a to 13e are cross-sectional views showing heat exchange tubes used in evaporators of Examples 2 to 5 and Comparative Example;
a to 18c are views showing a method of manufacturing the heat exchange tube of
An embodiment of the present invention will next be described in detail with reference to the drawings. The embodiment is implemented by applying a heat exchange tube according to the present invention to an evaporator of a car air conditioner using a chlorofluorocarbon-based refrigerant.
As shown in
The refrigerant inlet/outlet header tank 22 includes a refrigerant inlet header section 24 located on a side toward the front (downstream side with respect to the air flow direction), a refrigerant outlet header section 25 located on a side toward the rear (upstream side with respect to the air flow direction), and a connection section 26 which integrally connects the header sections 24 and 25. A refrigerant inlet pipe 27 made of aluminum is connected to the refrigerant inlet header section 24 of the refrigerant inlet/outlet header tank 22. A refrigerant outlet pipe 28 made of aluminum is connected to the refrigerant outlet header section 25.
The refrigerant turn header tank 23 includes a first intermediate header section 30 located on the side toward the front, a second intermediate header section 31 located on the side toward the rear, and a connection section 32 which integrally connects the header sections 30 and 31. The header sections 30 and 31 and the connection section 32 form a drain gutter 33.
The heat exchange core section 21 is configured as follows: heat exchange tube groups 35 are arranged in a plurality of; herein, two, rows in the front-rear direction, each heat exchange tube group 35 consisting of a plurality of heat exchange tubes 34 arranged in parallel at intervals in the left-right direction; corrugated fins 36 are disposed within corresponding air-passing clearances between the adjacent heat exchange tubes 34 of the heat exchange tube groups 35 and externally of the left-end and right-end heat exchange tubes 34 of the heat exchange tube groups 35 and are brazed to the corresponding heat exchange tubes 34; and side plates 37 made of aluminum are disposed externally of the left-end and right-end corrugated fins 36 and are brazed to the corresponding corrugated fins 36. Upper and lower ends of the heat exchange tubes 34 of the front heat exchange tube group 35 are connected to the refrigerant inlet header section 24 and the first intermediate header section 30, respectively, whereby the heat exchange tubes 34 form a forward refrigerant flow section. Upper and lower ends of the heat exchange tubes 34 of the rear heat exchange tube group 35 are connected to the refrigerant outlet header section 25 and the second intermediate header section 31, respectively, whereby the heat exchange tubes 34 form a return refrigerant flow section. The first intermediate header section 30, the second intermediate header section 31, and the heat exchange tubes 34 of the front and rear heat exchange tube groups 35 form a refrigerant circulation path for establishing communication between the refrigerant inlet header section 24 and the refrigerant outlet header section 25.
The heat exchange tube 34 is formed from a bare aluminum extrudate. As shown in
The heat exchange tube 34 satisfies a relation 0.558 ≦A≦1.235, where A is a value in pieces/mm obtained by dividing the number N of the refrigerant channels 34a by a width W of the heat exchange tube 34 as measured in the front-rear direction and is expressed by A=N/W. Also, the heat exchange tube 34 satisfies a relation 0.35≦Dh≦1.0, where Dh is an equivalent diameter in mm of the heat exchange tube 34. The heat exchange tube 34 satisfies one of or both of the above two requirements.
The corrugated fin 36 is made in a wavy form from an aluminum brazing sheet having a brazing material layer on each of opposite sides thereof. The corrugated fin 36 includes wave crest portions, wave trough portions, and flat horizontal connection portions each connecting together the wave crest portion and the wave trough portion. A plurality of louvers are formed at the connection portions in juxtaposition in the front-rear direction. The front and rear heat exchange tubes 34 which constitute the front and rear heat exchange tube groups 35 share the corresponding corrugated fins 36. The width of the corrugated fin 36 as measured in the front-rear direction is substantially equal to the span between the front end of the front heat exchange tube 34 and the rear end of the rear heat exchange tube 34. The wave crest portions and wave trough portions of the corrugated fin 36 are brazed to the front and rear heat exchange tubes. Notably, the front end of the corrugated fin 36 slightly projects frontward beyond the front end of the front heat exchange tube 34.
As shown in
The first member 38 includes a first header formation portion 44, which assumes a downward bulging form and forms a lower portion of the refrigerant inlet header section 24; a second header formation portion 45, which assumes a downward bulging form and forms a lower portion of the refrigerant outlet header section 25; and a connection wall 46, which connects a rear end portion of the first header formation portion 44 and a front end portion of the second header formation portion 45 and forms a lower portion of the connection section 26. A plurality of tube insertion holes 47 elongated in the front-rear direction are formed in the header formation portions 44 and 45 at intervals in the left-right direction. The tube insertion holes 47 of the header formation portion 44 and those of the header formation portion 45 are identical in position in the left-right direction. Upper end portions of the heat exchange tubes 34 of the front and rear heat exchange tube groups 35 of the heat exchange core section 21 are inserted into the respective tube insertion holes 47 of the first and second header formation portions 44 and 45 and are brazed to the first member 38 by utilization of the brazing material layers of the first member 38. Thus, the upper end portions of the heat exchange tubes 34 of the front heat exchange tube group 35 are connected to the refrigerant inlet header section 24 in a communicating condition, whereas the upper end portions of the heat exchange tubes 34 of the rear heat exchange tube group 35 are connected to the refrigerant outlet header section 25 in a communicating condition. A plurality of drain through-holes 48 elongated in the left-right direction are formed in the connection wall 46 at intervals in the left-right direction. Also, a plurality of fixation though-holes 49 are formed in the connection wall 46 at intervals in the left-right direction while being shifted from the drain through-holes 48.
