Refrigerant cycle system with expansion energy recovery

Abstract
In a refrigerant cycle system, refrigerant compressed in a first compressor is cooled and condensed in a radiator, and refrigerant from the radiator branches into main-flow refrigerant and supplementary-flow refrigerant. The main-flow refrigerant is decompressed in an expansion unit while expansion energy of the main-flow refrigerant is converted to mechanical energy. Thus, the enthalpy of the main-flow refrigerant is reduced along an isentropic curve. Therefore, even when the pressure within the evaporator increases, refrigerating effect is prevented from being greatly reduced in the refrigerant cycle system. Further, refrigerant flowing into the radiator is compressed using the converted mechanical energy. Thus, coefficient of performance of the refrigerant cycle system is improved.
Description




This application is related to and claims priority from Japanese Patent Applications No. Hei. 11-68871 filed on Mar. 15, 1999 and No. Hei. 11-354817 filed on Dec. 14, 1999, the contents of which are hereby incorporated by reference.




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a vapor-compression type refrigerant cycle system in which expansion energy in an expansion unit is recovered. The present invention is suitably applied to a refrigerant cycle system in which refrigerant such as ethylene, ethane, nitrogen oxide, or carbon dioxide is used so that pressure of refrigerant discharged from a compressor exceeds critical pressure.




2. Description of Related Art




In a conventional vapor-compression type refrigerant cycle, after compressed refrigerant is cooled and is press-reduced, low-pressure refrigerant is evaporated in an evaporator so that refrigerating effect is obtained. However, in the conventional refrigerant cycle, the refrigerating effect is determined based on an enthalpy difference of refrigerant between an inlet side and an outlet side of the evaporator. Therefore, when temperature within the evaporator increases and pressure within the evaporator (i.e., pressure at a refrigerant inlet of the evaporator) increases, the enthalpy difference of refrigerant between the inlet side and the outlet side of the evaporator becomes smaller, and the refrigerating effect of the refrigerant cycle decreases.




SUMMARY OF THE INVENTION




In view of the foregoing problems, it is an object of the present invention to provide a refrigerant cycle system which prevents refrigerating effect from being greatly decreased even when pressure within an evaporator is increased.




According to an aspect of the present invention, a refrigerant cycle system includes a radiator for cooling a compressed refrigerant, an inner heat exchanger in which refrigerant from the radiator branches into first-flow refrigerant and second-flow refrigerant and the second-flow refrigerant is decompressed to perform a heat exchange between the first-flow refrigerant and the decompressed second-flow refrigerant, an expansion unit for decompressing and expanding the first-flow refrigerant having been heat-exchanged with the second-flow refrigerant, an expansion-energy recovering unit for converting expansion energy during a refrigerant expansion in the expansion unit to mechanical energy, and an evaporator for evaporating refrigerant from the expansion unit. The expansion-energy recovering unit is disposed to compress refrigerant flowing into the radiator using the mechanical energy. Thus, an enthalpy difference between a refrigerant inlet side and a refrigerant outlet side of the evaporator is increased by the conversion energy from the expansion energy to the mechanical energy. Therefore, even when the pressure within the evaporator increases, refrigerating effect is prevented from being greatly reduced. Further, because refrigerant flowing into the radiator is compressed using the converted mechanical energy, a compression operation amount is reduced in the while refrigerant cycle system, and coefficient of performance is improved relative to the compression operation amount.




According to an another aspect of the present invention, an expansion unit for decompressing and expanding refrigerant discharged from the radiator is disposed to recover expansion energy during a refrigerant expansion, and a control unit controls a relation amount relative to operation of the expansion unit to control a pressure of high-pressure side refrigerant having been compressed by the compressor and before being decompressed by the expansion unit. Because the refrigerant cycle system operates while the expansion energy is recovered, actual consumption power in the refrigerant cycle system is reduced, and coefficient of performance of the refrigerant cycle system is improved. Therefore, even when the compression operation amount of a compressor increases for preventing the refrigerating effect from reducing when temperature within the evaporator increases, actual consumption power of the compressor is prevented from increasing. Accordingly, even when the pressure within the evaporator increases, the refrigerant cycle system prevents the refrigerating effect from being greatly decreased.




For example, the relation amount relative to the operation of the expansion unit is an energy amount recovered during a refrigerant expansion of the expansion unit, is a refrigerant amount flowing through the expansion unit, or a driving force which is necessary for driving the expansion unit.




Preferably, the control unit controls the pressure of the high-pressure side refrigerant to become a target pressure determined based on a refrigerant temperature at a refrigerant outlet of the radiator. Therefore, the refrigerating effect is further improved in the refrigerant cycle system.











BRIEF DESCRIPTION OF THE DRAWINGS




Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings, in which:





FIG. 1

is a schematic view showing a refrigerant cycle system on a mollier diagram (p-h);





FIG. 2

is a mollier diagram of carbon dioxide according to the first embodiment;





FIG. 3

is a mollier diagram of flon according to the first embodiment;





FIG. 4

is a mollier diagram of a comparison example of the first embodiment;





FIG. 5

is a schematic view showing an energy-recovering unit of a refrigerant cycle system according to a second preferred embodiment of the present invention;





FIG. 6

is a schematic view of a refrigerant cycle system according to a third preferred embodiment of the present invention;





FIG. 7

is a sectional view showing an integrated structure of an expansion unit and a generator according to the third embodiment;





FIG. 8

is a control circuit of the generator according to the third embodiment;





FIG. 9

is a flow diagram showing a control operation of the refrigerant cycle system according to the third embodiment;





FIG. 10

is a mollier diagram of carbon dioxide according to the third embodiment;





FIG. 11

is a sectional view showing an integrated structure of an expansion unit and a generator according to a fourth preferred embodiment of the present invention;





FIG. 12

is a sectional view showing an integrated structure of an expansion unit and a compressor according to a fifth preferred embodiment of the present invention;





FIG. 13

is a schematic view of a refrigerant cycle system according to the fifth embodiment;





FIG. 14

is a flow diagram showing a control operation of the refrigerant cycle system according to the fifth embodiment;





FIG. 15

is a schematic view of a refrigerant cycle system according to a sixth preferred embodiment of the present invention;





FIG. 16

is a schematic view of a refrigerant cycle system according to a seventh preferred embodiment of the present invention;





FIG. 17

is a schematic view of a refrigerant cycle system according to an eighth preferred embodiment of the present invention;





FIG. 18

is a sectional view showing an integrated structure of an expansion unit and a compressor according to the eighth embodiment of the present invention;





FIG. 19

is a sectional view showing an integrated structure of an expansion unit and a compressor according to a ninth preferred embodiment of the present invention;





FIG. 20

is an enlarged view showing a CVT of the integrated structure of the expansion unit and the compressor according to the ninth embodiment;





FIG. 21

is a sectional view of an expansion unit according to a tenth preferred embodiment of the present invention; and





FIGS. 22A

,


22


B,


22


C are schematic views each showing a refrigerant cycle system according to a modification of the present invention.











DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS




Preferred embodiments of the present invention will be described hereinafter with reference to the accompanying drawings.




A first preferred embodiment of the present invention will be now described with reference to

FIGS. 1-4

. In the first embodiment, the present invention is applied to a super-critical refrigerant cycle for a vehicle in which carbon dioxide is used as refrigerant, for example.




In

FIG. 1

, a first compressor


100


for sucking and compressing refrigerant (e.g., carbon dioxide) is driven by a driving unit (not shown) such as a vehicle engine, and gas refrigerant discharged from the first compressor


100


is cooled in a radiator (i.e., gas cooler)


110


. An inner heat-exchanging unit


120


indicated by the chain line in

FIG. 1

includes a branching point


121


at which refrigerant from the radiator


110


branches into main-flow refrigerant directly flowing into a heat exchanger


123


, and supplementary-flow refrigerant flowing into the heat exchanger


123


after passing through a throttle (pressure-reducing unit)


122


. Therefore, in the heat exchanger


123


, the main-flow refrigerant and the supplementary-flow refrigerant are heat exchanged.




The main-flow refrigerant cooled by the supplementary-flow refrigerant in the heat exchanger


123


is decompressed and expanded in an expansion unit


130


. In a second compressor


140


, expansion energy of the main-flow refrigerant expanded in the expansion unit


130


is converted into mechanical energy, and the supplementary-flow refrigerant from the heat exchanger


123


is compressed by using the converted mechanical energy. Therefore, the second compressor


140


is also used as an expansion-energy recovering unit. The compressed supplementary-flow refrigerant is discharged from the second compressor


140


to a refrigerant inlet side of the radiator


110


.




On the other hand, refrigerant discharged from the expansion unit


130


is evaporated in an evaporator


150


to provide refrigerating effect. In the first embodiment, because carbon dioxide is used as refrigerant, the pressure of refrigerant discharged from the first compressor


100


is need to exceed the critical pressure of carbon dioxide for increasing the refrigerating effect.




According to the first embodiment of the present invention, the expansion unit


130


decompresses the main-flow refrigerant while the expansion energy of the main-flow refrigerant is converted into the mechanical energy. Therefore, enthalpy of the main-flow refrigerant flowing from the heat exchanger


123


is decreased while the phase of the main-flow refrigerant is transformed along the isentropic curve “c-d” in FIG.


2


. In

FIG. 2

, the pressure of carbon dioxide is set so that Ph/Pi is 15/6 Mpa. Further, in

FIG. 2

, CP indicates the critical point of mollier diagram.




Thus, it is compared with a refrigerant cycle shown in

FIG. 4

where an adiabatic expansion is simply performed during a decompression operation of refrigerant, an enthalpy difference of refrigerant between an inlet side and an outlet side of the evaporator


150


is increased by expansion operation Δiexp (expansion loss). Further, the second compressor


140


operates by the expansion operation Δiexp, a part of compression operation amount of the first compressor


100


is recovered in the refrigerant cycle system. Thus, in the whole refrigerant cycle system of the first embodiment, the compression operation amount is reduced, and coefficient of performance (COP) relative to the compression operation amount is improved. Accordingly, according to the first embodiment of the present invention, even when an inner pressure of the evaporator


150


is increased, the refrigerating effect is prevented from being greatly decreased, and coefficient of performance (COP) of the refrigerant cycle system is improved.




Further, because the main-flow refrigerant is cooled in the heat exchanger


123


by the supplementary-flow refrigerant having passed through the throttle


122


, enthalpy of refrigerant at the inlet side of the evaporator


150


is decreased, and the enthalpy difference of refrigerant between the inlet side and the outlet side of the evaporator


150


is made larger. Thus, in the refrigerant cycle system of the first embodiment, the refrigerating effect is increased.




In the above-described first embodiment, the carbon dioxide is used as refrigerant. However, flon (HFC


134




a


) may be used as refrigerant. In this case, as shown in

FIG. 3

, enthalpy of the main-flow refrigerant flowing from the heat exchanger


123


is decreased while the phase of the main-flow refrigerant is transformed along the isentropic curve “c-d” in FIG.


3


. In

FIG. 3

, the pressure of flon is set so that Ph/Pi is 22/0.6 Mpa. Even when flon is used as refrigerant circulating in the refrigerant cycle system, the coefficient of performance in the refrigerant cycle system is improved due to the expansion operation Δiexp.




In the above-described first embodiment, the supplementary-flow refrigerant is compressed in the second compressor


140


by using the converted mechanical energy, and is introduced into the radiator


110


. However, the converted mechanical energy may be used for the first compressor


100


, or the other components of the refrigerant cycle system.




A second preferred embodiment of the present invention will be now described with reference to FIG.


5


. In the second embodiment, the inner heat-exchanging unit


120


, the expansion unit


130


and the second compressor


140


described in the above-described first embodiment are integrated to form an integrated member so that the number of components in a refrigerant cycle system is decreased. In the second embodiment, the integrated member is indicated as an energy-recovering unit


200


.




Next, the energy-recovering unit


200


is now described. As shown in

FIG. 5

, within an approximately cylindrical housing


210


, a cylindrical mechanical chamber


240


is formed. A scroll-type energy conversion unit


220


for converting the expansion energy (heat energy) of refrigerant to the mechanical energy (rotation energy) and a scroll compression unit


230


are accommodated in the mechanical chamber


240


. The scroll compression unit


230


are operated to compress the supplementary-flow refrigerant by the rotation energy obtained from the energy conversion unit


220


.




