Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2001-08-09
2003-01-28
Schwartz, Christopher P. (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
Reexamination Certificate
active
06511060
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an engine mount used for installing an engine on a vehicle body.
In general, when an automobile engine and the like is installed on a vehicle body, engine mounts are interposed therebetween in order to control vibration transmission from an engine to a vehicle body. One prior art example of an engine mount is shown in FIG.
5
. Said engine mount comprises a body side metal fitting
101
fixed to a vehicle body, an engine side metal fitting
102
fixed to an engine, a vibration isolating base body
103
formed of a rubber elastic body interposed between both of the metal fittings
101
and
102
, and a liquid chamber
104
. The engine side metal fitting
102
is provided with a stopper rubber portion
107
substantially in a disc shape protruding radially outwardly from said metal fitting constituted of an outer peripheral flange
105
protruding radially outwardly from said metal fitting and a coating rubber
106
covering the outer periphery of the outer peripheral flange
105
. The engine side metal fitting
102
is disposed substantially concentrically with and spaced from the body side metal fitting and the stopper rubber portion
107
is opposed to an inner periphery of the body side metal fitting
101
so as to absorb the impact force generated at the time when a load in a radial direction is applied and prevent the deterioration of riding comfort on a vehicle.
However, since the stopper rubber portion
107
is concentrically disposed at the inside of the body side metal fitting
101
, a radius of curvature of the outer periphery thereof is smaller than that of the inner periphery of the body side metal fitting
101
. As a result, at the time when a load in the radial direction is applied, the edge of the stopper rubber portion
107
is first brought into contact with a small area of the inner periphery of the body side metal fitting, and thereafter, the contact edge is distorted inwardly to extend gradually the contact area of the stopper rubber portion
107
with the body side metal fitting.
Consequently, the stopper rubber portion
107
is greatly distorted at the edge portion to be first brought into contact with the body side metal fitting
101
. Thus, when a radial load is repeatedly applied to the engine mount during vehicle running on a bad road for a long period, it is likely to cause cracks of the stopper rubber portion.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the present invention to improve the durability of the stopper rubber portion in an engine mount, and another object of the present invention is to enhance riding comfort by damping a vibration transmitted from the stopper rubber portion to a vehicle body.
In order to attain the above objects, the present invention intends to uniform the distortion of the stopper rubber portion to the utmost by contacting widely the stopper rubber portion with the body side metal fitting at the time when a radial load is applied to the engine mount comprising a cylindrical body side metal fitting secured to a vehicle body, an engine side metal fitting secured to an engine, a vibration isolating base body made of an elastic rubber body interposed between the two metal fittings and a stopper rubber portion substantially in a disc shape protruding radially outwardly from the engine side metal fitting and disposed substantially concentrically with and spaced from the body side metal fitting. “Radial” or “radially” means the direction perpendicular to the axial direction passing through a center of the body side metal fitting. The stopper rubber portion is widely contacted with the body side metal fitting as follows.
Assuming that two radial directions orthogonal to each other in a radial plane perpendicular to the axis of the body side metal fitting are one direction and another direction, respectively, contact parts that contact the inner periphery of the body side metal fitting when a load is applied in one direction are denoted as one-direction contact parts and contact parts that contact the inner periphery of the body side metal fitting when a load is applied in another direction are denoted as another-direction contact parts. In the present invention, a center of curvature of an outer periphery of each one-direction contact part positioned at one direction of two radial directions orthogonal to each other in a radial plane is displaced from a center of curvature of an inner periphery of the body side metal fitting in the one direction and a radius of curvature of the outer periphery is arranged to be larger than a radius of curvature of an imaginary circle passing through a single point of the outer periphery of the stopper rubber portion concentrically with the inner periphery of the body side metal fitting. In such a manner, as compared with such a case that the outer periphery of the stopper rubber portion is arranged to be a circle, i.e. the imaginary circle, concentric with the inner periphery of the body side metal fitting, the one-direction contact parts contact with the body side metal fitting over a wide region and local rubber distortion is diminished. When the radius of curvature of the one-direction contact parts is larger than the imaginary circle, the contact parts contact widely with the inner periphery of the body side metal fitting. However, when the radius of curvature of the one-direction contact parts is larger than the inner periphery of the body side metal fitting, each of the contact areas of the contact parts becomes small. Accordingly, the radius of curvature of the one-direction contact parts shall be arranged to be larger than the imaginary circle and equal to or smaller than the radius of curvature of the inner periphery of the body side metal fitting.
Namely, the present invention provides an engine mount comprising a cylindrical body side metal fitting secured to a vehicle body, an engine side metal fitting secured to an engine, a vibration isolating base body made of an elastic rubber body interposed between the two metal fittings and a stopper rubber portion formed substantially in a disc shape protruding radially outwardly from the engine side metal fitting and disposed substantially concentrically with and spaced from the body side metal fitting. The stopper rubber portion is arranged in such a manner that a center of curvature of an outer periphery positioned at one direction of two radial directions orthogonal to each other in a radial plane being displaced from a center of curvature of an inner periphery of the body side metal fitting to the one direction and a radius of curvature of the outer periphery being arranged to be larger than a radius of curvature of an imaginary circle passing through a single point of the outer periphery of the stopper rubber portion concentrically with the inner periphery of the body side metal fitting and equal to or smaller than a radius of curvature of the inner periphery of the body side metal fitting, so that contact parts contacting with the body side metal fitting in the one direction of two radial directions orthogonal to each other are brought into contact with the body side metal fitting over a wide region.
Especially when the radius of curvature of the one-direction contact parts is arranged to be substantially equal to that of the inner periphery of the body side metal fitting, the entire outer periphery of the one-direction contact parts is brought into contact with the body side metal fitting.
The stopper rubber portion comprises an outer peripheral flange protruding radially outwardly from the engine side metal fitting and a coating rubber covering an outer periphery of said outer peripheral flange. Accordingly, the above-mentioned arrangement of the radius of curvature of the one-direction contact parts corresponds to the arrangement for the outer periphery of the coating rubber.
From the above viewpoint, the configuration of the outer peripheral flange and the rubber thickness of the coating rubber are not required to be limited specifically. However,
Inada Tsuyoshi
Kato Hironori
Yamamoto Kentaro
Schwartz Christopher P.
Toyo Tire & Rubber Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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