Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
1999-10-28
2001-08-28
Capossela, Ronald (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
C060S520000
Reexamination Certificate
active
06279324
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a heat-regenerating type cryogenic cooling apparatus including a heat regenerator whose interior is packed with a regenerating material, and in particular to an improvement in a pressure vibration device employed in such a heat-regenerating type cryogenic cooling apparatus.
2. Discussion of the Background
FIG. 6
illustrates a conventional heat-regenerating type cryogenic cooling apparatus
104
. This apparatus
104
includes a cryogenic temperature generating device
10
and a pressure vibration generating device
20
. The cryogenic temperature generating device
10
is constructed by a series connection of a heat regenerator
11
, a cold head
12
, and an expanding device
13
which are arranged in such an order. The pressure vibration device
20
which establishes a pressure vibration in a working fluid is the cryogenic temperature generating device
10
.
The pressure vibration generating device
20
includes a compressor
21
having a discharging port
21
a
and a sucking port
21
b
, a high-pressure line
22
whose one end is in fluid communication with the discharging port
21
a
of the compressor
21
, a low-pressure line
23
whose one end is in fluid communication with the sucking port
21
b
of the compressor
21
, a high-pressure open/close valve
24
connected to the other end of the high-pressure line
22
, a low-pressure open/close valve
25
connected to the other end of the low-pressure line
23
, a high-pressure side line
26
connecting the high-pressure open/close valve
24
and the heat regenerator
11
, and a low-pressure side line
27
connecting the low-pressure open/close valve
25
and the heat regenerator
11
.
As the expanding device
13
, there is a piston or other similar element which causes a volume change of working space, in the case of a Gifford-McMahon type cryo-cooler or a Solvay cryo-cooler. In case of a Gifford-McMahon type pulse tube refrigerator, the expanding device
3
is in the form of a pulse tube having therein a hollow volume space.
In the foregoing heat-regenerating type cryogenic cooling apparatus
104
, a cyclic pressure vibration is caused by open-close cycling of the valves
24
and
25
, and is introduced into a working space which is defined mainly between the heat regenerator
11
and the expanding device
13
, in which the cold head
12
is positioned. This causes reciprocal movement of the working gas in the working space, thereby generating a cryogenic temperature at the expanding device
13
which is obtained by way of the cold head
12
.
However, while the apparatus
104
is in operation, in the course of the working gas flow into the working space in the cryogenic temperature generating device
10
from the line
22
by opening the valve
24
, it is found that the pressure in the line
22
fails to keep the designed value and becomes smaller by a slight value, while if the valve
24
is closed the pressure in the line
22
increases beyond the designed value. Similarly, while the apparatus is in operation, in the course of the working gas flow from the working space in the cryogenic temperature generating device
10
into the line
23
by opening the valve
25
, it is found that the pressure in the line
23
fails to keep the designed value and becomes larger by a slight value, while if the valve
25
is closed the pressure in the line
23
increases beyond the designed value. Such a pressure decrease in the line
22
and a pressure increase in the line
23
affects the behavior of the working gas in the working space, which lowers the cooling efficiency.
In detail, immediately upon simultaneous closure of the valve
25
and opening of the valve
24
, the pressure in the line
22
falls, which causes the pressure in the working space to gradually approach the designed value, and in the worst case to fail to reach this value. Similarly, immediately upon simultaneous closure of the valve
24
and opening of the valve
25
, the pressure in the line
23
increases, which causes a pressure in the working space to gradually approach the designed value and in the worst case to fail to reach this value. Such gradual changes in approaching the designed values reduce the PV-work or the virtual PV-work. In addition, a ripple of working gas occurs in the line
22
(
23
) every time that a cycle of operations of the valve
24
(
25
) terminates, which also lowers the cooling efficiency.
SUMMARY OF THE INVENTION
It is, therefore, a principal object of the present invention to provide a heat-generating type cryogenic cooling apparatus which is free from the foregoing drawbacks.
Another object of the present invention is to improve a pressure vibration device of a heat-generating type cryogenic cooling apparatus wherein a deviation of the pressure in each of the high-pressure and the low-pressure lines from the designed reference value is kept as small as possible, to prevent lowering the efficiency of the cryogenic cooling apparatus.
The invention is based upon the novel recognition that when lowering the pressure in the high-pressure line while the working gas is being supplied from the pressure vibration device to the working space of the cryogenic temperature generating device by way of the opening of the high-pressure open/close valve, the discharged amount of the working gas from the high-pressure line toward the cryogenic temperature generating device becomes greater than the discharged amount of the working gas from the compressor to the high-pressure line, which results in an expansion of the working gas in the high-pressure line to cause an instantaneous pressure drop therein.
In view of this phenomenon, the heat-regenerating type cryogenic cooling apparatus according to the present invention comprises a cryogenic temperature generating part including a heat regenerator; and a pressure vibrating part connected to the cryogenic temperature generating part and establishing pressure vibration of a working gas therein, the pressure vibrating part including a compressor having a sucking port and a discharging port, a high-pressure line whose one end is connected to the discharge port of the compressor, a low pressure line whose one end is connected to the sucking port of the compressor, a high-pressure open/close valve connected to the other end of the high-pressure line, a low-pressure open/close valve connected to the other end of the low-pressure line, a high-pressure side passage connecting the high-pressure open/close valve and the cryogenic temperature generating part, a low-pressure side passage connecting the low-pressure open/close valve and the cryogenic temperature generating part, and a high-pressure source in fluid communication with the high-pressure line.
REFERENCES:
patent: 5345770 (1994-09-01), Inaguchi
patent: 5417071 (1995-05-01), Inaguchi
patent: 5471841 (1995-12-01), Inaguchi
patent: 5701742 (1997-12-01), Eckels et al.
Inoue Tatsuo
Kawano Shin
Nogawa Masafumi
Zhu Shaowei
Aisin Seiki Kabushiki Kaisha
Capossela Ronald
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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