Operation method and operation apparatus for multi-system...

Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...

Reexamination Certificate

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C062S055500

Reexamination Certificate

active

06655154

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an operation method and an operation apparatus for multi-system refrigerators, and a refrigerating apparatus. In particular, the present invention relates to an operation method and an operation apparatus for multi-system refrigerators for supplying multiple refrigerators with gas compressed by one or more compressors through valves provided for the individual refrigerators. The present invention also relates to a refrigerating apparatus using these operation method and apparatus.
2. Description of the Related Art
A Gifford-McMahon (GM) refrigerator and a pulse tube refrigerator are known as a refrigerator for using a phase difference between a pressure change and a volume change of an operating gas to generate a very low temperature. When refrigerators of this type are provided at multiple locations on a large apparatus such as sputtering apparatus for a semiconductor manufacturing apparatus, a single compressor
10
is shared by a plurality of refrigerators (three in this drawing)
31
,
32
, and
33
as shown in
FIG. 1
, instead of providing multiple compressors generating a high pressure and a low pressure for the individual refrigerators to reduce the cost and the energy consumption. In this case, valves
21
,
22
, and
23
(such as rotary valves) are provided for the individual refrigerators
31
,
32
, and
33
to supply the refrigerators
31
,
32
, and
33
with gas (such as helium gas) which is compressed by the single compressor
10
, and is supplied alternately through a high pressure line
12
at a high pressure, and a low pressure line
14
at a low pressure.
The refrigerators
31
,
32
, and
33
conduct a refrigerating process, thereby repeating an adiabatic expansion for generating a low temperature state, resulting in refrigerating first refrigerating stages
31
B,
32
B, and
33
B of cylinders
31
A,
32
A, and
33
A to 30 to 100 K, and refrigerating second refrigerating stages
31
C,
32
C, and
33
C to 4 to 20 K.
In the drawing, motors
41
,
42
, and
43
drive the valves
21
,
22
, and
23
to respectively rotate. A power supply line
50
for driving refrigerators provides the motors
41
,
42
, and
43
with the same drive signal.
However, when the single compressor
10
is used to drive multiple refrigerators
31
,
32
, and
33
, a difference is generated in refrigerating performance of the individual refrigerators
31
,
32
, and
33
among one another. This is because the timings of the valves for supplying the helium gas in the individual refrigerators
31
,
32
, and
33
are fixed when the power supply is turned on. As a result, when intake timings overlap one another, more gas flows to the refrigerator which takes in gas first, thereby generating such a phenomenon as an imbalance in gas quantity flown to the individual refrigerators. Thus, when a valve opens in one refrigerator immediately after another valve opens in the other refrigerator, the helium gas is hardly supplied for this valve due to decrease of the supplied gas pressure, thereby presenting insufficient cooling performance. In addition, the helium gas flowing into a more cooled refrigerator is cooled further, thereby having a larger density. As a result, additional helium gas is supplied, thereby cooling this low-temperature refrigerator even further. On the other hand, since the helium gas hardly flows to a less cooled refrigerator, the refrigerator is not cooled sufficiently.
To solve this problem, Japanese Patent Laid-Open Publication Nos. Hei. 3(1991)-15677 and Hei. 4(1992)-272486 disclose such a control method as observing valve timing of the individual valves to feed back the valve timing, thereby controlling the timings for opening/closing are at an equal interval to one another.
However, since it is necessary to observe the valve timing by, for example, detecting currents supplied for the motors
41
,
42
, and
43
for driving the valves
21
,
22
, and
23
, the complexity of the system increases, resulting in increasing the cost.
SUMMARY OF THE INVENTION
The present invention was devised to solve the conventional problem described above, and has an object of providing a simple constitution for solving the imbalance of the cooling performance among refrigerators without observing valve opening/closing timing.
An operation method for multi-system refrigerators of the present invention supplies a plurality of refrigerators with gas compressed by a single compressor through valves provided for the respective refrigerators. This method solves the problem above by shifting an opening/closing frequency of each of the valves slightly to one another.
In this method, a shift amount of the opening/closing frequencies of the valves may be changed depending on the number of the refrigerators. For example, the shift amount is decreased as the number of the refrigerators increases.
An operation apparatus for multi-system refrigerators of the present invention supplies a plurality of refrigerators with gas compressed by a single compressor through valves provided for the respective refrigerators. This operation apparatus solves the problem above by including inverters for slightly shifting an opening/closing frequency of each of the valves to one another.
The present invention also provides a refrigerating apparatus including the operation apparatus described above.
Further, in the present invention, the refrigerators described above may be used as cryopumps, thereby resolving an imbalance in performance among the cryopumps.
With the present invention, it is possible to prevent an overlap of the valve timing with a very simple and inexpensive constitution without means for observing the valve timing, thereby balancing the performance among refrigerators.


REFERENCES:
patent: 3656540 (1972-04-01), Henrici
patent: 5010737 (1991-04-01), Okumura et al.
patent: 03-015677 (1991-01-01), None
patent: 04-272486 (1992-09-01), None

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