JPS5934255B2 - air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air conditioner equipped with a heat pump type refrigeration cycle mainly consisting of a compressor.

Generally, in this type of air conditioner, during heating operation,
To prevent the heating function from decreasing due to frost formation on the outdoor heat exchanger,
Defrosting operation is performed on the outdoor heat exchanger periodically or as needed.

Some of these air conditioners are designed to detect frost formation on the outdoor heat exchanger based on a change in the difference between the temperature of the indoor heat exchanger and the indoor temperature.

That is, this makes it possible to reliably detect the frosting state of the outdoor heat exchanger based on the temperature change of the indoor heat exchanger without being affected by the indoor temperature change.

However, in this case, there is a problem that the temperature of the indoor heat exchanger is also affected by the amount of indoor air circulation based on the operation of the indoor blower. For example, if the amount of indoor air circulation to the indoor heat exchanger is small, As a result, the temperature of the indoor heat exchanger rises, resulting in the inconvenience that the defrosting operation for the outdoor heat exchanger is not started even though it is necessary.

This invention was made in view of the above circumstances,
The purpose of this is to reliably detect the frosting state of the outdoor heat exchanger based on the temperature change of the indoor heat exchanger without being affected by the indoor temperature change or the amount of indoor air circulating to the indoor heat exchanger. The present invention provides a highly practical air conditioner that can perform an appropriate defrosting operation on an outdoor heat exchanger.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a heat pump type refrigeration cycle is constructed by sequentially communicating a compressor 1, a four-way switching valve 2, an outdoor heat exchanger 3, a capillary tube 4, and an indoor heat exchanger 5.

In this case, during the cooling operation, the refrigerant flows in the direction of the solid line arrow in the figure, and during the heating operation, the four-way switching valve 2 switches, so that the refrigerant flows in the direction of the broken line arrow in the figure.

The outdoor unit A is composed of the compressor 1, the four-way switching valve 2, the outdoor heat exchanger 3, the capillary tube 4, and the outdoor blower 6 for circulating outdoor air to the outdoor heat exchanger 3. There is.

Further, an indoor unit B is constituted by the indoor heat exchanger 5 and an indoor blower 7 for circulating indoor air to the indoor heat exchanger 5.

This indoor unit B has an operation control section (hereinafter referred to as microcomputer) that has a microcomputer (hereinafter abbreviated as microcomputer) programmed with a timer function, temperature control function, etc.
(not shown) is provided.

FIG. 2 shows the control circuit.

First, 10 is an operation control section provided in the indoor unit B.

This operation control section 10 includes a main control section 11 consisting of a microcomputer and its peripheral circuits, a blower switch 12 that responds to commands from the main control section 11, air volume adjustment switches 13, 14,
15, a heating operation switch 16, an operation switch 11, and an outdoor blower switch 18.

The main control unit 11 includes a temperature sensing element, such as a thermistor 20, which is attached to the indoor heat exchanger 5 and detects the temperature of the indoor heat exchanger 5, and a temperature sensing element, such as a thermistor 21, which detects the indoor temperature. each connected.

Further, the main control section 11 is supplied with driving command information from a so-called remote control type driving operation unit 22.

Therefore, the switch 12 is connected to one end of the AC power supply 30.
, 13, 14, and 15, one end of a blowing motor 71 of the indoor blower 7 is connected, and the other end of this blowing motor 71 is connected to the other end of the power source 30.

Further, one end of the four-way switching valve 2 is connected to one end of the power source 30 via the switch 16 and the terminal (2) on the terminal board 31 in series, and the other end of the four-way switching valve 2 is connected to the terminal (2) on the terminal board 31. The other end of the power supply 30 is connected to the other end of the power supply 30 through the power supply 30.

Further, at one end of the power supply 30, the above-mentioned switch 17° 18, a terminal ■ on the terminal board 31, and an outdoor thermoswitch 32 are connected.
One end of the blower motor 61 of the outdoor blower 6 is connected to the outdoor blower 6, and the other end of the blower motor 61 is connected to the other end of the power source 30 via the terminal (2).

Further, at the connection point between the switch 17 and the switch 18, a compressor for driving the compressor 1 is connected via a terminal (2) on the terminal board 31, an overload relay 33, a running capacitor RC1, a starting capacitor SC, and a starter 34. One end of the compressor motor 1 is connected to the compressor motor 1, and the other end of the compressor motor 1 is connected to the other end of the power source 30 via the terminal (2).

FIG. 3 shows the main circuits in the main control section 11.

That is, the DC voltage (2) is supplied to the series body of the thermistor 20, temperature correction circuit 40, and resistor 50.

