Accumulator with inlet diffuser\diverter

Abstract

An accumulator for use in a motor vehicle air conditioning system. The accumulator comprises an accumulator housing, an outlet fluid pipe assembly and an inlet fluid pipe assembly. The accumulator housing has a top wall, a bottom wall and a side wall connecting the top wall to the bottom wall. The outlet fluid pipe assembly has an inlet end. The inlet fluid pipe assembly includes a tubular first portion and a diverter/diffusing portion configured to direct refrigerant flowing through the first portion towards the sidewall and downwardly away from the top wall of the accumulator housing. The first tubular portion has an axis offset from the inlet end of the outlet fluid pipe assembly.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an accumulator for use in motor vehicle air conditioning systems. More specifically, it relates to the fluid inlet pipe assembly used in such accumulators.

[0002] In air conditioning systems such as those for motor vehicle use, an accumulator is normally connected between the evaporator and the suction side of the compressor to prevent liquid refrigerant from entering the compressor while permitting vaporous refrigerant to pass. This separation of liquid refrigerant, as well as its eventual return into vaporous form, is accomplished by either a straight or U-shaped fluid outlet pipe whose inlet end is positioned high in the accumulator so as to be open to receive the vaporous refrigerant flow delivered from the evaporator. To separate the liquid refrigerant from the vaporous refrigerant, a baffle may be mounted either on the ceiling of the accumulator housing or directly on the inlet end of the fluid outlet pipe, as disclosed in U.S. Pat. No. 4,111,005. Alternatively, the baffle, as a separate part, may be eliminated by forming the inlet end of the fluid outlet pipe with a trumpet shape portion located closely adjacent to the ceiling of the accumulator housing, as disclosed in U.S. Pat. No. 5,179,844.

[0003] The mixture of liquid and vaporous refrigerant enters the accumulator through a fluid inlet pipe assembly. The fluid inlet pipe assembly may be attached to the side wall of the accumulator housing, as disclosed in U.S. Pat. Nos. 4,111,005 and 5,179,844, or alternatively the fluid inlet pipe assembly may be attached the top wall of the accumulator housing to reduce the size of the accumulator housing. However, this arrangement of attaching the fluid inlet pipe assembly to the top wall of the accumulator housing has been found to cause excessive internal agitation; thus increasing the risk of a mixture of liquid and vaporous refrigerant passing through the outlet pipe to the compressor, leading to inefficient operation of the air conditioning system and risk of damage to the compressor. To reduce agitation of and foaming of refrigerant into the interior of the accumulator, U.S. Pat. No. 6,363,742 discloses the use of an inverted T-shaped inlet fluid pipe assembly having two outlet ends facing a portion of the side wall to divert and reduce the energy of the fluid as the fluid enters the accumulator. While such an inverted T-shaped inlet fluid pipe assembly is effective in diverting and reducing the energy of the fluid, it significantly increases the packaging requirement of the inlet fluid pipe assembly inside the accumulator housing and increases the cost associated with forming a pipe with two ends extending between opposite sides of the side wall. Even though the '742 patent discloses an alternative arrangement of an inlet fluid pipe assembly having a single open end such that the inlet pipe assembly is substantially L-shaped inside the accumulator housing, the '742 patent does not teach or suggest how the L-shaped inlet pipe may be capable of diffusing the liquid and vaporous mixture exiting the single open end.

[0004] In addition to turbulent flow caused by the flow of refrigerant out of the inlet fluid pipe assembly, turbulent flow may also be caused by the refrigerant flowing through the flow passage defined within the inlet fitting. Typical, to form a fluid path in the inlet fitting having a bend, two straight fluid passages are formed in the inlet fitting, wherein the two fluid passages intersects to connect the two straight fluid passages. The straight fluid passages are normally formed by drilling holes with cutters having sharp conical shaped drill tips. To assure that the intersection of the cross-drilled holes provide a sufficient size opening to connect the holes, each hole is drilled such that circumferential portion of the cutter extends at least to the intersection of the cross-drilled holes. However, due to the conical terminal ends of the holes created by the drill tips, sharp edges are often present at the intersection of the cross-drilled holes causing turbulence and pressure drop in the inlet flow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a sectional view of an accumulator with a typical prior art fluid inlet pipe assembly attached to the top wall of the accumulator housing, along with the other components of an air conditioning system schematically illustrated;

