Patent Application
20090283247
This application is based on Japanese Patent Applications No. 2008-130890 filed on May 19, 2008, the contents of which are incorporated herein by reference in its entirety.
The present invention relates to an evaporator unit that includes an evaporator and a capillary tube. The evaporator unit can be suitably used for a refrigerant cycle device, for example.
An evaporator unit including an evaporator and a capillary tube is described in JP 2007-192504A or JP 2005-308384A, for example. Furthermore, an evaporator unit for a refrigerant cycle,device having an ejector is described in JP 2007-192504A, JP 2005-308384A, JP 2007-57222A or JP 6-137695A, for example.
In the evaporator unit described in JP 2007-192504A or JP 2005-308384A, the capillary tube is brazed to the evaporator to be bonded and sealed at its two ends. However, according to detail studies regarding bonding portion of the capillary tube by the inventors of the present application, the capillary tube may vibrate in accordance with the refrigerant flowing in the capillary tube, and a crack may be caused in the bonding portions at the two ends of the capillary tube, thereby causing a refrigerant leakage.
In view of the foregoing problems, it is an object of the present invention to provide an evaporator unit including a capillary tube and an evaporator, which can prevent a crack from being caused in bonding portions at two longitudinal ends of the capillary tube.
According to an aspect of the present invention, an evaporator unit includes an evaporator configured to evaporate a refrigerant, and a capillary tube configured to decompress the refrigerant. The capillary tube has two ends in a longitudinal direction of the capillary tube, and a middle portion between the two ends in the longitudinal direction. Furthermore, the two ends of the capillary tube are bonded to the evaporator, and at least one position of the middle portion of the capillary tube is fixed to the evaporator by press-contacting the evaporator. Thus, vibration of the capillary tube due to the refrigerant flow can be effectively reduced. Accordingly, the vibration of the capillary tube at the two longitudinal ends (i.e., at inlet and outlet) can be reduced, thereby preventing a crack of the bonding portions at the two longitudinal ends of the capillary tube.
Here, the two ends of the capillary tube can be directly bonded to the evaporator or can be indirectly bonded to the evaporator. The middle portion of the capillary tube may be press-fitted to the evaporator at plural positions in a zigzag shape.
The evaporator may have a plurality of tubes in which the refrigerant flows, and a tank extending in a tank longitudinal direction that is in parallel with an arrangement direction of the tubes to distribute the refrigerant into the tubes or to collect the refrigerant from the tubes. Furthermore, the tank may include a plate header having tube-insertion holes into which one-side ends of the tubes are inserted, and a tank header bonded to the plate header to form a tank space between the plate header and the tank header. In this case, the middle portion of the capillary tube is press-fitted to the tank header of the evaporator at least one position.
For example, the tank header may have at least one protrusion portion protruding to a position of the middle portion of the capillary tube, and the middle portion of the capillary tube may be press-fitted to the protrusion portion of the tank header. Furthermore, the tank header may have a valley portion extending along a longitudinal direction of the tank header and being recessed such that the capillary tube is inserted in the valley portion in a radial direction of the capillary tube. In this case, the protrusion portion protrudes from the valley portion to the middle portion of the capillary tube to press-contact the middle portion of the capillary tube.
The protrusion portion may protrude from the tank header by a dimension, to press-contact an outer surface of the capillary tube, and to bend the capillary tube. Alternatively, a plurality of the protrusion portions may be arranged by a predetermined distance in the longitudinal direction of the capillary tube. For example, the predetermined distance is equal to or smaller than 75 mm.
According to another aspect of the present invention, an evaporator unit includes an evaporator configured to evaporate a refrigerant, and a capillary tube configured to decompress the refrigerant. The evaporator includes a plurality of tubes in which the refrigerant flows, and a tank extending in a tank longitudinal direction that is in parallel with an arrangement direction of the tubes to distribute the refrigerant into the tubes or to collect the refrigerant from the tubes. Furthermore, the tank has a valley portion extending along the tank longitudinal direction and being recessed, and at least one protrusion portion protruding from the valley portion. In addition, the capillary tube is inserted in the valley portion in a radial direction of the capillary tube to extend in the tank longitudinal direction, two longitudinal ends of the capillary tube are bonded to the evaporator to be fixed thereto, and the capillary tube is press-fitted to the protrusion portion at a middle portion between the two longitudinal ends of the capillary tube. Accordingly, the vibration of the capillary tube at the two longitudinal ends (i.e., inlet and outlet) can be reduced, thereby preventing a crack of the bonding portions at the two longitudinal ends of the capillary tube.
For example, the tank may have a plurality of protrusion portions protruding from the valley portion to positions of the middle portion of the capillary tube on both sides of the valley portion. In this case, the protrusion portions are offset from each other in the tank longitudinal direction, and the middle portion of the capillary tube is partially press-fitted to the protrusion portions of the tank. Accordingly, vibrations due to the refrigerant flow can be effectively reduced.
Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of embodiments when taken together with the accompanying drawings. In the drawings:
A first embodiment of the present invention and modifications of the first embodiment will be described below with reference to
The evaporator unit is connected to other components of the refrigerant cycle device, including a condenser (refrigerant cooler), a compressor, and the like, via piping. The evaporator unit of the present embodiment is used for application to an indoor equipment (i.e., evaporator) for cooling air. However, the evaporator unit may be used as an outdoor equipment in other examples.
In an ejector refrigerant cycle device 10 shown in
As the compressor 11, may be used either a variable displacement compressor which can adjust a refrigerant discharge capability by a change in discharge capacity, or a fixed displacement compressor which can adjust a refrigerant discharge capability by changing an operating ratio of the compressor through engagement and disengagement of an electromagnetic clutch 11a. If an electric compressor is used as the compressor 11, the refrigerant discharge capability of the compressor 11 can be adjusted or regulated by adjustment of the number of revolutions of an electric motor.
A refrigerant radiator 12 is disposed on a refrigerant discharge side of the compressor 11. The radiator 12 exchanges heat between the high-pressure refrigerant discharged from the compressor 11 and outside air (i.e., air outside a compartment of a vehicle) blown by a cooling fan (not shown) thereby to cool the high-pressure refrigerant.
