Automatic temperature and humidity regulation – Thermostatic – With pressure control
Reexamination Certificate
2000-04-14
2001-05-01
Tapolcai, William E. (Department: 3753)
Automatic temperature and humidity regulation
Thermostatic
With pressure control
C062S225000, C236S09900R
Reexamination Certificate
active
06223994
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermal expansion valve used for a refrigerant cycle.
CONVENTIONAL ART
Conventionally, for the purpose of controlling a flow amount of a refrigerant supplied to an evaporator in a refrigerant cycle and decreasing a pressure of the refrigerant, a thermal expansion valve shown in
FIG. 2
has been used.
In
FIG. 2
, a first refrigerant passage
514
on which an orifice
516
is formed and a second refrigerant passage
519
are provided in a rectangular cylindrical valve body
510
in a mutually independent manner. An end of the first refrigerant passage
514
is communicated with an inlet port of an evaporator
515
, and an outlet port of the evaporator
515
is connected to another end of the first refrigerant passage
514
via the second refrigerant passage
519
, a compressor
511
, a condenser
512
and a receiver
513
. Urging means
517
corresponding to a bias spring for urging a spherical valve member
518
engaged with and disengaged from the orifice
516
is provided in a valve chamber
514
communicating with the first refrigerant passage
514
. In this case, the valve caliber
524
is sealed by a plug
525
and the valve member
518
is urged via a supporting portion
526
. A power element
520
disposed adjacent to the second refrigerant passage
519
and having a diaphragm
522
is fixed to the valve body
510
. An upper chamber
520
a
of the power element
520
partitioned by the diaphragm
522
is made air-tight, condition, and a temperature corresponding working fluid is charged therein.
A small pipe
521
extending from the upper chamber
520
a
of the power element
520
is sealed at an end portion thereof after being used for discharging an air from the upper chamber
520
a
and pouring a temperature corresponding working fluid into the upper chamber
520
a
. An extending end of a valve driving member
523
corresponding to a temperature sensing and pressure transmitting member extending through the second refrigerant passage
519
from the valve member
518
within the valve body
510
is arranged in a lower chamber
520
b
of the power element
520
and is brought into contact with the diaphragm
522
. A valve driving member
523
is made of a material having a large heat capacity and transmits a temperature of a refrigerant vapor flowing through the second refrigerant passage
519
and discharged from the outlet port of the evaporator
515
to a temperature corresponding working fluid in the upper chamber
520
a
of the power element
520
so as to generate a working gas having a pressure corresponding to the temperature. The lower chamber
520
b
is communicated with the second refrigerant passage
519
via a gap in the periphery of the valve driving member
523
within the valve body
510
.
Accordingly, the diaphragm
522
of the power element
520
adjusts a valve opening degree (that is, a flowing amount of a liquid refrigerant to the inlet port of the evaporator) of the valve member
518
with respect to the orifice
516
by means of the valve driving member
523
under an influence of an urging force of the urging means
517
for the valve member
518
in accordance with a difference between a pressure of the working gas in a temperature corresponding working fluid within the upper chamber
520
a
and a pressure of the refrigerant vapor in the outlet port of the evaporator
515
within the lower chamber
520
b.
In the conventional thermal expansion valve mentioned above, the power element
520
is exposed to an external atmosphere, and a temperature corresponding working fluid within the upper chamber
520
a
is influenced not only by the temperature of the refrigerant disposed in the outlet port of the evaporator and transmitted by the valve driving member
523
but also by the external atmosphere, particularly, a temperature in an engine room. Further, there is readily generated a so-called hunting phenomenon in which opening and closing operations of the valve member
518
are frequently repeated due to an excessively sensitive response to the temperature of the refrigerant in the outlet port of the evaporator. This hunting is caused by a structure of the evaporator, a method of piping the refrigerant cycle, a method of using the thermal expansion valve, a balance to a thermal load and the like.
A heat ballast member has been conventionally employed as means for preventing the hunting phenomenon.
FIG. 3
is a cross sectional view of a thermal expansion valve which uses the heat ballast member. The thermal expansion valve in
FIG. 3
is widely different from the conventional thermal expansion valve in
FIG. 2
in structures of the diaphragm and of the valve driving member corresponding to the temperature sensing and pressure transmitting member, and other structures are the same. In
FIG. 3
, the thermal expansion valve has a rectangular cylindrical valve body
50
, and the valve body
50
is provided with a port
52
through which a liquid phase refrigerant flowing from the receiver tank
513
via the condenser
512
is introduced to a first passage
62
, a port
58
which feeds out the refrigerant from the first passage
62
to the evaporator
515
, an inlet port
60
of a second port
63
through which a gas phase refrigerant returning from the evaporator passes, and an outlet port
64
which feeds out the refrigerant to a side of the compressor
511
.
The port
52
through which the liquid phase refrigerant is introduced is communicated with a valve chamber
54
provided on a center axis of the valve body
50
and the valve chamber
54
is sealed by a nut-shaped plug
130
. The valve chamber
54
is communicated with the port
58
for feeding out the refrigerant to the evaporator
515
via an orifice
78
. A spherical valve member
120
is placed at a distal end of a shaft
114
having a small diameter and extending through the orifice
78
, the valve member
120
is supported by a supporting member
122
, and the supporting member
122
urges the valve member
120
toward the orifice
78
by means of a bias spring
124
. A flow passage area of the refrigerant can be adjusted by changing an interval formed between the valve member
120
and the orifice
78
. The liquid phase refrigerant expands while passing through the orifice
78
and is fed out to the evaporator side from the port
58
through the first passage
62
. The gas phase refrigerant returning from the evaporator is introduced from the port
60
and is fed out to the compressor side from the port
64
through the second passage
63
.
The valve body
50
has a first hole
70
formed on an axis from an upper end portion thereof, and a power element portion
80
is mounted to the first hole by utilizing a screw portion or the like. The power element portion
80
has housings
81
and
91
constituting a temperature sensing portion and a diaphragm
82
gripped between the housings and adhered to the housing by means of a welding, and an upper end portion of a temperature sensing and pressure transmitting member
100
is mounted to a circular hole in a center portion of the diaphragm
82
together with a diaphragm supporting member
82
′ by welding all the periphery. In this case, the diaphragm supporting member
82
′ is supported by housing
81
.
A refrigerant comprising gas and liquid phases which is the same as or similar to the refrigerant flowing within the passage
62
is charged within the housings
81
and
91
as a temperature corresponding working fluid, and is sealed by a small pipe
21
after being charged. In this case, in place of the small pipe
21
, a plug body welded to the housing
91
may be used. Inner portions of the housings
81
and
91
are partitioned by the diaphragm
82
, so that an upper chamber
83
and a lower chamber
85
are formed.
The temperature sensing and pressure transmitting member
100
is constituted by a hollow pipe member exposed within the second passage
63
, and a heat ballast member
40
is received within the temperature sensing and pressure transmitting member
100
.
Fukuda Eiji
Watanabe Kazuhiko
Coleman Henry D.
Fujikoki Corporation
Sapone William J.
Sudol R. Neil
Tapolcai William E.
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