JP6087269B2 - Corrosion diagnosis method for air conditioner and heat exchanger for air conditioner - Google Patents

Description

The present invention relates to an air conditioner including a heat exchanger using an aluminum tube and a corrosion diagnosis method for the heat exchanger for an air conditioner, and more particularly to a room having a heat exchanger using an aluminum flat tube. It is suitable for air conditioners such as air conditioners and packaged air conditioners.
In this specification and claims, the term “aluminum” is used to include aluminum and its alloys.

  Currently, cross fin tube heat exchangers are frequently used as heat exchangers used in air conditioners. This cross fin tube type heat exchanger has a hole with a restriction at a predetermined position of a strip-shaped aluminum fin, and after inserting a copper-made circular heat transfer tube (pipe-shaped heat transfer tube), It is manufactured by mechanically expanding the heat transfer tube.

  On the other hand, instead of the conventional copper heat transfer tubes, aluminum flat tubes are used instead of the conventional copper heat transfer tubes, and the flat tubes, fins, and headers are brazed to reduce costs, price stability, size, and weight. Parallel flow heat exchangers that are manufactured in this way have been developed. In particular, in an air conditioner for an automobile, an aluminum heat exchanger that can be reduced in size and weight has been adopted in order to improve fuel efficiency and expand a living space.

  In general, an alumite layer of an oxide film is naturally formed on the surface of aluminum, thereby ensuring corrosion resistance. However, if there is a substance that breaks the oxide film, such as chloride ions, pitting corrosion that proceeds locally in the thickness direction of the flat tube constituting the heat exchanger may occur. When pitting corrosion progresses in the flat tube, there is a possibility that a through hole is made in the flat tube and the internal high-pressure refrigerant leaks. In the cross fin tube type heat exchanger described above, corrosion of the copper heat transfer tube is suppressed by corrosion of the aluminum fin. However, in the parallel flow type heat exchanger described above, both the fin and the flat tube are made of aluminum. Heat transfer tubes are more easily corroded than tube heat exchangers.

  The air conditioner may be used in an area near the coast where there is a lot of salt or in a high temperature and high humidity area. In this case, in particular, the heat exchanger for the outdoor unit constituting the air conditioner is installed in a place with severe outdoor conditions from the viewpoint of corrosion, such as a place where there is a lot of salt or high temperature and humidity in the atmosphere. .

  Further, in air conditioners, a chlorofluorocarbon refrigerant is generally used. For example, Freon R410A is widely used in room air conditioners, but its global warming potential (GWP) is relatively high at about 2000. R32, which is being adopted in recent years, has a global warming potential of about 1/3 compared to R410A. However, R410A is nonflammable, while R32 classifies the refrigerant combustion category as slightly flammable. For this reason, the refrigerant leakage due to the malfunction of the heat exchanger affects not only malfunction of the air conditioner but also other factors such as environmental problems.

  Therefore, when the air conditioner heat exchanger is made of aluminum, in order to prevent refrigerant leakage, high corrosion resistance (corrosion resistance), especially pitting corrosion, should be prevented during the set service life of the air conditioner. Is required.

  On the other hand, it is proposed to provide a detector for detecting refrigerant leakage as described in JP-A-8-327195 (Patent Document 1) assuming that the refrigerant leaks due to corrosion or the like. . Thus, by providing a detector (refrigerant leak sensor) that detects refrigerant leakage, it is possible to directly detect refrigerant leakage even when the air conditioner is in operation or stopped. However, in the thing of this patent document 1, a dedicated refrigerant leak measuring apparatus is needed and will become expensive.

JP-A-8-327195

  Air conditioners are installed in places with severe outdoor conditions from the viewpoint of corrosion, such as places with a lot of salt or high temperature and high humidity, so that corrosive substances such as salt adhere to the piping material and heat exchange for air conditioners. When the corrosion of the vessel is significantly accelerated, it determines the life of the heat exchanger and shortens the life of the heat exchanger. In particular, when an air conditioner installed in a highly corrosive environment such as a beach area is exposed to severe weather conditions locally, the life of the heat exchanger tends to be shortened.

  As a refrigerant leak diagnosis due to corrosion in a heat exchanger for an air conditioner installed in such a harsh environment, there is one using a refrigerant leak sensor as in Patent Document 1, but as described above, A dedicated refrigerant leak measuring device is required, and there is a problem that it becomes expensive.

In general, air conditioners are designed and manufactured to withstand corrosion during their useful life, and it is thought that the frequency of pitting corrosion due to corrosion caused by severe weather conditions is low. . It is a problem to reduce the price of a corrosion diagnosis apparatus such as a refrigerant leak measurement apparatus for an event with a low occurrence frequency.
Moreover, the thing using the refrigerant | coolant leak sensor as described in the said patent document 1 has the subject that a refrigerant | coolant leak sensor cannot maintain the stable detection performance over a long term with the contaminant in an environment, Furthermore, patent document 1 However, there is a problem that the refrigerant cannot be prevented from leaking.

  An object of the present invention is to provide an air conditioner and an air conditioner that can detect corrosion in advance leading to refrigerant leakage in a heat exchanger in advance, enable stable corrosion detection over a long period of time, and realize corrosion diagnosis at low cost. The object is to obtain a corrosion diagnosis method for heat exchangers.

