Refrigeration cycle device

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2007-268764 filed on Oct. 16, 2007, the contents of which are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a refrigeration cycle device including an ejector and plural evaporators.

BACKGROUND OF THE INVENTION

Conventionally, a refrigeration cycle device including an ejector and plural evaporators is known (e.g., JP-A-2007-24412). The plural evaporators of the refrigeration cycle device includes a first evaporator disposed to evaporate refrigerant downstream of the ejector and coupled to a refrigerant suction side of the compressor, a second evaporator connected to a refrigerant suction port of the ejector, and a third evaporator having a refrigerant outlet connected to the refrigerant suction side of the compressor. The first evaporator and the second evaporator are integrated as an evaporator unit, and the evaporator unit is located to cool a first space to be cooled. In contrast, the third evaporator is located to cool a second space to be cooled.

However, according to experiments by the inventors of the present application, in the refrigeration cycle device with the ejector, the cooling capacity of the third evaporator for cooling the second space to be cooled is lower than the cooling capacity of the evaporator unit for cooling the first space to be cooled. Therefore, it is difficult to improve the cooling capacity of the third evaporator.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the present invention to provide a refrigeration cycle device including an ejector and plural evaporators, in which cooling capacities of the plural evaporators can be effectively improved.

It is another object of the present invention to provide a refrigeration cycle device including an ejector, first and second evaporators located downstream of the ejector in a first refrigerant passage, and a third evaporator located in a second refrigerant passage branched from the first refrigerant passage, in which a pressure-loss generation portion is provided to generate a pressure loss in the first refrigerant passage thereby causing the refrigerant to easily flow into the second refrigerant passage. It is further another object of the present invention to improve a cooling capacity of the third evaporator in the refrigeration cycle device.

According to an aspect of the present invention, a refrigeration cycle device includes a compressor configured to draw and compress refrigerant, a radiator configured to cool high-pressure refrigerant discharged from the compressor, a first branch portion configured to branch the refrigerant flowing from the radiator into first and second streams, first and second refrigerant passages in which the refrigerant of the first stream and the refrigerant of the second stream branched at the first branch portion flow respectively, a join portion configured to join the refrigerant flowing from the first refrigerant passage and the refrigerant flowing from the second refrigerant passage, a second branch portion configured to branch the refrigerant of the first stream in the first refrigerant passage, an ejector located in the first refrigerant passage and having a nozzle portion configured to decompress the refrigerant flowing from the second branch portion in the first refrigerant passage, a first evaporator located in the first refrigerant passage to evaporate the refrigerant flowing out of the ejector, a branch passage through which the refrigerant branched at the second branch portion flows into the refrigerant suction port of the ejector, a first throttle portion provided in the branch passage to decompress the refrigerant flowing into the branch passage from the second branch portion, a second evaporator located in the branch passage to evaporate the refrigerant flowing out of the first throttle portion, a second throttle portion provided in the second refrigerant passage to decompress the refrigerant flowing into the second refrigerant passage from the first branch portion, a third evaporator located in the second refrigerant passage to evaporate the refrigerant flowing out of the second throttle portion, and a pressure-loss generation portion configured to generate a pressure loss in the first refrigerant passage.

Accordingly, it is possible to suitably distribute a flow amount of the refrigerant flowing into the first refrigerant passage and a flow amount of the refrigerant flowing into the second refrigerant passage, thereby improving the cooling capacities of the first to third evaporators. Specifically, because the pressure-loss generation portion is configured to generate the pressure loss in the first refrigerant passage, the refrigerant easily flows into the second refrigerant passage from the first branch portion, thereby increasing the flow amount of the refrigerant flowing into the third evaporator. Thus, the cooling capacity of the third evaporator can be effectively improved in the refrigeration cycle device in which the first refrigerant passage and the second refrigerant passage are joined at the join portion so that the refrigerant pressure (refrigerant temperature) of the third evaporator is equal to the refrigerant pressure (refrigerant temperature) of the first evaporator.

For example, the first evaporator and the second evaporator are located to cool air to be blown into a first space to be cooled, and the third evaporator is located to cool air to be blown into a second space to be cooled. In this case, the second space can be sufficiently cooled to a suitable temperature by using the third evaporator. The first evaporator and the second evaporator may be located in series in a flow direction of air flowing toward the first space to be cooled, and the second evaporator may be located downstream of the first evaporator in the flow direction of air.

The pressure-loss generation portion may be located in the first refrigerant passage at a position from the first branch portion to the nozzle portion, may be located in the first refrigerant passage at a position from the a refrigerant outlet of the ejector to the join portion, may be located in the first refrigerant passage at a position from the a refrigerant outlet of the first evaporator to the join portion, or may be located in the first refrigerant passage to have a throttle mechanism that is configured to decompress the refrigerant in the first refrigerant passage.

The first refrigerant passage may be provided with a passage portion that has a passage cross-section area smaller than a passage cross-section area of the second refrigerant passage. In this case, the pressure-loss generation portion may be constructed of the passage portion in the first refrigerant passage.

Alternatively, the pressure-loss generation portion may be a pressure-loss generation means provided in the first branch portion. In this case, the first branch portion is configured to have the pressure-loss generation means for generating the pressure loss in the first refrigerant passage such than an inflow direction of the refrigerant flowing into the first refrigerant passage from the first branch portion is smaller than an inflow direction of the refrigerant flowing into the second refrigerant passage from the first branch portion, relative to an inflow direction of the refrigerant flowing into the first branch portion.

Alternatively, the pressure-loss generation portion may be a pressure-loss generation means provided in the join portion. In this case, the join portion is configured to have the pressure-loss generation means for generating the pressure loss in the first refrigerant passage such that an inflow direction of the refrigerant flowing into the join portion from the first refrigerant passage is smaller than an inflow direction of the refrigerant flowing into the join portion from the second refrigerant passage, relative to a flowing-out direction of the refrigerant flowing out of the join portion.

Furthermore, in the refrigeration cycle device, the first evaporator and the second evaporator may be integrated to form a single evaporator unit. In this case, the ejector, the branch passage and the first throttle portion may be assembled integrally to the evaporator unit.

