JPS6089634A - Control device for air conditioner - Google Patents

Abstract

PURPOSE:To prevent a frosting at an indoor heat exchanger and eliminate an unti-freezing thermistor by a method wherein an efficient control over a frequency is performed under a relation between a room temperature and a predetermined temperature to vary the number of rotation of a compressor. CONSTITUTION:An outdoor heat exchanger 2 is arranged at one side of a compressor 1 of which number of rotation is variable, an indoor heat exchanger 3 is arranged at the outdoor heat exchanger 2, the indoor heat exchanger 3 is arranged at the other side of the compressor 1 to constitute a heating medium circulation circuit 4 in an air conditioner. A room temperature sensor element TH1 is arranged so as to detect a room temperature, and a control electric circuit X for use in controlling the number of rotation of the compressor 1 with an electrical sensing signal of the sensor element TH1 during a dehumidifying operation is arranged. A microcomputer IC1 in the control electric circuit X judges a region in a thermo-line where a room temperature is set in reference to input data of set temperature and input data of a difference in temperature between a room temperature and a predetermined temperature, and then an output is produced at the pulse width modified wave generating circuit IC4.

Description

[Detailed Description of the Invention] Technical Field> The present invention provides an air conditioner equipped with an inverter circuit,
It mainly relates to a control device that controls the rotation speed of a compressor based on room temperature to prevent freezing of an indoor heat exchanger.

<Prior Art> In general, in an air conditioner, if the room temperature drops during dehumidification operation, frost will form on the indoor heat exchanger and the heat exchange rate will decrease, so it is necessary to stop the dehumidification operation.

Conventionally, as a detection means for stopping the compressor, an antifreeze thermistor was installed in the indoor heat exchanger (=1 digit), and when the pipe temperature drops below a certain temperature (for example, -10°C),
The compressor was stopped to prevent freezing.

<Confession> In view of the above, the present invention provides a control device for an air conditioner that can omit the antifreeze thermistor by efficiently controlling the frequency based on the relationship between the room temperature and the set temperature, and changing the rotational speed of compression. intended to provide.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.
This has an outdoor heat exchanger 2 on one side of the variable rotation speed compressor 1.
is piped, an indoor heat exchanger 3 is piped to the outdoor heat exchanger 2, and the indoor heat exchanger 3 is piped to the other side of the compressor 1 to form a heat medium circulation circuit 4. In,
a control electric circuit
is provided.

This heat medium circulation circuit 4 has a conventionally well-known so-called heat pump type configuration, and during cooling operation, the heat medium discharged from the compressor 1 is sent to the outdoor heat exchanger 2 and is sent to the outdoor air blower t1.
The air is cooled and condensed by the air blower 5, and after being reduced in pressure by the pressure reducer 6, it enters the indoor heat exchanger 3 where it evaporates and performs a cooling action. On the other hand, during heating operation, by switching the four-way valve 8, the heat medium in the compressor 1 is transferred from the indoor heat exchanger 3 → pressure reducer 6 → outdoor heat exchanger 2 →
It flows with compressed rock 1 and performs heating operation.

FIG. 2 shows the control electric circuit X of the present invention, in which 9 is a DC power supply terminal (DC12V), and ICI is a general one-chip microcomputer (hereinafter referred to as microcomputer), which internally has a program ROM, data RAM, It has ALU etc.
It sequentially reads out the instructions in the program ROM in synchronization with the basic clock, performs analysis, reads data from the input port, and outputs data from the output port.

IC2 is a comparator, which is a room temperature sensing element (negative characteristic thermistor)
THl is connected to the positive terminal side of the comparator IC2. IC3 is a buffer group, 10 is a D/A conversion circuit section, and its output section 1()a is connected to the negative terminal side of comparator IC2, and an analog signal of the set temperature is outputted to comparator IC2.

