Screw type pump
AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorsMamoru Yoshikawa, Taketoshi Satoh
Life of this patent
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Abstract
A screw pump having a pair of screw rotors meshed with each other and rotatably supported in a housing having an intake port provided at one end and a piston movably provided at the other axial end of the housing, which piston defines a discharge port in cooperation with the housing. The movement of the piston in a direction substantially perpendicular to the axes of the screw rotors enables the distance between a discharge starting position of the discharge port and the intake port to be varied, so that the internal compression ratio can be varied. This arrangement ensures that the size of the housing will not be increased and any disadvantage due to the difference in thermal expansion along the length of the housing can be overcome.
Claims14
A screw type pump having a pair of screw rotors meshed with each other and rotatably supported in a housing, comprising
- a piston which is provided on a side of the housing having an intake port provided at one axial end for movement between a high-compression position inwardly in a moving direction perpendicular to an axis of the screw rotors and a low-compression position outwardly in the moving direction, said piston defining a discharge port in cooperation with a lead-out section provided at the other axial end of the housing, that portion of said piston which faces into the housing being formed so that a discharge starting position of the discharge port at the time when said piston is in said low-compression position is closer to the intake port than a discharge starting position of the discharge port at the time when said piston is in said high-compression position, and
- a back pressure chamber which a back of the piston faces, and a communication hole provided in the piston for permitting communication of the back pressure chamber with the discharge port.
A screw type pump having a pair of parallel screw rotors meshed with each other and rotatably supported to extend axially in a generally cylindrical housing, comprising
- the housing having an intake port on one axial end and a lead-out discharge section at the other axial end,
- a piston provided on a side of said housing between said axial ends for movement between a high-compression inwardly located position in a moving direction perpendicular to the housing and a low-compression outwardly located position in the moving direction, said piston defining a discharge port in cooperation with a lead-out section provided at the other axial end of the housing, said piston having an inwardly facing portion shaped to closely fit outer extremes of the screw rotors to form a discharge starting position of the discharge port with said piston in said high-compression inward position which is further from intake port than a discharge starting position of the discharge port with said piston in said low-compression outward position spaced from the screw rotors, and
- a back pressure chamber in said housing on the outside of the piston, and a communication hole provided in the piston for permitting communication of the back pressure chamber with the discharge port.
Dependencies are inferred from the claim text.