JP2010038525A - Coolant leak detection device and refrigeration device provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coolant leakage detection device which can accurately determine whether a coolant leak occurs even when sensors are affected by humidity, and to provide a refrigeration device. <P>SOLUTION: This coolant leak detection device 7 is provided with a first sensor 71, a second sensor 72, a calculation unit 73, and a detection unit 74. The electrostatic capacitance Cx of the first sensor 71 changes due to the adsorption of the refrigerator oil in an air conditioning device 1 and specific electrostatic capacitance-changing factors excluding the refrigerator oil. The electrostatic capacitance Cn of the second sensor 72 changes due to specific electrostatic capacitance-changing factors but not by the adsorption of the refrigerator oil. The calculation unit 73 calculates the degree of change in the electrostatic capacitance caused by the adsorption of the refrigerator oil on the basis of a first difference of the output of the first sensor 71 and the output of the second sensor 72. The detection unit 74 detects coolant leaks in the air conditioning device 1 on the basis of the degree of change in the electrostatic capacitance calculated by the calculation unit 73. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerant leak detection device and a refrigeration apparatus including the same.

  As a technique for detecting refrigerant leakage in the refrigerant circuit of the refrigeration apparatus, for example, as disclosed in Patent Document 1, the refrigerant amount enclosed in the refrigerant circuit is calculated from various operation state quantities, and the calculated refrigerant amount A technique for detecting refrigerant leakage based on the above is known.

In addition, as another technique for detecting refrigerant leakage, there is a technique for detecting refrigerant leakage using a sensor of a type in which the electrostatic capacity changes due to adsorption of refrigeration oil in the refrigerant.
JP 2007-163099 A

  However, in the above sensor, when the sensitivity is improved, the influence of humidity is unavoidable. That is, when the humidity changes, the amount of water vapor contained in the sensor electrode changes, so the output of the sensor (specifically, the output based on the capacitance) changes not only due to the refrigerating machine oil but also the influence of water vapor. Resulting in.

  Accordingly, the present invention provides a refrigerant leakage detection device that can accurately know whether or not refrigerant leakage has occurred even when the sensor is affected by humidity, and a refrigeration apparatus including the refrigerant leakage detection device. Objective.

  The refrigerant leakage detection device according to the first aspect includes a first sensor, a second sensor, a calculation unit, and a detection unit. The capacitance of the first sensor changes as a result of adsorption of the refrigeration oil in the refrigeration apparatus and a predetermined capacitance change factor other than the refrigeration oil. In the second sensor, the adsorption of the refrigerating machine oil does not act, and the capacitance changes due to the action of a predetermined capacitance change factor. The calculation unit calculates a change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference between the output of the first sensor and the output of the second sensor. The detection unit detects refrigerant leakage in the refrigeration apparatus based on the capacitance change calculated by the calculation unit.

  The predetermined capacitance change factor includes humidity (that is, water vapor), temperature, and secular change. According to this refrigerant leak detection device, both the first sensor and the second sensor are subjected to capacitance change factors such as humidity, but the second sensor is not subjected to adsorption of refrigerating machine oil, and the first sensor Adsorption of refrigerating machine oil acts on. The calculation unit calculates a change in capacitance due to the adsorption of the refrigerating machine oil from the first difference between the outputs of these sensors, and the detection unit detects refrigerant leakage based on the change in capacitance. In other words, the refrigerant leak detection device cancels the change in capacitance based on the capacitance change factor such as humidity by the first sensor and the second sensor, and only the change in capacitance based on the adsorption of the refrigerating machine oil. Can be sought. Thereby, it is possible to accurately know whether or not refrigerant leakage has occurred based only on the change in capacitance of the first sensor based on the adsorption of the refrigerating machine oil.

  A refrigerant leakage detection device according to a second aspect is the refrigerant leakage detection device according to the first aspect, wherein the first sensor and the second sensor are connected in a bridge shape.

  In this refrigerant leak detection device, each sensor is connected in a bridge shape. For example, each one end part of a 1st sensor and a 2nd sensor is connected directly, and each other end part is connected via the means which can detect an electric current. If a difference occurs between the capacitance of the first sensor and the capacitance of the second sensor, a current corresponding to the difference flows on the means capable of detecting the current. The first difference between the output of one sensor and the output of the second sensor can be easily obtained.

  A refrigerant leakage detection device according to a third aspect of the present invention is the refrigerant leakage detection device according to the first aspect, further comprising a chopping unit and a noise removal unit. The chopping unit chops the output of the first sensor and the output of the second sensor at a predetermined frequency to generate a first signal. The noise removing unit removes noise from the first signal generated by the chopping unit. And a calculating part calculates | requires a 1st difference based on the 1st signal after noise was removed by the noise removal part.

  When the change in capacitance due to adsorption of refrigerating machine oil is small, the first difference between the outputs of both sensors is buried in noise, making it difficult to simply extract only the change in capacitance due to adsorption of refrigerating machine oil. End up. However, according to this refrigerant leak detection device, after the output based on the capacitance of each sensor is chopped at a predetermined frequency, noise is removed from the output after chopping (that is, the first signal). Therefore, by calculating the capacitance change due to the adsorption of the refrigerating machine oil using the first difference obtained based on the first signal, the capacitance change due to the adsorption of the refrigerating machine oil without being influenced by noise. Only the minute can be taken out with high accuracy, and refrigerant leakage can be detected more accurately.

  The refrigerant leakage detection device according to a fourth aspect of the present invention is the refrigerant leakage detection device according to the third aspect, wherein the predetermined frequency is a frequency different from the frequency of the noise of the first signal.

  Thereby, the amplitude and noise portion of the first signal corresponding to the first difference can be separated.

  The refrigerant leakage detection device according to a fifth aspect of the present invention is the refrigerant leakage detection device according to the first aspect, further comprising a first oscillating unit, a second oscillating unit, a mixing unit, a takeout unit, and a counting unit. The first oscillation unit oscillates at a frequency corresponding to the capacitance of the first sensor. The second oscillation unit oscillates at a frequency corresponding to the capacitance of the second sensor. The mixing unit mixes the output of the first oscillating unit and the output of the second oscillating unit to generate a second signal. The extraction unit extracts a signal whose second signal value is greater than or equal to a threshold value from the second signals generated by the mixing unit. The count unit counts the extraction results obtained by the extraction unit. And a calculating part calculates | requires a 1st difference based on the count result by a counting part.

  According to this refrigerant leak detection device, a signal oscillated at a frequency corresponding to the capacitance of each sensor is mixed to generate a second signal, and a signal having a value equal to or greater than a threshold value is included in the second signal. It is taken out. Since the number of signals is accumulated by counting the extracted signals, it is possible to accurately grasp the frequency of the extracted signals. Accordingly, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy by the first difference obtained based on the count result by the counting unit, and the refrigerant leakage can be detected more accurately.

  A refrigerant leakage detection device according to a sixth aspect of the present invention is the refrigerant leakage detection device according to the first aspect, further comprising a third oscillation unit, a fourth oscillation unit, and an up / down counting unit. The third oscillation unit oscillates at a frequency corresponding to the capacitance of the first sensor. The fourth oscillation unit oscillates at a frequency corresponding to the capacitance of the second sensor. The up / down count unit up-counts the output of the third oscillation unit and down-counts the output of the fourth oscillation unit. And a calculating part calculates | requires a 1st difference based on the count value by an up-down count part.

  According to this refrigerant leak detection device, the up / down counting unit counts up the signal oscillated according to the capacitance of the first sensor and down-counts the signal oscillated according to the capacitance of the second sensor. . The count value by the up / down count unit is the number of pulses corresponding to the difference between the frequency according to the capacitance of the first sensor and the frequency according to the capacitance of the second sensor. The difference can be obtained. By obtaining the change in capacitance based on the first difference thus obtained, only the change in capacitance due to the adsorption of the refrigerating machine oil can be extracted with high accuracy. Therefore, refrigerant leakage can be detected more accurately.

  A refrigerant leakage detection device according to a seventh aspect is the refrigerant leakage detection device according to the sixth aspect, further comprising a selection unit. The selection unit selects either the output of the third oscillation unit or the output of the fourth oscillation unit. Either the output of the third oscillation unit or the output of the fourth oscillation unit selected by the selection unit is input to the up / down count unit.

  According to this refrigerant leakage detection device, either the output of the third oscillating unit or the output of the fourth oscillating unit is input to the up / down counting unit. That is, the output of the third oscillating unit and the output of the fourth oscillating unit are not simultaneously input to the up / down counting unit. Therefore, the up / down counting unit can reliably perform the operation of up-counting the output of the third oscillation unit and down-counting the output of the fourth oscillation unit, and obtain an accurate count value for obtaining the first difference. Be able to get.

  A refrigerant leakage detection device according to an eighth aspect of the present invention is the refrigerant leakage detection device according to the sixth or seventh aspect, further comprising a reset unit. A reset part resets the count value by an up-down count part for every predetermined period.

  Thereby, the calculating part can obtain | require the 1st difference of the output of a 1st sensor and the output of a 2nd sensor with the count value before resetting.

  A refrigerant leakage detection device according to a ninth aspect is the refrigerant leakage detection device according to the first aspect, wherein the first reset unit, the second reset unit, the first count unit, the second count unit, and the difference calculation unit, Is further provided. The first reset unit outputs a first reset signal based on a time constant determined by the capacitance of the first sensor. The second reset unit outputs a second reset signal based on a time constant determined by the capacitance of the second sensor. The first counting unit counts a pulse signal having a predetermined frequency and stops counting the pulse signal based on the first reset signal. The second count unit counts the pulse signal and stops counting the pulse signal based on the second reset signal. The difference calculation unit obtains a second difference in the number of counts counted until each of the first count unit and the second count unit stops counting the pulse signal. And a calculating part calculates | requires a 1st difference based on a 2nd difference.

  According to this refrigerant leak detection device, the first count unit counts the pulse signal until a reset is instructed by the first reset signal, and the second count unit until the reset is instructed by the second reset signal, Count pulse signals. Here, the first reset signal and the second reset signal are a signal based on the time constant determined from the capacitance of the first sensor and a signal based on the time constant determined from the capacitance of the second sensor, respectively. Therefore, the timing at which the first count unit and the second count unit stop counting is different. That is, the difference in the number of counts by each count unit corresponds to the difference in capacitance of each sensor. Therefore, the refrigerant leakage detection device can obtain the first difference from the second difference of the respective count numbers. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy, and refrigerant leakage can be detected more accurately.

