Brakes – Internal-resistance motion retarder – Cylinder structure
Reexamination Certificate
1998-09-25
2001-09-04
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Cylinder structure
C188S299100, C188S318000
Reexamination Certificate
active
06283259
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to hydraulic shock absorbers, especially for use in vehicle suspension systems.
A known hydraulic shock absorber typically includes an inner working cylinder and an outer cylinder extending around the working cylinder so as to define a reservoir therebetween (see FIG.
9
). The outer cylinder has an annular collar to which a mounting plate is secured by welding. A damper mechanism is attached to the mounting plate and communicated with the working cylinder through sleeves which are, in turn, inserted through the mounting plate. A problem with the known hydraulic shock absorber is that metal particles ejected during the welding, known as spatter, are introduced into oil within the reservoir, thus resulting in malfunction of the damper mechanism. Removal of such metal particles is cumbersome. Another problem is that an expensive seam weld is required to maintain the seal integrity. Moreover, with a plurality of O-rings placed on the mounting plate, the damper mechanism is secured to the mounting plate to properly position the O-rings. If the O-rings are not properly positioned, oil leakage occurs.
Accordingly, it is an object of the present invention to provide a hydraulic shock absorber which allows a damper mechanism to be mounted to an outer cylinder without the use of welding and enables proper positioning of sealing elements.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a hydraulic shock absorber comprising an inner cylinder filled with a working oil, an outer cylinder extending around the inner cylinder so as to define a reservoir therebetween, a piston slidably disposed within the inner cylinder so as to divide the interior of the inner cylinder into an upper cylinder chamber and a lower cylinder chamber, a piston rod having one end connected to the piston and the other end extending out of the inner cylinder, oil passage means communicated with the interior of the inner cylinder and adapted to allow the working oil to flow therethrough as the piston is moved, a tubular member having a port and disposed between the inner cylinder and the outer cylinder so as to define therebetween annular oil passages which form a part of the oil passage means, damper means attached to the outer cylinder for controlling flow of the working oil through the oil passage means so as to produce a damping resistance, the outer cylinder including a mounting projection with a substantially flat top surface on which the damper means is secured, a sleeve for providing fluid communication between the oil passage means and the damper means, one end of the sleeve being inserted into the port of the tubular member, and the flanged end of the sleeve terminating at the top surface of the mounting projection, first sealing means placed between the one end of the sleeve and the port of the tubular member for providing a seal between the sleeve and the port, and second sealing means placed around the flanged end of the sleeve for providing a seal between the outer cylinder and the damper means.
This arrangement eliminates the need for an expensive seam weld and thus brings about a reduction in the fabrication cost of the entire hydraulic shock absorber. Also, there is substantially no risk that spatter or other foreign substance is introduced into the working oil within the reservoir.
The second sealing means may include a first sealing element vulcanized or otherwise secured between the flanged end of the sleeve and the top surface of the mounting projection, and a second sealing element vulcanized or otherwise secured between the flanged end of the sleeve and the damper means. This arrangement ensures proper positioning of the sealing elements and thus avoids oil leakage.
According to another aspect of the present invention, there is provided a hydraulic shock absorber comprising an inner cylinder filled with a working oil, an outer cylinder extending around the inner cylinder so as to define a reservoir therebetween, a piston slidably disposed within the inner cylinder so as to divide the interior of the inner cylinder into an upper cylinder chamber and a lower cylinder chamber, a piston rod having one end connected to the piston and the other end extending out of the inner cylinder, oil passage means communicated with the interior of the inner cylinder and adapted to allow the working oil to flow therethrough as the piston is moved, a tubular member having a port and disposed between the inner cylinder and the outer cylinder so as to define therebetween annular oil passages which form a part of the oil passage means, damper means attached to the outer cylinder for controlling flow of the working oil through the oil passage means so as to produce a damping resistance, the outer cylinder including a mounting projection with a substantially flat top surface on which the damper means is secured, a sleeve for providing fluid communication between the oil passage means and the damper means, one end of the sleeve being inserted into the port of the tubular member, and the flanged end of the sleeve terminating at the top surface of the mounting projection, and sealing means tightly fitted around the sleeve and having a generally cylindrical shape. The sealing means includes an enlarged end and a flanged end opposite the enlarged end, the enlarged end of the sealing means being fitted around the one end of the sleeve and sandwiched between the port and the one end of the sleeve to provide a seal therebetween. The flanged end of the sealing means is fitted around the flanged end of the sleeve and includes an annular inner lip and an annular outer lip, the annular inner lip being pressed against the damper means, and the outer lip being sandwiched between the flanged end of the sleeve and the top surface of the mounting projection.
The enlarged end of the sealing means has a pressure bearing area on which pressure is exerted by the working oil, and the inner lip of the sealing means has a pressure bearing area on which pressure is exerted by the working oil. Preferably, the pressure bearing area of the enlarged end is greater than the pressure bearing area of the inner lip. With this arrangement, the sealing means is biased toward the damper means to improve the seal integrity.
REFERENCES:
patent: 5282645 (1994-02-01), Spakowski et al.
patent: 5301412 (1994-04-01), Hahn et al.
patent: 5467851 (1995-11-01), Handke et al.
patent: 5649611 (1997-07-01), Nakadate
patent: 5740890 (1998-04-01), Forster
patent: 5901820 (1999-05-01), Kashiwago et al.
patent: 5960915 (1999-10-01), Nezu et al.
patent: 5975586 (1999-11-01), Pradel
patent: 5988331 (1999-11-01), Schiffler
Oberleitner Robert J.
Siconolfi Robert A.
Tokico Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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