Fluid handling – Diverse fluid containing pressure systems – Fluid separating traps or vents
Reexamination Certificate
2000-06-20
2001-11-20
Lee, Kevin (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Fluid separating traps or vents
Reexamination Certificate
active
06318401
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an air valve assembly for hydraulic jack, and more particularly to such an air valve assembly, which can be easily installed in the oil cylinder of a hydraulic jack keep the internal pressure of the hydraulic jack in balance with the atmospheric pressure, and to prevent hydraulic oil from leaking out.
(b) Description of the Prior Art
The oil cylinder structure (see
FIG. 2
) of a conventional hydraulic jack (see
FIG. 1
) is generally comprised of an outer oil cylinder
10
, an inner oil cylinder
20
, a movable rod member
30
, and a valve block
40
. The inner oil cylinder
20
is fixedly mounted inside the outer oil cylinder
10
. The rod member
30
is installed in the inner oil cylinder
20
, and partially extended out of the front side of the outer oil cylinder
10
. The valve block
40
is fixedly fastened to the outer oil cylinder
10
and the inner oil cylinder
20
at the rear side. Further, hydraulic oil is filled in the outer oil cylinder
10
. When in use, the valve block
40
is operated to cause a suction force, which sucks hydraulic oil from the outer oil cylinder
10
into the inner oil cylinder
20
. When hydraulic oil is delivered from the outer oil cylinder
10
to the inner oil cylinder
20
, the rod member
30
is moved forwards to lift the load. In order to let hydraulic oil pass between the outer oil cylinder
10
and the inner oil cylinder
20
, an air hole
101
is provided at the peripheral wall of the outer oil cylinder
10
for enabling outside air to pass into the outer oil cylinder
10
so that hydraulic oil can be completely drawn out of the outer oil cylinder
10
into the inner oil cylinder
20
. However, hydraulic oil may leak out of the air hole
101
when returning to the outer oil cylinder
10
. In order to eliminate this problem, a plug
102
or manual air valve may be used to seal the air hole
101
. However, this structure of plug
102
cannot absolutely eliminate oil leakage. When a manual air valve is used, it must be opened upon each use of the hydraulic jack, and then closed after each use of the hydraulic jack. There is another conventional design, which provides a relatively bigger volume to hold hydraulic oil and air, preventing insufficient hydraulic oil suction action due to insufficient pressure difference at the end of the stroke. This design is an enclosed design. The main drawback of this design is its bulky size.
SUMMARY OF THE INVENTION
The present invention has been accomplished to provide an air valve assembly for hydraulic jack, which eliminates the aforesaid drawbacks. According to one aspect of the present invention, the air valve assembly comprises a valve block, the valve block having a threaded front neck for mounting, a longitudinal center through hole, and a radial air hole in communication between the longitudinal center through hole and the atmosphere, an air guide block mounted inside the valve block, the air guide block having a spiral groove around the periphery in communication between two distal ends of the longitudinal center through hole of the valve block, a stop plate fixedly mounted inside the valve block above the air guide block, the stop plate having a center round hole for the passing of flow means, and a felt element fixedly mounted inside the valve block and attached to the stop plate at the top and aimed at the radial through hole of the valve block to stop hydraulic oil from passing out of the center round hole of the stop plate and to let outside air pass from the radial through hole of the valve block through the center round hole of the stop plate into the space inside of the valve block below the stop plate. According to another aspect of the present invention, a rubber retainer is provided and secured to the valve block to hold a screw bolt adapted for mounting in the air hole on the outer oil cylinder of the hydraulic jack to seal the air hole when the hydraulic jack is not in use. The rubber retainer comprises a first O-ring fastened to the threaded neck of the valve block, a second O-ring fastened to the screw bolt, and a wire rod connected between the first O-ring and the second O-ring.
REFERENCES:
patent: 2734521 (1956-02-01), Hencken
patent: 2776671 (1957-01-01), Ferguson
patent: 3086542 (1963-04-01), Mosier
patent: 3631877 (1972-01-01), Barosko
patent: 4467827 (1984-08-01), Pasbrig
Lee Kevin
Shinn Fu Corporation
Varndell & Varndell PLLC
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