JP2007127326A - Engine drive type heat pump comprising refrigerant filling circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a wet operation in a refrigerant sudden change operation of an engine drive type heat pump, and to improve reliability in filling an appropriate amount of refrigerant. <P>SOLUTION: In this engine drive type heat pump 1 having a compressor 10 by driving of an engine, and a waste heat recovering unit 15 for evaporating a refrigerant by waste heat of the engine, a refrigerant filling circuit 69 having a refrigerant filling solenoid valve 31 and a charge valve 42 is joined with an upstream-side path of the waste heat recovering unit 15, and a refrigerant relief circuit 68 is branched to a discharge path of the compressor 10 from a path connecting the refrigerant filling solenoid valve 31 and the charge valve 42 of the refrigerant filling circuit 69. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a refrigerant charging technique for an engine-driven heat pump.

Generally, the required piping length of communication piping used to connect an outdoor unit and an indoor unit in installation work of an air conditioner such as an engine-driven heat pump varies depending on piping conditions at the installation site. Therefore, when installing the air conditioner on site, communication pipes having an appropriate pipe length are selected and used in consideration of the installation conditions of the outdoor unit and the indoor unit.
On the other hand, in the process of factory production of the air conditioner, a method is adopted in which the outdoor unit is filled with a predetermined amount of refrigerant in advance and the amount of refrigerant that is deficient is added according to the length of the connecting pipe at the time of local installation. It was.

Patent Document 1 discloses a refrigeration apparatus that can be filled with an optimal amount of refrigerant as a refrigerant filling end means. This refrigeration apparatus has a configuration in which a predetermined height position inside the receiver and the suction path are connected by a bypass path, and these are provided in this order in the bypass circuit in the order of an electromagnetic valve, a capillary, and a temperature sensor. In this refrigeration system, when the liquid level of the liquid refrigerant exceeds the predetermined height position inside the receiver while the additional refrigerant is being charged, the liquid refrigerant passes through the bypass path, and the temperature change is detected by the temperature sensor. Then, the completion of charging of the appropriate amount of refrigerant is detected.
Further, this refrigeration apparatus performs expansion valve control so that the degree of superheat of the suction pipe is not less than a predetermined position while controlling the outdoor fan that maintains the high pressure constant as a refrigerant charging operation control means, and thereby compresses the compressor. Protects driving.
JP 2002-350014 A

However, detection of the refrigerant temperature at one location after passing through the capillary may detect the temperature of the refrigerant suddenly entering the capillary and determine the end of filling, and the detection accuracy is low.
Further, normally, the additional refrigerant is charged from the gas side communication pipe (between the evaporator and the compressor) in a gas-liquid mixed state from the refrigerant cylinder. Therefore, in an electric air conditioner, if it does not go through an external heating means, it will become a compressor wet operation and will affect a compressor lifetime.
Further, although it is expected that the refrigerant cylinder will be empty during the additional refrigerant charging operation, there is usually no method other than replacing the cylinder when the operator notices it. For this reason, it is necessary to confirm the remaining amount of the refrigerant cylinder, and the man-hours for that amount are required.

  Therefore, the problem to be solved is to realize improvement in accuracy of determination of refrigerant filling end time, prevention of compressor wet operation, and detection of an empty state of a refrigerant cylinder in an engine-driven heat pump.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, in an engine-driven heat pump having a compressor driven by an engine and a waste heat recovery device that evaporates a refrigerant by waste heat of the engine, an on-off valve is provided in an upstream path of the waste heat recovery device. An engine-driven heat pump characterized by merging a refrigerant charging circuit having a refrigerant cylinder mounting portion.

  According to a second aspect of the present invention, a refrigerant escape circuit is branched to a discharge path of the compressor from a path connecting the on-off valve of the refrigerant charging circuit and a refrigerant cylinder mounting portion.

  According to a third aspect of the present invention, there is provided a suction temperature sensor that detects a refrigerant suction temperature in the suction path of the compressor, a suction pressure sensor that detects a refrigerant suction pressure in the suction path of the compressor, the refrigerant suction temperature, and the refrigerant suction. There is provided on-off valve control means for closing the on-off valve when the suction superheat degree calculated by the pressure becomes a predetermined value or less.

