JPH0745954B2 - Air conditioner control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device, particularly a safety device, of an air conditioner that heats a heat medium by combustion.

2. Description of the Related Art A heat pump air conditioner has been generally put into practical use as a device for heating and cooling by connecting indoor and outdoor units with a refrigerant pipe. However, in the case of the heat pump air conditioner, there is a problem that the capacity is reduced at the time of low outside air temperature where heating is required most, and high-temperature strong wind cannot be blown out.

To solve such problems, for example, Japanese Patent Application No. 61-
There is a system shown in 245729 (Japanese Patent Laid-Open No. 63-99467). That is, in FIG. 6, during the heating operation,
First, when heating is started, the first solenoid valve 1, the second solenoid valve 2, and the opening / closing valve 3 are closed, and the third solenoid valve 4 and the fourth solenoid valve 5 are opened to operate the compressor 6. Since the refrigerant path is sealed by the action of the first solenoid valve 1 and the second check valve 7, the refrigerant distributed in the outdoor refrigerant condenser 8, the accumulator 9 and the various refrigerant pipes connecting them is When the suction pump is down during the operation of the compressor 6, all the refrigerant is pumped up to the refrigerant heater 11 via the first check valve 10. After this pump down operation, the compressor 6 is stopped and the fourth solenoid valve 5
And a burner (not shown) is ignited and heating operation is started. The heat medium pumped up to the refrigerant heater 11 is heated by the burner and evaporated to increase the evaporation pressure, and the evaporated high-temperature and high-pressure refrigerant gas flows from the refrigerant heater 11 to the third solenoid valve 4 and from the refrigerant pipe 12 to the room. It is pumped to the heat exchanger 13. At this time, when the indoor fan 14 is operated, the high-temperature and high-pressure refrigerant gas radiates heat and is heated to condense and liquefy. The refrigerant liquid flows from the refrigerant pipe 15 through the third check valve 16 into the liquid receiver 17 to be received. When the liquid level of the liquid received reaches a certain level, the on-off valve 3 is closed and the evaporation pressure is set to the liquid receiver.
Since it is added to the refrigerant heater 17 and has the same static pressure as that of the refrigerant heater 11, the refrigerant liquid in the liquid receiver 17 flows into the refrigerant heater 11 due to the head differential pressure of the liquid receiver 17. After the liquid level of the liquid receiver 17 is lowered, the on-off valve 3 is closed to return to the initial state.

As described above, during the heating operation, the refrigerant is heated by the burner and the heat is transferred to the indoor unit, so it is possible to blow out a high-temperature strong wind even at a low outdoor temperature. If heat exchange cannot be performed sufficiently due to a system abnormality such as dust clogging of the machine, a dangerous situation such as rupture of piping due to pressure increase will occur. Therefore, a pressure switch is attached to the refrigerant pipe as a safety device, and when the pressure rises, the operation of the pressure switch stops the operation of the equipment to ensure safety and to prevent the pressure from rising to the operating point of the pressure switch. There was a means to stop the combustion and suppress the rise in pressure when a temperature sensor was attached to the temperature sensor.

However, in the above-mentioned means, since the rise of the pipe pressure is detected by approximating the rise of the temperature and the combustion is stopped, even if there is a close relationship between the pressure and the temperature, there is a variation in the temperature sensor. There is a large variation in the pressure approximated by the detected temperature due to variations in the mounting location and mounting method of the temperature sensor,
There is a risk that the pressure rise will not be detected due to the temperature and the pressure will rise to the pressure switch operating point.Also, if the design is such that the temperature is detected accurately before the pressure switch is activated in consideration of variations, the temperature of the refrigerant will be low. However, there was a problem that combustion could not be stopped and sufficient heating operation could not be performed.

The present invention solves such a conventional problem, and corrects the variation that occurs when the pipe pressure is approximated and detected by the pipe temperature, and surely stops combustion before the pressure rises to ensure safety. However, the purpose is to exert sufficient heating capacity.

Means for Solving the Problems To solve the above problems, the control device for an air conditioner of the present invention is a heat source that heats a heat medium by combustion, and a heat exchanger that heats air by heat exchange with the heat medium. , Heat transfer means for circulating the heat medium between the heat source and the heat exchanger, temperature detecting means for detecting the temperature of the heat medium flowing into the heat exchanger, and combustion due to pressure increase of the heat medium to stop combustion Pressure switch and a control unit for controlling the heat source, the control unit sets a temperature lower by a predetermined value than the temperature detected by the temperature detection unit, and detects the temperature after the pressure switch returns again. When the temperature detected by the means exceeds the set temperature of the setting unit, the stop unit stops the combustion, the counter that counts the number of times the pressure switch operates, and the heat source is connected when the number of times the counter operates exceeds a predetermined number. The configuration has a reset unit that continuously stops.

