Patent ID: 7107787

Claim:
An evaporator comprising first and second heat exchange units each comprising: a plurality of heat exchange passages extending in the vertical direction, wherein the plurality of heat exchange passages is laminated in multistage in the horizontal direction, and wherein the heat exchange passages have a refrigerant flowing therein; and upper and lower tanks respectively provided at both upper and lower ends of the plurality of heat exchange passages in multistage, wherein the upper and lower tanks join the heat exchange passages in multistage and distribute the refrigerant; wherein the first and second heat exchange units are arranged in two layers in an air flow direction; wherein the first and second heat exchange units are connected to each other so that the refrigerant flows through the first heat exchange unit and then through the second heat exchange unit; wherein the first heat exchange unit, at the inlet side of the evaporator, has at least two flow paths that comprise: a first descending flow path in which the refrigerant flows from the upper tank of the first heat exchange unit to the lower tank of the first heat exchange unit; and a first ascending flow path in which the refrigerant flows from the lower tank of the first heat exchange unit to the upper tank of the first heat exchange unit; wherein the second heat exchange unit, at the outlet side of the evaporator, has at least two flow paths that comprise: a second ascending flow path in which the refrigerant flows from the lower tank of the second heat exchange unit to the upper tank of the second heat change unit; and a second descending flow path in which the refrigerant flows from the upper tank of the second heat exchange unit to the lower tank of the second heat exchange unit; wherein, in the first heat exchange unit, the number of heat exchange passages in the first ascending path in which the refrigerant ascends is less than the number of heat exchange passages in the first descending path in which the refrigerant descends; and wherein, in the second heat exchange unit, the number of heat exchange passages in a most downstream path is greater than the number of heat exchange passages in a path immediately upstream of the most downstream path.