| 摘要 |
PURPOSE: A water pump for a vehicle is provided to prevent pump cavitation and reduce pumping loss due to the high-speed rotation of an impeller by varying the rotation speed of the impeller using negative pressure generated in a pumping chamber. CONSTITUTION: A water pump for a vehicle comprises a viscous coupling(24) and a viscous fluid control unit. The viscous coupling generates torque between a pulley and a rotary shaft by the shear force of a viscous fluid. The viscous fluid control unit, which controls the viscous fluid using negative pressure by the centrifugal force of an impeller(20), comprises a cylinder(42), a piston(46), an elastic member(44), and a through hole(48). The cylinder is formed in a rotary shaft(18) and has an opening connected to a fluid chamber(32). The piston is arranged to slide back and forth in the cylinder. The elastic member is arranged between the cylinder and the piston and provides an elastic force for pressing the piston against the fluid chamber. The through hole is axially formed in the center of the rotary shaft for connection with a pumping chamber in which the cylinder and the impeller are placed. |
