JPH0460330A - Air conditioner - Google Patents

Abstract

PURPOSE:To enable heating operation to be continued even in the case that an outdoor heat exchanging temperature sensor is in its abnormal condition by a method wherein when an abnormal discriminating means judges an abnormal state of the outdoor heat exchanging temperature sensor, an auxiliary frosting sensing means is selected and a defrosting control means is operated with a defrosting signal from an auxiliary frosting sensing means. CONSTITUTION:An abnormal state judging means 17 monitors an abnormal state caused by a trouble of an outdoor heat exchanging temperature sensor 8 and a state is changed to a condition in which the outdoor heat exchanging temperature sensor 8 detects a defrosting discriminating temperature not applicable, the outdoor heat exchanging temperature sensor 8 judges that this state is abnormal and outputs a signal indicating this state. The sensor abnormal state dealing means 18 prohibits a main frosting sensor means 14 in response to an abnormal signal from an abnormal state discriminating means 17 and in place of it, it selects an auxiliary frosting sensing means 16. Then, a defrosting signal is sent from the auxiliary frosting sensor means 16 to the defrosting control means 15 so as to perform a defrosting operation with the defrosting control means 15. With such an arrangement, operation of an air conditioner can be continued without stopping any heating operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an air conditioner separated into an outdoor unit and an indoor unit, and particularly to a defrosting control device thereof.

(Prior Art) When an air conditioner is operated for heating, frost may form on the outdoor heat exchanger, and as a result, the heating efficiency decreases, so it is necessary to defrost the air conditioner. This defrosting is performed by heating the outdoor heat exchanger by some method.

Conventionally, an outdoor unit is equipped with an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger, such as a defrosting thermoswitch, and a defrosting timer that sets the defrosting time. By working with the timer, defrosting operation control is performed independently of the operation control on the indoor unit side. This is because the output of the defrosting thermo switch can only be obtained from the outdoor unit.

(Problem to be solved by the invention) However, in conventional air conditioners, defrosting is performed by detecting frost formation using an outdoor heat exchanger temperature sensor, so if the outdoor heat exchanger temperature sensor of the outdoor unit malfunctions, However, the heating function of the air conditioner also stopped, making it impossible to continue heating.

The present invention has been made in order to solve the above problems, and aims to provide an air conditioner that can continue its heating operation without stopping even if the outdoor heat exchanger temperature sensor becomes abnormal. do.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the air conditioner of the present invention prevents frost formation in the outdoor unit when the temperature detected by the outdoor heat exchanger temperature sensor is below a reference value. The indoor unit is equipped with a main frost detection means that makes a judgment and outputs a defrost signal, and a defrost control means that receives this defrost signal and performs a defrosting operation. an auxiliary frost detection means for determining the presence or absence of frost and outputting a defrosting signal; an abnormality determination means for determining an abnormality in the outdoor heat exchanger temperature sensor; and an abnormality determination means for determining an abnormality in the outdoor heat exchanger temperature sensor. In this case, an auxiliary frost detection means is selected in place of the main frost detection means, and a sensor abnormality response means is provided for operating the defrost control means in response to a defrost signal from the auxiliary frost detection means. It is.

(Function) With the above configuration, when the outdoor heat exchanger temperature sensor changes to a state where it detects a defrosting determination temperature that normally does not exist, for example, 90°C or higher or 30°C or lower, the abnormality determination means detects the outdoor heat exchanger temperature. It is determined that the sensor is abnormal. As a result, the sensor abnormality response means corrects the normal defrosting determination and switches to defrosting determination based on the indoor heat exchanger temperature and the room temperature.

Therefore, the air conditioner can continue operating without stopping the heating operation even when the outdoor heat exchanger temperature sensor is abnormal, and continues to operate while defrosting until the outdoor heat exchanger temperature sensor is repaired from failure. be able to.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings.

The basic configuration of the air conditioner of the present invention is shown in FIG. 1. The refrigeration cycle of the air conditioner consists of 1 degree compressor, 2. M external heat exchanger 3. Pressure reducing device4. The indoor heat exchangers 5 are connected to each other in sequence. 6 is an outdoor fan, and 7 is an indoor fan.

The four-way valve 2 switches between cooling and heating, and when the refrigerant flows in the direction of the dashed arrow, a heating operation state is entered.

Reference numeral 8 denotes an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger, and in this embodiment, it consists of a defrosting thermoswitch. 9
is an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger,
Reference numeral 10 denotes an indoor temperature sensor that detects the indoor temperature, and in this embodiment, both are composed of a thermistor.