[0006] FIG. 2 is a sectional view of an accumulator with a prior art inverted T-shape fluid inlet pipe assembly attached to the top wall of the accumulator housing;

[0007] FIG. 3 is a sectional view of an accumulator with a first embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0008] FIG. 4 is a perspective view of the fluid inlet pipe assembly of FIG. 3;

[0009] FIG. 5 is a sectional view of an accumulator with a second embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0010] FIG. 6 is a sectional view of an accumulator with a third embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0011] FIG. 7 is a perspective view of the fluid inlet pipe assembly of FIG. 6;

[0012] FIG. 8 is a sectional view of an accumulator with a fourth embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0013] FIG. 9 is a perspective view of the diverter/diffuser assembly of FIG. 8;

[0014] FIG. 10 is a sectional view of an accumulator with a fifth embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0015] FIG. 11 is a sectional view of an accumulator with a sixth embodiment of a fluid inlet pipe assembly in accordance to the present invention;

[0016] FIG. 12 is a front view of a typical prior art inlet fitting;

[0017] FIG. 13 is a sectional view of the prior art inlet fitting of FIG. 12 as taken along line 13-13;

[0018] FIG. 14 is a front view of an inlet fitting in accordance a second aspect of the present invention; and

[0019] FIG. 15 is a sectional view of the inlet fitting of FIG. 14 as taken along line 15-15.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] A sectional view of an accumulator for a motor vehicle air conditioning system 10, with a typical prior art fluid inlet pipe assembly attached to the top wall of the accumulator housing, is illustrated in FIG. 1, along with the other components of the air conditioning system schematically illustrated. The air conditioning system 10 includes an accumulator 12 for separating the liquid refrigerant from the vaporous refrigerant, a compressor 14 for pumping and pressurizing the vaporous refrigerant, an outside heat exchanger or condenser 16 located outside the passenger compartment to cool and liquify the hot vaporous refrigerant from the compressor 14, an expander 18 to lower the pressure of the liquid refrigerant, and an inside heat exchanger or evaporator 20 which absorbs heat from the air passing between the tubes of the evaporator 20, thus cooling the air flowing into the passenger compartment. The air condition system 10 is a closed loop system wherein the refrigerant flows from the accumulator 12, to the compressor 14, to the condenser 16, to the expander 18, to the evaporator 20, and back to the accumulator 12.

[0021] The accumulator 12 as illustrated in FIG. 1 includes a permanently assembled housing 22 comprised of upper and lower portions 24, 26 which are each normally closed at one end and open at the other end, and are adapted to be telescopically received together and joined at their open ends. The upper end of the upper portion 24 defines the top wall 28 of the accumulator housing 22. The inside surface of the top wall 28 defines the ceiling 30 of the interior of the accumulator housing 22. The bottom end of the bottom portion 26 defines the bottom wall 32 of the accumulator housing 22. The cylindrical walls of the upper portion 24 and the lower portion 26 define the side wall 34 of the accumulator housing 22 connecting the top wall 28 to the bottom wall 32. An inlet fitting 36, by which the accumulator 12 is connected to the evaporator 20, is attached to the top wall 28 of the accumulator housing 22. An outlet fitting 38, by which the accumulator 12 is attached to the compressor 14, is attached to the side wall 34 of the accumulator housing 22.

[0022] Located within the interior of the accumulator housing 22, an inlet fluid pipe assembly 40 is attached to the inlet fitting 36 and a U-shaped outlet fluid pipe assembly 60 is attached to the outlet fitting 38. The inlet fluid pipe assembly 40 includes a straight tubular vertical portion 42 having an outlet end 48 located a given distance from the ceiling 30 of the accumulator housing 22. The outlet end 48 of the vertical portion 42 is directed downwardly toward the bottom wall 32 of the accumulator housing 22. The U-shaped outlet fluid pipe assembly 60 includes an outlet end 62 that is press fitted into the outlet fitting 38. The outlet fluid pipe assembly 60 further includes a downward leg 64 that extends from the outlet fitting 38 to a point adjacent to the bottom wall 32, a return bend 66 that makes a turn near the bottom wall 32 of the accumulator housing 22, and upward leg 68 that extends upwardly and terminates at an inlet end 70 adjacent the ceiling 30 of the housing 22. The inlet end 70 of the outlet fluid pipe assembly 60 is formed with a trumpet or flared shape portion 72 that is located above the outlet end 48 of the inlet fluid pipe 40 with its rim 74 close the ceiling 30 of the accumulator housing 22.

