Thermal expansion valve

Details Thermal expansion valve Thermal expansion valve

2002-01-22

2003-05-13

Doerrler, William C. (Department: 3744)

Automatic temperature and humidity regulation

Thermostatic

With pressure control

C062S222000

Reexamination Certificate

active

06561433

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a thermal expansion valve equipped in a refrigeration system of an air conditioner for a vehicle and the like.
DESCRIPTION OF THE RELATED ART
FIG. 3
shows a conventional thermal expansion valve equipped in a refrigeration cycle of an air conditioner for a vehicle and the like. The conventional thermal expansion valve
100
comprises a valve body
1
including a high-pressure refrigerant passage
2
through which liquid-phase refrigerant to be decompressed travels, a low-pressure refrigerant passage
3
through which gas-phase refrigerant travels, and a valve hole
4
formed in the middle of the high-pressure refrigerant passage
2
; a valve means
5
that is driven to move toward and away from the valve hole
4
and thereby changing the opening of the valve hole; a pressure operation housing
10
equipped to the valve body
1
so as to sense the temperature of the gas-phase refrigerant, including a diaphragm
11
that drives the valve means
5
via an operating rod
6
so as to control the movement of the valve means, an airtight chamber
12
divided by the diaphragm and filled with a temperature sensitive gas, and a pressure equalizing chamber
13
being communicated with the low-pressure refrigerant passage
3
; and a plug
16
for sealing a hole
15
formed to the outer wall
14
of the pressure operation housing after the temperature sensitive gas is filled to the airtight chamber
12
, maintaining the gas-filled state.
In the drawing, reference
30
shows a compressor connected via a piping to the exit of the low-pressure refrigerant passage
3
, reference
31
is a condenser connected via a piping to the compressor
30
, reference
32
is a receiver tank connected via a piping to the condenser
31
and the entrance of the high-pressure refrigerant passage
2
, and reference
33
is an evaporator connected via a piping to the exit of the high-pressure refrigerant passage
2
and the entrance of the low-pressure refrigerant passage
3
.
A conventional method to seal the hole
15
on the outer wall with the plug
16
is disclosed in Japanese Patent Laid-Open Publication No. 6-185833 (185833/94). This prior-art welding method involves two welding steps, wherein the first welding step is a projection welding performed as a temporal welding with only temporal intensity, and the second welding step is performed by the solder-welding portion
19
that provides a lasting seal.
That is, as shown in
FIG. 4
showing the partial enlarged view of the plug
16
and the hole
15
on the housing outer wall
14
, the edge contact portion
19
a
between the spherical surface of the plug
16
and the circumferential portion of the housing outer wall
14
is projection-welded, thereby sealing the flange portion of the plug
16
by a solder weld
19
.
In another example of a conventional thermal expansion valve, the means for sealing a hole
15
on the outer wall of the housing with a plug
16
is disclosed in Japanese Patent Laid-Open Publication No. 8-226567 (226567/96). The structure of this thermal expansion valve is shown in FIG.
5
.
FIG. 5
shows a vertical cross-sectional view of the prior-art thermal expansion valve
100
. In the drawing, the thermal expansion valve
100
is equipped to a refrigeration cycle of an air conditioner for a vehicle and the like, wherein the valve body
1
of the thermal expansion valve
100
includes a high-pressure refrigerant passage
2
through which liquid-phase refrigerant to be decompressed travels, a low-pressure refrigerant passage
3
through which gas-phase refrigerant travels, and a valve hole
4
formed in the middle of the high-pressure refrigerant passage
2
comprising a small-diameter throttle hole. The liquid-phase refrigerant flowing from the receiver tank
32
to the high-pressure refrigerant passage
2
passes through the valve hole
4
having a small airflow area, where it experiences adiabatic expansion before flowing into the passage
2
′ for decompressed refrigerant.
The opening of the valve hole
4
where the refrigerant enters is formed as a valve seat, and at this valve seat is positioned a ball-shaped valve means
5
that can move toward and away from the valve seat, thereby changing the opening of the valve hole
4
. The valve means
5
is supported by a ball receiver
7
, and is biased toward closing the valve (toward being pressed against the valve seat of the valve hole
4
) by a compression coil spring
9
mounted between the ball receiver
7
and an adjusting nut
8
.
Reference number
10
shows a pressure operation housing that is arranged at the upper end of the valve body
1
for sensing the temperature of the gas-phase refrigerant, comprising a diaphragm
11
that drives the valve means
5
through the operating rod
6
, an airtight chamber
12
divided by the diaphragm and filled with temperature sensitive gas, and a pressure equalizing chamber
13
that communicates with the low-pressure refrigerant passage
3
.
A hole
15
is formed to the outer wall
14
of the housing
10
, and through this hole the temperature sensitive gas is filled into the airtight chamber
12
, and thereafter, the hole
15
on the outer wall is sealed using a metal plug
16
so as to maintain the gas-filled state.
Accordingly, the airtight chamber
12
senses the temperature of the gas-phase refrigerant traveling through the low-pressure refrigerant passage
3
, and the pressure within the airtight chamber
12
changes following the fluctuation of the temperature of the gas-phase refrigerant. On the other hand, the pressure equalizing chamber
13
positioned on the lower stream side of the diaphragm
11
is communicated, as mentioned above, with the low-pressure refrigerant passage
3
, so that the pressure of the chamber
13
equals the pressure of the gas-phase refrigerant traveling through the low-pressure refrigerant passage
3
. This structure enables the diaphragm
11
to be displaced according to the difference between the pressure within the airtight chamber
12
and the pressure within the pressure equalizing chamber
13
, and this movement is transmitted via the operating rod
6
to the valve means
5
that controls the opening of the valve hole
4
.
The plug
16
comprises a projection
16
a
that is inserted to the hole
15
of the housing outer wall
14
as shown in
FIG. 6
, and a cone-shaped portion
16
b
that contacts the circumference of the hole
15
of the housing outer wall
14
(the circumference forming a cross section that is sloped diagonally downward in a wide separated V-shape with a taper angle of 120 degrees toward the center of the hole
15
) with the tapered surface thereof having a taper angle of 90 to 120 degrees. The tapered contact surfaces of the cone-shaped portion
16
b
and the circumference of the hole formed to the outer wall
14
is projection welded with a length ranging from 0.2 mm to 1.5 mm, thereby forming a weld portion
17
, so that the hole
15
on the outer wall is sealed only by a projection weld maintaining the state where the chamber is completely filled with gas.
According to the prior art thermal expansion valve, if water (caused for example by dew condensation) adheres to the periphery of the plug, the weld portion may be corroded, and when corrosion occurs, air may leak through the welded portion. In other words, for example in the thermal expansion valve shown in
FIG. 5
, the periphery of the hole on the housing outer wall
14
and the plug
16
come into contact at their tapered surfaces and are attached together by projection weld as shown in
FIG. 6
, but since a recessed portion
18
exists around the projection weld portion
17
, if water gathers around the recess
18
, the weld is corroded and the airtight state can be damaged at the weld portion.
In order to solve this problem, in a conventional thermal expansion valve, a corrosion inhibitor (such as an adhesive) is injected to the recessed portion, as shown in FIG.
7
.
FIG. 7
is an enlarged vertical cross-sectional view showing the structure of the plug
16

Affiliated with

Also associated with

Rating

Thermal expansion valve does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Thermal expansion valve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal expansion valve will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3016675