Stack type heat exchanger

A stack heat exchanger comprising:

• a plurality of first plates;
• and
• a plurality of second plates, wherein
• a first flow path is defined between one of the plurality of second plates and one of the plurality of first plates adjacent to one of the plurality of second plates on one side in the stacking direction of one of the plurality of first plates and one of the plurality of second plates, a first fluid flowing through the first flow path,
• a second flow path is defined between the one of the plurality of second plates and another one of the plurality of first plates adjacent to the one of the plurality of second plates on an other side in the stacking direction, a second fluid flowing through the second flow path, a pressure of the second fluid being lower than a pressure of the first fluid,
• each of the plurality of first plates has:
• a first main body that defines the first flow path and the second flow path;
• and
• a first communicating hole formed in the first main body to define a tank space by which the first flow paths adjacent to each other through the second flow path communicate with each other in the stacking direction,
• each of the plurality of second plates has:
• a second main body that defines the first flow path and the second flow path;
• and
• a second communicating hole formed in the second main body to define the tank space,
• at least one of the plurality of first plates and one of the plurality of second plates has a protrusion protruding from at least one of the first main body and the second main body toward the first flow path, the protrusion being located at a peripheral portion of the tank space in the first flow path,
• the one of the plurality of first plates and the one of the plurality of second plates are joined to each other through the protrusion,
• each protrusion has a top portion which is a joining portion between one of the plurality of first plates and one of the plurality of second plates, and a side wall portion which is continuous with the top portion, the side wall portion being located between the top portion and the main body in the stacking direction,
• a part of the side wall portion adjacent to the tank space has a thick structure portion, an entire thickness of the thick structure portion in a direction perpendicular to the stacking direction being thicker than a thickness of a partition part that partitions the first flow path and the second flow path in each of the first main body and the second main body,
• each of the plurality of first plates has a first tube portion extending toward the one side in the stacking direction,
• each of the plurality of second plates has a second tube portion extending toward the other side in the stacking direction,
• the second tube portion of one of the plurality of second plates and the first tube portion of one of the plurality of first plates directly adjacent to one of the plurality of second plates on the other side in the stacking direction overlap with each other at overlapping portions, the tank space being formed by joining the overlapping portions to each other,
• each of the plurality of second plates has the protrusion,
• each of the plurality of first plates and each of the plurality of second plates are made of a metal material,
• the part of the side wall portion is connected to the second tube portion and joined to the first tube portion through a brazing material,
• the thick structure portion is defined by the part of the side wall portion, the brazing material in contact with the part of the side wall portion, and a part of the first tube portion in contact with the brazing material, and
• the thick structure portion is located adjacent to a joining portion at which a top portion of the protrusion of the first plate and a top portion of the protrusion of the second plate are joined to each other.