Hydraulically damped mounting device

Abstract: A restrictive fluid passageway (24) is defined between an outer sleeve (14) and a bracket (20) to provide fluid communication between a working chamber (18) and a compensation chamber or two compensation chambers (34, 36). In one embodiment, two compensating chambers are arranged outside of the outer sleeve. In another embodiment, one compensation chamber is arranged within the outer sleeve, and the outer sleeve is constituted by axially separated three sections, i.e., first and second sleeve sections and a spacer section interposed between the first and second sleeve sections. A resilient deformable member and flexible wall member has a pair of axially spaced sealing lips projecting outward from an outer circumferential surface. The sealing lips are interposed between matched ends of the first and second sleeve sections and the spacer section and sealingly contact an inner circumferential surface of the bracket.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulically damped mounting device of the bushing type for effectively preventing or reducing the transfer of shock and vibration therethrough, the device including inner and outer sleeves connected together by an elastomeric member bounding a fluid chamber. 2. Description of the Prior Art A hydraulically damped mounting device of the above described kind is well known in the art and is used for mounting an engine, transmission, etc. on an automotive vehicle body as disclosed in U.K. Patent Application No. 8715705 (Serial No. 2,192,968). The device has an orifice or restrictive fluid passageway interconnecting two fluid filled chambers for shock dampening upon deformation of an elastomeric member. From US-A-4 690 389 a hydraulically damped mounting device according to the first part of claim 1 is known having concentric inner and outer sleeves and a resilient member connecting both the inner and outer sleeve. A working chamber is provided which is filled with a fluid. The working chamber is in fluid communication to a compensation chamber formed of bellows by means of a passageway which is formed into a fixing bracket receiving said damping arrangement. A large number of parts is necessary to provide this prior elastomeric damping device accompanied by problems of sealing the compensation chamber. In DE-A 35 29 199 a hydraulically damped mounting device is disclosed, said damping device has first and second frame parts connected by means of a pipe. In the centre at least one of the frame parts a tube is provided being connected to an elastomeric element having two axially spaced ends which connect the outer surface of that tube with the inner surface of said frame part in order to provide a chamber filled with the fluid. Also the second frame part comprises an elastomeric element confining a fluid chamber. Both chambers are connected to the inner of the pipe so that a fluid exchange between both chambers is provided. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a hydraulically damped mounting device of the bushing type which comprises concentric rigid inner and outer sleeves having a space therebetween, a resilient elastomeric member within the space connecting the inner and outer sleeves together and thereby subdividing the space into two pockets, a working chamber in one of the pockets enclosed between the resilient member and the outer sleeve, the working chamber containing a fluid, a flexible wall member integral with the resilient member, disposed in the other of the pockets, a compensation chamber within the other of the pockets enclosed between the flexible wall member and the outer sleeve, a generally tubular bracket fitted on the outer sleeve and a passageway defined between the bracket and the outer sleeve and communicating the working chamber and the compensation chamber to provide fluid communication therebetween. The outer sleeve is axially separated to include first and second sleeve sections and a spacer section interposed between the first and second sleeve sections. The spacer section is in the form of a split ring and has an opening for providing fluid communication between the working chamber and the passageway. The resilient member and the flexible wall member have a pair of axially spaced annular sealing lips projecting outward from an outer circumferential surface. The sealing lips are interposed between matched ends of the first and second sleeve sections and the spacer section and sealingly contacts an inner circumferential wall of the bracket. The sealing lips provide a seal between the outer circumferential surface of the resilient member and the resilient wall member and the inner circumferential surface of the bracket for thereby sealing the working chamber, the compensating chamber and the passageway. The above structure is effective for improving the durability and reducing the manufacturing and assembling expense. It is accordingly an object of the present invention to provide a hydraulically damped mounting device of the type having outside of an outer sleeve a fluid passageway for providing communication between a working chamber and a compensation chamber, which can improve the durability. It is a further object of the present invention to provide a hydraulically damped mounting device of the above described kind, which can reduce the manufacturing and assembling expense. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a hydraulically damped mounting device according to the present invention; and Figs. 2 and 3 are sectional views taken along the lines IV-IV and V-V of Fig. 1, respectively. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Figs. 1 and 2, a hydraulically damped mounting device according to an embodiment of the present invention is generally indicated by 10 and includes concentric rigid inner and outer sleeves 12 and 14' and a resilient elastomeric deformable member 16' disposed between the inner and outer sleeves 12 and 14' to interconnect the same. The resilient deformable member 16' is moulded from a resilient material as rubber and bonded to the outer circumferential surface of the inner sleeve 12 and the inner circumferential surface of the outer sleeve 14' by sulfurization. The resilient deformable member 16' bounds on one side thereof, i.e., on the lower side in the drawings, a working chamber 18 filled with hydraulic fluid and on the other side, i.e., on the upper side thereof in the drawings, an atmospheric chamber 19 communicating with the atmosphere. In other words, the resilient deformable member 16' is disposed in the space between the inner and outer sleeves 12 and 14' to subdivide the space into two pockets. The working chamber 18 is arranged in one of the pockets and enclosed between or bounded by the resilient deformable member 16' and the outer sleeve 14'. The atmospheric chamber 19 is arranged in the other of the pockets. The outer sleeve 14' is fitted in a generally tubular bracket 20 together with the inner sleeve 12 and resilient deformable member 16'. The bracket 20 is formed with a circumferential groove 22 in the inner circumferential surface thereof to define a restrictive fluid passageway 24 between the inner circumferential surface of the bracket 20 and the outer circumferential surface of the outer sleeve 14' by the groove 22 in the inner circumferential surface of the bracket 20. In use, the device 10 is installed on a vehicle body at the bracket 20 or the inner sleeve 12 to support a power unit or the like at the inner sleeve 12 or the bracket 20. When a vibration is applied to the device 10 to cause a change in volume of the working chamber 18, hydraulic fluid moves out of the working chamber 18 to the compensating chamber 34' through the passageway 24. The viscosity of the hydraulic fluid and the constriction effect of the passageway 24 cause a strong damping force to be exerted on the vibration between the inner and outer sleeves 12 and 14'. By this, the device 10 can effectively absorb vibrations of low frequencies. The outer sleeve 14' consists of three axially separate sections, i.e., first and second sleeve sections 14'a and 14'b and a spacer section 14'c interposed between the sleeve sections 14'a and 14'b. A single compensation chamber 34' is bounded by one side of a flexible wall member 30' integral with the resilient deformable member 16' and the outer sleeve 14'. The other side of the flexible wall 30' member is in contact with the atmospheric chamber 19 in communication with the atmosphere. In other words, the flexible wall member 30' is disposed in the other of the pockets subdivided by the resilient deformable member 16'. The compensation chamber 34' is enclosed between the flexible wall member 30' and the outer sleeve 14'. The atmospheric chamber 19 is bounded by the resilient deformable member 16' and the flexible wall member 30' so as to be out of contact with the inner circumferential surfaces of the first and second sleeve sections 14'a and 14'b and the spacer section 14'c. A single piece of the resilient deformable member 16' and flexible wall 30' is bonded to the inner circumferential surfaces of the sleeve sections 14'a and 14'b by sulfurization. In this connection, the resilient deformable member 16' is so shaped as to have a pair of axially spaced annular sealing lips 44 and 46 projecting outward from the outer circumferential surface thereof. The spacer section 14'c is in the form of a split ring and is formed with the opening 38 through which the working chamber 18 communicates with the passageway 24. The spacer section 14'c is further formed with an opening 48 through which the passage 24 communicates with the compensation chamber 34'. More specifically, a blank for the spacer section 14'c is formed from a flat plate. The flat blank is then formed with the opening 48 and rolled or otherwise formed into a split ring. In assembly, the spacer section 14'c is placed around the resilient deformable member 16' and flexible wall member 30' by being stretched so that the resilient deformable member 16' and flexible wall member 30' pass through the separated ends of the spacer section 14'c. In this instance, the annular sealing lips 44 and 46 are placed between the matched axial ends of the sleeve sections 14'a and 14'b and the spacer section 14'c. The outer sleeve 14' is fitted in the bracket 20 together with the inner sleeve 12 and the resilient deformable member 16' and flexible wall member 30', allowing the sealing lips 44 and 46 to sealingly contact the inner circumferential surface of the bracket 20. In the foregoing, it is to be noted that each of the sealing lips 44 and 46 of the resilient deformable member 16' and the flexible wall member 30' provide a seal between the outer circumferential surface of the resilient member 16' and the resilient wall member 30' and the inner circumferential surface of the bracket 20 for thereby sealing the working chamber 18, compensating chamber 30' and the passageway 24 all together. In this connection, it will be understood that the atmospheric chamber 19 is fluidly separated from the inner circumferential surface of the spacer section 14'c by circumferential wall portions of the resilient deformable member 16' and flexible wall member 30' as well as the sealing lips 44 and 46. It is further to be noted that the spacer section 14'c makes it easier to form the opening 48 in the outer sleeve 14. It is still further to be noted that the spacer section 14'c is useful for easy and assured installation of the sleeve sections 14'a and 14'b in the bracket 20.