In the refrigeration cycle device, a decompression unit separated from the pressure-loss generation portion may be located in the first refrigerant passage to decompress the refrigerant before flowing into the nozzle portion of the ejector. As an example, the pressure-loss generation portion is located in the first refrigerant passage from the decompression unit to an inlet of the nozzle portion of the ejector.

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 refrigerant circuit diagram of a refrigeration cycle device having an ejector and plural evaporators according to a first embodiment of the present invention;

FIG. 2 is a schematic perspective view showing the structure of an integrated unit of the first embodiment;

FIG. 3 is a Mollier diagram showing refrigerant states of a refrigerant cycle in the refrigeration cycle device according to the first embodiment;

FIG. 4 is a graph showing cooling performance of the refrigeration cycle device according to the first embodiment;

FIG. 5 is a refrigerant circuit diagram of a refrigeration cycle device having an ejector and plural evaporators according to a second embodiment of the present invention; and

FIG. 6 is a Mollier diagram showing refrigerant states of a refrigerant cycle in the refrigeration cycle device according to the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A refrigeration cycle device 10 according to a first embodiment of the invention will be described with reference to FIGS. 1 to 4. In the first embodiment, the refrigeration cycle device 10 is typically used for a vehicle air conditioner. In the refrigeration cycle device 10 of the present embodiment, a compressor 11 for drawing and compressing refrigerant is rotatably driven by an engine for vehicle running (not shown) via a pulley, a belt and the like.

As the compressor 11, may be used either a variable displacement compressor for being capable of adjusting a refrigerant discharge capacity by a change in discharge volume, or a fixed displacement compressor for adjusting a refrigerant discharge capacity by changing an operating efficiency of the compressor by intermittent connection of an electromagnetic clutch. When an electric compressor is used as the compressor 11, the compressor 11 can adjust the refrigerant discharge capacity by adjustment of the number of revolutions of an electric motor.

A refrigerant radiator 12 is disposed on the refrigerant discharge side of the compressor 11. The radiator 12 exchanges heat between high-pressure refrigerant discharged from the compressor 11 and outside air (i.e., air outside a vehicle compartment) blown by a cooling fan (not shown) to cool the high-pressure refrigerant.

In the present embodiment, a flon-based refrigerant or a HC-based refrigerant is used as the refrigerant for the refrigeration cycle device 10 to form a vapor-compression subcritical refrigerant cycle in which a refrigerant pressure on the high-pressure side does not exceed the critical pressure of the refrigerant. Thus, the radiator 12 serves as a condenser for cooling and condensing the refrigerant.

A liquid receiver 12a is provided on the refrigerant outlet side of the radiator 12. The liquid receiver 12a has a vertically oriented tank shape to be well known, and serves as a gas-liquid separator for separating the refrigerant flowing out of the radiator 12 into gas and liquid phases to store the excess liquid refrigerant in the refrigerant cycle. The liquid refrigerant is guided to flow from the lower part of the inside of the tank shape at the outlet of the liquid receiver 12a. The liquid receiver 12a can be integrally formed with the radiator 12 or can be formed separately from the radiator 12, in the present embodiment.

The radiator 12 may have the known structure including a first heat exchange portion for condensation disposed on the upstream side of the refrigerant flow, the liquid receiver 12a for receiving the refrigerant introduced from the first heat exchange portion for condensation to separate the refrigerant into gas and liquid phases, and a second heat exchange portion for supercooling of the saturated liquid refrigerant from the liquid receiver 12a. Alternatively, the liquid receiver 12a may be omitted.

A first branch portion 100 is located downstream of the liquid receiver 12a to branch a flow of refrigerant flowing from the liquid receiver 12a into two refrigerant streams. For example, the first branch portion 100 is constructed of a three-way joint having a single refrigerant inlet 100a and two refrigerant outlets 100b, 100c. For example, the refrigeration cycle device 10 is provided with the single refrigerant inlet 100a, the one refrigerant outlet 100b as a first refrigerant outlet, and another refrigerant outlet 100c as a second refrigerant outlet.

The first refrigerant outlet 100b of the first branch portion 100 is coupled to a join portion 110 via a first refrigerant passage 13, and the second refrigerant outlet 100c of the first branch portion 100 is coupled to the join portion 110 via a second refrigerant passage 14. The join portion 110 is located at a refrigerant suction side of the compressor 11 such that the first and second refrigerant streams branched at the first branch portion 100 are joined at the join portion 110. The join portion 110 is a three-way joint including a refrigerant inlet 110a connected to the first refrigerant passage 13, a refrigerant inlet 110b connected to the second refrigerant passage 14, and a refrigerant outlet 110c connected to the refrigerant suction side of the compressor 11.

A first expansion valve 15 is disposed in the first refrigerant passage 13 in which the refrigerant of the first stream branched at the first branch portion 100 flows. The first expansion valve 15 serves as a thermal expansion valve for decompressing the liquid refrigerant from the liquid receiver 12a through the first branch portion 100, and has a temperature sensing portion 15a disposed at a refrigerant downstream side of the first evaporator 18. That is, the temperature sensing portion 15a is disposed at the refrigerant suction side of the compressor 11.

The first expansion valve 15 detects a degree of superheat of the refrigerant on the downstream refrigerant side of the first evaporator 18 based on the temperature and pressure of the refrigerant on the downstream refrigerant side of the first evaporator 18 in the first refrigerant passage 13. The first expansion valve 15 adjusts its valve open degree such that the degree of superheat of refrigerant at the refrigerant outlet side of the first evaporator 18 is a preset predetermined value while a refrigerant flow amount can be adjusted, as being generally known.

Furthermore, as the first expansion valve 15, a mechanical thermal expansion valve or an electrical expansion valve may be used. When the electrical expansion valve is used as the first expansion valve 15, a valve open degree of the first expansion valve 15 is electrically adjusted based on detection signals of a refrigerant temperature sensor and a refrigerant pressure sensor located at a downstream refrigerant side of the first evaporator 18.

