JP2008121913A - Vapor compression type refrigerating cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor compression type refrigerating cycle capable of improving coefficient of performance (COP) by introducing a refrigerant discharged by a part of compressors to a plurality of radiators. <P>SOLUTION: This refrigerating cycle 1 is provided with a communication pipe 203 for communicating a first pipe 201 and a second pipe 202, and an opening and closing valve 204 for opening and closing a communication passage in the communication pipe 203. A control device 100 stops one of the compressors, operates the other compressor, and opens the opening and closing valve 204, when a discharge rate of the refrigerant of at least one of the first compressor 11 and the second compressor 21 is reduced to a prescribed rate based on a stable operating state of the compressors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vapor compression refrigeration cycle.

As a prior art, there is a vapor compression refrigeration cycle disclosed in Patent Document 1 below. In this Patent Document 1, a first evaporator is arranged on the downstream side of the refrigerant flow of the ejector serving as a refrigerant decompression means and a refrigerant circulation means, and a second evaporator is arranged on the upstream side of the refrigerant flow of the refrigerant suction port of the ejector. A refrigeration cycle is disclosed. Specifically, a throttle mechanism and a second evaporator are provided in a refrigerant branch passage that reaches an ejector refrigerant suction port branched from an upstream portion of the ejector, and air flows between the first evaporator and the second evaporator having different refrigerant evaporation temperatures. A vapor compression refrigeration cycle in which cooling performance (air cooling performance by an evaporator) is improved in parallel in the direction is shown.
JP 2005-308384 A

  In contrast to the above-described prior art refrigeration cycle, the present applicant, in Japanese Patent Application No. 2006-14186, has already been filed, the refrigerant passage is branched downstream of the first evaporator to provide two refrigerant compressors and two heat dissipations. A vapor compression refrigeration cycle with further improved cooling performance by adjusting the flow rate of refrigerant flowing through the first and second evaporators. Yes.

  As a result of continuing intensive studies aimed at further improving the performance of a refrigeration cycle having a plurality of compressors, the present inventors have started operation when some compressors are stopped and the remaining compressors are in operation. It has been found that there is room to improve the coefficient of performance COP, which is the ratio of the cooling capacity to the amount of work applied by the compressor, by adopting a configuration in which the refrigerant discharged from the compressor is introduced into a plurality of radiators. .

  For example, when the cooling capacity of the evaporator becomes excessive due to low outside air temperature or the like, generally, the operating state of the compressor is controlled to be reduced to a predetermined number of revolutions that can perform stable operation, and on / off control is performed. However, since the compressor and the radiator are in an inoperative state at the time of off, the coefficient of performance COP is deteriorated as compared with the case of continuous operation. In such a case, it has been found that the coefficient of performance COP can be improved by continuously operating only some of the compressors and introducing refrigerant discharged from the compressors into a plurality of radiators. It was.

  For example, when some of the compressors are locked, heat is radiated from the refrigerant only in the radiators connected to the remaining operating compressors, the cooling performance in the evaporator is reduced, and the coefficient of performance COP is deteriorated. There is a case. In such a case, it has been found that by introducing refrigerant discharged from an unlocked compressor into a plurality of radiators, it is possible to improve the cooling performance and improve the coefficient of performance COP.

  The present invention has been made in view of the above points, and provides a vapor compression refrigeration cycle capable of improving the coefficient of performance COP by introducing refrigerant discharged from some compressors into a plurality of radiators. The purpose is to do.

In order to achieve the above object, in the invention described in claim 1,
A first compressor (11) for sucking and compressing and discharging refrigerant;
A first radiator (12) for radiating heat of the refrigerant discharged from the first compressor (11);
A first compressor (11) and a first radiator (12) are provided so as to connect to each other, and a refrigerant discharged from the first compressor (11) is introduced into the first radiator (12). 1 pipe (201),
A second compressor (21) for sucking and compressing and discharging the refrigerant;
A second radiator (22) for radiating heat of the refrigerant discharged from the second compressor (21);
A second compressor (21) is provided to connect the second radiator (12), and a refrigerant discharged from the second compressor (21) is introduced into the second radiator (12). 2 pipes (202),
The refrigerant that has been depressurized and evaporated after being radiated by the first radiator (12) and the refrigerant that has been depressurized and evaporated after being radiated by the second radiator (22) are combined into the first compressor (11) and the second compressor ( 21) a vapor compression refrigeration cycle which is distributed and formed to be inhalable,
A communication path forming member (203) that forms a communication path communicating the inside of the first pipe (201) and the inside of the second pipe (202);
Opening and closing means (204) provided on the communication path forming member (203) for opening and closing the communication path,
Of the first compressor (11) and the second compressor (21), when one compressor is stopped and the other compressor is operating, the opening / closing means (204) is opened. .

  According to this, when one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operating, the opening / closing means (204) is opened to open the compressor. The refrigerant discharged from the other compressor can be introduced into both the first radiator (12) and the second radiator (22) through the communication path provided in the communication path forming member (203). Therefore, the coefficient of performance COP can be improved.

  In the invention according to claim 2, when one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operating, the opening and closing is performed. A control means (100) for controlling the opening of the means (204) is provided.