  A refrigerant leakage detection device according to a tenth aspect of the present invention is the refrigerant leakage detection device according to the first aspect, further comprising a first timer unit, a second timer unit, and an interval calculation unit. After the time determined according to the capacitance of the first sensor elapses, the first timer unit outputs a first time elapse signal indicating that. After the time determined according to the capacitance of the second sensor has elapsed, the second timer unit outputs a second time elapsed signal indicating that. The interval calculation unit calculates the length of time during which any one of the first time lapse signal and the second time lapse signal is output from the first timer unit or the second timer unit. And a calculating part calculates | requires a 1st difference based on the length of time calculated by the space | interval calculation part.

  When the capacitance of each sensor is different, the time determined according to the capacitance of the first sensor and the time determined according to the capacitance of the second sensor are different. The timings at which the first and second time lapse signals indicating this start to output are also different. Therefore, the refrigerant leakage detection device is the length of time during which any one of the first time passage signal and the second time passage signal indicating the passage of each time is output, that is, the timing at which the first time passage signal starts to be output. And the first difference is obtained based on the difference between the timing at which the second elapsed time signal starts to be output. In other words, the length of time corresponds to the amount of change in capacitance due to adsorption of refrigeration oil, so only the amount of change in capacitance due to adsorption of refrigeration oil can be extracted with high accuracy, and refrigerant leakage can be more accurately performed. Can be detected.

  A refrigeration apparatus according to an eleventh aspect includes a refrigerant circuit and the refrigerant leakage detection apparatus according to any one of the first to tenth aspects. The refrigerant leakage detection device is disposed in or near a portion of the refrigerant circuit that detects refrigerant leakage.

  According to this refrigerant device, the refrigerant leakage detection device according to inventions 1 to 10 detects refrigerant leakage in the refrigerant circuit. Therefore, the same effects as those of the inventions 1 to 10 can be obtained.

  According to the refrigerant leakage detection device according to the first aspect of the present invention, it is possible to accurately know whether or not refrigerant leakage has occurred based only on the change in the capacitance of the first sensor based on the adsorption of refrigeration oil.

  According to the refrigerant leakage detection device of the second aspect of the present invention, the current corresponding to the difference between the capacitance of the first sensor and the capacitance of the second sensor flows on the means capable of detecting the current. Thus, the first difference between the output of the first sensor and the output of the second sensor can be easily obtained.

  According to the refrigerant leakage detection device according to the third, fifth, sixth, and ninth to tenth aspects, only the change in electrostatic capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy, and the refrigerant leakage can be detected more accurately. .

  According to the refrigerant leakage detection device according to the fourth aspect, the amplitude of the first signal corresponding to the first difference and the noise portion can be separated.

  According to the refrigerant leakage detection device of the seventh aspect, the up / down counting unit can reliably perform the operation of up-counting the output of the third oscillating unit and down-counting the output of the fourth oscillating unit. It is possible to obtain an accurate count value for obtaining.

  According to the refrigerant leakage detection device of the eighth aspect, the calculation unit can obtain the first difference between the output of the first sensor and the output of the second sensor based on the count value before being reset.

  According to the refrigeration apparatus of the eleventh aspect, the same effects as those of the first to tenth aspects can be achieved.

  Hereinafter, a refrigerant leakage detection apparatus according to the present invention and a refrigeration apparatus including the same will be described in detail with reference to the drawings.

<First Embodiment>
(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 as a first embodiment of a refrigeration apparatus according to the present invention. The air conditioner 1 of FIG. 1 is a so-called separate type air conditioner. The air conditioner 1 mainly includes a utilization unit 3, a heat source unit 4, and refrigerant communication pipes 5 and 6 that connect the utilization unit 3 and the heat source unit 4, and constitutes a vapor compression refrigerant circuit 2. Yes. The refrigerant circuit 2 is filled with a CFC refrigerant such as R12, an HCFC refrigerant such as R22, an HFC refrigerant such as R410A, an HC refrigerant such as propane, carbon dioxide, ammonia, or the like.

[Usage unit]
The usage unit 3 is installed on, for example, a ceiling, a ceiling surface, or a wall surface of an air-conditioning room, and mainly includes a usage-side heat exchanger 31, a usage-side fan 32, and a usage-side control unit 33.

  The use side heat exchanger 31 is one of the elements constituting the refrigerant circuit 2. One end of the use side heat exchanger 31 is connected to the refrigerant communication pipe 5, and the other end of the use side heat exchanger 31 is connected to the refrigerant communication pipe 6. Such use side heat exchanger 31 functions as a refrigerant heater during cooling operation to cool room air, and functions as a refrigerant cooler during heating operation to heat room air. Specifically, as the use-side heat exchanger 31, for example, a fin-and-tube heat exchanger configured by a heat transfer tube through which a refrigerant flows and a large number of fins can be cited.

  The use-side fan 32 is a fan for sucking room air into the use unit 3 and supplying the room air that has been sucked and heat-exchanged into the room. That is, the use side fan 32 can exchange heat between the indoor air and the refrigerant flowing through the use side heat exchanger 31. The use side fan 32 is rotationally driven by a fan motor 32a.

  The use side control unit 33 is a microcomputer composed of a CPU and a memory, and controls the operation of each device constituting the use unit 3. In addition, the usage-side control unit 33 can transmit and receive control signals and the like with a remote controller (not shown) for remotely operating the usage unit 3, and control signals with the heat source unit 4. Etc. can be transmitted and received.

[Heat source unit]
The heat source unit 4 is installed, for example, outside the air conditioning room, and mainly includes a compressor 41, a four-way switching valve 42, a heat source side heat exchanger 43, an expansion mechanism 44, a first closing valve 45, a second closing valve 46, a heat source. A side fan 47 and a heat source side control unit 48 are provided. In particular, the compressor 41, the four-way switching valve 42, the heat source side heat exchanger 43, the expansion mechanism 44, and the first and second closing valves 45 and 46 are elements constituting the refrigerant circuit 2.

  The compressor 41 is for compressing the refrigerant. The compressor 41 according to the present embodiment is a so-called hermetic compressor in which a compressor motor 41a is incorporated. The compressor 41 can perform a lubricating compression operation with refrigeration oil, but this refrigeration oil is enclosed in a refrigerant flowing through the refrigerant circuit 2.

  The four-way switching valve 42 is for switching the flow direction of the refrigerant. During the cooling operation, the four-way switching valve 42 causes the heat source side heat exchanger 43 to function as a cooler for the refrigerant compressed by the compressor 41, and the use side heat exchanger 31 is cooled in the heat source side heat exchanger 43. In order to function as a refrigerant heater, the discharge side of the compressor 41 and one end of the heat source side heat exchanger 43 are connected, and the suction side of the compressor 41 and the refrigerant communication pipe 6 side (that is, the second closing valve 46). (Refer to the solid line of the four-way switching valve 42 in FIG. 1). Further, the four-way switching valve 42 causes the use side heat exchanger 43 to function as a cooler for the refrigerant compressed by the compressor 41 during the heating operation, and the heat source side heat exchanger 43 is used in the use side heat exchanger 31. In order to function as a heater for the cooled refrigerant, the discharge side of the compressor 41 and the refrigerant communication pipe 6 side (that is, the second closing valve 46) are connected, and the suction side and the heat source side heat exchanger of the compressor 41 are connected. 43 is connected to one end (see the dotted line of the four-way selector valve 42 in FIG. 1).

  One end of the heat source side heat exchanger 43 is connected to the four-way switching valve 42, and the other end of the heat source side heat exchanger 43 is connected to the expansion mechanism 44. The heat source side heat exchanger 43 functions as a refrigerant cooler using outdoor air as a heat source during cooling operation, and functions as a refrigerant heater using outdoor air as a heat source during heating operation. Specifically, as the heat source side heat exchanger 43, for example, a fin-and-tube heat exchanger can be cited as with the use side heat exchanger 31.

  The expansion mechanism 44 is for depressurizing the high-pressure refrigerant. Examples of the expansion mechanism 44 include an electric expansion valve that depressurizes high-pressure refrigerant during cooling operation and heating operation.

  The first and second closing valves 45 and 46 are valves provided at connection ports of external devices and pipes (specifically, refrigerant communication pipes 5 and 6). The first closing valve 45 is connected to the expansion mechanism 44, and the second closing valve 46 is connected to the four-way switching valve 42.

  The heat source side fan 47 is a fan for sucking outdoor air into the heat source unit 4 and discharging outdoor air after being sucked and subjected to heat exchange. That is, the heat source side fan 47 can exchange heat between the outdoor air and the refrigerant flowing through the heat source side heat exchanger 43. The heat source side fan 47 is rotationally driven by a fan motor 47a.

  The heat source side control unit 48 is a microcomputer composed of a CPU and a memory, and controls the operation of each device constituting the heat source unit 4. Further, the heat source side control unit 48 can transmit and receive control signals and the like to and from the use side control unit 33 in the use unit 3.

(2) Configuration of Refrigerant Leak Detection Device The refrigerant circuit 2 in the air conditioning apparatus 1 described above is provided with a plurality of refrigerant leak detection devices 7 for detecting the refrigerant leaking outside the refrigerant circuit 2. More specifically, the refrigerant leak detection device 7 is provided in or near the portion of the refrigerant circuit 2 where there is a high risk of refrigerant leakage. Here, as a part with high possibility of refrigerant | coolant leakage, the connection part of piping which comprises the refrigerant circuit 2, and various apparatuses, such as the brazing location and flare nut connection location which exist in various places of the refrigerant circuit 2, for example And a connecting part between the refrigerant communication pipe and the refrigerant communication pipe. In the present embodiment, as shown in FIG. 1, the refrigerant leakage detection device 7 is connected to or near each pipe joint that connects the first closing valve 45 and the refrigerant communication pipe 5, the second closing valve 46 and the refrigerant communication pipe 6. Are arranged at or near the pipe joints connecting the use unit 3 and the refrigerant communication pipe 5, or near the pipe joints connecting the use unit 3 and the refrigerant communication pipe 6, respectively. Take the case where it is. In addition, since each refrigerant | coolant leak detection apparatus 7 arrange | positioned on the refrigerant circuit 2 has the respectively same structure, in FIG. 1, the same code | symbol is attached | subjected.

  Here, as the timing at which the refrigerant leakage detection device 7 is provided in the air conditioner 1, when the air conditioner 1 is a new one, it is provided in advance from the time of factory shipment of the air conditioner 1, or the air conditioner 1 is provided. It can be provided when the device 1 is installed on site. Moreover, when the air conditioning apparatus 1 is an existing apparatus that does not have the refrigerant leakage detection device 7, the refrigerant leakage detection device 7 can be retrofitted during maintenance or the like.

