JP6202274B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner having a dilution sensor that measures the dilution of refrigerant oil by refrigerant.

  Patent Document 1 discloses an air conditioner in which a dilution sensor is provided in a compressor and, for example, an electronic expansion valve included in a refrigeration cycle is controlled based on the dilution measured by the dilution sensor. Have been described. Here, the dilution refers to the dilution of the refrigeration oil with the refrigerant, and refers to the ratio of the refrigerant dissolved in the refrigeration oil, (mass of refrigerant dissolved in the refrigeration oil) / (mass of refrigerant dissolved in the refrigeration oil + Defined as the mass of refrigeration oil).

  The dilution sensor utilizes the fact that the relative permittivity of the refrigerating machine oil and the refrigerant are different, and has at least a pair of electrode plates arranged opposite to each other with a dielectric interposed therebetween, and the capacitance value between the electrode plates By measuring the relative dielectric constant, the dilution is calculated.

  Since the dilution sensor is disposed in the refrigerator oil reservoir of the compressor and used under severe conditions such as vibration, the distance between the electrode plates may change when used for a long period of time. is there.

  When the distance between the electrode plates changes, the measured capacitance value also changes, so an error occurs between the actual dilution and the dilution measured by the dilution sensor, and the air conditioning is not accurate. There is a problem that operation control of the machine is performed.

JP-A-5-5562

  Accordingly, an object of the present invention is to enable evaluation of the reliability (measurement accuracy) of a dilution sensor that is actually used during operation of the air conditioner in an air conditioner having a dilution sensor. There is.

In order to solve the above problems, the present invention provides a refrigerant circuit including a compressor, a condenser, an expansion valve, and an evaporator, a refrigerator oil temperature sensor for measuring the refrigerator oil temperature in the compressor, and the dilution of the refrigerator oil by the refrigerant. Air having a dilution sensor for measuring the concentration and a condensing temperature sensor for measuring the condensing temperature of the condenser, and a control means for controlling the operation of the refrigerant circuit based on the output from the measuring means In the harmony machine,
The control means compares the condensing temperature or the condensing pressure converted from the condensing temperature with the estimated dilution corresponding to the refrigerating machine oil temperature and the actual measured dilution measured by the dilution sensor, and With the function to evaluate the reliability of the dilution sensor ,
The estimated dilution is such that the compressor temperature determined by the refrigerator oil temperature or the refrigerant temperature in the compressor is T1, the condensation temperature is T2, and the temperature difference ΔT (= T1−T2) is positive. The degree of dilution in which the changes in the condensation pressure and the refrigeration oil temperature within a predetermined time are within a certain range, and the dilution corresponding to the condensation pressure and the refrigeration oil temperature in a steady operation state of the refrigerant circuit is tabulated. It is characterized by being obtained from a data table .

  The control means is configured such that the refrigerator oil temperature is higher than the maximum condensation temperature value in the operation range of the refrigerant circuit, and each change in the condensation pressure and the refrigerator oil temperature within a predetermined time is within a certain range. The estimated dilution is obtained from the dilution data table in the steady operation state of the stored refrigerant circuit.

  Further, the control means sets a predetermined threshold value including an upper limit value and a lower limit value for the estimated dilution factor, and when the actual measurement dilution factor deviates from the threshold value, the dilution sensor is displayed on a predetermined display unit. The abnormality is displayed, and the operation of the refrigerant circuit is controlled by excluding the dilution measured by the dilution sensor, or the operation of the refrigerant circuit is stopped.

  According to the present invention, when the air conditioner is operated using the dilution by the dilution sensor as one of the control factors, the condensation temperature of the condenser or the estimation obtained from the condensation pressure converted from the condensation temperature and the refrigerator oil temperature is estimated. By comparing the dilution and the actual measurement dilution measured by the dilution sensor to evaluate the reliability (measurement accuracy) of the dilution sensor, the dilution sensor has become abnormal. It is possible to prevent erroneous control operation of the air conditioner at the time.

