Refrigeration – Automatic control – Refrigeration producer
Patent
1994-12-15
1998-06-30
Tanner, Harry B.
Refrigeration
Automatic control
Refrigeration producer
62230, F24F 1102
Patent
active
057717044
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an operation control apparatus for an air conditioner, and in particular, to a current decreasing control of a motor for driving a compressor.
BACKGROUND ART
Conventionally, there has been an air conditioner wherein a compressor of which capacity is controlled by an inverter, a four-way directional control valve, an outdoor heat exchanger, an electrically operated expansion valve, and an indoor heat exchanger are serially connected to one another, and wherein a frequency of the inverter is controlled based on a temperature difference between a room temperature and a set temperature to control the capacity of the compressor by increasing and decreasing the capacity ('89 Daikin skyair technical guide <service parts list>, issued in June 1989, p. 244).
When a supply current to a motor built in the compressor reaches a specified value in a stage in which a high load is applied to the compressor, the operating frequency is reduced to prevent the supply current from abnormally increasing.
In the above-mentioned air conditioner, the control of the current supplied to the motor of the compressor is effected in a manner as follows. As shown in FIGS. 7(a) and 7(b), there is provided a decreasing interval X1 in which the operating frequency is reduced in steps when the supply current (DC current before the inverter) flowing through the motor of the compressor reaches a specified value Is lower than a peak current Im. There is further provided a retaining interval X2 in which the present operating frequency is retained for three minutes when the supply current reduces to a level below the specified value Is. After escaping from the retaining interval X2, the current control enters into a normal control operation.
However, in the above-mentioned current control operation, there is such a problem that the operating frequency of the motor hunts to cause noise which cyclically changes, offending the ear. Furthermore, there is another problem that the durability of the compressor reduces due to the hunting of the operating frequency.
SUMMARY OF THE INVENTION
The present invention was made in view of the aforementioned problems, and it is an object of the present invention to prevent noise created by the possible hunting of the operating frequency by stabilizing the operating frequency and to thus improve the durability of the compressor.
In order to achieve the aforementioned object, an embodiment of the present invention involves retaining an operating frequency at a specified value, and thereafter gradually increasing the operating frequency.
Practically as shown in FIG. 1, the measures of the invention relevant to a first embodiment is based on an air conditioner which includes a refrigerant circuit (9) constituted by serially connecting a variable-capacity compressor (1), a heat source side heat exchanger (3), an expansion mechanism (5), and a heat use side heat exchanger (6).
Then there is provided a frequency controller (41) for controlling capacity of the compressor (1) by changing at a predetermined speed an operating frequency for driving the compressor (1), and a current detector (R2) which detects a current flowing through of the compressor (1). There is further provided a frequency reducer means (42) which receives a detection signal from the current detector means (R2) and outputs a signal for reducing the operating frequency of the compressor (1) to the frequency controller (41) when a supply current of the compressor (1) reaches a specified value. There is further provided a frequency retainer means (43) which receives the detection signal from the current detector (R2), and when the supply current of the compressor (1) is reduced to a specified value, completes the frequency reducer, operation of the frequency reducing (42) and retains the present operating frequency until a specified time elapses. There is further provided a frequency increaser means (44) which outputs an increasing signal for increasing the operating frequency at a speed slower
REFERENCES:
patent: 4735058 (1988-04-01), Umezu et al.
patent: 4736595 (1988-04-01), Kato
patent: 4968338 (1990-11-01), Sugiyama
patent: 5107685 (1992-04-01), Kobayashi
patent: 5209075 (1993-05-01), Kim
Daikin Skyair Technical Guide, Jun. 1989, service parts list.
Nakajima Hiroto
Suda Tetsuya
Daikin Industries Ltd.
Tanner Harry B.
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