[0023] FIG. 2 illustrates an accumulator 112 with a prior art inverted T-shaped fluid inlet pipe assembly 140 attached to the top wall 128 of the accumulator housing 122, as disclosed in U.S. Pat. No. 6,363,742. The inlet pipe assembly 140 includes a vertical portion 142 and a horizontal portion 146. One end of the vertical portion 142 extends through the top wall 128 of the accumulator housing 122 and the other end of the vertical portion 142 is attached to middle of the horizontal portion 146. The horizontal portion 146 can be viewed as two horizontal sub-portions 146a, 146b extending radially outwardly at opposite directions from the end of the vertical portion 142 at 90 degree angles. Since the axis of the vertical portion 142 of the inlet pipe assembly 140 is approximately parallel with the axis of the accumulator housing 122, the axis of the horizontal portion 146 is approximately 90 degrees to the side wall 134 of the accumulator housing 122.

[0024] FIGS. 3 and 4 illustrate a first embodiment of a fluid inlet pipe assembly 240 according to the present invention. The fluid inlet pipe assembly 240 is attached to the top wall 228 of the accumulator housing 222. The fluid inlet pipe assembly includes a tubular vertical portion 242, a tubular diverter/diffuser portion 246 and a curved portion 244 connecting the vertical portion 242 to the diverter/diffuser portion 246. The vertical portion 242 has an axis approximately parallel with the axis of the accumulator housing 222. To allow the inlet end 270 of the outlet pipe assembly 260 to be located near the ceiling of the accumulator housing 222, the axis of the vertical portion 242 is offset from the inlet end 270 of the outlet pipe assembly 260. In other words, the axis of the vertical portion 242 does not intersect the inlet end 270 of the outlet pipe assembly 260. Such an arrangement allows the inlet end 270 of the outlet pipe assembly 260 to be located adjacent to the vertical portion 242 of the inlet pipe 240, rather than, below the vertical portion 242 of the inlet pipe 240.

[0025] The axis of the divert/diffuser portion 246 is at an angle greater than 0 degree and less than 90 degrees from the axis of vertical portion. The angle α from the axis of the diverter/diffuser portion 246 to the axis of the vertical portion 242 is preferably between 10 degrees to 80 degrees, and more preferably between 15 degrees to 45 degrees. The embodiment of FIG. 3 illustrates the angle α from the axis of the diverter/diffuser portion 246 to the axis of the vertical portion 242 at approximately 30 degrees. By bending the pipe for forming the inlet pipe assembly 240 at an angle less than 90 degrees, the flow of the inlet refrigerant mixture is directed towards the side wall 234 and dowardly away from the ceiling 230 of the accumulator housing 222. By directing the inlet refrigerant mixture towards the side wall 234, the liquid refrigerant is able to flow downwardly along the side wall 234 to the bottom sump portion of the accumulator housing 222. By directing the inlet refrigerant mixture downwardly away from the ceiling 230 of the accumulator housing 222, the possible of the inlet refrigerant unintentionally entering the inlet end 270 of the outlet fluid pipe assembly 260 is reduced.

[0026] The terminal end of the diverter/diffuser portion 246 defines the outlet end 248 of the fluid inlet pipe assembly 240. The outlet end 248 of the fluid inlet pipe assembly 240 is formed by making an angular cut across the diverter/diffuser portion 246 such that the plane of the cut is approximately parallel of the axis of the vertical portion 242. Since the axis of the diverter/diffuser portion 246 is at an angle less than 90 degrees from the axis of the vertical portion 242 and the plane of the cut is made approximately parallel of the axis of the vertical portion 242, the cut will be at an angle other than 90 degrees from the axis of the diverter/diffuser portion 246. With the cut at angle other than 90 degrees from the axis of the diverter/diffuser portion 246, the outlet end 248 of the fluid inlet pipe assembly 240 has a cross-sectional area greater than the average cross-sectional area perpendicular to the axis of the vertical portion 242. With the outlet end 248 having a greater cross-sectional area, the outlet end 248 is able to act as a diffuser diffusing the flow of refrigerant coming out the outlet end 248; thus, reducing or preventing turbulent flow of refrigerant. Another advantage of cutting the diverter/diffuser portion 246 at a plane approximately equal to the axis of the vertical portion 242 of the inlet pipe assembly 240 is that since the axis of the vertical portion 242 of the inlet pipe assembly 240 is approximate parallel to the axis of the accumulator housing 222, the distances from the edges of the outlet end 248 to the side wall 234 are approximately equal. The approximately equal distances allow for a more even flow of liquid refrigerant between the outlet end 248 of the inlet pipe assembly 240 and the side wall 234 of the accumulator housing 222.

