JPS6129666A - Air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an air conditioner equipped with a pressure reducing device with a pressure reducing valve drive unit that can change the amount of pressure reduction by an electric signal for pressure reduction control.

<Prior Art> As shown in FIG. 1, a conventional air conditioner includes an electric compressor 1, a condenser 2, a refrigerant pressure reduction device 3, an evaporator 4, and a refrigerant flow rate control device 5 for the refrigerant pressure reduction device 3. Ta. The pressure reducing device 3 is known to include a pressure reducing device driving section 3B that drives the pressure reducing valve 3A by combining an electric motor, a solenoid, or a heater and a bimetal. Then, a control device is provided so that the difference SH between the inlet temperature and the outlet temperature of the evaporator 4, which is detected by the first and second temperature detectors 5A and 5B provided at the inlet and outlet of the evaporator 4, becomes an appropriate value. 5 outputs an electric signal to the refrigerant pressure reducing device 3 to change the amount of pressure reduction. FIG. 2 shows the relationship between the head 11 of the pressure reducing valve 3A of the refrigerant pressure reducing device 3 and the rotation angle θ of the stepping motor that drives the pressure reducing valve 3A.

FIG. 3 is an example of the control device 5, which includes first and second temperature detectors SA for detecting the temperature at the inlet and outlet of the evaporator 4.
, 5B, an A/D converter 5C that converts the outputs of the temperature detectors 5A and 5B into digital quantities, and an output signal of the A/D converter 5C to convert the temperature difference Sl (to an appropriate value (hereinafter referred to as a target value). a control circuit (microcomputer) 5D that outputs an electrical signal to the refrigerant pressure reducing device 3 to maintain the refrigerant pressure reducing device 3 at SHO (referred to as the value);
The calculation result output from the control circuit 5D is sent to the refrigerant pressure reducing device 3.
It is composed of an output converter 5E that outputs an output in accordance with the output.

However, if there is a shortage of refrigerant in the air conditioner due to some kind of abnormality, such as a pipe leak, the flow rate will not be within the controllable range of the pressure reducing device 3, so the control device 5 will not operate as described above. Despite this, the temperature difference SH cannot be maintained near the target value 5) (0, and the degree of superheat of the refrigerant sucked into the electric compressor 1 continues to be abnormally high. This will lead to several abnormal temperature rises.

In addition, even if the pressure reducing device 3 stops operating due to disconnection or mechanical failure, the degree of superheat of the refrigerant sucked into the electric compressor 1 may remain abnormally high, or the refrigerant may remain in a liquid state. In the former case, there will be an abnormal temperature rise in the electric compressor 1, and in the latter case, the electric compressor 1 will be damaged (this may cause damage to the electric compressor).If the air conditioner is normal, is there any problem in using the conventional control device 5? If the above-mentioned abnormality were to occur, there was a possibility that an even more fatal abnormality would occur if the conventional method were used.

Purpose The present invention has been made to eliminate these drawbacks, and provides an air conditioner that can reliably detect abnormalities in the refrigerant compression cycle simply by adding new components to the program. This is what we are trying to provide.

<Embodiment> An embodiment of the present invention will be described in detail below. A condenser 2 is connected to an electric compressor 1 via piping, and an evaporator 4 is connected to the condenser 2 via a refrigerant pressure reduction device 3. The compressor 1 is connected to the evaporator 4 by piping to form a refrigerant compression cycle, and a control device 10 is provided for maintaining the refrigerant compression cycle in an optimal state. Outputting an electric signal to the refrigerant pressure reducing device 3 to control the valve opening of the pressure forming valve according to the state of the cycle;
If the refrigerant compression cycle cannot be optimized despite the output operation of the electric signal, the blade is configured to output an abnormal signal.

That is, the control device 10 is provided with a first temperature sensor 5A on the inlet side of the evaporator 4, a second temperature sensor 5B on the outlet side of the evaporator 4, and a second temperature sensor 5B on the inlet side of the evaporator 4. A control circuit (microcomputer) 5D that outputs a pressure reduction control signal to the pressure reduction valve drive unit 3B of the pressure reduction device 3 to maintain the temperature difference SH between the temperature TH1 and the outlet temperature TH2 at a temperature difference target value SHO that brings the optimum refrigerant compression cycle state. is provided, and the control circuit 5D has a built-in timer (not shown), and the control circuit 5D has a built-in timer (not shown) to determine whether the deviation of the temperature difference S)I from the target value SHO exceeds the allowable value Δ5l-1 or Δ5HI2. If the condition continues for a predetermined time fT), an abnormality signal is output.

As shown in FIG. 4, this control device 10 includes the first and second temperature detectors 5A and 5B, and an A/D converter that converts the outputs of both temperature detectors 5A and 5B into digital quantities. 5
From the output of the A/D converter 5C and the output of the A/D converter 5C, the refrigerant pressure reducing device 3 is controlled to maintain the temperature difference SH at an appropriate temperature difference SH('l), and the air conditioner (detects any abnormality and sends an abnormality signal). It is composed of a control circuit (microcomputer) 5D having an output terminal 5F for output, and an output converter 5E for outputting the calculation result from the control circuit 5D in accordance with the pressure reducing device 3.

