Expansion valve

Details Expansion valve Expansion valve

1999-11-12

2001-03-27

Tapolcai, William E. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000

Reexamination Certificate

active

06206294

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to expansion valves and, more particularly, to expansion valves used for refrigerant utilized in refrigeration cycles of air conditioners, refrigeration devices and the like.
BACKGROUND OF THE INVENTION
In the prior art, these kinds of expansion valves were used in refrigeration cycles of air conditioners in automobiles and the like.
FIG. 5
shows a prior art expansion valve in cross section together with an explanatory view of the refrigeration cycle. The expansion valve
10
includes a valve body
30
formed of prismatic-shaped aluminum comprising a refrigerant duct
11
of the refrigeration cycle having a first path
32
and a second path
34
, the one path placed above the other with a distance in between. The first path
32
is for a liquid-phase refrigerant passing through a refrigerant exit of a condenser
5
through a receiver
6
to a refrigerant entrance of an evaporator
8
. The second path
34
is for a liquid-phase refrigerant passing through the refrigerant exit of the evaporator
8
toward a refrigerant entrance of a compressor
4
.
An orifice
32
a
for the adiabatic expansion of the liquid refrigerant supplied from the refrigerant exit of the receiver
6
is formed on the first path
32
. The orifice
32
a
is positioned on the vertical center line taken along the longitudinal axis of the valve body
30
. A valve seat is formed on the entrance of the orifice
32
a
, and a valve means
32
b
supported by a valve member
32
c
. The valve means
32
b
and the valve member
32
c
are welded and fixed together. The valve member
32
c
is fixed onto the valve means
32
b
and is also forced by a spring means
32
d
, for example, a compression coil spring.
The first path
32
where the liquid refrigerant from receiver
6
is introduced is a path of the liquid refrigerant, and is equipped with an entrance port
321
and a valve room
35
connected thereto. The valve room
35
is a room with a floor portion formed on the same axis as the center line of the orifice
32
a
, and is sealed by a plug
39
.
Further, in order to supply drive force to the valve body
32
b
according to an exit temperature of the evaporator
8
, a small hole
37
and a large hole
38
having a greater diameter than the hole
37
is formed on said center line axis perforating through the second path
34
. A screw hole
361
for fixing a power element member
36
working as a heat sensor is formed on the upper end of the valve body
30
.
The power element member
36
is comprised of a stainless steel diaphragm
36
a
, an upper cover
36
d
and a lower cover
36
h
each defining an upper pressure activate chamber
36
b
and a lower pressure activate chamber
36
c
forming two sealed chambers above and under the diaphragm
36
a
, and a tube
36
i
for enclosing a predetermined refrigerant working as a diaphragm driver liquid into said upper pressure activate chamber, wherein said lower pressure activate chamber
36
c
is connected to said second path
34
via a pressure hole
36
e
formed to have the same center as the center line axis of the orifice
32
a
. A refrigerant vapor from the evaporator
8
is flown through the second path
34
. The second path
34
is a path for gas phase refrigerant, and the pressure of said refrigerant vapor is added to said lower pressure activate chamber
36
c
via the pressure hole
36
e.
Further, inside the lower pressure activate chamber
36
c
is a valve member driving shaft comprising a heat sensing shaft
36
f
and an activating shaft
37
f
. The heat sensing shaft
36
f
made of aluminum is movably positioned through the second path
34
inside the large hole
38
and contacting the diaphragm
36
a
so as to transmit the refrigerant exit temperature of the evaporator
8
to the lower pressure activate chamber
36
c
, and to provide driving force in response to the displacement of the diaphragm
36
a
according to the pressure difference between the upper pressure activate chamber
36
b
and the lower pressure activate chamber
36
c
by moving inside the large hole
38
. The activating shaft
37
f
made of stainless steel is movably positioned inside the small hole
37
and provides pressure to the valve means
32
b
against the spring force of the spring means
32
d
according to the displacement of the heat sensing shaft
36
f
. The heat sensing shaft
36
f
is equipped with a sealing member, for example, an O ring
36
g
, so as to provide seal between the first path
32
and the second path
34
. The heat sensing shaft
36
f
and the activating shaft
37
f
are contacting one another, and the activating shaft
37
f
is in contact with the valve member
32
b
. Therefore, in the pressure hole
36
e
, a valve member driving shaft extending from the lower surface of the diaphragm
36
a
to the orifice
32
a
of the first path
32
is positioned having the same center axis as the pressure hole.
A known diaphragm driving liquid is filled inside the upper pressure activating chamber
36
b
placed above a pressure activate housing
36
d
, and the heat of the refrigerant vapor from the refrigerant exit of the evaporator
8
flowing through the second path
34
via the diaphragm
36
a
is transmitted to the diaphragm driving liquid.
The diaphragm driving liquid inside the upper pressure activate chamber
36
b
adds pressure to the upper surface of the diaphragm
36
a
by turning into gas in correspondence to said heat transmitted thereto. The diaphragm
36
a
is displaced in the upper and lower direction according to the difference between the pressure of the diaphragm driving gas added to the upper surface thereto and the pressure added to the lower surface thereto.
The displacement of the center portion of the diaphragm
36
a
to the upper and lower direction is transmitted to the valve member
32
b
via the valve member driving shaft and moves the valve member
32
b
close to or away from the valve seat of the orifice
32
a
. As a result, the refrigerant flow rate is controlled.
That is, the gas phase refrigerant temperature of the exit side of the evaporator
8
is transmitted to the upper pressure activate chamber
36
b
, and according to said temperature, the pressure inside the upper pressure activate chamber
36
b
changes, and the exit temperature of the evaporator
8
rises. When the heat load of the evaporator rises, the pressure inside the upper pressure activate chamber
36
b
rises, and accordingly, the heat sensing shaft
36
f
or valve member driving shaft is moved in the downward direction and pushes down the valve means
32
b
via the activating shaft
37
, resulting in a wider opening of the orifice
32
a
. This increases the supply rate of the refrigerant to the evaporator, and lowers the temperature of the evaporator
8
. In reverse, when the exit temperature of the evaporator
8
decreases and the heat load of the evaporator decreases, the valve means
32
b
is driven in the opposite direction, resulting in a smaller opening of the orifice
32
a
. The supply rate of the refrigerant to the evaporator decreases, and the temperature of the evaporator
8
rises.
In a refrigeration system using such expansion valve, a so-called hunting phenomenon wherein over supply and under supply of the refrigerant to the evaporator repeats in a short term is known. This happens when the expansion valve is influenced by the environment temperature, and, for example, the non-evaporated liquid refrigerant is adhered to the heat sensing shaft of the expansion valve. This is sensed as a temperature change, and the change of heat load of the evaporator occurs, resulting an oversensitive valve movement.
When such hunting phenomenon occurs, it not only decreases the ability of the refrigeration system as a whole, but also affects the compressor by the return of liquid to said compressor.
The present applicant suggested an expansion valve shown in
FIG. 6
as Japanese Patent Application No. H7-325357. This expansion valve
10
includes a resin
101
having low heat transfer rate being inserted to and contac

Affiliated with

Also associated with

Rating

Expansion valve does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Expansion valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Expansion valve will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2474530