JPH0723795B2 - Control device for air conditioner equipped with refrigerant heater - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device in an air conditioner equipped with a refrigerant heater for improving heating capacity at a low outside air temperature, and more particularly to a thermistor for detecting the temperature of the refrigerant heater. Regarding disconnection detection control.

2. Description of the Related Art Conventionally, the purpose of this type of air conditioner has been to heat a refrigerant heater with a fuel such as gas or oil to obtain a heating capacity, and therefore from the viewpoint of ensuring safety and feeling. It is generally known that the heater is equipped with a thermistor to control ON / OFF of combustion.

As is clear from FIG. 6, the control method is such that the temperature of the refrigerant heater rises from the start of combustion and finally reaches t ₁ to stop combustion. After that, when the temperature of the refrigerant heater falls and drops to t _{2, the} combustion operation is performed again. That is, t ₁ and t ₂ are determined in advance by setting the thermistor, and the temperature of the refrigerant heater is kept constant.

As is clear from this, the control of the thermistor provided in the refrigerant heater in this type of air conditioner was considered to be an important position.

Therefore, in the case of conventional control, a method of detecting disconnection of the thermistor alone is generally adopted. Particularly in the case of a water heater, control as shown in FIG. 7 has been known. This control sets the combustor temperature stop point, return point, and disconnection point as absolute values, and normally detects the disconnection under the premise that the combustor temperature is distributed in the actual operation range during stop / reset operation. It was control.

Problems to be Solved by the Invention In the conventional control as described above, when the control target is an air conditioner of this type, a refrigerant heater is provided on the outdoor unit side. A problem occurs when starting at -20 ℃.

In other words, in the characteristic (negative characteristic) of the thermistor, -20 ° C is several MΩ.
Therefore, the thermistor has a possibility of erroneous detection when the conventional control is performed.

In view of the above points, the present invention provides a break temperature detection point of the thermistor in the vicinity of room temperature in advance, and stops the combustion when the temperature is below a certain time after the start of combustion to the refrigerant heater, whereby the problem The point is eliminated.

Means for Solving Problems The present invention, in order to solve the above conventional problems, a thermistor for detecting the temperature of the refrigerant of the refrigerant heater, a detecting means for detecting the detected temperature of the thermistor, and The control unit includes a timer unit and a drive / stop control unit for the refrigerant heater.

The present invention, by the above-described configuration, if the temperature of the thermistor is lower than a predetermined temperature after a certain time from the start of heating the refrigerant, the refrigerant heater is forcibly stopped, so that the thermistor disconnection detection or connection error can be accurately detected. Therefore, the safe operation of this type of air conditioner is ensured.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a refrigeration cycle diagram in the present embodiment, where 1 is a refrigerant heater, 2 is a compressor, 4 is a thermistor for detecting the temperature of the refrigerant heater 1, and 3 is the temperature of the thermistor 4. Control device for controlling operation / stop of the refrigerant heater 1, 5 four-way valve, 6 two-way valve, 7 decompressor, 8 check valve, 9 outdoor heat exchanger, 10 indoor heat exchanger Indicates.
The compressor 2, the four-way valve 5, the indoor heat exchanger 10, the two-way valve 6 and the refrigerant heater 1 are connected in an annular shape.

Further, in the figure, the refrigerant flows through a route indicated by a solid line during cooling and a dotted line during heating. Since the present invention is based on the content of the refrigerant heating operation during heating, only the description of heating operation will be given below.

Next, the configuration of the sequence circuit diagram in this embodiment will be described with reference to FIG. The same functions as those in FIG. 1 are designated by the same numbers.

In the figure, 11 is a power source, 12 is an operation switch, 13 is a timer relay, and 1a is a refrigerant heater driving relay.

Next, the operation in the configuration shown in FIGS. 1 and 2 will be described.

First, when the operation switch is turned on, the compressor 2, the four-way valve 5 and the timer relay 13 operate. At this time, the two-way valve 6 is operated for a preset time of the timer relay 13 while it is closed (hereinafter, this operation is referred to as a refrigerant removal operation). When the timer relay 13 times up, the timer relay contact 13
Since a turns on, the two-way valve 6 opens. Therefore, the refrigerant circulates in the cycle indicated by the dotted line of the refrigeration cycle. At the same time, the controller 3 and the refrigerant heater 1 are energized, so that the refrigerant heating operation is started.

By the above operation, the refrigerant heating operation during heating is performed.

Next, an electronic circuit diagram showing an example of the thermistor detecting means and the refrigerant heater operating / stopping means will be described with reference to FIG.

In the figure, the connecting portion between the thermistor 4 and the resistor 15 is connected to a microcomputer 14 (hereinafter referred to as a microcomputer). The other terminal of the microcomputer 14 is the inverter element 16
Of the inverter element 16 and the output side of the inverter element 16 are connected to the 12V power source via the refrigerant heater driving relay coil 1b.