Thus, a voltage that changes depending on the temperature of the indoor heat exchanger 5 is obtained at the connection point a between the temperature correction circuit 40 and the resistor 50.

Here, the temperature correction circuit 40 includes the switch 13,
Switches 131 and 140 that respond to signals 14 and 15, respectively.
．． 15, and resistors 41, 42, 43 (resistance 41 <resistance 42 <resistance 43).
1, that is, the voltage at the connection point a is changed in accordance with the circulation amount of indoor air with respect to the indoor heat exchanger 5.

Then, the voltage at connection point a is input resistor R1, feedback resistor R2
and a negative feedback amplifier circuit 52 consisting of an operational amplifier circuit 51, and the output of this negative feedback amplifier circuit 52 is supplied to an input resistor R.
3. The signal is supplied to the inverting input terminal (-) of a negative feedback differential amplifier circuit 54 consisting of a feedback resistor R4 and an operational amplifier 53.

- The voltage at the connection point between the thermistor 21 and the resistor 60 is determined by the input resistor R5, the feedback resistor R6 and the operational amplifier 61.
The output of the negative feedback amplifier circuit 62 is supplied to the non-inverting input terminal (+) of the differential amplifier circuit 54.

In this way, a voltage corresponding to the difference between the corrected temperature of the indoor heat exchanger 5 and the indoor temperature can be obtained from the differential amplifier circuit 54.

Then, the output of this differential amplifier circuit 54 is transmitted to a comparator circuit 70.
The signal is supplied to the inverting input terminal (-) of the circuit, and is also supplied to the peak hold circuit 71.

This peak hold circuit 71 is connected to the differential amplifier circuit 54 described above.
It outputs a voltage corresponding to the maximum value of the output voltage.

Therefore, the output of the peak hold circuit 11 is supplied to a series body of the resistor Ra and the resistor Rb, and the voltage obtained at the connection point C between the resistor Ra and the resistor Rb is the voltage of the comparator circuit 10. It is designed to be supplied to the non-inverting input terminal (+).

In this way, the comparator circuit 70 outputs a logic "1" signal when the voltage output from the differential amplifier circuit 54 becomes smaller than the voltage at the connection point C.

In other words, when the voltage corresponding to the difference between the corrected temperature of the indoor heat exchanger 5 and the indoor temperature drops by a certain value from its maximum value,
The comparator circuit 10 outputs a logic 11'' signal.

The output of this comparison circuit 10 is supplied to one input terminal of a gate circuit, for example, an AND circuit 12.

Further, the output of the Quimsafe circuit 13 is supplied to the input terminal of the other force of the AND circuit T2.

This time safe circuit 13 outputs a logic 11" signal after a certain period of time after heating operation is started, and is intended to prevent malfunction of operation control in an unstable state at the start of operation.

Therefore, when the time-safe circuit 13 outputs the logic 11" signal, that is, when the heating operation has already entered a stable state, when the comparator circuit 70 outputs the logic "'l" signal, the AND circuit 72 A logic 11" signal is output from the logic 11" signal.

Here, the logic "1" signal output from the AND circuit T2 serves as a defrosting start signal and is supplied to the microcomputer.

Next, the operation in the above configuration will be explained.

This case will be explained with reference to FIGS. 4a, b, c, d, and e.

Now, when the heating operation is set for the operation control section 10, the switches 12, 1 are activated based on the command from the main IIJt1 section 11.
When 6, 17, and 18 are turned on, the blower motor 71, the four-way switching valve 2, the blower motor 71, and the compressor motor 11 operate, respectively.

Then, the refrigerant discharged from the compressor 1 is transferred to the four-way switching valve 2.
Due to this switching, the heat flows sequentially to the indoor heat exchanger 5, capillary tube 4, and outdoor heat exchanger 3, forming a heating cycle.

Furthermore, outdoor air is circulated to the outdoor heat exchanger 3 by the operation of the outdoor blower 6, and heat is pumped up from the outdoor air by the evaporation action in the outdoor heat exchanger 3.

In addition, indoor air is circulated to the indoor heat exchanger 5 by the operation of the indoor blower I, and the heat pumped up by the outdoor heat exchanger 3 is released to the indoor air by the condensation action in the indoor heat exchanger 5. .

In other words, heating operation will be performed. In this manner, when the heating operation is performed, water droplets adhering to the surface of the outdoor heat exchanger 3 gradually turn into frost as the temperature of the outdoor heat exchanger 3 decreases.

At this time, the temperature of the indoor heat exchanger 5 gradually decreases as frost formation progresses in the outdoor heat exchanger 3.

