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US 8,142,173 B2Granted
Variable displacement vane pump
AssigneeHitachi, Ltd.
InventorsKoji Saga, Yasushi Watanabe, Hideaki Ohnishi
Life of this patent
Estimating the term…
Abstract
In a variable displacement vane pump employing a cam ring, a pump rotor, and a plurality of vanes, each slidably fitted into the rotor, a biasing member is provided to force the cam ring in a direction that a geometric center of an inner peripheral surface of the cam ring and a rotation center of the rotor are spaced apart from each other. A force, by which the cam ring can be oscillated against the biasing member in accordance with a buildup of a pressure in a pump discharge portion, acts on the inner peripheral surface of the cam ring.
Claims20
A variable displacement vane pump comprising:
- a rotor driven by an internal combustion engine;
- a cam ring configured to accommodate therein the rotor and further configured to oscillate about a fulcrum of oscillating motion along two axially opposed sidewalls facing both sides of the cam ring respectively;
- a plurality of vanes, each of which is fitted into the rotor to slide from the rotor toward an inner peripheral surface of the cam ring and set to be kept in abutted-engagement with the inner peripheral surface of the cam ring, the vanes being configured to define a plurality of working chambers in cooperation with an outer peripheral surface of the rotor, the inner peripheral surface of the cam ring, and the two axially opposed sidewalls;
- a biasing member configured to force the cam ring in a direction that a geometric center of the inner peripheral surface of the cam ring and a rotation center of the rotor are spaced apart from each other;
- and
- an inlet portion and a discharge portion both formed in at least one of the two axially opposed sidewalls, the inlet portion being configured to open into a first group of working chambers of the plurality of working chambers so as to extend over the first group of working chambers within an area where volumes of the first group of working chambers increase, and the discharge portion being configured to open into a second group of working chambers of the plurality of working chambers so as to extend over the second group of working chambers within an area where volumes of the second group of working chambers decrease,
- wherein an only force, acting on the inner peripheral surface of the cam ring to oscillate the cam ring against the biasing member, is a pressure in the discharge portion.
4 more elements
A variable displacement vane pump comprising:
- a rotor driven in synchronism with rotation of an internal combustion engine;
- a cam ring configured to accommodate the rotor in an inner peripheral surface of the cam ring and further configured to oscillate about a fulcrum of oscillating motion between two axially opposed sidewalls facing both sides of the cam ring respectively;
- a plurality of vanes, each of which is fitted into the rotor to slide from an outer peripheral surface of the rotor toward the inner peripheral surface of the cam ring, the vanes being configured to define a plurality of working chambers in cooperation with the outer peripheral surface of the rotor, the inner peripheral surface of the cam ring, and the two axially opposed sidewalls;
- a biasing member configured to force the cam ring in a direction that a volume difference between a volume of the largest working chamber of the plurality of working chambers and a volume of the smallest working chamber of the plurality of working chambers increases;
- and
- an inlet portion and a discharge portion both formed in at least one of the two axially opposed sidewalls, the inlet portion being configured to open into a first group of working chambers of the plurality of working chambers so as to extend over the first group of working chambers within an area where volumes of the first group of working chambers increase, and the discharge portion being configured to open into a second group of working chambers of the plurality of working chambers so as to extend over the second group of working chambers within an area where volumes of the second group of working chambers decrease,
- wherein the fulcrum of oscillating motion of the cam ring is laid out to be offset in a biasing direction of the biasing member within an opening range of the discharge portion wherein an only force, acting on the inner peripheral surface of the cam ring to oscillate the cam ring against the biasing member, is a pressure in the discharge portion.
4 more elements
A variable displacement vane pump comprising:
- a rotor rotated by a drive source;
- a cam ring configured to accommodate therein the rotor and further configured to oscillate about a fulcrum of oscillating motion, while being kept in sliding-contact with two axially opposed sidewalls facing both sides of the cam ring respectively;
- a plurality of vanes, each of which is fitted into the rotor to slide from the rotor toward an inner peripheral surface of the cam ring, the vanes being configured to define a plurality of working chambers in cooperation with an outer peripheral surface of the rotor, the inner peripheral surface of the cam ring, and the two axially opposed sidewalls;
- a biasing member configured to force the cam ring in a biasing direction that a rate of change of a volume of each of the plurality of working chambers increases;
- and
- an inlet portion and a discharge portion both formed in at least one of the two axially opposed sidewalls, the inlet portion being configured to open into a first group of working chambers of the plurality of working chambers so as to extend over the first group of working chambers within an area where volumes of the first group of working chambers increase, and the discharge portion being configured to open into a second group of working chambers of the plurality of working chambers so as to extend over the second group of working chambers within an area where volumes of the second group of working chambers decrease,
- wherein an integral ∫S2dt of a second segmented pressure-receiving area of the inner peripheral surface of the cam ring, extending in the biasing direction of the biasing member with respect to the fulcrum of oscillating motion, for a given cycle, is less than an integral ∫S1dt of a first segmented pressure-receiving area of the inner peripheral surface of the cam ring, extending in the direction opposite to the biasing direction of the biasing member with respect to the fulcrum of oscillating motion, for the given cycle wherein an only force, acting on the inner peripheral surface of the cam ring to oscillate the cam ring against the biasing member, is a pressure in the discharge portion.
4 more elements
Dependencies are inferred from the claim text.