[0027] As illustrated in FIG. 3, it is desirable for the distance from the inlet end 270 of the outlet fluid pipe assembly 260 to the top wall 228 of the accumulator housing to be greater than the distance from the outlet end 248 of the inlet fluid pipe assembly 240 to the top wall 228 of the accumulator housing. This arrangement further reduces the possibility of inlet refrigerant from unintentionally entering the inlet end 270 of the outlet fluid pipe assembly 260.

[0028] FIG. 5 illustrates a second embodiment of a fluid inlet pipe assembly according to the present invention. The fluid inlet pipe assembly 340 is similar to the fluid inlet pipe assembly 240 of the first embodiment except the cut forming the outlet end 348 of the fluid inlet pipe assembly 340 is made in a curved diverter/diffuser portion 346 of the fluid inlet pipe assembly 340. In other words, the cut forming the outlet end 348 is made between the tubular vertical portion 342 and the center point C1 defining the curvature of the curved diverter/diffuser portion 346. By forming the outlet end 348 at the curved diverter/diffuser portion 346 of the inlet pipe assembly 340; similar to the first embodiment, the flow of the refrigerant mixture out of the outlet end 348 is directed towards the side wall 334 so that entrained liquid will flow dowardly along the side wall 334, and directed downwardly away from the inlet end 370 the outlet pipe assembly 360.

[0029] Furthermore, with the cut for forming the outlet end 348 made at a curved tubular section defining the diverter/diffuser portion 346, similar to the first embodiment, the outlet end 348 of the fluid inlet pipe assembly 340 has a cross-sectional area greater than the average cross-sectional area perpendicular to the axis of the vertical portion 342. With the outlet end 348 having a greater cross-sectional area, the outlet end 348 is able to act as a diffuser diffusing the flow of refrigerant coming out the outlet end 348; thus, reducing or preventing turbulent flow of refrigerant.

[0030] FIGS. 6 and 7 illustrate a third embodiment of a fluid inlet pipe assembly 440 according to the present invention. The fluid inlet pipe assembly 440 includes a tubular vertical portion 442 and a diverter/deflecting portion 446. The fluid inlet pipe assembly 440 is formed by first providing a straight pipe. A notch is cut near one end of the pipe leaving a long end at one longitudinal direction from the notch and a short end at other longitudinal direction for the notch. The long end of the pipe defines the vertical portion 442 of the fluid inlet pipe assembly 440. The notch can be made such that the notch completely cuts through one longitudinal surface of the short end. Alterative if the notch does not completely cut through one longitudinal surface of the short end, another cut is made longitudinally along the short end of the notched pipe.

[0031] The short end of the pipe is unfolded to form and an unfolded section. Depending on how the short end is unfolded, the unfolded section can be cylindrical, conical or virtually flat. The unfolded section is then bent along the notch to an angle less than 90 degrees to define the diverter/diffuser portion 446. The angle the axis of the vertical portion 442 from the axis of the diverter/diffuser portion 446 is preferably between 10 degrees to 80 degrees, and more preferably between 15 degrees to 45 degrees. Similar to the first and second embodiments, the flow of the refrigerant mixture flowing from the diverter/diffuser portion 446 is directed towards the side wall 434 so that entrained liquid will flow dowardly along the side wall 434, and directed downwardly away from the inlet end 470 of the outlet pipe assembly 460. Furthermore, due the diverter/diffuser portion 446 formed by unfolding a section of pipe, the average radius of the inner surface of the diverter/diffuser portion 446 is greater than the average radius of the vertical portion 442. This greater radius of the inner surface of the diverter/diffuser portion 446 allows the inner surface of the diverter/diffuser portion to act as a diffuser diffusing the flow of refrigerant coming out the outlet end 448; thus, reducing or preventing turbulent flow of refrigerant.

