JPS5934259B2 - Air conditioner control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for an air conditioner that performs heating and cooling operations.

The control circuit provided in this type of air conditioner needs to operate the compressor motor when the room temperature is higher than the set temperature during cooling, and to operate the compressor motor when the room temperature is lower than the set temperature during heating.

For this reason, it was necessary to use a switch to change the mounting position of the temperature sensor in the bridge circuit, which includes the temperature sensor that detects room temperature and the variable resistor for temperature setting, and to install two comparison circuits with different characteristics. .

In addition, it is necessary to control the energization of the four-way valve, to display a display to distinguish between cooling and heating operations, and in cases where an auxiliary electric heater is provided, to prevent the electric heater from being energized during cooling.

For this reason, the control circuit requires complicated operation switches, the wiring becomes complicated, and the number of switches that change depending on the cooling/heating increases, making it more likely to malfunction and increasing costs.

Furthermore, the comfortable temperature differs between cooling and heating (
(4 to 5 degrees Celsius higher during cooling), a variable resistor for temperature setting that can be adjusted over a wide range is required, which increases the size and risks making the display difficult to read.

The present invention has been made in view of the above-mentioned facts, and aims to make the control circuit common for heating and cooling operations and improve reliability with a small number of switches and a simple circuit configuration, and furthermore, with simple operation, it is suitable for heating and cooling. The present invention provides a control circuit for an air conditioner that allows temperature adjustment.

An embodiment of the present invention will be described below based on the drawings.

The drawing shows the control circuit of the device. 1 is an AC power supply, rl is a normally open relay switch connected to one end of the AC power supply 1,
2 is connected to relay switch r1, and has three closing contacts, m and ■, a wind speed changeover switch, and 3 is a high-speed terminal H, which is a high-speed contact.

An indoor fan motor whose medium speed contact M is connected to the medium speed terminal m, the low speed terminal is connected to the low speed contact I, and the common terminal C is connected to the other end of the AC power supply 1, 4 and 5 are normally open relay switches r
A compressor motor and an outdoor fan motor are connected to the AC power source 1 via the AC power source 1.

6 is a four-way valve connected to AC power supply 1 via a normally open relay switch r3, 7 is a step-down transformer whose primary side is connected to both ends of AC power supply 1, and 8 is a step-down transformer whose input end is connected to AC power supply 1 via operating switch 9. rectifier connected to the secondary side of 7, 1
0 is a constant voltage circuit connected to the output end of the rectifier 8,
It consists of a smoothing capacitor 11, a resistor 12 and a constant voltage diode 13 connected in series in parallel with the smoothing capacitor 11.

A bus bar 15 is connected to a connection point 14 between the resistor 12 and a constant voltage diode 13, and a cooling/heating changeover switch 16 having a heating contact 161 and a cooling contact 162 is connected, and the other end of the constant voltage diode 13 is connected to the bus bar 11. has been done.

Also, 18°19 is the heating contact 161. These are control lines connected to the cooling contacts 162, respectively.

R1 is a relay switch r connected between bus bars 15 and 17
1 control relay, R3 is a control relay for relay switch r3 connected between control line 18 and bus bar 17, 20 is a cooling/warming display circuit, and resistor 21 and light emitting diode are connected in series between control line 19 and bus bar 17. A cooling indicator 22 consisting of
and a resistor 23 connected in series between the control line 18 and the bus bar 17.
and a heating indicator 24 made of a light emitting diode.

Reference numeral 25 is a comparison circuit, and a temperature sensor 26.25 is connected in series between the bus bars 15.17 and is an air conditioning load, which is a semiconductor thermosensitive element for detecting room temperature. Bridge circuit 31 consisting of variable resistor 27 and resistor 28 for temperature setting, and resistors 29 and 30
, a comparator 32 with a reference terminal 321° and a comparison terminal 322 connected to output points 311 and 312 of the bridge circuit 31, respectively, and an output terminal 323 of the comparator 32 and a reference terminal 321.
It consists of a feedback resistor 33 connected between the output point 311 and the control line 19, and a resistor 34 connected between the output point 311 and the control line 19.

Note that the power terminals 324 and 325 of the comparator 32 are connected to the busbars 15 and 17, respectively.