  As shown in FIG. 2, the refrigerant leakage detection device 7 according to this embodiment includes a first sensor 71, a second sensor 72, a calculation unit 73, and a detection unit 74.

[First sensor and second sensor]
As shown in FIGS. 2 and 3, the first sensor 71 is disposed at or near the pipe joint of the refrigerant circuit 2 so as to be affected by the refrigeration oil leaking from the refrigerant circuit 2. . The first sensor 71 is covered with a film 81, and a part of the wiring extending from the first sensor 71 is fixed to the refrigerant pipe by a fixing member 82 made of a band or an adhesive tape. Thereby, although the 2nd sensor 72 is arrange | positioned in the 1st sensor 71 vicinity, since the refrigerating machine oil which leaked from the refrigerating circuit 2 does not flow out from the film 81 which covers the 1st sensor 71 outside, the 2nd sensor 72 is not affected by refrigerating machine oil.

  Next, the configuration of the first sensor 71 and the second sensor 72 will be described. In addition, since the 1st sensor 71 and the 2nd sensor 72 have the respectively same structure, below, it demonstrates taking the 1st sensor 71 as an example using FIG.

  The first sensor 71 is composed of two electrodes 71a and 71b provided with a gap therebetween. Each of the electrodes 71a and 71b is a plate-like member made of a conductive material, and is in a state where a predetermined interval is maintained by a spacer member 71c made of an insulating material. That is, the first sensor 71 can be said to have a flat plate structure. Examples of the conductive material for the electrodes 71a and 71b include metals having relatively high conductivity such as iron, copper, and aluminum. Examples of the insulating material for the spacer member 71c include materials having relatively high insulating properties such as synthetic resin and ceramic. In particular, since the first sensor 71 is covered with the film 81 as described above, the refrigerating machine oil tends to stay in the space S between the two electrodes 71a and 71b.

  In the first sensor 71 having the above-described configuration, the capacitance Cx changes due to the adsorption of the refrigeration oil flowing on the refrigerant circuit 2 and the predetermined capacitance change factor other than the refrigeration oil. In addition, the second sensor 72 does not act on the adsorption of the refrigerating machine oil, and the capacitance Cn changes when only a predetermined capacitance change factor acts. Here, examples of the predetermined capacitance change factor include humidity (that is, water vapor), temperature, and secular change. That is, the first sensor 71 adsorbs the refrigeration oil leaking from the refrigerant pipe and is affected by the humidity, temperature, and the like around the refrigerant pipe, so that the capacitance Cx changes. On the other hand, the second sensor 72 is not affected by the refrigerating machine oil as already described, but similarly to the first sensor 71, the second sensor 72 is affected by the humidity, temperature, and the like around the refrigerant pipe. Cn changes.

  Further, as shown in FIG. 5, the first sensor 71 and the second sensor 72 according to the present embodiment are connected in a bridge shape together with capacitors 83 and 84 having both constant capacitances “C”. More specifically, one end of the first sensor 71 and one end of the second sensor 72 are directly connected, and the other end of the first sensor 71 and the other end of the second sensor are connected via a current detection circuit 85. Connected. Both ends of the current detection circuit 85 are connected to one end portions of the capacitors 83 and 84, and the other end portions of the capacitors 83 and 84 are directly connected to each other. In addition, the connection part of sensors 71 and 72 is connected to GND. The connection portion between the capacitors 83 and 84 is connected to the output of the power source, and the voltage V is applied. In this way, the first sensor 71 and the second sensor 72 are connected in a bridge shape, so that the capacitance Cx of the first sensor 71 and the electrostatic capacitance of the second sensor 72 are shown in A1 in FIG. When the capacitance Cn is equivalent (Cx = Cn), no current flows through the current detection circuit 85. On the other hand, as indicated by A2 in FIG. 6, when the capacitance Cx of the first sensor 71 and the capacitance Cn of the second sensor 72 are not equivalent (Cx ≠ Cn), the current detection circuit 85 has a current. Begins to flow. FIG. 6 shows an example of the capacitance Cx of the first sensor 71 and the capacitance Cn of the second sensor 72 that change over time.

[Calculation section]
The calculation unit 73 is connected to the output of the current detection circuit 85. The computing unit 73 computes the change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference between the output of the first sensor 71 and the output of the second sensor 72. That is, the first sensor 71 outputs a value based on the capacitance Cx according to the capacitance change factor together with the adsorption of the refrigerating machine oil, and the second sensor 72 generates a static value according to only the capacitance change factor. A value based on the capacitance Cn is output. Therefore, the first difference between the output of the first sensor 71 and the output of the second sensor 72 cancels out the capacitance change due to the capacitance change factor such as humidity, and only the capacitance change due to the refrigerator oil. The corresponding value is obtained (that is, B in FIG. 6). Therefore, the calculation unit 73 calculates the amount of change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference, so that the amount of change in the refrigerating machine oil not including the change due to the capacitance change factor such as humidity is included. Therefore, only the change in capacitance can be accurately obtained.

  Here, in the present embodiment, since the first sensor 71 and the second sensor 72 are connected in a bridge shape as shown in FIG. 5, the calculation unit 73 outputs the output of the first sensor 71 and the second sensor 72. Based on the current value of the current detection circuit 85 corresponding to the first difference from the output of, the change in capacitance is calculated. That is, if the current value of the current detection circuit 85 is approximately 0 A, the calculation unit 73 determines that the capacitance Cx of the first sensor 71 and the capacitance Cn of the second sensor are equal (Cx = Cn. In FIG. 6A1), the change in electrostatic capacitance due to the adsorption of refrigerating machine oil in the first sensor 71 is calculated as “0”. When the current value of the current detection circuit 85 is not approximately 0 A, the difference between the capacitance Cx of the first sensor 71 and the capacitance Cn of the second sensor (that is, Cx− 6, since the current corresponding to B) in FIG. 6 is flowing, the calculation unit 73 is based on the current value of the current detection circuit 85, and the capacitance change due to the adsorption of the refrigeration oil in the first sensor. Ask for.

  Note that the calculation unit 73 may be configured by a calculation circuit or a microcomputer including a memory and a CPU as long as it can calculate a change in electrostatic capacitance due to adsorption of refrigeration oil. . In the present embodiment, a case where the calculation unit 73 is configured by a microcomputer is taken as an example.

(Detector)
The detection unit 74 detects refrigerant leakage based on the change in capacitance calculated by the calculation unit 73. Specifically, if the calculation result by the calculation unit 73 is “0”, the detection unit 74 determines that the refrigerant has not leaked. If the calculation result by the calculation unit 73 is not “0”, the detection unit 74 determines that the refrigerant is leaking and calculates the amount of refrigerating machine oil leaking based on the calculation result. As shown in FIG. 2, the detection result by the detection unit 74 is sent to the use side control unit 33 and the heat source side control unit 48 and is used for controlling the use unit 3 and the heat source unit 4.

  Similarly to the calculation unit 73, the detection unit 74 may be configured with a detection circuit or a microcomputer including a memory and a CPU as long as refrigerant leakage can be detected. In this embodiment, the case where the detection part 74 is comprised with the microcomputer is taken for an example.

(3) Effect (A)
According to the refrigerant leakage detection device 7 according to the present embodiment, both the first sensor 71 and the second sensor 72 are subjected to a capacitance change factor such as humidity, but the second sensor 72 is adsorbed by refrigerating machine oil. Does not act, and refrigeration oil adsorption acts on the first sensor 71. The calculation unit 73 calculates a change in capacitance due to the adsorption of the refrigerating machine oil from the first difference between the outputs of the sensors 71 and 72, and the detection unit 74 detects refrigerant leakage based on the change in capacitance. That is, the refrigerant leak detection device 7 uses the first sensor 71 and the second sensor 72 to cancel the capacitance change based on the capacitance change factor, and only the capacitance change based on the adsorption of the refrigerating machine oil. Can be obtained (see B in FIG. 6). Thereby, it is possible to accurately know whether or not refrigerant leakage has occurred based only on the change in capacitance of the first sensor 71 based on the adsorption of the refrigerating machine oil.

(B)
Moreover, in the refrigerant | coolant leak detection apparatus 7 which concerns on this embodiment, the 1st sensor and the 2nd sensors 71 and 72 are connected in bridge shape. That is, each one end of the first sensor 71 and the second sensor 72 is directly connected, and each other end is connected via the current detection circuit 85. As a result, when a difference occurs between the capacitance Cx of the first sensor 71 and the capacitance Cn of the second sensor 72, a current corresponding to this difference flows to the current detection circuit 85. The first difference between the output of the first sensor 71 and the output of the second sensor 72 can be easily obtained by the value.

<Second Embodiment>
Next, the refrigerant leak detection apparatus 107 according to the second embodiment of the present invention will be described. As in the first embodiment, the refrigerant leak detection device 107 according to the present embodiment is used as a refrigerant leak detection device in the refrigerant circuit of the air conditioning apparatus. This device is effective when it is relatively small. In addition, since the structure of the air conditioning apparatus in which the refrigerant | coolant leak detection apparatus 107 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. Is omitted, and the configuration of the refrigerant leak detection device 107, which is a feature of the present embodiment, will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 7 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 107 according to the present embodiment. 7 includes a first sensor 171, a second sensor 172, a first voltage conversion circuit 173, a second voltage conversion circuit 174, a chopping circuit 175, a noise removal circuit 176, a calculation unit 177 and a detection unit 178. Is provided.

  The first sensor 171, the second sensor 172, and the detection unit 178 have the same configuration as the first sensor 71, the second sensor 72, and the detection unit 74 that are given the same names in the first embodiment. Therefore, detailed description is omitted. Below, the 1st and 2nd voltage conversion circuits 173 and 174, the chopping circuit 175, the noise removal circuit 176, and the calculating part 177 are demonstrated.

[First voltage conversion circuit and second voltage conversion circuit]
The input terminal of the first voltage conversion circuit 173 is connected to the first sensor 171, and the input terminal of the second voltage conversion circuit 174 is connected to the second sensor 172. The first voltage conversion circuit 173 converts the output of the first sensor 171 into a voltage, and the second voltage conversion circuit 174 converts the output of the second sensor 172 into a voltage. In other words, the first voltage conversion circuit 173 outputs according to the capacitance Cx of the first sensor 171, that is, output according to the capacitance Cx changed by the adsorption of the refrigerating machine oil and the capacitance change factor. To voltage. The second voltage conversion circuit 174 converts the output corresponding to the capacitance Cn of the second sensor 172, that is, the output corresponding to the capacitance Cn changed by only the capacitance change factor, into a voltage. Outputs of the voltage conversion circuits 173 and 174 are input to the chopping circuit 175.

