JP2005069683A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner provided with a compressor driven by an inverter system, ensure the reliability of the compressor and enable accurate failure diagnosis of an electronic controlled expansion valve at the time of service. <P>SOLUTION: This is an air conditioner wherein a compressor, an indoor side heat exchanger, an electronic controlled expansion valve and an outdoor side heat exchanger constitute a refrigerating cycle, and the compressor is driven by an inverter system. This air conditioner is configured to change the maximum frequency of the compressor in the case where the discharge temperature of the compressor is abnormally reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an air conditioner including a compressor driven by an inverter, and relates to an air conditioner in which the amount of refrigerant is controlled by an electronically controlled expansion valve.

  A technique is disclosed in which the pressure reducing valve 4 is controlled by detecting a reversal of the inclination in a temporal change in the inlet / outlet temperature difference of the indoor heat exchanger. (For example, see Patent Document 1)

Further, the opening degree of the expansion valve 4 corresponding to the operating frequency is set, and a valve opening degree command signal corresponding to the temperature difference detected by the middle of the indoor heat exchanger 5 and the outlet temperature detection sensor is output. A technique for adjusting the opening is disclosed. (For example, see Patent Document 2)
Japanese Unexamined Patent Publication No. 60-11075 JP 58-205057 A

In an air conditioner in which conventional refrigerant flow control is performed by a decompression device, if the decompression device fails, the phenomenon of a liquid back where the compressor sucks liquid refrigerant may occur depending on the position of the decompression valve at the time of failure. This caused problems with the reliability of the compressor.
In addition, there is a problem that the failure of the electronically controlled expansion valve cannot be grasped only by the operating state at the time of service.

  The present invention has been made to solve the above-described problems, and aims to ensure the reliability of the compressor.

  It is also aimed at accurate fault diagnosis of electronically controlled expansion valves during service.

  An air conditioner according to the present invention includes a compressor, an indoor heat exchanger, an electronically controlled expansion valve, and an outdoor heat exchanger that constitute a refrigeration cycle, and the compressor is inverter-driven. When the temperature drops abnormally, the maximum frequency of the compressor is changed.

  An air conditioner according to the present invention includes a compressor, an indoor heat exchanger, an electronically controlled expansion valve, and an outdoor heat exchanger that constitute a refrigeration cycle, and the compressor is inverter-driven. Since the maximum frequency of the compressor is changed when the temperature is abnormally lowered, there is an effect of avoiding a risk that the compressor breaks down.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a refrigeration cycle according to Embodiment 1 of the present invention. 1 is a compressor, 2 is an electric motor, 3 is an outdoor heat exchanger, 4 is an electronically controlled expansion valve, and 5 is an indoor heat exchanger. 6 is a frequency variable device, 7 is a control device, 8 is a thermistor that detects the discharge temperature of the compressor 1, 9 is a thermistor that detects the inlet temperature of the indoor heat exchanger 5, and 10 is the middle of the indoor heat exchanger 5. This is a thermistor that detects temperature. In addition, the control device 7 includes a control unit 71 that controls a storage function, a calculation function, and these functions based on input signals from the discharge temperature detection thermistor 8, the inlet temperature detection thermistor 9, and the intermediate temperature detection thermistor 10, and the control unit 71. The valve drive unit 72 operates the electronically controlled expansion valve 4 based on the output signal (valve opening command signal).

  Next, the operation of the air conditioner according to Embodiment 1 of the present invention will be described in detail. If the rotation speed of the compressor 1 is changed by controlling the frequency by the frequency variable device, the air conditioning capacity of the air conditioner can be changed approximately proportionally as shown in FIG. Therefore, when the output frequency of the frequency variable device 6 is changed to, for example, 100 steps as shown in FIGS. 3 and 4, when 10 frequency bands are provided for every 10 steps among the 100 steps, the frequency band is set. Then, the compressor 1 is rotated to obtain the optimum expansion valve opening (PULn) and the optimum discharge temperature (TDn) at that time by experiments, etc., and the optimum expansion valve opening (PULn) and optimum discharge for each frequency band are obtained. The temperature (TDn) is stored in the control unit 71 in advance. When the output frequency of the frequency variable device 6 changes, the optimum valve opening (PULn) corresponding to the changed frequency is selected by the control unit 71, and the valve opening command signal corresponding to the selected value is controlled. The opening degree of the electronically controlled expansion valve 4 is controlled so as to match the target value via the valve drive unit 72 output from the unit 71. Next, after a predetermined time (for example, several minutes) has passed and the cycle is stabilized, the control unit 71 determines the deviation amount between the discharge temperature and the set discharge temperature (TDn) in the current frequency band based on the detection signal from the thermistor 8. A valve opening command signal corresponding to the calculated deviation amount is output. The electronically controlled expansion valve is adjusted based on this output signal, and the refrigerant flow rate is controlled according to the load fluctuation. The refrigerant flow rate is controlled as described above.