[0032] FIGS. 8 and 9 illustrate a fourth embodiment of a fluid inlet pipe assembly 540 according to the present invention. The fluid inlet pipe assembly 540 has a straight vertical portion 542 attached to the top wall 528 of the accumulator housing 522. The vertical portion 542 has a fluid flow opening 543 directed downwardly towards the bottom wall 532 of the accumulator housing 522. Attached to the end of the vertical portion 542 is a separate diverter/diffuser assembly 545 having a diverter/diffuser portion 546 for diverting the flow of the refrigerant mixture from the fluid flow opening 543 towards the sidewall 534 so the entrained liquid will flow dowardly along the sidewall 534, and directed downwardly away from the entrance to the outlet pipe.

[0033] The diverter/diffuser assembly 545 includes a mounting ring 550, a plurality of posts 552 connecting the mounting ring 550 to the diverter/diffuser portion 546. The mounting ring 550 is adapted to be mounted onto and attached to the outer surface of the vertical portion 542. The mounting ring 550 has an inner diameter slight larger than the outer diameter of the outer surface of the vertical portion 542. The inner diameter of the mounting ring 550 should be sized to allow for a tight fit between the mounting ring 550 and the vertical portion 542, but still be able to slide over the outer surface of the vertical portion 542 during the mounting process without breaking the mounting ring 550. The mounting ring 550 can be attached to the vertical portion 542 by glue, welding, brazing, mechanical or other attachment means. Three posts 552 connect the mounting ring 550 to the diverter/diffuser portion 546. While the illustrated embodiment has three posts 552, any number of posts capable of connecting the ring portion to the deflection portion should be considered to be within the scope of this invention. The spacings between the posts 552 define flow passages 554 for the refrigerant to flow through. The diverter/diffuser portion 546 has a conical outer surface. Alternatively the deflecting portion can have a frusto-conical outer surface. The conical outer surface deflects the refrigerant flowing out of the fluid flow opening 543 towards the sidewall. Due to the conical or frusto-conical surface having a radially expanding surface, the diverter/diffuser portion 546 not only re-directs the refrigerant, but as the refrigerant flows dowardly along the radially expanding surface, the refrigerant is spread out to diffuse the refrigerant. The deflector may be made from molded plastic, cast zinc, stamped aluminum or other materials.

[0034] FIG. 10 illustrates a fifth embodiment of a fluid inlet pipe assembly 640 according to the present invention. The fluid inlet pipe assembly 640 is attached to the top wall 628 of the accumulator housing 622. The fluid inlet pipe assembly includes a tubular vertical portion 642, a tubular diverter portion 646 and a curved portion 644 connecting the vertical portion 642 to the diverter portion 646. The vertical portion 642 has an axis approximately parallel with the axis of the accumulator housing 622. To allow the inlet end 670 of the outlet pipe assembly 660 to be located near the ceiling of the accumulator housing 622, the axis of the vertical portion 642 is offset from the inlet end 670 of the outlet pipe assembly 660. In other words, the axis of the vertical portion 642 does not intersect the inlet end 670 of the outlet pipe assembly 660. Such an arrangement allows the inlet end 670 of the outlet pipe assembly 660 to be located adjacent to the vertical portion 642 of the inlet pipe 640, rather than, below the vertical portion 642 of the inlet pipe 640.

[0035] The axis of the diverter portion 646 is at an angle approximately 90 degrees from the axis of the vertical portion 642. By bending the pipe for forming the inlet pipe assembly 640 at an angle approximately 90 degrees, the flow of the inlet refrigerant mixture is directed towards the side wall 634. By directing the inlet refrigerant mixture towards the side wall 634, the liquid refrigerant is able to flow downwardly along the side wall 634 to the bottom sump portion of the accumulator housing 622.

[0036] The terminal end of the diverter portion 646 defines the outlet end 648 of the fluid inlet pipe assembly 640. The outlet end 648 of the fluid inlet pipe assembly 640 is formed by making an angular cut across the diverter portion 646 such that the plane of the cut is approximately parallel to the axis of the vertical portion 642 and the cut is made beyond the center point C2 defining the curvature of the curved portion 644.

[0037] In addition, it is desirable for the distance from the inlet end 670 of the outlet fluid pipe assembly 660 to the top wall 628 of the accumulator housing to be greater than the distance from the outlet end 648 of the inlet fluid pipe assembly 640 to the top wall 628 of the accumulator housing. This arrangement reduces the possibility of inlet refrigerant from unintentionally entering the inlet end 670 of the outlet fluid pipe assembly 660.