The second member 39 includes a first header formation portion 51, which assumes an upward bulging form and forms an upper portion of the refrigerant inlet header section 24; a second header formation portion 52, which assumes an upward bulging form and forms an upper portion of the refrigerant outlet header section 25; and a connection wall 53, which connects a rear end portion of the first header formation portion 51 and a front end portion of the second header formation portion 52 and is brazed to the connection wall 46 of the first member 38 to form an upper portion of the connection section 26. The first header formation portion 51 has a horizontal intra-inlet-header-section flow-dividing control wall 51b, which integrally connects lower end portions of front and rear walls 51a of the first header formation portion 51 and vertically divides the interior of the refrigerant inlet header section 24 into two spaces 24A and 24B. The second header formation portion 52 has a horizontal intra-outlet-header-section flow-dividing control wall 52b, which is at the same level as that of the intra-inlet-header-section flow-dividing control wall 51b, integrally connects lower end portions of front and rear walls 52a of the second header formation portion 52, and vertically divides the interior of the refrigerant outlet header section 25 into two spaces 25A and 25B.
A cutout 50 is formed at the left end of the intra-inlet-header-section flow-dividing control wall 51b of the second member 39. The intra-inlet-header-section flow-dividing control wall 51b has flow-division-adjusting holes 60, which are formed in a through-hole form at a portion biased toward the cutout 50 and at a portion biased toward the right end. A plurality of oblong refrigerant passage holes 54A and 54B in a through-hole form and elongated in the left-right direction are formed in a rear region, excluding left and right end portions thereof, of the intra-outlet-header-section flow-dividing control wall 52b of the second member 39 at intervals in the left-right direction. The central oblong refrigerant passage hole 54A is shorter than the other oblong refrigerant passage holes 54B and is located between the adjacent heat exchange tubes 34.
A plurality of drain through-holes 55 elongated in the left-right direction are formed in the connection wall 53 of the second member 39 in alignment with the corresponding drain through-holes 48 of the first member 38. Also, a plurality of projections 56 are formed on the connection wall 53 in alignment with the corresponding fixation through-holes 49 of the first member 38 and are fitted into the corresponding fixation through-holes 49. The first member 38 and the second member 39 are assembled together as follows. The first and second members 38 and 39 are tentatively assembled together such that the projections 56 are tightly inserted into the corresponding fixation through-holes 49. In this tentatively assembled condition, by utilization of the brazing material layers of the first member 38, the first and second members 38 and 39 are assembled together such that front end portions of the first header formation portions 44 and 51, rear end portions of the second header formation portions 45 and 52, and the connection walls 46 and 53 are respectively brazed together.
The first header formation portion 44 of the first member 38 and the first header formation portion 51 of the second member 39 form a hollow inlet header section body 240 whose opposite ends are open. The second header formation portion 45 of the first member 38 and the second header formation portion 52 of the second member 39 form a hollow outlet header section body 250 whose opposite ends are open.
The left-hand closing member 41 is formed such that a front cap 41a for closing the left end opening of the inlet header section body 240 and a rear cap 41b for closing the left end opening of the outlet header section body 250 are integrated with each other via a connection portion 41c. The front cap 41a of the left-hand closing member 41 has an integrally formed rightward projecting portion 57 to be fitted into the inlet header section body 240. Similarly, the rear cap 41b has an integrally formed upper rightward-projecting portion 58 to be fitted into a space of the outlet header section body 250 located above the intra-outlet-header-section flow-dividing control wall 52b, and an integrally formed lower rightward-projecting portion 59 to be fitted into a space of the outlet header section body 250 located below the intra-outlet-header-section flow-dividing control wall 52b. The upper rightward-projecting portion 58 and the lower rightward-projecting portion 59 are vertically spaced apart from each other. Engagement fingers 61 projecting rightward are formed integrally with the left-hand closing member 41 at a connection portion between a front side edge and a top edge of the left-hand closing member 41, at a connection portion between the front side edge and a bottom edge, at a connection portion between a rear side edge and the top edge, and at a connection portion between the rear side edge and the bottom edge, respectively. The engagement fingers 61 are engaged with the first and second members 38 and 39. The left-hand closing member 41 is brazed to the first and second members 38 and 39 by utilization of its own brazing material layers. The front cap 41a of the left-hand closing member 41 closes the left end opening of the cutout 50 of the intra-inlet-header-section flow-dividing control wall 51b, thereby forming a communication hole 70 for establishing communication between the upper and lower spaces 24A and 24B of the inlet header section 24 at a left end portion of the inlet header section 24. In the present embodiment, the communication hole 70 is formed by means of closing the left end opening of the cutout 50 by the front cap 41a. However, instead of formation of a cutout, a through-hole may be formed at a left end portion of the intra-inlet-header-section flow-dividing control wall 51b so as to serve as a communication hole.
