Evaporator and process for fabricating same

1. An evaporator comprising:

a refrigerant inlet header;

a refrigerant outlet header arranged side by side with respect to the refrigerant inlet header in a front-rear directionll and a refrigerant circulating passage holding the refrigerant inlet and refrigerant outlet headers in communication with each other therethrough,

wherein the refrigerant inlet header has a refrigerant inlet at one end thereof, the refrigerant outlet header has a refrigerant outlet at one end thereof alongside the refrigerant inlet, the refrigerant inlet permits a refrigerant to flow into the inlet header and to the outlet header through the refrigerant circulating passage so as to be sent out from the refrigerant outlet, the refrigerant inlet header is provided with a cap closing the one end of the refrigerant inlet header and forming the refrigerant inlet, the refrigerant outlet header is provided with a cap closing the one end of the refrigerant outlet header and forming the refrigerant outlet, the caps of the inlet header and the outlet header are joined to a pipe joint member having a refrigerant inlet portion in communication with the refrigerant inlet and a refrigerant outlet portion in communication with the refrigerant outlet, one of the caps and the pipe joint member is provided with a positioning lug which is projecting from a side edge of the one of the caps and the pipe joint member toward other one of the caps and the pipe joint member and which is configured to be fitted with a positioning recess formed in the other one of the caps and the pipe joint member, and the caps and the pipe joint member have flat surfaces to be contact with each other and are brazed such that the positioning lug is engaged with the positioning recess and that the flat surfaces of the caps and the pipe joint member are in contact with each other.

2. The evaporator according to claim 1 , wherein the refrigerant inlet portion and the refrigerant outlet portion of the pipe joint member are each in the form of a tube, a refrigerant inlet pipe having a constricted end portion inserted in and joined to the refrigerant inlet portion, a refrigerant outlet pipe having an end portion inserted in and joined to the refrigerant outlet portion.

3. The evaporator according to claim 2 , wherein the refrigerant inlet portion is smaller than the refrigerant outlet portion in outside diameter.

4. The evaporator according to claim 2 , wherein the refrigerant outlet pipe is provided at said end portion with a constricted portion inserted in and joined to the refrigerant outlet portion.

5. The evaporator according to claim 1 , wherein the caps are in the form of an integral piece.

6. The evaporator according to claim 1 , wherein the inlet header and the outlet header comprise a first member forming portions of the refrigerant inlet and outlet headers adjacent to the circulating passage and a second member forming the remaining portions of the refrigerant inlet and outlet headers and brazed to the first member, whereby the refrigerant inlet and outlet headers are made integral with each other, each of the caps having engaging lugs engageable with the first member and the second member respectively.

7. A process for fabricating an evaporator, comprising:

forming a refrigerant inlet header, a refrigerant outlet header arranged side by side with respect to the refrigerant inlet header in a front-rear direction, and a refrigerant circulating passage holding the refrigerant inlet and outlet headers in communication with each other therethrough;

joining a cap having a refrigerant inlet to one end of the refrigerant inlet header;

joining a cap having a refrigerant outlet to one end of the outlet header;

joining a pipe joint member having a refrigerant inlet portion in the form of a tube and to be in communication with the refrigerant inlet and a refrigerant outlet portion in the form of a tube and to be in communication with the refrigerant outlet to both the caps of the refrigerant inlet header and the refrigerant outlet header;

inserting a constricted end portion of a refrigerant inlet pipe into the refrigerant inlet portion of the pipe joint member and an end portion of a refrigerant outlet pipe into the refrigerant outlet portion of the pipe joint member; and

brazing the refrigerant inlet portion and the refrigerant outlet portion of the pipe joint member to the refrigerant inlet pipe and the refrigerant outlet pipe respectively at the same time using a high-frequency heating coil in the form of a spectacle-shaped assembly of two annular portions, with one of the annular portions positioned around the refrigerant inlet portion of the pipe joint member and the other annular portion positioned around the refrigerant outlet portion thereof.

8. The process for fabricating an evaporator according to claim 7 , wherein the refrigerant inlet portion is smaller than the refrigerant outlet portion in outside diameter.

9. The process for fabricating an evaporator according to claim 7 , wherein one of the caps and the pipe joint member is provided with a positioning lug projecting toward the other one of the caps and the pipe joint member, and the other one of the caps and the pipe joint member is provided with a positioning recess configured to be fitted with the positioning lug.

10. The process for fabricating an evaporator according to claim 7 , wherein the caps are in the form of an integral piece.