JP5982290B2 - Dual refrigeration cycle equipment - Google Patents

Description

  Embodiments of the present invention relate to a dual refrigeration cycle apparatus including a high temperature side refrigeration cycle and a low temperature side refrigeration cycle in the same housing.

  A high-temperature side refrigeration cycle and a low-temperature side refrigeration cycle are provided in the same casing, and the high-temperature side refrigerant circulating in the high-temperature side refrigeration cycle and the low-temperature side refrigerant circulating in the low-temperature side refrigeration cycle are heat-exchanged by a cascade heat exchanger. Therefore, there is a tendency that a binary refrigeration cycle apparatus that obtains a high compression ratio is frequently used.

  When this dual refrigeration cycle apparatus is used as a hot water supply system, the high temperature side condenser constituting the high temperature side refrigeration cycle is used as a water / refrigerant heat exchanger, and the high temperature side refrigerant led here and water led from the hot water pipe or Heat is exchanged with hot water, and the water or hot water led to the hot water pipe is heated and supplied.

JP 2010-196952 A

  By the way, in the high temperature side compressor constituting the high temperature side refrigeration cycle and the low temperature side compressor constituting the low temperature side refrigeration cycle, lubricating oil is collected and supplied to each sliding portion inside the compressor. While each compressor is stopped, the temperature is low, and refrigerant is dissolved in the lubricating oil. Therefore, lubricating oil is diluted with a refrigerant | coolant, its viscosity is low and lubricity is bad.

  In view of configuring the hot water supply system, in particular, in the high temperature side refrigeration cycle, it is necessary to quickly raise the temperature of water or hot water led to the hot water pipe. To that end, when the high temperature side compressor starts up, the temperature of the collected lubricating oil is quickly raised, the refrigerant dissolved in this is separated to suppress dilution of the lubricating oil, and the viscosity is increased to shift to stable operation. It is desirable to do.

  Further, if the stable operation state is continued for a long time, the temperature of the high-temperature side compressor rises more than necessary, and the sliding portion is overheated, and the motor efficiency tends to decrease. Therefore, it is necessary to improve the motor efficiency and reliability by cooling the high temperature side compressor this time.

  For this reason, at the time of start-up, the temperature of the lubricating oil collected in the high-temperature side compressor is quickly raised, the dilution with the refrigerant is suppressed, the viscosity is increased, and the reliability is improved. There is a need for a dual refrigeration cycle apparatus that can shift to stable operation and continue long-term stable operation to cool the high-temperature side compressor and suppress overheating of the sliding portion to improve motor efficiency.

  According to the present embodiment, the high temperature side compressor, the high temperature side condenser, the high temperature side expansion device, and the cascade heat exchanger communicate with each other via the refrigerant pipe, the high temperature side refrigeration cycle, the low temperature side compressor, and the cascade heat exchanger. A low temperature side expansion device, a low temperature side evaporator, and a low temperature side refrigeration cycle communicating with each other via a refrigerant pipe in the same housing, and a high temperature side refrigerant guided to the high temperature side refrigeration cycle, and the low temperature side A low temperature side refrigerant led to a refrigeration cycle is a two-way refrigeration cycle device for exchanging heat with the cascade heat exchanger, wherein the low temperature side compressor of the low temperature side refrigeration cycle passes through the cascade heat exchanger The refrigerant pipe leading to the low temperature side expansion device is a low temperature side high pressure portion, and the low temperature side high pressure portion is extended to the high temperature side compressor constituting the high temperature side refrigeration cycle, so that the heat and high temperature of the low temperature side refrigerant are increased. The compressor is provided with heat exchange means for heat exchange.

The refrigeration cycle block diagram of the two-way refrigeration cycle apparatus based on 1st Embodiment. The front view of the high temperature side compressor based on the embodiment. The longitudinal cross-sectional view of the high temperature side compressor of the modification based on the embodiment. The refrigeration cycle block diagram of the binary refrigeration cycle apparatus based on 2nd Embodiment. The refrigeration cycle block diagram of the binary refrigeration cycle apparatus based on 3rd Embodiment.

Hereinafter, the present embodiment will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a refrigeration cycle of a binary refrigeration cycle apparatus N used as, for example, a hot water supply system in the first embodiment.