  According to this, when one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operating, the opening / closing means (204) is easily opened. It can be done quickly.

  In the invention according to claim 3, the control means (100) is configured such that the refrigerant discharge amount of at least one of the first compressor (11) and the second compressor (21) is equal to that of the compressor. When the amount is reduced to a predetermined amount based on the stable operation state, one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operated to open and close. The opening control of the means (204) is performed.

  According to this, the first compressor (11) and the second compressor (21) can be controlled without performing on / off control of the compressor in order to prevent at least one of the compressors from entering a state where the compressor cannot be stably operated. While one compressor is stopped and the other compressor is operated, the opening / closing means (204) can be opened. Therefore, both the first radiator (12) and the second radiator (22) are operated by continuously operating the other compressor and using the communication path in which the discharged refrigerant is provided in the communication path forming member (203). Can be introduced. Therefore, the coefficient of performance COP can be improved.

  In the invention according to claim 4, when the control means (100) detects the locked state of one of the first compressor (11) and the second compressor (21), The opening / closing means (204) is controlled to open.

  According to this, when one of the compressors is locked, the refrigerant discharged from the other unlocked compressor is used as a first radiator (using the communication path provided in the communication path forming member (203). 12) and the second radiator (22). Therefore, the coefficient of performance COP can be improved.

Further, as in the invention according to claim 5,
The pressure energy of the refrigerant flowing out from the first radiator (12) is converted into velocity energy to decompress and expand the refrigerant, and the refrigerant is sucked into the interior by the refrigerant flow injected from the nozzle portion (13a). Refrigerant suction port (13b), and a pressure increasing unit that boosts the pressure of the refrigerant by converting velocity energy into pressure energy while mixing the refrigerant injected from nozzle portion (13a) and the refrigerant sucked from refrigerant suction port (13b) An ejector (13) having (13c, 13d);
A first evaporator (14) for evaporating the refrigerant flowing out of the ejector (13);
Decompression means (23) for decompressing and expanding the refrigerant flowing out of the second radiator (22);
A second evaporator (24) that evaporates the refrigerant depressurized by the depressurization means (23) and flows the evaporated refrigerant into the refrigerant suction port (13b);
The refrigerant evaporated in the first evaporator (14) can be distributed to the first compressor (11) and the second compressor (21) to be sucked.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

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

  FIG. 1 is a schematic configuration diagram illustrating a vapor compression refrigeration cycle 1 according to an embodiment. In the present embodiment, an example in which the refrigeration cycle 1 is applied to a vehicle refrigeration cycle apparatus is shown.

  In the refrigeration cycle 1 of the present embodiment, a plurality of compressors (two compressors, a first compressor 11 and a second compressor 21) for sucking and compressing refrigerant are provided, and the first compressor 11 and the second compressor 21 are provided. Is a variable capacity compressor that can adjust the refrigerant discharge capacity by changing the discharge capacity, or an electric compressor that can adjust the refrigerant discharge capacity by adjusting the rotation speed of the electric motor by an inverter circuit (not shown).

  A first radiator 12 is disposed on the refrigerant discharge side of the first compressor 11. The first radiator 12 cools the high-pressure refrigerant by exchanging heat between the high-pressure refrigerant discharged from the first compressor 11 and the outside air (air outside the passenger compartment) blown by the condenser fan (cooling fan) 36.

Here, when a normal chlorofluorocarbon refrigerant is used as the refrigerant of the refrigeration cycle 1, since the high pressure is a subcritical cycle in which the critical pressure is not exceeded, the radiator 12 acts as a condenser for condensing the refrigerant. On the other hand, when a refrigerant whose high pressure exceeds the critical pressure, such as carbon dioxide (CO ₂ ), is used as the refrigerant, the refrigeration cycle 1 becomes a supercritical cycle.

  An ejector 13 is disposed further downstream than the first radiator 12 in the refrigerant flow. The ejector 13 is a decompression means for decompressing the refrigerant, and is also a refrigerant circulation means (momentum transporting pump) that circulates the refrigerant by suction action (convolution action) of the refrigerant flow ejected at high speed (JIS Z 8126 No. 2). (See 1.2.3).

  The ejector 13 is arranged in the same space as the nozzle portion 13a for reducing the passage area of the high-pressure refrigerant flowing from the first radiator 12 to be isentropically decompressed and expanded, and the refrigerant outlet of the nozzle portion 13a. A refrigerant suction port 13b for sucking a gas-phase refrigerant from the second evaporator 24, which will be described later, is provided.

  The nozzle portion 13a of the ejector 13 in the present embodiment is provided with driving means such as a stepping motor for driving a needle valve body and the like, and the nozzle opening degree can be variably adjusted.

  A mixing unit 13c that mixes the high-speed refrigerant flow from the nozzle unit 13a and the suction refrigerant from the refrigerant suction port 13b is provided at the downstream side of the refrigerant flow of the nozzle unit 13a and the refrigerant suction port 13b.

  And the diffuser part 13d is arrange | positioned in the refrigerant | coolant flow downstream of the mixing part 13c. The diffuser portion 13d is formed in a shape that gradually increases the refrigerant passage area, and acts to decelerate the refrigerant flow to increase the refrigerant pressure, that is, to convert the velocity energy of the refrigerant into pressure energy.

