Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2001-02-09
2002-05-21
Rodriguez, Pam (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
Reexamination Certificate
active
06390458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a fluid-filled elastic mount adapted to provide a vibration damping effect on the basis of flows of a fluid filling the fluid chamber thereof. More particularly, the present invention is concerned with such a fluid-filled elastic mount that is novel in construction and which is suitably used as an engine mount, a body mount or other mounts for an automotive vehicle.
2. Description of the Related Art
As one type of a vibration damping device such as a vibration damping coupling (bushing) or mount, which is interposed between two members of a vibration system for flexibly connecting these two members or mounting one of these members on the other member in a vibration damping manner, there is known a fluid-filled elastic mount wherein a first metallic mounting member and a second metallic mounting member having a hollow cylindrical configuration are spaced apart from each other such that the first mounting member is disposed on the side of one of opposite open ends of the second mounting member, and are elastically connected to each other by an elastic body, whereby the one open end of the second mounting member is fluid tightly closed by the elastic body. The other open end of the second mounting member is fluid tightly closed by a flexible rubber diaphragm, to thereby define a fluid chamber between the elastic body and the flexible diaphragm, which is filled with a non-compressible fluid. The fluid-filled elastic mount further includes a metallic partition member supported by the second mounting member, which is adapted to divide the fluid chamber such that a pressure-receiving chamber which is partially defined by the elastic body is formed on one side of the partition member, while a variable-volume equilibrium chamber which is partially defined by the flexible diaphragm formed on the other side of the partition member. These pressure receiving and equilibrium chambers communicate with each other by an orifice passage. Upon application of vibrational loads between the first and second mounting members, a pressure of the fluid in the pressure receiving chamber changes due to elastic deformation of the elastic body, generating a pressure difference of the fluid between the pressure receiving and equilibrium chambers. Based on this pressure difference of the fluid, the non-compressible fluid forcedly flows through the orifice passage between the pressure receiving and equilibrium chambers, so that the fluid-filled elastic mount can exhibits an excellent vibration damping effect, owing to resonance or flows of the fluid flowing through the orifice passage. In the light of this excellent vibration damping effect, the elastic mount of this type is favorably used as an engine mount or a body mount for an automotive vehicle, for example.
Such a fluid-filled elastic mount can exhibit a desired vibration damping effect based on the resonance or flows of the fluid flowing through the orifice passage, by suitably tuning or determining a length and a cross sectional area of the orifice passage. In order to exhibit the excellent vibration damping effect of the elastic mount, the orifice passage needs to be made longer enough to assure a sufficiently large amount or mass of the fluid flowing through the orifice passage. To this end, the orifice passage may be conventionally constructed by using the partition member and an annular closure member made of metal, which is bonded at its outer peripheral portion to the periphery of the flexible diaphragm upon vulcanization of a rubber material for forming the flexible diaphragm. The annular closure member and the partition member are superposed on each other and fixed by calking at their peripheral portions to the other open end portion of the second mounting member which is remote from the first mounting member, to thereby define therebetween an annular passage extending in the circumferential direction thereof. The annular passage includes a partition wall formed at a circumferential portion thereof so as to fluid-tightly divide the annular passage in the circumferential direction, and a first and a second communication hole located on the opposite sides of the partition wall, so that the annular passage is held in fluid communication through the first and second communication hole with the pressure receiving chamber and the equilibrium chamber, respectively, thereby providing the orifice passage. According to this conventional structure of the orifice passage, the orifice passage is effectively and easily formed at the radially outward portion of the fluid chamber, so as to extend in the circumferential direction of the second mounting member with a circumferential length which is slightly smaller than the circumference of the second mounting member.
However, the conventional orifice structure may possibly suffer from a problem of insufficient fluid tightness at the partition wall portion, resulting in undesirable fluid communication between both ends of the orifice passage located on the opposite sides of the partition wall. This drawback makes it impossible to obtain a desired length of the orifice passage, resulting in deterioration of the vibration damping effect of the elastic mount.
To cope with the conventionally experienced problem, the present assignee has proposed an improved orifice structure as disclosed in JP-A-8-128491, wherein a partition wall made of an elastic body is formed at a circumferential portion of the annular passage so as to protrude from the partition member toward the closure member with a radial length which is reduced in a direction toward the closure member. That is, the partition wall has an inclined outer circumferential surface. The closure member is also arranged to have an inclined inner circumferential surface corresponding to the inclined outer circumferential surface of the partition wall. The inclined inner circumferential surface of the closure member is superposed on and forcedly pressed against the inclined outer circumferential surface of the partition wall, owing to the calking force applied between the partition and closure members. The inclined inner circumferential surface of the closure member which defines outer circumferential surface of the orifice passage inevitably causes undesirable reduction in the cross sectional area of the orifice passage, possibly leading to difficulty in assuring a required insufficient vibration damping effect of the elastic mount. Thus, the conventional fluid-filled elastic mount as descried above, still has some room for improvement.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a fluid-filled elastic mount which is novel in construction and which permits an easy formation of an orifice passage that is partially defined by and between a partition member and a closure member which are superposed on each other and fixed by calking to a second mounting member. The orifice passage extends in the circumferential direction of the partition and closure members with a circumferential length slightly smaller than a circumference of these members and with a sufficiently large cross sectional area. The orifice passage also exhibits an excellent fluid-tightness at a partition wall portion, thereby preventing undesirable fluid-leakage or fluid-communication between both ends of the orifice passage located on the opposite sides of the partition wall.
The above object of the invention may be achieved according to the principle of the invention, which provide a fluid-filled elastic mount including (a) a first mounting member and a generally cylindrical second mounting member, which are spaced apart from each other in an axial direction of the second mounting member, (b) an elastic body elastically connecting the first and second mounting members so as to fluid-tightly close one of axially opposite open ends of the second mounting member, (c) a partition member made of metal and extending in a direction perpendicular to the axial direction, (d) a clos
Okanaka Takehiro
Tanahashi Hiroaki
Bartz C T
Rodriguez Pam
Rossi & Associates
Tokai Rubber Industries Ltd.
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