  In order to achieve the above object, the present invention provides an air conditioner including an outdoor unit having a heat exchanger, the first temperature sensor for measuring the temperature of an arbitrary portion of the outdoor unit, and the first temperature sensor. A second temperature sensor for detecting the temperature of the same portion; and an external exposed electrode that has an exposed electrode that is exposed to the outside and is connected in parallel to the second temperature sensor. The salinity adhesion amount to the heat exchanger is estimated based on a difference between an output value and an output value from the second temperature sensor.

  Another feature of the present invention is an air conditioner including an outdoor unit having a heat exchanger, which is substantially the same as the first temperature sensor that measures the temperature of an arbitrary location of the outdoor unit. A second temperature sensor that detects the temperature of the location, and an external exposed electrode that has an exposed electrode that is exposed to the outside air and that is connected in parallel to the second temperature sensor, from the first temperature sensor The relative humidity at which salinity begins to deliquesce is defined as the time point when the difference between the output value from the second temperature sensor and the output value from the second temperature sensor begins to increase. The change in relative humidity is calculated from the change in temperature, and based on the difference between this relative humidity and the output value of the first temperature sensor and the second temperature sensor in the environment of the relative humidity, the salt content adheres to the heat exchanger. To estimate the quantity In corrosion diagnostic method of an air conditioner heat exchanger for the symptoms.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to detect the corrosion which leads to the refrigerant | coolant leakage of a heat exchanger in advance, the stable corrosion detection is enabled over a long period, and also it can implement | achieve a corrosion diagnosis at low cost, and an air conditioner There is an effect that a corrosion diagnosis method for a heat exchanger can be obtained.

It is a figure explaining Example 1 of the air conditioner of this invention, and is a schematic perspective view of the outdoor unit which comprises an air conditioner. It is a figure explaining the fin shape used for the heat exchanger shown in FIG. 1, and the front view (a) and side view (b) of a heat exchanger at the time of employ | adopting a strip-shaped straight fin. It is a figure explaining the other fin shape used for the heat exchanger shown in FIG. 1, and the front view (a) and side view (b) of a heat exchanger at the time of employ | adopting a corrugated fin. FIG. 3 is a structural diagram showing an example of an externally exposed electrode connected in parallel to the second temperature sensor shown in FIG. 1. FIG. 6 is a structural diagram showing another example of externally exposed electrodes connected in parallel to the second temperature sensor shown in FIG. 1. FIG. 6 is a structural diagram showing still another example of an externally exposed electrode connected in parallel to the second temperature sensor shown in FIG. 1, wherein (a) is a plan view and (b) is a side view. BRIEF DESCRIPTION OF THE DRAWINGS The block diagram explaining the corrosion diagnostic apparatus of the heat exchanger in Example 1 of this invention. The diagram which shows an example of the output result of the synthetic | combination resistance value detected with the 2nd temperature sensor shown in FIG. The diagram explaining detecting the time of relative humidity becoming 75% from the change of temperature difference (DELTA) T of the measurement temperature of a 1st temperature sensor and a 2nd temperature sensor. The diagram which shows the relationship between the temperature in air | atmosphere environment, relative humidity, and absolute humidity. The diagram for estimating the amount of salt adhesion from temperature difference (DELTA) T of a 1st temperature sensor and a 2nd temperature sensor, and relative humidity RH. Explanatory drawing which diagnoses a corrosion level from the estimated salt adhesion amount and wetting time. It is a figure explaining Example 2 of the air conditioner of this invention, and is a schematic perspective view of the outdoor unit which comprises an air conditioner. FIG. 14 is a structural diagram showing the first temperature sensor shown in FIG. 13. FIG. 14 is a structural diagram showing a second temperature sensor shown in FIG. 13. FIG. 14 is a structural diagram illustrating an example of an integrated sensor configured by integrating the first temperature sensor and the second temperature sensor shown in FIG. 13.

  Specific embodiments of the corrosion diagnosis method for an air conditioner and a heat exchanger for an air conditioner according to the present invention will be described below with reference to the drawings. Note that, in each drawing, the portions denoted by the same reference numerals indicate the same or corresponding portions.

  A first embodiment of the present invention will be described with reference to FIGS. First, the structure of the air conditioner of the first embodiment will be described with reference to FIGS.

  FIG. 1 is a schematic perspective view of an outdoor unit constituting the air conditioner of the first embodiment.

  In FIG. 1, a heat exchanger 30 and a compressor 50 that constitute a refrigeration cycle are installed inside an outdoor unit 40. A blower fan for ventilating the heat exchanger 30 is installed inside the outdoor unit 40, and the blower fan 60 is an axial fan (propeller fan).

  The heat exchanger 30 is provided between a pair of left and right refrigerant headers 31 and 32 that are installed in parallel and vertically, and between the refrigerant headers 31 and 32, and communicates the refrigerant headers 31 and 32. It is comprised by the some flat tube 33 etc. which were connected so that it might make. The refrigerant headers 31 and 32 and the flat tube 33 are all made of aluminum.

  The plurality of flat tubes 33 are stacked in the vertical direction (gravity direction), and the flat tubes 33 are arranged in the horizontal direction. A large number of aluminum fins 34 are provided at predetermined intervals (gap) between the flat tubes 33 adjacent in the vertical direction. The refrigerant headers 31, 32, the flat tubes 33, and the fins 34 are put into a furnace in a state of being assembled together, and are brazed and integrated. In addition, the refrigeration cycle which comprises the air conditioner of a present Example uses slightly flammable R32 with a low global warming potential (GWP) as a refrigerant | coolant. However, the present invention is not limited to R32 with respect to the refrigerant.