  With only the control of the refrigerant flow rate as described above (same as in the above prior art), the optimum discharge temperature (superheat amount in the above prior art) changes when there is a large load fluctuation or when the refrigerant is insufficient, etc. In the inner heat exchanger, the superheated steam region advances from the outlet toward the inlet with respect to the direction in which the refrigerant flows, or partially appears at a substantially intermediate position. For this reason, moist air enters the indoor heat exchanger portion of the superheated steam region, causing a phenomenon of dew dripping from the outlet and dew splattering.

  Therefore, in the first embodiment of the present invention, in addition to the refrigerant flow rate control described above, a thermistor 9 is installed at the inlet of the indoor heat exchanger during cooling operation, and the thermistor 10 is installed approximately in the middle in order to detect the phenomenon ( For example, in the case of two rows of heat exchangers as shown in FIGS. 5 (a) and 5 (b), the superheated steam region basically advances from the outlet direction to the inlet direction, and wraps around from the second row to the first row. However, if the superheated steam area stops at the second row and does not advance to the first row, the moist air in the first row is dehumidified and the moist air does not enter the air conditioner.・ Dew dripping cannot occur.The sensor position is not at the exit, but at a substantially intermediate position.The point where the degree of superheat is the largest due to heat exchange in the first and second rows, imbalance in the wind speed distribution, etc. This is because there is no limit. For example, the position is as shown in Fig. 5 (a) and Fig. 5 (b) because it is necessary to be a position that does not wrap around the superheated steam region in the first row at least. The experiment is performed under the condition that the above phenomenon is likely to occur, and the temperature difference (TH10−TH9 = ΔTH10−9) between the thermistor 9 and the thermistor 10 is more than (ΔTHk10−9), Also, the number of minutes (Tk) when the above phenomenon occurs and the target discharge temperature is lowered to how many times (that is, the expansion valve is in the direction of increasing the flow rate in the opening direction and in the direction of decreasing the overheating region). 4) Whether the above phenomenon is eliminated is obtained for each frequency band (TDk) as shown in FIG. 4, and each value is stored in the control unit 71. The temperature difference ΔTH10-9 is always detected during the refrigerant flow rate control, and the value is equal to or greater than the value (ΔTHk10-9) stored in the control unit 71, and the time (Tk) stored in the control unit continues. Then, the target discharge temperature is changed from TDn to TDk, and the controller 71 determines the deviation amount (ΔTH10-9−ΔTHk10-9) between the current temperature difference (ΔTH10-9) and the set temperature difference (ΔTHk10-9) and the thermistor. 8 calculates a deviation amount (TD-TDk) between the current discharge temperature (TD) detected from 8 and the set discharge temperature (TDk) after the change, and outputs a valve opening signal corresponding to the calculated deviation amount (TD-TDk). The controlled expansion valve 4 is adjusted in the opening direction to avoid the above phenomenon.