[0038] FIG. 11 illustrates a sixth embodiment of a fluid inlet pipe assembly 740 according to the present invention. The fluid inlet pipe assembly 740 is attached to the top wall 728 of the accumulator housing 722. The fluid inlet pipe assembly includes a tubular vertical portion 742 and a tubular diverter/diffuser portion 746. The tubular diverter/diffuser portion includes a tubular horizontal sub-portion 746b and a curved sub-portion 746a connecting the vertical portion 742 to the horizontal sub-portion 746b. The vertical portion 742 has an axis approximately parallel with the axis of the accumulator housing 722. To allow the inlet end 770 of the outlet pipe assembly 760 to be located near the ceiling of the accumulator housing 722, the axis of the vertical portion 742 is offset from the inlet end 770 of the outlet pipe assembly 760. In other words, the axis of the vertical portion 742 does not intersect the inlet end 770 of the outlet pipe assembly 760. Such an arrangement allows the inlet end 770 of the outlet pipe assembly 760 to be located adjacent to the vertical portion 742 of the inlet pipe 740, rather than, below the vertical portion 742 of the inlet pipe 740.

[0039] The axis of the horizontal sub-portion 746b is at an angle approximately 90 degrees from the axis of vertical portion 742. The terminal end of the fluid inlet pipe assembly 740 defines an outlet end 748. The outlet end 748 of the fluid inlet pipe assembly 740 is formed by making an angular cut across the diverter/diffuser portion 746 such that the bottom edge 747a of the diverter/diffuser portion 746 extends further from the axis of the vertical portion 742 than the top edge 747b of the diverter/diffuser portion 746. It is preferable that the bottom edge 746a extends beyond the center point C3 defining the curvature of the curved sub-portion 746a and the top edge 746b be located between the tubular vertical portion 742 and the center point C3. The angle β from the plane of the cut forming the outlet end 748 to a plane perpendicular to the axis of the horizontal sub-portion 746b is preferably between 30 degrees to 60 degrees, and more preferably at approximately 45 degrees. By forming the outlet end 748 with the bottom edge 747a of the diverter/diffuser portion 746 extending further from the axis of the vertical portion 742 of the diverter/diffuser portion 746, the outlet end 748 is directed towards the side wall 734 and upwardly towards the ceiling 730 of the accumulator housing 722. By directing the inlet refrigerant mixture towards the side wall 734, the liquid refrigerant is able to flow downwardly along the side wall 734 to the bottom sump portion of the accumulator housing.

[0040] Furthermore, since the plane of the cut forming the outlet end 748 is at angle from the plane perpendicular to the axis of the horizontal sub-portion 746b, the outlet end 748 of the fluid inlet pipe assembly 740 has a cross-sectional area greater than the average cross-sectional area perpendicular to the axis of the vertical portion 742. With the outlet end 748 having a greater cross-sectional area, the outlet end 748 is able to act as a diffuser diffusing the flow of refrigerant coming out the outlet end 748; thus, reducing or preventing turbulent flow of refrigerant.

[0041] In addition, it is desirable for the distance from the inlet end 770 of the outlet fluid pipe assembly 760 to the top wall 728 of the accumulator housing to be greater than the distance from the outlet end 748 of the inlet fluid pipe assembly 740 to the top wall 728 of the accumulator housing. This arrangement reduces the possibility of inlet refrigerant from unintentionally entering the inlet end 770 of the outlet fluid pipe assembly 760.

[0042] While the above embodiments of the present invention are illustrated with the trumpet shaped outlet tube, the use of the trumpet shaped outlet tube is not necessary to recognize the improved performance of an accumulator using an inlet tube assembly in accordance to the present invention. Improved performance of an accumulator using an inlet tube assembly in accordance to the present invention can also be recognized with a baffle attached to the accumulator housing or to the outlet tube. Furthermore, while the improved performance of the accumulator using an inlet tube assembly in accordance to the present invention is more evident with the inlet tube assembly attached to the top wall, an improved performance of the accumulator using an inlet tube assembly in accordance will also be recognized with the inlet tube assembly attached to the side wall.