The dual refrigeration cycle apparatus N includes a high temperature side refrigeration cycle Ra, a low temperature side refrigeration cycle Rb, a hot water pipe H, and a control unit S mounted in the same housing K.
In the high temperature side refrigeration cycle Ra, the discharge section a of the high temperature side compressor 1 and the primary side flow path 2a of the water / refrigerant heat exchanger 2 which is a high temperature side condenser are connected via a high temperature side refrigerant pipe Pa, The primary side flow path 2a of the water / refrigerant heat exchanger 2 and the high temperature side expansion device 3 are connected via a high temperature side refrigerant pipe Pa.

  The primary side flow path 4a of the high temperature side expansion device 3 and the cascade heat exchanger 4 is connected via the high temperature side refrigerant pipe Pa, and the primary side flow path 4a of the cascade heat exchanger 4 and the suction of the high temperature side compressor 1 are connected. The part b is connected via the high temperature side refrigerant | coolant piping Pa.

  In the low temperature side refrigeration cycle Rb, the discharge part a of the low temperature side compressor 5 and the secondary side flow path 4b of the cascade heat exchanger 4 are connected via a low temperature side refrigerant pipe Pb configured as will be described later. The secondary side flow path 4b of the heat exchanger 4 and the low temperature side expansion device 6 are connected via a low temperature side refrigerant pipe Pb.

  The low temperature side expansion device 6 and the air heat exchanger 7 which is a low temperature side evaporator are connected via a low temperature side refrigerant pipe Pb, and the air heat exchanger 7 and the suction part b of the low temperature side compressor 5 are connected to the low temperature side refrigerant pipe. It is connected via Pb. A blower is disposed opposite the air heat exchanger 7 so as to blow air for heat exchange.

  Here, the system path of the low-temperature side refrigerant pipe Pb from the discharge part a of the low-temperature side compressor 5 of the low-temperature side refrigeration cycle Rb to the low-temperature side expansion device 6 via the secondary-side flow path 4b of the cascade heat exchanger 4 ( (Shown by a thick line in the figure) is referred to as a low temperature side high pressure section 8.

  Furthermore, a part of the low-temperature side refrigerant pipe Pb from the discharge part a of the low-temperature side compressor 5 to the cascade heat exchanger 4 in the low-temperature side high-pressure part 8 is particularly high-temperature side constituting the high-temperature side refrigeration cycle Ra. A heat exchanging portion (heat exchanging means) 8a is formed that extends to the compressor 1 and exchanges heat between the refrigerant of the low temperature side high pressure portion 8 and the high temperature side compressor 1.

The specific shape of the heat exchange part 8a is as shown in FIG.
As shown in FIG. 2, the low temperature side refrigerant | coolant piping is wound by the outer surface lower part of the airtight case 10 which comprises the high temperature side compressor 1, and it is set as the heat exchange part 8a.

Therefore, the high-pressure and high-temperature low-temperature refrigerant guided from the discharge part a of the low-temperature side compressor 5 exchanges heat with the high-temperature side compressor 1 in the heat exchange part 8a of the low-temperature side high-pressure part 8 to dissipate heat. Is transmitted to the sealed case 10.
As a result, the heat of the low-temperature side refrigerant can be transmitted to the lubricating oil collected inside through the sealed case 10 of the high-temperature side compressor 1.

  As shown in FIG. 3, an annular low temperature side refrigerant pipe inserted into the inside from the bottom of the sealed case 10 constituting the high temperature side compressor 1 is defined as a heat exchanging portion 8 a. An electric compressor main body 13 including an electric motor unit 11 and a compression mechanism unit 12 is accommodated in the sealed case 10, and the compression mechanism unit 12 is immersed in lubricating oil collected at the inner bottom of the sealed case 10.

  In this case, the heat exchange unit 8a is immersed in the lubricating oil without contacting the compression mechanism unit 12. Accordingly, the heat of the low-temperature side refrigerant is directly exchanged with the lubricating oil collected in the high-temperature side compressor 1 to directly transfer the heat of the low-temperature side refrigerant to the lubricating oil.

  As shown in FIG. 1 again, one end of the hot water pipe H is connected to a water supply source, a hot water storage tank or a suction side of a condensate side (return side) buffer tank, and the other end is connected to a hot water storage tank, a hot water tap or an outlet. It is connected to a water side (use side) buffer tank (all not shown).