The schematic diagram which shows the structure of the air conditioner which concerns on embodiment of this invention. Sectional drawing which shows an example of a dilution sensor. The figure which shows an example of the dilution data table used by this invention.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited to this.

  Referring to FIG. 1, an air conditioner 1 according to this embodiment includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an electronic expansion valve 14, and an indoor heat exchanger 15 as basic components. A refrigerant circuit 10 that is sequentially connected through a pipe and a control unit 20 that includes a microcomputer that controls the refrigerant circuit 10 are provided.

  In the refrigerant circuit 10, during the cooling operation, the four-way valve 12 is switched as shown by a solid line in FIG. The condenser 13 functions as a condenser, the indoor heat exchanger 15 functions as an evaporator, and the low-pressure refrigerant heat-exchanged with the indoor air in the indoor heat exchanger 15 is returned to the compressor 11 via the accumulator 16. .

  At the time of heating operation, the four-way valve 12 is switched as shown by a chain line in the figure, the high-pressure gas refrigerant adiabatically compressed by the compressor 11 is flowed toward the indoor heat exchanger 15, and the indoor heat exchanger 13 serves as a condenser The outdoor heat exchanger 15 functions as an evaporator, and the low-pressure refrigerant heat-exchanged with the outdoor air in the outdoor heat exchanger 15 is returned to the compressor 11 via the accumulator 16.

  As described above, the refrigerant circuit 10 operates as a reversible cycle by switching the four-way valve 12. However, in the following description, the outdoor heat exchanger 13 is referred to as a condenser 13A in the case of the cooling operation. is there.

  In this embodiment, the compressor 11 is a rotary compressor, and a refrigerant compression unit 111 in which a rotary piston (both not shown) is housed in a sealed container 110 in a cylinder, and an electric motor 112 that drives the rotary piston, Is stored. A predetermined amount of refrigerating machine oil is stored in the sealed container 110, and the bottom side thereof is a refrigerating machine oil storage part 11b. The compressor 11 may be a scroll compressor.

  In addition, the air conditioner 1 according to this embodiment includes at least a refrigerating machine oil temperature sensor 31, a dilution sensor 32, and a condensation temperature sensor 33 as measurement means. Measurement signals (measurement values) of these sensors 31, 32, and 33 are transmitted to the control means 20 via an A / D converter (not shown).

  Both the refrigerating machine oil temperature sensor 31 and the dilution degree sensor 32 are arranged so as to be immersed in the refrigerating machine oil in the refrigerating machine oil reservoir 10b. The condensing temperature sensor 33 measures the refrigerant temperature when the refrigerant condenses in the condenser 13A. The condensing temperature sensor 33 is preferably disposed in an intermediate portion of a path (refrigerant piping) passed through the condenser 13A. The intermediate temperature of the condenser 13A is measured as the condensation temperature.

  A thermistor, a thermocouple element, or the like may be used for the refrigerator oil temperature sensor 31 and the condensation temperature sensor 33.

  As illustrated in FIG. 2, the dilution sensor 32 includes a comb-shaped first electrode plate 321 and a comb-shaped second electrode plate 322 such that a predetermined space 324 is generated therebetween. Capacitors in which the dielectrics 323 are alternately combined as spacers are used, and the relative permittivity of the refrigerating machine oil entering the space 324 is measured.

  The degree of dilution (the degree of dilution of the refrigerating machine oil due to the refrigerant) is calculated from the relative permittivity of the refrigerating machine oil. The calculation function may be provided in the dilution sensor 32, or the control means 20 may control The dilution degree may be calculated from the relative dielectric constant.

  Based on the measurement signals (measured values) from the sensors 31, 32, 33, the control means 20 controls the rotational speed of the motor 112 of the compressor 11 in the refrigerant circuit 10, the opening degree of the electronic expansion valve 14, and the like. Although controlled, the present invention has a function of evaluating the reliability (accuracy of the measurement value) of the dilution sensor 32.

