Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2000-03-13
2001-10-30
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S219000
Reexamination Certificate
active
06308941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
This invention relates to a liquid sealed cylindrical-type vibration preventing apparatus suitably used for an engine mount of a vehicle, for example.
2. Related Art
Conventionally, when an engine of a vehicle which generates a vibration is mounted onto a body frame, an engine mount which supports the engine for preventing or absorbing the vibration has been used. One of such liquid sealed cylindrical-type vibration preventing apparatus is disclosed in Japanese Patent Laid-open (Koukai) No. 1-176827 and is shown in
FIGS. 7 and 8
.
This liquid sealed cylindrical-type vibration preventing apparatus is comprised of a pipe-shaped main-shaft metal fitting
101
, a generally cylindrical rubber elastic (resilient) body
103
, a first diaphragm
104
and a second diaphragm
107
, an annular orifice forming member
105
, and an outer cylindrical metal fitting
106
.
In detail, the rubber elastic body
103
is attached outside the main-shaft metal fitting
101
and has a pair of opened recesses
135
and
136
on an outer surface thereof. The first and second diaphragms
104
and
107
are formed integral with the rubber elastic body
103
and is disposed in one recess
135
circumferentially. The orifice forming member
105
is mounted outside the rubber elastic body
103
and covers opened portions of each recess
135
or
136
so that a main liquid chamber
155
in which a liquid (L) is filled and sealed is formed in another recess
136
, and a first sub liquid chamber
156
a
and a second sub liquid chamber
156
b
are formed between the orifice forming member
105
and the first and second diaphragms
104
and
107
. The orifice forming member
105
is also formed, at an outer peripheral surface thereof, a first orifice passage
157
which communicates the main liquid chamber
155
with the first sub liquid chamber
156
a
and a second orifice passage
158
which communicates the main liquid chamber
155
with the second sub liquid chamber
156
b
. The outer metal fitting
106
is coaxially disposed outside the orifice forming member
105
.
This liquid sealed cylindrical-type vibration preventing apparatus is mounted onto the vehicle, by attaching the main-shaft metal fitting
101
to a mount portion of one of the vehicle body side and engine side by bolts etc., and by engaging the outer-cylinder metal fitting
101
under pressure to another mount portion. Upon the mounting, the vibration preventing apparatus is directed so that the main liquid chamber
155
, is located at an upward portion or a downward portion through which the main vibration of the engine is transmitted.
When the vibration orthogonal to the main-shaft metal fitting
101
is applied between the main-shaft metal fitting
101
and the outer cylinder metal fitting
106
in this condition, the volume of the main liquid chamber
155
varies due to the elastic deformation of the rubber elastic body
103
, so that the liquid (L) flows between the main liquid chamber
156
and the first and second sub liquid chambers
156
a
and
156
b
via the first and second orifice passages
157
and
158
. Upon the liquid-flowing, the vibration of the engine shake (about 10 Hz) can be effectively reduced by a liquid pillar resonance operation of the liquid (L) which flows in the first orifice passage
157
. Also, the idle vibration (about 25 Hz) can be effectively reduced by a liquid pillar resonance operation of the liquid (L) which flows in the second orifice passage
158
.
Thus, this vibration preventing apparatus can reduce the two kinds of vibration of different, relatively small frequencies and of which difference is relatively small, by the liquid pillar resonance operation by the liquid (L) which flows in the first and the second orifice passages
157
and
158
.
By the way, to obtain the aimed frequency for tuning by selecting the cross-section area and the passage length of the first and second orifice passages
157
and
158
, and the spring rigidity of the first and second diaphragms
104
and
107
, the rubber elastic body
103
and the orifice forming member
105
which can be adapted to such tuning specification should be prepared and assembled. Here, the resonance frequency can be set higher when the cross-section area of the first and second orifice passages
157
and
158
is selected larger, the passage-length of the first and second orifice passages
157
and
158
is selected shorter and the spring rigidity of the first and second diaphragms
104
and
107
is selected higher or larger. Accordingly, the frequency is adjusted by preparing the rubber elastic body
103
and the orifice forming member
105
having the construction adapted to the required tuning specification and assembling them.
However, the recent diversification of the required specification needs various kinds of the construction members. Preparing the construction members for each specification is disadvantageous in the manufacturing cost and the administration.
In addition, there is a case where the idle vibration of about 25 Hz and a low-speed confine noise of about 80 to 100 Hz should be reduced, instead of the engine shakes (10 Hz) and the idle vibration (20 Hz). It is noted that the low-speed confine noise is the vibration which has the relatively higher frequency different from that of the idle vibration. For this reason, the conventional liquid sealed cylindrical-type vibration preventing apparatus which has the above mentioned construction can be hardly turned to reduce the idle vibration and the low-speed confine noise.
SUMMARY OF THE INVENTION
The present invention is made in view of the above circumstances in the conventional art, and therefore has an object to provide the liquid sealed cylindrical-type vibration preventing apparatus which has the construction convenient to be tuned to the frequency which can reduce two kinds of vibrations having the different frequency area (for example, the idle shake and low-speed confine noise), and which can be tuned easily.
In a liquid sealed cylindrical-type vibration preventing apparatus of the present invention, an outer cylindrical metal fitting is disposed radially outward of an intermediate cylindrical metal fitting disposed radially outward of a central main shaft (inner cylindrical metal fitting), width and length of a first orifice passage and a second orifice passage formed on an orifice forming member, and spring rigidity of a first diaphragm and a second diaphragm is improved. In detail, the vibration preventing apparatus is comprised of 1) a main shaft metal fitting, 2) an intermediate cylinder metal fitting disposed outside the main shaft substantially coaxial therewith and having a pair of windows facing to each other in a diameter direction, 3) a rubber elastic or resilient body disposed between the main shaft metal fitting and the intermediate cylinder metal fitting to connect the main shaft metal fitting and the intermediate cylinder metal fitting to each other and having a pair of recesses opened to each of the windows, 4) a first diaphragm held on a periphery of one window of the intermediate cylinder metal fitting and being disposed in one recess of the rubber elastic body, 5) an orifice forming member mounted on an outer periphery of the rubber elastic body, the orifice forming member forming a main liquid chamber and a sub liquid chamber between the orifice forming member, and the other recess and the first diaphragm respectively, and forming on an outer peripheral surface a first orifice passage communicating with the main liquid chamber and the sub liquid chamber, and a second orifice passage extending from the main chamber, 6) an outer cylindrical metal fitting disposed outside the intermediate cylinder metal fitting substantially coaxial therewith, and having a communicate window communicated with an atmosphere, and 7) a second diaphragm held by the outer cylinder metal fitting at an periphery of the communicate window and facing to the second orifice passage.
According to the liquid sealed cylindrical-type vibrat
Burch Melody M.
Oberleitner Robert J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokai Rubber Industries Ltd.
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