[Chopping circuit]
The chopping circuit 175 has two input terminals, and each input terminal is connected to the output terminal of the first voltage conversion circuit 173 and the output terminal of the second voltage conversion circuit 174. The chopping circuit 175 outputs the output of the first sensor 171 converted into a voltage by the first voltage conversion circuit 173 and the output of the second sensor 172 converted into a voltage by the second voltage conversion circuit 174 at a predetermined frequency (hereinafter referred to as “the frequency”). And chopping frequency fc). FIG. 8 shows the first signal Sg1 generated by being chopped by the chopping circuit 175. In FIG. 8, for simplicity of explanation, the vertical axis represents the capacitance rather than the voltage. As shown in FIG. 8, the first signal Sg1 generated by the chopping circuit 175 is obtained by converting the output of the first sensor 171 into a voltage (Cx in FIG. 8) and the output of the second sensor 172 as a voltage. The converted signal (Cn in FIG. 8) is a signal that appears alternately at predetermined intervals. When the first signal Sg1 is represented by a frequency distribution in which the horizontal axis represents the frequency and the vertical axis represents the amplitude of the first signal Sg1 (here, for the sake of convenience of description, the capacitance), a graph as shown in FIG. Is obtained. Focusing on the frequency distribution of FIG. 9, an amplitude component corresponding to the difference between the capacitance Cx of the first sensor 171 and the capacitance Cn of the second sensor 172 appears in the chopping frequency band (FIG. 9). p2). Furthermore, in the frequency distribution of FIG. 9, peaks p1 and p3 of various noise components on the first signal Sg1 appear in the frequency portion of each noise.

  Here, the chopping frequency fc according to the present embodiment may be a frequency different from the frequency of the noise of the first signal Sg1. For example, the chopping frequency fc is predicted to be the first signal Sg1 based on the outputs of the first sensor 171 and the second sensor 172, the experimental results when the output of each sensor is chopped at an arbitrary frequency, or the like. Is determined to avoid the noise frequency. In this way, the chopping circuit 175 performs the chopping of each output at a frequency different from the frequency of the noise of the first signal Sg1, thereby obtaining the capacitance Cx of the first sensor 171 and the capacitance Cn of the second sensor 172. It is possible to separate the amplitude of the signal corresponding to the difference between them (ie, p2 in FIG. 9) and the peaks p1 and p3 caused by the noise component.

[Noise elimination circuit]
The input terminal of the noise removal circuit 176 is connected to the output terminal of the chopping circuit 175. The noise removal circuit 176 removes noise from the first signal Sg1 generated by the chopping circuit 175. Specifically, the noise removal circuit 176 is configured by a so-called low-pass filter that cuts a signal having a frequency higher than the cutoff frequency and passes a signal having a frequency lower than the cutoff frequency. The cut-off frequency is set higher than the chopping frequency fc of the chopping circuit 175. In order to remove noise having a frequency lower than the chopping frequency fc, a high-pass filter or a band-pass filter is used as the noise removal circuit 176.

  According to such a noise removal circuit 176, since the noise component including the peaks p1 and p3 in FIG. 9 is cut from the first signal Sg1, the electrostatic capacitance Cx of the first sensor 171 and the electrostatic capacitance of the second sensor 172. A signal component corresponding to a difference from the capacitance Cn (that is, a component including the peak p2 at the chopping frequency fc) is extracted.

[Calculation section]
The calculation unit 177 is connected to the output terminal of the noise removal circuit 176. The calculation unit 177 calculates the first difference based on the first signal Sg1 ′ after the noise is removed by the noise removal circuit 176, and calculates the change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference. To do. Specifically, the calculation unit 177 obtains the amplitude component Yf from the component (FIG. 9) including the peak p2 in the chopping frequency fc extracted by the noise removal circuit 176, and uses this as the first difference. Then, the calculation unit 177 obtains a change in capacitance based on the first difference, and outputs this to the detection unit 178.

  In addition, the calculating part 177 may be comprised with the circuit for a calculation similarly to the calculating part 73 which concerns on 1st Embodiment, or may be comprised with the microcomputer which consists of memory and CPU. In this embodiment, the case where the calculating part 177 is comprised with the microcomputer is taken as an example.

(2) Effect (A)
If the change in capacitance due to the adsorption of the refrigerating machine oil is small, the first difference between the outputs of the sensors 171 and 172 is buried in noise, and it is difficult to simply extract only the change in the capacitance due to the adsorption of the refrigerating machine oil. End up. However, according to the refrigerant leak detection device 107 according to the present embodiment, the first signal Sg1 that is the output after chopping after the output based on the capacitances Cx and Cn of the sensors 171 and 172 is chopped at the chopping frequency fc. The noise is removed by the noise removal circuit 176. Accordingly, the calculation unit 177 calculates the capacitance change due to the adsorption of the refrigerating machine oil by using the first difference obtained based on the first signal Sg1, so that the refrigerating machine oil is not affected by noise. Only the change in capacitance due to adsorption can be extracted with high accuracy. Therefore, refrigerant leakage can be detected more accurately.

(B)
Further, since the chopping frequency fc is a frequency different from the noise frequency in the first signal Sg1, the chopping circuit 175 separates the amplitude and the noise portion of the first signal Sg1 corresponding to the first difference. become.

<Third Embodiment>
Next, the refrigerant leakage detection device 207 according to the third embodiment of the present invention will be described. The refrigerant leakage detection device 207 according to the present embodiment is used as a device for detecting refrigerant leakage in the refrigerant circuit of the air conditioner. However, as in the second embodiment, the amount of change in capacitance due to the adsorption of refrigeration oil is compared. It is an effective device when it is small. In addition, since the structure of the air conditioning apparatus in which the refrigerant | coolant leak detection apparatus 207 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. The configuration of the refrigerant leak detection device 207 that is a feature of the present embodiment will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 10 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 207 according to the present embodiment. 10 includes a first sensor 271, a second sensor 272, a first oscillation circuit 273, a second oscillation circuit 274, a mixing circuit 275, a limiter circuit 276 (corresponding to an extraction unit), a counter circuit 277, A calculation unit 278 and a detection unit 279 are provided.

  The first sensor 271, the second sensor 272, and the detection unit 279 have the same configuration as the first sensor 71, the second sensor 72, and the detection unit 74 that are given the same names in the first embodiment. Therefore, detailed description is omitted. Below, the 1st and 2nd oscillation circuits 273 and 274, the mixing circuit 275, the limiter circuit 276, the counter circuit 277, and the calculating part 278 are demonstrated.

[First oscillation circuit and second oscillation circuit]
The first oscillation circuit 273 is connected to the first sensor 271, and the second oscillation circuit 274 is connected to the second sensor 272. The first oscillation circuit 273 oscillates at a frequency corresponding to the capacitance Cx of the first sensor 271. The second oscillation circuit 274 oscillates at a frequency corresponding to the electrostatic capacitance Cn of the second sensor 272. Specifically, the first oscillation circuit 273 oscillates at a frequency corresponding to the capacitance Cx of the first sensor 271 that has changed due to the adsorption of the refrigerating machine oil and the capacitance change factor acting as shown in FIG. 1st oscillation signal OS1 is output. The second oscillation circuit 274 oscillates at a frequency corresponding to the capacitance Cn of the second sensor 272 that has been changed by the action of only the capacitance change factor, and outputs a second oscillation signal OS2 as shown in FIG. .

  As the first oscillation circuit 273 and the second oscillation circuit 274, for example, a CR oscillation circuit mainly composed of the capacitance and resistance of each sensor, or mainly a coil and the capacitance of each sensor. Examples include an LC anti-coupling oscillation circuit.

[Mixed circuit]
The mixing circuit 275 has two input terminals, and each input terminal is connected to the output terminal of the first oscillation circuit 273 and the output terminal of the second oscillation circuit 274, respectively. The mixing circuit 275 mixes the first oscillation signal OS1 output from the first oscillation circuit 273 and the second oscillation signal OS2 output from the second oscillation circuit 274, and generates a second signal Sg2 as shown in FIG. Generate. Specifically, the mixing circuit 275 adds the first oscillation signal OS1 and the second oscillation signal OS2, which are alternating current signals, to thereby calculate the difference between the frequency of the first oscillation signal OS1 and the frequency of the second oscillation signal OS2. A second signal Sg2 having a frequency is output. In the second signal Sg2 generated in this way, a beat corresponding to the difference between the output of the first sensor 271 and the output of the second sensor 272 is generated. Particularly, even if the second signal Sg2 is not slightly different between the frequency of the first oscillation signal OS1 and the frequency of the second oscillation signal OS2, a beat corresponding to the difference is generated. Become.

[Limiter circuit]
The input terminal of the limiter circuit 276 is connected to the output terminal of the mixing circuit 275. The limiter circuit 276 extracts a signal in which the value of the second signal Sg2 is greater than or equal to a threshold value from the second signal Sg2 generated by the mixing circuit 275. That is, the limiter circuit 276 filters the second signal Sg2, and generates a pulsed signal Sa that satisfies the condition of a threshold value or more (see FIG. 11). The pulse-like signal Sa becomes a number of pulse signals corresponding to the beat of the second signal Sg2.

  Here, the threshold value is determined in advance based on, for example, the capacitance or experiment that the first sensor 271 and the second sensor 272 originally have without depending on the capacitance change factor or the like.

[Counter circuit]
The input terminal of the counter circuit 277 is connected to the output terminal of the limiter circuit 276. The counter circuit 277 counts the number of signals (that is, the pulsed signal Sa) extracted by the limiter circuit 276. As a result, the number of pulsed signals Sa corresponding to the beat of the second signal Sg2 is counted, so that the beat frequency in the second signal Sg2 can be accurately grasped.

[Calculation section]
The arithmetic unit 278 is connected to the output terminal of the counter circuit 277. The computing unit 278 calculates a first difference between the output of the first sensor 271 and the output of the second sensor 272 based on the count result by the counter circuit 277. Specifically, the calculation unit 278 grasps the beat frequency in the second signal Sg2 based on the count result, and calculates the first difference from this frequency. Next, the calculation unit 278 obtains a change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference, and outputs it to the detection unit 279.

