U.S. patent application number 09/739803 was filed with the patent office on 2001-12-20 for fluid-sealed anti-vibration device.
Invention is credited to Saitoh, Jun.
Application Number | 20010052664 09/739803 |
Document ID | / |
Family ID | 26581973 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010052664 |
Kind Code |
A1 |
Saitoh, Jun |
December 20, 2001 |
Fluid-sealed anti-vibration device
Abstract
A first connecting member is connected to a second connecting
member by an elastic body member. A fluid chamber which is formed
inside the first connecting member, the second connecting member
and the elastic body member is divided into a main fluid chamber 17
and a sub-fluid chamber 18 by a partition member 15. An idle
orifice 20 and a damping orifice 21 communicate with both chambers.
In a part of a side wall member 9 which forms the main fluid
chamber 17 is formed a round hole 10 which is covered by a part of
the elastic body member to form a horizontally movable membrane 11.
A circular wall 44 is integrally formed with the partition member
15 to face the horizontal movable membrane 11 at predetermined
intervals. Resonance of the horizontal membrane 11 generated as a
result of fluctuations of internal pressure in the main fluid
chamber is controlled by the circular wall 44.
Inventors: |
Saitoh, Jun; (Saitama,
JP) |
Correspondence
Address: |
BIRCH, STEWART, KOLASCH & BIRCH, LLP
P.O. Box 747
Falls Church
VA
22040-0747
US
|
Family ID: |
26581973 |
Appl. No.: |
09/739803 |
Filed: |
December 20, 2000 |
Current U.S.
Class: |
267/140.13 |
Current CPC
Class: |
F16F 13/106
20130101 |
Class at
Publication: |
267/140.13 |
International
Class: |
F16F 005/00; F16M
005/00; F16F 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 1999 |
JP |
H11-368073 |
Aug 31, 2000 |
JP |
2000-263529 |
Claims
What is claimed is:
1. A fluid-sealed anti-vibration device comprising: a first
connecting member secured to a source of vibration; a second
connecting member secured to a car body; an substantially
cone-shaped elastic body member positioned therebetween; a fluid
chamber which is formed by the first connecting member, the second
connecting member, and the elastic body member, and of which the
wall is a part of the elastic body member; the fluid chamber being
divided by a partition wall into a main fluid chamber and a
sub-fluid chamber; and an orifice formed in the partition wall to
communicate with the main fluid chamber and the sub-fluid chamber;
characterized in that an elastic, horizontally movable membrane is
provided in a side wall member which encloses the main fluid
chamber in a substantially cylindrical manner, and a control wall
is provided in the main fluid chamber to face the horizontal
movable membrane at intervals.
2. The fluid-sealed anti-vibration device according to claim 1,
wherein the horizontal movable membrane is integrally formed with
the elastic body member.
3. The fluid-sealed anti-vibration device according to claim 1,
wherein the control wall is formed integrally with or separately
from a partition member.
4. The fluid-sealed anti-vibration device according to claim 1,
wherein a plurality of horizontal movable membrane is provided and
an eigen value of each horizontal movable membrane is changed.
5. The fluid-sealed anti-vibration device according to claim 1,
wherein a circular wall is formed inside the side wall member to
face the side wall member at intervals, space provided between the
circular wall and the side wall member opens to the main fluid
chamber, and a part of the circular wall facing the horizontal
movable membrane is the control wall.
6. A fluid-sealed anti-vibration device according to claim 1,
wherein an elastic membrane is provided on the partition member,
adapted to be elastically deformed as a result fluctuation of
internal pressure in the main fluid chamber and formed as a
non-circular member with a long side section and a short side
section and provided in the central part thereof with a curved
groove running substantially parallel to the long side section.
7. The fluid-sealed anti-vibration device according to claim 6,
wherein the elastic membrane is integrally provided with a stopper
projection on the reverse side of and substantially parallel to the
curved groove, and the stopper projection is formed only on the
long side section of the elastic membrane.
8. The fluid-sealed anti-vibration device according to claim 6,
wherein a periphery of the elastic membrane is integrally formed
with a continuous circular peripheral wall that is retained by the
partition member, and a clearance is provided at the retaining
section by the partition member to permit deformation of the
peripheral wall.
9. The fluid-sealed anti-vibration device according to claim 6,
wherein the partition member is provided with first to third
orifice passages, of which the first orifice passage is the damping
orifice passage for always communicating with the main fluid
chamber and the sub-fluid chamber, the second orifice passage can
be freely opened and closed, and the third orifice passage, of
which part is covered by the elastic membrane which is elastically
deformable to shut off the communication with the main fluid
chamber and the sub-fluid chamber, and the elastic membrane is
formed as the non-circular member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fluid-sealed
anti-vibration device suitable for use in an engine mount for an
automobile and the like.
[0003] 2. Description of the Prior Art
[0004] A fluid-sealed anti-vibration device is known in the prior
art wherein an elastic horizontal movable membrane is provided in a
part of a side wall member which encloses a main fluid chamber to
absorb the change of internal pressure in the main fluid chamber
(one example, Japanese Unexamined Patent Publication No. Hei
10-281214).