  Note that in the ejector 13 of the present embodiment, the mixing portion 13c is also formed in a shape that gradually increases the passage area of the refrigerant, and the configuration composed of the mixing portion 13c and the diffuser portion 13d is a pressure increase in the ejector 13 of the present embodiment. Part.

  A first evaporator 14 is connected to the downstream side of the diffuser portion 13d of the ejector 13, and the refrigerant flow downstream side of the first evaporator 14 is branched at a branch point Z. The first compressor 11 and the second compressor 21 is connected to the suction side.

  The first compressor 11, the first radiator 12, the ejector 13, and the first evaporator 14 are connected in a ring shape by the refrigerant circulation passage 10.

  A refrigerant branch passage 20 is branched from a branch point Z on the refrigerant circulation passage 10 downstream of the first evaporator 14 and upstream of the first compressor 11, and the downstream side of the refrigerant branch passage 20 is disposed at the ejector 13. The refrigerant suction port 13b is connected.

  In the refrigerant branch passage 20, a second compressor 21 is disposed immediately downstream of the branch point Z, and a second radiator 22 is disposed on the refrigerant discharge side of the second compressor 21. The second radiator 22 is arranged in parallel with the first radiator 12, and high-pressure refrigerant discharged from the second compressor 21 and outside air (air outside the vehicle compartment) blown by the condenser fan (cooling fan) 36 described above. The high-pressure refrigerant is cooled by exchanging heat between the two.

  An expansion valve 23, which is a pressure reducing means, is disposed further downstream of the second radiator 22 than the refrigerant flow, and a second evaporator 24 is disposed downstream of the expansion valve 23 in the refrigerant flow. . The expansion valve 23 of the present embodiment is a fixed throttle mechanism (fixed throttle means), and can be specifically configured with a fixed throttle such as an orifice.

  In the present embodiment, the two evaporators 14 and 24 are assembled into a single structure, and the two evaporators 14 and 24 are accommodated in one case 30. Then, air (cooled air) is blown as indicated by an arrow A by a blower (electric blower) 31 common to the air passage configured in the case 30, and this blown air is cooled by the two evaporators 14 and 24. It has become.

  The cool air cooled by the two evaporators 14 and 24 is sent to the common cooling target space 40, whereby the common cooling target space 40 is cooled by the two evaporators 14 and 24.

  Here, of the two evaporators 14 and 24, the first evaporator 14 disposed in the refrigerant circulation passage 10 downstream of the ejector 13 is disposed upstream of the air flow A, and the refrigerant suction port 13b of the ejector 13 is disposed. The second evaporator 24 connected to is disposed downstream of the air flow A.

  Note that when the refrigeration cycle 1 of the present embodiment is applied to a refrigeration cycle apparatus for vehicle air conditioning, the vehicle interior space becomes the cooling target space 40. In addition, when the refrigeration cycle 1 of the present embodiment is applied to a refrigeration vehicle refrigeration cycle apparatus, the space inside the refrigeration refrigerator of the refrigeration vehicle becomes the space to be cooled 40.

  In the refrigerant circulation passage 10 of the present embodiment, the refrigerant discharge port of the first compressor 11 and the refrigerant introduction port of the first radiator 12 are connected by a first pipe 201, and the first compressor 11 is The discharged refrigerant can be introduced into the first radiator 12 through the first pipe 201.

  Further, in the refrigerant branch passage 20, the refrigerant outlet of the second compressor 21 and the refrigerant inlet of the second radiator 22 are connected by the second pipe 202, and the second compressor 21 discharges. The cooled refrigerant can be introduced into the second radiator 22 through the second pipe 202.

  The first pipe 201 and the second pipe 202 are connected by a communication pipe 203, and the communication pipe 203 is provided with an electric opening / closing valve 204 for opening and closing a communication path formed in the communication pipe 203. Yes. When the open / close valve 204 is opened, the first pipe 201 and the second pipe 202 communicate with each other through a communication path formed in the communication pipe 203.

  The communication pipe 203 is a communication path forming member in the present embodiment, and the opening / closing valve 204 is an opening / closing means provided in the communication path forming member.

  1 is a control device for an air conditioner, and the control device 100 is a control means in this embodiment.

  The control device 100 detects the temperature in the space to be cooled 40 (inside air temperature, in particular, the air temperature that flows into the two evaporators 14 and 24 again from within the space to be cooled 40). Nozzles of the first compressor 11, the second compressor 21, and the ejector 13 on the basis of input information such as temperature information from the control unit 40, and set temperature information from the temperature setting means 40 provided on the operation panel (not shown). The unit 13a, the blower 31, the condenser fan 36, the opening / closing valve 204, and the like are controlled to operate.

  Next, based on the said structure, the action | operation of the vapor compression refrigeration cycle 1 of this embodiment is demonstrated.

  FIG. 2 is a flowchart showing a schematic control operation of the control device 100.

  As shown in FIG. 2, the control device 100 first calculates the required cooling capacity (step 110). Specifically, a difference ΔT between the set temperature of the cooling target space 40 and the temperature in the cooling target space 40 detected by the internal air temperature sensor 90 is calculated.