The main-flow refrigerant flows into the energy conversion unit


220


through a main-flow passage


250


formed into a cylindrical shape around the mechanical chamber


240


. On the other hand, the supplementary-flow refrigerant is sucked into the compression unit


230


through a supplementary-flow passage


260


which formed into a cylindrical shape outside the main-flow passage


250


. Further, a flow direction of main-flow refrigerant in the main-flow passage


250


is set to be opposite to a flow direction of supplementary-flow refrigerant in the supplementary-flow passage


260


, so that the main-flow refrigerant and the supplementary-flow refrigerant are heat-exchanged while passing through both the passages


250


,


260


.




Further, when the main-flow refrigerant flows into the energy conversion unit


220


from the main-flow passage


250


, the pressure of the main-flow refrigerant is reduced while a scroll-type turbine (not shown) is rotated by the expansion energy (heat energy). Therefore, the main-flow refrigerant within the energy conversion unit


220


is changed along the isentropic curve. Further, as shown in

FIG. 2

, the main-flow refrigerant having been phase-changed in the energy conversion unit


220


is introduced into the evaporator


150


(see FIG.


1


), and the supplementary-flow refrigerant from the compression unit


230


is introduced into the radiator


110


(see FIG.


1


). In the second embodiment, the other portions are similar to those in the above-described first embodiment.




A third preferred embodiment of the present invention will be described with reference to

FIGS. 6-10

. In the above-described first and second embodiments of the present invention, refrigerant from the radiator


110


branches into the main-flow refrigerant and the supplementary-flow refrigerant. However, in the third embodiment, as shown in

FIG. 6

, refrigerant flowing from the radiator


110


does not branch. Specifically, refrigerant from the radiator


110


flows into the expansion valve


130


so that the expansion energy of refrigerant is converted to the mechanical energy (rotation energy) to be recovered. The recovered mechanical energy is supplied to a generator


300


to generate electrical power. In the third embodiment, the expansion unit


130


is a scroll type as shown in FIG.


7


.

FIG. 7

shows an integrated structure of the expansion unit


130


and the generator


300


. As shown in

FIG. 7

, a rotation shaft


131


of the expansion unit


130


is directly connected to a rotor shaft


301


of the generator


300


.




In the third embodiment and the following embodiments of the present invention, because the first compressor


100


driven by the vehicle engine is only used, the first compressor


100


is referred to as “a compressor


100


”.




Refrigerant flowing from the evaporator


150


is separated in an accumulator (i.e., gas-liquid separating unit)


160


into gas refrigerant and liquid refrigerant. Gas refrigerant separated in the accumulator


160


flows into the compressor


100


, and liquid refrigerant is stored in the accumulator


160


as a surplus refrigerant within the refrigerant cycle system.




Electrical voltage (exciting current) applied to the generator


300


is controlled by an electronic control unit (ECU)


400


which controls the operation of the expansion unit


130


. Signals from a pressure sensor (i.e., pressure detecting unit)


401


for detecting pressure of refrigerant at the outlet side of the radiator


110


and from a temperature sensor (i.e., temperature detecting unit)


402


for detecting temperature of refrigerant at the outlet side of the radiator


110


are input into the ECU


400


. The ECU


400


controls the electrical voltage applied to the generator


303


based on the input signals from the sensors


401


,


402


in accordance with a pre-set program.




Here, an integrated schematic structure of the expansion unit


130


and the generator


300


will be now described. The expansion unit


130


includes a housing


132


. The rotation shaft


131


is rotatably held in the housing


132


through a bearing


132




a


. A crank portion


131




a


is formed in the rotation shaft


131


at a longitudinal end opposite to the generator


300


to be offset from a rotation center axis. A movable scroll


133


is rotatably assembled to the crank portion


131




a


of the rotation shaft


131


through a bearing


131




b


. The movable scroll


133


includes an approximately circular end plate portion


133




a


, and a scroll lap portion


133




b


protruding from the end plate portion


133




a


to a side opposite to the rotation shaft


131


.




A stable scroll


134


includes a scroll lap portion


134




a


engaged with the scroll lap portion


133




b


of the movable scroll


133


, and an end plate portion


134




b


. The end plate portion


134




b


of the stable scroll


134


and the housing


132


define a space where the movable scroll


133


is rotated. The stable scroll


134


and the housing


132


are air-tightly connected by a fastening unit such as a bolt (not shown).




A rotation of the movable scroll


133


around the crank portion


131




a


is prevented by a rotation prevention member


135


. In the third embodiment, the rotation prevention member


135


is constructed by a pin


135




a


and a recess portion


135




b.






Refrigerant from the radiator


110


flows into the expansion unit


130


from a refrigerant inlet


136


. Refrigerant is introduced from the refrigerant inlet


136


into an operation chamber defined by the movable and stable scrolls


133


,


134


. At this time, because the movable scroll


133


is rotated so that the volume of the operation chamber becomes larger due to the refrigerant pressure within the operation chamber, expansion energy of high-pressure refrigerant in the operation chamber is converted into rotation energy (mechanical energy) for rotating the rotation shaft


131


and the movable scroll


133


. Further, the volume of the operation chamber increases while a scroll center moves to an outer side. Therefore, refrigerant moved to a scroll outer side within the operation chamber is decompressed, and the decompressed refrigerant flows from a refrigerant outlet


137


provided in the stable scroll


134


toward the evaporator


150


. Refrigerant and lubrication oil within the housing


132


is prevented from being leaked from a clearance between the housing


132


and the rotation shaft


131


by a shaft seal member attached between the housing


132


and the rotation shaft


131


.




On the other hand, the generator


300


includes a housing


302


. The rotor shaft


301


is disposed in the housing


302


to be rotatable through a bearing


302




a


. A rotor


303


integrally rotated with the rotor shaft


301


includes a pair of rotor cores


303




a


made of ferromagnetic material, and a rotor coil


303




b


inserted between the rotor cores


303




a.






Exciting electrical current is supplied to the rotor coil


303




b


of the rotor


303


through a brush


304




a


and a slip ring


304




b


. In the third embodiment, exciting electrical current is controlled, so that electrical power generated in the generator


300


is controlled and the pressure of high-pressure side refrigerant in the refrigerant cycle system is controlled. Here, the high-pressure side refrigerant is the refrigerant between a discharge side of the compressor


100


and an inlet side of a decompressing unit such as the expansion unit


130


. Therefore, in the third embodiment, refrigerant at the outlet side of the radiator


110


is the high-pressure side refrigerant.