[0043] In addition to improving the performance of the accumulator by using an inlet tube assembly in accordance to the present invention to divert the refrigerant toward the side wall and downwardly while diffusing the refrigerant to reduce turbulent, turbulent flow of the refrigerant can also be reduced by an improved flow path defined in the inlet fitting with fewer sharp edges. As stated in the background section, turbulent flow may also be caused by the refrigerant flowing through the flow passage defined within an inlet fitting. FIGS. 12 and 13 illustrate a typical inlet fitting 36 with a bent flow path. The inlet fitting 36 defines a first straight fluid passage 60 and a second straight fluid passage 64, wherein the first straight fluid passage 60 intersects the second straight fluid passage 64 at an intersection point 68. The first straight fluid passage 60 has a cylindrical bore 70 and a conical terminal end 62. The second straight fluid passage 64 has a cylindrical bore 72 and a conical terminal end 66. The cylindrical bore 70 of the first straight fluid passage 60 has a diameter D1 greater than the diameter D2 of the cylindrical bore 72 of the second straight fluid passage 64. To assure that the intersection of the first fluid passage 60 with the second fluid passage 64 does not restrict the flow of refrigerant flowing through the bent flow path, the cylindrical bore of the first fluid passage and the cylindrical bore of the second fluid passage extend at least to the intersection point 68. However, due to the conical terminal end 62 of the first fluid passage 60 and/or the conical terminal end 66 of the second fluid passage 64, a protrusion 74 may be defined near the intersection point 68. The protrusion 74 and the transition from the cylindrical bores 70, 72 to the corresponding conical ends 62, 66 create sharp edges that may cause turbulence and pressure drop in the refrigerant flowing through the bent path of the inlet fitting 36.

[0044] FIGS. 14 and 15 illustrate an inlet fitting with a bent flow path according to the second aspect of the present invention. The inlet fitting 836 in according to the present invention defines a first straight fluid passage 860 and a second straight fluid passage 864, wherein the first straight fluid passage 860 intersects the second straight fluid passage 864 at an intersection point 868. The first straight fluid passage 860 has a cylindrical bore 870 and a concave terminal end 862. The second straight fluid passage 864 has a cylindrical bore 872 and a concave terminal end 866. To assure that the intersection of the first fluid passage 860 with the second fluid passage 864 does not restrict the flow of refrigerant flowing through the bent flow path, the cylindrical bore of the first fluid passage and the cylindrical bore of the second fluid passage extend at least to the intersection point 868. Since the terminal ends of the fluid passages 860, 864 are defined by concave or rounded surfaces 862, 866, sharp notches and sharp transition edges from the cylindrical bores to the end surfaces are essentially eliminated in the bent flow path in the inlet fitting 836 in accordance to the present invention. A flow path having a full-radius shaped intersection improves the flow and reduces turbulence and pressure drop. One method to create such concave terminal ends is to use ball end cutters with full-radius shape drill points, instead of the industry typical cutter with sharp conical drill points. It is preferable that the inlet fitting 836 have the diameter D4 of the cylindrical bore 872 of the second fluid passage 864, in the order of fluid path, be equal or greater than the diameter D3 of the cylindrical bore 870 of the first fluid passage 860 to prevent any restrictions in the fluid flow path. It is also preferable that the inner diameter of the section of the inlet pipe assembly inserted into the second fluid passage be equal or greater than the diameter D3 of the cylindrical bore 870 of the first fluid passage 860 to prevent any restrictions in the fluid flow path.

[0045] It should be noted that while the use of a diverter/diffuser portion in accordance to the first aspect of the present invention can be used in conjunction with an inlet fitting in accordance to the second aspect of the present invention to increase the overall performance of the accumulator, the diverter/diffuser portion in accordance to the first aspect of the present invention and the inlet fitting in accordance to the second aspect of the invention can be used independently and still be able recognize an increase in performance of the accumulator.

[0046] Various features of the present invention have been described with reference to the above embodiments. It should be understood that modification may be made without departing from the spirit and scope of the invention as represented by the following claims.

Claims

1. An accumulator for use in a motor vehicle air conditioning system, said accumulator comprising: an accumulator housing having a top wall, a bottom wall, and a side wall connecting the top wall to the bottom wall; an outlet fluid pipe assembly having an inlet end; and an inlet fluid pipe assembly includes a tubular first portion and a diverter/diffusing portion configured to direct refrigerant flowing through said first portion towards the sidewall and downwardly away from the top wall of the accumulator housing, said first tubular portion having an axis offset from said inlet end of said outlet fluid pipe assembly.

2. The accumulator as claimed in claim 1 wherein said inlet fluid pipe has an outlet opening, the distance from said inlet end of the outlet fluid pipe assembly to the top wall of the accumulator housing is greater than the distance from the outlet end of the inlet fluid pipe assembly to the top wall of the accumulator housing.

3. The accumulator as claimed in claim 1 wherein said inlet fluid pipe assembly is mounted to the top wall of the accumulator housing.