  FIG. 6 is a flowchart showing a program of the control unit 71. That is, the output frequency signal of the frequency variable device 6 is input to the block 711 of the control unit 71, and the process proceeds to block 712. In block 712, the temperature detection signals of the discharge temperature detection thermistor 8, the inlet temperature detection thermistor 9, and the intermediate temperature detection thermistor 10 are input, and the flow proceeds to block 713. In block 713, an optimum valve solution value (PULn) corresponding to the frequency is selected, and the process proceeds to block 714. In block 714, the set discharge temperature corresponding to the frequency is selected from TDn and TDk, and the process goes to block 715. In block 715, the control opening degree of the expansion valve 4 is set (the optimum valve opening degree (PULn) + the corrected valve solution degree (ΔPUL) described below), and a valve opening degree command signal corresponding thereto is output. Based on the output signal, the opening degree of the electronically controlled expansion valve 4 is adjusted. In block 716, the cycle stabilization time (Tb) is counted. If it is determined that the time Tb has not elapsed, the process returns to block 711. If it is determined that the time Tb has elapsed, the process proceeds to block 717. In block 717, the deviation amount (TD-TDn or TD-TDk) between the current discharge temperature (TD) detected from the thermistor 8 and the set discharge temperature (TDn or TDk), and the current temperature difference (ΔTH10) detected from the thermistors 9 and 10. -9) and the set temperature difference (ΔTHk10-9) are calculated (ΔTH10-9-ΔTHk10-9). When the set discharge temperature is TDn, the set discharge temperature is calculated from the deviation (TD-TDn). When TDk is TDk, a correction valve opening degree (ΔPUL) corresponding to the deviation amount (TD−TDk) and the deviation amount (ΔTH10-9−ΔTHk10-9) is obtained, and the process returns to block 711.

  FIG. 7 shows details of the block 714. If the current temperature difference (ΔTH10-9) is equal to or greater than the set temperature difference (ΔTHk10-9) and continues for the time (Tk), the set discharge temperature is selected as TDk, otherwise, TDn is selected.

  The first embodiment of the present invention has been described in the case where the refrigerant flow rate control at the normal time is performed at the discharge temperature. However, the temperature difference between the inlet and outlet of the indoor heat exchanger or the substantially middle and outlet is the same as in the past. Even when controlling the flow rate of refrigerant at normal time by detecting the amount of superheat at the top, add another sensor (if the sensor is provided at the inlet and outlet, it is roughly in the middle, and roughly in the middle and outlet Like the above example, the sensor is installed at the inlet) Like the above example, the temperature difference between the sensor and the middle of the sensor is used to detect the risk of dew and dripping. A method of preventing dew stagnation and dripping by opening the valve opening and increasing the refrigerant flow rate to reduce the superheated steam region may be used.

  As described above, in the present invention, by attaching a temperature detection sensor approximately in the middle of the inlet of the indoor heat exchanger and detecting the temperature difference, the humid air is sucked into the indoor unit casing and the air passage wall, Since it is possible to directly detect the superheated steam region of the evaporator in which dew condensation may occur on the blower, the wind direction deflecting plate, and the like, it is possible to reliably prevent dew jumping and dripping.

  Next, the block diagram of the air conditioner by other Embodiment of this invention is shown in FIG. 1 is a compressor, 2 is an electric motor, 3 is an outdoor heat exchanger, 4 is an electronically controlled expansion valve, and 5 is an indoor heat exchanger. 6 is a frequency variable device, 7 is a control device, and 8 is a thermistor. The control device also includes a storage function, an arithmetic function, a control unit 71 that controls these functions, and a valve drive unit 72 that operates the electronically controlled expansion valve 4 based on an output signal (valve opening command signal) of the control unit 71. It consists of.

  Next, the operation of the air conditioner according to another embodiment of the present invention will be described in detail. As shown in FIG. 2, if the frequency of the compressor 1 is changed by frequency control using a frequency variable device, the air conditioning capacity of the air conditioner can be changed approximately proportionally. Therefore, when the output frequency of the frequency variable device 6 is changed to, for example, 100 steps as shown in FIGS. 3 and 4, when 10 frequency bands are provided for every 10 steps among the 100 steps, the frequency band is set. The optimum expansion valve opening (PULn) and the optimum discharge temperature (TDn) at that time are obtained through experiments and the like, and the optimum expansion valve opening (PULn) and optimum for each frequency band The discharge temperature (TDn) is stored in the control unit 71 in advance. When the output frequency of the frequency variable device 6 changes, the optimum valve opening (PULn) corresponding to the changed frequency is selected by the control unit 71, and the valve opening command signal corresponding to the selected value is controlled. The opening degree of the electronically controlled expansion valve 4 is controlled so as to match the target value via the valve drive unit 72 output from the unit 71. Next, after a predetermined time (for example, several minutes) has passed and the cycle is stabilized, the control unit 71 makes a deviation between the discharge temperature and the set discharge temperature (TDn) in the current frequency band based on the detection signal from the temperature detector 8. An amount is calculated and a valve opening command signal corresponding to the deviation is output. The electronically controlled expansion valve is adjusted based on this output signal, and the refrigerant flow rate is controlled according to the load fluctuation. The refrigerant flow rate is controlled as described above.

