Pump

Abstract

An inner rotor (a drive side) includes a plurality of slots. An outer rotor (a driven side) includes a plurality of pendulum retaining grooves. Each of pendulums includes a head section swingably fitted into a corresponding one of the pendulum retaining grooves and a body section slidably fitted into the corresponding one of the slots. A torque transmission surface of the body section includes a straight line section and a curved section. At a reference angle position at which a perpendicular line orthogonal to an eccentric direction becomes parallel to the corresponding one of the slots, the straight line section makes a surface contact on a torque-transmission-side side surface to start a torque transmission. Until a torque transmission end point, the curved section contacts on opening edge of the corresponding one of the slots. A curved section profile is set to make mutually equal angular velocities between the two rotors.

What is claimed is: 
     
         1 . A pump comprising:
 a cylindrical outer rotor having an inner peripheral surface on which a plurality of pendulum retaining grooves are formed, each pendulum retaining groove being of a letter C shape in cross section and being extended in an axial direction of the pump;   an inner rotor disposed at an inner peripheral side of the outer rotor eccentrically to the outer rotor and having a plurality of slots formed on an outer peripheral surface of the inner rotor in a radial direction of the pump; and   a plurality of pendulums, each pendulum having: a head section of a substantially circular shape in cross section slidably fitted into a corresponding one of the pendulum retaining grooves; and a body section of a substantially triangular shape in cross section connected to the head section via a neck section and slidably fitted into a corresponding one of the slots while contacting on side surfaces of both sides of the corresponding one of the slots and partitioning a space between the outer rotor and the inner rotor into a plurality of chambers, either of the outer rotor or the inner rotor being rotationally driven, wherein   each of the pendulums has a torque transmission surface formed on one side surface of the body section opposed against a torque-transmission-side side surface of a corresponding one of the slots, the torque transmission surface having a profile such that a straight line section and a curved section extended from one end of an outer peripheral side of the straight line section to a side portion of the neck section are continued,   the straight line section has a profile such that the straight line section makes a surface contact on the torque-transmission-side side surface of the corresponding one of the slots, at a reference angle position at which a perpendicular line orthogonal to an eccentric direction of the inner rotor and passing through a center of the inner rotor and the torque-transmission-side side surface of the corresponding one of the slots are made parallel to each other, and   the curved section has a profile such that, at least, during a predetermined torque transmission angle including an angle into which 360° is equally divided by the number of pendulums, the curved section continues the contact on an opening edge of the torque-transmission-side side surface of the corresponding one of the slots and maintains rotational angles of both of the rotors mutually equally.   
     
     
         2 . The pump as claimed in  claim 1 , wherein the inner rotor is rotationally driven, the outer rotor is driven, and the curved section is extended from the straight line section toward a reverse direction side to a rotation direction of the inner rotor and the reference angle position is a point at which the torque transmission is started. 
     
     
         3 . The pump as claimed in  claim 1 , wherein the outer rotor is rotationally driven, the inner rotor is driven, and the curved section is extended from the straight line section toward a forward side of a rotation direction of the inner rotor and the reference angle position is a point at which the torque transmission is ended. 
     
     
         4 . The pump as claimed in  claim 1 , wherein the curved section is projected and extended from a virtual plane connecting an outer peripheral surface of the head section and a terminal outer surface of an inner peripheral side of the body section. 
     
     
         5 . The pump as claimed in  claim 1 , wherein the curved section is constituted by a projection section projected toward a side direction from a connecting section between the body section and the neck section and a recessed section is disposed at a position of the inner peripheral surface of the outer rotor adjacent to each of the pendulum retaining grooves to avoid an interference of the outer rotor against the projection section. 
     
     
         6 . The pump as claimed in  claim 1 , wherein the opening edge at the torque-transmission-side side surface of each of the slots which is contacted on the curved section of the corresponding one of the pendulums is rounded.