Condenser Having Partitions for Changing the Refrigerant Flow Direction

1. Technical Field

The present invention relates to a heat exchanger, and more particularly, to a heat exchanging condenser for use in an automative air-conditioning system.

2. Description of the Prior Art

With reference to FIG. 1, a conventional refrigerant circuit for use, for example, in an automotive air-conditioning system is shown. Circuit 1 includes compressor 10, condenser 20, receiver or accumulator 30, expansion device 40, and evaporator 50 serially connected through pipe members 60 which link the outlet of one component with the inlet of a successive component. The outlet of evaporator 50 is linked to the inlet of compressor 10 through pipe member 60 so as to complete the circuit. The links of pipe members 60 to each component of circuit 1 are made such that the circuit is hermetically sealed.

In operation of circuit 1, refrigerant gas is drawn from the outlet of evaporator 50 and flows through the inlet of compressor 10, and is compressed and discharged to condenser 20. The compressed refrigerant gas in condenser 20 radiates heat to an external fluid flowing through condenser 20, for example, atmospheric air, and condenses to the liquid state. The liquid refrigerant flows to receiver 30 and is accumulated therein. The refrigerant in receiver 30 flows to expansion device 40, for example, a thermostatic expansion valve, where the pressure of the liquid refrigerant is reduced. The reduced pressure liquid refrigerant flows through evaporator 50, and is vaporized by absorbing heat from a fluid flowing through the evaporator, for example, atmospheric air. The gaseous refrigerant then flows from evaporator 50 back to the inlet of compressor 10 for further compression and recirculation through circuit 1.

With further reference to FIGS. 1a, and 2-5, a prior art embodiment of condenser 20 as disclosed in Japanese Patent Application Publication No. 63-112065 is shown. Condenser 20 includes a plurality of adjacent, essentially flat tubes 21 having an oval cross-section and open ends which allow refrigerant fluid to flow therethrough. A plurality of corrugated fin units 22 are disposed between adjacent tubes 21. Circular header pipes 23 and 24 are disposed perpendicularly to flat tubes 21 and may have, for example, a clad construction. Each header pipe 23 and 24 includes outer tube 26 which may be made from aluminum and inner tube 28 made of a metal material which is brazed to the inner surface of outer tube 26. Outer tube 26 has slits 27 disposed therethrough. Flat tubes 21 are fixedly connected to header pipes 23 and 24 and are disposed in slits 27 such that the open ends of flat tubes 21 communicate with the hollow interior of header pipes 23 and 24. Inner tube 28 includes portions 28a which define openings corresponding to slits 27. Portions 28a are brazed to the inner ends of flat tubes 21 and ensure that tubes 21 are hermetically sealed within header pipes 23 and 24 when inserted in slits 27.

Header pipe 23 has an open top end and a closed bottom end. The open top end is sealed by inlet union joint 23a which is fixedly and hermetically connected thereto. Inlet union joint 23a is linked to the outlet of compressor 10. Partition wall 23b is fixedly disposed within first header pipe 23 at a location about midway along its length and divides header pipe 23 into upper cavity 231 and lower cavity 232 which is isolated from upper cavity 231. Second header pipe 24 has a closed top end and an open bottom end. The open bottom end is sealed by outlet union joint 24a fixedly and hermetically connected thereto. Outlet union joint 24a is linked to the inlet of receiver 30. Partition wall 24b is fixedly disposed within second header pipe 24 at a location approximately one-third of the way along the length of second header pipe 24 and divides second header pipe 24 into upper cavity 241 and lower cavity 242 which is isolated from upper cavity 241. The location of partition wall 24b is lower than the location of partition wall 23a.

In operation, compressed refrigerant gas from compressor 10 flows into upper cavity 231 of first header pipe 23 through inlet union joint 23a, and is distributed such that a portion of the gas flows through each of flat tubes 21 which are disposed above the location of partition wall 23b, and into an upper portion of upper cavity 241. Thereafter, the refrigerant in the upper portion of cavity 241 flows downward into a lower portion of upper cavity 241, and is distributed such that a portion flows through each of the plurality of flat tubes 21 disposed below the location of partition wall 23b and above the location of partition wall 24b, and into an upper portion of lower cavity 232 of first header pipe 23. The refrigerant in an upper portion of lower cavity 232 flows downwardly into a lower portion, and is again distributed such that a portion flows through each of the plurality of flat tubes 21 disposed below the location of partition wall 24b, and into lower cavity 242 of second header pipe 24. As the refrigerant gas sequentially flows through flat tubes 21, heat from the refrigerant gas is exchanged with the atmospheric air flowing through corrugated fin units 22 in the direction of arrow W as shown in FIG. 5. Since the refrigerant gas radiates heat to the outside air, it condenses to the liquid state as it travels through tubes 21. The condensed liquid refrigerant in cavity 242 flows out therefrom through outlet union joint 24a and into receiver 30 and the further elements of the circuit as discussed above.