Claims: A hydraulically damped mounting device of the bushing type comprising: Concentric rigid inner (12) and outer sleeves (14') having a space therebetween; a resilient elastomeric member (16') within said space connecting said inner and outer sleeves (12,14') together and thereby sub-dividing that space into two pockets; a working chamber (18) in one of said pockets enclosed between said resilient member (16') and said outer sleeve (14'), said working chamber (18) containing a fluid; a flexible wall member (30') integral with said resilient member (16'), disposed in the other of said pockets; a compensation chamber (34') within the other said pocket enclosed between said flexible wall member (30') and said outer sleeve (14'); a generally tubular bracket (20) fitted on said outer sleeve (14'); and a passageway (24) defined between said bracket (20) and said outer sleeve (14') and communicating said working chamber (18) and said compensation chamber (34') to provide fluid communication therebetween characterized in that said outer sleeve (14') is axially separated to include first and second sleeve sections (14'a,14'b) and a spacer section (14'c) interposed between said first and second sleeve sections (14'a,14'b), said spacer section (14'c) being in the form of a split ring and having an opening (48) for providing fluid communication between said working chamber (18) and said passageway (24); and said resilient member (16') and flexible wall member (30') having a pair of axially spaced annular sealing lips (44,46) projecting outward from an outer circumferential surface, said sealing lips (44,46) being interposed between matched axial ends of said first and second sleeve sections (14'a,14'b) and said spacer section (14'c) and sealingly contacting an inner circumferential wall of said bracket (20), said sealing lips (44,46) provide a seal between the outer circumferential surface of the resilient member (16') and the resilient wall member (30') and the inner circumferential surface of the bracket (20) for thereby sealing the working chamber (18), the compensating chamber (30') and the passageway (24). The device according to claim 1 characterized by an atmospheric chamber (19) bound by said resilient member (16') and said flexible wall member (30') so as to be out of contact with the inner circumferential surfaces of said first and second sections (14'a,14'b) and said spacer section (14'c).

Inventors: IDE TAKANOBU, IDE, TAKANOBU
Applicants: NISSAN MOTOR, NISSAN MOTOR CO., LTD.
Application year: 1989
Main classification: F16F13
IPC codes: F16M7, F16F13, F02B61, B60K5