  The configuration of the fins 34 used in the heat exchanger 30 will be described with reference to FIG. FIG. 2 is a view for explaining the fin shape used in the heat exchanger shown in FIG. 1, and is a front view (a) and a side view (b) of the heat exchanger when strip-shaped straight fins are employed.

  As shown in FIG. 2, in this embodiment, the fins 34 used in the heat exchanger 30 are constituted by strip-shaped straight fins. The fins 34 are formed of aluminum strip-like straight fins, and are inserted into the fins 34 so as to sandwich the flat tube 33 in a rectangular plate-shaped material as shown in FIG. The slit portion 34a and an uneven portion 34b formed between the slit portions 34a for improving the heat exchange performance are provided. The fins 34 are arranged in parallel so that a large number of the fins 34 are stacked at a predetermined interval, and the plurality of flat tubes 33 are inserted into the slit portions 34 a of the numerous fins 34.

  In this embodiment, the fin 34 is described as an example of a strip-shaped straight fin. However, the fin 34 is not limited to the strip-shaped straight fin, and a corrugated fin 35 as shown in FIG. It may be configured.

  That is, FIG. 3 is a diagram for explaining another fin shape used in the heat exchanger 1 shown in FIG. 1, and a front view (a) and a side view (b) of the heat exchanger when corrugated fins are employed. ). In the example shown in FIG. 3, a fin 35 obtained by bending a thin aluminum plate into a corrugated shape (corrugated shape) is inserted between the flat tubes 33 and brazed. Further, the corrugated fins 35 are formed with fine slits 35a as shown in FIG. 5 (b) to improve the heat exchange performance.

  As described above, in this embodiment, the fins constituting the heat exchanger 30 can be of various fin shapes such as strip-shaped straight fins shown in FIG. 2 and corrugated fins shown in FIG. is there. 2 and 3, the refrigerant headers 31 and 32 shown in FIG. 1 are omitted.

  When the heat exchanger 30 shown in FIG. 1 acts as a condenser in a refrigeration cycle (not shown), gaseous refrigerant flows into the refrigerant header 31 from the refrigerant gas piping of the refrigeration cycle. In the flat tube 33, the heat is exchanged with the air in order to condense, finally liquefy and flow out to the refrigerant liquid piping of the refrigeration cycle connected to the refrigerant header 32.

When the heat exchanger 30 is operated as an evaporator, conversely, the gas-liquid two-phase refrigerant having a low degree of freshness after passing through the expansion valve flows from the refrigerant liquid pipe into the refrigerant header 32 and sequentially evaporates in the flat pipe 33. The gaseous refrigerant then flows out from the refrigerant header 31 to the refrigerant gas pipe.
Air can be circulated between the fins 34, and heat can be exchanged between the air and the refrigerant by flowing the refrigerant from the refrigerant header 31 or 32 into the flow path in the flat tube 33.

  A sacrificial anode layer is provided on the surface of each flat tube 33. The sacrificial anode layer is formed of a metal having a lower potential than the aluminum core material forming the refrigerant flow path (space) portion, so that the sacrificial anticorrosive effect can be obtained. In other words, the flat aluminum tube 33 is normally manufactured by extrusion molding. However, zinc spraying is performed on the surface of the flat aluminum tube after the extrusion molding, and is diffused by the heat at the time of brazing as described above. A diffusion layer is formed. Alternatively, the flat tube 33 may be formed of an aluminum clad layer retrofitted with another aluminum layer.

  In the present embodiment, a corrosion diagnosis device is provided in order to estimate the amount of salt (chloride ions) adhering to the heat exchanger 30 which is the main cause of corrosion of the aluminum heat exchanger. That is, as shown in FIG. 1, in the outdoor unit 40, there are a first temperature sensor 10 and a second temperature sensor 20 installed at a portion where the ambient temperature is the same as that of the first temperature sensor 10. Is provided. The second temperature sensor 20 includes an externally exposed electrode 21 that is connected in parallel to the second temperature sensor 20 and is exposed to the outside air. The externally exposed electrode 21 is attached to the same temperature environment as the first temperature sensor 10 and the second temperature sensor 20 through a heat exchanger.

  In the present embodiment, as shown in FIG. 1, the externally exposed electrode 21 is provided in the lower portion near the center of the heat exchanger 30 where corrosion is most likely to proceed. For example, as shown in FIGS. 2 and 3, the heat exchanger 30 may be installed in a space surrounded by a flat tube 33 and fins 34 or 35 near the center of the heat exchanger 30.

  The externally exposed electrode 21 has a structure in which resistance is large and current does not flow when no salt is attached to the exposed electrode, and the resistance decreases when salt is attached to the exposed electrode and the salt is deliquescent. Current flow. The second temperature sensor 20 normally exhibits the same output value (temperature measurement value) as the first temperature sensor, but when a current flows through the externally exposed electrode 21, the output value (temperature measurement) of the second temperature sensor 20 is detected. Value) is changed. That is, the temperature sensor detects the temperature by detecting a resistance value that changes according to the temperature. However, since the external exposure electrode 21 is connected in parallel to the second temperature sensor 20, the external exposure is performed. When a current flows through the electrode 21 and its resistance value decreases, the combined resistance value detected by the second temperature sensor 20 becomes smaller than the resistance value detected by the first temperature sensor 10. Accordingly, the temperature between the temperature measurement value detected by the first temperature sensor 10 (ambient environment temperature) and the temperature measurement value detected by the second temperature sensor 20 (showing a value smaller than the ambient environment temperature). A difference (difference in output value) ΔT occurs.