  In the middle part of the hot water pipe H, a pump 15 for transporting water and a secondary flow path 2b piped in the water / refrigerant heat exchanger 2 are provided. Therefore, the water or hot water led to the hot water pipe H exchanges heat with the refrigerant led to the primary channel 2a in the secondary channel 2b of the water / refrigerant heat exchanger.

  The control unit S includes a temperature sensor and a pressure sensor (not shown, the same applies hereinafter) provided on the discharge part a side of the high temperature side compressor 1 and the low temperature side compressor 5, a temperature sensor provided on the suction part b side, and A detection signal from the pressure sensor is received every predetermined time.

  Further, the water / refrigerant heat exchanger 2 in the hot water pipe H receives detection signals from a water temperature sensor and a flow rate sensor provided on the inlet side and outlet side of the secondary channel 2b every predetermined time. Detection signals are also received from a temperature sensor provided in the cascade heat exchanger 4 and a temperature sensor provided in the air heat exchanger 7.

  Further, upon receiving an operation / stop instruction signal from a remote controller (remote controller), the operating frequencies of the high temperature side compressor 1 and the low temperature side compressor 5 are set and controlled. The detection signals received from the sensors and the remote controller are calculated and compared with a stored reference value, and the opening / closing and the throttle amount of the high temperature side expansion device 3 and the low temperature side expansion device 6 are controlled. And the control mentioned later is made.

  The control unit S, which is the dual refrigeration cycle apparatus R configured as described above and receives an instruction to start the refrigeration cycle operation (heating operation mode), includes the high temperature side compressor 1 of the high temperature side refrigeration cycle Ra and the low temperature side. The low temperature side compressor 5 of the refrigeration cycle Rb is driven and controlled to circulate the refrigerant as will be described later.

In the high temperature side refrigeration cycle Ra, the refrigerant compressed and discharged by the high temperature side compressor 1 is used as follows:-primary side flow path 2a of water / refrigerant heat exchanger 2-high temperature side expansion device 3-cascade heat exchanger 4 Primary side flow path 4a-high temperature side compressor 1- in this order and circulated.
Therefore, the primary side flow path 2a of the water / refrigerant heat exchanger 2 acts as a high temperature side condenser, and the primary side flow path 4a of the cascade heat exchanger 4 acts as a high temperature side evaporator.

  In the low-temperature side refrigeration cycle Rb, the refrigerant compressed and discharged by the low-temperature side compressor 5 is divided into: a secondary side flow path 4b of the cascade heat exchanger 4, a low-temperature side expansion device 6 and an air heat exchanger 7 It is guided in the order of the side compressor 5- and circulated.

  Therefore, the secondary side flow path 4b of the cascade heat exchanger 4 acts as a low temperature side condenser, and the air heat exchanger 7 acts as a low temperature side evaporator. In the cascade heat exchanger 4, the refrigerant condenses in the secondary flow path 4b on the low temperature side refrigeration cycle Rb side to release the condensation heat, and the refrigerant condenses in the primary flow path 4a on the high temperature side refrigeration cycle Ra side. Evaporates while absorbing heat.

  The difference between the refrigerant evaporating temperature in the air heat exchanger 7 and the refrigerant condensing temperature in the water / refrigerant heat exchanger 2 is large in the two-way refrigeration cycle apparatus R, and a high compression ratio is obtained. The water or hot water led to the hot water pipe H is condensed in the high temperature side refrigeration cycle Ra in the secondary side flow path 2b of the water / refrigerant heat exchanger 2, and the primary side flow path 2a of the water / refrigerant heat exchanger 2. It absorbs the high-temperature condensation heat and efficiently raises the temperature.

  In the secondary side flow path 2b of the water / refrigerant heat exchanger 2, the water or hot water led from the water supply source, the hot water storage tank or the condensate side (return side) buffer tank is changed to hot water, and the water / refrigerant heat It is led from the exchanger 2 to the hot water storage tank or the buffer tank on the outgoing side (use side) and circulates. Alternatively, the hot water is directly supplied from the water / refrigerant heat exchanger 2 to the hot water tap.

Next, the state at the time of activation will be described in more detail.
At the time of start-up, the low temperature side compressor 5 is driven and controlled, and the low temperature side refrigerant compressed and heated here is discharged to the low temperature side high pressure portion 8 and led to the heat exchange portion 8 a extended to the high temperature side compressor 1. It is burned.