[0005] Moreover, a fluid-sealed anti-vibration device is known in
the prior art wherein an elastic membrane is formed as a circular
member and the fluctuation of fluid pressure in a main fluid
chamber can be absorbed by elastic deformation of the elastic
membrane. The elastic membrane is integrally provided with a
stopper projection serving as a circular wall. The stopper
projection is formed on the surface of the elastic membrane on a
sub-fluid chamber side. In the case of elastic deformation above a
predetermined level, in particular, a spring constant is
nonlinearly changed by allowing the stopper projection to abut a
partition member and the like.
[0006] In the case where such a horizontal movable membrane is
provided, the dynamic spring constant can be generally lowered, but
as shown by a dashed line in FIG. 6, a peak of the dynamic spring
constant is in a medium frequency range. It is considered that this
peak is generated as a reaction to the resonance of the horizontal
movable membrane (the peak which is a maximum value of such a
dynamic spring constant is hereinafter referred to as "dynamic
spring peak", while the minimum value is referred to as "dynamic
spring bottom").
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to control the
resonance of a horizontal movable membrane so that generation of
the dynamic spring peak can be controlled. In the present
invention, a frequency below 500 Hz is defined as low frequency, a
frequency between 100 and 500 Hz is defined as medium frequency,
and a frequency above 500 Hz is defined as high frequency. In each
graph in FIG. 6 and the like, the abscissa is the frequency, and
the ordinate is the dynamic spring constant (absolute value of
complex spring constant).
[0008] When an elastic membrane is provided in a partition member,
there is a case where a circular elastic membrane can not be
disposed due to layout conditions and must be changed to a
non-circular member with a long side section and a short side
section such as an oval shaped member. However, if the conventional
circular elastic membrane is simply changed to a non-circular
member such as that with an oval shape and the like, there is some
possibility that the elastic membrane must be retained by the
elastic membrane along the long side section for a long period of
time, and since the stopper projection continues circularly, the
elastic membrane can not be easily bent in response to the
fluctuation of fluid pressure of a main fluid chamber. As a result,
it is difficult to absorb the increase in the internal pressure. It
is therefore an object of the present invention to provide an
improved elastic membrane which can be easily bent in response to
the fluctuation from increase in the internal pressure and absorb
the increase in internal pressure even though the non-circular
elastic membrane is used, in which when the elastic deformation
exceeds a predetermined level, a spring constant can be changed
non-linearly in the same manner as the prior art.
[0009] The primary object of the present invention is to overcome
the abovementioned problems and to provide a fluid-sealed
anti-vibration device comprising a first connecting member secured
to a source of vibration, a second connecting member secured to a
car body, a substantially cone-shaped elastic body member
positioned therebetween, a fluid chamber which is formed by the
first connecting member, the second connecting member and the
elastic body member, and of which the wall is a part of the elastic
body member, the fluid chamber being divided by a partition wall
into a main fluid chamber and a sub-fluid chamber, and an orifice
provided in the partition wall to communicate with the main fluid
chamber and the sub-fluid chamber, characterized in that an elastic
horizontally movable membrane is formed in a side wall member which
encloses the main fluid chamber in a substantially cylindrical
manner, and a control wall is provided in the main fluid chamber to
face the horizontally movable membrane at intervals.
[0010] According to a second object of the present invention, the
horizontally movable membrane is integrally formed with the elastic
body member. At this time, the control wall can be provided
integrally with or separately from the partition member. Also, a
plurality of horizontally movable membrane can be provided to allow
the eigen value of each horizontally movable membrane to be
changed.
[0011] According to a third object of the present invention, a
circular wall is formed inside the side wall member to face the
side wall member at intervals, space provided between the circular
wall and the side wall member opens to the main fluid chamber, and
a part of the circular wall facing the horizontally movable
membrane is the control wall.
[0012] According to a fourth object of the present invention, an
elastic membrane is provided on the partition member and adapted to
be elastically deformed as a result of the fluctuation of internal
pressure in the main fluid chamber, the elastic membrane is formed
as a non-circular member with a long side section and a short side
section and provided in the central part thereof with a curved
groove running substantially parallel to the long side section.
[0013] At this time, on a surface of the elastic membrane opposite
to the curved groove, a stopper projection is integrally provided
substantially parallel to the curved groove. The stopper projection
can be formed only on the long side section. The periphery of the
elastic membrane is integrally formed with a continuous, circular
peripheral wall that is retained by the partition member, and a
clearance can also be provided at the retaining section by the
partition member so as to permit deformation of the peripheral
wall.
[0014] Further, the partition member is provided with first to
third passages of which the first passage is the damping passage
for always communicating with the main fluid and sub-fluid
chambers, the second passage can be freely opened and closed, and
the third passage, of which part is covered by the elastic membrane
which is elastically deformable to shut off the communication with
the main fluid and sub-fluid chambers, and the elastic membrane is
formed as the non-circular member.
[0015] According to the first invention, because a control wall is
provided to face a horizontally movable membrane, pressure on the
horizontally movable membrane generated as a result of vibration of
an elastic body member is controlled by the control wall and the
dynamic spring constant is lowered by membrane resonance. As a
result, generation of a dynamic spring peak generated in medium
frequency range can be controlled.