  That is, as the amount of salt attached to the externally exposed electrode 21 increases, the resistance value at the externally exposed electrode 21 decreases, so that the temperature difference ΔT increases. The present embodiment utilizes this principle and measures the amount of adhered salt from the temperature difference ΔT between the first temperature sensor and the second temperature sensor.

The outputs of the first temperature sensor 10 and the second temperature sensor 20 are transmitted to the outdoor side controller 70 in the same manner as the outputs of the other temperature sensors. Based on the temperature measurement values (resistance values) from the first temperature sensor 10 and the second temperature sensor 20 taken into the outdoor control unit 70, the outdoor control unit 70 obtains a temperature difference ΔT and The amount of salt attached to the exposed electrode 21, that is, the amount of salt attached to the heat exchanger 30 of the outdoor unit 40 can be estimated.
The first temperature sensor 10 and the second temperature sensor 20 may be a can-sealed thermistor sensor that is usually used for temperature detection of an air conditioner.

As a result of a field monitor test in which an outdoor unit 40 was installed on a house veranda for several years in Okinawa, where salt damage is relatively high in Japan and is considered to be hot and humid, pitting corrosion progresses due to adhesion of many chloride ions. The portion that is easy to do is the lower position in the vertical direction of the heat exchanger 30, and a large amount of chloride ions easily adhere to the vicinity of the vertical center and the horizontal center where the wind speed of the heat exchanger 30 increases. It was found that this is a portion where pitting corrosion tends to proceed.
Therefore, as described above, the externally exposed electrode 21 is located at a lower position in the vertical direction of the heat exchanger 30 where corrosion is most likely to proceed, or in the vicinity of the vertical center or the horizontal center where the wind speed of the heat exchanger 30 increases. It is preferable to install in the vicinity.

Next, an example of the structure of the externally exposed electrode 21 connected in parallel with the second temperature sensor 20 will be described with reference to FIGS.
FIG. 4 is a structural diagram showing an example of the externally exposed electrode 21 connected in parallel to the second temperature sensor 20 shown in FIG. As shown in FIG. 4, the externally exposed electrode 21 has an exposed electrode 23 formed on an insulating substrate 22 and is connected to a lead wire 26 by a connection pad 24 at the end of the exposed electrode 23. Further, the connecting portion between the lead wire 26 and the connection pad 24 is covered with a coating agent 25 so that only the exposed electrode 23 is exposed. As a result, when salinity adheres to the exposed electrode 23 and the salinity is deliquescent, the electrical resistance is reduced and current flows. In addition, a material having a smaller electrical resistance is used as the amount of adhering salt is larger.

FIG. 5 is a structural diagram showing another example of the externally exposed electrode 21 connected in parallel to the second temperature sensor 20 shown in FIG. In this example, an organic insulating thin film is used as the insulating substrate 22, so that the externally exposed electrode 21 can be deformed into a curved shape as shown in FIG. It is. The insulating substrate 22 is not limited to the organic insulating thin film, but may be any material or structure that can be bent.
The configuration in which the externally exposed electrode 21 can be curved is particularly effective when the corrugated fin 35 is employed as the fin constituting the heat exchanger 30. That is, since the corrugated fin 35 is formed in a curved shape, when the externally exposed electrode 21 is attached between the corrugated fins, the externally exposed electrode 21 can be deformed if the externally exposed electrode 21 can be bent or deformed. Can be more easily attached.
The other configurations are the same as those described with reference to FIG. 4, and the same or corresponding parts are denoted by the same reference numerals, and description thereof is omitted.

6A and 6B are structural views showing still another example of the externally exposed electrode 21 connected in parallel to the second temperature sensor 20 shown in FIG. 1, wherein FIG. 6A is a plan view and FIG. 6B is a side view.
The externally exposed electrode 21 shown in FIG. 6 is configured to seal a metal plate with an epoxy resin. The epoxy resin serves as an insulating substrate 22 ′. Reference numeral 23 'denotes an exposed electrode, and this exposed electrode 23' is molded in the same manner as a normal resin-encapsulated semiconductor. In addition, 24 'is a connection pad and 25' is a coating | covering material.

  By comprising in this way, it can be excellent in sealing performance. However, it is difficult to reduce the thickness as in the insulating substrate 22 composed of the organic insulating thin film described in FIG. However, it is possible to manufacture with a diameter of several mm, and it is possible to have a structure in which it is inserted between the strip-like straight fins 34 or between the corrugated fins 35 and fixed with an adhesive or the like.

  When the externally exposed electrode 21 cannot be inserted between the fins, a part of the fin constituting the heat exchanger is cut out, and the externally exposed electrode 21 is inserted and installed in the cut out part. May be. In addition, as the material of the exposed electrode 23 ', it is preferable to use a material that can withstand chloride ions, such as gold, platinum, titanium, and carbon.

Next, the configuration and principle of the corrosion diagnosis apparatus for the air conditioner heat exchanger according to the first embodiment will be described with reference to FIGS.
The first temperature sensor 10, the second temperature sensor 20, and the externally exposed electrode 21 described in FIG. 1 are connected to an outdoor control device 70 as shown in FIG. That is, the first temperature sensor 10 is connected to the terminals 71a and 71b of the outdoor control device 70, and the second temperature sensor 20 and the externally exposed electrode 21 are connected in parallel to the terminals 71c and 71d of the outdoor control device 70. .

  The first temperature sensor 10 and the second temperature sensor 20 use a thermistor sensor that is usually used for temperature detection of an air conditioner. The thermistor sensor detects the temperature by utilizing the change in resistance value depending on the temperature, and the first temperature sensor 10 and the second temperature sensor 20 measure the temperature of the place where they are installed.