  In the heat exchange unit 8 a shown in FIG. 2, the heat of the low-temperature side refrigerant is transmitted to the sealed case 10 from being wound around the lower part of the outer surface of the sealed case 10 constituting the high-temperature side compressor 1. This heat is transferred to the lubricating oil collected at the bottom of the sealed case 10 and raises the lubricating oil temperature.

  The heat exchanging portion 8a shown in FIG. 3 is placed on the bottom of the hermetically sealed case 10 of the high temperature side compressor 1 and immersed in the lubricating oil collected here, so that the heat of the low temperature side refrigerant is directly applied to the lubricating oil. Is transmitted to increase the lubricant temperature.

  2 and 3, the temperature of the lubricating oil collected at the bottom of the sealed case 10 of the high-temperature side compressor 1 rises rapidly due to the heat of the low-temperature side refrigerant guided to the heat exchange unit 8a. To do.

  In a state where the temperature of the lubricating oil before starting the high temperature side compressor 1 is low, the high temperature side refrigerant is dissolved in the lubricating oil, the lubricating oil is diluted, and the viscosity is low. As it is, the rotation speed of the high-temperature side compressor 1 cannot be increased, and the state where the motor efficiency is poor continues for a long time. The temperature of the water or the hot water led through the hot water pipe H by the water / refrigerant heat exchanger 2 cannot be quickly raised to a predetermined temperature, resulting in an inefficient state.

  However, as described above, the low temperature side refrigerant compressed and heated at the time of start-up is adopted by adopting the configuration in which the low temperature side refrigerant guided from the low temperature side compressor 5 to the low temperature side high pressure section 8 is guided to the heat exchange section 8a. Is transferred to the lubricating oil of the high-temperature compressor 1 through the heat exchanging portion 8a, and the lubricating oil temperature is quickly raised.

  The lubricating oil is quickly diluted with the high-temperature side refrigerant and has a high viscosity. Lubricating oil having a sufficient viscosity is supplied to each sliding portion of the high-temperature side compressor 1, the rotational speed can be quickly increased, and stable operation can be made in a short time while ensuring reliability.

  In particular, the heat exchanging portion 8a having a simple configuration in which only a part of the low temperature side high pressure portion 8 is extended to the high temperature side compressor 1 is provided without providing a dedicated component for heating the high temperature side compressor 1. Therefore, the desired effect can be obtained and the influence on the cost is negligible.

  Further, if the stable operation state is continued for a long time, each sliding component constituting the compression mechanism unit 12 of the high temperature side compressor 1 is overheated, and the motor efficiency and reliability tend to be lowered. Generally, during stable operation, it is known that the temperature of the low-temperature side refrigerant led to the low-temperature side high-pressure unit 8 is lower than the lubricating oil temperature of the high-temperature side compressor 1.

  Therefore, by configuring as described above, the heat exchanging portion 8a cools the high temperature side compressor 1, thereby improving the motor efficiency and suppressing the overheating of the sliding portion, thereby improving the motor efficiency and reliability. Improvements can be made.

  In the two-stage refrigeration cycle apparatus N configured as described above, the high temperature side compressor 1 and the low temperature side compressor 5 may be started simultaneously, but here, after starting the low temperature side compressor 5, first, The high temperature side compressor 1 is controlled to start according to the conditions.

  Actually, the low temperature side compressor 5 is started and the internal temperature is measured. The high temperature side compressor 1 measures the internal temperature while stopped. By providing the heat exchanging portion 8a of the low temperature side high pressure portion 8, the internal temperature of the high temperature side compressor 1 exceeds the predetermined temperature when a predetermined time elapses. If this is detected, the control part S will control to start the high temperature side compressor 1 for the first time.

  In the dual refrigeration cycle apparatus having a normal configuration in which the low temperature side high pressure unit 8 does not have the heat exchange unit 8a, when the low temperature side compressor constituting the low temperature side refrigeration cycle is started first, the primary side of the cascade heat exchanger The high temperature side refrigerant guided through the flow path absorbs the condensation heat of the low temperature side refrigerant guided through the secondary side flow path and evaporates.

