Screw water pump with inner housing and outer housing

A water pump comprising:

• an outer housing having a shape of a container with an open upper side, and including an inlet part positioned at a lower end and communicating with an inner space for a fluid to be introduced therein, and an outlet part positioned at a side of an upper end and communicating with the inner space for the fluid to be discharged therethrough;
• an inner housing having a shape of a container with an open lower side, including a communication hole positioned at an upper end and communicating the inside and outside of the inner housing with each other, and inserted into the outer housing for the communication hole to communicate with the outlet part;
• a thrust key inserted into and coupled to an inner lower end of the outer housing;
• and
• a first screw and a second screw, inserted into the inner housing, having lower ends supported by the thrust key, and engaged with each other to be rotated together,
• wherein a plurality of communication holes are positioned in the inner housing, and the plurality of communication holes are spaced apart from each other along a circumference of the upper end of the inner housing, and positioned toward the upper and lateral sides,
• a plurality of ribs protrude from an outer surface of a second side wall of the inner housing in a vertical direction, and the plurality of ribs are spaced apart from each other along a circumference of the second side wall,
• the upper end of the inner housing includes an upper frame having a shape of a skeleton in which parts other than the plurality of communication holes are connected with each other, and
• the upper frame is integrally connected with the plurality of ribs.