  The first temperature sensor 10 can be used as, for example, a temperature sensor (a temperature sensor that measures the temperature on the inlet side or the outlet side of the heat exchanger) that is normally provided in the outdoor unit 40 (see FIG. 1). A thermistor sensor having a resistance value R1 that decreases as the temperature rises is used. A change in the resistance value is detected and output as a temperature value T1.

  It is indispensable that the second temperature sensor 20 is installed at the same temperature environment as the first temperature sensor 10, for example, at the same location as shown in FIG. The externally exposed electrode 21 uses the externally exposed electrode as described with reference to FIGS.

  Since the externally exposed electrode 21 is connected in parallel to the second temperature sensor 20, the resistance value R2 of the second temperature sensor 20 and the externally exposed electrode 21 decrease as the resistance value R2S of the externally exposed electrode 21 decreases. The combined resistance value R2T with the resistance value R2S decreases. That is, the resistance value on the second temperature sensor 20 side measured by the outdoor side control unit 70 decreases. The smaller the measured resistance value is, the higher the temperature value T2 output from the second temperature sensor 20 is, and thus the higher the temperature value T1 output from the first temperature sensor 10 is. . Accordingly, as the resistance value of the externally exposed electrode 21 decreases, the temperature difference ΔT between the temperature value T1 output from the first temperature sensor 10 and the temperature value T2 output from the second temperature sensor 20 increases.

  Since the externally exposed electrode 21 is exposed to the external environment, the amount of salt attached to the externally exposed electrode 21 increases by being placed in an environment with high humidity and a large amount of incoming sea salt for a long period of time. When deliquescent under high humidity, a high salinity water film 15 is formed as shown in FIG. As the salinity concentration of the water film 15 is higher, the resistance value of the externally exposed electrode 21 is decreased, and accordingly, the combined resistance value R2T on the second temperature sensor 20 side is also decreased. The output temperature value T2 shows a high value. As a result, as described above, the temperature difference ΔT between the temperature value T1 output from the first temperature sensor 10 and the temperature value T2 output from the second temperature sensor 20 increases.

The corrosion diagnostic apparatus of the present embodiment uses the above-described principle, and estimates the amount of salt attached to the heat exchanger and estimates the progress level of corrosion of the heat exchanger based on this, as will be described below. is there.
The estimation of the amount of salt adhering to the heat exchanger and the estimation of the progress level of corrosion of the heat exchanger are calculated by the outdoor control device 70 and an alarm is issued from the outdoor control device 70. it can. Alternatively, the detected values of the first and second temperature sensors 10 and 20 are transmitted via the network 73 to a remote monitoring device 72 installed at a remote management site, and the remote monitoring device 72 performs heat exchange. The remote monitoring device 72 may issue an alarm by calculating the amount of salt adhering to the vessel or estimating the progress of corrosion of the heat exchanger.

Next, the estimation of the amount of salt attached to the heat exchanger and the estimation of the progress level of corrosion of the heat exchanger will be described with reference to FIGS.
FIG. 8 is a diagram showing an example of the output result of the combined resistance value detected by the second temperature sensor 20, and the second temperature sensor 20 and external exposure when the relative humidity RH is changed according to FIG. A change in the combined resistance value R2T of the electrode 21 will be described.
The thermistor sensor used in this embodiment is an NTC thermistor (Negative Temperature Coefficient), and this thermistor has a characteristic that the resistance decreases as the temperature increases.

When NaCl (salt content) is not attached to the externally exposed electrode 21 shown in FIG. 7, the combined resistance value R2T shows a substantially constant value even when the relative humidity RH changes, as shown by a curve a. On the other hand, if NaCl is attached to the exposed electrode 23 of the external exposed electrode 21, the combined resistance value R2T decreases as shown by the curve b and the curve c. The curve b shows the case where NaCl exposed electrode 23 is adhered 1.5 mg / cm ^2, the curve c, NaCl exposed electrode 23 shows a case where adhering 15 mg / cm ^2. The environmental temperature (temperature measured by the first temperature sensor 10) is 29 ° C.

  The resistance value R1 of the first temperature sensor 10 and the resistance value R2 of the second temperature sensor 20 are configured such that the resistance values R1 and R2 do not vary even when NaCl is attached to the temperature sensor itself. For this reason, the temperature measurement values (resistance values of R1 and R2) of the first and second temperature sensors do not depend on the relative humidity RH, and are constant values as long as the environmental temperature is constant even if the relative humidity RH changes. Indicates. However, when NaCl adheres to the external exposed electrode 21 and the relative humidity RH is high, the combined resistance value R2T on the second temperature sensor 20 side also decreases due to the decrease in the resistance value R2S of the exposed electrode 23. As a result, the temperature output value (temperature measurement value) T2 on the second temperature sensor 20 side shows a high value.

  As shown in FIG. 8, even if NaCl adheres to the exposed electrode 21, if the relative humidity RH is low, the variation of the combined resistance value R2T is small. It is known that NaCl (sodium chloride), which is the main component of the flying sea salt, is liquefied at a relative humidity of approximately 75% regardless of the temperature, and a water film 15 (see FIG. 7) is rapidly formed.