A pressure-loss generation mechanism 16 is located in the first refrigerant passage 13 at a downstream refrigerant side of the first expansion valve 15 to generate a pressure loss in the first refrigerant passage 13. For example, the pressure-loss generation mechanism 16 is a throttle portion configured to decompress the refrigerant.

The first expansion valve 15 is located to adjust the super-heat degree of the refrigerant at the refrigerant outlet of the first evaporator 18. In contrast, the pressure-loss generation mechanism 16 is located to generate a pressure loss in the first refrigerant passage 13 in which the refrigerant branched at the first branch portion 100 flows, thereby adjusting a ratio between a flow amount of refrigerant flowing in the first refrigerant passage 13 and a flow amount of refrigerant flowing in the second refrigerant passage 14.

Because the pressure-loss generation mechanism 16 is located in the first refrigerant passage 13, the flow amount of refrigerant flowing into the second refrigerant passage 14 can be increased among the refrigerant streams branched at the first branch portion 100. As the pressure-loss generation mechanism 16, a fixed throttle such as a capillary tube or an orifice or a variable throttle may be used.

An ejector 17 is disposed at an outlet side of the pressure-loss generation mechanism 16. The ejector 17 serves as a decompression means for decompressing the refrigerant, and also as a refrigerant circulation means (kinetic vacuum pump) for circulating the refrigerant by a suction action (an entrainment action) of a refrigerant flow ejected at high velocity.

The ejector 17 includes a nozzle portion 17a that decreases the passage sectional area of the refrigerant having passed through the pressure-loss generation mechanism 16 to decompress and expand the refrigerant in isentropic. The ejector 17 also includes a refrigerant suction port 17b that is arranged in the same space as a refrigerant jet port of the nozzle portion 17a to draw the gas-phase refrigerant from a second evaporator 21 to be described later.

In the ejector 17, a mixing portion 17c is provided on a downstream side of the nozzle portion 17a and the refrigerant suction port 17b in a refrigerant flow, so as to mix the high-velocity refrigerant flow jetted from the nozzle portion 17a with the suction refrigerant drawn from the refrigerant suction port 17b. Furthermore, a diffuser portion 17d serving as a pressure increasing portion is provided in the ejector on a downstream side of the refrigerant flow of the mixing portion 17c. The diffuser portion 17d is formed in the ejector 17 in such a shape to gradually increase the passage sectional area of the refrigerant, and has an effect of reducing the velocity of the refrigerant flow to increase the refrigerant pressure, that is, an effect of converting the velocity energy of the refrigerant to the pressure energy thereof.

The ejector 17 has a shape that extends substantially cylindrically in an elongated manner elongated in a longitudinal direction. The ejector 17 includes a refrigerant flow inlet of the nozzle portion 17a located on one end side thereof in the longitudinal direction (on the left end side thereof shown in FIG. 1), and a refrigerant outlet of the diffuser portion 17d located on the other end side thereof in the longitudinal direction (on the right end side thereof shown in FIG. 1). The refrigerant suction port 17b is disposed between the refrigerant flow inlet and the refrigerant discharge port in the longitudinal direction of the ejector 17 (in the direction from left to right shown in FIG. 1). The refrigerant outlet side of the diffuser portion 17d of the ejector 17 is connected to the first evaporator 18, and the refrigerant outlet side of the first evaporator 18 is connected to the refrigerant inlet 110a of the join portion 110.

A second branch portion 120 is located in the first refrigerant passage 13 to branch the refrigerant at a position between an upstream side of the nozzle portion 17a of the ejector 17 and the outlet side of the pressure-loss generation mechanism 16. A refrigerant branch passage 19 is branched from the second branch portion 120, and is connected to the refrigerant suction port 17b of the ejector 17. The second branch portion 120 is a three-way joint having one refrigerant inlet 120a and two refrigerant outlets 120b, 120c.

A throttle mechanism 20 is located in the refrigerant branch passage 19 to adjust a flow amount of the refrigerant flowing into the second evaporator 21 and to decompress the refrigerant. The throttle mechanism 20 may be a fixed throttle such as a capillary tube. The second evaporator 21 is located in the refrigerant branch passage 19 to evaporate the refrigerant after passing through the throttle mechanism 20. The evaporated refrigerant of the second evaporator 21 is drawn into the ejector 17 from the refrigerant suction port 17b.

In the present embodiment, the ejector 17, the first and second evaporators 18 and 21, the second branch portion 120, the refrigerant branch passage 19 and the throttle mechanism 20 are assembled integrally to form an integrated unit 22. FIG. 2 shows an example of the integrated unit 22.

The two evaporators 18 and 21 are integrated to form a single evaporator structure (evaporator unit 23). A common electric blower 24 blows air (i.e., air to be cooled) in the direction of arrow “X”, so that the blown air is cooled by the two evaporators 18, 21.

The conditioned air cooled by the two evaporators 18, 21 is sent into a common space 25 to be cooled. This leads to cooling of the common space 25 to be cooled by the two evaporators 18, 21. For example, the common space 25 is a front seat area (front space) in a passenger compartment of the vehicle. The first evaporator 18 is positioned at an upstream area in the evaporator unit 23 in an air flow X, and the second evaporator 21 having a refrigerant evaporation pressure (refrigerant evaporation temperature) lower that of the first evaporator 18 is positioned at a downstream area in the evaporator unit 23 in the air flow X. That is, among the two evaporators 18 and 21, the first evaporator 18 connected to the first refrigerant passage 13 on the downstream side of the ejector 17 is disposed on the upstream side (windward side) of the air flow X, and the second evaporator 21 connected to the refrigerant suction port 17b of the ejector 17 is disposed on the downstream side (leeward side) of the air flow X.

Accordingly, both a temperature difference between the refrigerant evaporation temperature of the first evaporator 18 and blown air and a temperature difference between the refrigerant evaporation temperature of the second evaporator 21 and blown air can be sufficiently obtained.

