Plate stacking type heat exchanger

A heat exchanger comprising:

• a heat exchanger core through which a first heating medium flows;
• and a case covering the heat exchanger core, the heat exchanger being configured to exchange heat between the first heating medium and a second heating medium flowing between the outside of the heat exchanger core and the inside of the case, wherein
• the heat exchanger core includes a core unit in which a plurality of heat exchanger plates each obtained by laying a first plate member and a second plate member on top of each other are stacked in a stacking direction,
• each of the heat exchanger plates includes a flow path forming portion and a header portion,
• each of the flow path forming portions includes a plurality of flow path bulging portions that bulges outward of the heat exchanger plate and forms a heat exchange flow path of the first heating medium therein,
• each of the header portions includes a communication hole communicating with the header portion of the adjacent heat exchanger plate, and a flow path forming portion-side expanded portion expanding from the communication hole toward the flow path forming portion,
• each of the flow path forming portion-side expanded portions communicates with a plurality of the heat exchange flow paths,
• the each of the header portions includes either a header bulging portion bulging outward or a header flat portion that is flat, and in the core unit, the header bulging portion of the respective heat exchanger plate and the header flat portion of the adjacent heat exchanger plate are stacked in such a manner as to face each other,
• each of the flow path bulging portions is in contact with ether a corresponding header bulging portion or the header bulging portion of the adjacent heat exchanger plate,
• the plurality of flow path bulging portions includes:
• a plurality of first flow path bulging portions bulging outward from the first plate member and extending in a first oblique direction between a circulation direction of the heat exchanger core and a width direction of the heat exchanger core, and
• a plurality of second flow path bulging portions bulging outward from the second plate member and extending in a second oblique direction between the circulation direction and the width direction, the second oblique direction intersecting the first oblique direction, and
• each of the plurality of first flow path bulging portions and each of the plurality of second flow path bulging portions overlaps at a first upstream end of the each of the plurality of first flow path bulging portions in the first oblique direction and at a second downstream end of the each of the plurality of second flow path bulging portions in the second oblique direction.