Refrigerant evaporator

Abstract

A refrigerant evaporator includes: a first heat exchange part in which refrigerant flows; a second heat exchange part in which the refrigerant flows; a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part; a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; and a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank. A clearance is defined among the first tank, the second tank, and the third tank. At least one of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage to discharge water trapped in the clearance.

What is claimed is: 
     
         1 . A refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant, the refrigerant evaporator comprising:
 a first heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant;   a second heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part;   a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part;   a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part; and   a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank, wherein   a clearance is defined among the first tank, the second tank, and the third tank, and   each of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage to discharge water trapped in the clearance.   
     
     
         2 . The refrigerant evaporator according to  claim 1 , wherein
 the drainage passage has an outlet port located below the clearance.   
     
     
         3 . The refrigerant evaporator according to  claim 1 , wherein
 the drainage passage is an arc-shaped water passage.   
     
     
         4 . The refrigerant evaporator according to  claim 1 , wherein
 the drainage passage is a straight-shaped water passage.   
     
     
         5 . The refrigerant evaporator according to  claim 1 , wherein
 a cross-section area of an outlet port of the drainage passage is more than or equal to a cross-section area of an inflow port of the drainage passage.   
     
     
         6 . The refrigerant evaporator according to  claim 1 , wherein
 a cross-section area of an inflow port of the drainage passage is larger than a cross-section area of a narrowest clearance between the first tank and the second tank.   
     
     
         7 . A refrigerant evaporator in which heat is exchanged between a fluid to be cooled and a refrigerant, the refrigerant evaporator comprising:
 a first heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant;   a second heat exchange part in which the refrigerant flows to exchange heat between the fluid to be cooled and the refrigerant, the second heat exchange part being arranged to oppose the first heat exchange part;   a first tank arranged below the first heat exchange part to distribute the refrigerant to the first heat exchange part;   a second tank arranged below the second heat exchange part to collect the refrigerant flowing through the second heat exchange part;   a connection part that connects the first tank and the second tank to each other; and   a third tank joined to the first tank and the second tank to introduce the refrigerant collected by the second tank to the first tank, wherein   at least one opening is defined in the connection part, and   each of a joint portion between the first tank and the third tank and a joint portion between the second tank and the third tank defines a drainage passage located below the opening of the connection part to discharge water passing through the opening.   
     
     
         8 . The refrigerant evaporator according to  claim 7 , wherein
 a cross-section area of an inflow port of the drainage passage is larger than an opening area of the opening.   
     
     
         9 . The refrigerant evaporator according to  claim 1 , wherein
 the drainage passage defined in the joint portion between the first tank and the third tank has an inflow port communicated with the clearance, and   the drainage passage defined in the joint portion between the second tank and the third tank has an inflow port communicated with the clearance.   
     
     
         10 . The refrigerant evaporator according to  claim 7 , wherein
 the drainage passage defined in the joint portion between the first tank and the third tank has an inflow port communicated with a lower space of the opening, and   the drainage passage defined in the joint portion between the second tank and the third tank has an inflow port communicated with the lower space of the opening.