Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2002-02-27
2004-06-08
Yu, Justine R. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S053000
Reexamination Certificate
active
06746214
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to control valves for controlling displacement of variable displacement compressors used in, for example, automobile air conditioners, and, more particularly, to improvement of pressure sensitive portions that detect suction pressure of compressors.
Japanese Laid-Open Patent Publication No. 9-268973 discloses a conventional control valve
1
for a variable displacement compressor. The control valve
1
is located in a refrigerant gas passage that connects a discharge pressure zone to a crank chamber of the compressor. The control valve
1
adjusts the pressure in the crank chamber to vary the displacement of the compressor. With reference to
FIG. 8
, the control valve
1
includes a body
21
, which accommodates a valve body
23
, and a pressure sensitive portion
10
, which is connected to the body
21
. The pressure sensitive portion
10
includes a case
13
and a pressure sensitive member, or a metal bellows
11
, which is accommodated in the case
13
. The bellows
11
is soldered to an upper dolly block
15
a
and a lower dolly block
15
b
, which oppose each other. A pressure sensitive chamber is formed in the bellows
11
. The bellows
11
moves in accordance with suction pressure Ps of the compressor and senses the suction pressure Ps. The lower dolly block
15
b
is joined with a transmitting rod
22
. The lower dolly block
15
b
and the transmitting rod
22
transmit the movement of the bellows
11
to the valve body
23
.
An adjuster
18
is fitted to an upper opening of the case
13
. The adjuster
18
adjusts the urging force of the bellows
11
. More specifically, the interval between the upper dolly block
15
a
and the lower dolly block
15
b
, or the longitudinal dimension of the bellows
11
, is changed depending on the position of the adjuster
18
. The change in the longitudinal dimension, or spring load, of the bellows
11
affects the characteristics (the valve opening pressure) of the control valve
1
. The conventional control valve
1
regulates the characteristics of the control valve
1
by adjusting the position of the adjuster
18
.
Since the machining cost of the bellows
11
is relatively high, the bellows
11
makes it difficult to lower the manufacturing cost of the control valve
1
.
To enable the control valve
1
to operate stably, it is preferred that the pressure sensitive chamber be maintained substantially as vacuum. However, since the bellows
11
is soldered to the upper dolly block
15
a
and the lower dolly block
15
b
, a volatile substance generated by the soldering, such as flux, may enter the pressure sensitive chamber. This decreases the vacuum level of the pressure sensitive chamber. Further, air bubbles or cavities formed in the solder may cause a slow leak, thus changing the vacuum level of the pressure sensitive chamber. If the pressure in the pressure sensitive chamber is changed, the accuracy of the control valve
1
is lowered. Instead of the soldering, the bellows
11
may be connected to the upper dolly block
15
a
and the lower dolly block
15
b
using lazar. However, since the cost for lazar welding equipment is relatively high, the manufacturing cost of the control valve
1
is increased, which is problematic.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide a highly accurate and relatively inexpensive control valve.
To achieve the above objective, an embodiment of the present invention provides a control valve of a variable displacement compressor, which includes a suction passage in which refrigerant gas at a relatively low pressure flows, a discharge pressure zone in which the refrigerant gas compressed at a relatively high pressure flows, a crank chamber that accommodates a cam, and a supply passage that connects the discharge pressure zone to the crank chamber. The control valve includes a body, which accommodates a valve body that opens or closes a valve hole connected to the supply passage, and a pressure sensitive portion, which is fixed to the body for detecting the pressure in the suction passage. The pressure sensitive portion includes a diaphragm, which is moved in relation to the pressure in the suction passage, a first case, which has a first flange and cooperates with the diaphragm to define a pressure sensitive chamber, and a second case, which has a second flange that cooperates with the first flange to hold the diaphragm.
Another embodiment provides a control valve of a variable displacement compressor, which includes a suction passage in which refrigerant gas at a relatively low pressure flows, a discharge pressure zone in which the refrigerant gas compressed at a relatively high pressure flows, a crank chamber that accommodates a cam, and a supply passage that connects the discharge pressure zone to the crank chamber. The control valve includes a pressure sensitive portion, which detects the pressure in the suction passage. The pressure sensitive portion includes a diaphragm, which is moved in relation to the pressure in the suction passage, a first case, which has a first flange and cooperates with the diaphragm to define a pressure sensitive chamber, and a second case, which has a second flange that cooperates with the first flange to hold the diaphragm. The control valve further includes a body, which accommodates a valve body for opening or closing a valve hole connected to the supply passage, and a positioning surface, which is formed in the body for positioning the diaphragm by contacting the second case.
Another embodiment of the present invention provides a method for manufacturing a control valve of a variable displacement compressor. The control valve includes a body, which accommodates a valve body that changes the opening size of a valve hole, and a pressure sensitive portion, which is attached to the body for detecting the pressure in the compressor. The method includes the steps of forming a positioning surface in the body at a position corresponding to a predetermined interval from the valve hole, accommodating a pressure sensitive spring and a pair of dolly blocks, which holds opposite ends of the pressure sensitive spring, in a first case that has a first flange, accommodating a connecting member in a second case that has a second flange, fixing the first case and the second case by clamping a diaphragm between the first flange and the second flange, setting the pressure in a pressure sensitive chamber, which is defined by the diaphragm and the first case, to a predetermined value, and attaching the pressure sensitive portion to the body by enabling the second case to contact the positioning surface of the body.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 5145326 (1992-09-01), Kimura et al.
patent: 5762476 (1998-06-01), Ota et al.
patent: 6164925 (2000-12-01), Yokomachi et al.
patent: 6192699 (2001-02-01), Kato et al.
patent: 6213727 (2001-04-01), Kawaguchi
patent: 6302656 (2001-10-01), Hirota
patent: 6334759 (2002-01-01), Kaneko et al.
patent: 06-173852 (1994-06-01), None
patent: 9-268973 (1997-10-01), None
patent: 2000-249051 (2000-09-01), None
Ichikawa Takaaki
Okada Satoru
Sakai Takayuki
Liu Han L
Pacific Industrial Co. Ltd.
Patterson Thuente Skaar & Christensen P.A.
Yu Justine R.
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