With reference to FIG. 6 a portion of a similar prior art condenser which is disclosed in U.S. Pat. No. 4,825,941 is shown. Header pipe 13 includes slit 29 formed on an opposite side thereof from slits 27 and at a vertical location between two adjacent slits 27. Although not shown in the Figure, header pipe 13 could include a brazing layer 28 as shown in FIG. 4. Partition plate 70 includes smaller diameter semi-circular portion 70a and larger diameter semi-circular portion 70b integrally formed such that the two semi-circular portions are joined at their chordal surfaces. Portion 70a has a radius substantially equal to the inner radius of header pipe 13 and portion 70b has a radius substantially equal to the outer radius of header pipe 13. Partition plate 70 is disposed and soldered in slit 29 such that portion 70a fits flush against the inner surface of pipe 13 and the outer surface of portion 70b is disposed so as to be substantially even with the outer surface of header pipe 13. Both plate 70 and header pipe 13 are provided with layers of solder so as to ensure that no leakage of refrigerant fluid occurs between the interior portions of pipe 13 which are separated by plate 70, or from the interior of pipe 13 to the outside.

In the condenser shown in FIG. 6, header pipe 13 must be formed with a plurality of slits 29 and a corresponding plurality of partitions 70 having circular portions 70a and 70b, as described above. The process for constructing headers of this type is complicated and results in a great deal of wasted time and material if the parts do not fit or seal properly. Additionally, condensers are disposed at the high pressure side of a refrigeration circuit, and also may be mounted within the engine compartment in a position where they will be subjected to numerous highly concussive vibrations. As a consequence of the vibrations and the high pressure of the refrigerant in the condenser, undesirable leakage of the refrigerant through slits 29 to the atmosphere may occur. Therefore, lit is not desirable to increase the number of slits in header pipe 13 by the addition of slits 29 since this increase results in a corresponding increase in the possibility of refrigerant leaking to the outside of pipe 13.

The present invention is directed to a condenser for a refrigerant fluid circuit. The condenser includes a plurality of tubes having opposite first and second open ends, and a plurality of fin units disposed between the plurality of tubes. First and second header pipes are fixedly disposed at the opposite ends respectively, and the open ends of the tubes are disposed in fluid communication with the interior of the header pipes. The first header pipe has an inlet which links the condenser to an external element of the circuit. The first header pipe also has an outlet which links the condenser to an external element of the circuit. Partitions are provided in at least one of the header pipes to create isolated chambers therein. The partition comprises a horizontal portion with a peripheral portion extending perpendicularly to the horizontal portion. The partition is inserted into the header pipe through an open end.

In a further embodiment, the outer diameter of the partition is substantially equal to the inner diameter of the header pipes.

In a further embodiment the peripheral portion comprises a hollow cylinder and the horizontal portion comprises a disc.

In a further embodiment the peripheral portion comprises a a hollow conical slice and the horizontal portion comprises a solid conical slice.

In a further embodiment the a peripheral portion extends from both sides of the horizontal portion.

The present invention provides the first advantage that the condenser is constructed to withstand concussive vibrations and the high pressure of the refrigerant flowing therethrough so as to reliably prevent leakage of the refrigerant to the outside. The invention provides the additional advantage that the construction of the condenser is simplified and the need for slits through which the partitions are disposed is eliminated.

Further objects, features and aspects of this invention will be understood from the following detailed description of the preferred embodiments of this invention with references to the drawings.

FIG. 1 is a schematic block diagram of a refrigerant circuit in accordance with the prior art.

FIG. 1a is an elevational view of the condenser shown in the refrigerant circuit of FIG. 1.

FIG. 2 is a perspective view of certain elements of the condenser shown in FIG. 1a.

FIG. 3 is a top view of the condenser shown in the prior art of FIG. 1a.

FIG. 4 is a partial cross-section along line 4--4 in FIG. 1a.

FIG. 5 is a partial cross-section along line 5--5 in FIG. 1a.

FIG. 6 is a perspective view showing a partition according to the prior art.

FIG. 7 is a cross-sectional view of a condenser in accordance with a first embodiment of the present invention.

FIG. 8(a) is a cross-sectional view of a partition in accordance with a first embodiment of the present invention.

