving chamber 34 on the
lower side of the partition member 16, and an auxiliary fluid
chamber 36 on the upper side of the partition member 16. The
partition member 16 includes an annular rigid partition plate 38
made of metal. The partition plate 38 is laminated at its outer rim
portion on a shoulder portion 39 of the outer sleeve member 18, and
is firmly fixed to the outer sleeve member 18 by pressingly bending
a caulking portion 40 of the outer sleeve member 18 against the
outer rim portion in the process of caulking fixation. Thus, the
partition plate 38 is integrally bonded to the outer sleeve member
18.
[0058] In the present embodiment, the partition plate 38 is a
metallic plate formed by press-bending, having a wall thickness of
1 mm.
[0059] The partition plate 38 has a large-diameter opening 42 that
is fluid-tightly closed by a movable layer 44. The movable layer 44
is formed of a rubber elastic body and integrally bonded to the
partition plate 38 in the process of vulcanization of a rubber
material for forming the movable layer 44. The movable layer 44
undergoes elastic deformation in the vertical direction as seen in
FIG. 1, thereby absorbing a fluid pressure variation induced in the
pressure receiving chamber 34. The lid member 14 includes flexible
diaphragm 43 and cooperate with the partition member 16 to define
therebetween the auxiliary fluid chamber 36.
[0060] The partition plate 38 and the lid member 14 cooperate to
each other to define therebetween an orifice passage 46 extending
circumferentially at their outer peripheral portions. One of
opposite ends of the orifice passage 46 is held in communication
with the pressure receiving chamber 34 through a first
communication hole 48, and the other one of opposite ends of the
orifice passage 46 is held in fluid communication with the
auxiliary fluid chamber 36, whereby the fluid L can flow through
the orifice passage 46 between the pressure receiving chamber and
the auxiliary fluid chamber 36.
[0061] As is apparent from FIGS. 4 and 5, the first and second
communication holes are situated adjacent to each other so that the
orifice passage 46 can extend circumferentially with a
circumferential length slightly smaller than a circumference of the
partition member 16. In the present embodiment, a rubber block 52
is integrally bonded on the partition plate 38 together with the
movable plate 44 in the process of vulcanization of a rubber
material for forming the rubber block 52. As shown in FIGS. 4 and
5, this rubber block 52 includes a cutout portion 54 at one
circumferential position, whereby the second communication hole 50
is formed by utilizing this cutout portion 54 of the rubber block
52.
[0062] While the orifice passage 46 is defined between the outer
peripheral portions of the lid member 14 and the partition member
16 as discussed above, a metallic core member 56 of plate shape is
embedded within the outer peripheral portion of the lid member 14,
as shown in FIG. 4. The core member 56 is firmly fixed to the outer
sleeve member 18 together with the partition plate 38 by bending
the caulking portion 40 against thereto, in the process of
aforementioned caulking fixation (see FIG. 4).
[0063] The fluid-filled engine mount 10 constructed as described
above, is capable of effectively damping input vibrations, through
an energy absorption on the basis of viscous flow of the fluid L
through the orifice passage 46 between the pressure receiving
chamber 34 and the auxiliary fluid chamber 36, when subjected to
low frequency vibrations applied thereto in the vertical direction.
This damping performance is most excited at a frequency band in
which resonance effect of the fluid L through the orifice passage
46 is exhibited. In the present embodiment, the orifice passage 46
is tuned so that resonance of the fluid flowing through the orifice
passage 46 is generated at a frequency band of engine shake
vibrations, i.e., within a range of 10-20 Hz.
[0064] When the frequency of the input vibration higher than the
frequency band to which the orifice passage 46 is tuned, a
resistance to flow of the fluid through the orifice passage 46
tends to be increased, resulting in a substantially closed state of
the orifice passage 46. In this state, the movable layer 44 is
forced to elastically displaced or deformed back and force in the
vertical direction in accordance with fluid pressure variation
induced in the pressure-receiving chamber 34, whereby the fluid
pressure variation induced in the pressure-receiving chamber 34 can
be absorbed by the elastic displacement of the movable layer
34.
[0065] Referring back to FIG. 1, the tubular rubber stopper 41 has
a base portion of tubular or rectangular shape in cross section.
The rubber stopper 41 is illustrated in detail in FIGS. 7 and 8.
The base portion of the rubber stopper 41 includes a pair of
sidewall portions 70, 70, a top wall portion 72, and a bottom wall
portion 74 functioning as a first abutting plane of the base
portion of the rubber stopper 41. The top and bottom wall portions
72, 74 have circular through holes 76A, 76B, respectively. The
through hole 76A in the top wall portion 72 is formed for
permitting insertion of the shaft member 28 extending therethrough,
as shown in FIG. 1. On the other hand, the through hole 76B in the
bottom wall portion 74 is formed for permitting an insertion of a
mounting bolt and for providing a working space for fastening the
mounting bolt into the mounting shaft 28.
