Expansion valve

Details Expansion valve Expansion valve

1999-02-10

2002-05-28

Tapolcai, William E. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000

Reexamination Certificate

active

06394360

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an expansion valve for controlling the flow rate of a refrigerant to be supplied to an evaporator in a refrigeration cycle of a refrigerator, an air conditioning device and so on.
This type of expansion valve is used in the refrigeration cycle of an air conditioning device in vehicles and the like, as well-known in the prior art.
FIG. 4
shows one example of a vertical cross-sectional view of a widely used prior art expansion valve together with an outline of the refrigeration cycle.
FIG. 5
is a schematic view of the valve body in the expansion valve, and
FIG. 6
is a front view of the expansion valve of
FIG. 4
viewed from direction A. The expansion valve
10
comprises a valve body
30
made of aluminum and having a substantially prismatic shape, to which are formed a first passage
32
of a refrigerant pipe
11
in the refrigeration cycle mounted in the portion from the refrigerant exit of a condenser
5
through a receiver
6
toward the refrigerant entrance of an evaporator
8
through which a liquid-phase refrigerant travels, and a second passage
34
of the refrigerant pipe
11
mounted in the portion from the refrigerant exit of the evaporator
8
toward the refrigerant entrance of a compressor
4
through which a gas-phase refrigerant travels. The passages are formed so that one passage is positioned above the other passage with a distance in between. Further, in
FIGS. 5 and 6
, reference number
50
show bolt inserting holes for mounting the expansion valve
10
.
On the first passage
32
is formed an orifice
32
a
where adiabatic expansion of the liquid-phase refrigerant supplied from the refrigerant exit of the receiver
6
is to be performed. On the entrance side of the orifice
32
a
or upper stream side of the first passage is formed a valve seat, and a spherical valve means
32
b
supported by the valve member
32
c
from the upper stream side is positioned on the valve seat. The valve member
32
c
is fixed to the valve means by welding, and positioned between a biasing means
32
d
of a compression coil spring and the like, thereby transmitting the bias force of the biasing means
32
d
to the valve means
32
b
, and as a result, biasing the valve means
32
b
toward the direction approaching the valve seat. By the above-mentioned operation, the opening of the valve is adjusted.
The first passage
32
to which the liquid-phase refrigerant from the receiver
6
is introduced acts as the passage for the liquid-phase refrigerant. An entrance port
321
connected to the receiver
6
and a valve chamber
35
connected to the entrance port
321
is formed to the valve body
30
, wherein a valve means
32
b
is positioned inside the valve chamber
35
. An exit port
322
is connected to the evaporator
8
. The valve chamber
35
is a chamber with a bottom formed coaxially with the orifice
32
a
, and is sealed by a plug
39
, which acts as an adjusting screw. The plug
39
is movably screwed in the advancing or retreating direction onto a mounting hole
39
′ communicated to the valve chamber
35
, for controlling the pressurizing force of the coil spring. The plug
39
is equipped with an o-ring
39
a
, so as to secure the sealed state between the valve body
30
.
Moreover, the valve body
30
is equipped with a small radius hole
37
and a large radius hole
38
, which is larger than the hole
37
, which penetrate through the second passage
34
and are positioned coaxial to the orifice
32
a
, so as to provide driving force to the valve means
32
b
for opening or closing the orifice
32
a
according to the exit temperature of the evaporator
8
. On the upper end of the valve body
30
is formed a screw hole
361
to which a power element portion
36
acting as a heat sensing portion is fixed.
The power element portion
36
comprises a diaphragm
36
a
made of stainless steel, an upper cover
36
d
and a lower cover
36
h
welded to each other with the diaphragm
36
a
positioned in between so as to each define an upper pressure housing
36
b
and a lower pressure housing
36
c
forming two sealed housings on the upper and lower areas of the diaphragm
36
a
, and a sealed tube
36
i
for sealing a predetermined refrigerant working as a diaphragm drive liquid into the interior space communicated to the upper pressure housing
36
b
, wherein the lower cover
36
h
is screwed onto the screw hole
361
with a packing
40
. The lower pressure housing
36
c
is communicated to the second passage
34
through a pressure-equalizing hole
36
e
formed coaxial to the center axis of the orifice
32
a
. The refrigerant vapor from the evaporator
8
flows through the second passage
34
, and therefore, the second passage
34
acts as a passage for the gas-phase refrigerant, and the pressure of the refrigerant gas is loaded to the lower pressure housing
36
c
through the pressure-equalizing hole
36
e
. Further, reference number
342
represents an entrance port from which the refrigerant transmitted from the evaporator
8
enters, and
341
represents an exit port from which the refrigerant to be transmitted to the compressor
4
exits. In
FIGS. 5 and 6
, the sealed tube
36
i
is omitted from the drawing.
Inside the lower pressure housing
36
c
contacting the diaphragm
36
a
is formed an aluminum heat sensing shaft
36
f
positioned slidably inside the large radius hole
38
penetrating the second passage
34
, so as to transmit the refrigerant exit temperature of the evaporator
8
to the lower pressure housing
36
c
and to slide inside the large radius hole
38
in correspondence to the displacement of the diaphragm
36
a
accompanied by the difference in pressure between the lower pressure housing
36
c
and the upper pressure housing
36
b
in order to provide drive force, and a stainless steel operating shaft
37
f
having a smaller diameter than the heat sensing shaft
36
f
is positioned slidably inside the small radius hole
37
for pressing the valve means
32
b
in resistance to the elastic force of the biasing means
32
d
according to the displacement of the heat sensing shaft
36
f
, wherein the heat sensing shaft
36
f
is equipped with a sealing member, for example, an o-ring
36
g
, so as to secure the seal between the first passage
32
and the second passage
34
. The upper end of the heat sensing shaft
36
f
contacts to the lower surface of the diaphragm
36
a
as the receiving portion of the diaphragm
36
a
, the lower end of the heat sensing shaft
36
f
contacts to the upper end of the operating shaft
37
f
, and the lower end of the operating shaft
37
f
contacts to the valve means
32
b
, wherein the heat sensing shaft
36
f
together with the operating shaft
37
f
constitute a valve drive shaft. Accordingly, the valve drive shaft extending from the lower surface of the diaphragm
36
a
to the orifice
32
a
of the first passage
32
is positioned coaxially inside the pressure-equalizing hole
36
e
. Further, a portion
37
e
of the operating shaft
37
f
is formed narrower than the inner diameter of the orifice
32
a
, which penetrates through the orifice
32
a
, and the refrigerant passes through the orifice
32
a.
A known diaphragm drive liquid is filled inside the upper pressure housing
36
b
of the pressure housing
36
d
, and through the diaphragm
36
a
and the valve drive shaft exposed to the second passage
34
and the pressure equalizing hole
36
e
communicated to the second passage
34
, the heat of the refrigerant vapor travelling through the second passage
34
from the refrigerant exit of the evaporator
8
is transmitted to the diaphragm drive liquid.
In correspondence to the heat being transmitted as above, the diaphragm drive liquid inside the upper pressure housing
36
b
turns into gas, the pressure thereof being loaded to the upper surface of the diaphragm
36
a
. The diaphragm
36
a
is displaced to the vertical direction according to the difference between the pressure of the diaphragm drive gas loaded to the upper surface thereof and the pressur

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