  Therefore, the liquid back amount can be reduced in a state where the high temperature side compressor constituting the high temperature side refrigeration cycle is started. However, at the time of start-up in the high temperature side refrigeration cycle, the temperature of the high temperature side refrigerant does not rise and only the pressure rises, so the amount of the high temperature side refrigerant dissolved in the lubricating oil increases, and the lubricating oil viscosity decreases further. Diluted.

  On the other hand, in the dual refrigeration cycle apparatus N configured as described above, the low temperature side led to the low temperature side high pressure unit 8 by starting the low temperature side compressor 5 constituting the low temperature side refrigeration cycle Rb first. The refrigerant transfers heat to the lubricating oil of the high temperature side compressor 1 in the heat exchange section 8a, and raises this temperature. While the dilution of the lubricating oil can be eliminated quickly and the viscosity can be kept high, the liquid back can be reduced without any trouble.

It should be noted that the start timing of the high temperature side compressor 1 at this time is, for example, after confirming with an image sensor or the like that the oil level of the lubricating oil collected inside has decreased from the motor unit 11.
That is, since the high-temperature side refrigerant is dissolved in the lubricating oil collected in the high-temperature side compressor 1, the lubricating oil surface may rise to the electric motor unit 11 including the stator and the rotor.

  As described above, the heat exchanging portion 8a of the low temperature side high pressure portion 8 heats the high temperature side compressor 1 to reduce the amount of refrigerant melted in the lubricating oil. The high temperature side compressor 1 is started after confirming the state in which the lubricating oil level is lowered and lower than the lower end of the motor unit 11 and is not immersed. Therefore, even when lubricating oil having a low volume resistivity is used, the electric insulation of the electric motor unit 11 can be ensured.

  In the two-stage refrigeration cycle apparatus N configured as described above, the lubricating oil sealed in the high temperature side compressor 1 constituting the high temperature side refrigeration cycle Ra is incompatible with or difficult to phase with respect to the high temperature side refrigerant. It is recommended to use a soluble material. And after evaporating the high temperature side refrigerant | coolant in the high temperature side compressor 1 in the heat exchange part 8a, the high temperature side compressor 1 is started.

  That is, in the high temperature side refrigeration cycle Ra, in addition to the high condensation pressure, the difference between the condensation temperature and the lubricating oil temperature tends to be small. When a lubricating oil that is compatible with the high-temperature side refrigerant is used, the viscosity is lowered due to dilution of the lubricating oil, and the reliability is deteriorated.

  As a countermeasure, it is preferable to use an incompatible or hardly compatible lubricating oil. In this case, the liquid refrigerant and the lubricating oil are separated into two phases at the time of stagnation start-up, and the liquid refrigerant having a high specific gravity is sealed in the sealed case 10. It accumulates at the bottom. If the high temperature side compressor 1 is started in this state, the liquid refrigerant is supplied to the sliding portion by the oil pump provided at the lower end portion of the compression mechanism portion 12, and there is a risk that the lubricity is lacking and damage is caused. There is.

  In the case of the two-stage refrigeration cycle apparatus N configured as described above, the liquid refrigerant accumulated in the high-temperature side compressor 1 is heated and evaporated by the heat exchange unit 8a of the low-temperature side high-pressure unit 8, and then the high-temperature side compression is performed. The machine 1 is started. Since the liquid refrigerant is prevented from being supplied to the sliding portion and the viscosity of the lubricating oil is kept high, the reliability can be improved.

  In the two-stage refrigeration cycle apparatus N configured as described above, the heat exchange unit 8a is provided in the low temperature side refrigerant pipe Pb between the low temperature side compressor 5 and the cascade heat exchanger 4. In other words, the low-temperature side refrigerant pipe Pb constituting the low-temperature side high-pressure part 8 between the cascade heat exchanger 4 and the low-temperature side expansion device 6 is not provided with the heat exchange part 8a.

  That is, the high-temperature low-temperature side refrigerant compressed and discharged by the low-temperature side compressor 5 is directly guided to the heat exchanging portion 8a, and heat exchange is performed with the high-temperature side compressor 1 before starting. Thereafter, the low-temperature side refrigerant is guided to the cascade heat exchanger 4 for heat exchange. Since the lubricating oil of the high temperature side compressor 1 is heated with the higher temperature low temperature side refrigerant before heat exchange in the cascade heat exchanger 4, the heating effect is further enhanced.