Now, an example of the integrated unit 22 including the two evaporators 18, 21 will be explained with reference to FIG. 2. In the example shown in FIG. 2, the two evaporators 18 and 21 are completely integrated as one evaporator unit 23. Thus, the first evaporator 18 constructs an upstream side portion of the air flow X in the integrated one evaporator unit 23, and the second evaporator 18 constructs a downstream side portion of the air flow X in the integrated one evaporator unit 23.

The first evaporator 18 and the second evaporator 21 have the same basic structure, including heat-exchange core portions 18a and 21a and tanks 18b, 18c, 21b, and 21c positioned on both upper and lower sides of the heat-exchange core portions 18a and 21a.

Each of the heat-exchange core portions 18a, 21a includes a plurality of tubes 26 respectively extending vertically. Between the tubes 26, a passage is formed for allowing a heat-exchanged medium, that is, the air to be cooled in the present embodiment, to pass therethrough.

Fins 27 are disposed between adjacent the tubes 26 in a stack direction of the tubes 26, and can be brazed to the tubes 26. Each of the heat-exchange core portions 18a, 21a is constructed of a stacked structure including the tubes 26 and the fins 27. These tubes 26 and fins 27 are alternately staked in the stack direction (e.g., the left/right direction or lateral direction of the heat-exchange core portions 18a, 21a). In another example, a structure without fins 27 can be employed.

Although FIG. 2 shows only parts of the fins 27, the fins 27 may be formed over the entire areas of the heat-exchange core portions 18a, 21a. The stacked structure including the tubes 26 and the fins 27 is formed over each of the entire areas of the heat-exchange core portions 18a, 21a. The blown air from the electric blower 24 passes through voids of the stacked structure.

The tube 26 defines therein a refrigerant passage, and is constructed of a flat tube having a flat section elongated along the air flow direction X. The fin 27 is a corrugated fin formed by bending a thin plate in a wave-like shape, and is connected to the flat outer surface of the tube 26 to increase an air-side heat transmission area.

The tube 26 of the heat-exchange core portion 18a and the tube 26 of the heat-exchange core portion 21a respectively define the refrigerant passages that are independent from each other. A partition plate 32 is located in the upper tank 18b to partition an inner space of the upper tank 18b into left and right two areas 28, 29 in FIG. 2, and a partition plate 33 is located in the upper tank 21b to partition an inner space of the upper tank 21b into left and right two areas 30, 31 in FIG. 2

Aluminum which is a metal having excellent thermal conductivity and brazing property is suitable as specific material for components of the first and second evaporator 18, 21, such as the tube 26, the fin 27, and the tanks 18b, 18c, 21b and 21c. Each component can be formed using a metal such as the aluminum material, so that all components of the first and second evaporators 18 and 21 can be assembled and connected integrally by brazing.

The first and second evaporators 18, 21 are integrated to form the evaporator unit 23. Next, the ejector 17, the refrigerant branch passage 19, the throttle mechanism 20 and a connection block 34 are assembled integrally to the evaporator unit 23 so as to form the integrated unit 22. The connection block 34 is a member brazed to one side surface portion of the upper tanks 18b, 21b of the first and second evaporators 18, 21, and is configured to construct a single refrigerant inlet 35 and a single refrigerant outlet 36 of the integrated unit 22. Therefore, the integrated unit 22 has a simple pipe connection structure.

The refrigerant inlet 35 provided in the connection block 34 is branched into a main passage 35a extending toward the inlet side of the nozzle portion 17a of the ejector 17, and a branch passage 19 extending toward the inlet side of the throttle mechanism 20 (e.g., capillary tube). In the example of FIG. 2, the second branch portion 120 is provided in the connection block 34 so that the single refrigerant inlet 35 and the single refrigerant outlet 36 are formed in the integrated unit 22. Therefore, the structure of the integrated unit 22 can be made simple.

Next, a refrigerant flow in the integrated unit 22 will be described. The refrigerant decompressed in the pressure-loss generation mechanism 16 flows into the integrated unit 22 from the refrigerant inlet 35 of the connection block 34, and is branched at the second branch portion 120 provided in the connection block 34 into the main passage 35a and the branch passage 19.

The refrigerant of the main passage 35a inside the connection block 34 passes through the nozzle portion 17a, the mixing portion 17c and the diffuser portion 17d of the ejector 17, the right side area 29 of the upper tank 18b of the first evaporator 18, the right side area of the heat-exchange core portion 18a, the lower tank 18c, the left side area of the heat-exchange core portion 18a, the left side area 28 of the upper tank 18b of the first evaporator 18, and the refrigerant outlet 36, and then flows toward the refrigerant suction side of the compressor 11. A communication hole, through which the refrigerant from the diffuser portion 17d of the ejector 17 flows into the right side area 31 of the upper tank 21b of the second evaporator 21, is provided in the partition plate 33 that is located in the tank inner space of the upper tank 21b of the second evaporator 21.

The refrigerant of the refrigerant branch passage 19 inside the connection block 34 passes through the throttle mechanism (e.g., capillary tube) 20 brazed to a top surface of the upper tanks 18b, 21b, the right side area 31 of the upper tank 21b of the second evaporator 21, the right side area of the heat-exchange core portion 21a, the lower tank 21c, the left side area of the heat-exchange core portion 21a, and the left side area 30 of the upper tank 21b of the second evaporator 21, and then is drawn into the refrigerant suction port 17b of the ejector 17.

As shown in FIG. 1, the other refrigerant branched at the first branch portion 100 flows into the second refrigerant passage 14, and is decompressed by a second expansion valve 37 located in the second refrigerant passage 14. Similarly to the first expansion valve 15, the second expansion valve 37 is a thermal expansion valve that is generally known. The second expansion valve 37 is provided with a temperature sensing portion 37a located in the second refrigerant passage 14 at a downstream side of the third evaporator 38 in a refrigerant flow. The second expansion valve 37 is configured to adjust its valve open degree such that a super-heating degree of the refrigerant at the refrigerant outlet of the third evaporator 38 approaches a predetermined value that is set based on a refrigerant temperature and a refrigerant pressure at the refrigerant outlet of the third evaporator 38. As the second expansion valve 37, a thermal expansion valve constructed of a mechanical mechanism, or an electrical expansion valve may be used. When the electrical expansion valve is used as the second expansion valve 37, the valve open degree of the second expansion valve 37 is electrically controlled based on detection signals of a refrigerant temperature sensor and a refrigerant pressure sensor.

