Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2000-03-30
2001-10-16
Doerrler, William (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
Reexamination Certificate
active
06301902
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pulse tube refrigerator, and more particularly to a structure of a four valve type pulse tube refrigerator.
2. Discussion of the Background
A conventional four valve type pulse tube refrigerator is shown in FIG.
11
. In the drawing, a four valve type pulse tube refrigerator
201
includes a compressor
1
, a first high pressure on-off valve
4
connected with an outlet port
1
a
through a first level high pressure passage
2
, a first low pressure on-off valve
5
connected with an inlet port
1
b
through a first level low pressure passage
3
, a regenerator
8
having a low temperature end
8
a
and a high temperature end
8
b
, the regenerator being connected with the first high pressure on-off valve
4
through a regenerator side high pressure passage
6
at the high temperature end
8
b
of the regenerator
8
and being connected with the first low pressure on-off valve
5
through a regenerator side low pressure passage
7
, cold head
9
connected with the low temperature end
8
a
of the regenerator
8
, a pulse tube
10
having a low temperature end
10
a
and high temperature end
10
b
and connected with the cold head
9
at the low temperature end
10
b
thereof, a second high pressure on-off valve
11
connected with a radiator
15
attached to the high temperature end
10
b
through a pulse tube side high pressure passage
16
, a second low pressure on-off valve
12
connected with the radiator
15
through a pulse tube side low pressure passage
17
, a second level high pressure passage
13
connected with the first level high pressure passage
2
at one end and connected with the second high pressure on-off valve
11
at the other end, and a second level low pressure passage
14
connected with the first level low pressure passage
3
at one end and connected with the second low pressure on-off valve
12
at the other end. The space defined by the four valves (first high pressure on-off valve
4
, second high pressure on-off valve
11
, first low pressure on-off valve
5
and second low pressure on-off valve
12
) and the compressor
1
operates as a working space (or an operating space) of the pulse tube refrigerator
201
.
FIG. 12
illustrates valve on-off operations of the first high pressure on-off valve
4
, the second high pressure on-off valve
11
, the first low pressure on-off pressure valve
5
and the second low pressure on-off valve
12
in accordance with the operation of the pulse tube refrigerator
201
of FIG.
11
. In the drawing, bold lines show the valve-on conditions and fine lines show the valve-off conditions of the valves. As shown in
FIG. 12
, the four valves, i.e., first high pressure on-off valve
4
, second high pressure on-off valve
11
, first low pressure on-off valve
5
, and second low pressure on-off valve
12
are turned on in sequence. By sequentially turning on the four valves, the phase between the pressure changes of the operational gas, and movements (displacements) thereof, is controlled to generate a refrigeration output within the pulse tube
10
and extract a low temperature at the cold head
9
. (see
FIG. 11
)
The above explained conventional four valve type pulse tube refrigerator and other conventional four valve type refrigerators have basic problems which cannot be solved, due to their operating principle. The problems are the low refrigeration efficiency and the lack of operating stability. The main cause of the low refrigeration efficiency is the operational loss caused by the returning of the operational gas from the operating space into the compressor. That is, a portion of the operational gas which has entered the operating space from the compressor
1
through the second high pressure on-off valve
4
during the operation of pulse tube refrigerator returns to the compressor
1
again from the second level low pressure passage
14
through the second low pressure on-off valve
12
. The compressor
1
therefore has to work extra due to the unnecessary flow of the returning gas thereinto. This extra work of the compressor causes a low efficiency of the refrigerator.
The main cause of the lack of stability is the generation of a one way flow gas whose amount exceeds a fixed amount defined by the cycle within the pulse tube
10
due to the operational gas flow (in and out) from the compressor
1
in both directions from regenerator
8
side and pulse tube
10
side. (This one way flow gas may be defined as a circulation flow gas if the flow passages are included.)
The one way or circulation flow gas runs from the compressor
1
into the operating space through the first level high pressure passage
2
and the first high pressure on-off valve
4
and returns to the compressor
1
through the second low pressure on-off valve
12
and the second level low pressure passage
14
. In another flow route, the operating gas runs from the compressor
1
into the operating space through the second level high pressure passage
13
and the second high pressure on-off valve
11
and returns to the compressor
1
through the first low pressure on-off valve
5
and the first level low pressure passage
3
. Such a flow route may be variable depending on the operational conditions of the refrigerator
201
. The above extra one way or circulation flow causes instability of the operation of the refrigerator.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the above drawbacks of the conventional refrigerator.
It is another object of the present invention to improve the efficiency of the refrigeration.
It is a further object of the present invention to improve the stability of the refrigerator under operation by avoiding the generation of the one way flow of the operating gas.
In order to solve the above and other technical problems, the pulse tube refrigerator according to this invention includes a compressor, a first high pressure on-off valve connected with an outlet port of the compressor through a first level high pressure passage, a first low pressure on-off valve connected with an inlet port of the compressor through a first level low pressure passage, a regenerator having a low temperature end and a high temperature end, the regenerator being connected with the first high pressure on-off valve and the first low pressure on-off valve at the high temperature end of the regenerator, a cold head connected with the low temperature end of the regenerator, a pulse tube having a low temperature end and a high temperature end and connected with the cold head at the low temperature end thereof, a second high pressure on-off valve connected with the high temperature end of the pulse tube, a second low pressure on-off valve connected with the high temperature end of the pulse tube, a second level high pressure passage connected with the first level high pressure passage at one end and connected with the second high pressure on-off valve at the other end, a second level low pressure passage connected with the first level low pressure passage at one end and connected with the second low pressure on-off valve at the other end, a high pressure side cylinder provided in the second level high pressure passage, a high pressure side partition element reciprocally provided within the high pressure side cylinder and fluid tightly dividing the high pressure side cylinder into a first high pressure space connected with the first level high pressure passage and a second high pressure space connected with the second high pressure on-off valve, a low pressure side cylinder provided in the second level low pressure passage and a low pressure side partition element reciprocally provided within the low pressure side cylinder and fluid tightly dividing the low pressure side cylinder into a first low pressure space connected with the first level low pressure passage and a second low pressure space connected with the second low pressure on-off valve within the low pressure side cylinder.
According to the feature of the invention, sinc
Inoue Tatsuo
Kawano Shin
Nogawa Masafumi
Zhu Shaowei
Aisin Seiki Kabushiki Kaisha
Doerrler William
Drake Malik N.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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