In the configuration shown in the figure, since the divided voltage formed by the thermistor 4 and the resistor 15 is an A / D input, the temperature of the thermistor 4 can always be input.

Therefore, by forming a temperature point for controlling the refrigerant heater 1 and a timer control in advance as a program,
It enables fine control.

In the present embodiment, the refrigerant heating stop point in normal operation is set to t ₁ , the return point at that time is set to t ₂ , and the disconnection detection point of the thermistor 4, which is the main object of the present invention, is set to t ₃ in the normal temperature range. By doing so, after a certain period of time from the start of the refrigerant heating operation, it becomes t ₃ or more in the case of the constant operation and becomes t ₃ or less in the case of the thermistor 4 being disconnected. At that time, the relay coil 1b for driving the refrigerant heater is connected. It is turned off and the refrigerant heater 1 is forcibly stopped.

FIG. 4 is a distribution diagram showing the modes detected by the microcomputer 14 in the patterns of three types (normal temperature, low temperature, disconnection) at the time of starting the operation of the refrigerant heater 1 in the control of the present embodiment.

As is clear from the figure, if the thermistor is disconnected, it will always be distributed below t ₃ , and even if the thermistor is normal, it will start without problems because the judgment ignore time of T minutes is provided in the case of starting at low temperature. It is a thing. In this embodiment, specific numerical values are set to t ₃ = 25 ° C. and T = 60 seconds.
Regarding the determination of this value, actual use in cold regions is -20 ° C.
It is a numerical example determined from the rising distribution of this air conditioner, and in other air conditioners, there is a difference depending on the heating capacity and the heat exchange capacity of the refrigerant heater, so it is necessary to determine each time. . FIG. 5 shows the microcomputer in this embodiment.
FIG. 16 is a flowchart showing a control example of 14.

As described above, according to the present embodiment, the thermistor that detects the temperature of the refrigerant heater constantly monitors even if an abnormality such as a disconnection or a poor contact occurs, so that it is possible to protect the abnormal overheat operation of the refrigerant heater. It is what is done.

In the above embodiment, the operation of the refrigerant heater, the stopping means, the timer means, and the thermistor temperature detecting means are performed by the microcomputer, but the above control can be performed by forming discrete components such as capacitors, resistors, and ICs. Needless to say.

EFFECTS OF THE INVENTION As described above, according to the present invention, the disconnection detection of a single thermistor that detects the temperature of the refrigerant heater is constantly monitored, so that the disconnection such as the deterioration of the thermistor with age can be detected early.

Therefore, since the abnormal temperature rise operation of the refrigerant heater can be prevented in advance, the safe operation of the air conditioner is ensured.
Further, since it becomes possible to detect the thermistor cross-section early, it is expected that the connection of the thermistor and the control unit will be a connector to reduce the number of work steps and improve the serviceability. Also, when the refrigerant heater starts up at a low temperature (for example, in a cold region), the resistance value of the thermistor is large (close to ∞), and it is erroneously detected as a disconnection. Therefore, it has various advantages such as prevention.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle diagram of an air conditioner showing an embodiment of the present invention, FIG. 2 is a sequence circuit diagram during heating of the air conditioner, and FIG. 3 is an electronic circuit diagram showing an example of the present embodiment. FIG. 4 is an explanatory view showing the control of the refrigerant heater in the same embodiment, FIG. 5 is a flow chart showing the control of the same embodiment, and FIG. 6 is an explanation showing the control contents of the refrigerant heater in the conventional embodiment. FIG. 7 and FIG. 7 are explanatory views showing the thermistor disconnection detection of a general water heater. 1 ... Refrigerant heater, 1b ... Relay coil for driving refrigerant heater, 2 ... Compressor, 3 ... Control device, 4 ... Thermistor, 5 ... Four-way valve, 6 ... Two-way valve, 10 ... … Indoor heat exchanger, 14 …… Microcomputer, 16 …… Inverter element.

Claims (1)

[Claims] 1. A refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a two-way valve, and a refrigerant heater are annularly connected, a thermistor for detecting the temperature of the refrigerant in the refrigerant heater, and this thermistor. Detection means for detecting the detected temperature, a timer means at that time, and a control section having a refrigerant heater operation / stop control means, and the control section is a thermistor after a certain time from the start of refrigerant heating. If the detected temperature is equal to or higher than the predetermined temperature, the operation or stop is repeated at the set temperature during the refrigerant heating operation, and if the detected temperature is equal to or lower than the predetermined temperature after a predetermined time from the start of the refrigerant heating, the thermistor is abnormal. An air conditioner control device equipped with a refrigerant heater for determining and forcibly stopping the refrigerant heating operation.