JP2507783B2 - Control device for air conditioner - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner that heats a heat medium by combustion, and more particularly to control of a combustion amount.

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. But in the case of heat pump air conditioners,
There is a problem that the capacity decreases at the time of low outside temperature, which requires the most heating, and high-temperature strong wind cannot be blown out.

To solve such a problem, for example, Japanese Patent Application No. 61
There is a system of −245729. That is, in FIG. 9, at the time of heating operation, first, at the start of heating, the first solenoid valve 1,
The second solenoid valve 2 and the opening / closing valve 3 are closed, and the third solenoid valve 4,
The fourth solenoid valve 5 is 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 outdoor refrigerant condenser 8 and the accumulator 9 are provided.
And, the refrigerant distributed in the various refrigerant pipes connected to it is sucked down by the operation of the compressor 6,
All the refrigerant is pumped up to the refrigerant heater 11 via the first check valve 10. After the pump down operation, the compressor 6 is stopped, the fourth solenoid valve 5 is closed, and a burner (not shown) is ignited to start the heating operation. The heat medium pumped up to the refrigerant heater 11 is heated by the burner to evaporate and the evaporation pressure rises, and the evaporated high-temperature and high-pressure refrigerant gas flows from the refrigerant heater 11 to the third electromagnetic 4 and from the refrigerant pipe 12 to the indoor heat. It is pumped to the 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. Refrigerant liquid is the third from the refrigerant pipe 15
After passing through the check valve 16, the liquid flows into the liquid receiver 17 and is received. When the liquid level of the received liquid reaches a certain level, the on-off valve 3 is opened, and the evaporation power is applied to the liquid receiver 17, and the static pressure becomes the same as that of the refrigerant heater 11. The refrigerant liquid in the liquid receiver 17 flows into the refrigerant heater 11 due to the surface head differential pressure. 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 guarantee safety and to prevent the pressure from rising to the operating point of the pressure switch. When a temperature sensor is attached to the temperature sensor to detect an increase in temperature, combustion is stopped to suppress an increase in pressure.

However, in the above method, 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 that is approximated by the detected temperature due to variations in the mounting location and mounting method of the temperature sensor, and there is a risk that the pressure rise due to temperature cannot be detected and the pressure rises to the pressure switch operating point. If the design is made to reliably detect the temperature before operating the pressure switch in consideration of variations, there is a problem that the combustion is stopped and the heating operation cannot be sufficiently performed even when the refrigerant is at a low temperature.

The present invention solves such a conventional problem, and corrects a variation that occurs when the pipe pressure is approximated and detected by the pipe temperature, and reliably controls the combustion amount 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 A pressure switch and a control unit for controlling the heat source, and the control unit sets a correction value of a detected temperature or a combustion amount according to a temperature detected by the temperature detection unit when the pressure switch operates. A configuration including a calculation unit that calculates a combustion amount from the detected temperature of the temperature detection unit and a correction value of the setting unit, and a heat source control unit that controls the combustion amount of the heat source based on the calculation result of the calculation unit And.