As the refrigerant for the ejector refrigerant cycle device 10 in the present embodiment, is used a refrigerant whose high pressure does not exceed a critical pressure, such as a flon-based refrigerant, or a HC-based refrigerant, so as to form a vapor-compression subcritical cycle. Thus, the radiator 12 serves as a condenser for cooling and condensing the refrigerant in this embodiment.
A liquid receiver 12a is provided at a refrigerant outlet side of the radiator 12. The liquid receiver 12a has an elongated tank-like shape, as is known generally, and constitutes a vapor-liquid separator for separating the refrigerant into vapor and liquid phases to store therein an excessive liquid refrigerant of the refrigerant cycle. At a refrigerant outlet of the liquid receiver 12a, the liquid refrigerant is derived from the lower part of the interior in the tank-like shape. In the present embodiment, the liquid receiver 12a is integrally formed with the radiator 12.
The radiator 12 may have a known structure which includes a first heat exchanger for condensation positioned on the upstream side of a refrigerant flow, the liquid receiver 12a for allowing the refrigerant introduced from the first heat exchanger for condensation and for separating the refrigerant into vapor and liquid phases, and a second heat exchanger for supercooling the saturated liquid refrigerant from the liquid receiver 12a.
A thermal expansion valve 13 is disposed on an outlet side of the liquid receiver 12a. The thermal expansion valve 13 is a decompression unit for decompressing the liquid refrigerant flowing from the liquid receiver 12a, and includes a temperature sensing part 13a disposed in a refrigerant suction passage of the compressor 11.
The thermal expansion valve 13 detects a degree of superheat of the refrigerant at the compressor suction side based on the temperature and pressure of the suction side refrigerant of the compressor 11, and adjusts an opening degree of the valve, such that the superheat degree of the refrigerant on the compressor suction side becomes a predetermined value which is preset, as is known generally. Therefore, the thermal expansion valve 13 adjusts a refrigerant flow amount such that the superheat degree of the refrigerant on the compressor suction side becomes the predetermined value.
An ejector 14 is disposed at a refrigerant outlet side of the thermal expansion valve 13. The ejector 14 is decompression means for decompressing the refrigerant as well as refrigerant circulating means (kinetic vacuum pump) for circulating the refrigerant by a suction effect (entrainment effect) of the refrigerant flow jetted at high speed.
The ejector 14 includes a nozzle portion 14a for further decompressing and expanding the refrigerant (i.e., the middle-pressure refrigerant from the expansion valve) by restricting a path area of the refrigerant having passed through the expansion valve 13 to a small level. A refrigerant suction port 14b is provided in the ejector 14 in the same space as a refrigerant jet port of the nozzle portion 14a so as to draw the vapor-phase refrigerant from a second evaporator 18 as described later.
A mixing portion 14c is provided on a downstream side of the refrigerant flow of the nozzle portion 14a and the refrigerant suction port 14b, for mixing a high-speed refrigerant flow jetted from the nozzle portion 14a and the refrigerant drawn from the refrigerant suction port 14b.
A diffuser 14d serving as a pressure-increasing portion is provided on a downstream side of the refrigerant flow of the mixing portion 14c in the ejector 14. The diffuser 14d is formed in such a manner that a path area of the refrigerant is generally increased toward downstream from the mixing portion 14c. The diffuser 14d serves to increase the refrigerant pressure by decelerating the refrigerant flow, that is, to convert the speed energy of the refrigerant into the pressure energy.
A first evaporator 15 is connected to an outlet side of the diffuser 14d of the ejector 14. A refrigerant outlet side of the first evaporator 15 is coupled to a refrigerant suction side of the compressor 11.
On the other hand, a refrigerant branch passage 16 is provided to be branched from a branch portion at an inlet side of the nozzle portion 14a of the ejector 14. That is, the refrigerant branch passage 16 is branched at the branch portion between the refrigerant outlet of the thermal expansion valve 13 and the refrigerant inlet of the nozzle portion 14a of the ejector 14. The downstream end side of the refrigerant branch passage 16 is connected to the refrigerant suction port 14b of the ejector 14. A point Z of
In the refrigerant branch passage 16, a throttle 17 (e.g., capillary tube 17a) is disposed to decompress the refrigerant passing therethrough. On the refrigerant flow downstream side of the throttle 17 in the refrigerant branch passage 16, the second evaporator 18 is disposed. The throttle 17 serves as a decompression unit which decompresses the refrigerant while performing a function of adjusting a refrigerant flow amount flowing into the second evaporator 18. More specifically, the throttle 17 can be constructed with a fixed throttle, such as a capillary tube, or an orifice.
In the first embodiment, the two evaporators 15 and 18 are incorporated into an integrated structure with an arrangement as described later. The two evaporators 15 and 18 are accommodated in an air conditioning case not shown, and the air (air to be cooled) is blown by a common electric blower 19 through an air passage formed in the air conditioning case in the direction of an arrow “A”, so that the blown air is cooled by the two evaporators 15 and 18.
The cooled air by the two evaporators 15 and 18 is fed to a common space to be cooled (not shown). This causes the two evaporators 15 and 18 to cool the common space to be cooled. Among these two evaporators 15 and 18, the first evaporator 15 connected to a main flow path on the downstream side of the ejector 14 is disposed on the upstream side (upwind side) of the air flow A, while the second evaporator 18 connected to the refrigerant suction port 14b of the ejector 14 is disposed on the downstream side (downwind side) of the air flow A.
When the ejector refrigerant cycle device 10 of the present embodiment is used as a refrigeration cycle for a vehicle air conditioner, the space within a passenger compartment of the vehicle is the space to be cooled. When the ejector refrigerant cycle device 10 of the present embodiment is used for a refrigeration cycle for a freezer car, the space within the freezer and refrigerator of the freezer car is the space to be cooled.
In the present embodiment, the ejector 14, the first and second evaporators 15 and 18, and the throttle 17 are incorporated into one integrated unit so as to form an evaporator unit 20.
