JPS58115235A - Control circuit of air conditioner - Google Patents

Abstract

PURPOSE:To shorten the defrosting operation of the titled air conditioner and accelerate the rise-up thereof after defrosting by setting the rotational speed of an electrically-driven compressor to a value higher than the set rotational speed computed on the basis of the room temperature and the room temperature set value during the defrosting operation and within a predetermined period of time after or before that at the time of heating. CONSTITUTION:The coolant discharged from the compressor during the heating operation is circulated in the sequence of four-way valve 1a, indoor heat exchanger 5, voltage reducing device 4 and outdoor heat exchanger 3. During the heating operation, when an AND condition is established between a signal from a defrosting timer contained in a microcomputer 8 and a signal from a defrosting thermostat 19 detecting the temperature of the outdoor heat exchanger 3, the rotational speed of the compressor motor 2 is increased up to the maximum rotational speed while continuing the heating operation by the operation of the microcomputer 8 and the inverter unit 14. After the motor 2 reaches the maximum rotational speed, the four-way valve 1a is changed over, to shift the freezing cycle to the defrosting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for an air conditioner having a refrigerant compression cycle, and particularly to a control circuit for a variable capacity air conditioner controlled by an inverter.

Electric compressors, refrigerant flow switching valves, outdoor heat exchangers, pressure reducers,
An air conditioner is equipped with a refrigerant compression cycle in which indoor heat exchangers are sequentially connected, and the air conditioner has the same blowing ratio for the outdoor heat exchanger and the indoor heat exchanger, respectively, and the electric compressor is supplied with power. There is an inverter control system that controls the frequency and voltage of It is effective to keep it small. However, if the electric compressor is operated at a low rotation speed during heating operation and frost forms on the outdoor heat exchanger, it will enter defrost operation and defrost at its main rotation speed. During operation, there was a problem in that the defrosting time was long due to the low rotational speed.

In view of the above, the present invention controls the rotation speed of the electric IT and compressor during and before and after defrosting operation, shortens the time of defrosting operation, suppresses the decrease in room temperature as much as possible, and furthermore, The present invention aims to provide a control circuit that allows room temperature to rise quickly.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment.2- In FIG. 1, 1 is a compressor, 2 is a compressor! The compressor motor drives the compressor motor 1, which constitutes 1) an electric compressor. 3 is an outdoor heat exchanger, 4 is a pressure reducer such as a capillary tube, 5 is an indoor heat exchanger, and 1a is a four-way valve as an example of a switching valve that switches the flow of refrigerant. They are connected in a circuit to form a refrigerant compression cycle. In this refrigerant compression cycle, heating operation is performed when the four-way valve 1a is on, and cooling operation is performed when it is off. 6 is an outdoor blower provided corresponding to the outdoor heat exchanger 3, and 7 is an indoor blower provided corresponding to the indoor heat exchanger 5.

8 is a general one-chip microcomputer (hereinafter referred to as microcomputer), which has input terminals IN1 to 1N5 and output terminals 0UT1 to 0UT6, and has a program ROM and data RAM inside.

It has an A1-IJ and a defrost timer (software timer), and is driven by a reference clock oscillation section 9. 10 is a thermistor for detecting room temperature, and 11 is an A/D converter, which converts the room temperature 3- detected by the thermistor 10 into a digital value and inputs it to the input terminal N1 of the microcomputer 8. 12 is a variable resistor for setting the room temperature, 13 is an A/D
A converter converts the internal value set by the variable resistor 12 into a digital value and inputs it to the input terminal IN2 of the microcomputer 8.

Reference numeral 14 denotes an inverter section, in which the AC power source input from the power source terminals 15 and 15' is rectified by diodes D1 to D4, smoothed by a capacitor C4°, and then transferred to a transistor Tr1.
．． Trl', W phase, transistor Tr2. At Tr2'\
l phase, transistor Tr3. The three phases of the U phase are each phase-controlled by Tr3' to generate three-phase alternating current, and the three-phase compressor motor 2 is operated. Reference numeral 16 denotes a run/stop switch, which is connected to the input terminal TN4 of the microcomputer 8. 17 is the four-way valve 1
This is a cooling/heating selector switch for switching between a and a, and is connected to the input terminal IN3 of the microcomputer 8.

