Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2000-09-21
2002-02-05
Doerrler, William (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
Reexamination Certificate
active
06343475
ABSTRACT:
This application is based on Japanese Patent Applications HEI 11-275981, filed on Sep. 29, 1999 and 2000-73030, filed on Mar. 15, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a pulse tube refrigerator, and more particularly to a pulse tube refrigerator with improved housing structures for regenerating material or the like. The pulse tube refrigerator is used with precise physical and chemical apparatuses such as an NMR and an electron microscope.
b) Description of the Related Art
Ultra low temperature refrigerators such as pulse tube refrigerators are widely used for maintaining a low temperature environment for precise physical and chemical apparatuses such as an NMR and an electron microscope.
FIG. 7
is a cross sectional view showing the main part of a conventional pulse tube refrigerator
1
. The pulse tube refrigerator
1
has: a compressor
2
; a valve unit
3
for switching between high and low pressures; a high temperature end block
4
; a low temperature end block (cooling end block)
5
; a regenerator
6
; a pulse tube
7
; a flow rectifier
8
at a regenerator low temperature end; a flow rectifier
9
at a pulse tube low temperature end; and a flow rectifier
10
at a pulse tube high temperature end.
The high temperature end block
4
has a working gas supply port
11
and a working gas reciprocal port
12
. Working gas or fluid such as helium gas is pulsatively supplied from the working gas supply port
11
, via the inside of a supply port space
13
, and to the regenerator
6
. A buffer tank
15
is coupled to the working gas reciprocal port
12
. An orifice
14
is provided in the working gas reciprocal port
12
. The high temperature end block
4
is mounted on a mount flange
16
with mount bolts
17
.
The regenerators is constituted of a regenerator case
18
disposed between the high temperature block
4
(mount flange
16
) and the low temperature end block
5
, and a. regenerating material
19
housed in the regenerator case
18
. As the regenerating material
19
, copper material, stainless steel material, metal fibers or punching metal is used. The regenerator
19
is filled in the regenerator case
18
at a predetermined density. While the working gas passes through the inside of the regenerator
6
, regeneration is performed between the working gas and regenerating material
19
to cool the regenerating material
19
.
The low temperature end block
5
is disposed facing the high temperature end block
4
at a predetermined distance. The regenerator
6
and pulse tube
7
are disposed generally in parallel between the low temperature end block
5
and high temperature end block
4
. A commuter space
20
is formed in the low temperature end block
5
to make the lower temperature end of a gas passage in the regenerator
6
communicate with the low temperature end of the gas passage in the pulse tube
7
. In the commuter space
20
, the flow rectifier
8
at the regenerator low temperature end is disposed in a space
21
on the regenerator
6
side, and the flow rectifier
9
at the pulse tube low temperature end is disposed in a space
22
on the pulse tube
7
side.
The flow rectifier
8
at the regenerator low temperature side is made of flow rectifying material
23
(first flow rectifying material) filled in the space
21
. The flow rectifier
9
at the pulse tube low temperature side is made of flow rectifying material
24
(second flow rectifying material) filled in the space
22
.
The high temperature end of the pulse tube
7
communicates with the working gas reciprocal port
12
via the flow rectifier
10
at the pulse tube high temperature end.
The flow rectifier
10
at the pulse tube high temperature end is made of flow rectifying material
26
(third flow rectifying material) filled in a space
25
formed in the high temperature end block
4
.
The flow rectifying materials
23
,
24
and
26
are, for example, metal meshes or punching metal.
The working gas is pulsatively supplied into the regenerator
6
via the working gas supply port
11
and supply port space
13
. This working gas is also supplied into the pulse tube
7
via the flow rectifier
8
, commuter space
20
and flow rectifier
9
. The pressure and volume of the working gas in the pulse tube
7
are changed. The flow rectifiers
9
and
10
rectify the working gas flow in the pulse tube
7
. The phases of the pressure change and volume change are controlled by the orifice
14
and buffer tank
15
. Heat is absorbed in the low temperature end block
5
.
In the conventional pulse tube refrigerator
1
, the regenerating material
19
is directly filled in the regenerator case
18
. Similarly, the flow rectifying material
23
is directly filled in the regenerator side space
21
, the flow rectifying material
24
is directly filled in the pulse tube side space
22
, and the flow rectifying material
26
is directly filled in the orifice side space
25
.
During the operation of the pulse tube refrigerator
1
, if impurities such as water contents and other fluids are solidified, the regenerating material
19
or flow rectifying material
23
,
24
or
26
may be clogged with the impurities. In such a case, the cooling performance may be lowered. In order to recover the original cooling performance, the temperature of the clogged areas are raised to remove solidified fluid contents.
However, if impurities are oil or the like flowed from the compressor
2
, these impurities are difficult to be removed by raising the temperature of the clogged areas. In this cases it is necessary to replace the regenerating material
19
or flow rectifying material
23
,
24
or
26
by new one.
In order to replace the regenerating material
19
or flow rectifying material
23
,
24
or
26
, it is necessary to stop the operation of a precise physical and chemical apparatus (cooling object) cooled with the pulse tube refrigerator
1
and raise the temperature thereof. This operation stop and temperature rise lower a running efficiency of the apparatus. In addition, a cooling operation is again required after material replacement, which results in a large cost and work and a long work time.
Furthermore, since the regenerating material
19
and flow rectifying materials
23
,
24
and
26
are directly filled in the spaces, a replacement work itself is neither simple nor efficient.
Another type of a conventional pulse tube refrigerator has a structure that a flow rectifier (not shown) for communicating the working gas supply port
11
with the high temperature end of the regenerator
6
is provided by directly filling flow rectifying material (fourth flow rectifying material) in the supply port space
13
of the high temperature end block
4
. Also with this pulse tube refrigerator having such a structure, a replacement work for flow rectifying material is not simple and a maintenance efficiency is lowered.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a pulse tube refrigerator capable of cold maintenance without an operation stop and temperature rise of a precise physical and chemical apparatus, by using a cartridge type regenerator and cartridge type flow rectifiers easy to be replaced.
It is another object of the present invention to provide a pulse tube refrigerator capable of easily replacing a clogged regenerating material or flow rectifying material.
According one aspect of the present invention, there is provided a pulse tube refrigerator comprising: a first pulse tube, a high temperature end and a low temperature end being defined at both ends thereof, and having an inner space; a first regenerator case of a tubular type, a high temperature end and a low temperature end being defined at both sides thereof; a first regenerator including a first cartridge case and a first regenerating material filled in the first cartridge case, the first cartridge case being removably inserted into said first regenerator case; a first passage communicating a space in
Arent Fox Kintner & Plotkin & Kahn, PLLC
Doerrler William
Drake Malik N.
Sumitomo Heavy Industries, Inc.
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