Now, specific examples of the evaporator unit 20 will be described below in detail with reference to
First, an example of the integrated unit (evaporator unit 20) including the two evaporators 15 and 18 will be explained below with reference to
In the example of the evaporator unit 20 of
The first evaporator 15 and the second evaporator 18 have the same basic structure, and include heat exchange cores 15a and 18a, and tanks 15b, 15c, 18b, and 18c positioned on both upper and lower sides of the heat exchange cores 15a and 18a, respectively.
The heat exchanger cores 15a and 18a respectively include a plurality of tubes 21 extending in a tube longitudinal direction (e.g., top-bottom direction in
In
The tube 21 constitutes the refrigerant passage through which refrigerant flows, and is made of a flat tube having a flat cross-sectional shape in the air flow direction A. The fin 22 is a corrugated fin made by bending a thin plate in a wave-like shape, and is connected to a flat outer surface of the tube 21 to increase a heat transfer area of the air side.
The tanks 15b and 15c are located, respectively, at top and bottom sides of the heat exchange core 15a, and the tanks 18b and 18c are located, respectively, at top and bottom sides of the heat exchange core 18a so as to form independent tank spaces independent from the tank spaces of the tanks 15b and 15c. In the first embodiment, the ejector 14 is located in the upper tank 18b, as an example. However, the ejector 14 may be provided at a position different from the upper tank 18b or may be provided outside of the evaporator unit 20.
The tanks 15b, 15c, 18b, 18c are connected to end portions of the tubes 21 in the longitudinal direction to distribute the refrigerant into the tubes 21 and to collect the refrigerant from the tubes 21.
The tanks 15b, 15c located on both the top and bottom sides of the first evaporator 15 have tube-fitting hole part (not shown), and both top and bottom end portions of the tubes 21 of the heat exchange core 15a are inserted into and are bonded to the tube-fitting hole part, such that the both top and bottom end portions of the tubes 21 communicate with the inner space of the tanks 15b, 15c.
Similarly, the tanks 18b, 18c located on both top and bottom sides of the second evaporator 18 have tube-fitting hole part (not shown), and both top and bottom end portions of the tubes 21 of the heat exchange core 18a are inserted into and are bonded to the tube-fitting hole part, such that the both top and bottom end portions of the tubes 21 communicate with the inner space of the tanks 18b, 18c.
The tubes 21 of the heat exchanger core 15a and the tubes 21 of the heat exchanger core 18a independently constitute the respective refrigerant passages. The tanks 15b and 15c on both upper and lower sides of the first evaporator 15, and the tanks 18b and 18c on both upper and lower sides of the second evaporator 18 independently constitute the respective refrigerant passage spaces.
Thus, the tanks 15b, 15c, 18b, and 18c disposed on both upper and lower sides serve to distribute the refrigerant to the respective tubes 21 of the heat exchange cores 15a and 18a, and to collect the refrigerant from the tubes 21 of the heat exchange cores 15a and 18a.
Because the two upper tanks 15b and 18b are arranged adjacent to each other, the two upper tanks 15b and 18b can be molded integrally to form an upper tank portion of the evaporator unit 20. The same can be made for the two lower tanks 15c and 18c so as to form a lower tank portion of the evaporator unit 20. The two upper tanks 15b and 18b may be molded independently as independent components, and that the same can be made for the two lower tanks 15c and 18c.
In the example of
The plate header 30 has an approximately W-like cross section configuring integrally respective bottom-side half portions of the upper tanks 15b, 18b. The top ends of the tubes 21 are inserted into the plate header 30, and are bonded to the plate header 30. The tank header 31 has an approximately M-like cross section configuring integrally respective top-side half portions of the upper tanks 15b, 18b. Each of the plate header 30 and tank header 31 can be formed integrally by molding or pressing.
When the plate header 30 and the tank header 31 are combined in the top-bottom direction, the center portion of the approximately W-like cross section of the plate header 30 and the center portion of the approximately M-like cross 25 section of the tank header 31 are tightly bonded so as to form two cylindrical tank space portions. One side ends (left side ends in
As shown in
A plurality of circular-arc shaped ribs 31b are provided in the tank header 31 at two sides of the valley portion 31a, so as to reinforce the tank header 31. Because the ribs 31b are formed in the tank header 31, the pressure resistance of the tank header 31 can be increased.
The components of the evaporator unit 20, such as the tubes 21, the fins 22, the tanks 15b, 15c, 18b, 18c are made of metal such as aluminum material having a sufficient brazing property, and are brazed integrally so that the entire structure of the first evaporator 15 and the second evaporator 18 are integrally assembled.
For example, the plate header 30 and the tank header 31 are formed from press-molded aluminum plates. The ribs 31b is formed integrally with the tank header 31 while the press-molding.
In the present embodiment, as shown in
The nozzle portion 14a of the ejector 14 has therein a fine passage with a high accuracy. When the ejector 14 is brazed, the nozzle portion 14a may be thermally deformed in the brazing at a high brazing temperature (e.g., 600° C. of aluminum brazing). Thus, if the brazing of the ejector 14 is performed after the ejector 14 is attached to the first and second evaporators 15, 18, the passage shape and the passage dimension of the nozzle portion 14a may be deformed.
Thus, in the present embodiment, the ejector 14 is assumed to the first and second evaporators 15, 18, after the first and second evaporators 15, 18, the joint portion 33 and the capillary tube 17a and the like are integrally brazed.
For example, the ejector 14, the capillary tube 17a and the joint portion 33 may be formed from an aluminum material, similarly to the first and second evaporators 15, 18.
As shown in
Protrusion portions 31c are formed at plural positions of the tank header 31 in the tank longitudinal direction. The protrusion portions 31c protrude from the valley portion 31a to the capillary tube 17a at plural positions of the capillary tube 17a between the two longitudinal ends of the capillary tube 17a. In the present embodiment, the protrusion portions 31c are formed integrally with the tank header 31 by pressing. For example, a part of the wall portion of the tank header 31, defining the tank passage, is pressed to outside, so that the protrusion portions 31c are formed.