  In addition, the calculating part 278 may be comprised with the circuit for a calculation similarly to the calculating part 73 which concerns on 1st Embodiment, or may be comprised with the microcomputer which consists of memory and CPU. In this embodiment, the case where the calculating part 278 is comprised with the microcomputer is taken as an example.

(2) Effect According to the refrigerant leakage detection device 207 according to the present embodiment, the signals OS1 and OS2 oscillated at frequencies corresponding to the electrostatic capacitances Cx and Cn of the sensors 271 and 272 are mixed, whereby the second signal Sg2 Of the second signal Sg2 is extracted as a pulsed signal Sa. Then, by counting the number of pulses of the pulsed signal Sa, the number of the signals Sa is integrated, so that the frequency of the pulsed signal Sa can be accurately grasped. Accordingly, only the change in the electrostatic capacity due to the adsorption of the refrigerating machine oil can be extracted with high accuracy from the first difference obtained based on the count result of the counter circuit 277, so that the refrigerant leakage can be detected more accurately. it can.

(3) Modification (a)
The counter circuit 277 according to the refrigerant leakage detection device 207 may be configured to generate a carry when the count result reaches a desired value. Even with such a configuration, the calculation unit 278 can determine the first difference, as in the above description.

(B)
In the refrigerant leakage detection device 207, a low-pass filter may be provided instead of the limiter circuit 276. The low-pass filter extracts only frequency components lower than the beat frequency. In this case, the counter circuit 277 counts the number of signals extracted by the low-pass filter, and the calculation unit 278 calculates the first difference based on the count result by the counter circuit 277.

<Fourth embodiment>
Next, the refrigerant leakage detection device 307 according to the fourth embodiment of the present invention will be described. The refrigerant leakage detection device 307 according to the present embodiment is used as a device for detecting refrigerant leakage in the refrigerant circuit of the air conditioner, as in the first embodiment. In addition, since the structure of the air conditioning apparatus by which the refrigerant | coolant leakage detection apparatus 307 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. The configuration of the refrigerant leakage detection device 307, which is a feature of this embodiment, will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 12 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 307 according to the present embodiment. 12 includes a first sensor 371, a second sensor 372, a third oscillation circuit 373, a fourth oscillation circuit 374, an up / down count circuit 375, a reset circuit 376, a calculation unit 377, and a detection unit 378. Prepare. The first sensor 371, the second sensor 372, and the detection unit 378 have the same configuration as the first sensor 71, the second sensor 72, and the detection unit 74 that are given the same names in the first embodiment. The third oscillation circuit 373 and the fourth oscillation circuit 374 have the same configuration as the first oscillation circuit 273 and the second oscillation circuit 274 according to FIG. 10 shown with the same names in the third embodiment. Therefore, detailed description of the first and second sensors 371, 372, the third and fourth oscillation circuits 373, 374, and the detection unit 378 is omitted, and an up / down count circuit 375, a reset circuit 376, and an arithmetic unit are hereinafter described. 377 will be described.

[Up / down count circuit]
The up / down count circuit 375 has two input terminals, and each input terminal is connected to the output terminal of the third oscillation circuit 373 and the output terminal of the fourth oscillation circuit 374. The up / down count circuit 375 up-counts the output of the third oscillation circuit 373 that oscillates at a frequency corresponding to the capacitance Cx of the first sensor 371 (hereinafter referred to as the third oscillation signal OS3), and the second sensor The output of the fourth oscillation circuit 374 that oscillates at a frequency corresponding to the electrostatic capacity Cn of 372 (hereinafter referred to as the fourth oscillation signal OS4) is down-counted. The up / down count circuit 375 performs the above operation at predetermined intervals. Accordingly, the frequency of the third oscillation signal OS3 based on the first sensor 371 on which the refrigeration oil adsorption and the capacitance change factor act, and the fourth oscillation signal on the second sensor 372 on which only the capacitance change factor acts. The number of pulses corresponding to the difference from the frequency of OS4 is counted.

[Reset circuit]
The output terminal of the reset circuit 376 is connected to the reset terminal of the up / down count circuit 375. The reset circuit 376 resets the count value by the up / down count circuit 375 every predetermined cycle. The predetermined cycle is determined in advance based on, for example, the capacitance or experiment that the first sensor 371 and the second sensor 372 originally have without depending on the capacitance change factor or the like.

  The up / down count circuit 375 reset by the reset circuit 376 initializes the count value that has been counted so far, and counts up and down from the beginning.

[Calculation section]
The calculation unit 377 is connected to the output terminal of the up / down count circuit 375. Since the number of pulses counted until the up / down count circuit 375 is reset corresponds to the difference between both frequencies of the third and fourth oscillation signals OS3 and OS4, the arithmetic unit 377 is operated by the up / down count circuit 375. Based on the count value, a first difference between the output of the first sensor 371 and the output of the second sensor 372 is determined. Next, the calculation unit 377 obtains a change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference, and outputs the obtained result to the detection unit 378.

  In addition, the calculating part 377 may be comprised by the circuit for a calculation similarly to the calculating part 73 which concerns on 1st Embodiment, or may be comprised by the microcomputer which consists of memory and CPU. In the present embodiment, a case where the calculation unit 377 is configured by a microcomputer is taken as an example.

(2) Effect (A)
According to the refrigerant leakage detection device 307 according to the present embodiment, the up / down count circuit 375 up-counts the signal oscillated according to the capacitance Cx of the first sensor 371 and the capacitance Cn of the second sensor 372. The signal oscillated according to is counted down. Since the count value by the up / down count circuit 375 is the number of pulses corresponding to the difference between the frequency according to the capacitance Cx of the first sensor 371 and the frequency according to the capacitance Cn of the second sensor 372, The unit 377 can obtain the first difference based on the count value. Further, since the calculation unit 377 can obtain only the capacitance change due to the adsorption of the refrigerating machine oil by obtaining the capacitance change based on the first difference, the detection unit 378 Refrigerant leakage can be detected more accurately.

(B)
Further, according to the refrigerant leakage detection device 307, the count value by the up / down count circuit 375 is reset by the reset circuit 376 at predetermined intervals. Therefore, the calculation unit 377 can obtain the first difference between the output of the first sensor 371 and the output of the second sensor 372 based on the count value before being reset.

(3) Modification The up / down count circuit 375 according to the refrigerant leakage detection device 307 may be configured such that a carry occurs when the count result reaches a desired value. Even with such a configuration, the calculation unit 377 can determine the first difference as in the above description.

<Fifth Embodiment>
Next, a refrigerant leakage detection device 407 according to a fifth embodiment of the present invention will be described. The refrigerant leakage detection device 407 according to the present embodiment is used as a device for detecting refrigerant leakage in the refrigerant circuit of the air conditioner, as in the first embodiment. In addition, since the structure of the air conditioning apparatus by which the refrigerant | coolant leakage detection apparatus 407 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. The configuration of the refrigerant leakage detection device 407 that is a feature of the present embodiment will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 13 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 407 according to the present embodiment. 13 includes a first sensor 471, a second sensor 472, a first reset circuit 473, a second reset circuit 474, an oscillation circuit 475, a first count circuit 476, a second count circuit 477, A latch circuit 478, a second latch circuit 479, a difference circuit 480 (corresponding to a difference calculation unit), a calculation unit 481, and a detection unit 482 are provided. The first sensor 471, the second sensor 472, and the detection unit 482 have the same configuration as the first sensor 71, the second sensor 72, and the detection unit 74 that are given the same names in the first embodiment. Therefore, detailed description is omitted. Hereinafter, the first reset circuit 473, the second reset circuit 474, the oscillation circuit 475, the first count circuit 476, the second count circuit 477, the first latch circuit 478, the second latch circuit 479, the difference circuit 480, and the calculation unit 481 Will be described.

[First reset circuit and second reset circuit]
The first reset circuit 473 is connected to the first sensor 471, and the second reset circuit 474 is connected to the second sensor 472. The output terminal of the first reset circuit 473 is connected to each reset terminal of the first count circuit 476 and the first latch circuit 478. The output terminal of the second reset circuit 474 is connected to each reset terminal of the second count circuit 477 and the second latch circuit 479.

  The first reset circuit 473 outputs a first reset signal Rx based on the time constant determined by the capacitance Cx of the first sensor 471 to the first count circuit 476 and the first latch circuit 478. The second reset circuit 474 outputs a second reset signal Rn based on the time constant determined by the capacitance Cn of the second sensor 472 to the second count circuit 477 and the second latch circuit 479. More specifically, the first reset circuit 473 is for resetting the first count circuit 476 and the first latch circuit 478 in accordance with the capacitance Cx changed due to the adsorption of the refrigerating machine oil and the capacitance change factor. The first reset signal Rx is output. The second reset circuit 474 outputs a second reset signal Rn for resetting the second count circuit 477 and the second latch circuit 479 in accordance with the capacitance Cn changed only by the capacitance change factor. That is, the reset circuits 473 and 474 can determine the time for the latch circuits 478 and 479 to hold the input signals based on the capacitances Cx and Cn of the sensors 471 and 472, respectively. The reset circuits 473 and 474 can determine the time for the count circuits 476 and 477 to reset the count value based on the electrostatic capacitances Cx and Cn of the sensors 471 and 472, respectively.

  Note that the reset circuits 473 and 474 according to the present embodiment output the reset signals Rx and Rn in synchronization with the reference clock. That is, each reset circuit 473, 474 obtains a time constant based on the electrostatic capacitances Cx, Cn of the respective sensors 471, 472 at each predetermined timing, and outputs reset signals Rx, Rn based on the obtained time constant. Output.

[Oscillation circuit]
The output terminal of the oscillation circuit 475 is connected to the input terminals of the first count circuit 476 and the second count circuit 477, and outputs an oscillation signal OS5 (corresponding to a pulse signal) to each count circuit 476,477. As shown in FIG. 14, the oscillation signal OS5 is a pulse signal having a predetermined frequency. The predetermined frequency of the oscillation signal OS5 is determined in advance by experiments or the like regardless of the capacitance Cx of the first sensor 471 and the capacitance Cn of the second sensor 472.

[First count circuit and second count circuit]
The first count circuit 476 counts the number of pulses of the oscillation signal OS5 and stops counting the oscillation signal OS5 based on the first reset signal Rx. The second count circuit 477 counts the number of pulses of the oscillation signal OS5 and stops counting the oscillation signal OS5 based on the second reset signal Rn. Specifically, the first count circuit 476 performs the count operation of the oscillation signal OS5 while the first reset signal Rx is “L” indicating reset-off (period Toff1 in FIG. 14). When the first reset signal Rx becomes “H” indicating reset on, the count of the oscillation signal OS5 is stopped. Similarly to the first count circuit 476, the second count circuit 477 counts the oscillation signal OS5 if the second reset signal Rn is “L”, and if the second reset signal Rn is “H”. The count of the oscillation signal OS5 is stopped.