  According to a fourth aspect of the present invention, there is provided a discharge temperature sensor that detects a refrigerant discharge temperature of the discharge path of the compressor, and the on-off valve is open, and the refrigerant cylinder is empty when the refrigerant discharge temperature becomes a predetermined value or more. It is provided with a refrigerant cylinder empty detection means for judging that.

  According to a fifth aspect of the present invention, a receiver for storing high-pressure liquid refrigerant is provided, and one end is opened to an appropriate liquid surface position in the receiver, and the opening / closing valve, the pressure reducing mechanism, and the receiver are arranged in that order from the opening. A filling detection circuit having a supercooling heat exchanger is connected to the upstream path of the waste heat recovery unit, and a first temperature sensor is provided in the upstream path of the supercooling heat exchanger of the filling detection circuit, and the filling detection A second temperature sensor is provided in the downstream path of the supercooling heat exchanger of the circuit, and it is determined that the refrigerant charging is completed when the difference between the detected temperatures of the first temperature sensor and the second temperature sensor falls within a predetermined value. The filling detection means is provided.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, it is possible to prevent the compressor from getting wet by filling the refrigerant in the gas-liquid mixed state from the upstream side of the waste heat recovery unit and evaporating it in the waste heat recovery unit.

  According to the second aspect, in addition to the effect of the first aspect, it is possible to prevent the refrigerant remaining in the refrigerant circuit from being sealed after the refrigerant is charged.

  In the third aspect, in addition to the effect of the first aspect, the refrigerant charging circuit can be shut off immediately after the wetness detection, so that the compressor can be further prevented from getting wet.

  In the fourth aspect, in addition to the effect of the third aspect, the operator can detect at an early stage that the refrigerant cylinder has become empty during the refrigerant charging operation, and the man-hour for the confirmation operation can be omitted.

  According to the fifth aspect, in addition to the effect of the first aspect, the accuracy of charging an appropriate amount of additional refrigerant corresponding to different pipe lengths depending on the installation conditions is improved, and consequently, excessive additional refrigerant charging can be prevented.

Next, embodiments of the invention will be described.
FIG. 1 is a refrigerant circuit diagram illustrating an overall configuration of an engine-driven heat pump according to an embodiment of the present invention, and FIG. 2 is a refrigerant circuit diagram illustrating refrigerant behavior in a refrigerant charging operation state according to an embodiment of the present invention. FIG. 3 is a refrigerant circuit diagram showing the refrigerant behavior in the same state after completion of the refrigerant charging operation. FIG. 4 is a refrigerant circuit diagram illustrating the refrigerant behavior in a state where the refrigerant cylinder is removed after the refrigerant charging operation is completed.

  The refrigerant circuit configuration of an engine-driven heat pump 1 that is an embodiment of the present invention will be described with reference to FIG. In the present embodiment, for simplicity of explanation, the engine-driven heat pump 1 in which one indoor unit 3 is connected to one outdoor unit 2 is illustrated, but actually, one outdoor unit In many cases, a plurality of indoor units 3... 3 are connected to the unit 2.

  The engine-driven heat pump 1 includes a compressor 10 that obtains power from an engine (not shown) as a drive source and compresses the refrigerant, and is connected to the discharge side of the compressor 10 to flow the refrigerant during cooling and heating. A four-way valve 20 for switching, an outdoor heat exchanger 12 to which discharged refrigerant is supplied from the compressor 10 via the four-way valve 20 during cooling, an outdoor fan 5 for exchanging heat between the outdoor heat exchanger 12 and outdoor air, and heating An indoor heat exchanger 13 that is sometimes supplied with refrigerant discharged from the compressor 10 via the four-way valve 20, an indoor fan 6 that exchanges heat between the indoor heat exchanger 13 and indoor air, an outdoor heat exchanger 12 and indoor heat. It has the outdoor heat exchanger expansion valve 21 arrange | positioned between the exchangers 13, and uses the refrigerant cycle comprised by these.

  The compressor 10 sucks and compresses the gas refrigerant from the suction side and discharges the high-temperature and high-pressure gas refrigerant. The four-way valve 20 is connected to the discharge side of the compressor 10 via a path 60 that constitutes a discharge path. In this path 60, refrigeration oil contained in the gas refrigerant is separated and the compressor 10 is connected. An oil separator 11 for returning to the suction side is provided. That is, the gas refrigerant discharged from the compressor 10 flows into the four-way valve 20 through the oil separator 11 and is guided in a predetermined direction by the four-way valve 20. Further, since the gas refrigerant sucked into the compressor 10 is also guided by the four-way valve 20, the refrigerant suction side of the compressor 10 and the four-way valve 20 are connected by a path 61 that constitutes a suction path. The discharge temperature sensor 80 is provided on the compressor 10 side of the path 60 in order to detect the temperature of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10.

