Brakes – Internal-resistance motion retarder – Having a thrust member with a variable volume chamber
Reexamination Certificate
1998-08-12
2001-02-06
Oberleitner, Robert J. (Department: 3613)
Brakes
Internal-resistance motion retarder
Having a thrust member with a variable volume chamber
C188S297000, C267S064260
Reexamination Certificate
active
06182806
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic shock absorber, which has an improved structure of a gas chamber defined by a partition wall member such as a free piston.
2. Description of the Related Art
For hydraulic shock absorbers used in four-wheeled vehicles and two-wheeled vehicles, there has been proposed an erect strut type structure as disclosed in Japanese Utility Model Application Laid-Open (JP-U) No. 51-129988, and an inverted strut type structure shown in FIG.
5
. As shown in the prior art,
FIG. 5
, the hydraulic shock absorber
1
has a cylinder
2
is filled with a hydraulic fluid, and a piston
3
is slidably provided therein. The piston
3
is provided with a damping valve
4
for generating a damping force, and is connected to one end of a piston rod
5
. Further, in order to absorb the capacity resulting from the piston rod
5
reciprocating in the cylinder
2
, the cylinder
2
is formed with a gas chamber
6
, and a free piston
8
partitioning the gas chamber
6
and an oil chamber
7
is slidably provided in the cylinder
2
.
On the inner circumferential surface of the cylinder
2
, in the slidable range Y of the free piston
8
is grease lubrication. In the slidable range X of the piston
3
is a hydraulic fluid lubrication (oil lubrication). Thus, in order to improve the responsibility of free piston
8
and a resistant abrasion performance of the free piston
8
and the cylinder
2
, a surface roughness (coarseness) of the slidable range Y of the free piston
8
must be twice the degree as the surface roughness of the slidable range X of the piston
3
. For this reason, there is a problem of increasing the number of processes for machining the cylinder
2
.
Further, in the cylinder
2
, the slidable range Y of the free piston
8
is set outside the slidable range X of the piston
3
; for this reason, a stopper
9
for stopping a sliding motion of the free piston
8
must be fixed in the cylinder
2
. This increases the number of processes for machining the cylinder
2
.
Further, a gas is encapsulated in the cylinder
2
, and thereafter, a hydraulic fluid is filled therein, and thus, the aforesaid hydraulic shock absorber
1
is assembled. For this reason, an assembling apparatus becomes complicate, and is made into a large size, and in addition, the number of processes for assembling the hydraulic shock absorber
1
.
Moreover, in the aforesaid hydraulic shock absorber
1
, a stud
2
A for vehicle body attachment is fixed onto the cylinder
2
by bending the end portion of the cylinder
2
. When a lateral direction (direction perpendicular to an axis of the hydraulic shock absorber) load (torsion (twisting) load F) is applied (acts) onto the stud
2
A, an insertion length of the stud
2
A with respect to the cylinder
2
is short. For this reason, there is a need of increasing a strength of bending the stud
2
A to the end portion of the cylinder
2
in order to secure a strength against the torsion load F.
SUMMARY OF THE INVENTION
The present invention has been made in view of the aforesaid problems in the prior art. It is, therefore, an object of the present invention to provide a hydraulic shock absorber which can reduce the number of machining processes and the number of assembling processes.
To achieve the above object, the present invention provides a hydraulic shock absorber comprises; a cylinder which is filled with a hydraulic fluid; a piston connected to one end of a piston rod, and which is slidably disposed in the cylinder; and a partition wall member which is slidably disposed in the cylinder so as to partition the cylinder into a gas chamber and an oil chamber, wherein a gas chamber cartridge inserted into one side of the cylinder so as to be fixed thereto, the partition wall member is slidably disposed in the gas chamber case of the gas chamber cartridge, defining one chamber partitioned by the partition wall member of the gas chamber case as the gas chamber encloses a gas therein, and defining the other chamber partitioned by the partition wall member of the gas chamber case as connected to the oil chamber on the other side of the cylinder.
REFERENCES:
patent: 3750855 (1973-08-01), Peddinghaus
patent: 3955655 (1976-05-01), Pornin
patent: 4720085 (1988-01-01), Shinbori et al.
patent: 4821983 (1989-04-01), Aubry et al.
patent: 5797594 (1998-08-01), Sekine et al.
patent: 51129988 (1950-03-01), None
Oberleitner Robert J.
Orum & Roth
Showa Corporation
Williams Thomas J.
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