[0016] As shown in FIGS. 5 and 6, formation of the dynamic spring
peak can be freely controlled by changing the size of the control
wall. Also, as shown in FIGS. 7 and 8, the dynamic spring peak can
be controlled by changing the clearance between the horizontally
movable membrane and the control wall. Accordingly, the
fluid-sealed anti-vibration device can be regulated by changing the
setting of the control wall.
[0017] According to the second invention, a plurality of
horizontally movable membranes is provided, wherein if the eigen
value of each membrane is changed, the resonance of each
horizontally movable membrane is generated in different eigen
values and coupled resonance which is wide as a whole is generated.
As a result, a low dynamic spring effect can be realized in a wider
range. In the present invention, the eigen value is defined as
individual resonance frequency, which varies with the size,
thickness, materials (spring constant) and the like of the
horizontally movable membrane.
[0018] According to the third invention, since a circular wall is
formed to face the side wall member, it is easy to position the
control wall and the horizontally movable membrane.
[0019] According to the fourth invention, when the internal
pressure of the main fluid chamber increases, the elastic membrane
is sheared to bend and deform at the curved groove which is located
in the center thereof and runs substantially parallel to the long
side section, and which serves as a flexural center. In this
manner, even though the elastic membrane is formed as the
non-circular member with the long and short side sections, it can
easily bend in response to the increase in the internal pressure in
the main fluid chamber. As a result, it is possible to absorb the
increase in internal pressure of the main fluid chamber by
utilizing the low dynamic spring effect.
[0020] If the stopper projection is projectingly formed on a
surface opposite to the curved groove of the non-circular member,
when large vibrations are input to the main fluid chamber, the
stopper projection abuts the side of the partition member, whereby
the spring constant of the elastic membrane changes nonlinearly
and, as a result, the large input can be absorbed. Further, by
providing the stopper projection only on the long side section to
provide a discontinuous shape, the elastic membrane can be easily
bent.
[0021] Since the clearance is provided at the section where the
partition member retains the peripheral wall of the elastic
membrane, it is possible to realize easier deformation of the
elastic membrane. Further, the partition member is provided with
first to third passages, of which the first orifice passage is the
damping orifice passage for always communicating with the main
fluid and sub-fluid chambers, the second passage can be freely
opened and closed, and the third passage, of which part is covered
by the elastic membrane to shut off the communication with the main
fluid and sub-fluid chambers. Thus, by forming the elastic membrane
as the non-circular member, it is possible to provide an efficient
layout even in such a limited space as that of the partition member
where the circular member can not be positioned.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other objects, and advantages of the present
invention will become more apparent from the following description
when taken in conjunction with the accompanying drawings.
[0023] FIG. 1 is an entire cross-sectional view of a device
according to a first embodiment (corresponding to a view taken
along line 1-1 of FIG. 2);
[0024] FIG. 2 is a plan view of the external appearance of the
device;
[0025] FIG. 3 is an enlarged cross-sectional view of basic parts of
the device;
[0026] FIG. 4 is a plan view of a partition member section of the
device;
[0027] FIG. 5 is a partial cross-sectional view showing the change
in height of a control wall of the device;
[0028] FIG. 6 is a graph showing the change in dynamic spring
constant caused by the control wall;
[0029] FIG. 7 is a partial cross-section view showing the change in
clearance of the control wall;
[0030] FIG. 8 is a graph showing the change in dynamic spring
effect caused by the clearance change;
[0031] FIG. 9 is a development elevation depicting two movable
membranes shown side by side according to a fourth embodiment;
and
[0032] FIG. 10 is a graph showing the effect of the fourth
embodiment.
[0033] FIG. 11 is an entire cross-sectional view of an engine mount
according to an embodiment;
[0034] FIG. 12 is an enlarged view of Section A of FIG. 11;
[0035] FIG. 13 is a plan view of an elastic membrane according to
the embodiment viewed from a side of a main fluid chamber;
[0036] FIG. 14 is a cross-sectional view of the elastic membrane
taken along line 14-14 of FIG. 13;
[0037] FIG. 15 is a cross-sectional view of the elastic membrane
taken along line 15-15 of FIG. 13;
[0038] FIG. 16 is a bottom view of the elastic membrane;
[0039] FIG. 17 is a graph showing dynamic spring characteristics in
the case of a low amplitude; and
[0040] FIG. 18 is a graph showing damping characteristics in the
case of large amplitude.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Preferred embodiments of the present invention which are
provided as an engine mount for an automobile will now be described
with reference to the accompanying drawings.
[0042] Referring first to FIGS. 1 to 4, an engine mount as a
fluid-sealed anti-vibration device has a first connecting member 1,
a second connecting member 2 and an elastic body member 3. The
first connecting member 1 is secured to an engine (not shown) by a
screw member 4 and the second connecting member 2 is secured to the
automobile body (not shown) by a flange 5.
[0043] The elastic body member 3 is a substantially cone-shaped
member constructed of a suitable elastic material such as a known
rubber, of which the top section is integrally penetrated by the
first connecting member 1. A lower circumference of the elastic
body member 3 is provided with a flange 6 which is integrally
connected to a flange metal fitting 7 formed as a part of the
second connecting member 2. A lower section of the elastic body
member 3 extends further downward from the flange 6 to form an
inner lining section 8 which extends cylindrically and is
integrally secured to an inner surface of a side wall member 9.
