Thermal expansion valve

Details Thermal expansion valve Thermal expansion valve

2000-11-07

2002-03-12

Doerrler, William (Department: 3754)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S225000

Reexamination Certificate

active

06354509

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a thermal expansion valve used in a refrigeration cycle.
DESCRIPTION OF THE RELATED ART
Generally, of the components forming the refrigeration cycle in an air conditioner for vehicles, the evaporator is placed inside the passenger room, and others such as the compressor and the like are placed inside the engine room. The refrigeration cycle is provided with a thermal expansion valve for controlling the amount of refrigerant entering the evaporator.
FIG. 26
is a vertical cross-sectional view showing the state where a box-type expansion valve conventionally used as an expansion valve is placed in the refrigeration cycle of the air conditioner used for a vehicle, and
FIG. 27
is a schematic perspective view of the same. In
FIG. 26
, an expansion valve
10
is formed of a prismatic valve body
30
made from aluminum and the like, a first passage
32
through which refrigerant travels from a condenser
5
via a receiver
6
to an evaporator
8
in a refrigeration cycle
11
, and a second passage
34
through which refrigerant travels from the evaporator
8
to a compressor
4
, both passages being formed on the valve body
30
and placed vertically apart from each other. Also, the expansion valve
10
includes an orifice
32
a
and a valve chamber
35
provided to the first passage
32
, a spherical valve means
32
b
provided to the upstream side of the passage
32
for controlling the amount of refrigerant traveling through the orifice
32
a
, and an adjust screw
39
for a spring
32
d
providing pressure to the valve means
32
b
in the direction toward the orifice
32
a
through a valve member
32
c
. The adjust screw
39
having a screw portion
39
f
is screwed retrievably to a mount hole
30
a
connecting to the valve chamber
35
of the first passage
32
from the lower end surface of the valve body
30
, and an O-ring
39
g
is mounted to the adjust screw
39
so as to secure airtightness of the valve body
30
. The opening of the valve means
32
d
to the orifice
32
a
is adjusted by the adjust screw
39
and the pressure spring
32
d.
Reference number
321
is an entrance port where refrigerant exiting the receiver
6
and traveling toward the evaporator
8
enters. The entrance port
321
is connected to the valve chamber
35
, and reference number
322
is an exit port of the refrigerant flowing into the evaporator
8
. Also, reference number
50
of
FIG. 27
shows bolt holes for mounting the expansion valve, and the lower portion of the valve body
30
is thinned. A small-diameter aperture
37
for opening and closing the orifice
32
a
by providing driving force to the valve means
32
b
corresponding to the exit temperature of the evaporator
8
, and an aperture
38
having a larger diameter than the aperture
37
are provided to the valve body
30
coaxial to the orifice
32
a
. A screw hole
361
for fixing the power element portion
36
as a heat sensing portion is provided to the upper end of the valve body
30
.
The power element portion
36
constitutes a diaphragm
36
a
made of stainless steel and the like, and an upper pressure working chamber
36
b
and a lower pressure working chamber
36
c
formed coherent to each other by welding while interposing the diaphragm
36
a
, forming two airtight heat sensing chambers above and below the diaphragm
36
a
. The power element portion
36
is equipped with an upper lid
36
d
and a lower lid
36
h
made of stainless steel and the like, and a plug body
36
k
for enclosing predetermined refrigerant acting as a diaphragm driving fluid to the upper pressure working chamber
36
b
, and the lower lid
36
h
is screwed into a screw hole
361
through a packing
40
. The lower pressure working chamber
36
c
is connected to the second passage
34
through an equalizing hole
36
e
formed concentric with the center line of the orifice
32
a
. Refrigerant from the evaporator
8
travels through the second passage
34
, and the passage
34
becomes the passage for vapor refrigerant, and the pressure of the refrigerant is loaded to the lower pressure working chamber
36
c
through the pressure equalizing hole
36
e
. Reference number
342
is an entrance port where refrigerant exiting the evaporator
8
enters, and
341
is an exit port where refrigerant discharged to the compressor
4
exits.
Also, a peak portion
312
formed in a large-diameter saucer which comes into contact with the central portion of the lower surface of the diaphragm
36
a
is provided inside the lower pressure working chamber
36
c
. The power element portion
36
is further comprised of a heat sensing shaft
36
f
made of aluminum which pierces through the second passage
34
and is arranged slidably inside the large-diameter aperture
38
to transmit the temperature at the refrigerant exit of the evaporator
8
to the lower pressure working chamber
36
c
and which provides driving force by sliding inside the large-diameter aperture
38
corresponding to the displacement of the diaphragm
36
a
based on the difference in pressure between the upper pressure working chamber
36
b
and the lower pressure working chamber
36
c
, and a working shaft
37
f
made of stainless steel and having a smaller diameter than the heat sensing shaft
36
f
which is arranged slidably inside the small-diameter aperture
37
to provide pressure to the valve means
32
b
resisting to the elastic force of the spring means
32
d
corresponding to the displacement of the heat sensing shaft
36
f
. The upper end portion of the heat sensing shaft
36
f
is composed from a peak portion
312
as a receiving portion of the diaphragm
36
a
and a large-diameter portion
314
sliding inside the lower pressure working chamber
36
c
, and the lower end portion of the heat sensing shaft
36
f
comes into contact with the upper end portion of the working shaft
37
f
, the lower end portion of the working shaft
37
f
comes into contact with the valve means
32
b
, so that the heat sensing shaft
36
f
and the working shaft
37
f
constitute altogether the valve means driving shaft
318
. The peak portion
312
and the large-diameter portion
314
may be formed as one member.
That is, the valve means driving shaft
318
extending from the lower surface of the diaphragm
36
a
to the orifice
32
a
of the first passage
32
is concentrically arranged in the equalizing hole
36
e
. The portion
37
e
of the working shaft
37
f
having in a diameter smaller than the inner diameter of the orifice
32
a
pierces through the orifice
32
a
, and the refrigerant passes inside the orifice
32
a
. Also, an O-ring
36
g
is provided to the heat sensing shaft
36
f
in order to secure airtightness of the first passage
32
and the second passage
34
.
A known diaphragm driving fluid is filled inside the upper pressure working chamber
36
b
of the pressure working housing
36
d
, and the heat of the refrigerant at the refrigerant exit of the evaporator
8
traveling inside the second passage
34
is transmitted to the diaphragm driving fluid through the diaphragm
36
a
and the valve means driving shaft
318
exposed to the second passage
34
or the equalizing hole
36
e
connected to the second passage
34
.
The diaphragm driving liquid inside the upper pressure working chamber
36
b
turns into gas corresponding to the above-mentioned transmitted heat, and loads pressure to the upper surface of the diaphragm
36
a
. The diaphragm
36
a
is displaced vertically by the difference in the above-mentioned pressure of the diaphragm driving gas loaded to the upper surface and the pressure loaded to the lower side of the diaphragm
36
a.
The vertical displacement of the central portion of the diaphragm
36
a
is transmitted to the valve means
32
b
through the valve means driving shaft, and moves the valve means
32
b
closer to or away from the valve seat of the orifice
32
a
. As a result, the flow rate of the refrigerant is controlled.
Namely, the temperature of the low-pressure vapor refrigerant at the exit side of the evaporator
8
, that

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