The present invention has the above-described structure, in which the setting unit sets a temperature lower than the temperature detected by the temperature detecting unit when the pressure switch is actuated by a predetermined value, and when the temperature exceeds the set temperature thereafter, the stop unit stops the combustion. The variation of the approximate detection of the pressure due to is corrected, the combustion is surely stopped before the pressure rises, and the pressure switch operates even if it is corrected. When the number of counts exceeds a predetermined number, the reset unit resets and does not burn again, ensuring safety and exhibiting sufficient heating capacity.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the embodiment, the same parts as those in FIG. 6 are designated by the same reference numerals for convenience, and the description thereof will be omitted.

FIG. 1 shows a system block diagram of the present invention. In FIG. 1, 18 is a heat transfer means having the same function as in FIG.
Is attached to the pipe with a pressure switch that detects pressure,
The switch is configured to be normally closed and opened when the pressure rises. When the pressure switch 19 is opened, the first solenoid valve 1, the second solenoid valve 2, the opening / closing valve 3, the third solenoid valve 4, and the fourth solenoid valve are opened. The power supply to the valve 5, the compressor 6, the heat source 11, etc. is stopped. 20 is a thermistor that detects the temperature of the heat medium, that is, the refrigerant, and is attached to the pipe. Reference numeral 21 is a control unit for controlling the heat source 11, and 22 is a setting unit for setting a temperature TS = TP−ΔTS lower than the detection temperature TP of the thermistor 20 when the pressure switch 19 is opened due to a pressure increase. When the pressure switch is closed again due to the decrease in pressure, combustion is performed again. The reference numeral 23 designates a stop portion for stopping the combustion of the heat source 11 when the temperature T detected by the thermistor 20 becomes higher than the set temperature TS set by the setting portion 22, that is, T> TS. A counter 24 counts the number of operations of the pressure switch 19. Reference numeral 25 is a reset unit, and the number of pressure switch operations counted by the counter 24 is a predetermined number (for example, once).
When the temperature exceeds, the heat source 11 is stopped, and combustion is not restored even if the pressure switch is closed again. FIG. 2 shows an embodiment of the electric circuit of the control unit 21. A series circuit of a first solenoid valve 1 and a first relay 26 that opens and closes it, a series circuit of a second solenoid valve 2 and a second relay 27 that opens and closes it, and a series circuit of a shutoff valve 3 and a third relay 28 that opens and closes it. Circuit, series circuit of third solenoid valve 4 and fourth relay 29 that opens and closes it, series circuit of fourth solenoid valve 5 and fifth relay 30 that opens and closes it, compressor 6 and sixth relay that opens and closes it A series circuit of 31, a heat source 11 and a series circuit of a seventh relay 32 for driving and controlling the heat source 11 and an AC power supply 33 are connected in parallel, and a low voltage circuit is formed through a transformer 34 connected in parallel with the AC power supply 33. , Low voltage circuit is a diode bridge
Full-wave rectification is performed by 35, smoothing is performed by the capacitor 36 to form a DC power supply, and a stable voltage is supplied to the microcomputer 38 by the constant voltage IC 37. A first transistor 39 that drives the first relay 26 and a second transistor that drives the second relay 27
40, third transistor 41 for driving third relay 28, fourth
Fourth transistor 42 driving relay 29, fifth relay 30
The microcomputer 38 controls all of the fifth transistor 43 for driving, the sixth transistor 44 for driving the sixth relay 31, and the seventh transistor 45 for driving the seventh relay 32. A series circuit of the first relay 26 and the first transistor 39,
Series circuit of second relay 27 and second transistor 40, series circuit of third relay 28 and third transistor 41, fourth relay 29
And a series circuit of the fourth transistor 42, the fifth relay 30 and the fifth
Series circuit of transistor 43, series circuit of sixth relay 31 and sixth transistor 44, seventh relay 32 and seventh transistor
45 series circuits are connected in parallel, and the parallel circuit and the pressure switch 19 are connected in series and connected to the series power source. That is, when the pressure switch 19 is opened, no voltage is supplied to all relays, and the first solenoid valve 1, the second solenoid valve 2, the opening / closing valve 3, the third solenoid valve 4, and the fourth solenoid valve 5 are closed, and the compressor is closed. 6. The heat source 11 is stopped. If the pressure switch 19 is closed by the first resistor 46 connected in series with the pressure switch 19 and the pressure switch operation detection circuit formed by the eighth transistor 47 and the second resistor 48, it is in the LO or open state. if there is
HI inputs to the microcomputer 38. Further, the voltage across the third resistor 49 connected in series with the thermistor 20 is input to the microcomputer 38, the voltage is known by AD conversion, and the resistance value of the thermistor 20, that is, the temperature of the mounting portion of the thermistor 20 is detected. Fig. 3 shows the characteristics of pipe pressure and detected temperature. When the pipe pressure P> PMAX, the pressure switch 9 is closed to stop the equipment. However, for safety, setting PS smaller than PMAX and stopping the combustion of the heat source 11 when P> PS can suppress the pressure increase. It suffices to detect this PS point approximately by the temperature of the thermistor 20, but there are variations in the pipe pressure and the detected temperature, and there are characteristics a and b. Therefore, when the microcomputer 38 inputs HI from the pressure switch operation detection circuit, it is assumed that the pressure switch 19 is opened, that is, the pipe pressure P = PMAX is detected, and a temperature TS lower than the temperature TP detected by the thermistor 20 at that time is set by ΔTS. . Therefore, if the characteristic is a, the detected temperature is TPa
Set TSa = TSa−ΔTS lower than ΔTS, and TSb = TPb−ΔTS lower than the detected temperature TPb if the characteristic is b.
After that, when the pressure switch returns, the microcomputer 38
When the temperature T detected by the thermistor 20 exceeds the set temperature, the seventh transistor 45 is turned off and the seventh relay 32 is turned on.
FF is performed and the combustion of the heat source 11 is stopped. If the pressure switch opens again during combustion, it is reset as if the pressure switch itself, the temperature detection means, or the equipment itself such as a blockage of the pipe has occurred. Do not restart combustion. A flow chart of the above control is shown in FIG. In FIG. 4, the symbols of parts having functions are added to the side.