−, the microcomputer 8 is connected from the input terminal INI to the room temperature, and the input terminal T
The chamber W setting values are read from N2, and signals for controlling the frequency and voltage of the two-phase voltages U, V, and W, which are energized to the compressor motor 2 via the inverter section 14, are sent from the output terminals 0UT1 to 0UT3. The output 4- is used to control the rotational speed of the compressor motor 2 via the transistor drive circuit 18, thereby making the cooling capacity variable. 1 is a thermistor for frost detection, 2
0 is an A/D converter that converts the room temperature detected by the thermistor 19 into a digital value and inputs it to the input terminal INS of the microcomputer 8. The microcomputer 8 outputs from the output terminals 01JT1 to 0LlT3 a signal that controls the frequency and voltage of the two-phase voltages U, V, and W that are energized to the compressor motor 2, and a signal that switches the four-way valve 1a. Output. In this way, the microcomputer 8 and the inverter section 14 constitute a so-called pulse width modulation type inverter control section. Note that the capacitors c, , c, of the inverter section 14
'~c,,c3' are transistors Trl, Tri'
-Tr3. This is to prevent Tr3' from malfunctioning due to noise. Also, resistor R1 and capacitor C,
, R4 and C, , R2 and C5° R1 and C, , R, and C6,
Each RC series circuit consisting of R, and C9 is connected to a transistor/Tr by a back electromotive voltage after the compressor motor 2 is turned off.
i, Tri' to Tr3°5- This is a discharge circuit to prevent damage to Tr3'. My fun output terminal ○UT4, 0UT5. ○The control outputs of the outdoor blower 6, the indoor blower 7, and the four-way valve 1a are generated in the UT 6, respectively.

In the above configuration, when the compressor 1 is driven by the compressor motor 2 during cooling operation, the refrigerant compressed by the compressor 1 is
After being cooled and condensed in the outdoor heat exchanger 3 by the air blown by the outdoor blower 6, the pressure is reduced in the pressure reducer 4, evaporated in the indoor heat exchanger 5 to perform a cooling effect, and the indoor blower 7 blows air to cool the room. do. On the other hand, during heating operation, the four-way valve 1a is switched to the on state as shown in Figure 2, and the flow of refrigerant is reversed so that the compressor 1 → four-way valve 1a → indoor heat exchanger 5 →) inertia unit 4 → outdoor heat The air flows through the exchanger 3 and air is blown by the indoor blower 7 to perform heating operation.

Next, the defrosting operation of the outdoor heat exchanger during heating will be explained based on the time chart of FIG. 3. In FIG. 3, the defrost signals include a signal from a defrost timer that is installed in the microcomputer 8 and operates at a certain time period, and a temperature from a defrost thermostat 6-stat that detects the temperature of the outdoor heat exchanger 3. This is a signal output based on the data signal. For example, if the defrost timer is set to 50 minutes with a 60 minute cycle.
It operates to perform heating operation for 1 minute and defrosting operation for 10 minutes, and the defrosting thermostat is set to 1 (1
Assuming that the defrosting end signal is output at "C or higher" and the frosting signal is output at -2.5°C or below, the defrosting signal is the AND condition of the defrosting timer and the defrosting thermostat. Defrosting is started under the OR condition, and defrosting is ended under the OR condition. That is, the defrosting time ends when the defrosting thermostat reaches 10'C or higher, or when 10 minutes have elapsed, and the heating operation returns.

For example, when the defrosting timer reaches point A, the microcomputer 8 and inverter section 14 operate to increase the rotation speed of the compressor motor 2 to the maximum rotation speed while continuing the heating operation. And A
At point B, after T1 time has elapsed from point B, a defrosting signal for switching the four-way valve 1a to the OFF state (cooling side) is output, the four-way valve 1a is switched, and defrosting operation begins. During the defrosting operation, the compressor motor 2 is rotated at the maximum rotation speed. At the end of the defrosting operation, when the defrosting end signal is input at point 0, the microcomputer 8 works in the same way as above, outputting a signal to switch the four-way valve 1a from the cooling side to the heating side, and turning the four-way valve 1a on. Switch. However, the compressor motor 2 then operates at the maximum rotation speed for a time T2, returns to the normal set rotation speed at point D, and continues operating. Note that after point E in Figure 3, the defrost signal is not output because the defrost thermostat is 10'C or higher when the defrost timer is activated, so the defrost signal is not output at point E, but instead of defrosting. The compressor continues to operate at maximum rotation speed for T3 hours, and then returns to the set rotation speed.

This control operation is explained using the flowchart in Fig. 5.
First, it is determined by 7 lag F (maximum rotation speed after defrosting) whether it is between C-D immediately after defrosting, and if it is not C-D, it branches to NO, and then the defrosting flag is set. (Set during defrosting) to determine whether defrosting is in progress, and if NO, determine whether defrosting time is before the defrosting time (after point A in FIG. 3).