The protrusion portions 31c are formed in the tank header 31 at two sides of the valley portion 31a and are offset from each other in the longitudinal direction of the capillary tube 17a. For example, the protrusion portions 31c formed at the two sides of the valley portion 31a may be offset from each other at equal distance in the extending direction (tank longitudinal direction) of the tank header 31.
As an example of the present embodiment, the protrusion portions 31c can be spaced from each other in the longitudinal direction of the tank header 31 by a distance equal to or smaller than 75 mm. Furthermore, a distance from the longitudinal end of the capillary tube 17a to the outmost protrusion portion 31c that is the closest one from the longitudinal end of the capillary tube 17a is also set equal to or smaller than 75 mm.
When viewing the protrusion portions 31c of the tank header 31 from the tank longitudinal direction (i.e., the longitudinal direction of the capillary tube 17a), a clearance between the protrusion portions 31c is slightly smaller than the outer diameter of the capillary tube 17a.
Thus, the capillary tube 17a can be press-fitted between the protrusion portions 31c at the two sides of the valley portion 31a, and is brazed to the protrusion portions 31c in the press-fitted state.
While the evaporator unit 20 is manufactured, a brazing step is performed after a temporarily assemble step. In the temporarily assemble step, the capillary tube 17a is fitted into the valley portion 31a of the tank header 31 from an upper side of the tank header 31. The capillary tube 17a is slightly bent to be pressed to the protrusion portions 31c that are alternately provided at the two sides of the valley portion 31a in the longitudinal direction of the capillary tube 17a.
In the temporarily assemble step, the capillary tube 17a is deformed to be slightly corrugated, and is fitted between the protrusion portions 31c. In the brazing step, the capillary tube 17a is bonded to the protrusion portions 31c of the tank header 31. The capillary tube 17a is bonded to the tank header 31a at its two ends, and is also bonded to the tank header 31a at contact portions contacting the protrusion portions 31c between the two ends of the capillary tube 17a. As shown in
The protrusion portion 31c has a rounded corner portion when being viewed from a direction parallel with tank longitudinal direction (i.e., extending direction of the capillary tube 17a). The rounded corner portion is provided at each of the protrusion portions 31c, so as to prevent the capillary tube 17a from being damaged when the capillary tube 17a is assembled to the header tank 31. Furthermore, because the rounded corner portion is provided at each of the protrusion portions 31c, the capillary tube 17a can be smoothly assembled to the tank header 31.
The joint portion 33 is a member brazed and fixed to a side surface portion positioned at one side (e.g., left side in
As shown in
The joint portion 33 is brazed and fixed to the side surface portion of the upper tanks 15b, 18b. An outlet side opening portion of the branch passage 16a of the joint portion 33 is air-tightly connected to an upstream end portion 17c of the capillary tube 17a by brazing.
The joint portion 33 is brazed to the side surface portion of the upper tanks 15b, 18b, such that the refrigerant outlet 35 communicates with the upper tank 15b, the main passage 34a communicates with the upper tank 18b, and the branch passage 16a communicates with the upstream end portion 17c of the capillary tube 17a.
In the example of
An ejector fixing plate 40 is provided in the upper tank 18b, to fix the diffuser 14d of the ejector 14 and to partition an inner space of the upper tank 18b into a first space 41 and a second space 42. The first space 41 of the upper tank 18b is used as a collection tank space in which the refrigerant having passed through the plural tubes 21 of the second evaporator 18 is collected.
The ejector fixing plate 40 is located approximately at a center portion in the longitudinal direction of the upper tank 18b, and is fixed to the inner wall surface of the upper tank 18b by brazing. A cylindrical portion 40a protruding from the ejector fixing plate 40 in the longitudinal direction of the upper tank 18b is formed from an aluminum material. The cylindrical portion 40a penetrates through a through hole of the elector fixing plate 40. The diffuser 14d is inserted into the cylindrical portion 40a of the ejector fixing plate 40 to be fixed into the cylindrical portion 40a.
As shown in
As shown in
An up-down partition plate 44 is located in the second space 42 of the upper tank 18b approximately at a center portion in an up-down direction of the second space 42, so as to partition the second space 42 of the upper tank 18b into an upper side space 45 and a lower side space 46 within the second space 42, as shown in
The up-down partition plate 44 is formed from an aluminum material, and is fixed to an inner wall surface of the upper tank 18b by brazing. The up-down partition plate 44 is formed into a plate shape extending in the longitudinal direction of the upper tank 18b.
The up-down partition plate 44 is not provided in a space part adjacent to the cap 32 within the second space 42 to form a non-partition space part at the side adjacent to the cap 32, so that refrigerant flows in the second space 42 upwardly through the non-partition space part. Thus, the lower space 46 of the second space 42 communicates with the communication passage of the connection joint 43 through the non-partition space part of the second space 42.
The ejector 14 can be formed from a metal material such as copper or aluminum. Alternatively, the ejector 14 may be formed from a non-metal material such as a resin material. In the present embodiment, after the first and second evaporators 15, 18 and other components are integrally brazed, the ejector 14 is inserted into an inner portion Of the upper tank 18b after penetrating through the ejector-insertion hole portion of the joint portion 33. The ejector-insertion hole portion is closed by the cover member 36 after the ejector 14 is inserted into the inner portion of the upper tank 18b.
The tip end portion (i.e., right end portion of
As shown in
The first space 48 is used as a collection tank space in which the refrigerant after passing through the plural tubes 21 of the first evaporator 15 is joined and collected, and the second space 49 is used as a distribution tank space from which the refrigerant is distributed into the plural tubes 21 of the first evaporator 15.
The upper space 45 of the upper tank 18b of the second evaporator 18 communicates with the second space 49 in the upper tank 15b of the first evaporator 15 via plural communication holes (not shown) between the upper space 45 of the upper tank 18b and the second space 49 of the upper tank 15b.
The ejector 14 is fixed to the upper tanks 15b, 18b of the first and second evaporators 15, 18 in the longitudinal direction of the ejector 14, as follows. First, the ejector 14 is inserted into the upper tank 18b from the ejector-insertion hole portion (not shown) of the joint portion 33, and then the ejector-insertion hole portion is closed by the cover member 36 so that the ejector 14 is fixed to the upper tank 18b by the cover member 36.
In the present embodiment, the inner space of the upper tank 18b of the second evaporator 18 is partitioned into the first and second spaces 41, 42 by the ejector fixing plate 40. The first space 41 is used as a collection tank space in which the refrigerant after passing through the plural tubes 21 is collected, and the second space 42 is used as a distribution tank space from which the refrigerant is distributed into the plural tubes 21.
The ejector 14 has a thin elongated shape extending in the axial direction of the nozzle portion 14a. The longitudinal direction of the ejector 14 is made to correspond to the longitudinal direction of the upper tank 18b, such that the longitudinal direction of the ejector 14 is generally parallel with the longitudinal direction of the upper tank 18b.
Thus, the ejector 14 and the evaporator 18 can be arranged in compact, thereby reducing the size of the evaporator unit 20. Furthermore, the ejector 14 is located in the upper tank 18b such that the refrigerant suction port 14b is directly opened into the first space 41 that is used as the collection tank space.
Thus, it is possible to reduce the number of the refrigerant piping in the evaporator unit 20. Because the refrigerant suction port 14b is directly opened into the first space 41, the refrigerant collection from the tubes 21 and the refrigerant suction into the ejector 14 can be performed by using a single tank space.
In the present embodiment, the first evaporator 15 and the second evaporator 18 are arranged adjacent to each other, and the downstream end portion of the ejector 14 is located adjacent to the second space 49 of the upper tank 15b of the first evaporator 15. Thus, even when the ejector 14 is incorporated into the second evaporator 18, the refrigerant passage structure from the outlet of the ejector 14 to the first evaporator 15 can be made simple and short.
The refrigerant flow in the entire evaporator unit 20 will be described with reference to
The refrigerant inlet 34 of the joint portion 33 is branched into the main passage 34a and the refrigerant branch passage 16 (16a). The branched refrigerant flowing into the main passage 34a from the refrigerant inlet 34 flows into the nozzle portion 14a of the ejector 14 to be decompressed by the nozzle portion 14a. The refrigerant flowing into the nozzle portion 14a of the ejector 14 is jetted from the jet port of the nozzle portion 14a to pass through the mixing portion 14c and the diffuser 14d. The refrigerant flowing out of the outlet 14e of the diffuser 14d of the ejector 14 flows into the second space 49 of the upper tank 15b of the first evaporator 15 as in the arrow “a” in
The refrigerant flowing from the diffuser 14d of the ejector 14 into the second space 49 of the upper tank 15b of the first evaporator 15 is distributed into the plural tubes 21 on the left side portion of the heat exchange core 15a, and flows downwardly in the tubes 21 as in the arrow “b” to be collected into the lower tank 15c of the first evaporator 15, as shown in
The refrigerant at the right side of the lower tank 15c passes through the plural tubes 21 on the right side of the heat exchange core 15a upwardly as shown by the arrow “d”, and flows into the first space 48 of the upper tank 15b. Then, as shown by the arrow “e” of
The refrigerant flowing into the refrigerant branch passage 16 (16a) of the joint portion 33 passes through the capillary tube 17a, and is decompressed by the capillary tube 17a to have a low pressure. The vapor-liquid two-phase refrigerant decompressed by the capillary tube 17a flows into the lower space 46 of the second space 42 of the upper tank 18b of the second evaporator 18, as shown by the allow “f” of
The refrigerant flowing into the lower space 46 of the second space 42 of the upper tank 18b flows downwardly in the plural tubes 21 on the left side of the heat exchanger core 18a as in the arrow “g” in
The refrigerant at the right side of the lower tank 18c passes through the plural tubes 21 on the right side of the heat exchange core 18a upwardly as shown by the arrow “d”, and flows into the first space 41 of the upper tank 18b. Because the refrigerant suction port 14b of the ejector 14 is made to directly communicate with the first space 41 of the upper tank 18b, the refrigerant in the first space 41 is drawn into the ejector 14 from the refrigerant suction port 14b.
Because the evaporator unit 20 has therein the above refrigerant passage structure, the single refrigerant inlet 34 is provided in the joint portion 33 to be used for the refrigerant passage structure of the evaporator unit 20, and the single refrigerant outlet 35 is provided in the evaporator unit 20 to be used for the refrigerant passage structure of the evaporator unit 20.
Now, an operation of the refrigerant cycle device having the evaporator unit 20 according to the first embodiment will be described. When the compressor 11 is driven by a vehicle engine, the high-temperature and high-pressure refrigerant compressed by and discharged from the compressor 11 flows into the radiator 12 where the high-temperature refrigerant is cooled and condensed by the outside air. The high-pressure refrigerant flowing out of the radiator 12 flows into the liquid receiver 12a within which the refrigerant is separated into liquid and vapor phases. The liquid refrigerant is derived from the liquid receiver 12a and passes through the expansion valve 13.
The expansion valve 13 adjusts the degree of opening of the valve to adjust a refrigerant flow amount, such that the superheat degree of the refrigerant on the refrigerant outlet side of the first evaporator 15 becomes a predetermined value, while the high-pressure refrigerant is decompressed. Here, the refrigerant on the refrigerant outlet side of the first evaporator 15 corresponds to the refrigerant to be drawn to the compressor 11. The refrigerant having passed through the expansion valve 13 flows into the refrigerant inlet 34 provided in the joint portion 34 of the evaporator unit 20. The refrigerant after passing through the expansion valve 13 has a middle pressure.
The refrigerant flowing into the evaporator unit 20 from the refrigerant inlet 34 is branched at the branch portion Z to be divided into the refrigerant stream (first stream) directed to the nozzle portion 14a of the ejector 14 through the main passage 34a of the joint portion 33, and the refrigerant stream (second stream) directed to the capillary throttle 17a (17) through the branch passage 16a (16) of the joint portion 33.
