Patent ID: 6074184
Filing Date: 2000-06-13
Classification: F04C

Abstract:
A pump for pumping a given fluid material and utilizing a helical seal, said pump comprising:a cylindrical barrel member having a longitudinal axis, said barrel member being closed at the axial opposite ends thereof with closures and having a cylindrical inner peripheral surface between said opposite ends;a core member with a longitudinal axis, with axial opposite ends, and with a cylindrical outer peripheral surface having a diameter slightly smaller than the diameter of the inner peripheral surface of the barrel member, said core member being eccentrically housed in said barrel member with said longitudinal axes of said barrel member and of said core member parallel and radially spaced relative to one another;a helical seal separate from said core member and slidably received on said outer peripheral surface of said core member, said helical seal being received by a helical groove in the inner peripheral surface of said barrel member;said helical seal in its entirety being of helical shape with a number of convolutions;said helical seal in combination with said outer peripheral surface of said core member and said inner peripheral surface of said barrel member defining a helical fluid path between any two adjacent convolutions thereof;a pair of rotary shafts linked to the axial opposite ends of said core member by way of respective eccentric couplings and rotatably held by the respective closures of said barrel member so that said shafts have a common rotational axis parallel to and eccentrically spaced from the longitudinal axis of said barrel member, at least one of said rotary shafts being airtightly extending outwardly through the corresponding closure of said barrel member;said eccentric couplings each including a sheath, with a cylindrical outer surface, rotationally fixed to a respective one of said rotary shafts with the axis of the cylindrical outer surface parallel to and eccentrically spaced from the longitudinal axis of the core member and with the cylindrical outer surface received in a conforming cylindrical inner surface of the core member which conforming inner surface is centered on the longitudinal axis of the core member;a rotary drive unit linked to said rotary shaft airtightly extending through the corresponding closure to drive the sheath fixed to said rotary shaft airtightly extending through the corresponding closure and to thereby cause said core member to eccentrically revolve relative to the inner peripheral surface of the barrel member with the outer peripheral surface of the core member and the inner peripheral surface of the barrel member at each angular position of said rotary shafts having a point at which the spacing between said two peripheral surfaces is a minimum, which point of minimum spacing rotates relative to the barrel member with the rotation of said shafts and the value of which minimum spacing also varies with the rotation of said shafts;an inflow port arranged in an end portion of said barrel member; and an outflow port arranged in another end portion of said barrel member and located axially opposite to said inflow port, whereby the fluid introduced into the barrel member through said inflow port is discharged through said outflow port under pressure due to the eccentric revolution of said core member;said helical seal member being made of an elastically deformable material;said helical seal having a flat radially inner surface held in engagement with the outer peripheral surface of said core member by the elasticity of said helical seal; andsaid helical seal and said helical groove having coengageable generally axially facing side walls which during operation of the pump are urged toward engagement with one another by the pressure of the pumped material, the slidability of the helical seal relative to the outer peripheral surface of the core member and/or the elasticity of the helical seal enabling said coengageable side walls to become tightly sealingly engaged with one another in response to said urging by the pressure of the pumped material.