JPS636351A - Trouble detector for electric expansion valve of 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 <Industrial Application Field> The present invention relates to a failure detection device for an i-dynamic expansion valve in an air conditioner incorporating a compressor driven by an inverter that makes frequency variable.

(Prior Art) Conventionally, a compressor (1) and an inverter (1a) that adjusts the capacity by varying the operating frequency of the compressor R (1) and an opening degree according to the capacity of the compressor (1) have been used. An air conditioner is known that is equipped with a variable electric expansion valve (5) and whose capacity is controlled (see Japanese Patent Laid-Open No. 58-205057).

(Problems to be Solved by the Invention) By the way, in such an air conditioner, if a failure occurs in the drive electronic circuit of the electric expansion valve or a failure due to disconnection of the electric line, an abnormality occurs in the control of the electric expansion valve. However, no suitable method has been found to reliably detect malfunctions of the electric expansion valve body due to defects in the electric expansion valve body or foreign matter contamination.

For example, if the electric expansion valve stops working at a small opening due to chips mixed in during machining, foreign objects mixed in during assembly, or foreign objects mixed in the lubricant, there may be a lack of air conditioning capacity, or the indoor coil gets stuck especially during cooling. It is relatively easy to detect because frost forms, but if the compressor stops working at a large opening, there is a risk that the refrigerant liquid will flow into the compressor by the time the abnormality is detected, causing damage to the compressor due to liquid compression. arise.

The present invention has been made in view of the above points, and its purpose is to change the state of the refrigerant f before and after the electric expansion valve is throttled during high-capacity operation of the compressor. Focusing on this, the objective is to reliably detect failure of the electric expansion valve from the value of the change in the state quantity and prevent damage to the compressor.

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention, as shown in FIG. 1, makes the compressor (1) and its operating frequency variable. Inverter (1a) that adjusts its capacity
) and an electric expansion valve (5). A failure detection device for the electric expansion valve of such an air conditioner includes a high capacity detection means (11) for detecting when the capacity of the compression 1ff (1) is higher than a set value, and the high capacity detection means. Compressor (1) detected in (11)
control means (1) for controlling the capacity adjustment of the compressor (1) by the inverter (1a) to be fixed and to greatly reduce the opening degree of the electric expansion valve (5) during high capacity operation of the compressor (1);
2), a state quantity detection means (TH2) which receives the output of the control means (12) and detects the state quantity of the refrigerant before and after the change in the opening degree of the electric expansion valve (5), and the state quantity detection means (TH2); T
The present invention also includes a determining means (13) that outputs a failure signal when the change in the state quantity detected in step H2) is less than a set value.

(Function) With the above configuration, in the present invention, the operation period when the capacity of the compressor (1) becomes higher than the set value is determined by the high capacity detection means (11).
), the control means that receives the signal from the high capacity detection means (11) fixes the operation of the pressure control device (1) in that state, and also controls the electric expansion valve (5). )
The opening degree is greatly reduced. At this time, when the operation of the electric expansion valve (5) is normally throttled, the state quantity of the refrigerant changes by more than the set value before and after the change in the electric expansion valve (5), and this is detected by the determining means (13). ) is determined to be normal.

- On the other hand, if the opening degree is not throttled due to a failure of the electric expansion valve (5) and the state quantity does not change by more than the set value, the determination means (13) determines that the electric expansion valve (5) is malfunctioning. A failure of the compressor (1) is detected, and damage to the compressor (1) due to malfunction, especially in a state where the opening degree is large, is effectively prevented.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings from FIG. 2 onwards.

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied, (A) is an outdoor unit, (B) is an indoor unit, and the outdoor unit (A) has a variable frequency. A compressor (1) whose capacity is adjusted by an inverter (1a), a four-way selector valve (2) which switches as shown by the solid line in Figure 2 during heating operation and a broken line during cooling operation, and an accumulator (3). ) and outdoor heat exchanger (
4) and an electric expansion valve (5) that adjusts the refrigerant flow rate as the main equipment, and the indoor unit (B) is equipped with an indoor heat exchanger (6) as the main equipment. Major I! The refrigerant pipes are connected to each other by refrigerant pipes (8).

Further, (T[→1) is a room temperature thermostat disposed in the main body casing of the indoor unit (B), and (10) is a control unit of the air conditioner.