FIG. 8(b) is a perspective view of a partition as shown in FIG. 8(a).

FIG. 9(a) is a cross-sectional view of a partition in accordance with a second embodiment of the present invention.

FIG. 9(b) is a perspective view of a partition as shown in FIG. 9(a).

FIG. 10(a) is a cross-sectional view of a partition in accordance with a third embodiment of the present invention.

FIG. 10(b) is a perspective view of a partition as shown in FIG. 10(a).

With reference to FIG. 7, a condenser in accordance with a first embodiment of the present invention is shown. In the Figures, the same reference numerals are used to denote corresponding elements shown in the prior art figures. Therefore, a complete explanation of those elements is omitted. Condenser 200 includes a plurality of flat or planar tubes 21, and a plurality of corrugated fin units 22 alternately arranged and forming heat exchange region 200a. Flat tubes 21 are preferably made of aluminum and have a multi-hollow construction, that is, flat tubes 21 include a plurality of longitudinally disposed dividing walls such that each flat tube includes a plurality of parallel flow paths. This construction increases the surface area the refrigerant fluid contacts as it flows through the flat tubes. Flat tubes 21 are disposed in slots 27 in header pipes 130 and 140 disposed at the opposite ends of the flat tubes as discussed with respect to FIG. 4.

Open-ended header pipes 130 and 140 are cylindrical and are preferably made of aluminum. Although not shown in FIG. 7, header pipes 130 and 140 could include a brazing portion as discussed with respect to FIG. 4. Partitions 71 and 72 are disposed at an upper and a lower location within header pipe 130 and upper plug 15 is disposed in the top open end and lower plug 16 is disposed in the lower open end. The partitions and plugs divide header pipe 130 into upper fluid chamber 130a, intermediate fluid chamber 130b and lower fluid chamber 130c. The three chambers are isolated from each other. Pipe 240 is disposed through header pipe 130 and links upper chamber 130a with further elements of the refrigerant circuit. Pipe 230 is also disposed through header pipe 130 and links lower chamber 130c with further elements of the refrigerant circuit. Header pipe 140 includes partition 75 disposed therein at a location which is higher than partition 72 and lower than partition 71, and upper plug 17 and lower plug 18 disposed in the top and bottom open ends. Partition 75 and plugs 17 and 18 divide header pipe 140 into upper fluid chamber 140a and lower fluid chamber 140b which are isolated from each other.

With further reference to FIG. 7, tubes 21 are divided into four groups due to the provision of partitions 71, 72 and 75. Lower group A is disposed below the location of partition 72, lower middle group B is disposed above the location of partition 72 and below the location of partition 75, upper middle group C is disposed above the location of partition 75 and below the location of partition 71 and upper group D is disposed above the location of partition 71. Additionally, the number of tubes in each group may be decreased proceeding from the lower groups to the upper groups. That is, group A may have more tubes than group B, group B may have more tubes than group C, and group C may have more tubes than group D. For example, as shown, group A may have five tubes, group B may have four tubes, group C may have three tubes and group D may have two tubes. Thus the total effective cross sectional area for heat exchange of each group decreases accordingly from group A through group D.

In operation of the condenser, the compressed refrigerant gas enters through inlet pipe 230 and proceeds through the condenser in the direction of the arrows. The gaseous refrigerant in lower chamber 130c is distributed such that a portion flows through each of tubes 21 in group A and into a lower part of lower chamber 140b. The refrigerant in the lower part of lower chamber 140b flows to an upper part thereof and is distributed such that a portion flows through each of tubes 21 in group B, and into a lower part of intermediate chamber 130b. Of course, the flow direction in group B is opposite to the flow direction in group A. In a similar manner, the refrigerant is again distributed and flows through the tubes in group C into a lower part of upper chamber 140a, and through the tubes in group D and into upper chamber 130a. As the refrigerant flows through flat tubes 21, it exchanges heat with the air passing through fin units 22 and condenses to the liquid state.

When the refrigerant first enters the tubes in group A, it is entirely in the gaseous state. However, when the refrigerant enters the tubes in group B, a large portion has already condensed to the liquid state. Thus, as is shown in the Figures, it is advantageous to have the effective cross sectional area for heat exchange of group B be less than group A since the volume of a mass of the refrigerant in group B is less than the volume of an equivalent mass in group A since much of the refrigerant has already condensed. Thus less cross-sectional area is needed in group B for efficient heat exchange. Similarly, when the refrigerant enters the tubes in group C, even less of the refrigerant is in the gaseous state, and accordingly, the cross-sectional area of group C is less than the cross-sectional area of group B. By the time the refrigerant reaches group D, it is substantially in the liquid state and the liquid is effectively super-cooled in the tubes in group D. In this manner, the refrigerant smoothly flows through the condenser and efficient heat exchange occurs.

