Water Pump

A water pump, comprising:

• an upper casing and a lower casing that are coupled to each other to form an impeller accommodating space therein, and have an inlet formed above a central portion of the impeller accommodating space to communicate with the impeller accommodating space and to allow fluid to flow in, a discharge channel formed radially outside the impeller accommodating space to communicate with the impeller accommodating space, and an outlet connected to the discharge channel to discharge the fluid to an outside;
• and
• an impeller that is rotatably accommodated in the impeller accommodating space,
• wherein, in the upper casing, a locking structure part is formed at a position corresponding to the impeller end which is an end of an upper side of a central portion of the impeller, and when a space between an upper surface of an accommodating part, which is an inner surface of an upper side of an impeller accommodating space and an upper surface of the impeller is defined as a first pressure space (P1), and a space between a lower surface of the accommodating part, which is an inner surface of a lower side of the impeller accommodating space, and a lower surface of the impeller is defined as a second pressure space (P2), as the impeller ascends and the impeller end approaches the locking structure part, the pressure in the first pressure space (P1) increases.