Heat storage tank

A heat storage tank, comprising:

• a tank body for thermally insulating and storing a fluid;
• an elbow pipe member defining an introduction passage communicating with the tank body, the elbow pipe member including a first cylinder portion having an introduction port for introducing the fluid, and a second cylinder portion having a discharge port from which the fluid introduced from the introduction port is injected into the tank body, the first cylinder portion and the second cylinder portion being connected to have a corner portion therebetween;
• a discharge pipe member defining a discharge passage having an introduction port from which the fluid in the tank body is introduced to be discharged outside the tank body through the discharge passage;
• and
• a step portion disposed in the elbow pipe member around a position where an axial line of the first cylinder portion and an axial line of the second cylinder portion are substantially crossed with each other, wherein:
• the step portion has a protrusion end surface protruding toward the corner portion, a collision surface extending from the protrusion end surface, to which the fluid flowing from the first cylinder portion collides, and a guide surface extending from the protrusion end surface for guiding the fluid flowing from the first cylinder portion toward the discharge port in the second cylinder portion.