Expansion valve

Details Expansion valve Expansion valve

1999-02-08

2001-06-05

Tapolcal, William E. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000, C062S299000, C248S500000

Reexamination Certificate

active

06241157

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.
In the prior art, this type of expansion valve is used in the refrigeration cycle of an air conditioning device in vehicles, as disclosed in Japanese Laid-Open Patent Publication No. H9-26235.
FIG. 17
shows a vertical cross-sectional view of a widely used prior art expansion valve with an outline of the refrigeration cycle.
FIG. 18
is a schematic view of the valve body in the expansion valve, and
FIG. 19
is a front view of the expansion valve viewed from direction A of FIG.
17
. The expansion valve
10
comprises a valve body
30
made of aluminum alloy 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. 18 and 19
, reference number
50
shows 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.
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, comprising an entrance port
321
connected to the receiver
6
, and a valve chamber
35
connected to the entrance port
321
. 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
. The plug
39
is equipped with an o-ring
39
a
.
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 penetrates 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
according to the exit temperature of the evaporator
8
, and 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.
Further, the valve body
30
includes a narrow portion
30
b
having a thin width whose width size W
2
is reduced (narrowed) compared to the width size W
1
of the portion where the bolt holes
50
exist, at the lower portion corresponding to the first passage
32
which is opposite to the upper portion where the power element portion
36
is to be mounted. The narrow portion contributes to lighten the weight and to reduce the cost of the parts used for the valve body
30
.
The base-shape material (material formed to have the basic shape) of the valve body
30
is manufactured by an extrusion process of an aluminum alloy for example, and the bolt holes
50
are formed by a following drilling process.
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 housing 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 driving liquid into 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 transmitted to the compressor
4
exits.
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 chamber
36
c
and the upper pressure chamber
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
against the elastic force of the biasing means
32
d
in correspondence 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 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 the upper end of the operating shaft
37
f
, and the lower end of the operating shaft
37
f
contacts 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 t

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