  As shown in FIG. 14, the length of the period Toff1 during which the first reset signal Rx outputs the reset-off “L” is the length of the second reset signal Rn that outputs the reset-off “L”. Different from the length of the period Toff2. This is because the reset signals Rx and Rn are determined based on the capacitances Cx and Cn of the sensors 471 and 472, as already described in [First reset circuit and second reset circuit]. . That is, since the time constant used when the reset signals Rx and Rn are determined is proportional to the capacitances Cx and Cn of the sensors 471 and 472, the first reset signal Rx outputs the reset off “L”. The difference DifA between the length of the current period Toff1 and the length of the period Toff2 during which the second reset signal Rn outputs reset-off “L” corresponds to the difference between the capacitances Cx and Cn of the sensors 471 and 472 I can say that. In particular, in FIG. 14, the period Toff1 in which the first reset signal Rx outputs reset-off “L” is longer than the period Toff2 in which the second reset signal Rn outputs reset-off “L”. This is because the capacitance Cx of the first sensor 471 changes depending on the refrigerating machine oil and the capacitance change factor, whereas the capacitance Cn of the second sensor 472 changes based only on the capacitance change factor. It is. That is, the period Toff1 of the first reset signal Rx is longer than the period Toff2 of the second reset signal Rn by the amount of change due to the adsorption of the refrigerating machine oil.

[First latch circuit and second latch circuit]
The first latch circuit 478 has its input terminal connected to the output terminal of the first count circuit 476 and holds the count value by the first count circuit 476. The second latch circuit 479 has its input terminal connected to the output terminal of the second count circuit 477 and holds the count value of the second count circuit 477.

  As described above, the first reset signal Rx is input to the first latch circuit 478, and the second reset signal Rn is input to the second latch circuit 479. Therefore, the latch circuits 478 and 479 continue to hold the count values while the reset signals Rx and Rn are reset off “L”. When the reset signals Rx and Rn are reset on “H”, the latch circuits 478 and 479 reset the count values held so far.

[Difference circuit]
The difference circuit 480 has two input terminals, and each input terminal is connected to the output terminal of the first latch circuit 478 and the output terminal of the second latch circuit 479. The difference circuit 480 obtains a second difference of the count number counted until each of the first count circuit 476 and the second count circuit 477 stops counting the oscillation signal OS5. Here, since the count values of the count circuits 476 and 477 are related to the lengths of the periods Toff1 and Toff2 of the reset-off “L” of the reset signals Rx and Rn, the first count obtained by the difference circuit 480 is obtained. The second difference between the count value of the circuit 476 and the count value of the second count circuit 477 corresponds to the difference DifA between the lengths of the periods Toff1 and Toff2, that is, the change in capacitance due to adsorption of the refrigerator oil. It can be said.

[Calculation section]
The calculation unit 481 is connected to the output terminal of the difference circuit 480. The computing unit 481 obtains a first difference between the output of the first sensor 471 and the output of the second sensor 472 based on the second difference obtained by the difference circuit 480. Then, the calculation unit 481 obtains a change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference, and outputs the obtained result to the detection unit 482.

  In addition, the calculating part 481 may be comprised with the circuit for a calculation similarly to the calculating part 73 which concerns on 1st Embodiment, or may be comprised with the microcomputer which consists of memory and CPU. In this embodiment, the case where the calculating part 481 is comprised with the microcomputer is taken as an example.

(2) Effects According to the refrigerant leakage detection device 407 according to the present embodiment, the first count circuit 476 counts the oscillation signal OS5 until the reset is instructed by the first reset signal Rx, and the second count circuit 477 The oscillation signal OS5 is counted until the reset is instructed by the second reset signal Rn. Here, the first reset signal Rx and the second reset signal Rn are respectively determined based on a signal based on the time constant determined from the capacitance Cx of the first sensor 471 and the capacitance Cn of the second sensor 472. Since the signal is based on a constant, the timing at which the first count circuit 476 and the second count circuit 477 stop counting is different. That is, the difference in the number of counts by the count circuits 476 and 477 corresponds to the difference between the capacitances Cx and Cn of the sensors 471 and 472. Therefore, the refrigerant leakage detection device 407 can obtain the first difference based on the second difference between the count numbers. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy, and refrigerant leakage can be detected more accurately.

<Sixth Embodiment>
Next, a refrigerant leakage detection device 507 according to a sixth embodiment of the present invention will be described. The refrigerant leakage detection device 507 according to the present embodiment is used as a device for detecting refrigerant leakage in the refrigerant circuit of the air conditioner, as in the first embodiment. In addition, since the structure of the air conditioning apparatus by which the refrigerant | coolant leak detection apparatus 507 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. The configuration of the refrigerant leakage detection device 507, which is a feature of this embodiment, will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 15 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 507 according to the present embodiment. 15 includes a first sensor 571, a second sensor 572, a third reset circuit 573, a first timer circuit 574, a second timer circuit 575, an EOR circuit 576, an oscillation circuit 577, and a fourth reset circuit. 578, a count circuit 579 (EOR circuit 576 and count circuit 579 correspond to a time calculation unit), a calculation unit 580, and a detection unit 581. In addition, about the 1st sensor 571, the 2nd sensor 572, and the detection part 581, it has the same structure as the 1st sensor 71, the 2nd sensor 72, and the detection part 74 which attached | subjected and showed the same name in 1st Embodiment. Therefore, detailed description is omitted. Below, the 3rd reset circuit 573, the 1st timer circuit 574, the 2nd timer circuit 575, the EOR circuit 576, the oscillation circuit 577, the 4th reset circuit 578, the count circuit 579, and the calculating part 580 are demonstrated.

[Third reset circuit]
The output terminal of the third reset circuit 573 is connected to each reset terminal of the first timer circuit 574 and the second timer circuit 575. The third reset circuit 573 generates a signal for resetting the timer circuits 574 and 575 and outputs the signal to the timer circuits 574 and 575.

[First timer circuit and second timer circuit]
The input terminal of the first timer circuit 574 is connected to the first sensor 571, and the input terminal of the second timer circuit 575 is connected to the second sensor 572.

  As shown in FIG. 16, the first timer circuit 574 first determines the time Tx according to the capacitance Cx of the first sensor 571 that has changed due to the adsorption of the refrigerating machine oil and the capacitance change factor, After being reset once by the reset circuit 573, time measurement is started. Then, when the measurement time has passed the time Tx, the first timer circuit 574 outputs a first time elapsed signal St1 indicating that fact. The second timer circuit 575 first determines the time Tn according to the capacitance Cn of the second sensor 572 that has changed only due to the capacitance change factor, and after being reset by the third reset circuit 573, Start measuring. Then, when the time Tn has elapsed, the second timer circuit 575 outputs a second time elapsed signal St2 indicating that the time has elapsed.

  As shown in FIG. 16, the first time elapsed signal St1 according to the present embodiment is “L” when the time measured by the first timer circuit 574 has not elapsed time Tx, and when it has elapsed, It shall have a logic of “H”. Similarly, the second time elapsed signal St2 has a logic of “L” when the time measured by the second timer circuit 575 has not elapsed the time Tn, and “H” when it has elapsed. The time elapse signals St1 and St2 (both “H”) indicating that the times Tx and Tn have elapsed are continuously output until the timer circuits 574 and 575 are reset by the third reset circuit 573.

  In addition, as a method for determining the times Tx and Tn, the first method is determined by multiplying the capacitances Cx and Cn by a predetermined coefficient, and based on the capacitances Cx and Cn as in the fifth embodiment. Although the 2nd method etc. determined by a time constant are mentioned, in this embodiment, the case where it is the 1st method is taken as an example. As described above, when the times Tx and Tn are determined by the capacitances Cx and Cn, as shown in FIG. 16, the first time elapsed signal St1 “H” indicating that the time Tx has elapsed, and the time The timing at which the second time elapsed signal St2 “H” indicating that Tn has elapsed starts to be output in accordance with the values of the capacitances Cx and Cn. That is, the difference DifB between the timing at which the time Tx elapses and the first time elapsed signal St1 “H” starts to be output and the timing at which the time Tn elapses and the second time elapsed signal St2 “H” starts to be output is This corresponds to the difference between the capacitances Cx and Cn. In particular, the period Tx in which the first time elapsed signal St1 is “L” is longer than the period Tn in which the second time elapsed signal St2 is “L”. This is because the capacitance Cn of the second sensor 572 changes based only on the capacitance change factor, whereas the capacitance Cx of the first sensor 571 is not only due to the capacitance change factor but also due to refrigerating machine oil. Because it also changes. That is, the timing difference DifB at which the time elapsed signals St1 and St2 that are “H” start to be output corresponds to a change in capacitance due to adsorption of the refrigerating machine oil.

[EOR circuit]
The EOR circuit 576 has two input terminals, and the output terminals of the timer circuits 574 and 575 are connected to each input terminal. The EOR circuit 576 is a so-called exclusive OR circuit, and as shown in FIG. 16, the first time lapse signal St1 and the second time lapse signal output from the first and second timer circuits 574 and 575, respectively. When any of St2 is “H”, the enable signal En “H” is output. Specifically, the EOR circuit 576 detects the case where the time Tx based on the capacitance Cx has elapsed but the Tn based on the capacitance Cn has not elapsed.

  The EOR circuit 576 outputs the enable signal En “L” when both the first time elapsed signal St1 and the second time elapsed signal St2 are “L” or “H”.

[Oscillation circuit]
The output terminal of the oscillation circuit 577 is connected to the oscillation signal input terminal of the count circuit 579. The oscillation circuit 577 outputs the oscillation signal OS6 to the count circuit 579. As shown in FIG. 16, the oscillation signal OS6 is a pulse signal having a predetermined frequency. As with the oscillation signal OS5 according to the fifth embodiment, the predetermined frequency of the oscillation signal OS6 is determined in advance through experiments or the like regardless of the capacitance Cx of the first sensor 571 and the capacitance Cn of the second sensor 572. Is done.

[Fourth reset circuit]
The output terminal of the fourth reset circuit 578 is connected to the reset terminal of the count circuit 579. The fourth reset circuit 578 generates a signal for resetting the count circuit 579 and outputs the signal to the count circuit 579.

