Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2001-11-30
2002-10-08
Capossela, Ronald (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
C251S129110
Reexamination Certificate
active
06460349
ABSTRACT:
BACKGROUND OF THE INVENTION
This application is based on and claims priority under 35 U.S.C. § 119 with respect to Japanese Application No. 2000-364341, filed on Nov. 30, 2000, and Japanese Application No. 2001-226610 filed on Jul. 26, 2001, the entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
This invention generally relates to a pressure switching mechanism for the operation gas of a pulse tube refrigerator used for cryogenic refrigeration and a pulse tube refrigerator having the same. More particularly, the present invention pertains to a rotary valve unit for achieving high performance cryogenic effects and a pulse tube refrigerator applied therewith.
DESCRIPTION OF THE BACKGROUND
A known pulse tube refrigerator is disclosed in
Cryogenics
, Vol. 30 September Supplement (1990), p.262.
FIG. 13
shows the structure of the foregoing known pulse tube refrigerator. A pulse tube refrigerator
611
includes a cold head
303
, a regenerator
301
has a regenerator port
311
on one end and is in communication with the cold head
303
on the other end, a pulse tube
302
has a pulse tube port
312
on one end and is in communication with the cold head
303
on the other end. A first solenoid valve
701
and a second solenoid valve
702
are positioned in parallel to each other and are connected to the regenerator port
311
of the regenerator
301
via a regenerator line
321
. A third solenoid valve
703
is connected to the pulse tube port
312
of the pulse tube
302
via a pulse tube line
322
. A compressor unit
100
has an outlet port
111
and an inlet port
112
, in which the outlet port
111
is connected to the first solenoid valve
701
via a high pressure line
121
and the inlet port
112
is connected to the second solenoid valve
702
via a low pressure line
122
. A reservoir
401
having a reservoir port
411
is connected to the third solenoid valve
703
via a reservoir line
421
. The pressure of the outlet port
111
of the compressor unit
100
corresponds to a high pressure PH, the pressure of the inlet port
112
of the compressor unit
100
corresponds to a low pressure PL, and the pressure in the reservoir
401
corresponds to a middle pressure PM. The high pressure PH is determined to be higher than the middle pressure PM and the middle pressure PM is determined to be higher than the low pressure PL.
The operation of the foregoing pulse tube refrigerator
611
will be explained as follows. First, when the first solenoid valve
701
and the second solenoid valve
702
are closed and the pressure in the pulse tube
302
and the regenerator
301
correspond to the low pressure PL of the inlet port
112
, the third solenoid valve
703
is opened. The gas in the reservoir
401
is supplied to the pulse tube port
312
of the pulse tube
302
, and thus to increase the pressure of the pulse tube
302
and the regenerator
301
from the low pressure PL to the middle pressure PM corresponding to the pressure in the reservoir
401
. Then, the third solenoid valve
703
is closed.
Second, the first solenoid valve
701
is opened. The high pressure gas with the high pressure PH which is compressed and the heat of which is radiated in the compressor unit
100
is cooled down in the regenerator
301
and supplied to the cold head
303
side of the pulse tube
302
to increase the pressure of the regenerator
301
and the pulse tube
302
from the middle pressure PM corresponding to the pressure of the reservoir
401
to the high pressure PH corresponding to the pressure of the outlet port
111
. Then the first solenoid valve
701
is closed.
Third, the third solenoid valve
703
is opened. The gas in the pulse tube port
312
side of the pulse tube
302
is returned to the reservoir
401
to decrease the pressure of the pulse tube
302
and the regenerator
301
from the high pressure PH to the middle pressure PM corresponding to the pressure of the reservoir
401
. In this case, the gas temperature in the cold head
303
side of the pulse tube
302
becomes lower than the temperature of the cold head
303
due to the adiabatic expansion. Then, the third solenoid valve
703
is closed.
Finally, the second solenoid valve
702
is opened. The gas is returned to the compressor unit
100
to decrease the pressure of the regenerator
301
and the pulse tube
302
from the middle pressure PM to the low pressure PL corresponding to the pressure of the inlet port
112
. In this case, the gas temperature in the cold head
303
side of the pulse tube
302
becomes lower due to adiabatic expansion. The gas with lowered temperature is returned to the compressor unit
100
while cooling down the cold head
303
and the regenerator
301
. Then, the second solenoid valve
702
is closed.
The foregoing process is determined as one cycle. By repeating this cycle with a frequency of one to several Hz, a cryogenic temperature is generated at the cold head
303
.
According to the pulse tube refrigerator
611
, since the pressure in the regenerator
301
and the pulse tube
302
has been increased from the low pressure PL to the middle pressure PM corresponding to the pressure in the reservoir
401
before the first solenoid valve
701
is opened, the loss caused by the differential pressure generated when the high pressure gas with high pressure PH is supplied from the outlet port
111
of the compressor unit
100
to the regenerator
301
and the pulse tube
302
after the first solenoid valve
701
is opened is reduced.
In addition, since the pressure of the regenerator
301
and the pulse tube
302
is decreased from the high pressure PH to the middle pressure PM corresponding to the pressure of the reservoir
401
before opening the second solenoid valve
702
, the loss caused due to the differential pressure generated when the gas of the regenerator
301
and the pulse tube
303
is supplied to the inlet port
112
with the low pressure PL corresponding to the pressure of the compressor unit
100
when opening the second solenoid valve
702
is reduced.
Another known pulse tube refrigerator is shown in
FIG. 14. A
pulse tube refrigerator
612
includes a cold head
303
. A regenerator
301
has a regenerator port
311
on one end and is in communication with the cold head
303
on the other end. A pulse tube
302
has a pulse tube port
312
on one end and is in communication with the cold head
303
on the other end. A first solenoid valve
701
and a second solenoid valve
702
are positioned in parallel each other and are connected to the regenerator port
311
of the regenerator
301
via a regenerator line
321
. A third solenoid valve
703
and a fourth solenoid valve
704
are positioned in parallel and are connected to the pulse tube port
312
of the pulse tube
302
via a pulse tube line
322
. A compressor unit
100
has an outlet port
111
and an inlet port
112
in which the outlet port
11
is connected to the first solenoid valve
701
via a high pressure line
121
and the inlet port
112
is connected to the second solenoid valve
702
via a low pressure line
122
. A reservoir
401
has a reservoir port
411
which is connected to the third solenoid valve
703
via a reservoir line
421
, and an auxiliary reservoir
402
has an auxiliary reservoir port
412
, and the auxiliary reservoir port
412
is connected to the fourth solenoid valve
704
via an auxiliary reservoir line
422
. The pressure of the outlet port
111
of the compressor unit
100
corresponds to a high pressure PH, the pressure of the inlet port
112
of the compressor unit
100
corresponds to a low pressure PL, the pressure in the reservoir
401
corresponds to a first middle pressure PM
1
, and the pressure in the auxiliary reservoir
402
corresponds to a second middle pressure PM
2
. The high pressure PH is determined to be higher than the second middle pressure PM
2
, the second middle pressure PM
2
is determined to be higher than the first middle pressure PM
1
and the first middle pressure PM
1
is determined to be higher than the low pressure PL (
Inoue Tatsuo
Katsuragawa Shinji
Kawano Shin
Nogawa Masahumi
Aisin Seiki Kabushiki Kaisha
Capossela Ronald
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