Refrigerator and method of filling it with coolant

Details Refrigerator and method of filling it with coolant Refrigerator and method of filling it with coolant

1999-07-14

2001-05-22

McDermott, Corrine (Department: 3744)

Refrigeration

With means for charging closed refrigeration producing system

C062S077000

Reexamination Certificate

active

06233961

ABSTRACT:

TECHNICAL FIELD
This invention relates to a refrigerating apparatus and a method of charging refrigerant into the apparatus, and particularly relates to an improved technique of charging various kinds of refrigerants such as non-azeotropic mixed refrigerant.
BACKGROUND ART
In conventional refrigerating apparatuses using single refrigerant such as R22, the charging of refrigerant into refrigerant circuitry is executed in the following manner, as disclosed in “Shinban Dai-4-Han, Reito-Kucho Binran (Kiso-Hen)”, pp.704-705, edited by Japan Society of Refrigerating and Air Conditioning Engineering.
Specifically, first, a refrigerant cylinder is connected through a tube to a refrigerant charge valve of the refrigerant circuitry previously maintained under vacuum. Then, the refrigerant charge valve is opened to let refrigerant in the refrigerant cylinder flow into the refrigerant circuitry due to the pressure difference between the insides of the refrigerant cylinder and the refrigerant circuitry.
As the refrigerant is charged into the refrigerant circuitry, the pressure in the refrigerant circuitry is increased. Therefore, the pressure difference between the insides of the refrigerant cylinder and the refrigerant circuitry becomes gradually lessened so that the charging speed of refrigerant is gradually reduced. In particular, when the air temperature at the outdoors where the refrigerant cylinder is put, i.e., the open-air temperature, is low, the pressure in the refrigerant cylinder is low and therefore the pressure difference readily becomes lessened.
Accordingly, the amount of refrigerant charged into the refrigerant circuitry per unit time is decreased. As a result, the charging speed of refrigerant becomes extremely slow in a short time. In other words, even though the pressure in the refrigerant cylinder is higher than that in the refrigerant circuitry, there arises a condition that substantially little refrigerant can be charged into the refrigerant circuitry.
If such a condition arises, the following measures are generally taken in order to increase the charging speed of refrigerant.
Specifically, the refrigerant cylinder is connected to a valve provided in the line on the suction side of a compressor. And, refrigerant is supplied to the refrigerant circuitry through the valve with the compressor operated. In this manner, a large pressure difference is ensured between the insides of the refrigerant circuitry and the refrigerant cylinder, thereby increasing the charging speed of refrigerant.
PROBLEMS TO BE SOLVED
In the case where refrigerant is charged into the line on the suction side of the compressor, however, the following problems arise.
A first problem is that when refrigerant is charged in its liquid state from the refrigerant cylinder, liquid refrigerant is sucked into the compressor, resulting in the possibility of breakage of the compressor due to liquid compression.
Another problem is that when refrigerant is charged in its gas state from the refrigerant cylinder and the refrigerant is non-azeotropic mixed refrigerant, the ratio of composition of the mixed refrigerant in a state of existing in the refrigerant cylinder becomes different from that of the mixed refrigerant in a state of having been charged into the refrigerant circuitry.
Specifically, in recent years, non-azeotropic mixed refrigerant such as R407C has come into increasing use as alternative refrigerant in view of global-scale environmental problems. The non-azeotropic mixed refrigerant has a characteristic that the ratio of composition in its gas state is different from that in its liquid state due to different boiling points of respective refrigerants forming the mixed refrigerant. In general, the non-azeotropic mixed refrigerant is adjusted in its ratio of composition when it is in a liquid state, and is then stored in the refrigerant cylinder as it is in a liquid state. Therefore, in the above-mentioned case where the mixed refrigerant has been charged in its gas state into the refrigerant circuitry, there arises a problem that the ratio of composition of the mixed refrigerant is changed. To be more specific, when the mixed refrigerant is charged in its gas state into the refrigerant circuitry, the ratio of composition of the mixed refrigerant in a state of having been charged into the refrigerant circuitry becomes different from that of the mixed refrigerant in a state of existing in the refrigerant cylinder, and therefore the mixed refrigerant has different properties between both the states. Accordingly, if the mixed refrigerant is charged in gas refrigerant form into the refrigerant circuitry, it cannot exhibit performance as designed. This extremely deteriorates performance of the refrigerating apparatus.
Consequently, for the non-azeotropic mixed refrigerant, it is impossible to adopt the method of charging it in a gas state into the refrigerant circuitry from the line on the suction side of the compressor in operation. Therefore, the mixed refrigerant must be charged with the compressor coming to a halt, which requires much time to complete the charging of refrigerant into the refrigerant circuitry.
Under such circumstances, there has been demand for charging refrigerant, particularly non-azeotropic mixed refrigerant, in a liquid state into the refrigerant circuitry without impairing reliability of the compressor.
The present invention has been made in view of the above problems, and therefore it is an object of the present invention is to attain prompt charging of refrigerant into the refrigerant circuitry without impairing reliability of the compressor.
DISCLOSURE OF INVENTION
Summary of Invention
To attain the above object, in the present invention, a refrigerant charging section (
40
A) is provided in part of refrigerant circuitry located far from a compressor (
15
,
22
) and is held at low pressure by closing the upstream side of the refrigerant charging section (
40
A) while driving the compressor (
15
,
22
), and new refrigerant is charged in its liquid state from the refrigerant charging section (
40
A) while high-pressure refrigerant is being released to the low-pressure-side line to prevent an excessive pressure rise in the high-pressure-side line and an excessive pressure drop in the low-pressure-side line.
Means for Solving the Problems
Specifically, a refrigerating apparatus of the present invention includes refrigerant circuitry (
11
) in which a compressor (
15
,
22
), a heat-source-side heat exchanger (
17
), a pressure reduction mechanism (
18
), and a heat-use-side heat exchanger (
20
) are sequentially connected. Further, the refrigerant circuitry (
11
) includes: shutoff means (
23
) provided between the heat-source-side heat exchanger (
17
) and the heat-use-side heat exchanger (
20
); a refrigerant charging section (
40
A) provided downstream of the shutoff means (
23
) and brought into communication with a refrigerant source (
31
) when refrigerant is charged into the refrigerant circuitry (
11
); and a pressure relieving circuit (SVP) for conducting refrigerant in a high-pressure-side line of the refrigerant circuitry (
11
) to a low-pressure-side line thereof when the refrigerant is charged into the refrigerant circuitry (
11
) with the compressor (
15
,
22
) driven.
The pressure relieving circuit may be formed of a refrigerant passage (SVP) for providing communication between the high-pressure-side and low-pressure-side lines of the refrigerant circuitry (
11
), and may be provided with auxiliary shutoff means (
25
) that is opened during the charging of refrigerant.
The pressure relieving circuit (SVP) may include a first circuit (SVP
1
) for conducting refrigerant in a line on the discharge side of the compressor (
15
,
22
) to a line on the suction side thereof.
The pressure relieving circuit (SVP) may include a second circuit (SVP
2
) for conducting refrigerant in a line downstream of the heat-source-side heat exchanger (
17
) to a line on the suction side of the compressor (
15
,
22
).
The shutoff means (
23
) may be provided between the heat-source-si

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