  The four-way valve 20 is connected to one end side of the outdoor heat exchanger 12, and a receiver 14 is connected to the other end side of the outdoor heat exchanger 12. On the other hand, one end of the indoor heat exchanger 13 is connected to the receiver 14 via the liquid side communication pipe 50, and the other end is connected to the four-way valve 20 via the gas side communication pipe 51. . In many cases, the liquid side communication pipe 50 and the gas side communication pipe 51 are installed inside a building, and recently, they may be used as they are when the air conditioner is updated. Further, a liquid closing valve 40 and a gas closing valve 41 are provided on the side of the outdoor unit 2 of these communication pipes 50 and 51, respectively. These liquid closing valve 40, gas closing valve 41, and closing valves 43 to 45 described later are constituted by ball valves and are manually opened and closed.

  The waste heat recovery unit 15 branches from the outdoor heat exchanger expansion valve 21 and the receiver 14 and is provided in a path 63 connected to the path 61. To the path 63, the waste heat recovery device expansion valve 22, the supercooling heat exchanger 17, and the waste heat recovery device 15 are connected in series toward the path 61. The refrigerant passing through the path 63 is supercooled by the supercooling heat exchanger 17 with the liquid refrigerant of the receiver 14 by latent heat of evaporation, and the waste heat of the engine is recovered from the engine cooling water by the waste heat recovery unit 15 and evaporated. .

The path 64 is a circuit for detecting the end of refrigerant charging. The path 64 is taken out from the bottom surface of the receiver 14 from an appropriate liquid surface position in the receiver 14. As will be described in detail later, the amount of refrigerant charged in the engine-driven heat pump 1 varies depending on the length of the communication pipes 50 and 51. Here, since the receiver 14 is a pressure vessel that stores liquid refrigerant, the engine-driven heat pump 1 has an appropriate liquid level position that indicates appropriate refrigerant amount filling. That is, no matter how long the connecting pipes 50 and 51 are installed, the appropriate refrigerant amount is determined by the appropriate liquid level position of the receiver 14 after installation.
The path 64 is connected between the waste heat recovery device expansion valve 22 and the supercooling heat exchanger 17 on the path 63 via the filling detection electromagnetic valve 30 and the capillary 26. The path 64 is a path used only for filling detection control described later, and the piping of the path 64 and the capillary 26 are selected so that the refrigerant circulation amount passing therethrough is smaller than that of the path 63.
Further, the first temperature sensor 83 and the second temperature sensor 84 are used for the filling detection control described later. The first temperature sensor 83 is provided on the upstream side of the supercooling heat exchanger 17 on the path 63. On the other hand, the second temperature sensor 84 is provided on the downstream side of the supercooling heat exchanger 17 on the path 63.

  A path 65 and a path 66 are bypass paths that short-circuit the path 60 that is the discharge path and the path 61 that is the suction path. The path 65 is provided with a bypass expansion valve 24 as a pressure reducing mechanism, and the path 66 is provided with a bypass electromagnetic valve 32. These bypass paths 65 and 66 prevent an abnormal increase in the high-pressure side pressure of the engine-driven heat pump 1 by short-circuiting the discharge gas of the compressor 10 and returning it to the suction path.

  The path 67 is a path from the upper surface of the receiver 14 toward the path 60 that is the discharge path. The path 67 can release the gas refrigerant to the discharge path when the high pressure of the receiver 14 rises abnormally. Further, the path 67 prevents the high-temperature and high-pressure discharged gas refrigerant from flowing back to the receiver 14 via the check valves 75 and 76.

The path 69 is a path that connects the refrigerant filling cylinder 91 and the path 63. The additional refrigerant can be charged from the refrigerant cylinder 91 through the path 69. Normally, the outdoor unit 2 is pre-filled with a standard amount of refrigerant at the time of shipment from the factory. However, if the connecting pipes 50 and 51 are long, an additional amount of refrigerant is required. In such a case, the refrigerant cylinder 91 is connected to the charge valve 42 via the charge hose 92 at the time of installation, and the refrigerant filling electromagnetic valve 31 is opened to fill the additional refrigerant via the path 69 (see FIG. 2). .
On the other hand, the path 68 is connected from the path 69 to the path 67 via the check valve 77. This path 68 is for allowing the refrigerant remaining in the path 69 at the end of the additional refrigerant charging to escape to the discharge side of the compressor 10 via the path 67.