The right-hand closing member 42 is formed such that a front cap 42a for closing the right end opening of the inlet header section body 240 and a rear cap 42b for closing the right end opening of the outlet header section body 250 are integrated with each other via a connection portion 42c. The front cap 42a of the right-hand closing member 42 has an integrally formed upper leftward-projecting portion 62 to be fitted into a space of the inlet header section body 240 located above the intra-inlet-header-section flow-dividing control wall 51b, and an integrally formed lower leftward-projecting portion 80 to be fitted into a space of the inlet header section body 240 located below the intra-inlet-header-section flow-dividing control wall 51b. The upper leftward-projecting portion 62 and the lower leftward-projecting portion 80 are vertically spaced apart from each other. Similarly, the rear cap 42b has an integrally formed upper leftward-projecting portion 63 to be fitted into a space of the outlet header section body 250 located above the intra-outlet-header-section flow-dividing control wall 52b, and an integrally formed lower leftward-projecting portion 64 to be fitted into a space of the outlet header section body 250 located below the intra-outlet-header-section flow-dividing control wall 52b. The upper leftward-projecting portion 63 and the lower leftward-projecting portion 64 are vertically spaced apart from each other. A refrigerant inlet 66 is formed in a projecting end wall of the upper leftward-projecting portion 62 of the front cap 42a of the right-hand closing member 42. Similarly, a refrigerant outlet 67 is formed in a projecting end wall of the upper leftward-projecting portion 63 of the rear cap 42b. Engagement fingers 65 projecting leftward are formed integrally with the right-hand closing member 42 at a connection portion between a front side edge and a top edge of the right-hand closing member 42, at a connection portion between the front side edge and a bottom edge, at a connection portion between a rear side edge and the top edge, and at a connection portion between the rear side edge and the bottom edge, respectively. The engagement fingers 65 are engaged with the first and second members 38 and 39.
As shown in
The joint plate 43 has a short, cylindrical refrigerant inflow port 68 communicating with the refrigerant inlet 66 of the right-hand closing member 42, and a short, cylindrical refrigerant outflow port 69 communicating with the refrigerant outlet 67 of the right-hand closing member 42. Each of the refrigerant inflow port 68 and the refrigerant outflow port 69 includes a circular through-hole and a rightward-projecting short, cylindrical portion formed integrally around the circular through-hole.
A slit 4 extending in the vertical direction and adapted to prevent short circuit is formed in a portion of the joint plate 43 between the refrigerant inflow port 68 and the refrigerant outflow port 69. Also, generally trapezoidal through-holes 5 and 6 are formed in the portion of the joint plate 43 in such a manner as to be connected to the upper and lower ends, respectively, of the slit 4. Furthermore, a portion of the joint plate 43 located above the upper through-hole 5 and a portion of the joint plate 43 located below the lower through-hole 6 are bent in such a U-shaped fashion as to project leftward (toward the right-hand closing member 42), thereby forming first and second engagement female portions 7 and 8, respectively. The first engagement male portion 1 of the right-hand closing member 42 is inserted into the first engagement female portion 7 from underneath for engagement, and the second engagement male portion 2 of the right-hand closing member 42 is inserted into the second engagement female portion 8 from above for engagement, thereby preventing movement of the joint plate 43 in the left-right direction. The second engagement male portion 2 of the right-hand closing member 42 in a rightward projecting condition represented by the phantom line of
A diameter-reduced portion formed at one end portion of the refrigerant inlet pipe 27 is inserted into and brazed to the refrigerant inflow port 68 of the joint plate 43. Similarly, a diameter-reduced portion formed at one end portion of the refrigerant outlet pipe 28 is inserted into and brazed to the refrigerant outflow port 69 of the joint plate 43. Although unillustrated, an expansion valve attachment member is joined to the other end portions of the refrigerant inlet and outlet pipes 27 and 28 in such a manner as to face the ends of the pipes 27 and 28.