The refrigerant flowing into the ejector 14 is decompressed and expanded by the nozzle portion 14a. Thus, the pressure energy of the refrigerant is converted into the speed energy at the nozzle portion 14a, and the refrigerant is ejected from the jet port of the nozzle portion 14a at high speed. At this time, the pressure drop of the refrigerant around the jet port of the nozzle portion 14a causes to draw from the refrigerant suction port 14b, the refrigerant (vapor-phase refrigerant) having passed through the heat exchange core 18a of the second evaporator 18.
The refrigerant ejected from the nozzle portion 14a and the refrigerant drawn from the refrigerant suction port 14b are combined in the mixing portion 14c on the downstream side of the nozzle portion 14a to flow into the diffuser 14d. In the diffuser 14d, the speed (expansion) energy of the refrigerant is converted into the pressure energy by enlarging the passage sectional area, resulting in increased pressure of the refrigerant.
The refrigerant flowing out of the diffuser 14d of the ejector 14 flows through the refrigerant flow paths indicated by the arrows “a” to “e” in
The refrigerant flowing into the capillary tube 17a (i.e., throttle 17) is decompressed to become a low-pressure refrigerant (liquid-vapor two-phase refrigerant). The low-pressure refrigerant flows through the refrigerant flow paths in the second evaporator 18 as indicated by the arrows “f” to “i” of
According to the first embodiment, because the refrigerant downstream of the diffuser 14d of the ejector 14 is supplied to the first evaporator 15 while the refrigerant branched at the branch portion Z is supplied to the second evaporator 18 via the capillary tube 17a (i.e., throttle 17), cooling capacity can be obtained in both the first and second evaporators 15 and 18 at the same time. Therefore, the air cooled by both the first and second evaporators 15, 18 can be blown into a space to be cooled, thereby sufficiently cooling the space to be cooled.
The refrigerant evaporation pressure of the first evaporator 15 corresponds to the refrigerant pressure pressurized in the diffuser 14d. On the other hand, because the refrigerant outlet side of the second evaporator 18 is connected to the refrigerant suction port 14b of the ejector 14, the lowest pressure immediately after the decompression of the nozzle portion 14a can be applied to the second evaporator 18.
Accordingly, the refrigerant evaporation pressure (refrigerant evaporation temperature) of the second evaporator 18 can be made lower than the refrigerant evaporation pressure (refrigerant evaporation temperature) of the first evaporator 15. Furthermore, the first evaporator 15 having a relatively high refrigerant evaporation temperature is arranged upstream of the second evaporator 18 having a relatively low refrigerant evaporation temperature, in the flow direction A of air. Therefore, both a temperature difference between the refrigerant evaporation temperature and the temperature of the blown air in the first evaporator 15, and a temperature difference between the refrigerant evaporation temperature and the temperature of the blown air in the second evaporator 18 can be sufficiently obtained.
Therefore, cooling performance can be improved in both of the first evaporator 15 and the second evaporator 18, thereby improving cooling performance by using the combination of both the first and second evaporators 15, 18. Furthermore, because the refrigerant pressure is increased in the diffuser 14d of the ejector 14, the refrigerant suction pressure of the compressor 11 can be increased, thereby reducing the drive power of the compressor 11.
The refrigerant flow amount on the second evaporator 18 side can be adjusted independently by the capillary tube 17a (i.e., throttle 17) without directly depending on the function of the ejector 14, and the refrigerant flow amount flowing into the first evaporator 15 can be adjusted by a throttle characteristic of the nozzle portion 14a of the ejector 14. Thus, the refrigerant flow amounts flowing into the first and second evaporators 15 and 18 can be adjusted readily, to correspond to the respective heat loads of the first and second evaporators 15 and 18.
For a small cycle heat load, the difference between high and low pressures in the refrigerant cycle becomes small, and the input of the ejector 14 also becomes small. If the refrigerant flow amount passing through the second evaporator 18 depends on only the refrigerant suction ability of the ejector 14 at the small cycle heat load, it results in decreased input of the ejector 14, deterioration in the refrigerant suction ability of the ejector 14, and decrease in the refrigerant flow amount of the second evaporator 18 in order, making it difficult to secure the cooling performance of the second evaporator 18.
In contrast, in the embodiment, the refrigerant having passed through the expansion valve 13 is branched at the upstream part of the nozzle portion 14a of the ejector 14, and the branched refrigerant is drawn into the refrigerant suction port 14b through the branch passage 16, so that the refrigerant branch passage 16 is in a parallel connection relation to the ejector 14.
Thus, the refrigerant can be supplied to the branch passage 16, using not only the refrigerant suction ability of the ejector 14, but also the refrigerant suction and discharge abilities of the compressor 11. This can reduce the degree of decrease in the refrigerant flow amount on the second evaporator side 18 as compared with in the comparative cycle, even in the occurrence of phenomena, including decrease in input of the ejector 14, and deterioration in the refrigerant suction ability of the ejector 14. Accordingly, even under the condition of the low heat load, the cooling performance of the second evaporator 18 can be secured readily.
According to the first embodiment, the ejector 14, the first and second evaporators 15, 18 and the capillary tube 17a are assembled as a single unit structure, that is, as the evaporator unit 20, and the evaporator unit 20 is provided with the single refrigerant inlet 34 and the refrigerant outlet 35.
As a result, when the refrigerant cycle device 10 is mounted to the vehicle, the evaporator unit 20 provided with the various components (14, 15, 18, 17a) is connected as the whole such that the single refrigerant inlet 34 is connected to the refrigerant outlet side of the expansion valve 13 and the single refrigerant outlet 35 is connected to the refrigerant suction side of the compressor 11.
Furthermore, the ejector 14 is located within the tank portion (evaporator tank portion) of the first and second evaporators 15, 18, and the capillary tube 17a is integrated to the evaporator tank portion as shown in
Because the refrigerant outlet side of the second evaporator 18 is connected to the refrigerant suction port 14b of the ejector 14 without using a pipe, the evaporation pressure of the second evaporator 18 can be made lower by a pressure due to the pipe-caused pressure loss, thereby the cooling performance of the second evaporator 18 can be improved without increasing the compressor-consumed power.