Thus, the temperature of the indoor heat exchanger 5 is detected by the thermistor 20, and the voltage at the connection point a is determined according to the change in the resistance value of the thermistor 20.

By the way, in this case, assuming that the switch 13 is turned on by the command from the main control unit 11, the blower motor 1
, are operating at a low speed, so that the amount of indoor air circulated to the indoor heat exchanger 5 is smaller than when the blower motor 71 is operating at a high speed H.

Therefore, in conjunction with turning on the switch 13, the temperature correction circuit 4
The switch 13 at 0 is on, and the resistor 42 is connected to the thermistor 20.

That is, this uses the temperature change of the indoor heat exchanger 5 when the blower motor 7□ is operating at high speed H as the reference for detecting the frosting state of the outdoor heat exchanger 3, and the air volume decreases. The temperature rise of the indoor heat exchanger 5 due to the connection point a
This is to correct the voltage increase.

Therefore, a voltage J corresponding to the difference between the corrected temperature Tc of the indoor heat exchanger 5 and the indoor temperature Ta is output from the differential amplifier circuit 54 and supplied to the comparison circuit 70 and the peak hold circuit 11.

In this way, the voltage K corresponding to the maximum value of the voltage J is output from the peak hold circuit 11, which causes the connection path TO
supplied to

Thus, the comparator circuit TO outputs a logic 11" signal when

In this case, since a certain period of time has passed since the heating operation was started, the output of the time safe circuit 13 has already become a logic 11" signal.

Therefore, the defrosting start signal (logic 'X1
“signal) is output and supplied to the microcontroller.

In this way, the switch 16.
18 is turned off, and the four-way switching valve 2 and the blower motor 6 are turned off.
Each operation of 1 stops.

Then, the operation of the four-way switching valve 2 is stopped, so that the heating cycle becomes a reverse cycle, and the operation of the outdoor hot air fan 6 is also stopped, and the defrosting operation for the outdoor heat exchanger 3 is performed.

When the time required for the defrosting operation has elapsed due to the timer function of the microcomputer, the switches 16 and 1B are turned on again, and the heating operation is restarted.

Note that when the output of the comparison circuit 10 becomes a logic "l" signal, the output of the peak hold circuit 11 is reset,
This is preparation for the next frost condition detection.

In other words, the corrected temperature Tc of the indoor heat exchanger 5 and the indoor temperature Ta
(Tc-Ta) is the maximum value (Tc-Ta)m
A defrosting start signal is obtained when the temperature drops by a certain value from ax, and this allows detection of the frosting state based on the temperature change of the indoor heat exchanger 5 to detect the indoor temperature change and the indoor heat exchanger 5. This can be done reliably without being affected by the amount of indoor air circulation.

Therefore, the outdoor heat exchanger 3 can be properly defrosted.

As described above, according to the present invention, the temperature of the indoor heat exchanger is corrected according to the amount of indoor air circulation to the indoor heat exchanger, and the corrected temperature of the indoor heat exchanger and the indoor Since the frosting state of the outdoor heat exchanger is detected based on the change in temperature, the frosting state of the outdoor heat exchanger can be detected based on the temperature change of the indoor heat exchanger. Provides a highly practical air conditioner that can perform defrosting operations reliably without being affected by the amount of indoor air circulating to the heat exchanger, thereby performing appropriate defrosting operations for outdoor heat exchangers. can.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram of a heat pump refrigeration cycle, FIG. 2 is a diagram of a control circuit, and FIG. 3 is a diagram of a main circuit in the main control section. Block diagram, Figure 4 a, b. c, d, and e are diagrams for explaining the operations, respectively. 1... Compressor, 2... Four-way switching valve, 3
...Outdoor heat exchanger, 4...Capillary tube, 5...Indoor heat exchanger, 20...
...First temperature sensing element (thermistor for indoor heat exchanger temperature detection), 21...Second temperature sensing element (thermistor for indoor temperature detection), 40...Temperature correction circuit .

Claims (1)

[Claims] 1. An air conditioner equipped with a heat pump refrigeration cycle in which a compressor, a four-way switching valve, an outdoor heat exchanger, a capillary tube, an indoor heat exchanger, etc. are connected in sequence, and capable of performing heating operation by switching the four-way switching valve. In the machine, a first temperature-sensing element detects the temperature of the indoor heat exchanger, a second temperature-sensing element detects the indoor temperature, and the first temperature-sensing element detects the temperature in conjunction with the air volume adjusting means of the indoor blower. A circuit for correcting the temperature, and means for controlling the defrosting operation of the outdoor heat exchanger based on the temperature of the indoor heat exchanger corrected by the circuit and the temperature detected by the second temperature sensing element. An air conditioner featuring: