JP4065313B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus including a compressor and an expander.

  In a so-called vapor compression refrigeration cycle apparatus, an apparatus having an expander instead of an expansion valve is known. In this type of refrigeration cycle apparatus, by using an expander, the expansion energy in the process of expansion of the refrigerant can be recovered in the form of electric power or mechanical force, and the efficiency of the cycle is improved by the amount of the recovered energy. Can do.

  In a refrigeration cycle apparatus equipped with an expander, lubricating oil is required not only for the compressor but also for the expander. In order to cope with this requirement, it is conceivable to increase the concentration of the lubricating oil mixed in the refrigerant and circulate through the refrigerant circuit and supply the lubricating oil to the expander. However, when the lubricating oil concentration in the refrigerant increases, the heat transfer coefficient on the refrigerant side in the heat exchanger decreases, and the refrigeration cycle performance decreases. Therefore, a refrigeration cycle apparatus in which an oil separator is provided on the refrigerant circuit has been proposed. For example, Japanese Patent Application Laid-Open No. 2003-240366 discloses a refrigeration provided with an oil separator provided between an expander and an evaporator, and an oil feed pipe connecting the oil separator and an inlet side pipe of a compressor. An air conditioner is disclosed.

  Furthermore, in the above document (FIG. 6), a heat exchanger in which the refrigerant and the lubricating oil between the radiator and the expander exchange heat is provided, and the lubricating oil in the oil separator and the liquid dissolved in the lubricating oil The structure which collect | recovers the refrigerating capacity with a refrigerant | coolant with the refrigerant | coolant between a heat radiator and an expander is proposed.

  However, in the refrigerating and air-conditioning apparatus disclosed in Japanese Patent Laid-Open No. 2003-240366, the heat exchange amount between the refrigerant and the lubricating oil, that is, the temperature of the lubricating oil returning to the compressor cannot be adjusted, and is sucked into the compressor at a high load. There is a possibility that the temperature of the refrigerant will rise and the temperature of the refrigerant discharged from the compressor will rise excessively. If the temperature of the refrigerant discharged from the compressor rises excessively, the seal member of the compressor is damaged and the lubricant is deteriorated, and the reliability of the compressor is lowered.

  Further, the temperature difference between the refrigerant temperature between the radiator and the expander and the lubricating oil separated by the oil separator disposed between the expander and the evaporator is small. For this reason, when the lubricant is heated by exchanging heat between the refrigerant between the radiator and the expander and the lubricant separated by the oil separator, there is a problem that the capacity of the heater increases. .

  The present invention has been made in view of such a point, and an object of the present invention is to appropriately control the temperature of the lubricating oil returned to the compressor to prevent an excessive increase in the temperature of the refrigerant discharged from the compressor. At the same time, heat exchange is performed between the refrigerant and the lubricating oil between the compressor and the radiator, thereby increasing the temperature difference between the refrigerant and the lubricating oil and reducing the size of the heater.

That is, the present invention
A refrigerant circuit in which a compressor, a radiator, an expander, an oil separator and an evaporator are connected in this order;
An oil supply passage provided separately from the refrigerant circuit, for supplying the lubricating oil separated by the oil separator between the evaporator and the compressor in the compressor or refrigerant circuit;
A heater for heating the lubricating oil in the oil supply passage;
A flow rate adjusting means for adjusting the flow rate of the lubricating oil in the oil supply passage;
A refrigeration cycle apparatus comprising:

  According to the above refrigeration cycle apparatus, since the oil separator is provided in the refrigerant circuit, the amount of lubricating oil flowing into the evaporator can be reduced. Thereby, the heat transfer performance on the refrigerant side in the evaporator can be improved, and the efficiency of the refrigeration cycle can be improved. Further, the heat exchange amount between the lubricating oil and the refrigerant in the heater can be adjusted by the flow rate adjusting means. As a result, an appropriate amount and temperature of lubricating oil can be supplied to the compressor, and an excessive increase in the temperature of the refrigerant discharged from the compressor can be prevented, thereby improving the reliability of the compressor. Moreover, since the temperature difference between the refrigerant discharged from the compressor and the lubricating oil separated by the oil separator is large, the heater that exchanges heat between the refrigerant and the lubricating oil can be downsized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, a refrigeration cycle apparatus 10A according to Embodiment 1 includes a refrigerant circuit 11 in which a compressor 1, a radiator 2, an expander 3, an oil separator 9, and an evaporator 5 are connected in this order. It has. The refrigeration cycle apparatus 10 </ b> A includes an oil supply pipe 7 as an oil supply passage for supplying the lubricating oil of the oil separator 9 to the compressor 1. The oil supply pipe 7 is a pipe provided separately from the refrigerant pipe of the refrigerant circuit 11. One end of the oil supply pipe 7 is connected to the oil separator 9, and the other end is connected to the inlet side pipe 13 of the compressor 1 (that is, the refrigerant pipe between the evaporator 5 and the compressor 1). The oil supply pipe 7 is provided with a heater 6A and a valve 8. The valve 8 is a valve whose opening degree can be controlled, and is configured as a flow rate adjusting means for adjusting the flow rate of the lubricating oil flowing through the oil supply pipe 7 by the opening degree control.

The refrigerant filled in the refrigerant circuit 11 is a refrigerant that becomes a supercritical state in a high-pressure portion (portion from the compressor 1 through the radiator 2 to the expander 3) during operation. The refrigerant circuit 11 of the first embodiment is filled with carbon dioxide (CO ₂ ) as such a refrigerant. However, the type of refrigerant is not particularly limited.

  For the compressor 1, for example, a rotary compressor, a scroll compressor, or the like can be suitably used. However, the format of the compressor 1 is not limited at all.

  The type of the expander 3 is not limited at all. As the expander 3, for example, an expander provided with an expansion mechanism such as a rotary type or a scroll type can be suitably used.

  A power generator 4 is connected to the expander 3. The generator 4 converts the expansion energy of the refrigerant recovered by the expander 3 into electric energy. In FIG. 1, the generator 4 and the expander 3 are illustrated separately, but the generator 4 may be built in the expander 3.

  Further, the motor drive shaft of the compressor 1 and the drive shaft of the expander 3 may be connected. That is, it is possible to employ an expander-integrated compressor having a structure in which the compressor 1 and the expander 3 are arranged in the same hermetic container and are connected and integrated by a drive shaft in the refrigeration cycle apparatus 10A. it can. At this time, the generator 4 is not required.

  The configurations of the radiator 2 and the evaporator 5 are not limited at all. For example, an air-cooled or water-cooled heat exchanger may be used as the radiator 2 or the evaporator 5.

  The configuration of the oil separator 9 is not particularly limited, but since the refrigerant discharged from the expander 3 is in a gas-liquid two-phase state, the lubricating oil can be efficiently separated from the gas-liquid two-phase refrigerant. Is desired. Focusing on the fact that the specific gravity of the lubricating oil is greater than that of the liquid refrigerant, for example, an oil separator 9 having a structure as shown in FIG. 7 can be suitably employed. The oil separator 9 shown in FIG. 7 includes a container 19 that receives the refrigerant discharged from the expander 3 and allows it to stand still. An oil supply pipe 7 is connected to the bottom of the container 19, and a side wall of the container 19 has a bifurcated structure for sending liquid refrigerant 21 L and gaseous refrigerant 21 G stored on the lubricating oil 20 to the evaporator 5. Refrigerant piping 11p is connected.

  The heater 6 </ b> A directly exchanges heat between the lubricating oil in the oil supply pipe 7 and the high-pressure refrigerant between the compressor 1 and the radiator 2. The temperature difference between the high-temperature and high-pressure refrigerant between the compressor 1 and the radiator 2 and the lubricating oil flowing through the oil supply pipe 7 is large. Therefore, as described in Japanese Patent Application Laid-Open No. 2003-240366, compared with the case where heat is exchanged between the low-temperature and high-pressure refrigerant discharged from the radiator and the lubricating oil flowing through the oil supply pipe, the heater 6A. Is small.

  For the heater 6A, for example, a double tube heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, or the like can be suitably used. Further, without using a dedicated heat exchanger, for example, the oil supply pipe 7 and the refrigerant pipe of the refrigerant circuit 11 are arranged in parallel and brought into contact with each other. It is also possible to configure 6A.

  When a double tube heat exchanger having an inner flow path and an outer flow path is used as the heater 6A, a coolant may flow through the inner flow path and lubricating oil may flow through the outer flow path. This can suppress an increase in pressure loss of the high-pressure refrigerant. Conversely, it is possible to flow lubricating oil in the inner flow path and flow refrigerant in the outer flow path. In this case, the pressure loss of the lubricating oil is reduced, and a sufficient flow rate of the lubricating oil can be ensured. Note that the heater 6A is preferably a so-called counterflow type heat exchanger in which the refrigerant and the lubricating oil are circulated in an opposed state.

  An inlet temperature sensor 12 that detects the temperature of the refrigerant sucked into the compressor 1 is provided in the inlet side pipe 13 of the compressor 1 that is a part of the refrigerant pipe of the refrigerant circuit 11. The evaporator 5 is provided with an evaporation temperature sensor 14 for detecting the evaporation temperature of the refrigerant. The suction temperature sensor 12 and the evaporation temperature sensor 14 may be any sensor that substantially detects the refrigerant temperature. Therefore, the suction temperature sensor 12 and the evaporation temperature sensor 14 may directly detect the refrigerant temperature in the pipe, and indirectly detect the refrigerant temperature by detecting the wall surface temperature of the pipe. May be. The evaporation temperature sensor 14 only needs to be able to detect the evaporation temperature of the low-pressure side refrigerant, and may be provided between the expander 3 and the evaporator 5.

  Further, a controller 15 is provided in the refrigeration cycle apparatus 10A. The controller 15 receives detection signals from the suction temperature sensor 12 and the evaporation temperature sensor 14 and identifies detection values (detection temperatures) from the sensors 12 and 14. Then, the opening degree of the valve 8 is controlled based on the identified detection value. Thereby, the difference between the temperature of the refrigerant sucked into the compressor 1 and the evaporation temperature of the refrigerant in the evaporator 5, so-called superheat degree, can be appropriately controlled. Appropriate control of the degree of superheat can prevent an excessive increase in the temperature of the refrigerant discharged from the compressor. Of course, the controller 15 does not have to be a dedicated controller provided for controlling the valve 8 and may control the compressor 1 or the like.

  The suction temperature sensor 12 is disposed on the compressor 1 side as viewed from the junction of the inlet side pipe 13 and the oil supply pipe 7 of the compressor 1. If the suction temperature sensor 12 is arranged at such a position, the temperature of the refrigerant immediately before being sucked into the compressor 1 can be accurately measured.

  Next, the operation of the refrigeration cycle apparatus 10A will be described. In the refrigerant circuit 11, the refrigerant discharged from the compressor 1 heats the lubricating oil by the heater 6A and at the same time releases heat. Further, the refrigerant dissipates heat in the radiator 2, expands in the expander 3, and then separated from the lubricating oil in the oil separator 9. Next, the refrigerant absorbs heat in the evaporator 5 and is then sucked into the compressor 1.

  On the other hand, the lubricating oil separated by the oil separator 9 flows through the oil supply pipe 7 and is heated by exchanging heat with the refrigerant in the heater 6A. Then, the heated lubricating oil flows into the inlet side pipe 13 of the compressor 1, merges with the refrigerant from the evaporator 5, and flows into the compressor 1. Thereby, lubricating oil is supplied to the compressor 1. The flow rate of the lubricating oil is adjusted by the valve 8.

  The controller 15 controls the opening degree of the valve 8 based on the refrigerant temperature at the inlet of the compressor 1 and the refrigerant evaporation temperature in the evaporator 5. As described above, since the lubricating oil in the oil supply pipe 7 is heated by the heater 6A, the temperature of the refrigerant and the lubricating oil flowing into the compressor 1 increases as the amount of the lubricating oil flowing into the heater 6A increases. Become. Therefore, in the first embodiment, the controller 15 causes the degree of superheat, which is the difference between the refrigerant temperature at the inlet of the compressor 1 and the refrigerant evaporation temperature in the evaporator 5, to approach a predetermined value (target value). Thus, the opening degree of the valve 8 is controlled. For example, the controller 15 decreases the opening degree of the valve 8 when the degree of superheat is equal to or greater than a predetermined value, and increases the opening degree of the valve 8 when the degree of superheat is less than a predetermined value.

  Alternatively, the opening degree of the valve 8 may be controlled so that the degree of superheat falls within a predetermined range (within a target range). When the degree of superheat exceeds a predetermined range, the opening degree of the valve 8 is decreased, and when the degree of superheat is less than the predetermined range, the opening degree of the valve 8 is increased. In this way, the valve 8 can be prevented from constantly opening and closing, and the possibility of failure of the valve 8 can be reduced. In addition, you may change the target value or target range of a superheat degree according to the driving | running state of 10 A of refrigeration cycle apparatuses.

  As described above, according to the first embodiment, since the lubricating oil in the oil supply pipe 7 is heated with the high-pressure refrigerant between the compressor 1 and the radiator 2, the heater 6A can be downsized. . Further, the refrigeration capacity of the lubricating oil and the liquid refrigerant dissolved in the lubricating oil can be recovered in the refrigerant circuit, and the refrigeration efficiency of the entire cycle can be improved. Furthermore, by controlling the opening degree of the valve 8, the degree of superheat can always be controlled within a predetermined value or a predetermined range, so that the danger of the compressor 1 performing liquid compression can be avoided.

  That is, in this refrigeration cycle apparatus 10A, by cooling the high-pressure refrigerant with lubricating oil, the pressure in the high-pressure portion of the refrigerant circuit 11 can be reduced, and the load on the compressor 1 can be reduced. Therefore, COP (coefficient of performance) of the refrigeration cycle, specifically, COP when cooling an object such as air or water can be improved. Moreover, since a refrigerant | coolant is cooled in the heater 6A, the required heat dissipation in the heat radiator 2 can be reduced. Therefore, it is possible to make the radiator 2 compact.

  Further, according to the first embodiment, since the valve 8 capable of controlling the opening degree is provided in the oil supply pipe 7, the supply amount of the lubricating oil to the heater 6A can be freely adjusted. Further, the degree of superheat of the refrigerant sucked into the compressor 1 is controlled by controlling the opening degree of the valve 8 based on the refrigerant temperature at the inlet of the compressor 1 and the refrigerant evaporation temperature in the evaporator 5. Can do. Therefore, the danger that the compressor 1 performs liquid compression can be avoided, and the reliability of the compressor 1 can be improved. Therefore, it is possible to achieve a high degree of compatibility between the refrigeration efficiency and the improvement of the reliability of the compressor 1.

  Further, the refrigerant after being separated from the lubricating oil by the oil separator 9 flows through the evaporator 5. Therefore, since it can suppress that lubricating oil flows into the evaporator 5, the heat transfer rate by the side of the refrigerant | coolant of the evaporator 5 can be raised, and the performance of the evaporator 5 can be improved. Therefore, the refrigeration efficiency can be further improved.

(Embodiment 2)
As shown in FIG. 2, the refrigeration cycle apparatus 10B of the second embodiment further includes a discharge temperature sensor 16 that detects the temperature of the refrigerant discharged from the compressor 1 in addition to the refrigeration cycle apparatus 10A of the first embodiment. While providing, it replaces with heater 6A and employs heater 6B.

  A controller 15 is provided in the refrigeration cycle apparatus 10B. The controller 15 receives detection signals from the suction temperature sensor 12, the evaporation temperature sensor 14, and the discharge temperature sensor 16, and controls the opening degree of the valve 8. The controller 15 does not have to be a dedicated controller provided for controlling the valve 8 and may be used as a controller for controlling the compressor 1.

  The controller 15 includes a refrigerant temperature T1 sucked into the compressor 1 (referred to as a suction temperature T1), a refrigerant temperature T2 discharged from the compressor 1 (referred to as a discharge temperature T2), and a refrigerant evaporation temperature in the evaporator 5. The opening degree of the valve 8 is controlled based on T3. FIG. 3 is a flowchart for controlling the valve 8 by the controller 15. The control represented by this flowchart is repeatedly performed at regular intervals, for example.

  In step S1, the controller 15 determines whether or not the discharge temperature T2 is equal to or higher than a predetermined value Tb. When it is determined that the discharge temperature T2 is equal to or higher than the predetermined value Tb, the opening degree of the valve 8 is decreased in step S4. When the opening degree of the valve 8 is decreased, the degree of superheat TSH represented by (T1-T3) is decreased. As the superheat degree TSH decreases, the discharge temperature T2 decreases. Therefore, damage to the seal member of the compressor 1 and deterioration of the lubricating oil due to the excessive increase in the discharge temperature T2 can be avoided.

  In S1, when it is determined that the discharge temperature T2 is lower than the predetermined value Tb, the process proceeds to step S2, and it is determined whether the superheat degree TSH is equal to or higher than a predetermined value Ta. When it is determined that the degree of superheat TSH is equal to or greater than the predetermined value Ta, the opening degree of the valve 8 is decreased in step S4. As a result, the degree of superheat TSH decreases and the discharge temperature T2 decreases, so that damage to the seal member of the compressor 1 and deterioration of the lubricating oil due to excessive increase in the discharge temperature T2 can be avoided. On the other hand, if it is determined in step S2 that the degree of superheat TSH is less than the predetermined value Ta, the opening degree of the valve 8 is increased in step S3. As a result, the degree of superheat TSH rises and approaches the predetermined value Ta, thereby increasing the efficiency of the refrigeration cycle.

  Thus, by controlling the valve 8 based on the refrigerant temperature T1 at the inlet of the compressor 1 and the refrigerant evaporation temperature T3 in the evaporator 5, the superheat degree TSH of the refrigerant sucked by the compressor 1 is set to a predetermined value. Control close to Ta can be performed. Further, in the second embodiment, the discharge temperature T2 of the compressor 1 is detected, and when the discharge temperature T2 becomes equal to or higher than the predetermined value Tb, the opening degree of the valve 8 is decreased and the degree of superheat TSH is decreased. . As a result, the temperature T2 of the refrigerant discharged from the compressor 1 is reduced, and the discharge temperature T2 is excessively increased, so that damage to the seal member of the compressor 1 and deterioration of the lubricating oil can be avoided. In particular, the effect becomes remarkable under high load conditions in which the difference between the high and low pressures of the refrigeration cycle is large, and the applications and installation conditions to which this refrigeration cycle apparatus can be applied are expanded.

  In addition, the said control can be suitably employ | adopted not only in this Embodiment 2 but other embodiment.

  The heater 6B according to the second embodiment also uses the high-pressure refrigerant in the refrigerant circuit 11 to cool the lubricating oil in the oil supply pipe 7, but the configuration is different from that in the first embodiment. The heater 6B of the second embodiment is configured to indirectly exchange heat between the lubricating oil and the high-pressure refrigerant. Specifically, the radiator 2 according to the second embodiment is a so-called air heat exchanger that exchanges heat between air and refrigerant, and the heater 6B is air (heated outside air) before being heated by the radiator 2. ) And the lubricating oil. The air after passing through the air heat exchanger that constitutes the heater 6 </ b> B flows into the air heat exchanger that constitutes the radiator 2. The refrigeration cycle apparatus 10B of the second embodiment is further provided with a blower 17 common to the radiator 2 and the heater 6B. Thereby, heat exchange efficiency increases. However, it goes without saying that a blower may be provided in each of the radiator 2 and the heater 6B.

  Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained.

(Embodiment 3)
As shown in FIG. 4, the refrigeration cycle apparatus 10C of the third embodiment employs a heater 6C instead of the heater 6A of the refrigeration cycle apparatus 10A of the first embodiment. In the third embodiment, the heater 6C is integrated with the radiator 2, that is, the heater 6C is also used as the radiator 2. The oil supply pipe 7 passes through the radiator 2, and the refrigerant flowing into the radiator 2 (or air before being heated by the refrigerant or air after being heated) and the lubricating oil exchange heat. Other configurations are the same as those of the first embodiment. In FIG. 4, the suction temperature sensor 12, the evaporation temperature sensor 14, and the controller 15 are not shown.

  Therefore, also in the third embodiment, the same effect as in the first embodiment can be obtained.

(Embodiment 4)
In the first to third embodiments, the oil supply pipe 7 is provided with the valve 8. As shown in FIG. 5, the refrigeration cycle apparatus 10 </ b> D of the fifth embodiment is provided with an oil pump 8 a instead of the valve 8 (or together with the valve 8). The controller 15 controls the oil pump 8 a based on the refrigerant temperature at the inlet of the compressor 1 and the refrigerant evaporation temperature in the evaporator 5.

  By providing the oil pump 8a in the oil supply pipe 7, the flow rate of the lubricating oil in the oil supply pipe 7 can be reduced even when the pressure difference between the oil separator 9 and the inlet side pipe 13 of the compressor 1 is small. Can do a lot. Therefore, it becomes possible to control the flow rate of the lubricating oil widely.

(Embodiment 5)
As shown in FIG. 6, the refrigeration cycle apparatus 10E according to the fifth embodiment has an oil supply pipe branched between an oil separator 9 and a heater 6A. That is, the oil supply pipes 17 and 27 as the oil supply passages are separated from the main supply pipe 17 as the main passage where the heater 6A is disposed and the oil separator 9 by branching from the main supply pipe 17. It is comprised from the auxiliary | assistant supply pipe | tube 27 as an auxiliary | assistant channel | path which can be supplied between the evaporator 5 and the compressor 1 in the refrigerant circuit 11 without heating oil with the heater 6A. The sub supply pipe 27 branched from the main supply pipe 17 between the oil separator 9 and the heater 6A is joined again with the main supply pipe 17 on the downstream side of the heater 6A, and the main supply pipe 17 is connected to the compressor. 1 to the inlet side piping 13. However, the sub supply pipe 27 may be directly connected to the inlet side pipe 13 without joining the main supply pipe 17.

  Further, as the flow rate adjusting means, the first valve 18 is disposed on the main supply pipe 17 between the branch point where the sub supply pipe 27 branches from the main supply pipe 17 and the heater 6A, and the second valve 28 is provided. It is arranged on the sub supply pipe 27. Each of the first valve 18 and the second valve 28 is a valve whose opening degree can be controlled, and the flow rate of the lubricating oil flowing through the main supply pipe 17 and the lubricating oil flowing through the auxiliary supply pipe 27 are controlled by the opening degree. The flow rate can be adjusted. The controller 15 adjusts the flow rate of the lubricating oil in the main supply pipe 17 and the flow rate of the lubricating oil in the sub supply pipe 27 to be interlocked with each other by controlling to open and close the first valve 18 and the second valve 28 in conjunction with each other. To do.

  Now, consider the refrigeration cycle apparatus that does not have the auxiliary supply pipe 27, that is, the refrigeration cycle apparatuses 10A and 10B of the first and second embodiments. As described with reference to the flowchart of FIG. 3, the opening degree of the valve 8 is reduced under conditions where the degree of superheat TSH is equal to or greater than the predetermined value Ta (for example, at high outside air temperature). Then, since the flow resistance value of the oil supply pipe 7 toward the heater 6 </ b> A increases, the lubricating oil flows through the evaporator 5 instead of the oil supply pipe 7 and returns to the compressor 1. When lubricating oil enters the evaporator 5, the heat transfer coefficient on the refrigerant side in the evaporator 5 decreases, and the problem that the heat transfer performance deteriorates becomes surface again.

  Therefore, if the auxiliary supply pipe 27 is provided as in the fifth embodiment and the lubricating oil that cannot flow into the main supply pipe 17 is returned to the compressor 1 using the auxiliary supply pipe 27, the refrigerant side in the evaporator 5 It is possible to appropriately control the degree of superheat TSH without causing a decrease in the heat transfer coefficient.

  The specific control procedure is as follows. First, the opening degree of the first valve 18 is controlled according to the superheat degree TSH, as described with reference to FIG. On the other hand, the opening degree of the second valve 28 is controlled so that the flow resistance value of the entire oil supply pipe is always constant. That is, control is performed to reduce the opening of the other in conjunction with increasing the opening of one of the valves. However, the opening degree of the first valve 18 and the opening degree of the second valve 28 can be independently controlled.

(Other embodiments)
In the above embodiments, the downstream ends of the oil supply pipes 7, 17, and 27 are connected to the inlet side pipe 13 of the compressor 1. However, the oil supply pipes 7, 17, and 27 only need to supply lubricating oil to the compressor 1, and the downstream ends of the oil supply pipes 7, 17, and 27 may be connected to the compressor 1 itself. In this case, the valves 8, 18, 28 and the oil pump 8a can be controlled based on the temperature of the refrigerant discharged from the compressor 1.

  When there is no need to control the flow rate of the lubricating oil in the oil supply pipes 7, 17, 27, a throttle mechanism such as a capillary tube is provided in place of the valves 8, 18, 28 with adjustable opening. Also good.

  The types of the oil supply pipes 7, 17, and 27 are not limited at all. The oil supply pipes 7, 17, and 27 may be formed of a flexible pipe so that the oil supply pipes 7, 17, and 27 are not easily damaged by vibration of the compressor 1 or the expander 3. Further, the length and shape of the oil supply pipes 7, 17, and 27 are not limited at all. However, from the viewpoint of reducing the pressure loss of the oil supply pipes 7, 17, and 27, the oil supply pipes 7, 17, and 27 are preferably shorter in length, and are preferably straight pipes.

  The refrigerant charged in the refrigerant circuit is not limited to a refrigerant that is in a supercritical state in the high-pressure portion of the refrigerant circuit, and may be a refrigerant that does not enter a supercritical state in the high-pressure portion.

  As described above, the present invention is useful for a refrigeration cycle apparatus including a compressor and an expander.

Refrigerant circuit diagram of refrigeration cycle apparatus according to Embodiment 1 Refrigerant circuit diagram of refrigeration cycle apparatus according to Embodiment 2 Valve control flowchart in the second embodiment Refrigerant circuit diagram of refrigeration cycle apparatus according to Embodiment 3 Refrigerant circuit diagram of refrigeration cycle apparatus according to Embodiment 4 Refrigerant circuit diagram of refrigeration cycle apparatus according to Embodiment 5 Schematic diagram of oil separator

Claims (10)

A refrigerant circuit in which a compressor, a radiator, an expander, an oil separator and an evaporator are connected in this order;
An oil supply passage provided separately from the refrigerant circuit, for supplying the lubricating oil separated by the oil separator between the evaporator and the compressor in the compressor or the refrigerant circuit;
A heater for heating the lubricating oil in the oil supply passage;
Flow rate adjusting means for adjusting the flow rate of the lubricating oil in the oil supply passage;
An evaporation temperature sensor for detecting the evaporation temperature of the refrigerant in the evaporator;
A suction temperature sensor for detecting the temperature of the refrigerant sucked into the compressor;
A controller for controlling the flow rate adjusting means based on a detection value of the evaporation temperature sensor and a detection value of the suction temperature sensor;
A refrigeration cycle apparatus comprising:   The refrigeration cycle apparatus according to claim 1, wherein the heater includes a heat exchanger that exchanges heat between the refrigerant between the compressor and the radiator and the lubricating oil in the oil supply passage. A refrigerant circuit in which a compressor, a radiator, an expander, an oil separator and an evaporator are connected in this order;
An oil supply passage provided separately from the refrigerant circuit, for supplying the lubricating oil separated by the oil separator between the evaporator and the compressor in the compressor or the refrigerant circuit;
A heater for heating the lubricating oil in the oil supply passage;
A flow rate adjusting means for adjusting the flow rate of the lubricating oil in the oil supply passage,
The heater comprises a heat exchanger for the lubricating oil of the outside air and the oil supply passage to heat exchange, the ambient air after passing through the heat exchanger flows into the radiator, the refrigeration cycle apparatus. A refrigerant circuit in which a compressor, a radiator, an expander, an oil separator and an evaporator are connected in this order;
An oil supply passage provided separately from the refrigerant circuit, for supplying the lubricating oil separated by the oil separator between the evaporator and the compressor in the compressor or the refrigerant circuit;
A heater for heating the lubricating oil in the oil supply passage;
A flow rate adjusting means for adjusting the flow rate of the lubricating oil in the oil supply passage,
The heater, being also used as the radiator performs heat exchange with the refrigerant lubricating oil of the oil supply passage flows into the radiator, the refrigeration cycle apparatus. A refrigerant circuit in which a compressor, a radiator, an expander, an oil separator and an evaporator are connected in this order;
An oil supply passage provided separately from the refrigerant circuit, for supplying the lubricating oil separated by the oil separator between the evaporator and the compressor in the compressor or the refrigerant circuit;
A heater for heating the lubricating oil in the oil supply passage;
A flow rate adjusting means for adjusting the flow rate of the lubricating oil in the oil supply passage,
The oil supply passage includes a main passage in which the heater is disposed, and the evaporation in the refrigerant circuit without heating the lubricant separated by the oil separator by branching from the main passage by the heater. A sub-passage that can be supplied between the compressor and the compressor,
The refrigeration cycle apparatus , wherein the flow rate adjusting means is configured to be able to adjust the flow rate of the lubricating oil in the main passage and the flow rate of the lubricating oil in the sub passage.   The flow rate adjusting means includes a first valve disposed on the main passage between a branch point of the sub passage and the heater, and a second valve disposed on the sub passage. 5. The refrigeration cycle apparatus according to 5.   The controller further includes a controller that adjusts the flow rate of the lubricating oil in the main passage and the flow rate of the lubricating oil in the sub-passage in association with each other by controlling to open and close the first valve and the second valve. The refrigeration cycle apparatus according to claim 6. An evaporation temperature sensor for detecting the evaporation temperature of the refrigerant in the evaporator;
A suction temperature sensor for detecting the temperature of the refrigerant sucked into the compressor;
A controller for controlling the flow rate adjusting means based on a detection value of the evaporation temperature sensor and a detection value of the suction temperature sensor;
The refrigeration cycle apparatus according to any one of claims 3 to 5 , further comprising: Instead of the evaporating temperature sensor and the suction temperature sensor, a discharge temperature sensor for detecting the temperature of the refrigerant discharged from the compressor is further provided,
The refrigeration cycle apparatus according to claim 1 or 8 , wherein the controller controls the flow rate adjusting means based on a detection value of the discharge temperature sensor . The refrigeration cycle apparatus according to any one of claims 1 to 9, wherein a refrigerant in a high-pressure portion from the compressor to the expander through the radiator in the refrigerant circuit is in a supercritical state.

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