If the answer is NO, the compressor goes straight to OUT, and if the answer is YES, the rotation speed of the compressor is increased one step at a time to the maximum rotation speed in preparation for defrosting. Next, wait until the defrost timer reaches point B or higher, and when it reaches point B or higher, the defrost thermostat will turn on.
It is determined whether the temperature is below 2.5°C, and if it is below, the defrost flag is set and the process goes to OUT. Next, return to IN, and if YES in "Set defrost flag", switch the four-way valve to the cooling side, turn off the indoor and outdoor blowers, and perform defrosting operation. Then, the defrost timer reaches 0 points, but wait until the defrost thermostat reaches 10℃ or higher, finish defrosting at either end, reset the defrost flag, and switch the four-way valve to the heating side. Turn on the indoor and outdoor blowers, finish defrosting operation, set 7 lag F, and exit to OUT.

Next, return to TN and select YES for "Set flag F".
If it branches to , the rotation speed of the compressor will be lowered one step at a time to the set rotation speed. Then, when the set rotation speed is reached, the 7-lag F is reset, the defrost timer is cleared, and the engine exits to OUT.

Here, the reason for operating at maximum rotation speed between A-*B and C→D is established based on Figure 4. Figure 4 (a) shows the case where operation is performed at maximum rotation speed only during defrosting operation. Figure 4 (1)) shows the room temperature changes when A-B and C-D are also operated at the maximum rotational speed as in this example. . In the case of (a), the room temperature starts to drop gradually from the start of the defrosting operation, reaches its lowest point immediately after the end of defrosting (1), and returns to the original room temperature. However, in the case of (b) showing this embodiment, the room temperature rises a little before defrosting, that is, between A-H in Fig. 3, and then defrosting begins and the lower part starts 1), immediately after the end of defrosting. is the lowest, and then decreases during heating operation, so the absolute value of the lowest room temperature is higher than in case (a), and the difference from (,) is expressed as J. Furthermore, the rise in room temperature at the end of defrosting is 1]
At times T4 and T5, T4. > T 5,
In this example, the room temperature returns to the original temperature more quickly.

In addition, in the time chart of FIG. 3, the rotation speed of A-D is set to the maximum, but in the present invention, even if it is not the maximum, the maximum rotation speed τ
The number of rotations may be close to 1. Further, in the present invention, in addition to the control operation as in the above embodiment, a control operation as shown in the flowchart of FIG. 6 may be used. That is, enter from IN, check the defrost flag (set during defrosting), if No, then set the frosting signal to 'I'l + constant 10-, and if it is off (no frosting), go directly to OtJ T. If it is on (frosting), increase the rotation speed of the compressor one step at a time until it reaches the maximum rotation speed. Thereafter, it is determined whether T1 time has elapsed, and if it has, the defrosting flag is set, the four-way valve is switched to the cooling side, and the indoor and outdoor blowers are turned off to perform defrosting operation. Next, if it goes into IN and branches to YES based on the defrost flag judgment, it determines whether the frosting signal is off or not, and if it is frosted, it goes directly to OUT, and if there is no frosting (defrosting is finished), it goes to YES. 1. Switch the four-way valve to the heating side, turn on the indoor and outdoor blowers, end the defrosting operation, and start the heating operation. After 12 hours have elapsed, the compressor rotational speed is lowered one step at a time, and when the set rotational speed is reached, the defrost flag is reset to 0 and sent to IT.

(1) As is clear from this explanation, the present invention sets the rotation speed of the electric compressor to a setting calculated based on the room temperature and the room temperature set value during the defrosting operation during heating and during a certain period of time before and after the defrosting operation. Since the rotation speed is set to be higher than 1), according to the present invention, the defrosting operation time can be shortened and the drop in room temperature can be suppressed as much as possible, and the room temperature after defrosting can be It is also possible to start up quickly.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the switching state of a four-way valve, FIG. 3 is a time chart of the control circuit, and FIG. 4 (a) (+ )) is a time chart in comparison with a conventional control circuit, FIG. 5 is a flowchart, and FIG. 6 is a flowchart showing another embodiment of the present invention. 1: Compressor, 1a: Four-way valve, 2: Compressor motor, 3: Outdoor heat exchanger, 4: I intimidator, 5: Indoor heat exchanger, 6: Outdoor blower, 72 Indoor blower, 8: Micro pump User, 14: Inverter section, 16: Run/stop switch, 1
7: Cooling/heating selector switch. Applicant Sharp Corporation Companywide Agent Tsunehisa Nakamura 12-162

Claims (1)

[Claims] Electric compressors, refrigerant flow switching valves, outdoor heat exchangers, pressure reducers,
It is equipped with a refrigerant compression cycle in which indoor heat exchangers are sequentially connected, a blower is provided in each of the outdoor heat exchanger and indoor heat exchanger, and an inverter control unit is provided to control the frequency and voltage of the power supply to the electric compressor. In the control circuit of the air conditioner, during the defrosting operation during heating and for a certain period of time before and after, the rotation speed of the electric compressor is set higher than the set rotation speed calculated based on the room temperature and the room temperature setting value. A control circuit for an air conditioner, characterized in that it is configured to.