  The dilution level measurement by the dilution level sensor 32 requires a transient operating state immediately after the start of the compressor 11 or during a defrosting operation, a temperature difference between the compressor temperature T1 and the condensation temperature T2. ΔT (= T1−T2) is on the negative side (ΔT <0), and is limited to an abnormal operation state in which the refrigerant is condensed (liquefied) in the compressor 11.

  The compressor temperature T1 may be a refrigeration oil temperature measured by the refrigeration oil temperature sensor 31, or a refrigerant discharge temperature attached to the refrigerant discharge pipe 11a of the compressor 11 as shown in FIG. The refrigerant discharge temperature measured by the sensor 35 may be used. The condensation temperature T2 is preferably an intermediate temperature of the condenser 13A as described above.

  If the operation of the refrigerant circuit 10 is stable with respect to the above transient operation state or abnormal operation state, dilution is performed from the condensation pressure converted from the condensation temperature T2 and the refrigerator oil temperature. The degree can be estimated.

  Therefore, ΔT (= T1−T2) is on the plus side (ΔT> 0), and the condensation pressure and the refrigeration oil temperature when the refrigerant circuit 10 is in the steady operation state are measured, and the respective measured values are obtained. Create a dilution data table in which the corresponding dilutions are tabulated in advance, obtain the estimated dilution during steady operation from this dilution data table, and use the dilution sensor for actual measurement and estimated dilution during steady operation. To determine whether there is an error.

  However, the actual measured dilution and the estimated dilution are compared when the following first and second conditions are satisfied.

  First condition: Suppose that the compressor temperature is higher (eg, 70 ° C. or higher) than the maximum condensation temperature (eg, 65 ° C.) in the operating range. Thereby, ΔT is always kept at 5 ° C. or higher.

  Second condition: It is assumed that each change in the condensation pressure and the refrigerator oil temperature within a certain time is within a predetermined range. As an example, the condensation pressure and the refrigerator oil temperature are measured 10 times every minute, and the case where each value is within ± 3 ° C. is determined as the steady operation state.

  Since the condensation pressure and the condensation temperature are in a one-to-one correspondence relationship, the condensation temperature may be used instead of the condensation pressure. Further, the temperature of the refrigerating machine oil is measured not by the refrigerating machine oil sensor 31 but by attaching a temperature sensor 34 to the outer wall of the refrigerating machine oil storage part 11b outside the sealed container 110 as shown in FIG. The surface temperature of the compressor 11 may be substituted.

  Here, FIG. 3 shows a part of the dilution data table created corresponding to the condensation pressure (condensation temperature) measured in the refrigerant circuit using the R410A refrigerant and the POE (polyol ester) refrigerating machine oil and the refrigerating machine oil temperature. Show.

  When the upper limit of the condensing temperature in the refrigerant use range is 65 ° C., when the refrigerator oil temperature reaches 70 ° C., which is higher than that, the actual measured dilution by the dilution sensor 32 is compared with the estimated dilution. However, the condensation temperature and the refrigerator oil temperature are measured every minute, and when the fluctuation for 10 minutes is within ± 3 ° C., it is determined that it is in a steady operation state.

  Then, from the condensation temperature and the refrigerator oil temperature in the steady operation state, the estimated dilution degree is obtained from the dilution degree data table of FIG.

  For example, the estimated dilution when the condensation temperature is 50 ° C. and the refrigerator oil temperature is 70 ° C. is 22.6 wt%. If the condensation temperature and the refrigerator oil temperature are allowed to vary by ± 3 ° C., the lowest dilution within this range is 19.4 wt% of the condensation temperature 47 ° C. and the refrigerator oil temperature 73 ° C. Further, the highest dilution within this range is 26.4 wt% at a condensation temperature of 53 ° C. and a refrigerator oil temperature of 67 ° C.