[0044] The side wall member 9 forms a part of the second connecting
member 2, the outside of which is integrally connected to the
flange metal fitting 7 by welding. The circumference of the side
wall member 9 is provided with round holes 10 at intervals of
180.degree. in the circumferential direction. The inner lining
section 8 is not supported by the side wall member 9 at the round
hole 10 section and forms a horizontally movable membrane 11 which
can undergo free elastic deformation. Round grooves 12 are formed
at the circumferential locations of the horizontally movable
membrane 11 corresponding to the inside of the round holes 10 so
that the horizontally movable membrane 11 can be easily deformed.
The lower section of the side wall member 9 is integrally secured
to a flange 14 of a cylindrical base section 13 of the second
connecting member 2 by caulking. The circumference of a partition
member 15 and the circumference of a diaphragm 16 are secured to a
junction of the side wall member 9 and the cylindrical base section
13.
[0045] The partition member 15 forms a main fluid chamber 17
together with the elastic body member 3 and forms a sub-fluid
chamber 18 together with the diaphragm 16. The main fluid chamber
17 and the sub-fluid chamber 18 communicate through an idle orifice
20 for absorbing idling vibration formed in the partition member
15, and a damping orifice 21 for absorbing low frequency vibration.
The idle orifice 20 is an opening and closing type of orifice which
opens only at the time of idling, while the damping orifice 21 is
always open.
[0046] As is obvious from FIGS. 3 and 4, an outlet 22 of the idle
orifice 20 is closed when the top of a hollow valve 24 presses the
central section 23 of the diaphragm 16 toward the outlet 22. On the
other hand, the outlet 22 is opened when the inside of the valve 24
is forced from a communication passage 26 by a source of negative
pressure (not shown) to provide a negative pressure and the valve
24 is lowered against a return spring 25 disposed therein, thereby
allowing communication with the main fluid chamber 17 and the
sub-fluid chamber 18.
[0047] The valve 24 is formed by covering the surface of a
cup-shaped core bar member 27 with an elastic body 28. The lower
periphery of the elastic body 28 closely adheres to a lid-shaped
member 29 which engages a bottom section of the first connecting
member 1, so that the inside is maintained in an air-tight
condition. A supporting cylindrical metal fitting 30 engages the
inside of the cylindrical base section 13. The upper end of the
supporting cylindrical metal fitting 30 forms an inner flange 31
whereby the periphery of the diaphragm 16 is positioned between the
flange 31 and the partition member 15. The middle section of the
metal fitting 30 is provided with a step 32 projecting inward. The
lower end of the metal fitting 30 is bent inward to form a caulking
section 33 which overlaps the periphery of the lid-shaped member
29. A thickened end section 34 formed on the periphery of the
elastic body 28 is positioned between the step 32 and the caulking
section 33 whereby the end section 34 is caused to closely adhere
to the lid-shaped member 29.
[0048] Reference numeral 35 in FIG. 1 is a medium and high
frequency device, formed in a cup-shape which opens downward. The
device 35 is secured to the lower end of the first connecting
member 1 which projects into the main fluid chamber 17. The device
35 is adapted to move vertically together with the first connecting
member 1 so as to generate fluid column resonance in the medium and
high frequency range within the clearance formed between the medium
and high frequency device 35 and the elastic body member 3.
[0049] Reference numeral 36 is a stopper formed at the end of a
stopper arm 37 which extends in the radial direction from the first
connecting member 1. The stopper 36 enters a stopper bracket 38
formed in an arch shape upward from the flange metal fitting 7 and
contacts the flange 6 at the time of large vibration to control
deformation of more than a fixed level.
[0050] Construction of the partition member 15 will now be
described. As shown in FIGS. 3 and 4, the partition member 15 is
arranged to overlap three members, an upper member 40, an
intermediate member 41, and an lower member 42 vertically, with the
intermediate member 41 situated between the upper and lower
members. The upper member 40 is constructed of a comparatively
rigid plastic material. A flange 43 is formed on the circumference
thereof and a circular wall 44 is formed inside the flange 43
projecting upward. Both the flange 43 and the circular wall 44 are
integrally formed with the upper member 40. The circular wall 44
faces the side wall member 9 with a predetermined clearance
therebetween and in particular, a part of the circular wall 44
facing the horizontally movable membrane 11 forms a control wall
44a of the present invention.
[0051] The circular wall 44 is provided with a recess 45 in the
inside thereof, of which the lower surface is formed with an idle
orifice groove 46 in a vortex manner. One end of the idle orifice
groove 46 forms an inlet 47 which opens into the recess 45, while
the other end is guided to the center direction of the recess 45
and opens downward to communicate with the outlet 22 which is
formed substantially in the center of the lower member 42. The idle
orifice groove 46 overlaps the intermediate member 41 located
thereunder which closes the open section thereof, thereby forming
the idle orifice 20.
[0052] The intermediate member 41 is constructed of a comparatively
soft elastic material such as rubber and has a groove 50 which
opens upward at a position outside the idle orifice 20. The open
end of the groove 50 is closed by the flange 43 to form a part of
the damping orifice 21. The groove 50 communicates with the main
fluid chamber 17 through an inlet 51 which is formed in one end of
the flange 43 and communicates with the damping orifice 21 on the
side of the lower member 42 at a communicating opening 52 which is
formed in other end of the flange 43.