During heating operation, the flow of refrigerant is as shown by the solid arrow,
The refrigerant discharged from the compressor (1) is transferred to the indoor heat exchanger (6)
After undergoing heat exchange, it is throttled by the electric expansion valve (5), vaporized in the outdoor heat exchanger (4), and compressed again through the accumulator (3)! It is refluxed to ff(1). In the above refrigerant flow, the control unit (10), in accordance with the deviation signal between the indoor temperature and the set temperature input from the room temperature thermostat (THI),
It outputs a frequency signal that adjusts the frequency of the inverter (1a), and also outputs a pulse signal that adjusts the opening degree of the electric ljJ expansion valve (5) according to the value f of the frequency signal.

Table 1 below shows the relationship between the frequency signal value f and the pulse signal value N. The upper row shows the frequency signal value f of the inverter (1a), and the middle row shows the frequency signal value f during heating operation. The output pulse signal value N, the lower row is the pulse signal value N output during cooling operation, both of which are configured to increase as the frequency signal value increases.

Table 1 Next, the capacity M of the compressor (1) is controlled by the inverter (1a) which varies the output frequency according to the frequency signal, while the electric expansion valve ( 5) changes the opening degree as shown in the graph of FIG. In the graph of FIG. 3, the horizontal axis is the pulse signal value N input to the electric expansion valve (5), the vertical axis is the opening degree of the electric expansion valve (5), and as the pulse signal value N increases, The opening degree increases almost linearly,
The outdoor heat exchanger (4) depends on the opening degree of the electric expansion valve (5).
The refrigerant evaporation temperature at is adjusted to an appropriate range. According to the above procedure, the compression 1
The capacity of m(1) is appropriately controlled.

Above, we have explained the heating operation, but in the cooling operation, the flow of refrigerant is as shown by the broken line arrow in Figure 2.
Similarly to the above, the capacity of the compressor (1) is appropriately controlled according to the load on the indoor unit (B).

Furthermore, in FIG. 2, (TH2> is the compressor (1
) is a temperature sensor which is a refrigerant state quantity detection means disposed on the suction pipe side of the refrigerant, and the temperature sensor is configured to detect the refrigerant temperature T.
e is detected and outputs a refrigerant humidity value signal. The graphs in Fig. 4 (a) and (b) show that during heating operation, the frequency of the inverter (1a) is fixed, and the opening degree of the wv'J expansion valve (5) is changed by changing the above-mentioned pulse signal value. TH2 indicates the value of the temperature Te of the refrigerant detected by the temperature sensor (TH2) when
Fig. 4 (a) shows the case when the frequency is 90H2, and Fig. 4 (b) shows the case when the frequency is 30H2. As shown in FIGS. 4(a) and 4(b), when the frequency f is large, that is, the operating capacity of the compressor (1) is large, the refrigerant temperature that occurs when the opening degree of the electric expansion valve (5) is reduced When the increase in F is large (the degree of superheating of the refrigerant becomes large) and the frequency f is small, that is, the operating capacity of the compressor (1) is small, the refrigerant temperature will hardly change even if the opening of the electric expansion valve (5) is reduced. do not. Therefore, when the frequency f is large to a certain extent, by outputting a pulse signal that reduces the opening degree of the electric expansion valve (5) and detecting the change in refrigerant temperature at that time, the electric expansion valve (5) can be operated normally. It can be determined whether or not. Although the explanation has been given above regarding the heating operation, the same applies to the cooling operation.

Figure 5 shows the room temperature thermostat (THI) during normal operation.
) shows an example of a change in the frequency f of the inverter (1a) that is controlled according to the load signal of the indoor unit (B) from Indicates the lower limit of f, and in this example f=70H
z, and when f>70 for 2 consecutive minutes, it is determined that the indoor load is sufficiently large and a check operation is started. Moreover, the broken line of time tB indicates the initial setting time until the compressor (1) is continuously operated and stabilized, and is set to 30 minutes in this embodiment.

Based on the above considerations, a check operation procedure for detecting failure of the electric expansion valve (5) will be explained with reference to the flowchart of FIG.

In the flowchart of FIG. 6, first in step S1 it is determined whether the compressor (1) is started for the first time.

However, if No, the check operation has already been completed, and the process proceeds to step S2, normal operation; if YES, the process proceeds to step S2.
Move to 3. In step S3, it is determined whether or not the initial setting time t = 30 (minutes) shown in FIG. 5 has elapsed, and when 30 minutes have elapsed (YES), the process moves to step S4. Next, in step S4, as shown in the graph of FIG.
It is determined whether the indoor load is continuously large for several minutes, and when YES is determined that the indoor load is sufficiently large, the process moves to step S5 and an abnormality determination procedure is entered.

