Expansion valve

Details Expansion valve Expansion valve

1998-10-28

2001-09-25

Tapolcai, William E. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000

Reexamination Certificate

active

06293472

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an expansion valve for controlling the flow rate of a refrigerant supplied to an evaporator in a refrigeration cycle of an air conditioning device, a refrigerating device and the like.
This type of expansion valve is used in a refrigeration cycle of an air conditioning device of a vehicle and the like, wherein
FIG. 15
is a vertical cross-sectional view of one example of an expansion valve widely used conventionally shown together with an outline of the refrigeration cycle, and
FIG. 16
shows the main portion thereof. The expansion valve
10
includes a roughly prismatic-shaped aluminum valve body
30
comprising a first passage
32
mounted in a refrigerant duct
11
of the refrigeration cycle from a refrigerant exit of a condenser
5
through a receiver
6
to a refrigerant entrance of an evaporator
8
through which a liquid-phase refrigerant travels, and a second passage
34
mounted in the refrigerant duct
11
from a refrigerant exit of the evaporator
8
to a refrigerant entrance of a compressor
4
through which a gas-phase refrigerant travels, said first passage
32
and said second passage
34
positioned above or below one another and separated by a separation wall
38
f.
On the first passage
32
is formed an orifice
32
a
for performing an adiabatic expansion of the liquid refrigerant being supplied from the refrigerant exit of the receiver
6
. A valve seat is formed on the entrance side of the orifice
32
a
or upper stream side of the first passage, and a valve
32
b
having a spherical shape supported by a valve member
32
c
from the upper stream side is positioned on said valve seat, wherein the valve
32
b
and the valve member
32
c
are fixed together by welding. The valve member
32
c
is positioned between the valve and a biasing means
32
d
of a compression spring and the like mounted on the lower portion of the valve body, and transmits the biasing force of the biasing means
32
d
to the valve
32
b
. The valve
32
b
is biased in the direction approaching the valve seat.
The first passage
32
to which the liquid refrigerant from the receiver
6
is introduced works as a passage for the liquid refrigerant, which comprises an entrance port
321
and a valve chamber
35
connected to the entrance port
321
. The valve chamber
35
is a chamber with a bottom formed coaxial to the orifice
32
a
, which is sealed by a plug
39
. The valve chamber
35
is communicated to the exit port
322
through the orifice
32
a
, and the exit port
322
is connected to the refrigerant entrance of the evaporator
8
.
Further, the valve body
30
includes a small radius hole
37
and a large radius hole
38
having a larger radius than the hole
37
formed coaxial to the orifice
32
a
and penetrating the second passage
34
, so as to provide a driving force to the valve
32
b
and to open or close the orifice
32
a
in correspondence to the exit temperature of the evaporator
8
. On the upper end of the valve body
30
is formed a screw hole
361
where a power element portion
36
working as a heat sensing portion is fixed.
The power element portion
36
is a member driven in correspondence to pressure, comprising a diaphragm
36
a
which is a metallic thin plate made of stainless steel with flexibility, an upper cover
36
d
and a lower cover
36
h
made of stainless steel mounted so as to contact each other with the diaphragm
36
a
positioned therebetween and working as sealing walls each defining a pressure chamber, an upper pressure chamber
36
d
and a lower pressure chamber
36
c
, having said diaphragm as one wall surface and divided into the upper and lower chambers by the diaphragm, and a blind plug
36
i
made of stainless steel for filling a predetermined refrigerant for sensing temperature and working as a diaphragm driving medium into said upper pressure chamber
36
b
, wherein said lower pressure chamber
36
c
is communicated to the second passage
34
through a pressure equalization hole
36
e
formed concentric to the center line of the orifice
32
a
. A refrigerant steam from the evaporator
8
flows through the second passage
34
, and the passage
34
works as a passage for the gas-phase refrigerant, the pressure of said gas-phase refrigerant being loaded to the lower pressure chamber
36
c
through the pressure equalization hole
36
e
. Further, a pipe-like mounting seat
362
is formed on the lower cover
36
h
, the mounting seat
362
being screwed onto the screw hole
361
, thereby being fixed to the valve body
30
.
The present body further includes a heat sensing shaft
36
f
made of aluminum, which contacts the diaphragm
36
a
inside the lower pressure chamber
36
c
and positioned so as to penetrate the second passage
34
and mounted slidably inside the large radius hole
38
in the separation hole
38
f
, thereby communicating the refrigerant exit temperature of the evaporator
8
to the lower pressure chamber
36
c
, and at the same time, provides drive force by being slided inside the large radius hole in correspondence to the displacement of the diaphragm
36
a
accompanied by the pressure difference between the upper pressure chamber
36
b
and the lower pressure chamber
36
c
. The body further includes an operation shaft
37
f
made of stainless steel positioned slidably inside the small radius hole
37
and having a smaller radius than the heat sensing shaft
36
f
for pressing the valve
32
b
against the bias force of the biasing means
32
d
in correspondence to the displacement of the heat sensing shaft
36
f
. The heat sensing shaft
36
f
is equipped with a sealing member for securing the sealing ability between the first passage
32
and the second passage
34
, such as an o-ring
36
g
. An upper end portion
36
k
of the heat sensing shaft
36
f
contacts the lower surface of the diaphragm
36
a
as a receiving portion, and comprises a stopper portion
36
L enlarged to the radial direction so as to gain a large contact area with the diaphragm. The displacement of the diaphragm
36
a
is transmitted to the valve
32
b
through the heat sensing shaft
36
f
, and the stopper portion
36
L is supported by the lower cover
36
h
so that the upper end portion
36
k
of the heat sensing shaft
36
f
may be slid inside the lower pressure chamber
36
c.
Moreover, the lower end of the heat sensing shaft
36
f
contacts the upper end of the operation shaft
37
f
at the bottom portion of the large radius hole
38
and the lower end of the operation shaft contacts the valve
32
b
. The heat sensing shaft
36
f
together with the operation shaft
37
f
form a heat sensing drive shaft, and this heat sensing drive shaft acts as a valve drive shaft for transmitting the displacement of the diaphragm
36
a
to the valve
32
b
, which comprises of an upper end portion and a heat conducting portion.
In the structure of the power element portion
36
, the heat sensing shaft
36
f
and the operation shaft
37
f
, when the operation shaft
37
f
is inserted to the small radius hole
37
and the heat sensing shaft
36
f
is inserted to the large radius hole
38
, the mounting seat
362
on the lower cover
36
h
is fixed by being connected to a screw hole
361
, the seal between the lower cover
36
h
and the valve body
30
being secured by the o-ring
36
m
. The screw hole
361
together with the lower cover
36
h
and the diaphragm
36
a
form the lower pressure chamber
36
c.
Accordingly, on the pressure equalization hole
36
e
, a valve drive shaft extended from the lower surface of the diaphragm
36
a
to the orifice
32
a
of the first passage
32
is concentrically positioned. Further, the portion
37
e
of the operation shaft
37
f
is formed smaller (narrower) than the inner radius of the orifice
32
a
so as to be inserted through the orifice
32
a
, and thereby, the refrigerant may pass through the orifice
32
a.
FIG.
16
(A) is a schematic view showing the structure of the power element portion
36
and the heat sensing shaft
36
f
in the expansion valve
10
ex

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