| 摘要 |
A pump (10) comprises a hollow cylindrical body (12) open at one end. A central hole (14) is provided through the closed end of the body (12) with a perimeter wall (16) around the hole (14) of the same height as the boundary wall (18) of the body (12). A left hand thread (22) is provided around the wall (16) and a right hand thread (24) is provided on the inside face of the wall (18). First and second components (26, 38) are provided rotatably mounted respectively on the threads (24 and 22). The components (26, 38) comprise a planar base (28, 40) with upstanding blades (36, 42) thereon. The blades (36) on the first component (26) are orientated for pumping when the rotor turns in one direction and the blades (40) on the second component (38) are orientated for pumping in the same direction when the rotor turns in the opposite direction. The first component (26) is provided with an opening (30) through which the second component (38) can slidably pass in an axial direction such that rotation of one of the components (26, 38) causes rotation of the other component, with one component rising relative to the body to an operative position with the blades thereon extending above the body for pumping when the rotor turns in one direction and the other component descending into the body, and vice versa. |