With reference to FIGS. 8(a) and 8(b), the construction of a partition in accordance with a first embodiment of the present invention is shown. Partition 71 has an overall cylindrical shape and includes circular hole 71c extending partially therethrough from one planar surface. Due to hole 71c partition 71 effectively comprises solid cylindrical or disc portion 71a integrally formed with hollow cylindrical portion 71b. As shown in FIG. 8a, a vertical cross section of partition 71 would appear U-shaped with peripheral portions 71b integrally formed with and extending from planar or horizontal portion 71a. The outer diameter of cylindrical partition 71 is selected to be equal to or slightly smaller than the inside diameter of header pipes 130 and 140. In condenser 200 as shown in FIG. 7, partitions 72 and 75, as well as plugs 15, 16, 17 and 18 are of the same construction as partition 71.

With reference to FIGS. 9(a) and 9(b), the construction of a partition in accordance with a second embodiment of the present invention is shown. Partition 80 has an overall frusto-conical shape and includes frusto-conical hole 80c extending partially therethrough from the base. Due to hole 80c, partition 80 effectively comprises solid conical slice portion 80a integrally formed with hollow conical slice portion 80b at the narrow cross-sectional end of portion 80b and the broader cross-sectional end of portion 80a. As shown in FIG. 9b, a vertical cross-section of partition 80 would appear as an outwardly sloping U-shape with peripheral portions 80b integrally formed with and extending from planar or horizontal portion 80a. The outer diameter of the base of frusto-conical partition 80 is selected to be equal to or slightly smaller than the inside diameter of header pipes 130 and 140.

With reference to FIGS. 10(a) and 10(b), the construction of a partition in accordance with a third embodiment of this invention is shown. Partition 91 has an overall cylindrical shape and includes circular holes 91c and 91d extending partially therethrough from both planar surfaces. Due to holes 91c and 91d, partition 91 effectively comprises hollow cylindrical portion 91b integrally formed with circular disc portion 91a disposed therein. Circular disc portion 91a is disposed about the longitudinal axis at a position intermediate of the planar surfaces of partition 91. As shown in FIG. 10a, a vertical cross section of partition 91 would appear H-shaped with vertical portions 91b integrally formed with and extending from planar or horizontal portion 91a. The outer diameter of cylindrical partition 91 is selected to be equal to or slightly smaller than the inside diameter of header pipes 130 and 140. The latter two described embodiments of the partition can be interchanged with partitions and plugs 71, 72 and 75, and 15-18, respectively, as shown in FIG. 7.

The construction of a condenser of the present invention is as follows:

Plug 16 is first inserted into the interior of header pipe 130 through the upper opening thereof, and is then moved by a rod to the lower end of header pipe 130. Partitions 71 and 72 are also inserted in header pipe 130 and moved to their predetermined positions, respectively. Finally, plug 15 is inserted at the upper end of header pipe 130. Since the outer diameter of the plugs and the partitions is predetermined to be approximately the same as or slightly less than the inner diameter of the header pipe, the partitions may be moved smoothly to their respective positions in the header pipe. Additionally, since in all three embodiments the partitions include a horizontal portion and a peripheral portion extending essentially perpendicularly to the horizontal portion and having a central longitudinal axis which is coincident with the longitudinal axis of the header pipes, the partition will not undergo undesirable rotation about an axis perpendicular to the longitudinal axis of the header pipes during insertion. That is, during insertion the partition will remain in an upright orientation and will not flip in the header pipe as it is moved downwardly therein. Pressure is applied through header pipe 130 to each plug and partition by a press to fix their position in header pipe 130 after each has been inserted therein. Partition 75 and plugs 17 and 18 are inserted and fixed within header pipe 140 in a similar manner. After header pipes 130 and 140 are assembled, the remaining parts of the condenser including tubes 21 and pipes 230 and 240 are fixed to the header pipes by brazing. In this case, header pipes 130 and 140 would include a brazing layer as shown in FIG. 4. The condenser may also be assembled by soldering as discussed with respect to FIG. 6. In this case, the soldering layer would be coated on the header pipe and the flat tubes, as well as inlet pipe 230 and outlet pipe 240.

This invention has been described in detail in connection with the preferred embodiments. These embodiments, however, are merely for example only and the invention is not restricted thereto. It will be understood by those skilled in the art that other variations and modifications can easily be made within the scope of this invention, as defined by the appended claims.