A stator


305


is fixed to the housing


302


. The stator


305


includes a stator core


305




a


made of a ferromagnetic material, and a stator coil wound around the stator core


305




a


. Since the rotor


303


rotates in an excited state, induced electromotive force induced in the stator coil


305




b


of the stator


305


is output as the generated electrical power.





FIG. 8

shows a control circuit


310


of the generator


300


according to the third embodiment. An exciting current is applied to the rotor coil


303




b


in the control circuit


310


, after the control circuit


310


receives the exciting current control signal from the ECU


400


.




Next, operation and characteristics of the refrigerant cycle system according to the third embodiment will be now described.

FIG. 9

shows a control program of the ECU


400


. When a start switch (not shown) of a refrigerant cycle system is turned on, a refrigerant temperature RT at the outlet side of the radiator


110


, detected by the temperature sensor


402


, is input into the ECU


400


, at step S


100


. Next, at step S


110


, a target refrigerant pressure TRP at the outlet side of the radiator


110


is calculated based on the refrigerant temperature RT detected by the temperature sensor


402


.




The target refrigerant pressure TRP is determined based on the relationship between the refrigerant pressure and the refrigerant temperature, indicated by the suitable control line ηmax in FIG.


10


. In

FIG. 10

, the suitable control line ηmax shows the relationship between the refrigerant temperature at the outlet side of the radiator


110


and a refrigerant pressure at the outlet side of the radiator


110


, where the coefficient of performance becomes maximum in the refrigerant cycle system.




Next, at step


120


in

FIG. 9

, a refrigerant pressure RP at the outlet side of the radiator


110


is detected by the pressure sensor


401


, and is input into the ECU


400


. Next, at step S


130


, it is determined whether or not the refrigerant pressure RP at the outlet of the radiator


110


is equal to the target refrigerant pressure TRP. When the refrigerant pressure RP is different from the target refrigerant pressure TRP, the exciting current is controlled so that the refrigerant pressure RP at the outlet side of the radiator


110


becomes equal to the target refrigerant pressure TRP.




Specifically, when the refrigerant pressure RP at the outlet side of the radiator


110


is smaller than the target refrigerant pressure TRP at step S


130


, the exciting current supplied to the rotor coil


303




b


of the rotor


303


is increased at step S


140


so that magnetic force induced in the rotor


303


is increased. Therefore, electrical power generated from the stator coil


305




b


is increased. Thus, a necessary driving force for rotating and driving the generator


300


(rotor


303


), that is, a necessary driving force for driving the expansion unit


130


is increased. Accordingly, load applied to the compressor


100


becomes larger, the pressure of high-pressure side refrigerant (i.e., the refrigerant pressure at the outlet side of the radiator


110


) is increased, and the refrigerant amount flowing into the expansion unit


130


is decreased.




On the other hand, when refrigerant pressure RP at the outlet side of the radiator


110


is larger than the target refrigerant pressure TRP at step S


130


in

FIG. 9

, the exciting current supplied to the rotor coil


303




b


of the rotor


303


is decreased at step S


150


so that magnetic force induced in the rotor


303


is decreased. Therefore, electrical power generated from the stator coil


305




b


is decreased. Thus, a necessary driving force for rotating and driving the generator


300


(rotor


303


), that is, a necessary driving force for driving the expansion unit


130


is decreased. Accordingly, load applied to the compressor


100


becomes smaller, the pressure of high-pressure side refrigerant (i.e., the refrigerant pressure at the outlet side of the radiator


110


) is decreased, and the refrigerant amount flowing into the expansion unit


130


is increased.




Further, when refrigerant pressure RP at the outlet side of the radiator


110


is equal to the target refrigerant pressure TRP at step S


130


, the present condition is maintained at step S


160


. That is, at step S


160


, the present exciting current supplied to the rotor coil


303




b


of the rotor


303


is maintained.




As described above, in the third embodiment of the present invention, among the power supplying to the compressor


100


, the expanding energy generated during a refrigerant decompression is recovered while the refrigerant cycle system operates. Therefore, an actual consumption power consumed in the refrigerant cycle system is reduced.




Thus, actual coefficient of performance is improved in the refrigerant cycle system. Therefore, even when the operation amount of the compressor


100


is increased for preventing the refrigerating effect from decreasing when the refrigerant temperature within the evaporator is increased, the actual consumption power of the compressor


100


is prevented from increasing. Accordingly, even when the refrigerant pressure within the evaporator


150


increases, the refrigerating effect is prevented from greatly being decreased.




A fourth preferred embodiment of the present invention will be now described with reference to FIG.


11


. In the above-described third embodiment, only the shaft


131


of the expansion unit


130


and the shaft


301


of the generator


300


are directly connected, while the housing


132


of the expansion unit


130


and the housing


302


of the generator


300


are separately formed. In the fourth embodiment of the present invention, as shown in

FIG. 11

, both the housings


131


,


301


of the expansion unit


130


and the generator


301


are integrally formed.




In the fourth embodiment, because the housings


131


,


302


of the expansion unit


130


and the generator


301


are integrated, a check seal


321


for air-tightly sealing the housing


302


is attached at electrical terminals


320


of the generator


300


. Therefore, in the fourth embodiment, the seal member


138


contacting the shaft


131


described in the third embodiment is unnecessary. Thus, friction loss on the shaft


131


is reduced, and refrigerant leakage from the expansion unit


130


is prevented. In the fourth embodiment, the other portions are similar to those in the above-described third embodiment, and the explanation thereof is omitted.




A fifth preferred embodiment of the present invention will be now described with reference to

FIGS. 12-14

. In the fifth embodiment, as shown in

FIG. 12

, the expansion unit


130


and the compressor


100


are integrated so that the mechanical energy recovered in the expansion unit


130


is directly supplied to the compressor


100


. Further, as shown in

FIG. 13

, in a refrigerant cycle system of the fifth embodiment, a bypass refrigerant passage


170


through which refrigerant flowing from the radiator


110


is directly introduced into the evaporator


150


while bypassing the expansion unit


130


is provided, and an electrical control valve (throttle member)


180


is disposed in the bypass refrigerant passage


170


. An integrated structure of the expansion unit


130


and the compressor


100


(hereinafter, referred to as “expansion unit-integrated compressor” will be described later in detail. In

FIG. 13

, the expansion unit


130


and the compressor


100


are indicated separately. However, actually, the expansion unit


130


and the compressor


100


are integrated as shown in FIG.


12


.