A third evaporator 38 is located in the second refrigerant passage 14 downstream of the second expansion valve 37 in a refrigerant flow. The third evaporator 38 is located to cool air (i.e., air to be cooled) blown by an electrical blower 39 into a space 40 to be cooled. For example, the space 40 to be cooled is a rear seat area (rear space) in the passenger compartment. In this case, the evaporator unit 23 is located to perform an air conditioning of the front space in the passenger compartment, and the third evaporator 38 is located to perform an air conditioning of the rear space in the passenger compartment.

The operation of the refrigeration cycle device 10 according to the first embodiment will be now described. FIG. 3 is a Mollier diagram showing refrigerant states of the refrigerant cycle in an ideal operation of the refrigeration cycle device 10.

When the compressor 11 is driven and operated by the vehicle engine, the compressor 11 draws and compresses refrigerant, and discharges the compressed refrigerant as in the point “a” in FIG. 3. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the radiator 12, and is radiated and cooled by performing a heat exchange with air blown by a cooling fan. The high-pressure refrigerant flowing out of the radiator 12 flows into the liquid receiver 12a, in which the refrigerant is separated into gas and liquid phases (“a” point→“b” point of FIG. 3). The liquid refrigerant separated at the receiver 12a flows into the first branch portion 100, and is branched at the first branch portion 100 to flow into the first refrigerant passage 13 and the second refrigerant passage 14.

The refrigerant flowing into the first refrigerant passage 13 from the first branch portion 100 is decompressed by the first expansion valve 15 (“b” point→“c” point of FIG. 3).

The refrigerant decompressed by the first expansion valve 15 is further decompressed by the pressure-loss generation mechanism 16 (“c” point→“d” point of FIG. 3). Because the pressure-loss generation mechanism 16 is constructed of a throttle mechanism to further decompress the refrigerant, the refrigerant evaporation pressure (refrigerant evaporation temperature) of the first and second evaporators 18, 21 can be reduced. Furthermore, because the refrigerant pressure is reduced in the pressure-loss generation mechanism 16 to cause a pressure loss, the flow amount of refrigerant flowing into the first refrigerant passage 13 can be relatively reduced, and the flow amount of refrigerant flowing into the second refrigerant passage 14 can be relatively increased.

The refrigerant having passed through the first expansion valve 15 and the pressure-loss generation mechanism 16 has an intermediate pressure, and flows into the nozzle portion 17a of the ejector 17 to be decompressed and expanded (“d” point→“e” point of FIG. 3). Thus, the pressure energy of the refrigerant is converted to the velocity energy thereof at the nozzle portion 17a. The refrigerant from a refrigerant jet port of the nozzle portion 17a is ejected at high velocity. The decrease in refrigerant pressure around the refrigerant jet port of the nozzle portion 17a causes the refrigerant (gas-phase refrigerant) having passed through the second evaporator 21 of the refrigerant branch passage 19 to be drawn into the ejector 17 from the refrigerant suction port 17b.

The refrigerant ejected from the nozzle portion 17a and the refrigerant drawn into the refrigerant suction port 17b are mixed in the mixing portion 17c (“e” point “f” point of FIG. 3) located on the downstream side of the nozzle portion 17a, and then flow into the diffuser portion 17d. The velocity (expansion) energy of the refrigerant is converted to the pressure energy thereof by enlarging the passage area in the diffuser portion 17d, resulting in an increased pressure of the refrigerant (“f” point→“g” point of FIG. 3).

The refrigerant flowing from the diffuser portion 17d of the ejector 17 flows into the first evaporator 18, and is evaporated by absorbing heat from air blown by the electrical blower 24 as indicated from “g” point to “h” point of FIG. 3. During this time, in the heat-exchange core portion 18a of the first evaporator 18, the low-temperature and low-pressure refrigerant absorbs heat from the blown air indicated by the arrow “X” to be evaporated. The gas-phase refrigerant after evaporation in the first evaporator 18 is drawn into the compressor 11 via the join portion 110, and compressed again by the compressor 11 as indicated from “h” point to “a” point of FIG. 3.

On the other hand, the refrigerant branched by the second branch portion 120 from the first refrigerant passage 13 into the refrigerant branch passage 19 is decompressed by the throttle mechanism 20 as indicated from “d” point to “i” point of FIG. 3. The refrigerant decompressed by the throttle mechanism 20 flows into the second evaporator 21, and is evaporated in the second evaporator 21 by absorbing heat from air blown by the electrical blower 24, thereby to gradually decrease the refrigerant pressure as indicated from “i” point to “j” point of FIG. 3. The refrigerant flowing out of the second evaporator 21 is drawn into the ejector 17 from the refrigerant suction port 17b, as indicated from “j” point to “f” point of FIG. 3.

On the other hand, the refrigerant flowing from the first branch portion 100 into the second refrigerant passage 14 is decompressed by the second expansion valve 37 as indicated from “b” point to “k” point of FIG. 3.

The refrigerant decompressed by the second expansion valve 37 flows into the third evaporator 38, and is evaporated in the third evaporator 38 by absorbing heat from air blown by the electrical blower 39, as indicated from “k” point to “h” point of FIG. 3. Here, the refrigerant outlet side of the first evaporator 18 and the refrigerant outlet side of the third evaporator 38 are connected at the refrigerant suction side of the compressor 11 via the join portion 110. Therefore, the refrigerant evaporation pressure (refrigerant evaporation temperature) of the first evaporator 18 is same as the refrigerant evaporation pressure (refrigerant evaporation temperature) of the third evaporator 38. Therefore, the refrigerant evaporated at the third evaporator 38 is drawn into the compressor 11 via the join portion 110 to be compressed again in the compressor 11, as indicated from “h” point to “a” point of FIG. 3.