As shown in
The first member 73 includes a first header formation portion 78, which assumes an upward bulging form and forms an upper portion of the first intermediate header section 30; a second header formation portion 79, which assumes an upward bulging form and forms an upper portion of the second intermediate header section 31; and a connection wall 81, which connects a rear end portion of the first header formation portion 78 and a front end portion of the second header formation portion 79 and forms an upper portion of the connection section 32. Inclined walls 78a and 79a are provided at the front-rear-direction inside of the first and second header formation portions 78 and 79 and are inclined in such a manner as to fan out upward and in the front-rear direction. The inclined walls 78a and 79a and the connection wall 81 form a drain gutter 33 whose side surfaces are inclined in such a manner as to fan out upward and in the front-rear direction. A plurality of tube insertion holes 82 elongated in the front-rear direction are formed in the first and second header formation portions 78 and 79 at predetermined intervals in the left-right direction. The tube insertion holes 82 of the first header formation portion 78 and those of the second header formation portion 79 are identical in position in the left-right direction. End portions, located on a side toward the connection section 32, of the tube insertion holes 82; i.e., rear end portions of the tube insertion holes 82 of the first header formation portion 78 and front end portions of the tube insertion holes 82 of the second header formation portion 79, are located in the inclined walls 78a and 79a, respectively. Thus, the end portions, located on the side toward the connection section 32, of the tube insertion holes 82 are located in the side surfaces of the drain gutter 33. Drain grooves 83 are formed on the first and second header formation portions 78 and 79 on the front side of the corresponding tube insertion holes 82 of the first header formation portion 78 and on the rear side of the corresponding tube insertion holes 82 of the second header formation portion 79 in such a manner as to be connected to front end portions of the corresponding tube insertion holes 82 of the first header formation portion 78 and in such a manner as to be connected to rear end portions of the corresponding tube insertion holes 82 of the second header formation portion 79, as well as in such a manner that the bottom of each drain groove 83 extends gradually downward as the distance from the corresponding tube insertion hole 82 increases. Lower end portions of the heat exchange tubes 34 of the front and rear heat exchange tube groups 35 of the heat exchange core section 21 are inserted into the corresponding tube insertion holes 82 of the first and second header formation portions 78 and 79 and brazed to the first member 73 by utilization of the brazing material layers of the first member 73. Thus, the lower end portions of the heat exchange tubes 34 of the front heat exchange tube group 35 are connected to the first intermediate header section 30 in a communicating condition, whereas the lower end portions of the heat exchange tubes 34 of the rear heat exchange tube group 35 are connected to the second intermediate header section 31 in a communicating condition. A plurality of drain through-holes 84 elongated in the left-right direction are formed in the connection wall 81 of the first member 73 at intervals in the left-right direction. Also, a plurality of fixation though-holes 85 are formed in the connection wall 81 of the first member 73 at intervals in the left-right direction while being shifted from the drain through-holes 84. The first member 73 has the same shape as that of the first member 38 of the refrigerant inlet/outlet header tank 22. The first members 73 and 38 are disposed in a mirror image relation.
The second member 74 includes a first header formation portion 86, which assumes a downward bulging form and forms a lower portion of the first intermediate header section 30; a second header formation portion 87, which assumes a downward bulging form and forms a lower portion of the second intermediate header section 31; and a connection wall 88, which connects the first and second header formation portions 86 and 87 and is brazed to the connection wall 81 of the first member 73 to form the connection section 32. The second header formation portion 87 has a horizontal flow-dividing control wall 87b, which integrally connects upper end portions of front and rear walls 87a of the second header formation portion 87 and vertically divides the interior of the second intermediate header section 31 into two spaces 31A and 31B. A plurality of circular refrigerant passage holes 89 in a through-hole form are formed in a rear portion of the flow-dividing control wall 87b at intervals in the left-right direction. The distance between the adjacent circular refrigerant passage holes 89 increases gradually as the distance from the right end of the flow-dividing control wall 87b increases. Notably, the distance between the adjacent circular refrigerant passage holes 89 may be constant. A plurality of drain through-holes 91 elongated in the left-right direction are formed in the connection wall 88 of the second member 74 in alignment with the corresponding drain through-holes 84 of the first member 73. Also, a plurality of projections 92 projecting upward are formed on the connection wall 88 in alignment with the corresponding fixation through-holes 85 of the first member 73 and are fitted into the corresponding fixation through-holes 85. The first member 73 and the second member 74 are assembled together as follows. The first and second members 73 and 74 are tentatively assembled together such that the projections 92 are tightly inserted into the corresponding fixation through-holes 85. In this tentatively assembled condition, by utilization of the brazing material layers of the first member 73, the first and second members 73 and 74 are assembled together such that front end portions of the first header formation portions 78 and 86, rear end portions of the second header formation portions 79 and 87, and the connection walls 81 and 88 are respectively brazed together. The second member 74 has the same shape as that of the second member 39 of the refrigerant inlet/outlet header tank 22 except that the refrigerant passage holes 89 differ in shape and position from the refrigerant passage holes 54A and 54B and that the counterpart of the intra-inlet-header-section flow-dividing control wall 51b is absent. The second members 74 and 39 are disposed in a mirror image relation. The second members 74 and 39 are formed from the same extrudate.
The first header formation portion 78 of the first member 73 and the first header formation portion 86 of the second member 74 form a hollow, first intermediate header section body 300 whose opposite ends are open. The second header formation portion 79 of the first member 73 and the second header formation portion 87 of the second member 74 form a hollow, second intermediate header section body 310 whose opposite ends are open.