[0053] A border section between an outer peripheral side of an
inner periphery section 48 and the groove 50 is provided with a
slope 49. The intermediate member 41 is also provided with a slope
41a at a border section between the idle orifice groove 50 and the
flange 43. The faces of the two slopes 49 and 41a are arranged to
slide with respect to one another.
[0054] The lower member 42 is also constructed of comparatively
rigid material such as resin in the same manner as the upper member
40. A groove 53 which opens upward is formed in the outer periphery
of the lower member 42 and is closed by the bottom section of the
intermediate member 41 to form a part of the damping orifice 21.
The positions of the two grooves 53, 50 partially overlap, wherein
one end of the groove 53 communicates with the communicating
opening 52, while the other end forms an outlet 55 which opens into
the sub-fluid chamber 18.
[0055] An operation of the present embodiment will now be
described. As shown in FIG. 6, a device with the circular wall 44
is compared with a device without the wall 44 (see a dashed line).
In the device with the circular wall 44, the dynamic spring peak
can be remarkably controlled compared with the device without the
wall 44. The dynamic spring peak P3 in the case where the circular
wall 44 is not provided is much higher than the peaks P1, P2 in the
case where different sizes of circular walls 44 are provided.
[0056] When the circular wall 44 is not provided, the total energy
of the fluctuations in internal pressure due to the deformation of
the elastic body member 3 is added to the horizontally movable
membrane 11 and as a result, the resonance energy of the
horizontally movable membrane 11 becomes large. Thus, the low
dynamic spring effect generates a remarkable dynamic spring bottom
B3 and as a reaction to this dynamic spring bottom B3, the dynamic
spring peak P3 with a high dynamic spring constant is generated. On
the other hand, by providing the circular wall 44, the dynamic
spring bottoms B1, B2 in the case where the membrane resonance
energy is limited rise higher and as a reaction to this, the
dynamic spring peaks P1, P2 become low. Thus, the vertical
variation width of the dynamic spring constant becomes small
inversely and as a result, equalized low dynamic spring
characteristics with a smooth curved line as a whole can be
realized.
[0057] As a control means for the amount of energy to generate such
a membrane resonance, it is possible to change the size of the
circular wall 44 covering the horizontally movable membrane 11 and
to change the distance between the circular wall 44 and the
horizontally movable membrane 11. As shown in FIG. 5, the height of
the circular wall 44 (i.e. the height which correlates with the
size for covering he horizontally movable membrane 11) can be
optionally set, for example, to the same height as the horizontally
movable membrane 11, i.e. a height of 100% covered (see the solid
line) and to a height slightly lower than that of the horizontally
movable membrane 11, i.e. a height of 75% covered (see the broken
lie).
[0058] The change of the dynamic spring constant according to this
setting is shown in FIG. 6. When the height of the circular wall 44
is set to 100%, the dynamic spring peak is P1 and the dynamic
spring bottom is B1. When the height of the circular wall 44 is set
to 75%, the dynamic spring peak is B2 and the dynamic spring bottom
is B2. The relationship for the dynamic spring bottom is B1>B2
and for the dynamic spring peak is P1<P2. Accordingly, it is to
be noted that the higher the circular wall 44 (namely, the larger
the covered percentage), the smaller the gap between the dynamic
spring peak and the dynamic spring bottom.
[0059] This means that when the internal pressure exerted on the
horizontally movable membrane 11 as a result of deformation of the
elastic body member 3 is controlled, the energy related to the
resonance of the horizontally movable membrane 11 is reduced, and
thus the more the horizontally movable membrane 11 is covered, the
more the height of the dynamic spring peak is controlled and the
energy of the membrane resonance is reduced. By reducing and
equalizing the vertical variation width of the dynamic spring
constant, it is possible to realize low dynamic spring
characteristics with a smooth curved line as a whole. Accordingly,
by changing the height of the circular wall 44, it is possible to
optionally adjust the dynamic spring peak.
[0060] On the other hand, as shown in FIG. 7, adjustment can be
made by changing the distance, i.e. the clearance between the
circular wall 44 and the horizontally movable membrane 11, with the
height of the circular wall 44 fixed. Namely, when the clearance is
changed to Large (solid line), Medium (dashed and dotted line), and
Small (dashed line), the dynamic spring constant changes, as shown
in FIG. 8, to P4<P5<P6 and B4>B5>B6 in sequence when
each dynamic spring peak is P4, P5 and P6 from the clearance Small,
and the dynamic spring bottom is B4, B5, and B6 in the same manner
as above. Accordingly, it is to be understood that the depression
effect of the dynamic spring peak and the equalization effect of
the dynamic spring constant change in order of clearance, i.e.
Large<Medium<Small.
[0061] This means that the smaller the clearance, the more the
amount of energy related to deformation of the horizontally movable
membrane 11 out of the energy of the fluctuation in the internal
pressure as a result of the elastic deformation of the elastic body
member 3 is limited. Accordingly, it is clear that the dynamic
spring peak can also be regulated by adjusting the clearance. If
the clearance is combined with each change of height, it is further
possible to make more accurate adjustment in wider frequency
ranges.