4. The accumulator as claimed in claim 1 wherein said outlet fluid pipe assembly is mounted to the sidewall of the accumulator housing.

5. The accumulator as claimed in claim 1 wherein said outlet fluid pipe assembly is U-shaped.

6. The accumulator as claimed in claim 1 wherein a single pipe forms both the first portion and said diverter/deflector portion.

7. The accumulator as claimed in claim 1 wherein said first portion of said inlet pipe assembly has an axis approximately parallel to the axis of the accumulator housing.

8. The accumulator as claimed in claim 7 wherein said diverter/diffuser portion of said inlet pipe assembly has an axis greater than 0 degree and less than 90 degrees from the axis of the first portion.

9. The accumulator as claimed in claim 8 wherein said diverter/diffuser portion has an axis between 10 to 80 degrees from the axis of the first portion.

10. The accumulator as claimed in claim 9 wherein said diverter/diffuser portion has an axis between 15 to 45 degrees from the axis of the first portion.

11. The accumulator as claimed in claim 1 wherein said diverter/diffuser portion has an outlet opening, the cross-sectional area of the outlet opening is greater than the average cross-sectional area perpendicular to the axis of the first portion.

12. The accumulator as claimed in claim 11 wherein the average cross-sectional area perpendicular to the axis of the diverter/diffuser portion is approximately equal to the average cross-sectional area of the axis of the axis of the first portion.

13. The accumulator as claimed in claim 1 wherein the plane of said outlet opening is approximately parallel to the axis of the accumulator housing.

14. The accumulator as claimed in claim 1 wherein the plane of said outlet opening is approximately parallel to the axis of the first portion.

15. The accumulator as claimed in claim 6 wherein said diverter/diffuser portion is formed by unfolding a section of said single pipe.

16. The accumulator as claimed in claim 1 wherein said diverter/diffuser portion is a separate component attached to the first portion.

17. The accumulator as claimed in claim 16 wherein said diverter/diffuser portion is conical or frusto-conical shaped.

18. The accumulator as claimed in claim 16 wherein said inlet pipe assembly further includes a mounting ring and a plurality of posts connecting said ring to said diverter/diffuser portion.

19. An accumulator assembly for use in a motor vehicle air conditioning system, said accumulator assembly comprising: an accumulator housing having a top wall, a bottom wall, and a side wall connecting the top wall to the bottom wall; an outlet fluid pipe assembly; an inlet fluid pipe assembly; and an inlet fitting attached to said top wall of said accumulator housing, a first straight fluid passage having a concave terminal end defined in said inlet fitting, a second straight fluid passage having a concave terminal end defined in said inlet fitting, said inlet fluid pipe assembly has a tubular portion insertable into an opening of said second straight fluid passage, said first straight fluid passage intersects said second fluid passage to allow refrigerant to flow from said first straight fluid passage to said second straight fluid passage and into said inlet fluid pipe assembly.

20. An accumulator assembly as claimed in claim 19 wherein the diameter of said first straight passage is approximately equal to the inner diameter of said tubular portion of said inlet fluid pipe assembly.

21. An accumulator assembly as claimed in claim 19 wherein the diameter of said first straight passage is less than the inner diameter of said tubular portion of said inlet fluid pipe assembly.

22. An accumulator for use in a motor vehicle air conditioning system, said accumulator comprising: an accumulator housing having a top wall, a bottom wall, and a side wall connecting the top wall to the bottom wall; an outlet fluid pipe assembly having an inlet end; and an inlet fluid pipe assembly includes a tubular first portion and a diverter/diffusing portion configured to direct refrigerant flowing through said first portion towards the sidewall and upwardly towards the top wall of the accumulator housing, said first tubular portion having an axis offset from said inlet end of said outlet fluid pipe assembly.

23. The accumulator as claimed in claim 22 wherein said diverter/diffuser portion has an outlet opening, the cross-sectional area of the outlet opening is greater than the average cross-sectional area perpendicular to the axis of the first portion.

24. The accumulator as claimed in claim 23 wherein the bottom edge of the diverter/diffuser portion extends further from the axis of the vertical portion than the top edge of the diverter/diffuser portion from the axis of the vertical portion.

25. The accumulator as claimed in claim 23 wherein the diverter/diffuser portion includes a sub-portion, the outlet end defines a plane between 30 degrees to 60 degrees from a plane perpendicular to the axis of the sub-portion.