The left-hand closing member 75 is formed such that a front cap 75a for closing the left end opening of the first intermediate header section body 300 and a rear cap 75b for closing the left end opening of the second intermediate header section body 310 are integrated with each other. The front cap 75a has an integrally formed rightward projecting portion 93 to be fitted into the first intermediate header section body 300. Similarly, the rear cap 75b has an integrally formed upper rightward-projecting portion 94 to be fitted into a space of the second intermediate header section body 310 located above the flow-dividing control wall 87b, and an integrally formed lower rightward-projecting portion 95 to be fitted into a space of the second intermediate header section body 310 located below the flow-dividing control wall 87b. The upper rightward-projecting portion 94 and the lower rightward-projecting portion 95 are vertically spaced apart from each other. Engagement fingers 100 projecting rightward are formed integrally with the left-hand closing member 75 at a connection portion between a front side edge and a top edge of the left-hand closing member 75, at a connection portion between the front side edge and a bottom edge, at a connection portion between a rear side edge and the top edge, and at a connection portion between the rear side edge and the bottom edge, respectively. The engagement fingers 100 are engaged with the first and second members 73 and 74. The left-hand closing member 75 is brazed to the first and second members 73 and 74 by utilization of its own brazing material layers.
The right-hand closing member 76 is formed such that a front cap 76a for closing the right end opening of the first intermediate header section body 300 and a rear cap 76b for closing the right end opening of the second intermediate header section body 310 are integrated with each other. The front cap 76a has an integrally formed leftward projecting portion 96 to be fitted into the first intermediate header section body 300. Similarly, the rear cap 76b has an integrally formed upper leftward-projecting portion 97 to be fitted into a space of the second intermediate header section body 310 located above the flow-dividing control wall 87b, and an integrally formed lower leftward-projecting portion 98 to be fitted into a space of the second intermediate header section body 310 located below the flow-dividing control wall 87b. The upper leftward-projecting portion 97 and the lower leftward-projecting portion 98 are vertically spaced apart from each other. Engagement fingers 99 projecting leftward are formed integrally with the right-hand closing member 76 at a connection portion between a front side edge and a top edge of the right-hand closing member 76, at a connection portion between the front side edge and a bottom edge, at a connection portion between a rear side edge and the top edge, and at a connection portion between the rear side edge and the bottom edge, respectively. Also, engagement fingers 104 projecting rightward are formed integrally with the right-hand closing member 76 at front and rear end portions of the upper edge of the right-hand closing member 76. The rightward-projecting engagement fingers 104 are bent downward so as to be engaged with an upper edge portion of the communication member 77. The engagement finger 104 projecting rightward is formed integrally with the right-hand closing member 76 at a front-rear-direction central portion of the lower end of the right-hand closing member 76. The rightward-projecting engagement finger 104 is bent upward so as to be engaged with a lower edge portion of the communication member 77. A refrigerant outflow port 101 through which a refrigerant flows out from the first intermediate header section 30 is formed in a projecting end wall of the leftward projecting portion 96 of the front cap 76a of the right-hand closing member 76. Similarly, a refrigerant inflow port 102 through which the refrigerant flows into the lower space 31B of the second intermediate header section 31 located below the flow-dividing control wall 87b is formed in a projecting end wall of the lower leftward-projecting portion 98 of the rear cap 76b. Also, a guide portion 103 which is inclined or curved upward; in the present embodiment, curved upward, toward the interior of the second intermediate header section 31 is formed integrally with a lower portion of a circumferential portion of the refrigerant inflow port 102 of the lower leftward-projecting portion 98 of the rear cap 76b. The guide portion 103 guides upward (toward the flow-dividing control wall 87b) the refrigerant which flows into the lower space 31B of the second intermediate header section 31 located below the flow-dividing control wall 87b. The right-hand closing member 76 is brazed to the first and second members 73 and 74 by utilization of its own brazing material layers.
The communication member 77 is formed from an aluminum bear material by press work and assumes, as viewed from the right, a plate-like form identical with that of the right-hand closing member 76. A peripheral edge portion of the communication member 77 is brazed to the outer surface of the right-hand closing member 76 by utilization of the brazing material layers of the right-hand closing member 76. An outward bulging portion 105 is formed on the communication member 77 so as to establish communication between the refrigerant outflow port 101 and the refrigerant inflow port 102 of the right-hand closing member 76. The interior of the outward bulging portion 105 serves as a communication channel for establishing communication between the refrigerant outflow port 101 and the refrigerant inflow port 102 of the right-hand closing member 76. Cutouts 106 are formed in the communication member 77 at front and rear end portions of the upper edge of the communication member 77 and at a front-rear-direction central portion of the lower edge, respectively. The engagement fingers 104 of the right-hand closing member 76 are fitted into the corresponding cutouts 106.
In manufacture of the evaporator 20, component members thereof excluding the refrigerant inlet pipe 27 and the refrigerant outlet pipe 28 are provisionally assembled together, and the resultant assembly is subjected to batch brazing.