[0066] The pair of sidewall portions 70, 70 and the top wall
portions 72 are flat plate members with a substantially constant
wall thickness, and provide stopper performance. When the connector
arm 29 undergoes excess displacement in the lateral direction as
seen in FIG. 1, the sidewall portions 70, 70 are brought into
elastic contact against the mounting bracket 13 so as to limit an
amount of lateral displacement of the connector arm 29. When the
connector arm 29 undergoes excess displacement in the upward
direction as seen in FIG. 1, i.e., a rebound direction, the top
wall portion 72 is brought into elastic contact against the
mounting bracket 13 so as to limit an amount of upward displacement
of the connector arm 29. Likewise, the bottom wall portion 74
provides a stopper performance, when coming into elastic contact
against the abutting portion 47 as a result of an excess
displacement of the connector arm 29 in the downward direction as
seen in FIG. 1, i.e., in a bound direction.
[0067] However, the bottom wall portion 74, i.e., the first
abutting plane, has a unique configuration. Namely, the bottom wall
portion 74 includes a central projection in the form of an elastic
base 74A having a substantially uniform or constant wall thickness
in the lateral direction, and a pair of peripheral projections 82,
82 as well as a plurality of central projections 84 projecting
outward or downward from the elastic base 74A. The pair of
peripheral projections 82, 82 of bar-like shape are situated at
laterally opposite sides, i.e., the opposite sides in the widthwise
direction of the elastic base 74A, and continuously straightly
extending in a longitudinal direction of the connector arm 29,
along with laterally opposite rims of the elastic base 74,
respectively. The plurality of central projections 84 have a
part-spherical shape.
[0068] The plurality of central projections 84 are formed
independently from one another, and are situated spaced away from
one another. More specifically, each central projection 84 has a
cone-like shape, and is spaced apart from another central
projections 84 at least at its apex portion. Each of the plurality
of central projections 84 has a height dimension smaller than that
of the pair of peripheral projections 82, and all of the plurality
of central projections 84 have the same dimension in their
projection height as measured from the elastic base 74A.
[0069] As mentioned above, each of the central projections 84, has
a part-spherical configuration, and a cone shape in cross section.
On the other hand, the peripheral projections 82, as shown in FIG.
8B, provide a substantially flat abutting surfaces 82A, 82A.
[0070] As shown in FIGS. 1 and 8, each of the surfaces 82A has a
width dimension, i.e., a dimension measured in the lateral
direction in FIG. 1, slightly larger than does the corresponding
sidewall portion 70 of the rubber stopper 41. The inside edge of
each abutting surface 82A is situated inward of the corresponding
one of laterally opposite corners of a first abutting plane of the
connector arm 29. The central projections 84 are all situated
within inward of the abutting surfaces 82A of the peripheral
projections 82 so that the all central projections 84 are situated
inward of the laterally opposite corners of the first abutting
plane of the connector arm 29.
[0071] In the present embodiment, eight central projections 84 are
formed on an intermediate area interposed between the pair of
peripheral projections 82, 82 on the bottom wall portion 74. Four
of the eight central projections 84 are arranged on the left-hand
side of the bottom wall portion 74 in an alignment on a straight
line extending parallel to the inside edge of the left side
abutting surface 82A, while the other four central projections 84
are similarly arranged on the right-hand side of the bottom wall
portion 74 in an alignment on a straight line extending parallel to
the inside edge of the right side abutting surface 82A. A variety
of pattern of arrangement of the abutting surfaces 82A may be
desirably employed, and the present invention is not particularly
limited to the pattern illustrated in this embodiment. For
instance, the abutting surfaces 82A may be formed more dispersedly
than does the present embodiment.
[0072] According to the present embodiment, the peripheral
projections 82 and the central portions 84 effectively share
functions required for rubber stoppers, whereby the rubber stopper
41 can exhibit a required durability and soft stopper performance
as well.
[0073] In the case where a rubber stopper has an abutting portion
constituted by the peripheral projection 82 entirely, for example,
it is difficult for the rubber stopper to absorb a shock upon
abutting contact of the rubber stopper against the sub frame 49. In
the case where a rubber stopper has an abutting portion constituted
by the central projection 84 entirely, the central projection 84
may undergo excess elastic deformation upon abutting contact of the
rubber stopper against the mounting bracket 13, resulting in an
insufficient durability of the rubber stopper. In the latter case,
additionally, the central projection 84 can exhibit soft stopper
performance at an initial stage of an abutting action of the rubber
stopper against the sub frame 49, but may suffer from an abrupt
increase in resistance to deformation thereof, once an amount of
elastic deformation of the central projections 84 reaches a
predetermined threshold level.
[0074] With this respect, the rubber stopper 41 of the present
embodiment employs a plurality of mutually independent central
projections 84, and the continuously extending peripheral
projections as well. Therefore, the rubber stopper 41 is capable of
effectively absorbing a shock upon abutting contact of the rubber
stopper against the sub frame 49, in comparison with the rubber
stopper whose abutting portion is entirely constituted by the
peripheral projection 82. Further, the rubber stopper 41 of the
present invention is free from the problems of damages of central
projections 84 due to excess deformation thereof, and a resultant
lower durability thereof. Accordingly, the present rubber stopper
41 can exhibit both of excellent stopper characteristics and
sufficient durability, concurrently.