Furthermore, because the ejector 14 is located in the evaporator tank part having a low-temperature condition, it is unnecessary to attach a heat insulating member to the ejector 14.
According to the fixing structure of the capillary tube 17a of the first embodiment, the following effects and advantages can be obtained.
(1) The two longitudinal end portions (i.e., inlet portion and outlet portion) of the capillary tube 17a are air-tightly bonded to respective connection portions. In addition, because at least one portion of the capillary tube 17a between the two longitudinal ends of the capillary tube 17a is fixed to the tank header 31, a vibration (vibration amplitude) of the capillary tube 17a due to the refrigerant flow can be reduced. Therefore, the vibration at the two longitudinal ends of the capillary tube 17a can be reduced, thereby preventing a crack from being generated at the connection portions of the two longitudinal ends of the capillary tube 17a.
(2) Because at least one portion of the capillary tube 17a between the two longitudinal ends of the capillary tube 17a is fixed to the tank header 31, a distance between adjacent support portions of the capillary tube 17a can be made shorter in the longitudinal direction of the capillary tube 17a.
Thus, the natural frequency of the capillary tube 17a becomes larger and is greatly different from the vibration frequency due to the refrigerant flow. As a result, the vibration of the capillary tube 17a can be reduced, thereby reducing noise due to vibration of the capillary tube 17a.
In a general configuration of the evaporator unit 20, the vibration frequency of the capillary tube 17a caused due to the refrigerant flow is almost in an area of 2-5 kHz which is easily heard by human. Furthermore, the outer diameter of the capillary tube 17a is generally equal to or smaller than 6 mm.
In the present embodiment, because the capillary tube 17a is fixed to the tank header 31 at distances equal to or smaller than 75 mm, so that the primary natural frequency is set to be larger than 5 kHz. Thus, the natural frequency of the capillary tube 17a can be separated from the vibration frequency due to the refrigerant flow, thereby reducing the vibration of the capillary tube 17a.
(3) In the present embodiment, the protrusion portions 31c are formed in the tank header 31, and the middle portion of the capillary tube 17a between the longitudinal two ends of the capillary tube 17a is fixed to the protrusion portions 31c at plural positions. Therefore, contact and fixing area between the middle portion of the capillary tube 17a and the tank header 31 is determined by the protrusion portions 31b provided on the tank header 31.
Accordingly, by suitably setting the dimension, the shape and the arrangement or the like of the protrusion portion(s) 31b, the vibration of the capillary tube 17a can be effectively reduced.
(4) In the present embodiment, the space between the protrusion portions 31c, which are offset from each other in the longitudinal direction of the capillary tube 17a, can be made slightly smaller when being viewed from the direction parallel to the tank longitudinal direction, than the outer diameter of the capillary tube 17a. Therefore, the capillary tube 17a can be press-fitted into the valley portion 31a between the protrusion portions 31c at both sides of the valley portion 31a.
Therefore, the portion of the capillary tube 17a between the longitudinal ends of the capillary tube 17a can be accurately fixed to the tank header 31, thereby reducing the vibration of the capillary tube 17a due to the refrigerant flow.
If the whole capillary tube 17a is fixed to the tank header 31, the capillary tube 17a is difficult to be bent, and thereby the capillary tube 17a may be difficult to be accurately fixed to the tank header 31.
In the present embodiment, the protrusion portions 31c are arranged in the tank header 31 by a predetermined distance in the tank longitudinal direction. Thus, if the capillary tube 17a is assembled to the tank header 31, the protrusion portions 31c are pressed to the outer peripheral surface of the capillary tube 17a, and thereby the capillary tube 17a is easily bent.
Thus, a spring back force (bending return force) is caused in the capillary tube 17a, and a friction force is caused between the capillary tube 17a and the protrusion portion 31c. Therefore, the capillary tube 17a can be accurately fixed to the tank header 31.
The dimension of the protrusion portion 31c in the tank longitudinal direction is set equal to or smaller than 30 mm, for example. In this case, the advantage of the protrusion portions 31c can be improved.
(5) In the present embodiment, the protrusion portions 31c are arranged in zigzag in the longitudinal direction so that the protrusion portions 31c at the two sides of the valley portion 31a are offset from each other in the tank longitudinal direction. Plural pairs of protrusion portions 31c opposite to each other in a tank minor direction perpendicular to the tank longitudinal direction may be provided in the tank header 31 in the tank longitudinal direction. However, in this case, when the capillary tube 17a is press-fitted to the tank header 31 between the protrusion portions 31c, the tank header 31 is easily deformed in the tank minor direction, and thereby it is difficult to accurately assemble the tank header 31 to a tank component such as the plate header 30. The strength of the tank header 31 may be increased in order to reduce its deformation. However, in this case, pressing force of the capillary tube 17a needs to be increased.
In contrast, in the present embodiment, because the protrusion portions 31c are arranged in zigzag in the longitudinal direction so that the protrusion portions 31c are offset from each other in the tank longitudinal direction. Thus, it can restrict the tank header 31 from being deformed in the tank minor direction when the capillary tube 17a is press-fitted to the tank header 31. Furthermore, the capillary tube 17a can be press-fitted between the protrusion portions 31c. Generally, the protrusion portions 31c are separated from each other in the tank longitudinal direction by a dimension equal to or larger than the outer diameter of the capillary tube 17a.
(6) In the present embodiment, because capillary tube 17a is fixed to the protrusion portions 31c of the tank header 31, the strength of the capillary tube 17a can be increased, and the vibration of the capillary tube 17a can be effectively reduced. When the brazing distance of the capillary tube 17a is equal to or smaller than 75 mm, the vibration reducing effect can be more improved.
(7) Because the protrusion portions 31c are formed by pressing out a part of the wall portion of the tank header 31 defining the tank space, the using material of the tank header 31 can be made smaller.
(8) In the present embodiment, the corner portion of the protrusion portion 31c is made to be a round shape. Therefore, the capillary tube 17a can be smoothly assembled to the tank header 31, and it can prevent the capillary tube 17a from being damaged while the capillary tube 17a is assembled to the tank header 31.
