Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1998-08-24
2001-02-27
Wayner, William (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S228300, C062S502000
Reexamination Certificate
active
06192696
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerant circuit of a refrigerating apparatus using a non-azeotropic refrigerant and to refrigerant circuit control.
FIG. 15
is a conventional refrigerating apparatus in which a non-azeotropic refrigerant is used and which is disclosed in, for instance, Japanese Patent Application. Laid-Open No. 75280/1996. This refrigerating apparatus is provided with a refrigerating circuit in which a compressor
1
, a condenser
3
, a first capillary tube
4
, an evaporator
5
, and an accumulator
6
are sequentially connected in loop form by the piping and in which a non-azeotropic refrigerant circulates; a bypass pipe
8
which bypasses the refrigerant circuit from the pipe between the compressor
1
and the condenser
3
to the pipe between the compressor and the evaporator and in which a cooling means
9
and a second capillary tube
10
are connected; a temperature detector
12
and a pressure detector
13
for detecting the temperature and pressure of an outlet portion of the second capillary tube; and a composition calculator
14
for calculating the composition of the refrigerant circulating in the refrigerant circuit. The composition of the refrigerant circulating in the refrigerant circuit can be calculated in this refrigerating apparatus, and the operation of the refrigerating apparatus is controlled on the basis of this composition of the refrigerant.
With the conventional technology, however, there has been no method for maintaining the condensing temperature and the evaporating temperature to fixed levels as a means for appropriately controlling the operation of the refrigerating apparatus using a non-azeotropic refrigerant. Namely, since the condensing temperature and the evaporating temperature have been determined with the cyclic composition fixed or with the cyclic composition fixed for each operating condition, it has been impossible to follow up, or sufficiently follow up, changes in the condensing temperature and evaporating temperature with respect to changes in the cyclic composition. In addition, it has been impossible to demonstrate a predetermined capacity at the time of gas leakage or erroneous charging of the refrigerant.
Further, with the refrigerating apparatus using a non-azeotropic refrigerant, if the cyclic composition of the refrigerant changes, the condensing pressure and the evaporating pressure change in a case where the condensing temperature and the evaporating temperature change. For this reason, the flow rate of the refrigerant circuit changes, so that it is impossible to secure a stable capacity, and it is difficult to secure subcooling on the inlet side of a throttling device. Namely, there has been a problem in compatibility in the securing of subcooling and the securing of the refrigerant flow rate.
Further, with the refrigerating apparatus using a non-azeotropic refrigerant as well, in the operation at a low outdoor air temperature, since the refrigerant which left the compressor becomes condensed in the refrigerant pipe where the refrigerant is cooled, the amount of refrigerant supplied to the compressor temporarily becomes smaller than the amount of refrigerant which leaves the compressor, with the result that the pressure within the suction portion of the compressor declines, leading to the malfunction of the compressor.
Further, since the pressure is higher for R.407C than R.22 at the same temperature, the malfunction of the refrigerating apparatus due to an excess rise in the pressure at the discharge portion of the compressor has been more liable to occur in the case of the refrigerating apparatus using R.407C than in the case of the refrigerating apparatus using R.22.
In addition, with refrigerant R.407C, the malfunction of the compressor due to corona discharge under vacuum has been more liable to occur than refrigerant R.22.
In addition, with the refrigerating apparatus using refrigerant R.407C and ester oil and ether oil which are refrigerating machine oils used for R.407, sludges which adversely affect the refrigerating apparatus have been liable to occur in large amounts.
In addition, with the non-azeotropic refrigerant, it has been impossible to accurately detect the compression of the refrigerant in the compressor, with the result that a malfunction has been liable to occur in the compressor.
In addition, with the non-azeotropic refrigerant, it has been impossible to accurately detect the excessive superheating of the compressor on the discharge side of the compressor.
In addition, with the non-azeotropic refrigerant, it has been impossible to accurately detect a decline in the concentration of the lubricating oil in the compressor due to excessive supply of liquid refrigerant.
In addition, with the non-azeotropic refrigerant, it has been difficult to obtain subcooling at the condenser outlet.
SUMMARY OF THE INVENTION
The present invention aims to overcome the above-described problems, and its object is to make it possible to use a non-azeotropic refrigerant (including a pseudo-azeotropic refrigerant) in a refrigerating apparatus without trouble.
In accordance with a first aspect of the present invention, there is provided a refrigerating apparatus using a non-azeotropic refrigerant and provided with a refrigerant circuit in which a capacity variable compressor, a heat source unit-side heat exchanger, a throttling device, and a using-side heat exchanger are connected by the piping, a capability variable fan for the heat source unit-side heat exchanger, a first pressure detector at a discharge pipe of the compressor, a second pressure detector at a suction pipe of the compressor, and a refrigerant cyclic-composition detecting device, comprising:
fan/compressor capacity controlling means for determining a condensing temperature of the heat source unit-side heat exchanger or the using-side heat exchanger on the basis of a refrigerant cyclic composition detected by the cyclic-composition detecting device and a pressure detected by the first pressure detector, or determining an evaporating temperature of the heat source unit-side heat exchanger or the using-side heat exchanger on the basis of the refrigerant cyclic composition detected by the cyclic-composition detecting device and a pressure detected by the second pressure detector, so as to control the capacity of the compressor and the capability of the fan for the heat source unit-side heat exchanger so that the condensing temperature and the evaporating temperature are set to respective predetermined target values.
In accordance with a second aspect of the present invention, there is provided a refrigerating apparatus using a non-azeotropic refrigerant and provided with a refrigerant circuit in which a compressor, a heat source unit-side heat exchanger, a throttling device, and a using-side heat exchanger are connected by the piping, a first pressure detector at a discharge pipe of the compressor, a second pressure detector at a suction pipe of the compressor, a refrigerant cyclic-composition detecting device, and a temperature detector for detecting the temperature of the refrigerant on an upstream side of the throttling device, comprising:
a subcooling calculator for determining a condensing temperature of the heat source unit-side heat exchanger or the using-side heat exchanger on the basis of a refrigerant cyclic composition detected by the cyclic-composition detecting device and a pressure detected by the first pressure detector, for calculating a subcooling value of the refrigerant which enters the throttling device on the basis of the condensing temperature and the temperature detected by the temperature detector; and
a throttling-device minimum opening outputting device for calculating a minimum opening of the throttling device on the basis of the refrigerant cyclic composition detected by the cyclic-composition detecting device, the pressure detected by the first pressure detector, and a pressure detected by the second pressure detector, for comparing the calculated minimum opening with an opening command
Kasai Tomohiko
Shimamoto Daisuke
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wayner William
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