Expansible chamber devices – Piston – Side wall portion includes peripheral axially extending...
Patent
1994-12-19
1996-05-28
Look, Edward K.
Expansible chamber devices
Piston
Side wall portion includes peripheral axially extending...
92249, 92155, F16J 900
Patent
active
055200923
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a piston of a shock absorber as may be used in an automobile, for example.
BACKGROUND OF THE PRIOR ART
A piston of a shock absorber as used in an automobile or the like in the art is constructed in the following manner: Specifically, a piston of a shock absorber is known (see Japanese Laid-Open Patent Application No. 82,072/1986, for example) which comprises a cylindrical piston body, and a piston ring formed of a resin and covering the outer peripheral surface of the piston body. At a given axial location or locations, the outer periphery of the piston body is formed with an engaging groove or grooves, which are engaged by an annular projection or projections formed around the inner periphery of the piston ring while the outer periphery of the piston body is formed with a receiving groove toward its one end, in which a bend formed on one end of the piston ring is received. A piston having such a covering over the outer peripheral surface thereof and a method of manufacturing same are also known (see, for example, U.S. Pat. No. 3,212,411).
However, in the piston disclosed in the former, both end faces which define the receiving groove are tapered surfaces, and the bend is disposed in alignment with a first end face while the tip of the bend is disposed in a corner which is formed by a second end face and the bottom surface. Accordingly, with such a conventional arrangement, there is a disadvantage that because the second end face is a tapered surface, the tip of the bend tends to be disengaged from the receiving groove along the tapered surface.
SUMMARY OF THE INVENTION
In view of the foregoing, in a piston for a shock absorber as mentioned above, in accordance with the invention, the receiving groove comprises a first end face which is located nearest the engaging groove, a second end face disposed in opposing relationship with the first end face and extending in a direction orthogonal to the axis of the piston body, and a bottom surface which connects the first and the second end face together. The tip of the bend of the piston ring is disposed in abutment against a corner defined by the second end face and the bottom surface, thus receiving the bend of the piston ring in the receiving groove
With this construction, the tip of the bend abuts against the corner, and since the second end face which defines the corner extends in a direction orthogonal to the axis of the piston body, the tip of the bend is not likely to move radially outward from its position within the corner.
Accordingly, as compared with the prior art in which the send end face comprises a tapered surface, a disengagement of the bend from the receiving groove is not likely to occur.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross section of one embodiment of the invention as located above a centerline; and
FIG. 2 is a cross section illustrating a process of assembling a piston ring 5 on a piston body 4.
DETAILED DESCRIPTION
The invention will now be described with reference to an embodiment shown in the drawings. In FIG. 1, 1 represents a piston for a shock absorber of an automobile, which is connected to an end of a rod 2 for reciprocating movement within a cylinder 3.
The piston 1 comprises a cylindrical piston body 4, and a piston ring 5 which is formed of tetrafluoride resin and covering the outer periphery of the piston body 4. The tetrafluoride resin may contain an additive, for example, 10.about.20 wt % of graphite and/or carbon.
In its axially median region, the outer periphery of the piston body 4 has a greater diameter portion 4c having a greater diameter than its opposite ends 4a, 4b. Annular grooves having an equal depth and width are formed in the greater diameter portion 4c at an equal axial spacing, and are used as engaging grooves 4d. On the other hand, a plurality of annular projections 5a are formed around the inner periphery of the piston ring 5 in registry with the locations of the respective engaging grooves 4d, and these annular projections 5a are engaged w
REFERENCES:
patent: 3212411 (1965-10-01), Storms
patent: 3842717 (1974-10-01), Prescott
patent: 4539895 (1985-09-01), Tanaka et al.
patent: 4676143 (1987-06-01), Nomura et al.
Iida Masatake
Ohkouchi Teruhito
Look Edward K.
Taiho Kogyo Co. Ltd.
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