11 is an outdoor controller, and 12 is an indoor controller, each of which is mainly configured with a microcomputer. The indoor IIJ controller 12 is a temperature setting device 1 configured with a remote control.
3 and inputs from the indoor temperature sensor 10 and the indoor heat exchanger temperature sensor 9, it has the functions of controlling the motor rotation of the indoor fan 7, commanding the operating frequency of the compressor 1, and controlling the operation of the entire air conditioner. ing. The outdoor controller 11 decodes the serial operation signal sent from the room, controls the rotation speed of the pressure @all via an inverter (not shown), and adjusts the heating capacity or the cooling capacity.

The defrosting control device for the air conditioner is configured in terms of software or hardware as shown in FIG. 2.

That is, in FIG. 2, the outdoor controller 12 is provided with a main frost detection means 14 and a defrost control means 15. The main frost detection means 12 monitors the outdoor heat exchanger temperature te detected by the outdoor heat exchanger temperature sensor 8 to determine frost formation, and when defrosting is required, for example, the outdoor heat exchanger temperature te is set. When the value t1 becomes lower than, for example, -8°C, a defrosting timer is started, and after a predetermined timer period elapses, for example, 20 seconds, a defrosting signal is output, and then the outdoor heat exchanger temperature te or the set value t2,
For example, this circuit causes the defrosting signal to disappear when the temperature rises to +1° C. or higher. Further, the defrosting control means 15 controls the compressor 1
．． This circuit controls the outdoor fan 6, four-way valve 2, etc. to perform a predetermined defrosting operation, and while receiving the above-mentioned defrosting signal, the compressor 1 is in operation, the outdoor fan 6 is stopped, and the four-way valve is in operation. 2
switches to cooling cycle mode. Therefore, in normal times, for example, by defrosting determination of the outdoor heat exchanger temperature sensor 8,
Defrosting operation is performed when the detected temperature te is below 18°C, and then returns to heating operation when the detected temperature te is above +1°C.

On the other hand, the indoor controller 12 is provided with an auxiliary frost detection means 16, and the outdoor controller 11 is further provided with an abnormality determining means 17 for determining an abnormality in the outdoor heat exchanger temperature sensor 8; When it is determined that there is an abnormality in the outdoor heat exchanger temperature sensor 8, the auxiliary frost detection means 16 is selected instead of the main frost detection means 14, and the defrost control means is activated by the defrost signal from the auxiliary frost detection means. 15 is provided.

The abnormality determination means 17 monitors abnormalities caused by failure of the outdoor heat exchanger temperature sensor 8, and detects a state in which the outdoor heat exchanger temperature sensor 8 detects an impossible defrost determination temperature, for example, 90°C or higher or -30°C or lower. If the temperature changes to , it is determined that the outdoor heat exchanger temperature sensor 21 is abnormal, and a signal to that effect is output. The sensor abnormality response means 18 selects the main frost detection means 14 under normal conditions, but when an abnormality signal is generated from the abnormality determination means 17, the sensor abnormality response means 18 inhibits the main frost detection means 14 and selects the auxiliary frost detection means 14 instead. Select frost detection means 16.

An example of the configuration of the auxiliary frost detection means 16 is shown in FIG. 3, which is similar to that disclosed in Japanese Patent Publication No. 61-9542, and includes an indoor heat exchanger temperature sensor 9 and an indoor temperature sensor 10 each comprising the thermistor. constitutes a bridge circuit together with two other resistors, and these two signals are given to the differential amplifier 19, and the difference between the two signals is extracted, and it is determined whether or not the outdoor heat exchanger 3 requires defrosting. A judgment is made. If frost forms on the outdoor heat exchanger 8, the counter 20
The counter 20 counts the pulses from the time base 21 and outputs a defrost signal (forced defrost command) until a predetermined value is reached.

This defrost signal is sent from the auxiliary frost detection means 16 to the defrost control means 15, and the defrost operation by the defrost control means 15 is performed while the counter 20 is counting.

FIG. 4 shows the control flow of the indoor controller 11° and the outdoor controller 12 regarding the above-mentioned defrosting.

The microcomputer of the outdoor controller 12 on the outdoor unit side reads the defrosting determination temperature detected by the outdoor heat exchanger temperature sensor 8, and the detected temperature is, for example, ±89°C to -
Check whether the temperature is within the normal range of 29°C (step ■). Therefore, this step (2) corresponds to the sensor abnormality determining means 17 described above.

When the detected temperature is within the above normal range, it is determined that there is no sensor abnormality, and the main frost detection means 14 is caused to perform a defrost determination corresponding to the defrost detection means 14 (step ■), where it is determined that defrost is not necessary. If so, continue heating operation (step ■■)
. On the other hand, frost formation is detected by the outdoor heat exchanger temperature sensor 8,
When it is determined that defrosting is necessary, the defrosting control means 15 enters defrosting operation (step ■■), and the main frost detection means 1
Defrosting is performed until the defrosting signal from 4 disappears (step ■■), and when the defrosting is completed, the process returns to step ■. By repeating the above operations, the air conditioner operates when the outdoor heat exchanger temperature sensor 8 is normal.

