Radial piston pump

A radial piston pump comprising,

• a housing in which a cylindrical cylinder chamber is formed,
• a pintle portion provided within said cylinder chamber in such a manner that the center axis of said pintle portion is offset from a center axis of said cylinder chamber,
• a rotor rotatably mounted on said pintle portion, said rotor having three working chambers therein such a manner that intervals between each adjacent pair of said working chambers are equal to each other,
• a rotor slidably provided within said working chambers, and
• a bearing provided within said cylinder chamber in such a manner that an outer race of said bearing is held by said housing and an inner race of said bearing is functionally connected with said piston, wherein
• said pintle portion has a discharge groove and a suction groove at an outer surface of said pintle portion, and said pintle portion has a preliminary expanding portion at a front edge side of said suction groove formed such that a pressure within said working chamber is gradually reduced before said working chamber connects to said suction groove, and so that a forcing point at which a pressing force caused by said pistons is focused is moved gradually.

A radial piston pump comprising,

• a housing in which a cylindrical cylinder chamber is formed,
• a pintle portion provided within said cylinder chamber in such a manner that a center axis of said pintle portion is offset from a center axis of said cylinder chamber,
• a rotor rotatably provided on said pintle portion, said rotor having three working chambers therein in such a manner that intervals between adjacent ones of said working chambers is equal to each other,
• a piston slidably provided within each said working chamber so that a top end of said piston is functionally connected with an inner surface of said cylinder chamber so that said piston reciprocates within said working chamber,
• a suction groove formed on an outer surface of said pintle portion in such a manner that said working chamber will face to said suction groove at certain orientations and,
• a discharge groove formed on an outer surface of said pintle portion at an opposite side of said suction groove in such a manner that said working chamber will face to said discharge groove at certain orientations, wherein
• said pintle portion includes means for forming a first delay angle at a front edge side of said suction groove such that a pressure within said working chamber is preliminarily reduced before said working chamber connects with said discharge groove, and
• said pintle portion includes means for forming a second delay angle at a front edge side of said suction groove such that a pressure within said working chamber is preliminarily reduced before said working chamber connects with said suction groove so that a forcing point at which a pressing force caused by said pistons is focused is gradually moved in accordance with a rotation of said rotor.

A radial piston pump for pumping fluid comprising:

• a housing in which a cylinder chamber is formed,
• a rotor rotatably provided within said cylinder chamber said rotor having a working chamber formed therein,
• a pintle portion within said cylinder chamber which has a discharge groove on its outer surface,
• a piston reciprocably provided within said working chamber,
• suction means, for sucking said fluid, formed to face said working chamber at certain positions of said rotor,
• discharge means for discharging said fluid, formed to face said pintle portion so that said working chamber will face said discharge groove at certain positions of said rotor,
• means for forming a first delay angle at a front side of said suction means, said first delay angle being between a first portion, at which said piston is at a bottom dead point within said working chamber, and a second portion, at which a front edge of said working chamber contacts said suction means, said first delay angle being an amount that a forcing point at which a pressing force caused by said piston is focused is gradually moved.