The path 70 is connected in parallel to the path 61 that is the suction path via the oil tank 16. The oil tank 16 is a device that removes contaminants in the gas refrigerant, and its internal structure varies depending on the type of removal. As a removal method, a centrifugal separation method, a baffle method, or a wire mesh method is mainly used, and in this embodiment, the removal method is not particularly limited.
The path 70 is provided in parallel to the connection portion between the path 61 and the path 63. The path 70 is connected to the upper part of the oil tank 16 through the closing valve 43 from the outlet of the waste heat recovery unit 15, and is connected to the path 61 through the oil tank electromagnetic valve 34 and the closing valve 45 from the upper part of the oil tank 16. Is done. A path 71 is connected to the path 70 through the oil return solenoid valve 35 from the lower part of the oil tank 16. The gas refrigerant flows into the interior from above the oil tank 16, and after the contaminants are removed, it flows out again from above. The refrigerating machine oil that has dropped downward is returned to the path 70 by the path 71.
An intake temperature sensor 82 is provided on the path 63 between the waste heat recovery unit 15 and the connection between the path 70 and the path 63. That is, it is provided on the upstream side of the path 70. Further, a suction pressure sensor 85 is provided on the path 61.
The controller 100 detects the refrigerant state by using the temperature sensor and the pressure sensor, and performs opening / closing operation or opening / closing control of the electromagnetic valve, the electronic expansion valve, and the four-way valve. On the other hand, the closing valve is normally opened and closed by an operator's hand.

In the installation work of the engine-driven heat pump 1, the required pipe lengths of the communication pipes 50 and 51 used for connecting the outdoor unit 2 and the indoor unit 3 differ depending on the piping conditions at the installation site. However, in the process of factory production of the engine-driven heat pump 1, the outdoor unit 2 is filled with a predetermined amount of refrigerant in advance, and an insufficient amount of refrigerant is added according to the length of the connecting pipes 50 and 51 at the time of field installation. The refrigerant charging operation of charging is performed.
Below, in the refrigerant | coolant filling operation of the engine drive type heat pump 1 mentioned above, the superheat degree control during refrigerant | coolant filling operation, refrigerant | coolant cylinder empty detection control, completion | finish detection of filling, and the sealing prevention means of a residual refrigerant | coolant are demonstrated in order. The operation mode of the refrigerant charging operation may be a cooling operation, a heating operation, or an operation in which the outdoor unit 2 is a condenser and the waste heat recovery device 15 is an evaporator.

  In FIG. 2, a thick solid line indicates the refrigerant behavior in the refrigerant charging operation state. In this operating state, the outdoor heat exchanger 12 is a condenser, the indoor heat exchanger expansion valve 23 is fully opened, the indoor fan 6 is turned off, the heat exchange function of the indoor heat exchanger 13 is stopped, and the waste heat is recovered from the receiver 14. The compressor 10 is operated in a refrigerant circuit in which a long path to the compressor 15 is a decompression mechanism, the waste heat recovery device 15 is an evaporator, the shut-off valve 44 is closed, and the oil refrigerant is passed through the oil tank 16 to wash the gas refrigerant. To do.

Here, the refrigerant charging operation will be described.
As shown in FIG. 2, the refrigerant cylinder 91 is attached to the charge valve 42 via the charge hose 92, and the charge valve 42 and the refrigerant charging electromagnetic valve 31 are opened. And flows into the upstream side of the waste heat recovery unit 15. The refrigerant charged from the refrigerant cylinder 91 is in a gas-liquid mixed state.