  In addition to the above refrigerant amount control, in Embodiment 2 of the present invention, when a failure of the electronically controlled expansion valve occurs (for example, mechanical part failure, drive part failure, wiring failure, etc.), the position where the valve stops In some cases, the compressor may be damaged due to the compressor liquid back operation, and in order to prevent this, control is performed to change the maximum frequency of the compressor when it is determined that there is a risk.

Hereinafter, it will be described in detail with reference to the drawings. When the expansion valve 4 is out of order, the discharge temperature (TH8) does not rise even if a signal for closing the expansion valve is output from the control unit 71 to the drive unit 72 in the refrigerant flow control described above. Therefore, depending on the position of the expansion valve at the time of failure, the control unit 71 continues to output a signal in the closing direction without rising to the target discharge temperature.
Therefore, how many Hz (HZ1) and how many minutes (T1) the liquid back operation of the compressor will cause a risk of failure of the compressor. Is determined by reliability experiments or the like, and stored in the control unit 71 in advance. In addition, the discharge temperature (TDl) at which it is determined that the liquid back operation is performed, and the number of pulses or less at which it is determined that the failure has occurred (PUL1) are also stored in the control unit 71 in advance. That is, when the state where TH8 is equal to or less than Tl, the opening degree command signal of the control unit 71 is equal to or less than PUL1, and the operation frequency is equal to or greater than HZ1 during the air conditioning operation, the control unit 71 performs the operation frequency. Is changed to HZg to avoid the risk of compressor failure.

  FIG. 9 is a flowchart showing a program of the control unit 71. That is, in block 710 of the control unit 71, it is determined whether or not the maximum frequency is restricted. When it is determined that the restriction is to be performed, the maximum frequency restriction signal is output to the frequency variable device 6 and, as a result, the rotational speed of the compressor 1 is controlled. In block 711, the output frequency signal of the frequency variable device 6 is input, and the process proceeds to block 712. In block 712, the temperature detection signal of the thermistor 8 is input, and the process proceeds to block 713. In block 713, an optimum valve solution value (PULn) corresponding to the frequency is selected, and the process proceeds to block 714. In block 714, the set discharge temperature (TDn) corresponding to the frequency is selected, and the process proceeds to block 715. In block 715, the control opening degree of the expansion valve 4 is set (the optimum valve opening degree (PULn) + the corrected valve solution degree (ΔPUL) described below), and a valve opening degree command signal corresponding thereto is output. Based on the output signal, the opening degree of the electronically controlled expansion valve 4 is adjusted. In block 716, the cycle stabilization time (Tb) is counted. If it is determined that the time Tb has not elapsed, the process returns to block 710, and if it is determined that the time Tb has elapsed, the process proceeds to block 717. In block 717, a deviation amount (TD−TDn) between the current discharge temperature (TD) detected from the thermistor 8 and the set discharge temperature (TDn) is calculated, and a correction valve opening (ΔPUL) corresponding to the deviation is calculated, and the flow goes to block 710. Return.

  FIG. 10 is a detailed view of block 710. That is, when the temperature (TH8) of the thermistor 8 is TD1 or less, the valve opening command signal is PUL1 or less, and the operating frequency is HZ1 or more, the maximum frequency is regulated to HZg. In other cases, there is no restriction.

  As described above, in another embodiment of the present invention, when a failure occurs in the electronically controlled expansion valve, the compressor may be damaged due to the compressor liquid back operation depending on the position where the valve stops. Therefore, the reliability of the compressor has been successfully improved by estimating the operating state of the compressor from the compressor frequency, valve opening and compressor discharge temperature, and regulating the maximum frequency of the compressor. Yes.

  Note that such a state is not always a failure of the expansion valve, and may occur, for example, when the outside air temperature is very low. Therefore, without stopping the compressor, the compressor vanes jump, the amount of oil taken out from the compressor, the axial load of the compressor, etc. are dealt with by operating at a low speed rotation advantageous for the compressor. .

