Thermal expansion valve

Details Thermal expansion valve Thermal expansion valve

2000-07-19

2003-04-01

Tapolcai, William E. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000

Reexamination Certificate

active

06540149

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a thermal expansion valve used for controlling the flow of the refrigerant and for reducing the pressure of the refrigerant being supplied to the evaporator in a refrigeration cycle.
DESCRIPTION OF THE RELATED ART
A conventionally-used thermal expansion valve is formed as shown in
FIGS. 4 and 5
.
In
FIG. 4
, a prismatic-shaped valve body
510
comprises a first refrigerant passage
514
to which an orifice
516
is formed, and a second refrigerant passage
519
, which are formed independently from each other. One end of the first refrigerant passage
514
is communicated to the entrance of an evaporator
515
, and the exit of the evaporator
515
is communicated through the second refrigerant passage
519
, a compressor
511
, a condenser
512
, and a receiver
513
to the other end of the first refrigerant passage
514
. A valve chamber
524
communicated to the first refrigerant passage
514
is equipped with a bias means
517
, which in the drawing is a bias spring for biasing a spherical valve member
518
. The valve member
518
is driven to contact to or separate from an orifice
516
. The valve chamber
524
is sealed by a plug
525
, and the valve member
518
is biased through a support unit
526
. A power element
520
with a diaphragm
522
is fixed to the valve body
510
in a position adjacent to the second refrigerant passage
519
. An upper chamber
520
a
formed to the power element
520
and defined by a diaphragm
522
is air-tightly sealed, and within the upper chamber is sealed a temperature-responsive working fluid.
A short pipe
521
extending from the upper chamber
520
a
of the power element
520
is used for the deaeration of the upper chamber
520
a
and the filling of the temperature-responsive working fluid into the chamber
520
a
, before the end portion of the pipe is sealed. The extending end of a valve drive member
523
working as a temperature sensing/transmitting member which starts at the valve member
518
and penetrates through the second refrigerant passage
519
within the valve body
510
is contacted to the diaphragm
522
inside a lower chamber
520
b
of the power element
520
. The valve drive member
523
is formed of a material having a large heat capacity, and it transmits the temperature of the refrigerant vapor flowing from the exit of the evaporator
515
through the second refrigerant passage
519
, to the temperature-responsive working fluid sealed inside the upper chamber
520
a
of the power element
520
, which generates a working gas having a pressure corresponding to the temperature being transmitted thereto. The lower chamber
520
b
is communicated through the gap around the valve drive member
523
to the second refrigerant passage
519
within the valve body
510
.
Accordingly, the diaphragm
522
of the power element
520
adjusts the valve opening of the valve member
518
against the orifice
516
(in other words, the quantity of flow of the liquid-phase refrigerant entering the evaporator) through the valve drive member
523
under the influence of the bias force provided by the bias means
517
of the valve member
518
, according to the difference in pressure of the working gas of the temperature-responsive working fluid inside the upper chamber
520
a
of the diaphragm and the pressure of the refrigerant vapor at the exit of the evaporator
515
within the lower chamber
520
b.
According to the thermal expansion valve of the prior art, a problem such as a hunting phenomenon was likely to occur, in which the valve member repeats an opening/closing movement.
In a prior art example aimed at preventing such hunting from occurring, an adsorbent such as an activated carbon is sealed inside a hollow valve driving member.
FIG. 5
is a vertical cross-sectional view showing the prior art thermal expansion valve in which an activated carbon is sealed therein. The basic composition of the valve shown in
FIG. 5
is substantially the same as that shown in
FIG. 4
, except for the structure of a diaphragm and a valve drive member acting as a temperature sensing/pressure transmitting member. In
FIG. 5
, the thermal expansion valve includes a prismatic-shaped valve body
50
, and the valve body
50
comprises a port
52
through which a liquid-phase refrigerant flowing from a condenser
512
via a receiver tank
513
is introduced to a first passage
62
, a port
58
for sending out the refrigerant from the first passage
62
to an evaporator
515
, an entrance port
60
of a second passage
63
through which a gas-phase refrigerant returning from the evaporator travels, and an exit port
64
for sending out the refrigerant towards a compressor
511
.
The port
52
through which the liquid-phase refrigerant travels is communicated to a valve chamber
54
placed above a central axis of the valve body
50
, and the valve chamber
54
is sealed by a nut plug
130
. The valve chamber
54
is communicated through an orifice
78
to a port
58
for sending out the refrigerant to the evaporator
515
. A spherical valve member
120
is placed at the end of a narrow shaft
114
which penetrates the orifice
78
. The valve member
120
is supported by a supporting member
122
, and the supporting member
122
biases the valve member
120
towards the orifice
78
by a bias spring
124
. By moving the valve member
120
and varying the gap formed between the valve and the orifice
78
, the passage area of the refrigerant may be adjusted. The liquid-phase refrigerant expands while travelling through the orifice
78
, and flows through the first passage
62
and exits from the port
58
to be sent out to the evaporator. The gas-phase refrigerant returning from the evaporator is introduced from the port
60
, travels through the second passage
63
and exits from the port
64
to be sent out to the compressor.
The valve body
50
further includes a first hole
70
formed from the upper end of the body along the axis, and a power element
80
is fixed by a screw and the like to the first hole. The power element
80
comprises a housing
81
and
91
which constitute a temperature sensing unit, and a diaphragm
82
being sandwiched between and welded to the housing
81
and
91
. Further, an upper end of a temperature sensing/pressure transmitting member
100
acting as a valve drive member is fixed, together with a diaphragm support member
82
′, to the round hole formed to the center of the diaphragm
82
by welding the whole circumferential area thereof. The diaphragm support member
82
′ is supported by the housing
81
.
The housing
81
,
91
is separated by the diaphragm
82
, thereby defining an upper chamber
83
and a lower chamber
85
. A temperature-responsive working fluid is filled inside the upper chamber
83
and a hollow portion
84
. After filling the working fluid, the upper chamber is sealed by a short pipe
21
. Further, a plug body welded onto the housing
91
may be utilized instead of the short pipe
21
.
The temperature sensing/pressure transmitting member
100
is formed of a hollow pipe-like member exposed to the second passage
63
, and to the interior of which is stored an activated carbon
40
. The peak portion of the temperature sensing/pressure transmitting member
100
is communicated to the upper chamber
83
, and a pressure space
83
a
is defined by the upper chamber
83
and the hollow portion
84
of the temperature sensing/pressure transmitting member
100
. The pipe-like temperature sensing/pressure transmitting member
100
penetrates through a second hole
72
formed on the axis line of the valve body
50
, and is inserted to a third hole
74
. A gap exists between the second hole
72
and the temperature sensing/pressure transmitting member
100
, through which the refrigerant inside the passage
63
is introduced to the lower chamber
85
of the diaphragm.
The temperature sensing/pressure transmitting member
100
is inserted slidably to the third hole
74
, and the end portion of the member
100
is connected to one end of a

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