The oil tank 16 removes contaminants such as the connecting pipes 50 and 51. When the liquid refrigerant flows into the oil tank 16, the refrigerant cannot return to the compressor 10. That is, when the liquid refrigerant flows into the oil tank 16, it is necessary to fill the refrigerant by that amount, and the appropriate accuracy of the filling amount is lowered. Moreover, since the path 70 having the oil tank 16 is used only when the refrigerant is charged, when the liquid refrigerant flows into the oil tank 16, the refrigerant is sealed after the completion of the filling operation. Further, even in the engine-driven heat pump 1 that is not provided with the oil tank 16, since the wet operation of the compressor 10 causes problems such as liquid compression and oil rise, the wet operation of the suction path 61 is similarly performed. There is a need to prevent.
Therefore, by joining the path 69, which is a refrigerant charging circuit, in the upstream path of the waste heat recovery unit 15, even if the refrigerant charged from the refrigerant cylinder 91 is gas-liquid mixed, the refrigerant is used as the waste heat recovery unit. At 15, the engine waste heat is recovered via the engine cooling water to become a gas refrigerant. That is, by allowing the charged refrigerant to pass through the waste heat recovery device 15, it is possible to prevent the liquid refrigerant from flowing into the oil tank 16, and thus the wet operation of the compressor 10 is prevented.

Further, in order to prevent the liquid refrigerant from flowing into the oil tank 16, the refrigerant flowing into the oil tank 16 is controlled to be a gas refrigerant having a degree of superheat greater than a predetermined value.
If the degree of superheat at the inlet of the oil tank 16 is equal to or less than a predetermined value, the controller 100 closes the refrigerant charging electromagnetic valve 31 and temporarily stops the refrigerant charging. The degree of superheat at the inlet of the oil tank 16 is calculated by calculating the saturation pressure equivalent temperature of the detection pressure of the suction pressure sensor 85 by the controller 100 and subtracting the saturation pressure equivalent temperature from the detection temperature of the suction temperature sensor 82. .

  In this way, the path 69 which is a refrigerant charging circuit is provided on the upstream side of the waste heat recovery unit 15, and if the degree of superheat is equal to or less than a predetermined value, the path 69 is directly blocked by the refrigerant charging electromagnetic valve 31, The inflow of liquid refrigerant into the oil tank 16 during the filling operation and the damp operation of the compressor 10 can be prevented.

  If the refrigerant cylinder 91 becomes empty during the above-described refrigerant charging operation, the refrigerant cylinder 91 needs to be replaced. Therefore, as the refrigerant cylinder empty state detection, if the discharge temperature sensor 80 is equal to or higher than a predetermined value, it is determined that the refrigerant cylinder 91 is empty. The determination display only needs to be confirmed by the operator. For example, there is a method of displaying a warning lamp on the operation unit.

  Conventionally, the operator has checked whether the refrigerant cylinder 91 remains during the refrigerant charging operation. By automatically notifying the operator of the empty state of the refrigerant cylinder 91 as in this embodiment, the remaining amount check can be omitted, and the workability of the field installation work of the engine-driven heat pump is improved.

With reference to FIG. 3, detection of the completion of charging for ending the refrigerant charging operation will be described. In addition, the thick line in FIG. 3 has shown the refrigerant | coolant behavior.
When the liquid level of the liquid refrigerant stored in the receiver 14 exceeds the appropriate liquid level position, the liquid refrigerant flows into the path 64. The liquid refrigerant expands in the capillary 26, evaporates due to the heat of the liquid refrigerant stored in the receiver 14 in the supercooling heat exchanger 17, becomes a gas refrigerant, and joins the waste heat recovery unit 15.
As described above, the first temperature sensor 83 and the second temperature sensor 84 are provided at the inlet and the outlet of the supercooling heat exchanger 17. Here, the temperature difference (hereinafter, temperature difference α) between the temperature detected by the first temperature sensor 83 and the temperature detected by the second temperature sensor 84 before and after the liquid refrigerant passes through the path 63 will be compared.
Before the liquid refrigerant passes through the path 63, the refrigerant hardly flows through the path 63, so there is almost no temperature difference α. When the liquid refrigerant passes through the path 63, it is expanded by the capillary 26 to be in a gas-liquid mixed state, deprived of heat in the supercooling heat exchanger 17, becomes superheated gas refrigerant, and flows into the waste heat recovery unit 15. Here, the temperature difference α corresponding to the degree of superheat between the gas refrigerant and the gas-liquid mixed refrigerant can be detected by the first temperature sensor 83 and the second temperature sensor 84 provided before and after the supercooling heat exchanger 17.
Therefore, as detection of the completion of charging, if the predetermined temperature difference α is calculated, the controller 100 determines that an appropriate amount of refrigerant has been filled in the refrigerant circuit of the engine-driven heat pump 1, and closes the refrigerant charging electromagnetic valve 31. The refrigerant charging is finished.