  Moreover, the block diagram of the air conditioner by other Embodiment of this invention is shown in FIG. 1 is a compressor, 2 is an electric motor, 3 is an outdoor heat exchanger, 4 is an electronically controlled expansion valve, and 5 is an indoor heat exchanger. 6 is a frequency variable device, and 7 is a control device. The control device 7 includes a storage function, a calculation function, a control unit 71 that controls these functions, and a valve drive unit that operates the electronically controlled expansion valve 4 based on an output signal (valve opening command signal) of the control unit 71. 72.

  In the air conditioner using the refrigerant circuit configuration according to another embodiment of the present invention as described above, the refrigerant flow rate control is performed by the compressor 2 and the electronically controlled expansion valve 4, so that the electronically controlled expansion is performed. If the valve fails, the refrigerant flow rate cannot be controlled. However, it is necessary to confirm that the expansion valve is actually driven because the failure of the electronically controlled expansion valve cannot be accurately diagnosed only by the operating state during service. Therefore, when the electronically controlled expansion valve is driven by being energized in the open direction, the open direction energization is performed as a failure diagnosis mode at the time of service by utilizing the clicking sound when fully opened. Make a decision. If there is a sound, the electronically controlled expansion is normal because it is driving, and if there is no sound, it is a failure.

  Next, an example of a mechanism that makes a sound when the electronically controlled expansion valve is fully opened will be described with reference to FIG. FIG. 12 is a cross-sectional view of an example of an electronically controlled expansion valve. The driving principle will be briefly explained. The portion shown in the figure is a stepping motor, and the rotor 11 rotates. The rotating operation is converted into a vertical motion by a screw, and the valve 12 is provided with an opening / closing motion. Yes. Then, when the valve advances in the opening direction, the protrusion A13 attached to the rotor comes into contact with the protrusion B14 to make a sound.

  As described above, in another embodiment of the present invention, energization in the opening direction is performed at the time of service, and the sound generated when the electronically controlled expansion valve is fully opened can be confirmed, so that a reliable failure diagnosis can be performed. .

It is a block diagram which shows the air conditioner by Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the frequency and capability of the air conditioner by Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the frequency of the air conditioner by Embodiment 1 of this invention, and a setting optimal valve-opening value. It is explanatory drawing which shows the relationship between the frequency of the air conditioner by Embodiment 1 of this invention, and preset discharge temperature. It is detail drawing which shows the positional relationship of the inlet thermistor and intermediate | middle thermistor of the heat exchanger of the air conditioner by Embodiment 1 of this invention. It is a control flowchart which shows the air conditioner by Embodiment 1 of this invention. It is a flowchart which shows the detail of the block 714 of FIG. 6 of the air conditioner by Embodiment 1 of this invention. It is a block diagram which shows the air conditioner by other Embodiment of this invention. It is a control flowchart which shows the air conditioner by other Embodiment of this invention. It is a flowchart which shows the detail of the control block which shows the air conditioner by other Embodiment of this invention. It is a block diagram which shows the air conditioner by other Embodiment of this invention. It is sectional drawing of the electronically controlled expansion valve which shows the air conditioner by other Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Electric motor, 3 Outdoor heat exchanger, 4 Electronically controlled expansion valve, 5 Indoor heat exchanger, 6 Frequency variable device, 7 Control device, 8 Discharge temperature detection thermistor, 9 Inlet temperature detection thermistor, 10 Intermediate temperature detection thermistor,

Claims (3)

Compressor, indoor heat exchanger, electronically controlled expansion valve, outdoor heat exchanger constitute a refrigeration cycle, and the compressor discharge temperature is abnormally reduced in an air conditioner driven by an inverter An air conditioner characterized by changing the maximum frequency. In addition to abnormally lowering the discharge temperature of the compressor, if the compressor frequency is above a certain value and the valve opening drive signal to the electronically controlled expansion valve is below a certain value, change the maximum frequency of the compressor. The air conditioner according to claim 1, wherein Compressor, indoor heat exchanger, electronically controlled expansion valve, outdoor heat exchanger constitute the refrigeration cycle, and the compressor is inverter-driven air conditioner. As an air conditioner, the electronically controlled expansion valve is energized in the opening direction.

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