  Next, the total refrigerant flow rate (total refrigerant circulation flow rate) is calculated (step 120). The total refrigerant flow rate is the total flow rate of the refrigerant discharged from the first compressor 11 and the second compressor 21 and flowing through the refrigerant circulation passage 10 and the refrigerant branch passage 20 and corresponds to the refrigerant flow rate flowing through the first evaporator 14.

  The total refrigerant flow rate is calculated by, for example, a method of calculating from a relational expression between a preset cooling condition and a refrigerant flow rate, or a pressure sensor that detects the refrigerant high-pressure side pressure and low-pressure side pressure of the refrigeration cycle 1 is provided. It implements by well-known methods, such as the method of calculating based on the detected value.

  Thereafter, an optimal flow rate ratio mapped in advance with respect to the overall flow rate (the refrigerant flow rate G1 (drive flow rate) flowing through the refrigerant circulation passage 10 and injected from the ejector 13 nozzle portion 13a and the refrigerant branch passage 20 and the ejector 13 refrigerant suction port) The ratio of the refrigerant flow rate G2 (suction flow rate) sucked from 13b is calculated (step 130).

  Next, the optimal refrigerant discharge amount of the first compressor 11 and the second compressor 21 is calculated from the optimal flow rate ratio calculated in step 130. When both the compressors 11 and 21 are variable capacity types, the optimum capacity is calculated, and when both the compressors 11 and 21 are electric compressors, the optimum rotational speed of the electric motor is calculated (step 140). .

  Then, it is determined whether or not the refrigerant discharge amount (capacity or rotational speed) of both the compressors 11 and 21 calculated in step 140 is equal to or larger than a predetermined amount (predetermined capacity or predetermined rotational speed) based on the stable operation state of the compressor. (Step 150). Specifically, the predetermined amount based on the stable operation state of the compressor is predetermined based on the return limit of the lubricating oil that returns to the compressor together with the refrigerant, and is used to ensure the reliability of the compressor. It can be said that the minimum discharge amount (minimum capacity or minimum rotation speed).

  When it is determined in step 150 that both refrigerant discharge amounts of the compressors 11 and 21 are equal to or greater than the predetermined amount (minimum discharge amount), the refrigerant discharge amount (capacity or rotation speed) calculated in step 140 is used. Thus, the first compressor 11 and the second compressor 21 are controlled to operate (step 160). At this time, the on-off valve 204 is controlled to be closed.

  When it is determined in step 150 that at least one of the refrigerant discharge amounts of both the compressors 11 and 21 is less than the predetermined amount (minimum discharge amount), either one of the compressors 11 and 21 is compressed. The machine is stopped, and the other compressor is controlled to operate so that the refrigerant discharge amount is equal to or higher than the predetermined amount (preferably the total refrigerant flow rate), and the open / close valve 204 is controlled to be in the open state (step 170). .

  When step 170 is executed, which of the first compressor 11 and the second compressor 21 is in an operating state is determined based on the operation time of the first compressor 11 and the second by the operation time management by the timer of the control device 100. It is preferable to determine and control so that the operation time of the compressor 21 is substantially equal.

  After either of steps 160 and 170 is executed, the operation of the drive motor of the condenser fan 36 and the drive motor of the blower 31 is finally controlled so that the condenser fan 36 and the blower 31 generate the optimum air volume (step 180). Return to step 110.

  Further, when the control device 100 performs the control shown in FIG. 2, the control device 100 also performs the control shown in the flow in FIG.

  As shown in FIG. 3, the control device 100 first determines whether one of the first compressor 11 and the second compressor 21 is in a locked state (step 210).

  When the compressors 11 and 21 are variable displacement types, the compressor lock detection by the control device 100 is, for example, the compressor rotation speed detected by the lock sensor provided in the compressor and the compressor drive source (for example, This is based on the difference from the rotational speed of an engine (not shown). Moreover, when the compressors 11 and 21 are electric compressors, it carries out based on the inverter electric current value of the inverter circuit which is not shown in figure, for example.

  That is, it can be said that the lock sensor for detecting the rotational speed and the inverter current value detection means are compressor lock detection means. The control device 100 detects the lock state of the compressor based on the detection result of the lock detection means.

  If it is determined in step 210 that neither the first compressor 11 nor the second compressor 21 is in the locked state, normal control whose flow is shown in FIG. 2 is performed (step 220). If it is determined in step 210 that one of the first compressor 11 and the second compressor 21 is in the locked state, the open / close valve 204 is controlled to be opened while controlling the operation of the compressor that is not in the locked state. (Step 230). When either step 220 or 230 is executed, the process returns to step 210.

  According to the control operation of the control device 100 described above, when the first compressor 11 and the second compressor 21 shown in FIG. 1 are operated, the gaseous refrigerant flowing out from the first evaporator 14 is distributed at the branch point Z. The two compressors 11 and 21 are sucked and compressed.

  The high-temperature and high-pressure refrigerant compressed and discharged by the first compressor 11 flows into the first radiator 12. In the first radiator 12, the high-temperature refrigerant is cooled by the outside air. The high-pressure refrigerant that has flowed out of the first radiator 12 flows toward the ejector 13.

