Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
2002-04-23
2003-12-30
Lee, Kevin (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S532000, C137S533110
Reexamination Certificate
active
06668862
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a fluid bearing mechanism for antifriction between a piston and a cylinder of a reciprocating compressor or the like, particularly to a one-way valve for providing or interrupting the communication between the inside and the outside of a compression chamber for use with such compressor.
b) Prior Art
Conventional fluid bearing mechanisms are illustrated in
FIGS. 6
to
8
. The fluid bearing mechanism comprises: a cylinder
101
, a reciprocating piston
102
inserted into the cylinder
101
with a slight clearance G provided therebetween; a hollow interior
102
a
formed inside the piston
102
; a one-way valve
103
provided at a distal end of the piston
102
, said one-way valve
103
providing the communication between a space
101
a
within the cylinder
101
and the hollow interior
102
a
; and small holes defined through a side surface
102
b
of the piston
102
, said small holes
104
providing the communication between the clearance G and the hollow interior
102
a
. For the above-mentioned one-way valve
103
, U.S. Pat. No. 5,461,859, for example, discloses a structure of one of conventional one-way valves for that purpose.
The conventional one-way valve
103
comprises a valve base
105
, a reed
106
, a reed retainer
107
, and a fastening screw
108
as illustrated in FIG.
8
. The valve base
105
is formed with a communication hole
109
which provides the communication between the space
101
a
within the cylinder and the hollow interior
102
a
when it is mounted to the piston
102
, while the reed
106
and the reed retainer
107
are fixed by the fastening screw
108
in the vicinity of an opening
109
a
of the communication hole
109
located adjacent to the hollow interior
102
a.
In a state where the piston
102
is stationary, the reed
106
is allowed to close the opening
109
a
by abutting against an abutting surface
105
a
around the opening
109
a
. During the advance trip of the piston
102
within the cylinder
101
, pressure difference between the space
101
a
within the cylinder
101
and the hollow interior
102
a
urges a gas inside the space
101
a
to pass through the commutation hole
109
to bend the reed
106
, flowing through the opening
109
a
into the hollow interior
102
a
, and then flowing out of the small holes
104
into the clearance G. At this moment, excessive bending of the reed
106
is prevented due to the aforesaid reed retainer
107
. Thus, the gas flowing out into the clearance G provides the antifriction between the cylinder
101
and the piston
102
. On the other hand, during the return trip of the piston
102
within the cylinder
101
, the pressure difference between the space
101
a
within the cylinder and the hollow interior
102
a
as well as the restoring force by the reed
106
allow the opening
109
a
to be closed by the reed
106
. In this way, the gas inside the space
101
a
within the cylinder flows in one direction only.
According to the conventional one-way valve
103
of the fluid bearing mechanism, however, it was imperative to process the respective surfaces of the reed
106
and the abutting surface
105
a
smoothly and accurately enough to prevent the gas from flowing backwardly from between the reed
106
and the abutting surface
105
a
. Further, as the reed
106
is made from a thin metal plate in order to bend it at a high speed, there has been a problem that it is likely to be deformed at the time of processing or mounting process.
SUMMARY OF THE INVENTION
To eliminate the above problems, it is a main object of the invention to provide a fluid bearing mechanism using a one-way valve, which is structured so simply that high processing accuracy is not required, and which is at the same time easy to assemble, with high reliability.
To attain the above objects, there is provided from a first aspect of the invention, a fluid bearing mechanism which comprises: a cylinder; a piston positioned inside the cylinder, having a side surface, end faces and a hollow interior formed therein side, said piston including small holes defined through the side surface for communicating the hollow interior with an exterior thereof; a one-way valve provided between the end face and the hollow interior of said piston, said one-way valve allowing a gas to flow in one direction only, wherein said one-way valve comprises: a cylindrical body provided in parallel with an axial direction of said piston; an abutting portion provided along an inner periphery of said cylindrical body, said abutting portion protruding inwardly, formed with a small communication hole in a substantial center thereof; a moveable element which is moveable inside said cylindrical body in an axial direction thereof; and a retaining body for retaining said moveable element between said abutting portion and itself inside said cylindrical body, said retaining body including a ventilation groove for communicating an inside with an outside of said cylindrical body
According to the first aspect of the invention, when the piston is moved to the compressing direction inside the cylinder, the moveable element is urged toward the inside of the piston, due to the inner pressure of the cylinder and its inertia, so that the small communication hole is opened, thus allowing the gas inside the cylinder to flow from the small communication hole of the one-way valve, through the ventilation grooves into the hollow interior of the piston, and then to flow through the small holes into the clearance between the piston and the cylinder. As a result, the clearance between the piston and the cylinder is insured to keep them away from each other. Further, when the piston inside the cylinder is moved to the expanding direction, the moveable element is reversely shifted toward the outside of the piston so that the small communication hole is closed, whereby the gas is prevented from flowing out into the cylinder, through the hollow interior of the piston and the clearance between the piston and the cylinder.
According to a second aspect of the invention, there is provided a fluid bearing mechanism according to the first aspect, wherein the retaining body is made of an elastic material so that the abutting portion, moveable element and retaining body are allowed to abut to each other at least when the piston is in a stationary state. Thus, when the piston is in a stationary state, the moveable element abuts to the abutting portion to close the small communication hole, while if the piston is shifted toward the compressing direction, the retaining body is elastically deformed due to the force applied to the moveable element, so that the moveable element is moved toward the inside of the piston to thereby open the small communication hole.
According to a third aspect of the invention, there is provided a fluid bearing mechanism according to one of the foregoing aspects, wherein at least the surface of either the moveable element or the abutting portion is made of an elastic material. Thus, when the abutting portion abuts to the moveable element, either the moveable element or the abutting portion is elastically deformed so that not only are they contacted by each other more closely but also the impact developed when they comes into collision with each other is absorbed.
According to a fourth aspect of the invention, there is provided a fluid bearing mechanism according to the first or the second aspect, wherein an abutting surface of said abutting portion is formed concavely conical while an abutting surface of said moveable element opposing to said abutting portion is formed convexly conical with an apex angle of the former being substantially equal to that of the latter. Thus, when they abut to each other, they are contacted by each other over an entire surface thereof, thereby preventing the leakage of gas from the small communication hole.
According to a further aspect of the invention, there is provided a fluid bearing mechanism, which comprises: a cylinder; a piston positioned insid
Maezawa Kazuo
Minagawa Takayuki
Urasawa Hideto
Akerman & Senterfitt
Lee Kevin
Twinbird Corporation
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