[0075] It should be appreciated that since the peripheral
projections 82 overlap the laterally opposite corners of the first
abutting plane of the connector arm 29 with a sufficient width and
thickness dimensions, it is effectively prevented a conventionally
experienced excess outward displacement or elastic deformation of
the peripheral portion of the bottom wall portion 74 of the rubber
stopper 41 along an superficial profile of the rigid abutting
member, when the bottom wall portion 74 comes into abutting contact
with the sub frame 49. Accordingly, the rubber stopper 41 is less
likely to suffer from or free from a stress-concentration at a
local area pressed onto the corners of the first abutting plane of
the connector arm 29, and a resultant cracking or other defects due
to the stress concentration. Therefore, the rubber stopper having
the pair of peripheral projections of aforesaid unique structure
can enhance durability thereof, and resultant durability of the
stopper structure.
[0076] The rubber stopper 41 constructed according to the present
embodiment was actually measured in terms of its stopper
characteristics, i,e., load-deformation characteristics. The
obtained measurement is demonstrated in a graph of FIG. 9D.
Likewise, comparative examples 1-3 of rubber stoppers as shown in
FIGS. 11A-11C, were measured in terms their stopper
characteristics, and the obtained measurements are demonstrated in
graphs of FIGS. 9A-9C, respectively. In the comparative example 1
as shown in FIG. 11A, an abutting portion functions as a bound
stopper, is constituted by only the elastic base portion 74A of
flat-plate shape with a 4 mm wall-thickness dimension. In the
comparative example 2 as shown in FIG. 11B, the abutting portion
functioning as the bound stopper measures more values, i.e., 8 mm
in thickness.
[0077] The comparative example 3 as shown in FIG. 11C, has a
plurality of projecting portions 100 formed on and projecting from
the elastic base portion 74A, and extending in the lateral
direction with a relatively small width dimension. FIGS. 12A and
12B show schematic illustrations of the rubber stopper 41 of the
present invention. FIGS. 12C and 12D show a comparative example 4
that is different from the present rubber stopper 41 in that no
central projection is formed. FIGS. 12E and 12F show a comparative
example 5 that is different from the present rubber stopper 41 in
that no peripheral projection is formed.
[0078] Stopper characteristics of the comparative examples 4 and 5
were similarly measured, and is demonstrated on graphs of FIGS. 10A
and 10B. As is understood from a load-deformation line illustrated
on the graph of FIG. 9D, the rubber stopper 41 exhibits soft spring
characteristics as a low deformation region, and experiences smooth
and abrupt raise of the line, once the rubber stopper 41 undergoes
somewhat deformation thereof. This shows that the rubber stopper 41
can exhibit both of soft-touch stopper characteristics and an
excellent displacement limiting performance. On the other hand, the
graphs of FIGS. 10A and 10B show that the comparative examples as
shown in FIGS. 12C-12F are insufficient one of these
characteristics.
[0079] The rubber stopper 41 constructed according to the present
embodiment, as well as a comparative examples 1-5 as discussed
above were actually installed on an automotive vehicle, and their
durability were actually judged by visual inspection after a
driving test, while stopper performance during driving were
actually evaluated by a feeling test for a shock. Obtained
measurements and results of the feeling tests are shown in Table 1.
As is understood from Table 1, the present invention is superior
than any other comparative examples in terms of stopper
characteristics and durability thereof
1 TABLE 1 COMP. COMP. COMP. COMP. COMP. EXAMPLE EXAMPLE EXAMPLE
PRESENT EXAMPLE EXAMPLE 1 2 3 INVENTION 4 5 Thickness 4.0 mm 8.0 mm
2.5 mm 5.0 mm 5.0 mm 3.5 mm [Base] [Projection] 2.5 mm [Peripheral
3.5 mm 3.5 mm None Projection] [Central 1.5 mm None 3.5 mm
Projection] Durability .largecircle. .largecircle. X .largecircle.
.largecircle. X Graph No. Feeling X X .largecircle. .largecircle.
.DELTA. X Test
[0080] Table 1 indicates an insufficient durability of the
comparative example 3 as shown in FIG. 11C, This insufficiency is
derived from the fact that a portion P indicated in FIG. 11D is
situated on the laterally opposite corners of the connector arm 27
may be locally and excessively deformed due to the presence of this
corner, and subjected to a relatively large stress, leading to
earlier cracks and deterioration of the rubber stoppers.
[0081] While the presently preferred embodiment of this invention
has been described above in detail by 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.
[0082] The stopper structure of the present invention may be
similarly applicable to a various types of engine mounts, other
than a fluid-filled hanging engine mount in the illustrated
embodiment.
[0083] It is also 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 spirit and scope of the invention defined in the
following claims.
* * * * *