Action The present invention, by the above configuration, sets the correction value from the temperature detected by the temperature sensor when the pressure switch is activated,
After that, since the combustion amount is calculated and determined by the temperature corrected by the correction value set by the detected temperature, the variation in the approximate detection of the pressure due to the temperature is corrected, and the combustion amount control reliably suppresses the pressure rise to ensure safety. It is possible to secure it and to exert 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. 9 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. First
In the figure, 18 is a heat transfer means having the same function as in FIG.
Reference numeral 19 denotes a pressure switch for detecting pressure, which is attached to the pipe, is normally closed, and is opened when the pressure rises. When the pressure switch 19 is opened, the first solenoid valve 1 and the second solenoid valve 2 are opened. , Open / close valve 3, third solenoid valve 4, fourth
The power supply to the solenoid 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 section for controlling the heat source 11, and 22 is a setting section for calculating a difference ΔT = TS-TP between a temperature TP detected by the thermistor 20 and a predetermined temperature TS when the pressure switch 19 is opened due to an increase in pressure. ΔT is set as a correction value. If the pressure switch 19 does not open, △ T = 0
Is. Reference numeral 23 denotes a calculation unit, which is the correction temperature TH corrected by the detection temperature T of the thermistor 20 and the correction value ΔT set by the setting unit 22.
The combustion amount Q1 is calculated from = T + ΔT. Reference numeral 24 is a second thermistor for detecting the room temperature, and 25 is a second calculation unit for calculating the combustion amount Q2 from the detected temperature of the second thermistor 20. 26 is Q1
A comparison unit that compares Q2 and outputs the smaller one as the combustion amount Q, and 27 is a heat source control unit that combusts the heat source 11 with the combustion amount input from the comparison unit. FIG. 2 shows an embodiment of the electric circuit of the control unit 21. First solenoid valve 1 A series circuit of a first relay 28 that opens and closes it, a series circuit of a second solenoid valve 2 and a second relay 29 that opens and closes it, a series circuit of a shutoff valve 3 and a third relay 30 that opens and closes it. , A series circuit of a third solenoid valve 4 and a fourth relay 31 for opening and closing it, a fourth solenoid valve 5 and a fifth circuit for opening and closing it
A series circuit of the relay 32, a series circuit of the compressor 6 and a sixth relay 33 for connecting and disconnecting the compressor 6, a series circuit of the heat source 11 and a seventh relay 34 for driving and controlling the heat source 11 and an AC power source 35 are connected in parallel, and an AC power source. A low-voltage circuit is formed via a transformer 36 connected in parallel with 35, full-wave rectification is performed by a low-voltage circuit diode bridge 37, smoothing is performed by a capacitor 38 to form a DC power supply, and a stable voltage is generated by a constant-voltage IC 39. Supply to the microcomputer 40. First transistor 4 driving the first relay 28
1, the second transistor 42 for driving the second relay 29, the third
Third transistor 43 driving relay 30, fourth relay 31
The fourth transistor 44 for driving, the fifth transistor 45 for driving the fifth relay 32, the sixth transistor 46 for driving the sixth relay 33, and the seventh transistor 47 for driving the seventh relay 34 are all controlled by the microcomputer 40. Control. Series circuit of the first relay 28 and the first transistor 41, series circuit of the second relay 29 and the second transistor 42, series circuit of the third relay 30 and the third transistor 43, series circuit of the fourth relay 31 and the fourth transistor 44 Circuit, series circuit of fifth relay 32 and fifth transistor 45, sixth relay 33 and sixth transistor 46
, A series circuit of the seventh relay 34 and the seventh transistor 47 is connected in parallel, and the parallel circuit and the pressure switch 19
Are connected in series and connected to a series power supply. 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, heat source 11
Stops. Here, the pressure switch 19 is connected in series with the first resistor 48, and the pressure switch operation detection circuit formed by the eighth transistor 49 and the second resistor 50 causes the pressure switch to operate.
If 19 is closed, LO is input to the microcomputer 40, and if it is open, HI is input to the microcomputer 40. Further, the voltage across the third resistor 51 connected in series with the thermistor 20 is input to the microcomputer 40, and the voltage is known by AD conversion and the thermistor 20 is detected.
Resistance value, that is, the pipe temperature of the mounting portion of the thermistor 20 is detected. The fourth resistor connected in series with the thermistor 24
The voltage across 52 is input to the microcomputer 40, the voltage is known by AD conversion, and the resistance value of the thermistor 24, that is, the room temperature of the mounting portion of the thermistor 24 is detected. Fig. 3 shows the characteristics of pipe pressure and detected temperature. When the pipe pressure P> PMAX, the pressure switch 9 is opened to stop the equipment. However, for safety, the pressure rise can be suppressed by controlling the combustion amount of the heat source 11 in the region of P <PMAX. In this P <PMAX region, the pipe pressure P should be approximately detected by the detection temperature T of the thermistor 20, but the pipe pressure and the detection temperature have variations as shown in FIG. There is a characteristic. When the microcomputer 40 inputs HI from the pressure switch operation detection circuit, the pressure switch 19 is opened, that is, the pipe pressure P = PMAX is detected, and the temperature TP detected by the thermistor 20 at that time and the preset temperature TS are set. Difference ΔT = TS-TP
Is set as a correction value. If the characteristic is a, then ΔTa = TS-
If the characteristics are TPa and b, ΔTb = TS−TPb, and thereafter the microcomputer 40 calculates the combustion amount based on the temperature TH = T + ΔT obtained by correcting the temperature detected by the thermistor 20. That is, when the pipe pressure P = P1, the temperature detected by the thermistor 20 is T1a for the characteristic of a and T1b for the characteristic of b, but it is corrected by TH = T1a + ΔTa, TH = T1b + ΔTb. Even if the characteristic is b or b, it becomes a straight line of virtual c and the variation is corrected. In FIG. 4, the calculation unit 23 displays the correction temperature TH = T +.
The calculation result of calculating the combustion amount Q1 from ΔT is shown. Burning amount Q1
Assuming that you can switch between two levels of QH and QL,
If the correction temperature TH is TH <TH1, set Q1 = QH. When the correction temperature rises and TH> TH1, the combustion amount is set to Q1 = QL to suppress the pressure rise. When the correction temperature further rises and TH> TH2, for safety, Q1 = 0, that is, combustion is stopped. FIG. 5 shows the calculation result of the second calculation unit 25 when the second thermistor 24 detects the room temperature TR. If room temperature TR is TR <TR1, Q2 = Q
H, room temperature rises and TR> TR1, Q2 = QL, further rises TR
When> TR2, Q2 = 0, that is, combustion is stopped. TR1 and TR2 change depending on the set temperature set by the user,
By controlling the combustion amount by the room temperature TR, the room temperature is controlled to match the user's set temperature. The comparison unit 26 compares the calculation result Q1 of the calculation unit 23 and the calculation result Q2 of the second calculation unit 26 and outputs the smaller combustion amount as Q to the heat source control unit 27. The relationship between the corrected temperature TH, the room temperature TR and the output Q of the comparison unit 26 is shown in the following table.