Next, another embodiment of the present invention will be described with reference to FIG.

In FIG. 5, the difference from the above embodiment is that the pressure switch 19
Is connected to the high voltage side. If the pressure switch 19 is closed, the diode of the photocoupler 50 and the fourth resistor 51 are connected.
Since the current flows in the series circuit of, the current flows through the transistor of the photocoupler 50 and the fifth resistor 52, the microcomputer 38 detects the IO input, and if the pressure switch 19 is opened, the current of the diode of the photocoupler 50 is detected. Since it does not flow, current does not flow in the transistor and the microcomputer 38
Detect HI input. According to this configuration, there is an effect that a danger due to welding of the relay can be avoided and a safer system can be provided. In the above description, the temperature sensor is attached to the same place as the pressure switch, but the same effect can be obtained by attaching the temperature sensor to another place such as an indoor unit.

Effects of the Invention As described above, according to the control device for an air conditioner of the present invention, the following effects are obtained.

(1) Once the pressure switch is activated due to the pressure increase, the combustion is stopped at the set temperature set with the temperature when the pressure switch is activated as a reference, so the variation of the pressure approximation due to the detected temperature is corrected and the pressure switch It is possible to provide a safe air conditioner that surely stops combustion before operating and does not raise the pressure to the pressure switch operating point.

(2) If the number of times the pressure switch is operated exceeds a predetermined number, it is regarded as an abnormality of the pressure switch, an abnormality of the temperature detecting means, or an obvious abnormality of the equipment such as a blocked pipe, and the equipment is reset. It is possible to provide a safe air conditioner.

(3) In addition, since the variation of the pressure approximation by the temperature sensor can be corrected, an air conditioner having a high heating capacity that does not stop combustion in a safe pressure region and can exert a sufficient heating effect is provided. Can be provided.

(4) Since the variation of the pressure approximation due to the detected temperature of the temperature sensor can be corrected, the selection range of the mounting location of the temperature sensor can be widened and the design can be facilitated.

[Brief description of drawings]

FIG. 1 is a system block diagram of a control device for an air conditioner in one embodiment of the present invention, FIG. 2 is an electric circuit diagram of a control unit, and FIG. 3 is a characteristic diagram showing a relationship between detected temperature and pipe pressure,
FIG. 4 is a flow chart showing a flow of processing of the microcomputer, FIG. 5 is an electric circuit diagram of a control unit of another embodiment, and FIG. 6 is a system diagram for explaining a conventional example. 11 ... Heat source, 13 ... Heat exchanger, 18 ... Heat transfer means, 19 ...
… Pressure switch, 20… Temperature detection means, 21… Control section,
22 …… Setting section, 23 …… Stop section, 24 …… Counter, 25 ……
Reset section.

Claims (1)

[Claims] 1. A heat source for heating a heat medium by combustion, a heat exchanger for heating air by heat exchange with the heat medium, and a heat transfer means for circulating the heat medium between the heat source and the heat exchanger.
The control unit includes a temperature detection unit that detects the temperature of the heat medium flowing into the heat exchanger, a pressure switch that operates by an increase in the pressure of the heat medium to stop combustion, and a control unit that controls the heat source. Is a setting unit that sets a temperature lower by a predetermined value than the temperature detected by the temperature detection unit when the pressure switch is activated, and the temperature detected by the temperature detection unit after the pressure switch is restored again is the set temperature of the setting unit. Of the air conditioner having a stop portion for stopping combustion when the temperature exceeds the limit, a counter for counting the number of times of operation of the pressure switch, and a reset portion for continuously stopping the heat source when the number of times of operation of the counter exceeds a predetermined number. Control device.