  Therefore, the dilution may vary by 7.0 wt% (19.4 wt% to 26.4 wt%). This is the normal range of dilution. If the actual measured dilution measured by the dilution sensor 32 is within the normal range, the dilution sensor 32 maintains the expected performance and determines that the sensor is normal.

  For example, 22.6 ± 5 wt% (17.6 wt% to 27.6 wt%) in consideration of errors in the refrigerator oil temperature sensor 31, the dilution sensor 32, the condensation temperature sensor 33, and the dilution data table. %) Is the caution range.

  As an example of the determination method when the actual measured dilution by the dilution sensor 32 deviates from the normal range and becomes the caution range, the first case determines that the sensor is normal. If there is, it is determined as “sensor abnormality”. If the actual measurement dilution is out of the caution range from the first time, it is determined that the sensor is abnormal at that time.

  When it is determined that the sensor is abnormal, the control unit 20 displays the determination result on the display unit 21 including, for example, an LCD or an LED, and excludes the degree of dilution measured by the degree of dilution sensor 32, and the refrigerant circuit. 10 is controlled, or the operation of the refrigerant circuit 10 is stopped. Thereby, the user can know that there is an abnormality in the dilution sensor, and can prevent an erroneous control operation of the air conditioner due to the abnormality (defective) of the dilution sensor.

DESCRIPTION OF SYMBOLS 1 Air conditioner 10 Refrigerant circuit 10b Refrigerating machine oil storage part 11 Compressor 111 Refrigerant compression part 112 Electric motor 12 Four-way valve 13 Outdoor heat exchanger 13A Condenser at the time of cooling operation 14 Electronic expansion valve 15 Indoor heat exchanger 16 Accumulator 20 Control means 21 Display Unit 31 Refrigerating Machine Oil Temperature Sensor 32 Dilution Sensor 321 First Electrode Plate 322 Second Electrode Plate 323 Dielectric (Spacer)
33 Condensation temperature sensor

Claims (3)

A refrigerant circuit including a compressor, a condenser, an expansion valve and an evaporator, a refrigerator oil temperature sensor for measuring the temperature of the refrigerator oil in the compressor, a dilution sensor for measuring the dilution of the refrigerator oil by the refrigerant, and the condenser In an air conditioner comprising a measuring means including a condensing temperature sensor for measuring a condensing temperature, and a control means for controlling the operation of the refrigerant circuit based on an output from the measuring means,
The control means compares the condensing temperature or the condensing pressure converted from the condensing temperature with the estimated dilution corresponding to the refrigerating machine oil temperature and the actual measured dilution measured by the dilution sensor, and With the function to evaluate the reliability of the dilution sensor ,
The estimated dilution is such that the compressor temperature determined by the refrigerator oil temperature or the refrigerant temperature in the compressor is T1, the condensation temperature is T2, and the temperature difference ΔT (= T1−T2) is positive. The degree of dilution in which the changes in the condensation pressure and the refrigeration oil temperature within a predetermined time are within a certain range, and the dilution corresponding to the condensation pressure and the refrigeration oil temperature in a steady operation state of the refrigerant circuit is tabulated. An air conditioner characterized by being obtained from a data table . The control means is such that the refrigerator oil temperature is higher than the maximum condensation temperature value in the operation range of the refrigeration cycle, and the changes in the condensation pressure and the refrigerator oil temperature within a predetermined time are within a certain range. 2. The air conditioner according to claim 1 , wherein the estimated dilution is obtained from the dilution data table when the refrigerant circuit is in a steady operation state. The control means sets a predetermined threshold value including an upper limit value and a lower limit value for the estimated dilution factor. When the actual measurement dilution factor deviates from the threshold value, the dilution factor sensor is abnormal on a predetermined display unit. and it displays that the claim 1, characterized in that by excluding the dilution was measured by the dilution sensor operatively controlling the operation of the refrigerant circuit, or to stop the operation itself of the refrigerant circuit Or the air conditioner of 2 .

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