In the expansion unit-integrated compressor of the fifth embodiment, because the expansion unit


130


and the compressor


100


are rotated with the same rotation speed, the refrigerant pressure at the outlet side of the radiator


110


is not controlled by controlling the expansion unit


130


. Therefore, in the fifth embodiment, by controlling an opening degree of the control valve


180


by the ECU


400


, the refrigerant pressure at the outlet side of the radiator


110


is controlled so that the relationship between the refrigerant temperature and the refrigerant pressure becomes the suitable relationship indicated by the suitable control line ηmax in FIG.


10


.




Next, control operation of the control valve


180


will be now described with reference to FIG.


14


. When a start switch (not shown) of the refrigerant cycle system is turned on, the refrigerant temperature RT at the outlet side of the radiator


110


, detected by the temperature sensor


402


, is input into the ECU


400


, at step S


200


. Next, at step S


210


, a target refrigerant pressure TRP at the outlet side of the radiator


110


is calculated based on the refrigerant temperature RT detected by the temperature sensor


402


. The target refrigerant pressure TRP is determined based on the relationship between the refrigerant pressure and the refrigerant temperature, indicated by the suitable control line ηmax in FIG.


10


.




Next, at step


220


in

FIG. 14

, a refrigerant pressure RP at the outlet side of the radiator


110


is detected by the pressure sensor


401


, and is input into the ECU


400


. Next, at step S


230


, it is determined whether or not the refrigerant pressure RP at the outlet of the radiator


110


is equal to the target refrigerant pressure TRP. When the refrigerant pressure RP is different from the target refrigerant pressure TRP, the opening degree of the control valve


180


is controlled so that the refrigerant pressure RP at the outlet side of the radiator


110


becomes equal to the target refrigerant pressure TRP.




Specifically, when the refrigerant pressure RP at the outlet side of the radiator


110


is smaller than the target refrigerant pressure TRP at step S


230


, the opening degree of the control valve


180


is reduced at step S


240


so that the pressure of high-pressure side refrigerant (i.e., the refrigerant pressure at the outlet side of the radiator


110


) is increased.




On the other hand, when refrigerant pressure RP at the outlet side of the radiator


110


is larger than the target refrigerant pressure TRP at step S


230


, the opening degree of the control valve


180


is increased at step S


250


so that the pressure of high-pressure side refrigerant (i.e., the refrigerant pressure at the outlet side of the radiator


110


) is decreased. Further, when refrigerant pressure RP at the outlet side of the radiator


110


is equal to the target refrigerant pressure TRP at step S


230


, the present condition is maintained at step S


260


. That is, at step S


260


, the present opening degree of the control valve


18


is maintained.




Next, the structure of the expansion unit-integrated compressor will be now described with reference to FIG.


12


. In the expansion unit-integrated compressor of the fifth embodiment, the scroll type compressor


100


, an electrical motor Mo for driving the compressor


100


and the expansion unit


130


are integrated. As shown in

FIG. 12

, the shaft of the compressor


100


, the shaft of the electrical motor Mo and the shaft


131


of the expansion unit


130


are constructed by a single shaft


111


. Because the expansion unit


130


and the compressor


100


(electrical motor Mo) are mechanically connected, the rotation speed of the expansion unit


130


becomes equal to that of the compressor


100


. Therefore, it is impossible to independently control only the expansion unit


130


. On the other hand, in the fifth embodiment, rotation energy generated in the electrical motor Mo and the mechanical energy recovered in the expansion unit


130


are supplied to the compressor


100


.




The compressor


100


is a scroll type including a movable scroll


101


and a stable scroll


102


. A discharging valve


103


is disposed so that discharged refrigerant is prevented from reversely flowing into an operation chamber defined by the movable scroll


101


and the stable scroll


102


. Gas refrigerant from the accumulator


160


is sucked from a suction port


104


to be compressed, and compressed gas refrigerant is discharged to the radiator


110


from a discharge port


105


. A crank portion


106


is disposed at a position offset from a rotation center of the shaft


111


to rotate the movable scroll


101


.




Further, the expansion unit


130


is also a scroll type similarly to the above-described third embodiment. Further, the electrical motor Mo is a DC flange-less motor including a rotatable rotor motor Mo


1


and a stator Mo


2


fixed relative to a housing of the expansion unit-integrated compressor.




Thus, according to the fifth embodiment of the present invention, the coefficient of performance of the refrigerant cycle system is improved in the refrigerant cycle system because the mechanical energy recovered from the expansion unit


130


is used for the compression operation of the compressor


100


.




A sixth preferred embodiment of the present invention will be now described with reference to FIG.


15


. The sixth embodiment is a modification of the above-described fifth embodiment. In the above-described fifth embodiment, the control valve


180


is disposed in the refrigerant bypass passage


170


through which refrigerant from the radiator


110


bypasses the expansion unit


130


. However, in the sixth embodiment, the refrigerant bypass passage


170


is not provided, but the control valve


180


is disposed in a refrigerant passage


171


between the radiator


110


and the expansion unit


130


. In

FIG. 15

, the expansion unit


130


and the compressor


100


are separately indicated. However, similarly to the fifth embodiment, both the expansion unit


130


and the compressor


100


are integrated. Further, the operation of the control valve


180


is controlled similarly to the control method described in the fifth embodiment.




A seventh preferred embodiment of the present invention will be now described with reference to FIG.


16


. The seventh embodiment is a modification of the above-described fifth embodiment. In the above-described fifth embodiment, the control valve


180


is disposed in the refrigerant bypass passage


170


through which refrigerant from the radiator


110


bypasses the expansion unit


130


. However, in the seventh embodiment, the refrigerant bypass passage


170


is not provided, but the control valve


180


is disposed in a refrigerant passage


172


between the expansion unit


130


and the evaporator


150


. In

FIG. 16

, the expansion unit


130


and the compressor


100


are separately indicated. However, similarly to the above-described fifth embodiment, both the expansion unit


130


and the compressor


100


are integrated. Further, the operation of the control valve


180


is controlled similarly to the control method described in the above-described fifth embodiment.




An eighth preferred embodiment of the present invention will be now described with reference to

FIGS. 17 and 18

. In the above-described fifth through seventh embodiments, the expansion unit


130


and the compressor


100


are integrated, and the refrigerant pressure at the outlet side of the radiator


110


is controlled by the control valve


180


. However, in the eighth embodiment, the refrigerant pressure at the outlet of the radiator


110


is controlled without using the control valve


18


in the integrated structure of the expansion unit


130


and the compressor


100


.