In this abnormality determination procedure, first in step S5, the load signal of the indoor unit (B) input from the room temperature thermostat (T!-11) is ignored as shown in the graph of FIG. Then, in step S6, the refrigerant temperature Te detected by the temperature sensor (TH2) at this time is set to Te+. Furthermore, immediately in step S7, the pulse signal value N is forced to rO as shown in FIG. 7(0).
command to reduce the opening of the electric #J expansion valve (5) to "0". Next, in step S8, the refrigerant temperature Te is measured again, and in step S9, it is determined whether the change value from TO+ to Te (Te −7e I) is smaller than the abnormality determination value Δ°C of the electric expansion valve (5). Determine. here,
As shown in FIG. 7(C), the judgment value Δt is the electric expansion valve (5) with respect to the refrigerant temperature Te+ at time t1 when the pulse signal value N is changed to "0". This is the lower limit of the change value of the refrigerant temperature Te that would naturally occur if the opening is restricted to rOJ in normal operation, and is determined by the capacity of the air conditioner, the installation condition, etc. Step S9
If the change value (Te − Te + ) is greater than or equal to the determination value Δ (No), it is determined that the electric expansion valve (5) is normal, and the process proceeds to step S2, whereupon normal operation begins. - On the other hand, the change value (Te-Te1) changes to the judgment value t
If the answer is YES, the process moves to step S10.

In step S IQ, as shown in Figure 7 (a), the time to maintain the frequency f at a constant value is set to 3 minutes, which does not have a negative effect on the air temperature or air conditioner, and the frequency f is maintained at a constant value for 3 minutes. After repeating the above steps S8 and Ss for 3 minutes from time to, which is maintained at a constant value,
If the determination in step S9 is still YES after three minutes have elapsed, the process moves to step S11.

In step Sn, it is determined whether or not the abnormality determination procedure of the electric expansion valve (5) has been performed three times in accordance with the procedure from step 84 to S barrel of -F, and if NO, step 31 is performed.
2 and -H frequency f fixed and electric expansion valve (5
) is released from the fixation of the pulse signal value N-0 that commands the throttle opening of Proceeding to S4, the abnormality determination procedure for the electric expansion valve (5) in steps S4 to S1o is executed again in the same manner as above. Then, even if the abnormality determination procedure of steps 84 to S10 is executed three times, if the change value (Te − Te l ) of the refrigerant temperature Te is smaller than the determination value Δt and the determination in step S10 is YES,
A failure signal indicating that the electric expansion valve (5) is abnormal is output, and the air conditioner is stopped.

As described above, in this embodiment, the high capacity detection means (1) detects the high capacity operation of the compressor (1) in step S4.
1) is configured, and the high capacity state of the compressor (1) is fixed by steps S5 and Ss, and the electric expansion valve (
A control means (12) is configured to control the opening degree of 5) to be narrowed down.

Also, step S9. SIO and 8u determine the electric expansion valve (5) from the magnitude of the change in evaporation temperature (Te Te l ) before and after the opening of the electric expansion valve (5) is throttled, which is detected by the state quantity detection means (TH2). 5)
Discrimination means (13) for determining the presence or absence of a failure is configured.

Therefore, in the above embodiment, after the operation of the compressor (1) becomes stable, when the load on the indoor unit (B) increases and the compressor (1) starts to maintain high capacity operation, the compression The increase in pulse signal value N is forcibly set to N-0 so that the opening degree of the electric expansion valve (5) increases as the capacity of the motor (1) increases. If the operation is normal, the refrigerant temperature r! will be observed as the pulse signal value N changes as shown in Fig. 4 (a). Failure of the electric expansion valve (5) can be determined based on the presence or absence of an increase in ITe. That is, when the change value of the refrigerant temperature Te is smaller than Δt, either the electric expansion valve (5) remains open at a large opening and does not close, or the culm opens at a small opening and does not close. There are two ways to do this, so in either case, a failure condition has been detected in which the electric expansion valve (5) has stopped operating due to a foreign object, etc., and if the operation continues, especially when the opening is large, the compressor (1) effectively prevents damage. In addition, in step So, the abnormality determination procedure is repeated three times, so when no rise in refrigerant temperature Te is observed due to some other incidental cause other than a failure in the electric expansion valve (5), the electric expansion valve (5) ) is effectively prevented from being mistakenly determined as a failure.