  On the other hand, the high-temperature and high-pressure refrigerant compressed and discharged by the second compressor 21 flows into the second radiator 22. In the second radiator 22, the high-temperature refrigerant is cooled by outside air. The high-pressure refrigerant that has flowed out of the second radiator 22 is decompressed by the expansion valve 23 to become a low-pressure refrigerant, and this low-pressure refrigerant flows into the second evaporator 24. In the 2nd evaporator 24, a refrigerant | coolant absorbs heat from the ventilation air which flows outside in the arrow A direction, and evaporates.

  The refrigerant flow flowing out of the first radiator 12 and flowing into the ejector 13 is decompressed and expanded by the nozzle portion 13a whose opening degree is adjusted. Accordingly, the pressure energy of the refrigerant is converted into velocity energy by the nozzle portion 13a, and the refrigerant is ejected from the jet port of the nozzle portion 13a as a high-speed flow. Due to the refrigerant pressure drop at this time, the refrigerant (gas phase refrigerant) after passing through the second evaporator 24 in the branch refrigerant passage 20 is sucked from the refrigerant suction port 13b.

  The refrigerant ejected from the nozzle portion 13a and the refrigerant sucked from the refrigerant suction port 13b are mixed in the mixing portion 13c on the downstream side of the nozzle portion 13a and flow into the diffuser portion 13d. In the diffuser portion 13d, the passage area is enlarged, so that the speed (expansion) energy of the refrigerant is converted into pressure energy, so that the pressure of the refrigerant increases.

  Then, the refrigerant that has flowed out of the diffuser portion 13 d of the ejector 13 flows into the first evaporator 14. The low-temperature low-pressure refrigerant flowing in the first evaporator 14 absorbs heat from the blown air flowing outside in the direction of arrow A and evaporates. The vapor-phase refrigerant after evaporation is diverted at the aforementioned branch point Z and is sucked and compressed again by the first compressor 11 and the second compressor 21.

  Since the refrigerant pressure is boosted in the boosting section of the ejector 13, the refrigerant evaporation pressure (refrigerant evaporation temperature) in the second evaporator 24 is made lower than the refrigerant evaporation pressure (refrigerant evaporation temperature) in the first evaporator 14. Can do.

  And since the 1st evaporator 14 with a high refrigerant | coolant evaporation temperature is arrange | positioned in the upstream with respect to the flow direction A of blowing air, and the 2nd evaporator 24 with a low refrigerant | coolant evaporation temperature is arrange | positioned in the downstream, the 1st It is easy to ensure both the temperature difference between the refrigerant evaporation temperature and the blown air in the evaporator 14 and the temperature difference between the refrigerant evaporation temperature and the blown air in the second evaporator 24.

  For this reason, both the cooling performance of the 1st, 2nd evaporators 14 and 24 can be exhibited effectively. Therefore, the cooling performance for the common cooling target space 40 can be effectively improved by the combination of the first and second evaporators 14 and 24. Further, the suction pressure of the first and second compressors 11 and 21 can be increased by the pressure increasing action in the mixing unit 13c and the diffuser unit 13d, and the driving power of both the compressors 11 and 21 can be reduced.

  The first compressor 11 and the second compressor 21 are each operated so as to discharge the amount of refrigerant determined by the control device 100 under the control of step 160 shown in FIG.

  Therefore, the refrigerant flow rate G1 flowing through the refrigerant circulation passage 10 and injected from the ejector 13 nozzle portion 13a and the refrigerant flow rate G2 flowing through the refrigerant branch passage 20 and sucked from the ejector 13 refrigerant suction port 13b are the optimum flow rates calculated in step 130. It becomes a ratio. The total refrigerant flow rate (the sum of G1 and G2) circulating in the refrigeration cycle 1 is a flow rate corresponding to the cooling capacity calculated in step 120.

  In addition, when the refrigerant discharge amount determined by the control device 100 is less than the minimum discharge amount at which at least one of the first compressor 11 and the second compressor 21 is difficult to continue stable operation, While the compressor is stopped and the other compressor is operated in a state where it can be stably operated, the opening / closing valve 204 is opened.

  Thereby, a part of the refrigerant discharged from the operating compressor of the first compressor 11 and the second compressor 21 flows through the communication passage in the communication pipe 203, and the first radiator 12 and the second compressor 2 Introduced into both radiators 22. Therefore, the refrigerant circulates in both the refrigerant circulation passage 10 and the refrigerant branch passage 20 and exhibits cooling performance in the first evaporator 14 and the second evaporator 24.

  When the control device 100 detects the locked state of either the first compressor 11 or the second compressor 21, the open / close valve 204 is opened while the unlocked compressor is operating. .

  Also in this case, the refrigerant discharged from the operating compressor of the first compressor 11 and the second compressor 21 partly flows through the communication passage in the communication pipe 203, and the first radiator 12 and It is introduced into both of the second radiators 22. Therefore, the refrigerant circulates in both the refrigerant circulation passage 10 and the refrigerant branch passage 20 and exhibits cooling performance in the first evaporator 14 and the second evaporator 24.

  According to the configuration and operation described above, the control device 100 sets the refrigerant discharge amount of at least one of the first compressor 11 and the second compressor 21 to a predetermined amount based on the stable operation state of the compressor. When the number of the first compressor 11 and the second compressor 21 is decreased, one of the first compressor 11 and the second compressor 21 is stopped and the other compressor is operated, so that the opening / closing valve 204 is controlled to be opened.