  As in this embodiment, by providing two temperature sensors before and after the supercooling heat exchanger 17 that is the evaporator of the path 63, it is ensured that the state where the refrigerant has steadily entered the capillary 26 has been reached. It is possible to detect, and it is possible to reliably detect the timing at which the liquid refrigerant constantly exceeds the appropriate liquid level position. As a result, erroneous detection due to sudden refrigerant intrusion into the capillary 26 can be prevented, so that the detection accuracy of the timing of completion of filling the appropriate refrigerant amount is improved.

FIG. 4 shows a state in which the refrigerant charging operation is finished. In the present embodiment, when the refrigerant charging operation is terminated, the controller 100 closes the refrigerant charging electromagnetic valve 31, then removes the charge hose 92, and the charge valve 42 is closed. At this time, since a closed circuit is formed between the charge valve 42 and the refrigerant charging electromagnetic valve 31 in the path 69, the residual refrigerant (thick line in FIG. 4) at the time of charging the refrigerant is in a sealed state.
When the sealed refrigerant absorbs heat from the surroundings and expands, the pressure becomes extremely high, causing cracks and breakage in the valves and piping.
Therefore, in the present embodiment, by providing the path 68 as a refrigerant escape circuit as a countermeasure for preventing sealing in the path 69, the refrigerant can escape from the path 68 to the path 67 (thick broken line in FIG. 4).

The refrigerant circuit figure which showed the whole structure of the engine drive type heat pump which concerns on the Example of this invention. The refrigerant circuit figure which showed the refrigerant | coolant behavior in the refrigerant | coolant filling operation state which is an Example of this invention. The refrigerant circuit figure which showed the refrigerant | coolant behavior of the refrigerant | coolant filling operation completion state similarly. Similarly, the refrigerant circuit diagram which showed the refrigerant | coolant behavior in the state which removed the refrigerant cylinder after completion | finish of a refrigerant | coolant filling operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine drive type heat pump 10 Compressor 14 Receiver 15 Waste heat recovery device 31 Refrigerant filling solenoid valve 60 Discharge route 61 Intake route 69 Route which is a refrigerant filling circuit 91 Refrigerant cylinder

Claims (5)

An engine driven compressor;
In an engine-driven heat pump having a waste heat recovery device that evaporates a refrigerant by waste heat of the engine,
An engine-driven heat pump characterized in that a refrigerant charging circuit having an on-off valve and a refrigerant cylinder mounting portion is joined in an upstream path of the waste heat recovery unit.   2. The engine-driven heat pump according to claim 1, wherein a refrigerant escape circuit is branched from a path connecting the on-off valve of the refrigerant charging circuit and a refrigerant cylinder mounting portion to a discharge path of the compressor. A suction temperature sensor for detecting a refrigerant suction temperature of a suction path of the compressor;
A suction pressure sensor for detecting a refrigerant suction pressure in the suction path of the compressor;
2. The engine according to claim 1, further comprising an on-off valve control means for closing the on-off valve when an intake superheat degree calculated from the refrigerant intake temperature and the refrigerant intake pressure becomes a predetermined value or less. Driven heat pump. A discharge temperature sensor for detecting a refrigerant discharge temperature of a discharge path of the compressor;
4. The engine-driven heat pump according to claim 3, further comprising refrigerant cylinder empty detecting means for determining that the refrigerant cylinder is empty when the on-off valve is open and the refrigerant discharge temperature reaches a predetermined value or more. . Provide a receiver to store high-pressure liquid refrigerant,
One end is opened with an appropriate liquid level position in the receiver, and in order from the opening, an on-off valve, a pressure reducing mechanism, and a filling detection circuit having a supercooling heat exchanger disposed inside the receiver are provided in the waste heat recovery unit. Connected to the upstream path,
A first temperature sensor is provided in the upstream path of the supercooling heat exchanger of the filling detection circuit,
A second temperature sensor is provided in the downstream path of the supercooling heat exchanger of the filling detection circuit,
2. The engine drive type according to claim 1, further comprising charging detection means for determining that the refrigerant charging is completed when a difference between detected temperatures of the first temperature sensor and the second temperature sensor falls within a predetermined value. heat pump.

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