  When the relative humidity is 75% or less, NaCl adhering to the exposed electrode 23 does not deliquesce and exists as salt particles, and the exposed electrode 23 is in an insulated state. For this reason, the combined resistance value R2T on the second temperature sensor 20 side is the same as the resistance value R2 of the second temperature sensor, and is output from the temperature value T1 output from the first temperature sensor 10 and the second temperature sensor 20 side. The temperature value T2 is almost the same value.

  When the relative humidity is 75% or more, NaCl is deliquesced and a water film 15 is formed between the exposed electrodes 23, so that the resistance value R2S between the exposed electrodes 23 decreases. For this reason, the combined resistance value R2T on the second temperature sensor 20 side also decreases, and as shown by the curves b and c in FIG. 8, the higher the relative humidity RH, the greater the amount of NaCl attached to the exposed electrode 23. It can be seen that the combined resistance value R2T decreases.

  Thus, the temperature difference ΔT between the temperature value T1 output from the first temperature sensor 10 and the temperature value T2 output from the second temperature sensor 20 has a correlation with the amount of salt adhesion (for example, the amount of sodium chloride attached). I know that there is.

  When estimating the salt adhesion amount based on the electric resistance R2S of the externally exposed electrode 21, the electric resistance R2S is a function R2S = f (Ws, RH) of the salt adhesion amount Ws and the relative humidity RH. For this reason, it is necessary to obtain the relative humidity even in an actual environment (an environment where an actual heat exchanger to be subjected to corrosion diagnosis is used). However, it is difficult for a humidity sensor to stably measure over a long period of time due to adsorption of environmental contaminants including salt and the like, and therefore, an air conditioner is generally not provided with a humidity sensor.

  Therefore, the present invention has been devised so that the relative humidity RH in the environment can be estimated using the output value of the externally exposed electrode 21 without using a humidity sensor. Hereinafter, this will be described with reference to FIGS. 9 and 10. FIG. 9 is a diagram for explaining that the time point when the relative humidity becomes 75% is detected from the change in the temperature difference ΔT between the measured temperatures of the first temperature sensor 10 and the second temperature sensor 20, and FIG. It is a diagram which shows the relationship between temperature, relative humidity, and absolute humidity.

  The flying sea salt is mainly composed of sodium chloride, and here, the flying sea salt is described as sodium chloride for convenience. As described above, sodium chloride is known to deliquesce at a relative humidity of approximately 75% regardless of temperature, and a water film is rapidly formed. Also in FIG. 8 described above, it is clear from the fact that the combined resistance value R2T on the second temperature sensor 20 side is abruptly lowered from the relative humidity RH of around 75%.

  Therefore, as shown in FIG. 9, the measured temperature (measured temperature becomes higher as the value of the combined resistance value R2T becomes smaller) is rapidly increased due to the relationship between the actual environmental temperature (for example, about 30 ° C.) and time. It can be considered that the relative humidity RH deliquescent of sodium chloride is 75% (= RHc). That is, as shown in FIG. 9, the relative humidity at the time when the resistance values (temperatures) of the first temperature sensor 10 and the second temperature sensor 20 show different values can be regarded as 75%. The temperature is a temperature T1 (= T1 ′) obtained from the output value of the first temperature sensor 10.

Next, the absolute humidity AH can be obtained from FIG. 10 based on the temperature T1 ′ and the relative humidity 75%. The absolute humidity AH is generally obtained by the D. Sontag equation (Z. Meteoro 1, 70, 340 (1990)). FIG. 10 shows the relationship between the temperature (° C.), the relative humidity (%), and the absolute humidity AH in the atmospheric environment calculated using this Sontag equation. Here, it can be seen from FIG. 10 that the target environment at 30 ° C. and 75% RH has an absolute humidity AH of 23 g / m ³ . In an outdoor environment, the absolute humidity is usually constant throughout the day, and the temperature and relative humidity change. That is, since the temperature is high during the daytime, the relative humidity is low, and the temperature is low at night, so the relative humidity is high. For this reason, when shifting from daytime to nighttime, the relative humidity increases and often exceeds 75%. From FIG. 9, the absolute humidity AH of the day is obtained based on FIG. 10 from the temperature (air temperature) T1 ′ at the time when the relative humidity exceeds 75% (at the time when the salinity is deliquescent) and the relative humidity (75%). be able to. Assuming the condition that the absolute humidity is constant, by measuring the time series data of the temperature, the time series data of the relative humidity can be calculated conversely from the Sontag equation or FIG.

FIG. 11 is a diagram for estimating the amount of adhering salt from the temperature difference ΔT between the first temperature sensor 10 and the second temperature sensor 20 and the relative humidity RH calculated in FIG.
As shown in FIG. 11, the salt adhesion amount Ws can be estimated from the relationship between the temperature difference ΔT between the first temperature sensor 10 and the second temperature sensor 20 and the calculated relative humidity RH.

  When the relative humidity is 75% or less, the temperature difference ΔT cannot be detected because sodium chloride is not deliquescent. When the relative humidity is 75% or more, the temperature difference ΔT changes according to the relative humidity RH and the amount of adhering salt. That is, as the relative humidity RH and the salt adhesion amount Ws increase, the temperature difference ΔT also increases.

In FIG. 11, the thick solid line is an estimated value Ws of the amount of salt attached to the heat exchanger of the outdoor unit placed in the target real environment. Dotted lines Ws1, Ws2, and Ws3 are obtained in the laboratory for the relationship between the temperature difference ΔT and the relative humidity RH by changing the amount of salt adhesion. For example, if the temperature difference ΔT at 85% RH where the temperature difference ΔT is stable is linearly interpolated, the amount of salt adhesion Ws to the heat exchanger placed in the actual environment can be estimated.
From FIG. 11, it can be seen that, for example, if the relative humidity is 85% and the temperature difference is ΔT1, the salt adhesion amount is Ws1, and if the temperature difference is ΔT2, the salt adhesion amount is Ws2.