Furthermore, from the relationship between the room temperature and the set temperature, as shown in Figure 3, three types of thermolines A, B, and C are set to separate the regions, and it is determined to which region the room temperature belongs.
An experimental result was obtained that frost formation on the indoor heat exchanger 3 can be prevented by controlling the rotation speed of the indoor heat exchanger 3. Therefore, the microcomputer ICI sets the thermolines A, B, and C, and uses the input data of the set temperature and the input data of the temperature difference between the room temperature and the set temperature from the comparator IC2 to set the room temperature of the thermolines A to C. It is determined which region it is in and outputs it to the pulse width modulation waveform generation circuit IC4. In this pulse width modulation waveform generation circuit IC4, the frequency is 30 to 90H.
For example, z is decomposed into 4 bits, and 40 bits are used for A-line and above.
Hz output, 30 Hz output between A and 8947, 30 Hz output for 3 minutes and 3 minute OFF output between B and C lines, and OFF output below C line.

IC5 is a drive circuit for power transistors Q1 to Q6,
11 is an inverter circuit, which is a DC power supply (DC280
V) 12i: Yo l) P sent from I dynamic circuit engineer C5
The power transistors (01 to Q6) are switched according to a WM (pulse width modulation) signal to create three-phase alternating current and supply it to the compressor 1. In addition, the output ports x1 to *6 of the microcomputer CI in Figure 2 are buffer group ICs.
3 input ports x1 to x6.

Next, the specific operation of the present invention will be explained based on FIGS. 3 and 4. During the cooling and dehumidifying operation, the room temperature RT is sensed by the room temperature sensing element THI, and is converted into A/D by the microcomputer ICI.
It is determined in which zone of the A-C line the room temperature is located and output to the pulse width modulation waveform generation circuit IC4. In this generation circuit IC4, as shown in FIG.
Hz output, 30Hz output between A-8947, B-C
Between the lines, an OFF output signal is output for 3 minutes with a 30 Hz output for 3 minutes, and an OFF output signal is output for the C line and below, respectively, to the power transistor drive circuit IC5. In response to the output signal from the PWM signal generation circuit IC4, the inverter circuit 11 switches the 280V DC power supply]2 to the power transistors Q1 to Q6 according to the PWM signal to create a three-phase alternating current, thereby controlling the rotation speed of the compressor 1. Control.

Also, as shown in Figure 3, even if the set temperature is below 22℃,
The A line remains at 23.5°C, the B line remains at 22°C,
Pressure & itE below 22℃! ] is controlled to prevent continuous operation. By controlling as described above, the antifreeze thermistor can be omitted.

<Effects> As is clear from the above description, the present invention provides an outdoor heat exchanger that is piped to one side of a variable rotation speed compressor, an indoor heat exchanger that is piped to the outdoor heat exchanger, and the indoor heat exchanger. In an air conditioner in which a heat medium circulation circuit is configured by piping an exchanger to the other side of the compressor, a room temperature sensing element for sensing the indoor temperature is provided, and the electrical voltage of the sensing element is A control electric circuit is provided to control the rotational speed of the compressor based on a detection signal.

Therefore, according to the present invention, since the rotation speed of the compressor can be efficiently controlled during dehumidification operation based on the relationship between the room temperature and the set temperature, frost formation on the indoor heat exchanger can be prevented, and the antifreeze thermistor can be omitted. It has such excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an air conditioner showing an embodiment of the present invention;
FIG. 2 is a control electric circuit diagram, FIG. 3 is a diagram showing the relationship between the control thermoline and the room temperature and set temperature, and FIG. 4 is a control flowchart. 1: Compressor, 2: Outdoor heat exchanger, 3: Indoor heat exchanger, 4
: heat medium circulation circuit, THI: room temperature sensing element, X: control electric circuit. Applicant Sharp Corporation Agent Tsunehisa Nakamura

Claims (1)

[Claims] An outdoor heat exchanger is piped to one side of the compressor with variable rotation speed.
In an air conditioner in which an indoor heat exchanger is piped to the outdoor heat exchanger and the indoor heat exchanger is piped to the other side of the compressor to form a heat medium circulation circuit, for sensing indoor temperature. An air conditioner comprising: a room temperature sensing element; and a control electric circuit that controls the rotation speed of the compressor based on an electrical detection signal from the sensing element during dehumidification operation.