Patent ID: 7845922

Claim:
A vane pump comprising: a pump housing ( 10 ); a rotor ( 20 ) rotatably contained in the pump housing having a rotational axis ( 13 ); a drive shaft ( 12 ) rotatably driving the rotor ( 20 ); a plurality of grooves ( 24 ) distributed over the rotor ( 20 ) on its circumference, the plurality of grooves ( 24 ) extending at least essentially radially in relation to the rotation axis ( 13 ) of the rotor ( 20 ); a vane-shaped delivery element ( 26 ) guided in each of the plurality of grooves ( 24 ) in sliding fashion, the delivery elements ( 26 ) delimiting radially inner internal regions ( 25 ) in the grooves ( 24 ) of the rotor ( 20 ); a circumference wall ( 18 ) of the pump housing ( 10 ) encompassing the rotor ( 20 ) and extending eccentrically in relation to the rotation axis ( 13 ) of the rotor ( 20 ), against which wall ( 18 ) the radially outer ends of the delivery elements ( 26 ) rest; housing end walls ( 14 , 16 ) of the pump housing ( 10 ) adjoining the rotor ( 20 ) in the direction of its rotation axis ( 13 ), whereby the rotating motion of the rotor ( 20 ) causes the delivery elements ( 26 ) to deliver medium from a suction region to a pressure region that is offset from it in the rotation direction ( 21 ) of the rotor ( 20 ); and at least one annular groove ( 38 ; 381 , 382 ; 383 , 384 ) that extends over at least a part of the circumference of the rotor ( 20 ) is provided, which is connected to the internal region ( 25 ) of at least two of the grooves ( 24 ) of the rotor ( 20 ), wherein the at least one annular groove ( 38 ; 381 , 382 ; 383 , 384 ) is situated in at least one end surface ( 201 , 202 ) of the rotor ( 20 ) facing one of the housing end walls ( 14 , 16 ) and the at least one annular groove ( 38 ; 381 , 382 ; 383 , 384 ) is connected to the pressure region, wherein said pressure region includes a pressure opening ( 32 ) and a pressure groove in one of said housing end walls, and said pressure opening feeds directly into said pressure groove, wherein said suction region includes a suction opening ( 28 ) and a suction groove ( 30 ) in one of said housing end walls, and said suction opening feeds directly into said suction groove, wherein either a connecting groove ( 40 ) or a bore extends from the pressure groove to the annular groove and forms a connection between the pressure groove and the annular groove, and wherein either the connecting groove ( 40 ) or the bore is substantially tangential to both the pressure groove and the annular groove.