  Further, if the stable operation continues for a long time, the low-temperature side refrigerant draws heat from the high-temperature side compressor 1 in the heat exchanging portion 8a. In this state, heat is exchanged in the secondary flow path 4b of the cascade heat exchanger 4, so that the amount of heat increases and the capacity can be expanded.

  FIG. 4 is a configuration diagram of the refrigeration cycle of the binary refrigeration cycle apparatus Na according to the second embodiment. Except for a low-temperature side high-pressure unit 80 described later, the other components are the same as those described above with reference to FIG.

  In the low temperature side refrigeration cycle Rb, the low temperature side high pressure section 80 is partially extended to the high temperature side compressor 1 to extend to the first piping 8Pa that becomes the heat exchange section 8a and the high temperature side compressor 1. And a second pipe line 8Pb that directly communicates from the low temperature side compressor 5 to the secondary side flow path 4b of the cascade heat exchanger 4.

  In addition, in the 1st piping path 8Pa, the opening-closing valve 20 as a switching means is provided in the inlet side of the heat exchange part 8a, and the non-return valve 21 is provided in the exit side of the heat exchange part 8a. If the on-off valve 20 is closed, as indicated by a one-dot chain line arrow in the figure, the low-temperature side refrigerant discharged from the low-temperature side compressor 5 does not enter the first pipe line 8Pa, and the second pipe line 8Pb. Only guided by.

  If the on-off valve 20 is opened, most of the low-temperature side refrigerant is guided to the first pipe line 8Pa and exchanges heat with the high-temperature side compressor 1 at the heat exchanging portion 8a as shown by the dotted arrow in the figure. A part of the low-temperature side refrigerant is guided to the second pipe line 8Pb.

  The controller S controls the opening of the on-off valve 20 at the time of start-up and guides most of the low-temperature side refrigerant to the first piping line 8Pa. Heat is transferred to the high temperature side compressor 1 in the heat exchanging portion 8a, and the viscosity of the lubricating oil collected here is increased to prevent dilution by the refrigerant. From this, it can shift to stable operation at an early stage.

  In the state where the stable operation is continued, the temperature of the low-temperature side high-pressure portion 80 of the low-temperature side refrigeration cycle Rb becomes lower than the temperature of the high-temperature side compressor 1 of the high-temperature side refrigeration cycle Ra, and the high-temperature side compressor 1 is cooled.

  Further, during stable operation, the temperature of the lubricating oil collected in the high temperature side compressor 1 matches the temperature of the water / refrigerant heat exchanger 2 constituting the high temperature side condenser, or the lubricating oil temperature is higher than the condensation temperature. May be lower. In this state, the refrigerant in the sealed case 10 of the high-temperature side compressor 1 condenses and dissolves in the lubricating oil, and the lubricating oil is diluted to lower the viscosity and deteriorate the lubricity, resulting in poor reliability.

  Therefore, when this is detected, the controller S closes the on-off valve 20 and guides the low-temperature side refrigerant to the second pipe line 8Pb. The low temperature side refrigerant is not led to the heat exchanging portion 8a, but is all led to the second pipe line 8Pb. That is, the low-temperature side refrigerant is led directly from the low-temperature side compressor 5 to the cascade heat exchanger 4 through the second piping line 8Pb.

Heat exchange between the low-temperature side high-pressure unit 80 and the high-temperature side compressor 1 is eliminated, and the temperature drop of the lubricating oil in the high-temperature side compressor 1 can be avoided. Therefore, it becomes possible to suppress the dilution of the lubricating oil during stable operation, and it is possible to keep the lubricating oil viscosity high and improve the reliability.
Furthermore, in the low temperature side refrigeration cycle Rb, since there is no heat loss in the heat exchanging portion 8a, the performance of the refrigeration cycle can be improved.

  FIG. 5 is a configuration diagram of the refrigeration cycle of the binary refrigeration cycle apparatus Nb for explaining the third embodiment. Here, the difference from the two-way refrigeration cycle apparatus Na of FIG. 4 is that a three-way valve 22 is provided as a switching means at the branch position of the first piping path 8Pa and the second piping path 8Pb.

  With such a configuration, the low-temperature side refrigerant flowing through the low-temperature side high-pressure unit 80 is completely guided to the first piping line 8Pa as indicated by a broken line arrow in the figure by switching the three-way valve 22, or Is guided to one of the second piping lines 8Pb as indicated by a one-dot chain arrow.