The refrigeration cycle device 10 according to the first embodiment has the following advantages and effects.

Because the pressure-loss generation mechanism 16 is provided at a refrigerant outlet side of the first expansion valve 15 in the first refrigerant passage 13, the refrigerant branched at the first branch portion 100 is easy to flow into the second refrigerant passage 14, so that the flow amount of refrigerant flowing into the second refrigerant passage 14 can be increased relatively as compared with the flow amount of refrigerant flowing into the first refrigerant passage 13. Therefore, the cooling capacity (cooling performance) of the third evaporator 38 can be increased, thereby preventing the cooling of the rear space of the passenger compartment from being delayed.

Because the refrigerant evaporation pressure (refrigerant evaporation temperature) in the first and second evaporators 18, 21 is decreased by the pressure-loss generation mechanism 16, it is also possible to decrease the refrigerant evaporation pressure (refrigerant evaporation temperature) of the third evaporator 38.

As a result, as shown in FIG. 4, when the pressure-loss generation mechanism 16 is provided in the first refrigerant passage 13, the cooling capacity (cooling performance) of the third evaporator 38 can be increased as compared with a case without the pressure-loss generation mechanism 16, and thereby a difference between the cooling capacity of the evaporator unit 23 and the cooling capacity of the third evaporator 38 can be reduced.

Second Embodiment

A refrigeration cycle device 10 according to a second embodiment will be described with reference to FIGS. 5 and 6. In the second embodiment, the parts of the refrigeration cycle device 10 different from those of the first embodiment will be mainly described.

In the above-described first embodiment, the pressure-loss generation mechanism 16 is located at a refrigerant outlet side of the first expansion valve 15 at a position between the thermal expansion valve 15 and the second branch portion 120. However, in the second embodiment, the pressure-loss generation mechanism 16 is located in the first refrigerant passage 13 between a refrigerant outlet side of the ejector 17 and the join portion 110. In the example of FIG. 5, the pressure-loss generation mechanism 16 is located in the first refrigerant passage 13 at a position between the refrigerant outlet side of the first evaporator 18 and the join portion 110.

Next, operation of the refrigeration cycle device 10 according to the second embodiment will be described with reference to FIG. 6. FIG. 6 is a Mollier diagram showing refrigerant states of a refrigerant cycle in an ideal operation of the refrigeration cycle device 10.

According to the second embodiment of the present invention, when the compressor 11 is driven by an engine for running a vehicle, the refrigerant discharged from the compressor 11 is radiated and cooled as indicated from “a” point to “b” point of FIG. 6, and is branched at the first branch portion 100 to flow into the first refrigerant passage 13 and the second refrigerant passage 14.

The refrigerant flowing from the first branch portion 100 into the first refrigerant passage 13 is decompressed by the first expansion valve 15, as indicated from “b” point to “c” point of FIG. 6, similarly to the first embodiment. Then, a part of the refrigerant flowing from the first expansion valve 15 is further decompressed by a nozzle portion 17a of the ejector 17, and is mixed with the refrigerant flowing out of the second evaporator 21 in the mixing portion 17c. The mixed refrigerant in the mixing portion 17c of the ejector 17 is pressurized in the diffuser portion 17d of the ejector 17, and is evaporated in the first evaporator 18 (“c” point→“e” point→“f” point→“g” point→“g′” point of FIG. 6).

The gas refrigerant evaporated in the first evaporator 18 is further decompressed by the pressure-loss generation mechanism 16, and is drawn into the compressor 11 to be compressed again (“g′” point→“h” point→“a” point of FIG. 6). A decrease part of the refrigerant pressure, due to the pressure-loss generation mechanism 16, is set to be smaller than an increase part of the refrigerant pressure pressurized in the diffuser portion 17d of the ejector 17.

The refrigerant is branched at the second branch portion 120 to flow into the refrigerant branch passage 19 from the first refrigerant passage 13. The refrigerant flowing into the refrigerant branch passage 19 is decompressed by the throttle mechanism 20, and flows into the second evaporator 21 to be evaporated. The evaporated refrigerant flowing out of the second evaporator 21 is drawn into the ejector 17 from the refrigerant suction port 17b of the ejector 17 (“c” point→“i” point→“j” point→“f” point of FIG. 6).

On the other hand, the refrigerant flowing into the second refrigerant passage 14 from the first branch portion 100 is decompressed by the second expansion valve 37, flows into the third evaporator 38 to be evaporated, and is drawn into the compressor 11 via the join portion 110 to be compressed (“b” point→“k” point→“h” point→“a” point of FIG. 6).

The refrigerant outlet side of the pressure-loss generation mechanism 16 and the refrigerant outlet side of the third evaporator 38 are connected to the refrigerant suction side of the compressor 11 via the join portion 110. Therefore, the refrigerant evaporation pressure (refrigerant evaporation temperature) of the third evaporator 38 can be made lower than that of the first evaporator 18. That is, a pressure part decompressed from “g′” point to “h” point corresponds to a pressure difference between the refrigerant evaporation pressure of the first evaporator 18 and the refrigerant evaporation pressure of the third evaporator 38.

According to the refrigeration cycle device 10 of the second embodiment, the other parts are similar to those of the above-described first embodiment. Therefore, the effects described in the first embodiment can be obtained. Furthermore, in the second embodiment, because the refrigerant flowing out of the first evaporator 18 is further decompressed, the refrigerant evaporation pressure and the refrigerant evaporation temperature of the third evaporator 38 can be reduced than that of the first evaporator 18.

Third Embodiment

A third embodiment of the present invention will be described. In the third embodiment, the parts different from those of the refrigeration cycle device 10 of the above-described first and second embodiments are mainly described. The first embodiment of the present invention is modification examples of the above-described first and second embodiments.