FIG. 18

is a sectional view showing an expansion unit-integrated compressor according to the eighth embodiment. As shown in

FIG. 18

, the rotor Mo


1


of the electrical motor Mo and the crank portion


106


of the compressor


100


are linearly connected by the single shaft


111


. Further, the expansion unit


130


is connected to the shaft


111


through an electromagnetic coupling unit


500


which transmits a driving force (mechanical energy) by electromagnetic force. Therefore, mechanical energy recovered in the expansion unit


130


is transmitted to the shaft


111


as the driving force through the electromagnetic coupling unit


500


.




The electromagnetic coupling unit


500


includes a rotor


503




a


composed of a pair of rotor cores


501


, and a rotor coil


502


inserted between the rotor cores


501


. In the electromagnetic coupling unit


500


, an approximately cylindrical cylinder


504


is disposed to face the rotor


503


to have a predetermined clearance between an inner peripheral surface of the cylinder


504


and the rotor


503


so that eddy current is generated.




Electrical power is transmitted to the rotor


503


through a slip ring


505


and brush


506


disposed in the shaft


111


. Further, a seal member


508


for air-tightly sealing the housing


132


is provided in an electrode terminal


507


.




Next, control operation of a refrigerant cycle system according to the eighth embodiment will be now described. In the eighth embodiment, similarly to the above-described third embodiment, the necessary driving force (torque) for driving the expansion unit


130


is controlled so that the pressure of the high-pressure side refrigerant (i.e., the pressure at the outlet side of the radiator


110


) is controlled.




Specifically, when the refrigerant pressure at the outlet side of the radiator


110


is smaller than the target pressure, electrical current supplying to the rotor


503


of the electromagnetic coupling unit


500


is increased, and torque to be transmitted to the electromagnetic coupling unit


500


is increased. Thus, driving force (torque) transmitting to the shaft


111


of the electrical motor Mo and the compressor


100


is increased so that a necessary driving force for driving the expansion unit


130


is increased. Therefore, the pressure of high-pressure side refrigerant (i.e., refrigerant pressure at the outlet side of the radiator


110


) is increased, and the refrigerant amount flowing into the expansion unit


130


is decreased.




On the other hand, when the refrigerant pressure at the outlet side of the radiator


110


is larger than the target pressure, the electrical current supplying to the rotor


503


of the electromagnetic coupling unit


500


is decreased, and torque to be transmitted to the electromagnetic coupling unit


500


is decreased. Thus, driving force (torque) transmitting to the shaft


111


of the electrical motor Mo and the compressor


100


is decreased so that a necessary driving force for driving the expansion unit


130


is decreased. Therefore, the pressure of high-pressure side refrigerant (i.e., refrigerant pressure at the outlet side of the radiator


110


) is decreased, and the refrigerant amount flowing into the expansion unit


130


is increased.




Further, when the refrigerant pressure at the outlet side of the radiator


110


is equal to the target pressure, the present electrical current supplying to the rotor


503


of the electromagnetic coupling unit


500


is maintained.




A ninth preferred embodiment of the present invention will be now described with reference to

FIGS. 19 and 20

. In the above-described eighth embodiment of the present invention, the mechanical energy recovered in the expansion valve


130


is transmitted to the shaft


111


through the electromagnetic coupling unit


500


. However, in the ninth embodiment, the mechanical energy recovered in the expansion unit


130


is transmitted to the shaft


111


through a belt-type non-stage transmission unit (hereinafter, referred to as CVT)


600


.




In the CVT


600


, a belt pulley on which a transmission belt such as a V-belt is hung is formed by combining both conical disks. Further, one side conical disk is moved relative to the other side conical disk, so that a recess width of the belt pulley is changed and the CVT


600


is gear-shifted. The CVT


600


includes an input side pulley


601


and an outlet side pulley


607


.





FIG. 20

is an enlarged view of

FIG. 19

, showing the CVT


600


. In the input side pulley


601


, as shown in

FIG. 20

, within conical disks


602


,


603


integrally rotated with the shaft


131


of the expansion unit


130


, the disk


602


at a side of the movable scroll


133




a


is disposed to be movable relative to the shaft


131


in the axial direction of the shaft


131


. Further, a pressure chamber


605


is defined by an approximately cup-like cylinder


604


and a cylindrical piston portion


602




a


formed in the disk


602


at the side of the movable scroll


133




a


. As shown in

FIG. 19

, the refrigerant pressure discharged from the compressor


100


is adjusted by a control valve


606


and is supplied to the pressure chamber


605


, so that the recess width of the inlet side pulley


601


is controlled.




On the other hand, the outlet side pulley


607


includes a conical disk


608


integrally rotated with the shaft


111


, a conical disk


609


integrally rotated with the shaft


111


to be movable in the axial direction of the shaft


111


, and a coil spring


610


having an elastic force for pressing the disk


609


toward the disk


608


. A V-belt


611


is hung on both the pulleys


601


,


607


.




Next, operation of a refrigerant cycle system according to the ninth embodiment will be now described. In the ninth embodiment, similarly to the eighth embodiment, the necessary driving force (torque) for driving the expansion unit


130


is controlled so that the refrigerant pressure at the outlet side of the radiator


110


is controlled.




Specifically, when the refrigerant pressure at the outlet side of the radiator


110


is smaller than the target pressure, the control valve


606


is adjusted so that the pressure inside the pressure chamber


605


is increased to be larger than the pressure outside the pressure chamber


605


. Therefore, the disk


602


of the inlet side pulley


601


moves toward the disk


603


, and the recess width between both the disks


602


,


603


becomes smaller. Thus, an effective pulley radius around which the V-belt


607


is wound becomes larger, and a transmission ratio (i.e., outlet-side pulley rotation speed/input-side pulley rotation speed) of the CVT


600


becomes larger.




Thus, because the necessary driving force for driving the expansion unit


130


becomes larger, the refrigerant pressure at the outlet side of the radiator


110


is increased, and the refrigerant amount flowing into the expansion unit


130


is decreased.




On the other hand, when the refrigerant pressure at the outlet side of the radiator


110


is larger than the target pressure, the control valve


606


is adjusted so that the pressure inside the pressure chamber


605


is decreased to be smaller than the pressure outside the pressure chamber


605


. Therefore, the disk


602


of the inlet side pulley


601


moves away the disk


603


, and the recess width between both the disks


602


,


603


becomes larger. Thus, an effective pulley radius around which the V-belt


607


is wound becomes smaller, and a transmission ratio (i.e., outlet-side pulley rotation speed/input-side pulley rotation speed) becomes smaller.