  In this binary refrigeration cycle apparatus Nb, a first temperature sensor (first temperature detection means) that detects the temperature t1 of the water / refrigerant heat exchanger (high temperature side condenser) 2 constituting the high temperature side refrigeration cycle Ra. ) 25 and a second temperature sensor (second temperature detecting means) 26 for detecting the temperature t2 of the lubricating oil collected in the high temperature side compressor 1.

During operation, the detected temperature signals of the temperature sensors 25 and 26 are sent to the control unit S, and are compared and calculated as detected temperatures.
The first temperature sensor 25 detects t1 and the second temperature sensor 26 detects t2 and is compared and calculated by the control unit S. When t1 + α <t2, the low temperature circulating to the low temperature side refrigeration cycle Rb The three-way valve 22 is switched and controlled so as to guide the side refrigerant to the first pipe line 8Pa.

Here, α is a margin that the refrigerant in the high temperature side compressor 1 does not condense and liquefy with respect to the temperature t1 of the high temperature side condenser 2, and is selected from 0 to 10 ° C.
Therefore, the lubricating oil collected in the high temperature side compressor 1 is cooled, and it is possible to prevent a decrease in reliability due to overheating of the sliding portion, a decrease in motor efficiency, and the like.

  Further, during the stable operation, when t1 + α (α: 0 to 10 ° C.)> T2, the three-way valve 22 is switched and controlled so that the refrigerant circulating in the low temperature side refrigeration cycle Rb is guided to the second pipe line 8Pb. Therefore, heat exchange between the lubricating oil collected in the high temperature side compressor 1 and the heat exchanging portion 8a is eliminated, and dilution of the lubricating oil with the refrigerant is suppressed.

  In either case, the control unit S controls the switching timing of the first and second piping paths 8Pa and 8Pb by detecting the temperature of the first and second temperature sensors 16 and 17, so that the above-described effects can be stably obtained. Will be.

  As shown in FIG. 2, the second temperature sensor 26 described above has an outer surface of the outlet portion of the heat exchanging portion (refrigerant pipe) 8a wound around the lower portion of the outer surface of the sealed case 10 constituting the high temperature side compressor 1. You may attach to.

  For example, compared with mounting the second temperature sensor inside the high temperature side compressor 1, the man-hour for taking out the signal line from the temperature sensor and the cost of parts can be reduced, and the number of leak points is reduced and the cost is low. Therefore, a highly reliable refrigeration cycle can be provided.

In the binary refrigeration cycle apparatuses N, Na, and Nb configured as described above, the high temperature side refrigerant used in the high temperature side refrigeration cycle Ra is C ₃ H _m F _n (where m and n are 1 or more and 5 or less. A single refrigerant composed of a refrigerant having an integer and a relationship of m + n = 6) and having one double bond in the molecular structure, or a mixed refrigerant containing the refrigerant is used.

  The refrigerant has a low GWP (global warming potential) and has excellent characteristics as a refrigerant for a refrigeration cycle, but has a characteristic of being easily decomposed at high temperatures. Even if it shifts to the stable operation state from the time of startup and continues for a long time, the high temperature side compressor 1 is cooled by adopting the above-described configuration, and therefore, high temperature decomposition of the high temperature side refrigerant used here can be prevented.

Examples of single refrigerants include:
(1) HFO-1234yf refrigerant (chemical _formula, CF 3 -CF = _CH 2)
(2) HFO-1234ze refrigerant (chemical formula is CF ₃ —CH═CHF)
Examples of the mixed refrigerant include the following.
A mixed refrigerant of any one of the above (1) or (2) and the following refrigerant.
HFC refrigerant (for example, HFC-32, HFC-134a), methane, ethane, propane, propene, butane, isobutane, pentane, 2-methylbutane, cyclopentane, dimethyl ether, carbon dioxide, helium.

Examples of the low-temperature side refrigerant include the following.
(1) Same as high temperature side refrigerant
(2) HFC refrigerant (HFC-410A etc.)
(3) CO ₂
(4) HC refrigerant
Incidentally, the high-temperature side refrigerant, the C ₃ H _m F without such limited to the refrigerant represented by _n. For example, HFC-134a, which is an HFC refrigerant, may be used as the high temperature side refrigerant, and HFC-410A, etc. may be used as the low temperature side refrigerant.