[0062] FIG. 9 relates to a fourth embodiment and is a development
elevation depicting two horizontally movable membranes 11 facing at
intervals of 180.degree., shown side by side. In this embodiment,
when the diameter of one of the horizontally movable membranes 11A
is D1 and the diameter of the other 11B is D2, the relationship
between the two horizontally movable membranes is changed to:
D1<D2.
[0063] With this arrangement, because there is a difference in the
eigen values of the horizontally movable membranes 11A and 11B, it
is possible to generate membrane resonance in a different frequency
and, as a result, a coupled resonance is generated. FIG. 10 is a
graph showing the coupled resonance, in which a combination of two
different kinds of horizontally movable membranes (large size and
small size) indicated by a dashed line clearly shows a smaller
dynamic spring peak P7 (highest one is shown) than a single use of
the horizontally movable membrane (i.e. same as the first
embodiment) shown by a solid line.
[0064] A case where four horizontally movable membranes are
provided at intervals of 90.degree. and their sizes are changed to
two, each, large and small, is shown by a long and short dashed
line. The dynamic spring peak P8 (highest one is shown) of the
coupled resonance is much lower and formed on the high frequency
side.
[0065] Thus, if the horizontally movable membranes are combined by
changing the eigen value, it is possible to realize a lower dynamic
spring effect as a result of the coupled resonance and also to
realize a low dynamic spring effect in the wider frequency ranges.
Further, adjustment with a high degree of freedom is possible.
[0066] It is to be noted that the present invention is not limited
to the embodiments described above, but may be varied in many ways.
For example, the circular wall 44 is not provided, but an
independent control wall 44a may be provided only at a section
where it corresponds to the horizontally movable membrane 11. In
this manner, it is also possible to fully control the resonance of
the horizontally movable membrane 11. The control wall 44a or the
circular wall 44 may be provided separately from the partition
member 15.
[0067] A third embodiment of the present invention which is
provided with an elastic membrane in the partition member. FIG. 11
is an entire cross-sectional view of the engine mount and FIG. 12
is an enlarged view of Section A of FIG. 11. First, in FIG. 11,
reference numeral 101 is a first connecting member which is secured
to an engine side by a bolt element 102 and reference numeral 103
is a second connecting member secured to a body side by a bolt 104.
105 is an elastic body member constructed of a suitable elastic
material such as rubber, which has a substantially cone-shaped dome
element 106 and a cylindrical element 107 following the dome
element 106.
[0068] The cylindrical element 107 integrally adheres to an inner
peripheral side of a substantially cylindrical rigid body wall 108
of which the outer peripheral side integrally overlaps a
cylindrical element 103a formed as a part of the second connecting
member 103. A part of the cylindrical element 103a and the rigid
body wall 108 is formed with a circular hole 109 which is covered
by a part of the cylindrical element 107. The part of the
cylindrical element 107 serves as a movable membrane 110 which is
elastically deformable.
[0069] The movable membrane 110 is covered by a holder 111 with a
substantially funnel-shaped section from the outside of the
cylindrical element 103a. A pipe element 112 projecting outward
from the central part of the holder 111 is connected to a switching
valve 114a. Switching an atmospheric release or connection to a
negative pressure source such as depression at engine manifold can
be performed by this switching valve 14a.
[0070] The inside of the holder 111 forms a control chamber 113
which is changed to an atmospheric release condition or to a
negative pressure condition by operation of the switching valve
114a. A movable membrane stopper 115 composed of an elastic member
such as rubber is provided between the holder 111 and the movable
membrane 110 to control the elastic deformation of the movable
membrane 110 at a predetermined level.
[0071] An opening section of the cylindrical element 107 is covered
by a partition member 116. Formed between the partition member 116
and the elastic body member 105 is a main fluid chamber 120 of
which the wall is part of the elastic body member 105. A sub-fluid
chamber 122 is formed on the side of the partition member 116
opposite to the main fluid chamber 120 and is covered by a
diaphragm 121. An incompressible fluid is filled into and sealed in
the main fluid chamber 120 and the sub-fluid chamber 122. The
partition member 116 is formed by overlapping three members, an
upper partition 117, an intermediate partition 118, and a lower
partition 119 of which each member is composed of a suitable rigid
material such as synthetic resin.
[0072] In the upper partition 117, as similarly as above mentioned
embodiments, a circular wall 140 is integrally formed projecting
upward. The circular wall 140 faces the side wall member 108 with a
predetermined clearance therebetween and in particular, a part of
the circular wall 140 facing the horizontally movable membrane 110
forms a control wall 141. Between the control wall 141 and the
horizontally movable membrane 110, a gap with a predetermined size
is formed. Whereby the dynamic spring peak effect as similar as
each above mentioned embodiment can be attained.
[0073] Formed between the upper partition 117 and the intermediate
partition 118, and between the intermediate partition 118 and the
lower partition 119 is a helical damping orifice passage 123, of
which one end communicates with a common passage 124 formed between
the upper partition 117 and the intermediate partition 118 and the
other end communicates with the sub-fluid chamber 122 through an
opening section (not shown in the figure) formed at a part of the
lower partition 119.
[0074] The common passage 124 then communicates with an idle
orifice passage 125 which is a second passage formed in the upper
partition 117, and with an orifice hall 126 serving as a third
orifice passage in sequence. The orifice hall 126 opens to the main
fluid chamber 120. Therefore, the common passage 124 always
communicates with the main fluid chamber 120 and the sub-fluid
chamber 122 to generate a damping force relative to vibration with
a comparatively low frequency and large amplitude such as
suspension vibration, thereby absorbing the vibration.