35 is a semiconductor logic circuit, and the output terminal 3 of the comparator 32
23 and a resistor 36.37 connected in series between the bus bar 17,
An NPN transistor 39 whose base is connected to the connection point 38 of the resistors 36 and 37 and whose emitter is connected to the bus bar 17, a diode 40 whose anode is connected to the collector of the transistor 39, an output terminal 323, and a connection point 41 of the resistor 36. and the cathode of the diode 40, the collector of the transistor 39 is connected to the control line 19 via the resistor 44, and the connection point 45 of the diode 42, 43 is connected to the control line 19 through the resistor 44. resistance 4
6 to a control line 18, and is configured such that a heating/cooling switching signal is supplied through control lines 18 and 19.

47 is a switching circuit, which includes a resistor 49.50 connected in series between a connection point 48 to which the output of the semiconductor logic circuit 35 is supplied and the bus bar 17, a base connected to the connection point 51 of the resistor 49.50, and a collector connected to the relay. It consists of an NPN transistor 52 whose emitter is connected to the bus 15 via the control relay R2 of the switch r2 and to the bus 17, respectively.

First, a situation in which the operation switch 9 is turned on and the heating/cooling changeover switch 16 is turned on to the heating contact 161 will be described.

A constant DC voltage is supplied between the bus 15, the control line 18, and the bus 17, and the control relay R11R3 is energized to close the relay switches rt and ra, respectively.

Therefore, the indoor fan motor 3 blows air at high speed, medium speed, or low speed depending on the ON position of the wind speed selector switch 2, and the four-way valve 6 is energized to set the refrigerant circuit (not shown) in a heating cycle. .

Further, in the cooling/heating display circuit 20, only the heating display 24 is energized.

For example, it emits red light to notify you that it is in a heating state.

On the other hand, the comparison circuit 25 calculates the temperature difference between the room temperature detected by the temperature sensor 26 and the set temperature set within a predetermined range by the variable resistor 27 at the output points 311 and 312 of the bridge circuit 31.
When the room temperature is lower than the set temperature, the voltage at the output point 311 is higher than the voltage at the output point 312, and the comparator 32 outputs a high (bi) voltage to the output terminal 323, and the room temperature is lower than the set temperature. is higher than the set temperature, output point 311
is lower than the voltage at output point 312, and comparator 32 provides a low voltage output at output terminal 323.

The semiconductor logic circuit 35 is supplied with a high (by) voltage from the control line 18, and when the output terminal 323 of the comparator 32 becomes a high voltage, the diode 43 becomes conductive in the forward direction and the connection point 48 becomes high ( bi) voltage.

Further, when the output terminal 323 of the comparator 32 becomes a low voltage, the diode 42 becomes conductive in the forward direction, and the voltage at the connection point 45 is reduced, so that the connection point 48 becomes a low voltage.

Namely. The semiconductor logic circuit 35 is used as the comparison circuit 25 during heating.
Since the same output appears at the connection point 48, when the room temperature is lower than the set temperature, the transistor 5 of the switching circuit 47
2 is conductive when the base bias is strong.

Control relay R2 is energized and operates compressor motor 4 and outdoor fan motor 5.

Moreover, when the room temperature exceeds the set temperature, the switching circuit 47
transistor 52 is cut off, control relay R2 is de-energized, and the compressor motor 4 and outdoor fan motor 5 are
to stop.

In this way, the air conditioner alternately performs heating operation and blowing operation.

Maintain room temperature near set temperature.

Next, the operation switch 9 is turned on, and the cooling/heating changeover switch 16 is turned on.
A situation in which the water is applied to the cooling contact 162 will be explained.

The difference between this cooling operation and heating operation is that a constant DC voltage is supplied between the control line 19 and the bus bar 17 instead of the control line 18, so the control relay R3 is first de-energized.
The four-way valve 6 is de-energized and the refrigerant circuit becomes a cooling cycle.

or,? /+ The room indicator 22 is energized and emits, for example, green light to notify that the air conditioner is in the cooling state, and the heating indicator 24 is turned off.

On the other hand, in the bridge circuit 31, the voltage at the output point 311 is increased by the current flowing from the control line 19 through the resistor 34, so the adjustable range of the set temperature set by the variable resistor 27 is a constant temperature from the heating time. It becomes a high predetermined range.