The evaporator 20, together with a fixed-capacity-type compressor and a condenser serving as a refrigerant cooler, constitutes a refrigeration cycle which uses a chlorofluorocarbon-based refrigerant. This refrigeration cycle is installed in a vehicle, such as an automobile, as a car air conditioner.
In the evaporator 20 described above, while the fixed-capacity-type compressor is ON, a two-phase refrigerant of vapor-liquid phase having passed through a compressor, a condenser, and an expansion valve enters the upper space 24A of the refrigerant inlet header section 24 of the refrigerant inlet/outlet header tank 22 from the refrigerant inlet pipe 27 through the refrigerant inflow port 68 of the joint plate 43 and the refrigerant inlet 66 of the front cap 42a of the right-hand closing member 42. The refrigerant having entered the upper space 24A of the refrigerant inlet header section 24 flows leftward and enters the lower space 24B through the communication hole 70 and through the flow-division-adjusting holes 60.
The refrigerant having entered the lower space 24B dividedly flows into the refrigerant channels 34a of the heat exchange tubes 34 of the front heat exchange tube group 35. The refrigerant having flown into the refrigerant channels 34a of the heat exchange tube 34 flows downward through the refrigerant channels 34a and enters the first intermediate header section 30 of the refrigerant turn header tank 23. The refrigerant having entered the first intermediate header section 30 flows rightward and then flows through the refrigerant outflow port 101 of the front cap 76a of the right-hand closing member 76, the communication channel in the outward bulging portion 105 of the communication member 77, and the refrigerant inflow port 102 of the rear cap 76b, thereby turning its flow direction and entering the lower space 31B of the second intermediate header section 31.
The refrigerant having entered the lower space 31B of the second intermediate header section 31 flows leftward; enters the upper space 31A through the circular refrigerant passage holes 89 of the flow-dividing control wall 87b; and dividedly flows into the refrigerant channels 34a of all the rear heat exchange tubes 34. At the time of entry of the refrigerant into the lower space 31B, while being guided by the guide portion 103, the refrigerant flows leftward in an obliquely upward direction; i.e., into the interior of the lower space 31B while being biased toward the flow-dividing control wall 87b. By virtue of this combined with the feature that the distance between the adjacent circular refrigerant passage holes 89 formed in the flow-dividing control wall 87b increases as the distance from the right end of the flow-dividing control wall 87b increases, the refrigerant which flows into the upper space 31A through the refrigerant passage holes 89 is distributed uniformly in the left-right direction as opposed to the case where the guide portion 103 is not provided. Accordingly, the refrigerant flows into the heat exchange tubes 34 connected to the second intermediate header section 31 easily in a uniformly divided condition; thus, nonuniform distribution of the refrigerant in the heat exchange core section 21 becomes unlikely to arise. Therefore, the temperature of air having passed through the heat exchange core section 21 is homogenized, thereby improving heat exchange performance.
The refrigerant having flown into the refrigerant channels 34a of the heat exchange tubes 34 flows upward, in opposition to the previous flow direction, through the refrigerant channels 34a; enters the lower space 25B of the refrigerant outlet header section 25; and then enters the upper space 25A through the oblong refrigerant passage holes 54A and 54B of the intra-outlet-header-section flow-dividing control wall 52b.
Next, the refrigerant having entered the upper space 25A of the refrigerant outlet header section 25 flows out into the refrigerant outlet pipe 28 through the refrigerant outlet 67 of the rear cap 42b of the right-hand closing member 42 and through the refrigerant outflow port 69 of the joint plate 43.
While flowing through the refrigerant channels 34a of the front heat exchange tubes 34 and through the refrigerant channels 34a of the rear heat exchange tubes 34, the refrigerant is subjected to heat exchange with air flowing through the air-passing clearances of the heat exchange core section 21. Then, the refrigerant flows out from the evaporator 20 in a vapor phase.
When the fixed-capacity-type compressor is turned OFF, the liquid-phase refrigerant remaining within the refrigerant channels 34a of the heat exchange tubes 34 is effectively retained within the refrigerant channels 34a by virtue of the capillary effect. This prevents outflow of the liquid-phase refrigerant from the refrigerant channels 34a of the heat exchange tubes 34 in a short period of time. Additionally, even after the compressor is turned OFF, while the liquid-phase refrigerant remains within the refrigerant channels 34a of the heat exchange tubes 34 of the evaporator 20, heat exchange continues between the remaining liquid-phase refrigerant and air passing through the evaporator 20, so that an abrupt increase in discharge air temperature can be restrained.
Next, examples of an evaporator according to the present invention, together with a comparative example, will be described.
