Patent ID: 6544019
Filing Date: 2003-04-08
Classification: F04C

Abstract:
A positive displacement pump comprising:a) a rotary drive member driven at a speed dependent on a speed of a driving motor; b) a casing; c) a first feed wheel arranged in said casing, said first feed wheel being coupled to said rotary drive member for introducing a torque, and a second feed wheel arranged in said casing, said second feed wheel mating with said first feed wheel; d) said first feed wheel forming, with the walls of said casing and in conjunction with said second feed wheel, a delivery space comprising a low-pressure side connected to a pump inlet port and a high-pressure side connected to a pump outlet port; wherein:e) limiting delivery of said pump is achieved by using a magnetic hysteresis clutch which couples said rotary drive member to said first feed wheel for transmitting said torque; f) an input half of said magnetic clutch is non-rotatably connected to said rotary drive member, and an output half of said magnetic clutch is non-rotatably connected to said first feed wheel; g) and said magnetic clutch is designed with regard to a limiting torque, such that when said output half reaches a speed predefined by the design and without adjusting said input half and said output half relative to each other, said predefined speed increases more slowly than the speed of said input half when said input half exceeds said predefined speed, wherein said predefined speed is less than a maximum operating speed of said input half.