FIG. 12 is an explanatory diagram for diagnosing the corrosion level of the heat exchanger from the estimated salt adhesion amount and the wetting time.
The atmospheric corrosion of aluminum can be arranged by the amount of salt adhesion and the wetting time (ISO9223 Standard: time satisfying temperature> 0 ° C., humidity> 80%). The higher the amount of salt and the longer the wetting time, the higher the corrosion level is, Level 1, Level 2, and Level 3. At Level 3, the corrosion progresses and there is a risk that a through hole will be formed in the heat exchanger. Indicates that it is large. In this way, the progress of corrosion in the heat exchanger, that is, the corrosion level is obtained by experiments in advance from the relationship between the amount of salt and the wetting time, and the actual use is made by preparing the diagram of FIG. The corrosion level in the inside heat exchanger can be calculated by calculating the salt adhesion amount and the wetting time. By displaying the calculated corrosion level on the outdoor control device 70, the remote monitoring device 72, or the remote control (not shown) of the air conditioner, the corrosion level can be known. When a predetermined corrosion level such as level 3 is reached, as shown in FIG. 7, if an alarm is issued from the outdoor control unit 70, the remote monitoring device 72, or the like, pitting corrosion occurs in the heat exchanger. It is possible to prevent the occurrence of the above.

  A second embodiment of the air conditioner of the present invention will be described with reference to FIGS. FIG. 13 is a schematic perspective view of an outdoor unit constituting the air conditioner of the second embodiment, FIG. 14 is a structural diagram showing the first temperature sensor shown in FIG. 13, and FIG. 15 shows the second temperature sensor shown in FIG. FIG. 16 is a structural diagram for explaining an example of an integrated sensor in which the first temperature sensor and the second temperature sensor shown in FIG. 13 are integrated. In these drawings, the parts denoted by the same reference numerals as those in the drawings for explaining the first embodiment show the same or corresponding parts. The parts different from the first embodiment will be mainly described, and the same parts will be described with respect to those parts. Description is omitted.

  In the second embodiment, as shown in FIG. 13, the first temperature sensor 10 is provided at the center lower portion of the heat exchanger 30 constituting the outdoor unit 40. The second temperature sensor 20 is installed at a location where the temperature is substantially the same as that of the first temperature sensor 10. The first temperature sensor 10 includes a thermistor sensor and has a structure in which changes in temperature measurement values are suppressed even when salt is attached. In addition, the second temperature sensor 20 includes a thermistor sensor, and an externally exposed electrode 21 that is exposed to the outside air is connected and integrated in parallel, and salt is attached to the externally exposed electrode. A structure whose temperature measurement value changes is used.

  In the second embodiment, the temperature difference between the temperature value T1 obtained from the first temperature sensor 10 and the temperature value T2 obtained from the second temperature sensor 20 is based on the same principle as in the first embodiment. In addition to estimating the amount of salt attached from ΔT, the corrosion level (corrosion progress level) of the heat exchanger is diagnosed.

  In addition, the output from the 1st temperature sensor 10 and the 2nd temperature sensor 20 is sent to the outdoor side control part 70 similarly to Example 1, and in this outdoor side control part 70 or the remote monitoring apparatus 72 (FIG. 7), and the amount of salt attached is calculated from the temperature difference ΔT between the first temperature sensor 10 and the second temperature sensor 20.

  Moreover, when employ | adopting this Example 2, it is necessary to make the said 1st temperature sensor 10 and the said 2nd temperature sensor 20 into a structure as shown, for example in FIGS.

  FIG. 14 is a structural diagram showing the first temperature sensor 10 shown in FIG. The first temperature sensor 10 is configured such that the thermistor sensor 10 ′ is a chip thermistor, and the chip thermistor 10 ′ is installed on the insulating substrate 22 and sealed with a covering material 25. Reference numeral 24 is a connection pad, and 26 is a lead wire. By comprising in this way, the 1st temperature sensor 10 becomes a structure where the change of a temperature measurement value is suppressed even if salt content adheres. In addition, by adopting a chip thermistor as the thermistor sensor 10 ', a small temperature sensor can be realized.

  FIG. 15 is a structural diagram showing the second temperature sensor 20 shown in FIG. The second temperature sensor 20 is manufactured by combining the externally exposed electrodes 21. That is, a chip thermistor similar to the first temperature sensor 10 is installed as a thermistor sensor 20 ′ below the insulating substrate 22, and the chip thermistor 20 ′ is configured to be resin-sealed on the insulating substrate 22 with the covering material 25. ing. An exposed electrode 23 of the external exposed electrode 21 is installed on the insulating substrate 22. The exposed electrode 23 and the chip thermistor 20 ′ are connected in parallel and connected to the lead wire 26 at the connection pad 24.

  By configuring the second temperature sensor 20 as shown in FIG. 15, a chip thermistor is employed as the thermistor sensor 20 ′ similarly to the first temperature sensor 10, so that the temperature sensor unit can be reduced in size. Moreover, since the externally exposed electrode 21 is also integrated, the second temperature sensor 20 can be easily attached.

  By configuring the second temperature sensor 20 as shown in FIG. 15, a chip thermistor is employed as the thermistor sensor 20 ′ similarly to the first temperature sensor 10, so that the temperature sensor unit can be reduced in size. Moreover, since the externally exposed electrode 21 is also integrated, the second temperature sensor 20 can be easily attached.