In the above-described first and second embodiments, a throttle mechanism is used as the pressure-loss generation mechanism 16. However, in the third embodiment, the first branch portion 100 or the join portion 110 is configured so that the pressure of the refrigerant flowing into the first refrigerant passage 13 is reduced. That is, in the third embodiment, the first branch portion 100 or the join portion 110 is used for not only a join portion of the first refrigerant passage 13 and the second refrigerant passage 14, but also a pressure-loss generation mechanism. Therefore, it is unnecessary to form the pressure-loss generation mechanism 16 described in the first or second embodiment.

First, an example, in which the first branch portion 100 also functions as the pressure-loss generation mechanism, will be described. The first branch portion 100 may be a three-way joint. In the above-described first or second embodiment, an inflow direction of the refrigerant flowing from the branch portion 100 into the first refrigerant passage 13 is about 90° relative to an inflow direction of refrigerant flowing into the first branch portion 100 from the radiator 12, while an inflow direction of the refrigerant flowing from the branch portion 100 into the second refrigerant passage 14 is about 1800 relative to the inflow direction of refrigerant flowing into the first branch portion 100 from the radiator 12. The three-way joint configuration of the first branch portion 100 described in the first and second embodiments is one example of the third embodiment. In the third embodiment, the first branch portion 100 is configured such that an angle between the inflow direction of the refrigerant flowing from the branch portion 100 into the first refrigerant passage 13 and the inflow direction of refrigerant flowing into the first branch portion 100 from the radiator 12 is smaller than an angle between the inflow direction of the refrigerant flowing from the branch portion 100 into the second refrigerant passage 14 and the inflow direction of refrigerant flowing into the first branch portion 100 from the radiator 12.

Accordingly, in the third embodiment, a flow direction of refrigerant flowing from the first branch portion 100 into the first refrigerant passage 13 can be bent more than a flow direction of refrigerant flowing from the first branch portion 100 into the second refrigerant passage 14 relative to the inflow direction of refrigerant flowing into the first branch portion 100, thereby reducing the pressure of refrigerant flowing into the first refrigerant passage 13 at the first branch portion 100. Thus, the refrigerant branched at the first branch portion 100 is easy to flow into the second refrigerant passage 14, thereby increasing a refrigerant flow amount of the second refrigerant passage 14 as compared with a refrigerant flow amount of the first refrigerant passage 13. That is, the first branch portion 100 is also used as a pressure-loss generation mechanism for generating a pressure loss.

Next, an example in which the join portion 110 functions as the pressure-loss generation mechanism will be described. The join portion 110 may be a three-way joint. In the above-described first or second embodiment, an inflow direction of the refrigerant flowing into the join portion 110 from the first refrigerant passage 13 is about 900 relative to a flowing-out direction of refrigerant flowing out of the join portion 110 toward the refrigerant suction side of the compressor 11, while an inflow direction of the refrigerant flowing into the join portion 110 from the second refrigerant passage 14 is about 180° relative to the flowing-out direction of refrigerant flowing out of the join portion 110 toward the refrigerant suction side of the compressor 11. The three-way joint configuration of the join portion 110 described in the first and second embodiments is one example of the third embodiment. In the third embodiment, the join portion 110 is configured such that an angle between the inflow direction of the refrigerant flowing into the join portion 110 from the first refrigerant passage 13 and the flowing-out direction of refrigerant flowing out of the join portion 110 toward the refrigerant suction side of the compressor 11 is smaller than the inflow direction of the refrigerant flowing into the join portion 110 from the second refrigerant passage 14 and the flowing-out direction of refrigerant flowing out of the join portion 110 toward the refrigerant suction side of the compressor 11.

Accordingly, in the third embodiment, a flow direction of refrigerant flowing from the first refrigerant passage 13 into the join portion 110 can be bent more than a flow direction of refrigerant flowing from the second refrigerant passage 14 into the join portion 110, thereby reducing the pressure of refrigerant flowing in the first refrigerant passage 13 at the join portion 110. Thus, the refrigerant branched at the first branch portion 100 is easy to flow into the second refrigerant passage 14, thereby increasing a refrigerant flow amount of the second refrigerant passage 14 as compared with a refrigerant flow amount of the first refrigerant passage 13.

In the third embodiment, one of the first branch portion 100 and the join portion 110 may function as the pressure-loss generation mechanism, or both the first branch portion 100 and the join portion 110 may function as the pressure-loss generation mechanism.

Fourth Embodiment

A fourth embodiment of the present invention will be described. In the fourth embodiment, the parts different from those of the refrigeration cycle device 10 of the above-described first and second embodiments are mainly described. The fourth embodiment is another modification examples of the above-described first and second embodiments.

In the above-described first and second embodiments, a throttle mechanism is used as the pressure-loss generation mechanism 16. However, in the fourth embodiment, the pressure-loss generation mechanism 16 is omitted. In the fourth embodiment, a passage cross-section area of the first refrigerant passage 13 is made smaller than a passage cross-section area of the second refrigerant passage 14, so that the pressure of refrigerant flowing into the first refrigerant passage 13 can be reduced.

Because the pressure of the refrigerant flowing into the first refrigerant passage 13 is reduced, it is possible to reduce the flow amount of the refrigerant flowing into the first refrigerant passage 13. Thus, the refrigerant branched at the first branch portion 100 easily flows into the second refrigerant passage 14, thereby increasing the flow amount of refrigerant flowing into the second refrigerant passage 14 with respect to the first refrigerant passage 13.

The passage cross-section area of the first refrigerant passage 13 may be made smaller than that of the second refrigerant passage 14 in the entire length of the first refrigerant passage 13, or in a part of the first refrigerant passage 13. The cross-sectional area of the first refrigerant passage 13 can be partially made smaller than that of the second refrigerant passage 14 at a position corresponding to the pressure-loss generation mechanism 16 of the first or second embodiment. In the fourth embodiment, the other parts may be similar to those of the above-described first or second embodiment, and thereby the advantages and effects described in the first or second embodiment can be obtained.

Other Embodiments

The invention is not limited to the disclosed embodiments, and various modifications can be made to the embodiments as follows.