Thus, because the necessary driving force for driving the expansion unit


130


becomes smaller, the refrigerant pressure at the outlet side of the radiator


110


is decreased, and the refrigerant amount flowing into the expansion unit


130


is increased.




Further, the recess width of the outlet side pulley


607


is determined based on the effective pulley radius determined by the recess width of the inlet side pulley


601


, the tension of the V-belt


611


and the elastic force of the coil spring


610


.




A tenth preferred embodiment of the present invention will be now described with reference to FIG.


21


. In the above-described ninth embodiment, the CVT


600


is disposed in a driving-force transmission path from the expansion unit


130


to the compressor


100


, and a transmission ratio of the CVT


600


is controlled, so that the driving force for driving the compressor


100


, that is, the necessary driving force for driving the expansion unit


130


is controlled. However, in the tenth embodiment, a variable-capacity type expansion unit


130


in which a refrigerant suction amount is changed is used.




In the tenth embodiment, as shown in

FIG. 21

, the variable-capacity type expansion unit


130


includes a cylindrical housing


130




a


, and a low-ring piston


130




b


rotated in the housing


130




a


to be offset from the center of the housing


130


. An operation chamber


130




c


is defined by the low-ring piston


130




b


and the housing


130




a


, and is partitioned by a vane


130




d


into a refrigerant suction side and a refrigerant discharge side. Further, a spring


130




e


is attached to the vane


130




d


so that the vane


130




d


is pressed to the low-ring piston


130




b


. Further, the variable-capacity type expansion unit


130


includes a suction port


130




f


for sucking refrigerant, a valve


130




g


for opening and closing the suction port


130




f


, and a discharge port


130




h


for discharging refrigerant.




When the refrigerant pressure at the outlet side of the radiator


110


is smaller than the target pressure, a closing timing for closing the suction port


130




f


is made earlier. Therefore, the refrigerant amount flowing into the expansion unit


130


is decreased, and the refrigerant pressure at the outlet side of the radiator


110


is increased to be equal to the target pressure.




On the other hand, when the refrigerant pressure at the outlet side of the radiator


110


is larger than the target pressure, the closing timing for closing the suction port


130




f


is made later. Therefore, the refrigerant amount flowing into the expansion unit


130


is increased, and the refrigerant pressure at the outlet side of the radiator


110


is decreased to be equal to the target pressure.




Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.




In the above-described first embodiment, both the compressors


100


,


140


are used. However, after the main-flow refrigerant and the supplementary-flow refrigerant are joined, the joined refrigerant is compressed by a single compressor using the recovered mechanical energy from the expansion unit


130


.




In the above-described second embodiment, the scroll type energy conversion unit


220


and the scroll type compression unit


230


are used. However, the other type energy conversion unit and compressor such as a piston-type energy conversion unit and a piston type compressor may be used.




In the above-described second embodiment, the expansion energy (heat energy) is directly converted to the mechanical energy. However, after the expansion energy is converted to electrical energy, the electrical energy may be converted to the mechanical energy to operate the second compressor


140


. Further, in this case, by controlling the magnetic field of a generator for converting the expansion energy to the electrical energy, a decompression degree of the expansion unit


130


is controlled so that the refrigerant pressure at the outlet side of the radiator


110


is controlled.




Further, instead of the stable throttle


122


, a movable throttle which changes a throttle opening degree in accordance with operation state of the refrigerant cycle system may be used. In this case, the movable throttle is controlled so that the throttle opening degree is increased when the heat load or the circulation refrigerant amount is increased.




In the above-described third through tenth embodiments, the refrigerant temperature at the high-pressure side refrigerant is directly detected. However, a physical amount relative to the refrigerant temperature of the high-pressure side refrigerant, such as the outside air temperature or the temperature of a refrigerant pipe may be used instead of the directly detected refrigerant temperature.




In the above-described fifth through tenth embodiments, the refrigerant capacity discharged from the compressor


100


is fixed. However, a capacity variable compressor which changes the refrigerant capacity discharged from the compressor


100


may be used, so that the necessary driving force (torque) for driving the expansion unit


130


may be controlled and the refrigerant pressure at the outlet side of the radiator


110


may be controlled.




In the above-described ninth embodiment of the present invention, the CVT


600


is used as a transmission unit. However, a toroidal method without using a belt may be used as the transmission unit.




Further, as shown in

FIGS. 22A

,


22


B,


22


C, plural compressors


100


may be provided, and only one compressor


100


may be driven by the energy converted in the expansion unit


130


. In

FIGS. 22A

,


22


B, the plural compressors


100


are disposed in series in a refrigerant cycle system. On the other hand, in

FIG. 22C

, the plural compressors


100


are disposed in parallel in a refrigerant cycle system.




Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.