  For example, when the cooling capacity is excessive at a low outside air temperature (when the inside air temperature is lower than the target set temperature), the calculated control target values of the compressors 11 and 21 are the reliability of the compressor. Compression of one of the first compressor 11 and the second compressor 21 when it is below the lower limit capacity or the lower limit rotational speed at which the minimum discharge amount (lower limit discharge amount, near-lower limit discharge amount) is ensured. The machine is stopped, the other compressor is operated, and the opening / closing valve 204 is controlled to open.

  Therefore, in order to prevent at least one of the compressors from falling into a state where stable operation cannot be continued, one compressor is continuously operated in a state where stable operation is possible without performing on / off control of the compressor, and discharge is performed. The cooled refrigerant can be introduced into both the first radiator 12 and the second radiator 22.

  In such operation control, it is possible to suppress the high-pressure side pressure of the refrigeration cycle, compared to the case where both compressors are operated and on / off controlled, and the discharged refrigerant is introduced into a radiator connected to each compressor. The compressor power can be reduced.

  In addition, when the control device 100 detects the lock of one of the first compressor 11 and the second compressor 21, the control device 100 controls the opening / closing of the opening / closing valve 204.

  Therefore, the refrigerant discharged from the unlocked compressor can be introduced into both the first radiator 12 and the second radiator 22.

  As described above, when one of the first compressor 11 and the second compressor 21 is stopped and the other compressor is operating, the opening / closing valve 204 is controlled to open. The refrigerant discharged from the operating compressor can be introduced into both the first radiator 12 and the second radiator 22 through the communication path in the communication pipe 203. Therefore, it is possible to improve the coefficient of performance COP as compared with the case where the communication passage and the configuration having no means for opening and closing the communication passage are provided.

  Moreover, at the time of control which operates both the compressors 11 and 21, according to the cooling capacity requested | required, the refrigerant | coolant discharge amount of the 1st compressor 11 and the refrigerant | coolant discharge amount of the 2nd compressor 21 are adjusted, and the refrigerating cycle 1 is carried out. The refrigerant flow rate (total refrigerant flow rate G1 + G2) circulating inside and the ratio of the refrigerant flow rate G1 injected from the ejector 13 nozzle portion 13a and the refrigerant flow rate G2 sucked from the ejector 13 refrigerant suction port 13b are controlled. .

  Therefore, the refrigerant flow rate (G1 + G2) flowing through the first evaporator 14 and the refrigerant flow rate (G2) flowing through the second evaporator 24 can be adjusted according to the required cooling capacity, and the cooling performance is further improved. can do.

  Under conditions where the normal cycle heat load is small, the difference between the high and low pressures of the cycle becomes small, and the input of the ejector 13 becomes small. In this case, in the cycle that branches at the upstream portion of the ejector, the flow rate of the refrigerant passing through the second evaporator depends only on the refrigerant suction ability of the ejector, so the input of the ejector decreases → the refrigerant suction capacity of the ejector decreases → second A decrease in the refrigerant flow rate of the evaporator occurs, and it is difficult to ensure the cooling performance of the second evaporator.

  On the other hand, according to the present embodiment, the refrigerant circuit of the refrigeration cycle 1 is branched at the upstream portion of the compressor, and is sucked into the refrigerant passage input to the ejector 13 nozzle portion 13a and the ejector 13 refrigerant suction port 13b. The refrigerant passages are connected in parallel. Then, compressors 11 and 21 are provided in both passages to control the refrigerant discharge amount.

  For this reason, the refrigerant can be supplied to the refrigerant branch passage 20 by utilizing not only the refrigerant suction capability of the ejector 13 but also the refrigerant suction / discharge capability of the compressor 21. Thereby, even if the phenomenon that the input of the ejector 13 decreases and the refrigerant suction capacity of the ejector 13 decreases occurs, the degree of decrease in the refrigerant flow rate on the second evaporator 24 side can be made smaller than the cycle of Patent Document 1. Therefore, it is easy to ensure the cooling performance of the second evaporator 24 even under low heat load conditions.

  In addition, the control device 100 controls the operation of the first compressor 11 and the second compressor 21, thereby allowing the refrigerant flow rate G1 to be injected from the ejector 13 nozzle portion 13a and the refrigerant sucked from the ejector 13 refrigerant suction port 13b. The flow rate G2 can be easily adjusted.

  In the present embodiment, an example in which the vapor compression refrigeration cycle 1 is applied to a refrigeration cycle apparatus for a vehicle has been described. However, the refrigeration cycle to which the present invention is applied is particularly a vehicle for a large vehicle such as a bus having a large vehicle interior space. It is suitable for application to an air conditioner for automobiles.

  As described above, an air conditioner such as a bus has a large air-conditioned space, and thus has conventionally been provided with a plurality of refrigerant compressors and equipped with a number of refrigeration cycles corresponding to the number of compressors. For example, there is an air conditioner equipped with two independent refrigeration cycles having a compressor.