(1) For example, in the present embodiments, refrigerant whose high-pressure side pressure does not exceed the critical pressure, such as a flon-based or HC-based refrigerant, is used as the refrigerant for the refrigeration cycle device 10 to form a vapor-compression subcritical cycle. However, the present invention may be applied to a refrigeration cycle device with a vapor-compression supercritical cycle in which the refrigerant pressure on a high-pressure side becomes higher than the critical pressure of the refrigerant. For example, carbon dioxide may be used as the refrigerant in a super-critical refrigerant cycle.

In the super-critical refrigeration cycle device, the refrigerant discharged from the compressor 11 is cooled and radiated without being condensed. In this case, it is unnecessary to provide the liquid receiver 12a, and the liquid receiver 12a may be omitted. In the super-critical refrigeration cycle device, an accumulator used as a low-pressure side gas-liquid separator may be located at a refrigerant outlet side of the first evaporator 18 while the liquid receiver 12a is omitted.

(2) In the above-described embodiments, the first and second evaporators 18, 21 are located to cool the front seat area in the passenger compartment, and the third evaporator 38 is located to cool the rear seat area in the passenger compartment. However, the space to be cooled by the first and second evaporators 18, 21 and the space to be cooled by the third evaporator 38 may be suitably changed without being limited to the above-described embodiments. For example, the refrigeration cycle device 10 may be used for a fixed room to cool different spaces.

(3) In the above-described first embodiment, the pressure-loss generation mechanism 16 is located in the first refrigerant passage 13 at a position between the refrigerant outlet side of the expansion valve 15 and the second branch portion 120. However, the pressure-loss generation mechanism 16 may be located in the first refrigerant passage 13 at a position between the first branch portion 100 and the refrigerant inlet side of the expansion valve 15. Even in this case, it is possible to reduce the pressure of the refrigerant flowing in the first refrigerant passage 13, and to increase the flow amount of refrigerant flowing into the second refrigerant passage 14, thereby increasing the flow amount of refrigerant flowing into the third evaporator 38 in the second refrigerant passage 14.

(4) In the above-described second embodiment, the pressure-loss generation mechanism 16 is located in the first refrigerant passage 13 at a position between the refrigerant outlet side of the first evaporator 18 to the join portion 110. However, a pressure-loss generation mechanism may be located in a refrigerant passage from the diffuser portion 17d of the ejector 17 to the first evaporator 18, or may be located inside the integrated unit 22. Even in this case, it is possible to reduce the pressure of the refrigerant flowing in the first refrigerant passage 13, and to increase the flow amount of refrigerant flowing into the second refrigerant passage 14, thereby increasing the flow amount of refrigerant flowing into the third evaporator 38.

(5) In the above-described embodiments, both the first and second evaporators 18, 21, the ejector 17 and the throttle mechanism 20, etc., are integrated to form the integrated unit 22. However, the ejector 17 and the throttle mechanism 20 may be separately provided from the first and second evaporators 18, 21 that are located to cool a common space. That is, in the above-described embodiments, at least one of the components of the integrated unit 22 including the second branch portion 120, the ejector 17, the throttle mechanism 20 and the first and second evaporators 18, 21 may be separately formed in the refrigeration cycle device 10. Alternatively, all the components of the integrated unit 22 including the second branch portion 120, the ejector 17, the throttle mechanism 20 and the first and second evaporators 18, 21 may be separately formed from each other in the refrigeration cycle device 10.

(6) In the above-described embodiments, the components of the first and second evaporators 18, 21 are made of aluminum, and are brazed integrally. However, the first and second evaporators 18, 21 may be integrated by using a fastening member such as a bolt while having a predetermined distance therebetween. Furthermore, the fins 27 of the first evaporator 18 and the second evaporator 21 may be formed in common, while the tubes 26 of the first evaporator 18 are formed separately from the tubes 26 of the second evaporator 21.

(7) In the above-described embodiments, the first evaporator 18 having a relatively high refrigerant temperature may be located at a downstream air side of the second evaporator 21 having a relatively low refrigerant temperature in the air flow direction X. Alternatively, the first evaporator 18 and the second evaporator 21 may be separated from each other to cool different spaces.

(8) In the above-described embodiments, the throttle mechanism 20 provided in the refrigerant branch passage 19 is constructed of a capillary tube. However, the throttle mechanism 20 provided in the refrigerant branch passage 19 may be constructed of any fixed throttle such as an orifice.

(9) The pressure-loss generation mechanisms 16 described in the above embodiments may be suitably combined.

(10) In the above-described embodiments, the refrigeration cycle device 10 is operated to set a dual operation mode in which the front seat area in the passenger compartment is cooled by using the first and second evaporators 18, 21, and the rear seat area in the passenger compartment is cooled by using the third evaporator 38. However, the refrigeration cycle device 10 may be configured to be capable of switching between the dual operation mode and a single operation mode. In the single operation mode, only the front seat area in the passenger compartment is cooled by using the first and second evaporators 18, 21.

For example, in the refrigeration cycle device 10, a mode switching device is located to switch an operation mode between the dual operation mode and the single operation mode, and the pressure-loss generation mechanism 16 is constructed of a variable throttle. When the single operation mode is set, the operation of the electrical blower 39 is stopped, and the pressure-loss generation mechanism 16 constructed of the variable throttle is fully opened. Thus, the flow amount of refrigerant flowing into the first refrigerant passage 13 can be increased so as to increase the cooling capacity of the first and second evaporators 18, 21. Furthermore, a pressure increasing amount in the diffuser 17d of the ejector 17 can be increased, thereby increasing the pressure of the refrigerant to be drawn into the compressor 11. Thus, in the single operation mode, the cycle efficiency (COP) of the refrigeration cycle device can be improved while the cooling capacity of the first and second evaporators 18, 21 can be increased.

In the single operation mode, because the electrical blower 39 is not operated, heat exchange is substantially not performed in the third evaporator 38. Furthermore, an opening/closing valve for opening or closing the second refrigerant passage 14 may be provided. In this case, the opening/closing valve may be configured to close the second refrigerant passage 14 when the single operation mode is set, and to open the second refrigerant passage when the dual operation mode is set.

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

Refrigeration cycle device

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Priority Claims (1)