The evaporator 20 was prepared which employed the heat exchange tubes 34 each having the configuration shown in
An evaporator was prepared which employed heat exchange tubes 34A each having the configuration shown in
An evaporator was prepared which employed heat exchange tubes 34B each having the configuration shown in
An evaporator was prepared which employed heat exchange tubes 34C each having the configuration shown in
An evaporator was prepared which employed heat exchange tubes 34D each having the configuration shown in
An evaporator was prepared which employed heat exchange tubes 34E each having the configuration shown in
The heat exchange tubes 34, 34A, 34B, 34C, 34D, and 34E used in the evaporators of Examples 1 to 5 and Comparative Example have a width W of 17 mm as measured in the front-rear direction and a tube height H, which is a thickness as measured in the left-right direction, of 1.4 mm. Table 1 shows the following characteristic values of the heat exchange tubes 34, 34A, 34B, 34C, 34D, and 34E: the total cross-sectional area of the plurality of refrigerant channels 34a; the total cross-sectional, perimetric length of the plurality of refrigerant channels 34a; the equivalent diameter Dh; and the value A in pieces/mm obtained by dividing the number N of the refrigerant channels 34a by the width W as measured in the front-rear direction (A=N/W).
The evaporators of Examples 1 to 5 and Comparative Example were incorporated into a refrigeration cycle and were examined for cooling performance while a fixed-capacity-type compressor was ON. Also, the evaporators were examined for the amount of a liquid-phase refrigerant remaining within the refrigerant channels 34a of the heat exchange tubes 34, 34A, 34B, 34C, 34D, and 34E. Furthermore, the evaporators were examined for time which elapsed after the elapse of 5 seconds after the fixed-capacity-type compressor was turned OFF, until the liquid-phase refrigerant remaining within the refrigerant channels 34a of the heat exchange tubes 34, 34A, 34B, 34C, 34D, and 34E evaporated. Table 1 shows the results of the examinations, and
As is apparent from Table 1 and
In
The front side wall 133 has a dual structure and includes an outer side-wall-forming elongated projection 136 which is integrally formed with the front side end of the left wall 131 in a rightward raised condition and extends along the entire height of the heat exchange tube 130; an inner side-wall-forming elongated projection 137 which is located inside the outer side-wall-forming elongated projection 136 and is integrally formed with the left wall 131 in a rightward raised condition; and an inner side-wall-forming elongated projection 138 which is integrally formed with the front side end of the right wall 132 in a leftward raised condition. The front side wall 133 has flat inner and outer surfaces. The outer side-wall-forming elongated projection 136 is brazed to the inner side-wall-forming elongated projections 137 and 138 and to the right wall 132 while a right end portion thereof is engaged with a front side edge portion of the right surface of the right wall 132. The inner side-wall-forming elongated projections 137 and 138 are brazed together while butting against each other. The rear side wall 134 is integrally formed with the left and right walls 131 and 132. The rear side wall 134 has flat inner and outer surfaces. A projection 138a is integrally formed on the tip end face of the inner side-wall-forming elongated projection 138 of the right wall 132 and extends in the longitudinal direction of the inner side-wall-forming elongated projection 138 along the entire length of the inner side-wall-forming elongated projection 138. A groove 137a is formed on the tip end face of the inner side-wall-forming elongated projection 137 of the left wall 131 and extends in the longitudinal direction of the inner side-wall-forming elongated projection 137 along the entire length of the inner side-wall-forming elongated projection 137. The projection 138a is press-fitted into the groove 137a.
The partition walls 135 are formed such that partition-wall-forming elongated projections 140 and 141, which are integrally formed with the left wall 131 in a rightward raised condition, and partition-wall-forming elongated projections 142 and 143, which are integrally formed with the right wall 132 in a leftward raised condition, are brazed together while the partition-wall-forming elongate projections 140 and 141 butt against the partition-wall-forming elongated projections 143 and 142, respectively. The left wall 131 has the partition-wall-forming elongated projections 140 and 141, which are of different projecting heights and are arranged alternately in the front-rear direction. The right wall 132 has the partition-wall-forming elongated projections 142 and 143, which are of different projecting heights and are arranged alternately in the front-rear direction. The partition-wall-forming elongated projections 140 of a high projecting height of the left wall 131 and the respective partition-wall-forming elongated projections 143 of a low projecting height of the right wall 132 are brazed together. The partition-wall-forming elongated projections 141 of a low projecting height of the left wall 131 and the respective partition-wall-forming elongated projections 142 of a high projecting height of the right wall 132 are brazed together. Hereinafter, the partition-wall-forming elongated projections 140 and 142 of a high projecting height of the left and right walls 131 and 132 are called the first partition-wall-forming elongated projections. Similarly, the partition-wall-forming elongated projections 141 and 143 of a low projecting height of the left and right walls 131 and 132 are called the second partition-wall-forming elongated projections. A groove 144 (145) is formed on the tip end face of the second partition-wall-forming elongated projection 141 (143) of the left wall 131 (right wall 132) and extends in the longitudinal direction of the second partition-wall-forming elongated projection 141 (143) along the entire length of the second partition-wall-forming elongated projection 141 (143). A tip end portion of the first partition-wall-forming elongated projection 142 (140) of the right wall 132 (left wall 131) is fitted into the groove 144 (145) of the second partition-wall-forming elongated projection 141 (143) of the left wall 131 (right wall 132). While tip end portions of the first partition-wall-forming elongated projections 140 and 142 of the left and right walls 131 and 132 are fitted into the respective grooves 145 and 144, the partition-wall-forming elongated projections 140 and 143 are brazed together, and the partition-wall-forming elongated projections 141 and 142 are brazed together.