  On the other hand, in the case of an air conditioner that employs the refrigeration cycle 1 of the present embodiment, it is a case where two evaporators are used to demonstrate the cooling capacity using two compressors as in the conventional independent two-system cycle. However, a part of the refrigerant piping system on the low pressure side is used in common, and the piping can be simplified.

(Other embodiments)
In the above embodiment, the ejector nozzle portion 13a is a variable opening (throttle) type and the expansion valve 23 is a fixed throttle type. However, the present invention is not limited to this, and the ejector nozzle portion 13a may be a fixed throttle type. It doesn't matter. Further, an electronic expansion valve may be adopted as the expansion valve 23 so as to be a variable throttle type.

  In the above embodiment, the refrigeration cycle 1 includes the first and second compressors 11 and 21, the first and second radiators 12 and 22, the ejector 13, the expansion valve 23, and the first and second evaporators 14. , 24 are connected by piping, but the components are not limited to these.

  For example, as shown in FIG. 4, when the receivers 51 and 52 and the ejector 13 nozzle portion 13a for separating the refrigerant from the gas and liquid at the downstream of each radiator and storing the excess refrigerant are of the fixed-throttle type, the first evaporator 14 An expansion valve 53 that finely adjusts the refrigerant pressure flowing into the ejector 13 nozzle portion 13a according to the degree of refrigerant superheat flowing out, stores the surplus refrigerant by separating the refrigerant gas and liquid upstream of the compressor, and reduces the amount of oil returned to the compressor At least one of the accumulators 54 and the like for adjustment may be appropriately set as necessary.

  In the above embodiment, the refrigeration cycle 1 is a refrigeration cycle in which the ejector 13 is used and the nozzle portion 13a is used as the pressure reducing means on the refrigerant circulation circuit 10 side. However, the invention is not limited to this. For example, as shown in FIG. 5, the decompression means of the two refrigerant circulation passages 10A and 20A are both expansion valves 131 and 231, and the first compressor 11 and the first radiator 12 of the first refrigerant circulation circuit 10A The first pipe 201 for connecting the second pipe 21 and the second pipe 202 for connecting the second compressor 21 of the second refrigerant circulation circuit 20A and the second radiator 22 are connected by a communication pipe 203, and an opening / closing valve 204 is provided. It may be.

  In such a configuration, the same effect can be obtained by performing the same control as in the above embodiment. In this configuration, as shown in FIG. 5, if the upstream sides of the first compressor 11 and the second compressor 21 are communicated with each other by a communication pipe 205, the refrigerant circulation passages 10A and 20A are joined and branched. There is no need, and the refrigerant can be distributed to the first compressor 11 and the second compressor 21. That is, the present invention can be easily applied to two conventional refrigeration cycles.

  Of course, a piping configuration in which the downstream sides of the first evaporator 14A and the second evaporator 24A shown in FIG. 5 are joined together and branched on the upstream side of the first compressor and the second compressor may be used. The first evaporator 14A and the second evaporator 24A are not limited to those arranged in series with the air flow, but may be arranged in parallel with the air flow.

  In the above-described embodiment and the refrigeration cycle 1A shown in FIG. 5, two compressors are provided, but three or more refrigeration cycles may be provided.

  In the above-described embodiment, the opening / closing means for the communication path provided in the communication pipe 203 serving as the communication path forming member is the opening / closing valve 204. Although the detailed description of the on-off valve 204 is omitted, in the case of the above-described embodiment, a valve (for example, a reversible valve) is difficult to move even if pressure is applied from any direction of the communication path in the closed state. ) Is preferable. However, the opening / closing means is not limited to this type.

  In the closed state, a differential pressure valve type valve that presses the valve body in one direction in the flow path direction of the communication path may be adopted. When a differential pressure valve type opening / closing means is employed, for example, as shown in FIG. 6, a plurality of communication passages (communication piping 203A, 203B) are formed, and a check valve that determines the flow direction in the opening / closing valves 204A, 204B. 206A and 206B may be provided in combination, and the opening and closing valves 204A and 204B may be prevented from opening due to the discharge pressure difference between the compressors 11 and 21 when the opening and closing valves 204A and 204B are closed.

  Further, the open / close valve 204 is a valve that forms an open state and a closed state, but a flow rate control valve type (opening adjustment type) valve may be employed as the open / close means. According to this, even if one compressor is stopped and the other compressor is operating, the ratio of the refrigerant flow rates G1 and G2 can be easily adjusted.

  Moreover, in the said one Embodiment, although the communicating path formation member was the communication piping 203, it is not limited to this. For example, a block body directly attached to the first compressor 11 and the second compressor 21 is used as a communication path forming member, and a communication path that connects the discharge ports of both compressors is formed in the block body. There may be provided an opening / closing means for opening / closing. Even in this case, it can be said that the communication path substantially communicates the first pipe and the second pipe.

  Further, in the above embodiment, the control device 100 performs the control shown in FIG. 3 while performing the control shown in FIG. 2, but may perform only one of the controls.

  Further, in the above-described embodiment, when one of the first compressor 11 and the second compressor 21 is stopped and the other compressor is operating, the control device 100 controls the opening / closing valve 204. The opening control is performed, but the present invention is not limited to this. For example, when one of the first compressor 11 and the second compressor 21 is stopped and the other compressor is operating, the on-off valve may be opened manually.