[0075] The bottom section of the orifice hall 126 is covered by an
elastic membrane 127 composed of an elastic material such as rubber
whereby the communication of the orifice hall 126 with the
sub-fluid chamber 122 is shut off. With the vibration of this
elastic membrane 127, the fluid in the orifice hall 126 generates
fluid column resonance in a comparatively higher frequency range
such as when a vehicle starts.
[0076] An opening section (not shown) of the idle orifice passage
125 opens to the orifice hall 126 which communicates with the
damping orifice passage 123 through the common passage 124 as
described above. Although these opening areas are not shown in the
figure, the resonance frequency of each fluid column resonance is
tuned in order of the relation: the orifice hall 126>the idle
orifice passage 125>the damping orifice passage 123.
[0077] The outlet 128 of the idle orifice passage 125 on the side
of the sub-fluid chamber 122 is opened or closed by a thick section
121a which is formed at the central part of the diaphragm 121. When
the outlet 128 is opened, the idle orifice passage 125 communicates
with the main fluid chamber 120 and the sub-fluid chamber 122 to
fluid-resonate and absorb the vibrations during idling on a higher
frequency side than the damping orifice passage 123.
[0078] Opening and closing operations of the thick section 121a
mare performed by a separate opening and closing member 130. The
opening and closing member 130 is so arranged that the thick
section 121a is biased toward the periphery of the outlet 128 by a
return spring 131 and forms a closed actuating chamber 132 between
itself and a bottom member 133 to communicate with a pipe element
134 which is formed on the central part of the bottom member 133.
The pipe element 134 is connected to the switching valve 114b to
switch the atmospheric release condition or the negative pressure
condition. When the insides of the actuating chamber 132 and the
control chamber 113 are synchronized for switching, the switching
valves 114a and 114b can be made common.
[0079] When the inside of the actuating chamber 132 is kept under a
negative pressure, the opening and closing member 130 is lowered
downward in the figure against the return spring 131 to remove the
thick section 121a from the periphery of the outlet 128, whereby
the outlet 128 is opened so that the idle orifice passage 125
communicates with the main fluid chamber 125 and the sub-fluid
chamber 122.
[0080] By clamping a clamping flange 108a formed on the lower
section of the rigid body wall 108 in the figure and an upper
section of a lower cylindrical member 135, the partition member 116
is fixedly secured between the clamping flange 108a and a fixing
flange member 136 integrally attached to the inner peripheral side
of the lower cylindrical member 135. Further, each outer peripheral
section of the opening and closing member 130 and the bottom member
133 is overlapped and secured by clamping the upper and lower ends
of a ring member 137 which is integrally situated on the inner
periphery of the lower section of the lower cylindrical member 135
in the figure. Reference numeral 138 is an air hole formed on the
lower cylindrical member 35 so that it overlaps partially the ring
member 137.
[0081] Each of the second connecting member 103, the rigid body
wall 108, the lower cylindrical member 135, the fixing flange
member 136, and the ring member 137 is composed of a suitable
material with stiffness properties such as a metal. Reference
numeral 139 in the figure is a substantially plate-shaped
intermediate and high frequency device that is adapted to generate
fluid column resonance between itself and the dome element 106 in
intermediate and high frequency ranges.
[0082] As shown in FIG. 12, the elastic membrane 127 of which the
body section 150 crosses the intermediate section of the orifice
hall 126 is provided on the central section thereof with a curved
groove 151 on the main fluid chamber 120 side.
[0083] A pair of stopper projections 152, 152 is projectingly
provided on a surface of the sub-fluid chamber 122 opposite to the
curved groove 151 to position the central section of the elastic
membrane therebetween. The outside ends of the stopper projections
are provided with abutting slopes 153, 153, respectively. A curved
recess 154 is formed between the stopper projections 152, 152. The
periphery of the body section 150 is formed with a thin section 155
and a vertical wall-shaped peripheral wall 156 is provided at the
edge section outside the thin section 155 to enclose the body
section 150 circularly.
[0084] As shown in these FIGS. 13 to 16, the elastic membrane 127
is formed in an oval shape with a linear long side section 157 and
an arc-shaped short side section 158 and a curved groove 151 is
formed parallel to and within the range of the long side section
157. In the present invention, the short side section 158 is a
radius section connecting the end sections of the long side
sections 157, 157, while the short side is a section enclosed by a
straight line connecting the end sections of the long side sections
157, 157 and the short side section 158.
[0085] The stopper projection 152 is also paired to position the
curved groove 151 therebetween and is formed parallel to the curved
groove 151 and the long side section 57. Both ends of each stopper
projection 152 in the longitudinal direction are formed as free
ends, and no stopper projection is formed connecting these opposing
free ends in the short side section 158.
[0086] The thin section 155 and the peripheral wall 156 are
circularly formed in succession on the front and back of an elastic
membrane 127 and the peripheral wall 156 is formed to project long
on two sides. The projecting length of the peripheral wall 156 in
the present embodiment is longer than that of the stopper
projection 152.