FIG. 16 is a structural diagram showing an example of an integrated temperature sensor 27 in which the first temperature sensor 10 and the second temperature sensor 20 shown in FIG. 13 are integrated.
As shown in FIG. 16, a thermistor sensor (chip thermistor) 10 ′ constituting the first temperature sensor 10 is installed below the insulating substrate 22 and the thermistor sensor (chip thermistor) constituting the second temperature sensor 20. ) 20 'is also installed. These thermistor sensors 10 ′ and 20 ′ are preferably configured to be resin-sealed with a covering material, similarly to those shown in FIGS. 14 and 15. The thermistor sensor 10 ′ is connected to the lead wire 26 at the connection pad 24.

  An exposed electrode 23 of the external exposed electrode 21 is installed on the insulating substrate 22. The exposed electrode 23 and the chip thermistor 20 ′ are connected in parallel and connected to the lead wire 26 at the connection pad 24. As the exposed electrode 23, the exposed electrode 23 ′ shown in FIG. 6 may be used.

  Thus, by using the integrated temperature sensor 27 in which the first temperature sensor 10 and the second temperature sensor 20 are integrated, the configuration of the corrosion diagnosis apparatus can be further reduced in size, and strip-shaped straight fins are employed. Not only the heat exchanger but also a heat exchanger employing corrugated fins can be easily attached.

  According to the second embodiment described above, the temperature at the center lower portion of the heat exchanger 30 of the outdoor unit 40 that has been found to be particularly fast in the field test is directly measured by the first and second temperature sensors 10. , 20 can be measured. For this reason, it is possible to obtain a corrosion diagnostic apparatus with higher accuracy than in the first embodiment.

  According to each embodiment of the present invention described above, it becomes possible to estimate the corrosion level of an aluminum heat exchanger constituting an air conditioner, particularly a parallel flow type heat exchanger, and refrigerant leakage due to corrosion can be estimated in advance. It is possible to obtain an air conditioner that can be avoided and a corrosion diagnosis device for a heat exchanger for the air conditioner. In addition, since the temperature sensor originally installed in the outdoor unit can be used as the first temperature sensor of the corrosion diagnostic apparatus, the corrosion diagnostic apparatus can be realized at low cost.

In addition, this invention is not limited to the Example mentioned above, Various modifications are included. Further, the above-described embodiments have been described in detail for easy understanding in the present invention, and are not necessarily limited to those having all the configurations described. For example, the externally exposed electrode 21 and the first and second temperature sensors 10 and 20 in the second embodiment are not necessarily limited to being installed at the center lower portion of the heat exchanger 30, and the first temperature sensor 10 and the second temperature sensor If the sensor 20 and the externally exposed electrode 21 have the same temperature environment, the sensor 20 and the externally exposed electrode 21 may be installed at other portions of the heat exchanger, inside or outside the outdoor unit 40. Moreover, in the said Example, although the output value from the 1st, 2nd temperature sensors 10 and 20 is converted into a temperature value, a temperature difference is calculated | required, and the amount of salt deposits is estimated based on this temperature difference. However, it is not always necessary to convert the output value into a temperature value. The output value (for example, the detected resistance value) itself is used to determine the difference between the output values, and based on this difference, the amount of salt can be estimated. good.
Furthermore, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

10: 1st temperature sensor, 10 ': Thermistor sensor (chip thermistor),
15: Water film
20: second temperature sensor, 20 ': thermistor sensor (chip thermistor),
21: outside air exposed electrode, 22, 22 ′: insulating substrate, 23, 23 ′: exposed electrode,
24, 24 ': connection pad, 25, 25': coating material, 26: lead wire,
27: Integrated temperature sensor, 28: Cable,
30: Heat exchanger, 31, 32: Refrigerant header, 33: Flat tube,
34, 35: fin (34: strip-shaped straight fin, 35: corrugated fin),
34a: slit part, 34b: uneven part,
40: outdoor unit, 50: compressor, 60: blower fan,
70: outdoor side control unit, 71 (71a, 71b, 71c, 71d): terminal,
72: Remote monitoring device, 73: Network.

Claims (2)

An air conditioner including an outdoor unit having a heat exchanger, a first temperature sensor that measures the temperature of an arbitrary location of the outdoor unit, and a second that detects the temperature of substantially the same location as the first temperature sensor A temperature sensor and an exposed electrode provided exposed to the outside air and an external exposed electrode connected in parallel to the second temperature sensor;
The point in time when the difference between the output value from the first temperature sensor and the output value from the second temperature sensor starts to increase is defined as the relative humidity at which salinity begins to deliquesce, and the absolute humidity is obtained from the temperature and relative humidity at the start of deliquescent. Then, a change in relative humidity is calculated from the change in absolute humidity and temperature, and based on the difference between the relative humidity and the output value of the first temperature sensor and the second temperature sensor in the environment of the relative humidity, the heat A method for diagnosing corrosion of a heat exchanger for an air conditioner, characterized by estimating an amount of salt attached to the exchanger. 2. The corrosion diagnosis method for a heat exchanger for an air conditioner according to claim 1 , wherein the estimated amount of adhering salt and “temperature> 0 ° C., relative humidity> 80%” where the heat exchanger is placed. A corrosion diagnosis method for a heat exchanger for an air conditioner, characterized by diagnosing the corrosion level of the heat exchanger from a time (wetting time) that satisfies an environment.

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