  In the above-described embodiment, the refrigeration cycle for the vehicle has been described. However, the present invention is not limited to the vehicle and can be applied to a refrigeration cycle for stationary use as well.

In the above embodiment, the type of the refrigerant is not specified. However, the refrigerant may be any one of a supercritical cycle and a subcritical cycle of a vapor compression type such as CFC-based, HC-based alternative CFC, and carbon dioxide (CO ₂ ). It may be applicable.

  Here, chlorofluorocarbon is a general term for organic compounds composed of carbon, fluorine, chlorine, and hydrogen, and is widely used as a refrigerant. Fluorocarbon refrigerants include HCFC (hydro-chloro-fluoro-carbon) refrigerants, HFC (hydro-fluoro-carbon) refrigerants, etc. These are refrigerants called substitute chlorofluorocarbons because they do not destroy the ozone layer. is there.

  The HC (hydrocarbon) refrigerant is a refrigerant substance that contains hydrogen and carbon and exists in nature. Examples of the HC refrigerant include R600a (isobutane) and R290 (propane).

1 is a schematic configuration diagram showing a vapor compression refrigeration cycle 1 in an embodiment to which the present invention is applied. 3 is a flowchart showing a schematic control operation of the control device 100. 5 is a flowchart showing another control operation of the control device 100. It is a schematic block diagram which shows the structural example of the vapor compression type refrigerating cycle in other embodiment. It is a schematic block diagram which shows the structural example of the vapor compression type refrigerating cycle in other embodiment. It is a schematic block diagram which shows the structural example of the principal part of the vapor compression type refrigerating cycle in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 11 1st compressor 12 1st heat radiator 13 Ejector 13a Nozzle part 13b Refrigerant suction port 13c Mixing part (a part of pressure | voltage rise part)
13d Diffuser section (part of booster section)
14 1st evaporator 21 2nd compressor 22 2nd radiator 23 Expansion valve (pressure reduction means)
24 Second evaporator 100 Control device (control means)
201 first pipe 202 second pipe 203 communication pipe (communication path forming member)
204 Open / close valve (open / close means)

Claims (5)

A first compressor (11) for sucking and compressing and discharging refrigerant;
A first radiator (12) for radiating heat of the refrigerant discharged from the first compressor (11);
The first compressor (11) and the first radiator (12) are provided so as to be connected, and the refrigerant discharged from the first compressor (11) is introduced into the first radiator (12). A first pipe (201) for
A second compressor (21) for sucking and compressing and discharging the refrigerant;
A second radiator (22) for radiating heat of the refrigerant discharged from the second compressor (21);
The second compressor (21) and the second radiator (12) are provided so as to be connected, and the refrigerant discharged from the second compressor (21) is introduced into the second radiator (12). A second pipe (202) for
The refrigerant that has been depressurized and evaporated after being radiated by the first radiator (12), and the refrigerant that has been depressurized and evaporated after being radiated by the second radiator (22) are used as the first compressor (11) and the first refrigerant. A vapor compression refrigeration cycle that is distributed to two compressors (21) and configured to be inhalable;
A communication path forming member (203) that forms a communication path that connects the first pipe (201) and the second pipe (202);
Opening and closing means (204) provided on the communication path forming member (203) for opening and closing the communication path,
When one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operating, the opening / closing means (204) is opened. A featured vapor compression refrigeration cycle.   When one of the first compressor (11) and the second compressor (21) is stopped and the other compressor is operating, the opening / closing means (204) is controlled to open. The vapor compression refrigeration cycle according to claim 1, further comprising control means (100).   The control means (100) sets the refrigerant discharge amount of at least one of the first compressor (11) and the second compressor (21) to a predetermined amount based on a stable operation state of the compressor. Of the first compressor (11) and the second compressor (21), one compressor is stopped and the other compressor is operated, and the opening / closing means (204) The vapor compression refrigeration cycle according to claim 2, wherein opening control is performed.   When the control means (100) detects the locked state of one of the first compressor (11) and the second compressor (21), the control means (100) opens the opening / closing means (204). 4. The vapor compression refrigeration cycle according to claim 2, wherein control is performed. A nozzle part (13a) that converts the pressure energy of the refrigerant flowing out of the first radiator (12) into velocity energy to decompress and expand the refrigerant, and the refrigerant is sucked into the interior by the refrigerant flow injected from the nozzle part (13a). The refrigerant suction port (13b) and the refrigerant jetted from the nozzle part (13a) and the refrigerant sucked from the refrigerant suction port (13b) are mixed to convert the velocity energy into pressure energy to thereby change the refrigerant pressure. An ejector (13) having a boosting section (13c, 13d) for boosting;
A first evaporator (14) for evaporating the refrigerant flowing out of the ejector (13);
Decompression means (23) for decompressing and expanding the refrigerant flowing out of the second radiator (22);
A second evaporator (24) for evaporating the refrigerant depressurized by the depressurization means (23) and allowing the evaporated refrigerant to flow into the refrigerant suction port (13b);
The refrigerant evaporated in the first evaporator (14) is distributed to the first compressor (11) and the second compressor (21) so that the refrigerant can be sucked. The vapor compression refrigeration cycle according to any one of the above.

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