| 摘要 |
1,196,708. Rotary pumps. WALBRO CORP. June 5, 1968 [June 5, 1967], No.26676/68. Heading F1F. A rotary pump assembly having a pumping chamber including a relief valve means which comprises part of the chamber wall supportable in position by a magnetic force so that at a predetermined pressure within the chamber the said part of the chamber wall is displaced to allow the escape of pressure medium from the chamber. As shown, a rotary radially sliding vane pump comprising a rotor 60, Fig. 5, having radially sliding vanes 80 is eccentrically mounted within a cam-ring insert 83 of magnetic material with the upper faces of the rotor and cam-ring insert covered by a ring 86, Fig.3, also of magnetic material. The ring 83 or the ring 86 both may be magnetized so that the ring 86 is held in sealing contact with the ring 83 to seal the pumping chamber. When the pressure of the pumped medium usually liquid in the chamber exceeds a predetermined value the ring 86 is urged upwardly to break the magnetic seal whence pressure medium escapes from the chamber and passes through a port 90 into the inlet passage 26 of the pump which includes a filter tube 24. The pump is driven by an electric motor 42 through a magnetic coupling consisting of a magnetic disc 50 secured against relative rotation to the motor shaft 44 and a magnetic disc 70 separated from the disc 50 by a membrane 54 and secured against relative rotation to the rotor shaft 62. The discs 50, 70 are a sliding fit on their respective shafts to permit of axial movement of the discs. It is desirable that the breakaway torque between the discs 50, 70 is less than the stall torque of the motor to provide overload protection. |