Further, the semiconductor logic circuit 35 is supplied with a high voltage from the control line 19, and when the output terminal 323 of the comparator 32 is at a low voltage, the transistor 39 is cut off and the diode 40
is in the forward direction, and the connection point 48 becomes a high voltage.

Conversely, when the output terminal 323 of the comparator 32 is at a high voltage, the transistor 39 conducts and lowers the collector voltage, the diode 40 becomes reverse biased and the node 48 becomes a low voltage.

In this way, in the semiconductor logic circuit 35, the inverted output of the comparison circuit 25 appears at the connection point 48.

Therefore, when the room temperature is higher than the set temperature, the switching circuit 4
Transistor 52 of switching circuit 47 is conductive, and control relay R2 is energized to operate the compressor motor 4 and outdoor fan motor 5. When the room temperature is lower than the set temperature, transistor 52 of switching circuit 47 is cut off and control relay R2 is energized. The compressor motor 4 and the outdoor fan motor 5 are turned off.

In this way, the air conditioner alternately performs cooling operation and ventilation operation to maintain the room temperature near the set temperature.

Although the explanation was omitted in the above embodiment, in the case where an electric heater for auxiliary air heating is provided, a control circuit for the electric heater that operates only during heating using the voltage signal of the control line 18 or 19 is added. In addition, it is possible to add various other control circuits that operate for either air conditioning or heating without increasing the number of changeover switches.

As described above, the present invention includes a temperature sensor for detecting an air conditioning load made of a semiconductor thermosensitive element, a bridge circuit made of a variable resistor for temperature setting, and a plurality of resistors, and a comparison circuit that compares the voltage at the output point of the bridge circuit. .

A semiconductor logic circuit that emits the same output as the comparison output of the comparison circuit when an air-conditioning/heating switching signal is supplied and outputs the same output as the comparison output of the comparison circuit in either cooling or heating operation, and outputs an inverted output of the comparison output in the other case; It consists of a switching circuit that starts and stops the compressor motor according to the logic output, so the temperature sensor can be installed in the bridge circuit by changing its position with a switch.

The compressor motor can be controlled using a common comparison circuit and switching circuit without increasing the number of comparison circuits, and temperature control suitable for heating and cooling can be performed.
By adding a semiconductor logic circuit made of inexpensive elements, it is possible to eliminate contact points and increase reliability.

In addition, the temperature setting ranges for cooling and heating can be shifted by a predetermined value by using the control line that supplies heating and cooling signals to the semiconductor logic circuit, allowing easy operation to set the temperature around the comfortable temperature for each. Therefore, there is no need to increase the size of the variable resistor or make the 0 display difficult to read.

Furthermore, this control line can be used to display the discrimination between air conditioning and heating, and to control the four-way valve, allowing various types of control for air conditioning and heating to be performed using a minimum number of changeover switches.

[Brief explanation of drawings]

The figure is an electrical circuit diagram showing one embodiment of the present invention. 18.19...control line, 25...comparison circuit. 26...Temperature sensor, 27...Variable resistor, 28-30...Resistor, 31...Bridge circuit, 311°312... Output point, 35
...Semiconductor logic circuit. 47...Switching circuit.

Claims (1)

[Scope of Claims] 1. A temperature sensor for detecting an air conditioning load made of a semiconductor thermosensitive element, a bridge circuit made of a variable resistor for temperature setting, and a plurality of resistors, and a comparison circuit that compares the voltage at the output point of the bridge circuit. and,? /+A semiconductor logic circuit which emits the same output as the comparison output of the comparison circuit when a heating switching signal is supplied and outputs the same output as the comparison output of the comparison circuit in either case of cooling or heating, and outputs an inverted output of the comparison output in the other case; A control circuit for an air conditioner including a switching circuit that starts and stops a compressor motor according to the logic output of a logic circuit. 2. A control line is provided to which a cooling signal and a heating signal as heating/cooling switching signals are separately supplied, and the control line is connected to the semiconductor logic circuit and the bridge circuit, and the temperature setting range of the variable resistor is set between cooling and heating. A control circuit for an air conditioner according to claim 1, which is configured differently in the following.