JPH04203744A - Low temp. open air cooling control system - Google Patents

Abstract

PURPOSE:To reduce a delivery pressure to a proper level and to reduce consumption of a power by a method wherein an indoor air temperature detecting means is provided, and when the indoor air temperature is high, the number of revolutions control pattern of an outdoor fan motor is corrected to the high rotation side. CONSTITUTION:When an operation SW 12 is turned ON, a relay 1b for a compressor and a relay 4c for an indoor fan are respectively excited through an input circuit 9, a CPU 10, and a driver 11. A relay is turned ON, and a motor 1a for a compressor and an indoor fan motor 4a are started. A temperature detected by a thermistor 6 for indoor air temperature and a thermistor 7 for an outdoor air temperature is inputted to a microcomputer substrate, and the number of revolutions of an outdoor fan is controlled according to a control program. When an outdoor air temperature is increased by means of an outdoor air temperature, a vaporizing amount is increased, and a delivery pressure and a suction pressure are changed in an increasing direction. Thus, the pressure values are kept at a constant value as much as possible, a secondary voltage value is increased, and control is made such that a heat exchange amount of a condenser is increased through the increase of the number of revolutions of an outdoor fan motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fan controller that prevents a drop in discharge pressure even when the outside air temperature is low and enables stable cooling operation.

[Conventional technology]

In the conventional system, as described in Japanese Patent Application Laid-open No. 53-110245, the power supply phase of the blower motor is controlled by detecting the condensing temperature, the blown air temperature, and the evaporation temperature.

[Problem to be solved by the invention]

Since the above conventional technology determines the rotation speed of the outdoor fan motor only depending on the outdoor air temperature, it does not take into consideration the fact that the discharge pressure changes with changes in the indoor air temperature, and even when the indoor air temperature is low, the In order to maintain the evaporation pressure to prevent frost formation on the heat exchanger, the discharge pressure is set to be high, so when the indoor air temperature rises, the evaporation pressure, that is, the suction pressure, increases, and the discharge pressure is necessary. As a result, there is a problem in that the power consumption increases.

An object of the present invention is to detect the indoor air temperature and, when the indoor air temperature is high, lower the discharge pressure to an appropriate level, thereby reducing power consumption compared to conventional systems.

[Means to solve the problem]

In order to achieve the above object, the present invention detects the indoor air temperature and sets the rotation speed of the outdoor fan motor to be high when the indoor air temperature is high.

[Effect]

When the indoor air temperature is high, the rotation speed of the outdoor fan motor is increased, but it is set so that it does not fall below an appropriate level, so there is no abnormal drop in discharge pressure.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a system diagram when the control method is applied to an air-cooled air conditioner, and the refrigeration cycle consists of a compressor 1. Air-cooled condenser 2. Composed of a pressure reducing device 3 and an evaporator 4, the air-cooled condenser 2 exchanges heat with outdoor air by an outdoor fan motor 2a and an outdoor fan 2b, and the evaporator 4 is heated indoors by an indoor fan motor 4a and an indoor fan 4b. heat exchanged with air. Further, a thermistor 6 for detecting indoor air temperature and a thermistor 7 for detecting outdoor air temperature are connected to the control device 5 as control inputs, and the compressor 1. outdoor fan motor 2a,
Controls the indoor fan motor 4a.

FIG. 2 shows an example of a control circuit, in which the control device 5 includes an input circuit 9. Microcomputer board 10. Driver 11° phase angle control device 8. Compressor relay 1b, indoor fan motor relay 4
Contains c. In addition, the input circuit 9 has the operation 5W12. A thermistor 6 for detecting indoor temperature and a thermistor 7 for detecting outdoor temperature are connected, and the compressor motor 1 is connected to the compressor relay 1b.
Indoor fan motors 4a are connected to the indoor fan motor relays 4c.