It is known from experience that malfunctions of the electric expansion valve (5) due to foreign objects, etc. almost always occur immediately after the start of operation.
The failure check operation of the 'FFi dynamic expansion valve (5) according to the above abnormality determination procedure is carried out after starting the compressor (
It is effective to carry out step 1) once a day when the operation is stable, but the number and timing of the step can be arbitrarily determined depending on the weight of the air conditioner, the installation condition, etc.

Furthermore, although the above embodiment describes an example in which a single indoor unit (B) is connected to an outdoor unit (A), the same applies to a multi-type air conditioner in which a plurality of indoor units are connected. .

Furthermore, in this embodiment, a temperature sensor as a means for detecting the state quantity of the refrigerant is attached to the suction pipe of the compressor to detect changes in the temperature of the suction gas, but instead of the temperature sensor, a pressure sensor is used. A change in pressure (a change in temperature when a change in pressure is converted into a change in temperature) may be detected.

In addition, the temperature sensor can be installed at any location, regardless of the suction pipe.
It may be attached to an indoor heat exchanger or an outdoor heat exchanger, and in this case, changes in the evaporation temperature (saturation temperature) of the refrigerant may be detected.

In addition to setting the opening degree for each frequency as in this embodiment, the electric expansion valve (5) also detects the degree of superheat at the outlet of the heat exchanger that serves as the evaporator, and keeps this degree of superheat constant. Electric vJ1B whose opening is controlled so that It can also be Zhang Ben.

(Effects of the Invention) As explained above, according to the present invention, when the compressor is operating at a high capacity, the opening degree of the electric expansion valve is reduced while maintaining the high-level ω operation state, and the change in the opening degree is suppressed. Since the abnormality of the electric expansion valve is determined based on the magnitude of the change in the refrigerant temperature Te before and after, it is possible to detect failures of the electric expansion valve, and to detect malfunctions caused by foreign objects, etc., especially when the opening degree is large. can be reliably detected, and damage to the compressor due to malfunction of the 1Fi cost expansion valve can be effectively prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 7 show examples of the present invention, FIG. 2 is a refrigerant piping system diagram, and FIG. 3 is a graph showing the relationship between the opening degree of the electric expansion valve (5) and the pulse signal ia N. , Figure 4 (a)
and (b), the frequency f is 90H2 and 30H2, respectively.
Figure 5 is a graph showing changes in refrigerant temperature Te with respect to pulse signal value N during heating when fixed at H7; Figure 5 is a graph showing changes in frequency f with respect to time during operation;
The figure is a flowchart showing the check operation procedure for detecting failure of the electric expansion valve (5), and Figures 7 (a), (b), and (c) show the frequency f with respect to the change in IJt during abnormal check operation, respectively. , is a graph showing changes in pulse signal ffflN and refrigerant temperature Te. (1)...Compressor, (1a)...Inverter, (5
)...Electric expansion valve, (11)...High capacity detection means,
(12)...Plate control means, (13)...Discrimination means, (
TH2)...Temperature sensor (state quantity detection means). Published = Noodles = Knee - Patent applicant: Daikin Industries, Ltd. r+1'3
i:,'F"j゛. ・-3" ′-゛,. Before the agent 1)
Hiro Ni, 4. ,, □'・-shi+1-～- Figure 3 Figure 5 (b) Figure 4 Bannon's number A through N Figure 7 Time t f Darkness t

Claims (1)

[Claims] (1) In an air conditioner comprising a compressor (1), an inverter (1a) that adjusts the capacity of the compressor (1) by varying its operating frequency, and an electric expansion valve (5), the compressor A high capacity detection means (11) detects when the capacity of the compressor (1) is operating at a set value or higher; a control means (12) for controlling the capacity adjustment of the compressor (1) by the control means (1a) so as to fix the capacity adjustment of the compressor (1) and to greatly reduce the opening degree of the electric expansion valve (5); 5) A state quantity detection means (TH2) that detects the state quantity of the refrigerant before and after the opening change, and outputs a failure signal when the change in the state quantity detected by the state quantity detection means (TH2) is less than a set value. What is claimed is: 1. A failure detection device for an electric expansion valve of an air conditioner, characterized in that the device comprises: a determining means (13) for detecting a failure.