However, the defrosting determination temperature detected by the outdoor heat exchanger temperature sensor 8 is not normal operation, for example, 90 degrees Celsius or higher, -3
When the temperature is below 0 degrees Celsius, the judgment in step 2, which is an abnormality determining means, becomes YES (abnormality exists), and an abnormality signal indicating that the outdoor heat exchanger temperature sensor 8 is abnormal is serially transmitted to the indoor unit side (step ■).

When the indoor controller 11 on the indoor unit side receives the above-mentioned abnormal signal serially among the various signals serially transmitted from the outdoor unit side, the indoor controller 11 performs step (1), which corresponds to the function of the auxiliary frost detection hand Fffi 16. Step (10
) to (13), and the process is switched to frost formation determination based on the indoor heat exchanger temperature sensor 9 and the indoor temperature sensor 10.

That is, the indoor controller 11 checks the presence or absence of frost based on the indoor heat exchanger temperature sensor 9 and the indoor temperature sensor 10 (step [phase]), and issues a forced heating command to the outdoor unit while no frost has formed yet. Step 0)
When frost formation is detected, a forced defrost command is serially transmitted to the outdoor unit until the end of defrosting by time management or temperature management (step [phase] @@>).

The outdoor unit side sequentially checks whether the signal received serially from the indoor unit side is the above-mentioned forced heating command or forced defrosting command. A frost operation is performed (Step 0 @). When neither the forced heating command nor the forced defrosting command is serially received, the operation of the indoor unit is turned OFF (Step @).

In this way, even if the outdoor heat exchanger temperature sensor fails, the defrost determination based on the outdoor heat exchanger temperature sensor 8 is switched to the frost formation determination based on the indoor heat exchanger temperature sensor 9 and the indoor temperature sensor 10, and the air conditioner heating function is maintained.

After that, when the outdoor heat exchanger temperature sensor 8 is replaced or repaired by a service person, the temperature detected by the sensor abnormality determining means 17 returns to the normal range, and the judgment in step (2) above becomes NO. Returning to the normal defrosting control flow (steps ① to ①) using the function of the frost detection means 14.

In the above embodiment, the auxiliary frost formation detection means 16 is configured to operate based on the temperature detected by the indoor heat exchanger temperature sensor 9 and the indoor temperature sensor 10, but it detects the current of the motor of the compressor 1 and It may also be configured to determine the presence or absence of frost on the outdoor heat exchanger 8.

U Effects of the Invention] As described above, according to the present invention, even when the outdoor heat exchanger temperature sensor is abnormal, the operation of the air conditioner can be continued without stopping the heating operation. Furthermore, the air conditioner can defrost even when the outdoor heat exchanger temperature sensor is abnormal, and can continue to operate until the abnormality is repaired and recovered.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic configuration of an air conditioner according to an embodiment of the present invention, Fig. 2 is a conceptual diagram of its defrosting control device, and Fig. 3 is a diagram showing the circuit configuration of its auxiliary frost detection means. , FIG. 4 is a flowchart of the defrosting control device. In the figure, l is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4
is a pressure reduction device, 5 is an indoor heat exchanger, 6 is an outdoor fan, 7 is an indoor fan, 8 is an external heat exchanger temperature sensor, 9 is an indoor heat exchanger temperature sensor, 10 is an indoor temperature sensor, 11 is an outdoor controller, 1
2 is an indoor controller, 13 is a room temperature setting device, 14 is a main frost detection means, 15 is a defrost control means, 16 is an auxiliary frost detection means,
17 is an abnormality determining means, 18 is a sensor abnormality handling means, one is a differential amplifier, 20 is a counter, and 21 is a time base. Figure 1 Figure 3

Claims (1)

[Claims] 1. The outdoor unit includes a main frost detection means that determines frost formation when the temperature detected by the outdoor heat exchanger temperature sensor is below a reference value and outputs a defrost signal, and causes the outdoor unit to perform defrosting operation in response to this defrost signal. The indoor unit is provided with an auxiliary frost detection means that indirectly determines the presence or absence of frost on the outdoor heat exchanger and outputs a defrost signal, and an auxiliary frost detection means that detects an abnormality of the outdoor heat exchanger temperature sensor. When the abnormality determining means determines that there is an abnormality in the outdoor heat exchanger temperature sensor, an auxiliary frosting detecting means is selected instead of the main frosting detecting means, and an auxiliary frosting detecting means is selected. An air conditioner comprising sensor abnormality response means for operating the defrosting control means in response to a defrosting signal.