[Count circuit]
The output terminal of the EOR circuit 576 is connected to the input terminal of the count circuit 579 different from the oscillation signal input terminal. The count circuit 579 counts the number of pulses of the oscillation signal OS6 only during the period DifB where the enable signal En is “H”. Thereby, the number of pulses counted by the count circuit 579 becomes a value corresponding to the length of the period DifB.

  In addition, when a signal for resetting is input from the fourth reset circuit 578, the count circuit 579 resets the count value so far.

[Calculation section]
The arithmetic unit 580 is connected to the output terminal of the count circuit 579. The calculation unit 580 calculates the first difference between the output of the first sensor 571 and the output of the second sensor 572 based on the number of pulses counted by the count circuit 579. That is, the calculation unit 580 has a value in which the number of pulses counted by the count circuit 579 is a value corresponding to the length of the period DifB, and the length of the period DifB is the difference between the capacitances Cx and Cn of the sensors 571 and 572. Therefore, the first difference can be obtained. Then, the calculation unit 580 obtains a change in capacitance due to the adsorption of the refrigerating machine oil based on the first difference, and outputs the obtained result to the detection unit 581.

  In addition, the calculating part 580 may be comprised by the circuit for a calculation similarly to the calculating part 73 which concerns on 1st Embodiment, or may be comprised by the microcomputer which consists of memory and CPU. In this embodiment, the case where the calculating part 580 is comprised with the microcomputer is taken as an example.

(2) Effect If the capacitances Cx and Cn of the sensors 571 and 572 are different, the times Tx and Tn determined by the capacitances Cx and Cn of the sensors 571 and 572 are different. The timings at which the signal St1 “H” and the second time elapsed signal St2 “H” start to be output are also different. Therefore, the refrigerant leak detection device 507 according to the present embodiment has a length of the period DifB in which one of the first time elapsed signal St1 and the second time elapsed signal St2 is “H”, that is, the first time elapsed signal St1. The first difference is obtained based on the difference between the timing at which “H” starts to be output and the timing at which the second time elapsed signal St2 “H” starts to be output. That is, since the length of the period DifB corresponds to the change in capacitance due to the adsorption of the refrigerating machine oil, only the change in capacitance due to the adsorption of the refrigerating machine oil can be extracted with high accuracy, and the refrigerant leakage can be more accurately performed. Can be detected.

<Seventh embodiment>
Next, a refrigerant leakage detection device 607 according to a seventh embodiment of the present invention will be described. As in the first to sixth embodiments, the refrigerant leakage detection device 607 according to the present embodiment is used as a device for detecting refrigerant leakage in the refrigerant circuit of the air conditioner. In particular, the refrigerant leak detection device 607 according to the present embodiment is a device in which the up / down count circuit can obtain a more accurate count value in the refrigerant leak detection device 307 of the fourth embodiment. In addition, since the structure of the air conditioning apparatus by which the refrigerant | coolant leak detection apparatus 607 is mounted is the same as that of the air conditioning apparatus 1 demonstrated using FIG. 1 in 1st Embodiment, it demonstrates the structure of an air conditioning apparatus below. The configuration of the refrigerant leakage detection device 607, which is a feature of this embodiment, will be described.

(1) Configuration of Refrigerant Leak Detection Device FIG. 17 is a diagram illustrating a circuit configuration of the refrigerant leak detection device 607 according to the present embodiment. The refrigerant leakage detection device 607 of FIG. 17 is configured to include a selection circuit 675 instead of the reset circuit 376 in the refrigerant leakage detection device 307 according to the fourth embodiment. Specifically, the refrigerant leakage detection device 607 includes a first sensor 671, a second sensor 672, a third oscillation circuit 373, a fourth oscillation circuit 374, a selection circuit 675, an up / down count circuit 681, a calculation unit 682, and a detection unit 683. Is provided. In addition, the 1st sensor 671, the 2nd sensor 672, and the detection part 683 have the same structure as the 1st sensor 71, the 2nd sensor 72, and the detection part 74 which attached | subjected and showed the same name in 1st Embodiment. The third oscillation circuit 673 and the fourth oscillation circuit 674 have the same configuration as the first oscillation circuit 273 and the second oscillation circuit 274 according to FIG. 10 shown with the same names in the third embodiment. Furthermore, the up / down count circuit 681 and the calculation unit 682 have the same configuration as the up / down count circuit 375 and the calculation unit 377 according to FIG. Therefore, detailed descriptions of the first and second sensors 671, 672, the third and fourth oscillation circuits 673, 674, the up / down count circuit 681, the calculation unit 682, and the detection unit 683 are omitted, and the selection circuit is described below. 675 will be described.

  The selection circuit 675 selects either the output of the third oscillation circuit 673 (namely, the third oscillation signal OS3 ′) or the output of the fourth oscillation circuit 674 (namely, the fourth oscillation signal OS4 ′), and up-down This is a circuit for inputting to the count circuit 681. Specifically, the selection circuit 675 includes a control signal circuit 676, a counter circuit 677, a logic circuit 678 having output terminals for enable signals SX and SN, and two NAND circuits 679 and 680.

  The control signal circuit 676 generates a clock signal having a predetermined duty and frequency and outputs it to the counter circuit 677. Note that the duty and frequency of the signal output from the control signal circuit 676 are determined in advance by the capacitance etc. that the first sensor 671 and the second sensor 672 do not depend on the capacitance change factor. ing. The signal output from the control signal circuit 676 is counted by the counter circuit 677 and then sent to the logic circuit 678. The logic circuit 678 generates two enable signals SX and SN as shown in FIG. 18 from the count result of the counter circuit 677. Here, the enable signals SX and SN are both signals having logic of “H” or “L”, but the enable signal SX and the enable signal SN have exclusive logic. For example, when the enable signal SX has a logic “H”, the enable signal SN has a logic “L”. The enable signal SX is input to one input terminal of the two input terminals of the NAND circuit 679, and the enable signal SN is input to one input terminal of the two input terminals of the NAND circuit 680. Entered. The third oscillation signal OS3 'is input to the other input terminal of the NAND circuit 679, and the fourth oscillation signal OS4' is input to the other input terminal of the NAND circuit 680.

  The NAND circuit 679 described above outputs the third oscillation signal OS3 ′ when the logic of the enable signal SX is “H”, and the NAND circuit 680 outputs the third oscillation signal OS3 ′ when the logic of the enable signal SN is “H”. The fourth oscillation signal OS4 ′ is output. Here, as described above, both the enable signal SX and the enable signal SN do not have the logic “H”, but alternately have the logic “H”. Either the third oscillation signal OS3 ′ or the fourth oscillation signal OS4 ′ is input (FIG. 18). That is, the third oscillation signal OS3 ′ and the fourth oscillation signal OS4 ′ are not input to the up / down count circuit 681 at the same time, but the third oscillation signal OS3 ′ and the fourth oscillation signal selected by the selection circuit 675. One of the OSs 4 'is input. Accordingly, the up / down count circuit 681 can reliably perform the operation of up-counting the third oscillation signal OS3 'and down-counting the fourth oscillation signal OS4'. Accordingly, an accurate count value is output from the up / down count circuit 681 to the calculation unit 682, and the calculation unit 682 outputs the output of the first sensor 671 and the output of the second sensor 672 based on the count value. The first difference and the change in capacitance due to the adsorption of refrigerating machine oil based on the first difference can be reliably obtained. The capacitance change obtained by the calculation unit 682 in this way is output to the detection unit 683.

  As in the third embodiment, the detection unit 683 determines whether the refrigerant is leaking based on the change in capacitance, and outputs the determination result and the amount of refrigerating machine oil. Furthermore, the detection unit 683 may output the capacitance change itself.

  Furthermore, the logic circuit 678 according to the present embodiment has an output terminal of the reset signal Clear in addition to the output terminals of the enable signals SX and SN (the logic circuit 678 has an output terminal of the reset signal Clear. The part that is equivalent to the reset part). The reset signal Clear plays a role of resetting the count value by the up / down count circuit 681 every predetermined period. Here, like the clock signal output from the control signal circuit 676, the predetermined cycle is based on the electrostatic capacity originally possessed by the first sensor 671 and the second sensor 672 without depending on the electrostatic capacity change factor. Are determined in advance. The up / down count circuit 681 reset by the reset signal Clear initializes the count value that has been counted so far, and counts up and down from the beginning.

(2) Effect (A)
According to the refrigerant leakage detection device 607 according to the present embodiment, either the third oscillation signal OS3 ′ or the fourth oscillation signal OS4 ′ is input to the up / down count circuit 681. That is, the third oscillation signal OS3 ′ and the fourth oscillation signal OS4 ′ are not simultaneously input to the up / down count circuit 681. Therefore, the up / down count circuit 681 can reliably perform the operation of up-counting the third oscillation signal OS3 ′ and down-counting the fourth oscillation signal OS4 ′, and an accurate count value for obtaining the first difference. You will be able to get

(B)
Further, according to the refrigerant leakage detection device 607, the count value by the up / down count circuit 681 is reset at predetermined intervals by the reset signal Clear output from the logic circuit 678. Therefore, the calculation unit 682 can obtain the first difference between the output of the first sensor 671 and the output of the second sensor 672 based on the count value before being reset.

<Other embodiments>
(A)
In the first to seventh embodiments, the case where the calculation unit and the detection unit exist separately has been described. However, the calculation unit and the detection unit are not separate, and may be provided as one circuit or a microcomputer. Hereinafter, in particular, in the third to seventh embodiments, an example in which the calculation unit and the detection unit are integrally provided as a determination circuit will be briefly described.

(A-1)
In the third embodiment, instead of the calculation unit 278 and the detection unit 279 of FIG. 10 being provided separately, a determination circuit in which the calculation unit 278 and the detection unit 279 are integrated may be provided. In this case, the determination circuit compares the count value of the counter circuit 277 with a threshold value, and determines whether or not the refrigerant has leaked according to the comparison result. Even in such a configuration, the count value corresponds to the difference between the capacitance Cx of the first sensor 271 and the capacitance Cn of the second sensor 272, that is, the amount of change in capacitance due to adsorption of refrigeration oil. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy.

(A-2)
In the fourth embodiment, instead of the calculation unit 377 and the detection unit 378 of FIG. 12 being provided separately, a determination circuit in which the calculation unit 377 and the detection unit 378 are integrated may be provided. In this case, the determination circuit compares the count value by the up / down count circuit 375 with a threshold value, and determines whether or not the refrigerant has leaked according to the comparison result. Even in such a configuration, the count value corresponds to the difference between the capacitance Cx of the first sensor 371 and the capacitance Cn of the second sensor 372, that is, the amount of change in capacitance due to adsorption of refrigerating machine oil. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy.