The operation will be explained below. When the operation switch is turned on, the input circuit 9. CPU10. The compressor relay 1b and the indoor fan relay 4c are excited through the driver 11, and the relays are turned on, starting the compressor motor la and the indoor fan motor 4a. Further, the temperature detected by the indoor air temperature thermistor 6 and the outdoor air temperature thermistor is input to the microcomputer board, and the rotation speed of the outdoor fan motor is controlled by a control program. At this time, the rotation speed control is actually performed by the phase angle control device 8.

The control specifications for the rotation speed are shown in FIGS. 3 and 4. The broken line in FIG. 3 is the control specification when the indoor temperature is 27°C, and the solid line is the control specification when the indoor temperature is 21°C. Figure 4 shows the outside temperature of 15
The specifications of the secondary voltage with respect to indoor temperature changes in the case of °C are shown. Even if the outdoor air temperature is the same, when the indoor temperature rises, the amount of evaporation increases and the discharge pressure increases.

The suction pressure continues to increase. Therefore, in order to keep these pressure values as constant as possible, control is performed to increase the amount of heat exchanged by the condenser by increasing the secondary voltage value and increasing the rotational speed of the outdoor fan motor. This situation is shown in FIG. However, this graph is for when the indoor air temperature is 27°C.

The dashed straight line ■ is for the case where no fan control is performed, the curve ■ drawn by the two-dot chain line is for the conventional method that detects only the outdoor air temperature, and the solid line curve 0 is for the case where the present invention detects both the outdoor and indoor air temperatures. This is a method for detecting Further, the minimum value of the evaporation pressure at which the surface of the indoor heat exchanger does not freeze is shown by a dashed-dotted line (■), and the minimum discharge pressure limit required for proper operation of the compressor is shown by a dashed-dotted line (■). In this way, both evaporation pressure and discharge pressure can be maintained at appropriate pressures that do not exceed their limits.
When the indoor air temperature is high, the discharge pressure is lower than that of the conventional method.
Moreover, the input value of the compressor can also be lowered. According to this embodiment, when the indoor air temperature is high, the compressor motor is reduced by 5 to 10% compared to the conventional system.

〔Effect of the invention〕

According to the present invention, both indoor and outdoor air temperatures are detected,
By controlling the rotation speed of the outdoor fan motor in consideration of the influence of both on the refrigeration cycle, the discharge pressure can be maintained at an appropriate level, and there is an energy saving effect.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram of an embodiment of the present invention, Fig. 2 is a control circuit diagram, Fig. 3 is a control characteristic diagram of the outdoor fan motor depending on the outdoor temperature, and Fig. 4 is a control of the outdoor fan motor depending on the indoor temperature. The characteristic diagram, FIG. 5, is an explanatory diagram showing changes in discharge pressure, suction pressure, and compressor input when the outdoor temperature changes. 1... Compressor, 1a... Compressor motor, 1b...
・Compressor motor relay, 2...Air-cooled condenser, 2a
...Outdoor fan motor, 2b...Outdoor fan, 3.
... Pressure reduction device, 4... Evaporator, 4a... Indoor fan motor, 4b... Indoor fan, 4C... Relay for indoor fan motor, 5... Control device, 6... Indoor temperature Detection thermistor. 7... Thermistor for outdoor temperature detection, 8... Phase angle control device, 9... Input circuit, 10... Microcomputer control circuit, 11... Driver, 12... Operation switch. Mine 1 map! Hayabusa 2 figures ¥ + 3 figures 1? ) Sabashi Akira & (・Riship F4餞;d <”Cr 草 5 feri-100102030-〇[[)′out fz*;il&<°cn

Claims (1)

[Claims] 1. In an air-cooled refrigeration cycle equipped with a function of controlling the rotation speed of an outdoor fan motor by an outdoor air temperature detection means, a means for detecting indoor air temperature is provided, and when the temperature is high, A low outdoor air cooling control method, characterized in that a control is added to correct the rotational speed control pattern of the outdoor fan motor to a high rotational side.