1. Field of the Invention
The present invention relates to a heat exchanger, and more particularly, to a heat exchanger, in which inlet and outlet side heat exchange parts are fluidically communicated with each other and have the same refrigerant flowing direction by fluidically intercommunicating pairs of cups which are located at a predetermined area of the center of the heat exchanger, thereby being easily reduced in size, providing uniform surface temperature distribution of the heat exchanger and improving heat exchange efficiency by reducing the preponderance and the pressure drop rate of refrigerant and inlet and outlet pipes being easily arranged forward.
2. Background Art
In general, a heat exchanger includes a flow channel for allowing a flow of heat exchange medium therein, so that the heat exchange medium exchanges heat with the external air. The heat exchanger is used in various air conditioning devices, and is employed in various forms such as an evaporator, a condenser, a radiator and a heater core according to various using conditions.
The evaporator of the various heat exchangers is divided according to structural types of refrigerant passageways. Representatively, there are a serpentine type multilayerly bending one collapsible tube and a laminate type formed by piling up dimple type plates. In addition, recently, an evaporator using plural collapsible tubes has been introduced.
As an example of such conventional evaporator, Japanese Utility Model Publication No. 7-12778 discloses an evaporator. Referring to FIG. 1, the evaporator 1 includes a plurality of tubes each of which is formed by bonding two plates 11 having pairs of cups 12 at the upper and lower end thereof. The plural tubes are laminated in multi layers.
The evaporator which is formed by laminating the plural tubes includes tanks 2 and 3 formed on the upper and lower portions thereof, and inlet and outlet pipes 4 and 5 disposed at a side therefore for flow-in and flow-out of refrigerant.
Therefore, an inlet side heat exchange part 20a is formed at a part fluidically communicated with the inlet pipe 4, and an outlet side heat exchange part 20b is formed at a part fluidically communicated with the outlet pipe 5.
Furthermore, a fluid communication part 25 is mounted at a part of the evaporator opposed to the inlet and outlet pipes 4 and 5 for fluidically communicating the inlet side heat exchange part 20a with the outlet side heat exchange part 20b. 
Meanwhile, partition walls 26 are formed inside the upper tank 2 in a row for dividing the inlet and outlet side heat exchange parts 20a and 20b into a plurality of heat exchange zones 21 to 24, and heat radiation fins 15 are interposed between the tubes 10 for promoting heat exchange.
Referring to FIG. 2, a flow of refrigerant of the evaporator 1 will be described hereinafter.
Refrigerant induced into the upper tank 2 of the inlet side heat exchange part 20a through the inlet pipe 4 flows downwardly at the first heat exchange zone 21 divided by the partition wall 26, and then, moves into the lower tank 3. Refrigerant flowing into the lower tank 3 is returned at the lower tank 3, flows upwardly at the second heat exchange zone 22, and moves into the upper tank 2.
Refrigerant passing through the inlet side heat exchange part 20a is induced into the upper tank 2 of the outlet side heat exchange part 20b through the fluid communication part 25.
Refrigerant induced into the upper tank 2 of the outlet side heat exchange part 20b flows downwardly at the third heat exchange zone 23 divided by the partition wall 26, and moves into the lower tank 3. Refrigerant flowing into the lower tank 3 is returned at the lower tank 3, flows upwardly at the fourth heat exchange zone 24, and moves into the upper tank 2. After that, refrigerant is discharged to the outside through the outlet pipe 5.
In the meantime, the first heat exchange zone 21 is a zone where refrigerant of the upper tank 2 flows downwardly along the tube 10 and moves into the lower tank 3. At this time, since gravity is applied to refrigerant flowing inside the upper tank 2, the volume of refrigerant induced into each tube 10 is gradually increased at the first half stage of refrigerant inducement, but is gradually decreased at the second half stage.
The second heat exchange zone 22 is a zone where refrigerant induced into the lower tank 3 from the first heat exchange zone 21 flows upwardly along the tube 10 and is induced into the upper tank 2. Since inertia is applied to refrigerant flowing inside the lower tank 3, the volume of refrigerant induced into each tube 10 is gradually decreased at the first half stage of the refrigerant inducement, but is gradually increased at the second half stage.
The third heat exchange zone 23 is a zone where refrigerant induced into the upper tank 2 through the fluid communication part 25 from the second heat exchange zone 22 flows downwardly along the tube 10 and moves into the lower tank 3. At this time, since gravity is applied to refrigerant flowing inside the upper tank 2, the volume of refrigerant induced into each tube 10 is gradually increased at the first half stage of the refrigerant inducement, but is gradually decreased at the second half stage.
The fourth heat exchange zone 24 is a zone where refrigerant induced into the lower tank 3 from the third heat exchange zone 23 flows upwardly along the tube 10 and is induced into the upper tank 2. Since inertia is applied to refrigerant flowing inside the lower tank 3, the volume of refrigerant induced into each tube 10 is gradually decreased at the first half stage of the refrigerant inducement, but is gradually increased at the second half stage.
Therefore, there occurs a severe surface temperature difference of the evaporator 1 due to lopsidedness of refrigerant, and it occurs more severely when the flow amount of refrigerant is small or the air passing through the evaporator 1 is in a low airflow. That is, inside the inlet and outlet side heat exchange parts 20a and 20b, an overcooled section is formed in the tube 10 in which refrigerant of large quantity flows and an overheated section is formed in the tube in which refrigerant of small quantity flows.
Moreover, in the above flow channel structure, the overcooled section and the overheated section are formed at nearly similar locations of the inlet side heat exchange part 20a and the outlet side heat exchange part 20b. Most of the air passing through the overcooled section of the outlet side heat exchange part 20b passes through the overcooled section of the inlet side heat exchange part 20a, and most of the air passing through the overheated section of the outlet side heat exchange part 20b passes through the overheated section of the inlet side heat exchange part 20a. Therefore, the air passing between all of the tubes 10 does not exchange heat uniformly, and so, the temperature distribution difference of the discharged air becomes more severe. In addition, a problem of icing may occur on the surface of the evaporator and the air-conditioner system becomes unstable in the overcooled section. Additionally, in the overheated section, since the discharged air is not normally cooled and dehumidified, temperature-increased damp air is induced into a car, and thereby, passengers may feel uneasiness.
A pressure drop rate of refrigerant is increased by the fluid communication part 25 separately mounted at an end of the tank 2 for fluidically communicating the inlet side heat exchange part 20a with the outlet side heat exchange part 20b, and so, it causes deterioration of heat exchange performance, and obstructs miniaturization of the heat evaporator.
Furthermore, the conventional evaporator has another problem in that it is difficult to arrange the inlet pipe 4 and the outlet pipe forward since they are all arranged at one side of the evaporator 1.