  Similarly, in the seventh embodiment, instead of the calculation unit 682 and the detection unit 683 of FIG. 17 being provided separately, a determination circuit in which the calculation unit 682 and the detection unit 683 are integrated may be provided. good.

(A-3)
In the fifth embodiment, instead of the calculation unit 481 and the detection unit 482 of FIG. 13 being provided separately, a determination circuit in which the calculation unit 481 and the detection unit 482 are integrated may be provided. In this case, the determination circuit compares the second difference obtained by the difference circuit 480 with a threshold value, and determines whether or not the refrigerant has leaked according to the comparison result. Even in such a configuration, the second difference is equivalent to the difference between the capacitance Cx of the first sensor 471 and the capacitance Cn of the second sensor 472, that is, the amount of change in capacitance due to adsorption of refrigeration oil. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy.

(A-4)
In the sixth embodiment, instead of the calculation unit 580 and the detection unit 581 of FIG. 15 being provided separately, a determination circuit in which the calculation unit 580 and the detection unit 581 are integrated may be provided. In this case, the determination circuit compares the number of pulses counted by the count circuit 579 with a threshold value, and determines whether or not the refrigerant has leaked according to the comparison result. Even in such a configuration, the number of pulses corresponds to the difference between the capacitance Cx of the first sensor 571 and the capacitance Cn of the second sensor 572, that is, the amount of change in capacitance due to adsorption of refrigeration oil. Therefore, only the change in capacitance due to the adsorption of the refrigerating machine oil can be taken out with high accuracy.

(B)
In the refrigerant leakage detection devices according to the first to seventh embodiments, the case where two types of sensors whose capacitance changes are provided has been described. However, the number of sensors is not limited to this, and two or more sensors may be provided.

  The refrigerant leakage detection device according to the present invention has an effect that it is possible to accurately know whether or not refrigerant leakage has occurred even when the sensor is affected by humidity. Therefore, the refrigerant leakage detection device can be applied as a device for detecting leakage of the refrigerant flowing on the refrigerant circuit in a refrigeration apparatus such as an air conditioner.

The schematic block diagram of the air conditioning apparatus 1 which concerns on 1st Embodiment. The figure which shows schematically the structure of the refrigerant | coolant leak detection apparatus 7 which concerns on 1st Embodiment. The figure which shows the 1st sensor 71 and the 2nd sensor 72 which are arrange | positioned in refrigerant | coolant piping vicinity. The perspective view of the 1st sensor 71. FIG. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 7 which concerns on 1st Embodiment. The figure which shows an example of the electrostatic capacitance Cx of the 1st sensor 71 and the electrostatic capacitance Cn of the 2nd sensor 72 which change with time. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 107 which concerns on 2nd Embodiment. The figure which shows 1st signal Sg1 produced | generated when the output of each voltage conversion circuit 173,174 is chopped by the chopping circuit 175. FIG. FIG. 9 is a diagram illustrating the frequency distribution of the first signal Sg1 in FIG. 8 with the horizontal axis representing frequency and the vertical axis representing amplitude. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 207 which concerns on 3rd Embodiment. The capacitance Cx of the first sensor 271 that changes over time, the capacitance Cn of the second sensor 272, the second signal Sg2 that is the output of the mixing circuit 275, and a pulsed signal extracted from the second signal Sg2. The figure showing Sa. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 307 which concerns on 4th Embodiment. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 407 which concerns on 5th Embodiment. 4 is a timing chart of an oscillation signal OS5, a first reset signal Rx, and a second reset signal Rn. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 507 which concerns on 6th Embodiment. The timing chart of 1st time passage signal St1, 2nd time passage signal St2, enable signal En, and oscillation signal OS6. The figure which shows the circuit structure of the refrigerant | coolant leak detection apparatus 607 which concerns on 7th Embodiment. 6 is a timing chart showing signals input to the enable signals SX and SN and the up / down count circuit 681. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Refrigerant circuit 3 Use unit 4 Heat source unit 5,6 Refrigerant communication piping 7,107,207,307,407,507,607 Refrigerant leak detection apparatus 71,171,271,371,471,571,671 1 sensor 71a, 71b electrode 72, 172, 272, 372, 472, 572, 672 second sensor 73, 177, 278, 377, 481, 580, 682 arithmetic unit 74, 178, 279, 378, 482, 581, 683 Detection unit 175 Chopping circuit 176 Noise removal circuit 273 First oscillation circuit 274 Second oscillation circuit 275 Mixer circuit 276 Limiter circuit 277 Counter circuit 373, 673 Third oscillation circuit 374, 674 Fourth oscillation circuit 375, 681 Up / down count circuit 376 Reset circuit 473 First reset times 474 second reset circuit 476 first counting circuit 477 second counting circuit 480 differential circuit 574 first timer circuit 575 the second timer circuit 576 EOR circuit 579 count circuit 675 selecting circuit 678 logic 679,680 NAND circuit

Claims (11)

The first sensors (71, 171, 271, 371) in which the capacitance (Cx) changes due to the action of adsorption of the refrigeration oil in the refrigeration system (1) and a predetermined capacitance change factor other than the refrigeration oil. 471,571,671),
A second sensor (72, 172, 272, 372, 472, 572, 672) in which the capacitance (Cn) is changed by the action of the predetermined capacitance change factor without the adsorption of the refrigerating machine oil; ,
Based on the first difference between the output of the first sensor (71,171,271,371,471,571,671) and the output of the second sensor (72,172,272,372,472,572,672). A calculation unit (73, 177, 278, 377, 481, 580, 682) for calculating a change in capacitance due to the adsorption of the refrigerating machine oil,
Detection units (74, 178) for detecting refrigerant leakage in the refrigeration apparatus (1) based on the capacitance change calculated by the calculation units (73, 177, 278, 377, 481, 580, 682). , 279, 378, 482, 581, 683),
A refrigerant leak detection device (7, 107, 207, 307, 407, 507, 607). The first sensor (71) and the second sensor (72) are connected in a bridge shape,
The refrigerant leak detection device (7) according to claim 1. A chopping unit (175) for chopping the output of the first sensor (171) and the output of the second sensor (172) at a predetermined frequency (fc) to generate a first signal (Sg1);
A noise removing unit (176) for removing noise from the first signal (Sg1) generated by the chopping unit (175);
Further comprising
The computing unit (177) obtains the first difference based on the first signal after noise is removed by the noise removing unit (176).
The refrigerant leakage detection device (107) according to claim 1. The predetermined frequency (fc) is a frequency different from the frequency of the noise of the first signal (Sg1).
The refrigerant leak detection device (107) according to claim 3. A first oscillating unit (273) that oscillates at a frequency corresponding to a capacitance (Cx) of the first sensor (271);
A second oscillating unit (274) that oscillates at a frequency corresponding to the capacitance (Cn) of the second sensor (272);
A mixing unit (275) for mixing the output (OS1) of the first oscillation unit (273) and the output (OS2) of the second oscillation unit (274) to generate a second signal (Sg2);
An extraction unit (276) for extracting a signal (Sa) having a value of the second signal (Sg2) equal to or greater than a threshold value from the second signal (Sg2) generated by the mixing unit (275);
A counting unit (277) that counts the extraction results by the extraction unit;
Further comprising
The calculation unit (278) obtains the first difference based on a count result by the count unit (277).
The refrigerant leakage detection device (207) according to claim 1. A third oscillation unit (373, 673) that oscillates at a frequency corresponding to the capacitance (Cx) of the first sensor (371, 671);
A fourth oscillation unit (374, 674) that oscillates at a frequency corresponding to the capacitance (Cn) of the second sensor (372, 672);
An up / down count unit that counts up the output (OS4, OS4 ′) of the fourth oscillation unit (374, 674) while counting up the output (OS3, OS3 ′) of the third oscillation unit (373, 673) ( 375, 681),
Further comprising
The calculation unit (377, 682) obtains the first difference based on the count value by the up / down count unit (375, 681).
The refrigerant leakage detection device (307, 607) according to claim 1. A selection unit (675) for selecting one of the output (OS3 ′) of the third oscillation unit (673) and the output (OS4 ′) of the fourth oscillation unit (674);
Further comprising
The up / down counting unit (681) includes an output (OS3 ′) of the third oscillation unit (673) selected by the selection unit (675) and an output (OS4 ′) of the fourth oscillation unit (674). Is entered,
The refrigerant leakage detection device (607) according to claim 6. A reset unit (376, 678) for resetting the count value by the up / down count unit (375, 681) at predetermined intervals;
Further comprising
The refrigerant | coolant leak detection apparatus (307,607) of Claim 6 or 7. A first reset unit (473) for outputting a first reset signal (Rx) based on a time constant determined by a capacitance (Cx) of the first sensor (471);
A second reset unit (474) for outputting a second reset signal (Rn) based on a time constant determined by the capacitance (Cn) of the second sensor (472);
A first count unit (476) that counts a pulse signal (OS5) having a predetermined frequency and stops counting the pulse signal (OS5) based on the first reset signal (Rx);
A second counting unit (477) that counts the pulse signal (OS5) and stops counting the pulse signal (OS5) based on the second reset signal (Rn);
A difference calculation unit (480) for obtaining a second difference of the counted number until each of the first count unit (476) and the second count unit (477) stops counting the pulse signal (OS5). When,
Further comprising
The calculation unit (481) obtains a first difference based on the second difference.
The refrigerant leakage detection device (407) according to claim 1. After a time (Tx) determined according to the capacitance (Cx) of the first sensor (571) has elapsed, a first timer unit (574) that outputs a first time lapse signal (St1) indicating that fact. When,
After a time (Tn) determined according to the capacitance (Cn) of the second sensor (572) has elapsed, a second timer unit (575) that outputs a second time lapse signal (St2) indicating that fact. When,
Time (DifB) during which any one of the first time lapse signal (St1) and the second time lapse signal (St2) is output from the first timer unit (574) or the second timer unit (575) An interval calculation unit (576, 579) for calculating the length of
Further comprising
The calculation unit (580) obtains the first difference based on the length of time calculated by the interval calculation unit (576, 579).
The refrigerant leak detection device (507) according to claim 1. A refrigerant circuit (2);
The refrigerant leakage detection device (7, 107, 207, 307, 407, 507, 607) according to any one of claims 1 to 10, which is arranged in the refrigerant circuit (2) or in the vicinity of the refrigerant leakage detection part. )When,
A refrigeration apparatus (1).

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