  Note that the refrigeration cycle configuration diagrams of FIGS. 1, 4, and 5 show only the minimum necessary parts, but it is not necessary to be limited to this, for example, a refrigerant receiver, an accumulator, a gas-liquid separator, other piping, etc. May be added. Moreover, when operating by a defrost reverse cycle, although a heat exchange means becomes a low temperature side refrigerant | coolant low pressure part temporarily, there is no trouble.

  As mentioned above, although this embodiment was described, the above-mentioned embodiment is shown as an example and does not intend limiting the range of embodiment. The novel embodiment can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... High temperature side compressor, 2 ... Water / refrigerant heat exchanger (high temperature side condenser), 3 ... High temperature side expansion apparatus, 4 ... Cascade heat exchanger, Pa ... High temperature side refrigerant | coolant piping, Ra ... High temperature side refrigerating cycle, DESCRIPTION OF SYMBOLS 5 ... Low temperature side compressor, 6 ... Low temperature side expansion apparatus, 7 ... Air heat exchanger (low temperature side evaporator), Pb ... Low temperature side refrigerant | coolant piping, Rb ... Low temperature side refrigerating cycle, K ... Housing | casing, N, Na, Nb: binary refrigeration cycle apparatus, 8, 80: low temperature side high pressure section, 8a: heat exchange section (heat exchange means), S: control section, 8Pa: first piping path, 8Pb: second piping path, 25 ... 1st temperature sensor (1st temperature detection means), 26 ... 2nd temperature detection sensor (2nd temperature detection means), 20 ... On-off valve (switching means), 22 ... Three-way valve (switching means).

Claims (6)

High temperature side compressor, high temperature side condenser, high temperature side expansion device, cascade heat exchanger, high temperature side refrigeration cycle communicating with refrigerant piping, low temperature side compressor, cascade heat exchanger, low temperature side expansion device, low temperature A low-temperature side refrigeration cycle communicating with the side evaporator via a refrigerant pipe is mounted in the same housing, and the high-temperature side refrigerant led to the high-temperature side refrigeration cycle and the low-temperature side led to the low-temperature side refrigeration cycle A dual refrigeration cycle apparatus for exchanging heat with a refrigerant in the cascade heat exchanger,
The refrigerant pipe from the low temperature side compressor of the low temperature side refrigeration cycle to the low temperature side expansion device via the cascade heat exchanger is a low temperature side high pressure section,
The low temperature side high pressure part is provided with heat exchange means for extending heat to the high temperature side compressor extending to the high temperature side compressor constituting the high temperature side refrigeration cycle. Dual refrigeration cycle equipment. The dual refrigeration cycle apparatus according to claim 1, wherein the high temperature side compressor of the high temperature side refrigeration cycle is controlled to start after the low temperature side compressor of the low temperature side refrigeration cycle is started. . The dual refrigeration cycle apparatus according to claim 1, wherein the heat exchanging means of the low temperature side high pressure section is provided in the refrigerant pipe communicating the low temperature side compressor and the cascade heat exchanger. The low temperature side high pressure section extends from the low temperature side compressor to the cascade heat exchanger without extending to the first high temperature side compressor and the first piping line that becomes the heat exchange means and extends to the high temperature side compressor. The dual refrigeration cycle apparatus according to claim 1, further comprising a second pipe line that communicates directly. First temperature detection means for detecting the temperature t1 of the high temperature side condenser constituting the high temperature side refrigeration cycle, and second temperature detection for detecting the temperature t2 of the lubricating oil collected in the high temperature side compressor. And a refrigerant circulating in the low temperature side refrigeration cycle based on the temperature detected by the first temperature detecting means and the temperature detected by the second temperature detecting means. 5. The dual refrigeration cycle apparatus according to claim 4, further comprising switching means for switching so as to guide to the pipe line. The refrigerant used in the high temperature side refrigeration cycle is represented by C ₃ H _m F _n (where m and n are integers of 1 or less and 5 and the relationship of m + n = 6 is established), and in the molecular structure 6. The dual refrigeration cycle apparatus according to claim 1, wherein the dual refrigeration cycle apparatus is a single refrigerant or a mixed refrigerant composed of a refrigerant having one double bond.

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