In the above-described first embodiment, the plural ribs 31b are provided in the tank header 31 as shown in
It should be understood that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made to the present embodiments as follows.
(1) In the above-described embodiments, the plural protrusion portions 31c are provided in the tank header 31 between the two longitudinal ends of the tank header 31. However, at least one of the protrusion portions 31c can be provided in the tank header 31 between the two longitudinal ends of the tank header 31. As one example, one of the protrusion portions 31c can be provided in the tank header 31 between the two longitudinal ends of the tank header 31.
Furthermore, the portion of the capillary tube 17a is not necessary to be fixed to all the protrusion portions 31c, and can be fixed to at least one of the protrusion portions 31c between the two longitudinal ends of the capillary tube 17a.
(2) In the above-described embodiments, the capillary tube 17a is arranged on an outer wall side of the tank header 31. However, the capillary tube 17a may be arranged on an inner wall side of the tank header 31.
The capillary tube 17a is not necessary to be fixed to the tank header 31. The capillary tube 17a may be fixed to a portion of the evaporators 15, 18 other than the tank header 31. For example, the capillary tube 17a may be fixed to a side surface of the heat exchange cores 15a, 18a, such that a portion of the capillary tube 17a between the two longitudinal ends of the capillary tube 17a contacts the side surface of the heat exchange cores 15a, 18a to be fixed to the side surface thereof.
(3) In the above-described embodiments, in integrally assembling respective components of the integrated unit 20, the components other than the ejector 14, that is, the first evaporator 15, the second evaporator 18, the joint portion 33, the capillary tube 17a, and the like are brazed integrally with each other. The integral assembly of these components can also be performed by various fixing means other than brazing, including screwing, caulking, welding, adhesion, and the like.
(4) Although in the above-described embodiments, the vapor-compression subcritical refrigerant cycle has been described in which the refrigerant is a flon-based one, an HC-based one, or the like, whose high pressure does not exceed the critical pressure, the invention may be applied to a vapor-compression supercritical refrigerant cycle which employs the refrigerant, such as carbon dioxide (CO2), whose high pressure exceeds the critical pressure.
In the supercritical cycle, only the refrigerant discharged by the compressor dissipates heat in the supercritical state at the radiator 12, and hence is not condensed. Thus, the liquid receiver 12a disposed on the high-pressure side cannot exhibit a liquid-vapor separation effect of the refrigerant, and a retention effect of the excessive liquid refrigerant. In this case, the supercritical cycle may have the structure including an accumulator at the outlet of the first evaporator 15 for serving as the low-pressure liquid-vapor separator.
(5) Although in the above-described embodiments, the throttle 17 is constructed by a fixed throttle hole such as the capillary tube 17a, the throttle 17 may be constructed by an electric control valve whose valve opening (i.e., an opening degree of a passage restriction) is adjustable by the electric actuator.
Although in the above-mentioned respective embodiments, the exemplary ejector 14 is a fixed ejector having the nozzle part 14a with the certain path area, the ejector 14 may be a variable ejector having a variable nozzle part whose path area is adjustable.
For example, the variable nozzle part may be a mechanism which is designed to adjust the path area by controlling the position of a needle inserted into a passage of the variable nozzle part using the electric actuator.
(6) Although in the above-described embodiments, the invention is applied to the refrigerant cycle device adapted for cooling the interior of the vehicle and for the freezer and refrigerator, both the first evaporator 15 whose refrigeration evaporation temperature is high and the second evaporator 18 whose refrigeration evaporation temperature is low may be used for cooling different areas inside the compartment of the vehicle (for example, an area on a front seat side inside the compartment of the vehicle, and an area on a back seat side therein).
Alternatively or additionally, both the first evaporator 15 whose refrigeration evaporation temperature is high and the second evaporator 18 whose refrigeration evaporation temperature is low may be used for cooling the freezer and refrigerator. That is, a refrigeration chamber of the freezer and refrigerator may be cooled by the first evaporator 15 whose refrigeration evaporation temperature is high, while a freezing chamber of the freezer and refrigerator may be cooled by the second evaporator 18 whose refrigeration evaporation temperature is low.
(7) The present invention can be applied to any type evaporator unit described in the related art and any type refrigerant cycle device without an ejector 14. That is, the present invention can be used for an evaporator unit without an ejector 14.
(8) It is apparent that although in the above-mentioned respective embodiments, the refrigerant cycle device for the vehicle has been described, the invention can be applied not only to the vehicle, but also to a fixed refrigeration cycle or the like in the same way.
(9) In the above-described embodiments, the ejector 14 is located in the upper tank 18b of the second evaporator 18, and the downstream side end 17d of the capillary tube 17a is located in the upper tank 18b of the second evaporator 18. However, the ejector 14 may be located in the upper tank 15b of the first evaporator 15, and the downstream side end 17d of the capillary tube 17a may be located in the upper tank 15b of the first evaporator 15.
(10) Although in the above embodiments, the thermal expansion valve 13 and the temperature sensing part 13a are separately provided from the evaporator unit for the refrigerant cycle device, the thermal expansion valve 13 and the temperature sensing part 13a may be integrally incorporated in the evaporator unit for the refrigerant cycle device. For example, a mechanism for accommodating the thermal expansion valve 13 and the temperature sensing part 13a in the joint portion 33 of the evaporator unit 20 can be employed. In this case, the refrigerant inlet 34 is positioned between the liquid receiver 12a and the thermal expansion valve 13, and the refrigerant outlet 26 is positioned between the compressor 11 and a passage part on which the temperature sensing part 13a is installed.
(11) Although in the above-described embodiments, the evaporator unit 20 is used as an interior heat exchanger, and the radiator 12 is used as the exterior heat exchanger. However, the evaporator unit 20 may be used as an exterior unit configured to absorb heat from outside air as a heat source, and the radiator 12 may be used as an interior heat exchanger for heating a fluid such as water or air, in a heat pump cycle.
Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-130890 | May 2008 | JP | national |