Claims
  • 1. A refrigerant cycle system comprising:a compressor for compressing refrigerant; a radiator for cooling refrigerant discharged from said compressor, said radiator having therein a pressure higher than the critical pressure of refrigerant; an expansion-energy recovering unit for decompressing and expanding refrigerant discharged from said radiator in a refrigerant expansion, and for converting expansion energy during the refrigerant expansion to mechanical energy to supply the mechanical energy to said compressor, said expansion-energy recovering unit being integrated with said compressor such that said expansion-energy recovering unit and said compressor are rotated with the same rotation speed; an evaporator for evaporating refrigerant decompressed in said expansion-energy recovering unit; a control unit for controlling a parameter relative to operation of said expansion-energy recovering unit to control a pressure of high-pressure side refrigerant having been compressed by said compressor and before being decompressed; a pressure detection unit for detecting the pressure of high-pressure side refrigerant; a temperature detection unit for detecting the temperature of the high-pressure side refrigerant; and a control valve disposed at an upstream side of said expansion-energy recovering unit in a refrigerant flow direction to control the pressure of the high-pressure side refrigerant based on the temperature of the high-pressure side refrigerant detected by the temperature detection unit.
  • 2. The refrigerant cycle system according to claim 1, wherein said parameter controlled by said control unit is an energy amount recovered during the refrigerant expansion of said expansion unit to control the pressure of the high-pressure side refrigerant.
  • 3. The refrigerant cycle system according to claim 1, wherein said parameter controlled by said control unit is a refrigerant amount flowing through said expansion unit to control the pressure of the high-pressure side refrigerant.
  • 4. The refrigerant cycle system according to claim 1, wherein:said expansion unit is a capacity-variable type in which a refrigerant amount sucked therein is variable; and said parameter controlled by said control unit is the refrigerant amount sucked into said expansion unit to control the pressure of the high-pressure side refrigerant.
  • 5. The refrigerant cycle system according to claim 1, wherein said parameter controlled by said control unit is a driving force which is necessary for driving said expansion unit, to control the pressure of the high-pressure side refrigerant.
  • 6. The refrigerant cycle system according to claim 1, wherein said control unit controls the pressure of the high-pressure side refrigerant to become a target pressure determined based on the refrigerant temperature detected by the temperature detection unit.
  • 7. The refrigerant cycle system according to claim 1, wherein:said compressor includes a shaft and a scroll-type compression portion operated by the shaft; and the expansion-energy recovering unit includes a scroll-type expansion portion operated by the same shaft as the compressor.
  • 8. The refrigerant cycle system according to claim 1, wherein said control valve is disposed between said radiator and said expansion-energy recovering unit in the refrigerant flow direction.
  • 9. The refrigerant cycle system according to claim 8, wherein said pressure detection unit and said temperature detection unit are provided between said radiator and said control valve in the refrigerant flow direction.
  • 10. The refrigerant cycle system according to claim 1, wherein control valve is disposed in a refrigerant passage through which refrigerant from said radiator bypasses said expansion-energy recovering unit.
  • 11. A refrigerant cycle system comprising:a compressor for compressing refrigerant; a radiator for cooling refrigerant discharged from said compressor, said radiator having therein a pressure higher than the critical pressure of refrigerant; an expansion-energy recovering unit for decompressing and expanding refrigerant discharged from said radiator in a refrigerant expansion, and for converting expansion energy during the refrigerant expansion to mechanical energy to supply the mechanical energy to said compressor, said expansion-energy recovering unit being integrated with said compressor such that said expansion-energy recovering unit and said compressor are rotated with the same rotation speed; an evaporator for evaporating refrigerant decompressed in said expansion-energy recovering unit, to which refrigerant from said radiator is introduced through a refrigerant passage; a throttle unit for adjusting an opening area of said refrigerant passage, disposed in said refrigerant passage; a pressure detection unit for detecting a pressure of high-pressure side refrigerant discharged from said compressor, said pressure detection unit being disposed at an upstream side of said throttle unit in a refrigerant flow direction; a temperature detection unit for detecting the temperature of the high-pressure side refrigerant; and a control unit which controls an opening degree of said throttle unit to control the pressure of high-pressure side refrigerant based on the temperature of the high-pressure side refrigerant detected by the temperature detection unit.
  • 12. The refrigerant cycle system according to claim 11, wherein said throttle unit is disposed at a refrigerant upstream side from said expansion unit in said refrigerant passage.
  • 13. The refrigerant cycle system according to claim 11, wherein said throttle unit is disposed at a refrigerant downstream side from said expansion unit in said refrigerant passage.
  • 14. The refrigerant cycle system according to claim 11, wherein:said refrigerant passage include a refrigerant bypass passage through which refrigerant flowing from said radiator is directly introduced into said evaporator while bypassing said expansion unit; and said throttle unit is disposed in said refrigerant bypass passage.
  • 15. The refrigerant cycle system according to claim 11, wherein;the temperature detection unit detects the temperature of refrigerant at an outlet of said radiator; and said control unit controls the pressure of the high-pressure side refrigerant to become a target pressure determined based on the refrigerant temperature at the outlet of said radiator.
  • 16. The refrigerant cycle system according to claim 11, wherein:said compressor includes a shaft and a scroll-type compression portion operated by the shaft; and the expansion-energy recovering unit includes a scroll-type expansion portion operated by the same shaft as the compressor.
  • 17. A refrigerant cycle system comprising:a compressor for compressing refrigerant; a radiator for cooling refrigerant discharged from said compressor, said radiator having therein a pressure higher than the critical pressure of refrigerant; an expansion-energy recovering unit for decompressing and expanding refrigerant discharged from said radiator, and for recovering expansion energy during a refrigerant expansion, said expansion-energy recovering unit being disposed to supply the recovered expansion energy to said compressor; an evaporator for evaporating refrigerant decompressed in said expansion-energy recovering unit; a control unit for controlling a driving force for driving said compressor; a pressure detection unit for detecting the pressure of high-pressure side refrigerant; a temperature detection unit for detecting the temperature of the high-pressure side refrigerant; and a control valve disposed at an upstream side of said expansion-energy recovering unit in a refrigerant flow direction to control the pressure of the high-pressure side refrigerant based on the temperature of the high-pressure side refrigerant detected by the temperature detection unit.
  • 18. The refrigerant cycle system according to claim 17, further comprising:a transmission unit disposed in a transmitting path through which the driving force is transmitted from said expansion unit to said compressor, wherein said control unit controls a transmission ratio of said transmission unit to control the driving force for driving said compressor.
  • 19. The refrigerant cycle system according to claim 17, further comprising:an electromagnetic coupling unit for transmitting the driving force from said expansion unit to said compressor by an electromagnetic force, wherein said control unit controls said electromagnetic coupling unit to control the driving force for driving said compressor.
  • 20. The refrigerant cycle system according to claim 17, wherein:said compressor is a capacity-variable type in which a discharged refrigerant amount is variable; said control unit controls the refrigerant amount discharged from said compressor to control the driving force for driving said compressor.
  • 21. The refrigerant cycle system according to claim 17, wherein said expansion unit and said compressor are an integrated member.
  • 22. The refrigerant cycle system according to claim 17, wherein said control unit controls the pressure of the high-pressure side refrigerant to become a target pressure determined based on the refrigerant temperature detected by the temperature detection unit.
  • 23. The refrigerant cycle system according to claim 17, wherein the control valve is disposed between said radiator and said expansion-energy recovering unit in the refrigerant flow direction.
Priority Claims (2)
Number Date Country Kind
11-68871 Mar 1999 JP
11-354817 Dec 1999 JP
CROSS-REFERENCE TO RELATED APPLICATION

This is a division of U.S. patent application Ser. No. 09/524,676, filed Mar. 13, 2000, now U.S. Pat. No. 6,321,564.

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