Next, a method for detecting an abnormality in the air conditioner will be explained. First, FIG. 5 shows the change in the temperature difference SH when there is a shortage in the amount of refrigerant IA sealed in the @ cycle of the air conditioner. Changes when normal refrigerant 1j large amount is SHl
It is expressed as, (,' the change when the amount of inclusion is 6()% is SH2, and the change when the amount of inclusion is 2()% is SH3)
, ()%, respectively, are expressed as SH4].

As is clear from FIG. 5, as the amount of refrigerant enclosed becomes insufficient, it takes time for the temperature difference SH to reach the vicinity of the target temperature difference SHO, and furthermore, if the flow rate control range of the refrigerant pressure reduction device 3 is exceeded, , S H3, S I (temperature difference S as in 4)
H never reaches near the target temperature difference SHO.

However, in this case, it can be recognized that the amount of refrigerant enclosed is insufficient when the dog state continues for more than one time based on the allowable deviation value ΔSHh.

Next, a method of detecting when the refrigerant pressure reducing device 3 malfunctions and stops moving from a certain valve lift 11 will be described. FIG. 6 shows the relationship between the temperature difference S)I in the steady state of the refrigerant compression cycle when the valve head is 11.

If the refrigerant pressure reduction device 3 is insufficiently depressurized and the refrigerant pressure reduction device 3 is insufficiently depressurized, liquid refrigerant flows into the electric compressor 1. If this continues, the electric compressor 1 may be damaged.

At this point, the temperature difference SKI continues to be at the temperature difference SH5 shown in FIG. The deviation ΔSH from the target temperature difference SHO is monitored. A malfunction of the refrigerant pressure reducing device 3 can be detected when the deviation ΔSH exceeds the allowable deviation value ΔSHρ for a predetermined time T or more.

In addition, if the valve head 11 is too small as in 112 and malfunctions thereafter, the amount of pressure reduction in the pressure reducing device 3 becomes too large, causing gaseous refrigerant with a high degree of superheat to be sucked into the electric compressor 1. From this, it is clear that the situation is equivalent to the above-mentioned situation where the enclosed refrigerant is insufficient.

Next, the above control method is shown in the flowchart of FIG. , and if so, determine whether the exceeding time Tan or the control circuit (
A timer in the microcomputer (SD) determines whether the predetermined time T has elapsed. Then, if the predetermined time T has been exceeded, an abnormality signal is output, and a calculation for controlling the pressure reducing device 3 is performed and output in the control side path 5D.

In addition, if the temperature difference SH does not exceed the deviation tolerance value ΔSH1+ with respect to the target temperature difference SHO, then it is determined whether or not the temperature difference SH exceeds the deviation tolerance value ΔSHρ with respect to the target temperature difference SHO, and the tolerance value If it is not within Δ5l-1ρ, the pressure reducing device is controlled in the same order as above.

If the value is within the allowable value ΔSH, the timer is reset and then normal control of the pressure reducing valve is performed.

Note that, as a method for this control device 10 to control the refrigerant pressure reducing device 3, for example, when the temperature difference SH increases in response to a change in the temperature difference SH, the valve lift 1 of the refrigerant pressure reducing device 3 is changed.
1 is increased, and when the temperature difference SH decreases, b (this is so-called proportional control that outputs a control electric signal to decrease the valve head 11 of the pressure reducing device 3, and the temperature difference S) l and the target value S
To correct the deviation from HO, for example, calculate the deviation at regular intervals and if it is outside the allowable range, the deviation I
The combination with so-called integral control, which outputs a control electric signal that changes the valve lift () in a direction that corrects the valve head ()), is highly recommended.

<Effects> As is clear from the above description, the present invention provides an air conditioner in which a refrigerant compression cycle that circulates refrigerant is provided with a refrigerant decompression device that changes the flow rate of refrigerant, and that maintains the refrigerant compression cycle in an optimal state. A control device is provided for controlling the valve opening of the pressure reducing valve of the refrigerant pressure reducing device according to the state of the refrigerant compression cycle, and the control device outputs an electric signal for controlling the valve opening of the pressure reducing valve, and controls the output operation of the electric signal. However, if the refrigerant compression cycle cannot be optimized, an abnormality signal is output.

Therefore, according to the present invention, by adding a simple program, failures such as insufficient amount of refrigerant in the refrigerant compression cycle or malfunction of the pressure reducing device can be detected before other components are fatally damaged. It is very effective and practical.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional air conditioner, Fig. 2 is a diagram showing the relationship between the rotation angle θ of the stepping motor for driving the pressure regulating valve and the lift height 11 of the pressure reducing valve, and Fig. 4 is an air conditioner according to the present invention. FIG. 5 is a diagram showing the temperature difference depending on the amount of refrigerant 11, FIG. 6 is a diagram showing the temperature difference for different valve lifts 11, and FIG. 7 is a control flowchart of the same. 1: Electric compressor, 2: Condenser, 3: Refrigerant pressure reduction device generator,
5A, 5B: Temperature detector, 5D two control circuits, 5E: Output converter, 5F: Abnormal signal output terminal, 10: Control device.

Claims (1)

[Claims] In an air conditioner that is equipped with a refrigerant pressure reduction device that changes the flow rate of refrigerant in a refrigerant compression cycle that circulates refrigerant,
A control device for maintaining the refrigerant compression cycle in an optimal state is provided, and the control device outputs an electric signal to the refrigerant pressure reduction device to control the valve opening of the pressure reduction valve according to the state of the refrigerant compression cycle. The air conditioner is further configured to output an abnormal signal when the refrigerant compression cycle cannot be optimized despite the output operation of the electric signal.