A flowchart of the above control is shown in FIG. In FIG. 6, the symbols of parts having functions are added to the side. The above embodiments have the effects of controlling the room temperature at a constant level and ensuring safety.

Next, another embodiment of the present invention will be described with reference to FIG.
In FIG. 7, the point different from the above embodiment is the pressure switch 19
Is connected to the high voltage side, and if the pressure switch 19 is closed, the diode of the photo-cabler 53 and the fifth resistor 54
Since the current flows in the series circuit of, the current flows in the transistor of the photocoupler 53 and the sixth resistor 55, the microcomputer 40 detects the L0 input, and the diode current of the photocoupler 53 flows if the pressure switch 19 is opened. Since there is no current, no current flows through the transistor and the microcomputer 40
Detect 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. Further, in the above description, the combustion amount is explained in two stages of QH and QL, but the same effect can be obtained even if the number of stages is increased or can be continuously changed. In that case, the relationship between the combustion amount and the detected temperature is previously expressed as Q = k1 * T + k2 (k1
Set k2 as a constant), and once the pressure switch is activated, the detected temperature is corrected with the correction value ΔT. For example, if the detected temperature is T2, burn with Q2 = k1 * (T2 + ΔT) + k2 The amount will be calculated. In this case, the setting unit 22 sets the correction value of the combustion amount as ΔQ instead of the correction value of the detected temperature, and the calculation unit 23 calculates the combustion amount by Q = k1 * T + k2-ΔQ. When the detected temperature is T2, Q2 = k1 * T2 + k2-ΔQ and the same result can be obtained. As described above, when the number of stages of the combustion amount is increased or can be continuously changed, fine combustion amount control can be performed.

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) Since the correction value is set according to the temperature when the pressure switch operates due to the pressure increase and the combustion amount is controlled by the corrected temperature thereafter, it is possible to provide a safe air conditioner capable of reliably suppressing the pressure increase.

(2) Further, since the variation of the pressure approximation by the temperature sensor can be corrected, on the contrary, the air conditioning with a high heating capacity, which does not lower the combustion amount more than necessary in the safe pressure range and can sufficiently exert the heating effect. Machine can be provided.

(3) Since variations in pressure approximation due to the temperature detected by the temperature sensor can be corrected, the selection range of the mounting location of the temperature sensor is widened, and an easy design is possible.

[Brief description of drawings]

FIG. 1 is a system block diagram of a control device for an air conditioner according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of a control portion of the air conditioner, and FIG. 3 is a relationship between detected temperature and pipe pressure. FIG. 4 is a characteristic diagram showing the relationship between the correction temperature and the combustion amount, and FIG. 5 is a characteristic diagram showing the relationship between the indoor temperature and the combustion amount.
FIG. 6 is a flow chart showing the flow of processing of the microcomputer, FIG. 7 is an electric circuit diagram of the control unit of another embodiment, and FIG. 8 is a characteristic diagram showing the relationship between the detected temperature and the combustion amount of the other embodiment. , FIG. 9 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 ... Calculation section, 27 ... Heat source control section.

Claims (2)

(57) [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 for setting the correction value of the detected temperature or the combustion amount according to the detection temperature of the temperature detection unit when the pressure switch is operated, and the combustion amount from the detection temperature of the temperature detection unit and the correction value of the setting unit. An air conditioner control device comprising: a calculation unit that performs calculation; and a heat source control unit that controls a combustion amount of the heat source based on a calculation result of the calculation unit. 2. The control section has a second temperature detecting section for detecting a room temperature and a second calculating section for calculating a combustion amount based on the temperature detected by the second temperature detecting means. The control device for an air conditioner according to claim 1, further comprising a comparison unit that compares the calculation results of the two calculation units and outputs the one with a smaller combustion amount to the heat source control unit.