[0087] As shown best in FIG. 12, the upper side of this peripheral
wall 156 engages a circular groove 161 formed on forked sections 60
of the upper partition 117. An inner peripheral section 162 of the
forked section 160 is provided with a step to narrow the passage
cross-section at the intermediate section of the orifice hall 126
and a surface facing the circular groove 161 is formed with a slope
163 and the end of the inner peripheral section 162 is close to the
thin section 155. The slope 163 serves to allow the peripheral wall
156 which originally stands upright as shown in a vertical line, to
bend outward. The end of the slope 163 provides a clearance 164
between itself and the peripheral wall 156 to permit elastic
deformation of the peripheral wall 156 when bent inwardly.
[0088] On the other hand, the lower side of the peripheral wall 156
in FIG. 12 engages the circular groove 166 formed on a forked
section 165 of the lower partition 119. The inner peripheral
section 167 of the forked section 165 is provided with a narrow
section in the area where a part of the end of the inner peripheral
section 167 is close to the thin section 155 of the elastic
membrane 127 so that a predetermined clearance is formed between
the inner peripheral section 167 and the stopper projection 152.
The intermediate section of the inner peripheral section 167 is
formed in a slant and a step 168 on a slant to face the abutting
slope 153 of the elastic membrane 127 and the lower section thereof
is provided with a widened section.
[0089] In this manner, when the elastic membrane 127 undergoes
elastic deformation, the right and left stoppers 152, 152 open
outward. When the elastic membrane 127 is deformed as shown in the
virtual line of the figure, the abutting slope 153 first abuts the
step 168 to deform the end section of the stopper projection 152.
When the end section is deformed further, the entire stopper
projection 152 is pushed to the narrow section on the top of the
inner peripheral section 167 and is deformed.
[0090] An operation of the present embodiment will now be
described. When a comparatively small vibration is input to the
main fluid chamber 120, the internal pressure increases in response
to the input of this vibration to push the body section 150 of the
elastic membrane 127 downward from the top side of FIG. 12. Since
the body section 150 is provided on the central section thereof
with the curved groove 151 parallel to the long side section 157,
in the cross-section of the short side section of FIGS. 12 and 14,
the body section 150 is sheared to bend using the curved groove 151
as a fulcrum.
[0091] Accordingly, although the long side section 157 is linearly
secured to the partition member 116 side over the long area, the
elastic membrane 127 easily undergoes elastic deformation in
response to the increase of internal pressure of the main fluid
chamber 120 to absorb the increase of the internal pressure,
wherein the low dynamic spring effect can be realized.
[0092] Further, each end of the stopper projections 152, 152 in the
longitudinal direction is provided as a free end, and the stopper
projection 152 is not formed on the side of the short side section
to provide a discontinuous shape. It is therefore easier to bend
the elastic membrane in the direction of the short side section
158.
[0093] Since the upper section of the peripheral wall 156 is pushed
to open outward by the slope 163 of the inner peripheral section
162, the initial spring constant of the elastic membrane 127
becomes large. By providing the clearance 164, when the body
section 150 is elastically deformed, the elastic deformation can be
further promoted by means of the elastic deformation of the
peripheral wall 156.
[0094] If larger vibrations are further input, the ends of the
stopper projections 152, 152 open in opposite directions. As a
result, the abutting slope 153 first abuts against the step section
168 of the inner peripheral section 167 to elastically deform the
end of the stopper projection 152, thereby increasing the spring
constant of the elastic membrane 127.
[0095] If the elastic membrane 127 undergoes further elastic
deformation, the stopper projections 152, 152 are pushed to the
narrow section of the inner peripheral section 167 for further
elastic deformation, thereby increasing the spring constant
further.
[0096] Accordingly, when large vibrations are input, the spring
constant is also non-linearly changed in proportion to the
magnitude of the vibration. By increasing the spring constant, the
quantity of flow flowing into the damping orifice passage 123 is
increased to generate fluid column resonance in the damping orifice
passage 123, wherein a larger damping force is generated and the
vibration is thus absorbed.
[0097] FIG. 17 is a graph showing the relation between the dynamic
spring constant and the frequency in the case of a small amplitude
and FIG. 18 is a graph showing damping characteristics in the case
of a large amplitude, wherein a solid line shows the present
embodiment, while a broken line shows a comparative example in
which the same oval shape as the present embodiment is utilized,
but the curved groove 151 is not provided and the stopper
projection is formed circularly. FIG. 17 shows that the present
embodiment can realize a remarkable low dynamic spring effect and
FIG. 18 shows that almost the same high damping as the prior art
can be realized.
[0098] As is obvious from these graphs, a low dynamic spring effect
in proportion to a small vibration input can be realized. Also, a
comparatively large damping force can be generated in proportion to
a large vibration input to realize more or less the same high
damping as the prior art. It is therefore possible to obtain an
ideal low dynamic spring effect and high damping
characteristics.
[0099] Further, even though the partition member 116 is
horizontally provided with three passages of the damping orifice
passage 123, the idle orifice passage 125, and the orifice hall
126, if the elastic membrane 127 provided in the orifice hall 126
is formed as an oval, non-circular member, it is possible to
arrange the elastic membrane 127 even in difficult layout
conditions in which a circular elastic membrane 127 can not be
provided.
* * * * *