Also, in the heat exchange tube 130 shown in
The heat exchange tube 130 is manufactured by use of a tube-forming metal sheet 150 as shown in
The inner side-wall-forming elongated projections 137 and 138 and the partition-wall-forming elongated projections 140, 141, 142, and 143 are integrally formed, by rolling, on one side of the aluminum brazing sheet whose opposite sides are clad with respective brazing materials, whereby a brazing material layer (not shown) is formed on the opposite side surfaces and tip end faces of the inner side-wall-forming elongated projections 137 and 138 and the partition-wall-forming elongated projections 140, 141, 142, and 143; on the inner peripheral surfaces of the grooves 144 and 145 of the second partition-wall-forming elongated projections 141 and 143; and on the left and right surfaces of the left-wall-forming and right-wall-forming portions 151 and 152 and the outer side-wall-forming-elongated-projection forming portion 154.
The tube-forming metal sheet 150 is gradually folded at opposite side edges of the connection portion 153 by a roll forming process (see
Next, the outer side-wall-forming-elongated-projection forming portion 154 is folded along the outer surfaces of the inner side-wall-forming elongated projections 137 and 138, and a tip end portion thereof is deformed so as to be engaged with the right-wall-forming portion 152, thereby yielding a folded member 155 (see
Subsequently, the folded member 155 is heated at a predetermined temperature so as to braze together tip end portions of the inner side-wall-forming elongated projections 137 and 138; to braze together tip end portions of the first and second partition-wall-forming elongated projections 140 and 143; to braze together tip end portions of the first and second partition-wall-forming elongated projections 142 and 141; and to braze the outer side-wall-forming-elongated-projection forming portion 154 to the inner side-wall-forming elongated projections 137 and 138 and to the right-wall-forming portion 152. Thus is manufactured the heat exchange tube 130.
In
The front side wall 163 has a dual structure and includes an outer side-wall-forming elongated projection 166 which is integrally formed with the front side end of the left wall 161 in a rightward raised condition and extends along the entire height of the heat exchange tube 160; and an inner side-wall-forming elongated projection 167 which is located inside the outer side-wall-forming elongated projection 166 and is integrally formed with the front side end of the right wall 162 in a leftward raised condition and extends along the entire height of the heat exchange tube 160. The rear side wall 164 has a dual structure and includes an outer side-wall-forming elongated projection 168 which is integrally formed with the rear side end of the right wall 162 in a leftward raised condition and extends along the entire height of the heat exchange tube 160; and an inner side-wall-forming elongated projection 169 which is located inside the outer side-wall-forming elongated projection 168 and is integrally formed with the right side end of the left wall 161 in a rightward raised condition and extends along the entire height of the heat exchange tube 160. Each of the front and rear side walls 163 and 164 has such an arcuate cross section that a central portion with respect to the left-right direction projects outward. The outer side-wall-forming elongated projections 166 and 168 of the front and rear side walls 163 and 164 are brazed to the inner side-wall-forming elongated projections 167 and 169.
A corrugated partition-wall-forming portion 170 is integrally formed between a tip end portion of the inner side-wall-forming elongated projection 167 of the front wall 163 and a tip end portion of the inner side-wall-forming elongated projection 169 of the rear wall 164. The partition-wall-forming portion 170 includes wave crest portions 171 brazed to the left wall 161, wave trough portions 172 brazed to the right wall 162, and connection portions 173 connecting together the wave crest portions 171 and the wave trough portions 172 and serving as the partition walls 165.
Although unillustrated, the heat exchange tube 160 is manufactured as follows: a tube-forming metal sheet formed from an aluminum brazing sheet having a brazing material layer on each of opposite sides is bent to yield a folded member, and the folded member is subjected to brazing so as to simultaneously braze together the outer side-wall-forming elongated projections 166 and 168 and the inner side-wall-forming elongated projections 167 and 169, respectively, of the front and rear side walls 163 and 164, the wave crest portions 171 of the partition-wall-forming portion 170 and the left wall 161, and the wave trough portions 172 of the partition-wall-forming portion 170 and the right wall 162.
In the above-described embodiment, the evaporator according to the present invention is applied to a car air conditioner which uses a chlorofluorocarbon-based refrigerant. However, the present invention is not limited thereto. The present invention may be applied to an evaporator of a car air conditioner which is used in a vehicle, for example, in an automobile and which includes a compressor, a gas cooler serving as a refrigerant cooler, an intermediate heat exchanger, an expansion valve, and an evaporator and uses a supercritical refrigerant such as CO2.
Number | Date | Country | Kind |
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2006-149550 | May 2006 | JP | national |