Patent ID: 6413066
Filing Date: 2002-07-02
Classification: F04C

Abstract:
Roller vane pump suitable for pumping transmission fluid in an automatic transmission for motor vehicles, in particular a continuously variable transmission, comprising:a pump housing (2); a drivably rotatable carrier (3) having a substantially circular cross section and being located in the interior of the pump housing (2), at its radial periphery being provided with slots (6) that extend in a direction substantially inward from the periphery; a cam ring (5) having a non-circular inner surface (5a) and surrounding the carrier (3) in radial direction; substantially cylindrical roller elements (7) being slidably provided in the slots (6) of the carrier (3), wherein the spaces between the pump housing (2), the carrier (3), the cam ring (5) and the roller elements (7) define pump chambers (8), wherein said pump chambers (8) are divided into cam chambers (8b) and carrier chamber (8a), the cam chambers (8b) ranging from tangential centre planes of the roller elements (7) radially outward, and the carrier chambers (8a) ranging from tangential centre planes of the roller elements (7) radially inward, each carrier chamber (8a) being associated with a leading cam chamber (8b) in rotational direction and a trailing cam chamber (8b) in anti-rotational direction; at least one feed aperture (9) having substantially elongated shape, a long axis of said feed aperture (9) extending in a substantially tangential direction, said feed aperture (9) being arranged in the pump housing (2) such that at least one pump chamber (8) is associated with a feed channel (11) in the pump housing (2) through the feed aperture (9), wherein said feed aperture (9) is divided into an inner feed aperture (9a) and an outer feed aperture (9b) by a ridge (12) having an inner surface (12a) and an outer surface (12b), said surfaces (12a,12b) extending in a substantially axial direction as well as in a substantially tangential direction; and at least one discharge aperture (10) having a substantially elongated shape, a long axis of said discharge aperture (10) extending in a substantially tangential direction, said discharge aperture (10) being arranged in the pump housing (2) such that at least one pump chamber (8) is associated with a discharge channel in the pump housing (2) through the discharge aperture (10), wherein said discharge aperture (10) is divided into an inner discharge aperture (10a) and an outer discharge aperture (10b) by a ridge (12) having an inner surface (12a) and an outer surface (12b), said surfaces (12a,12b) extending in a substantially axial direction as well as in a substantially tangential direction, wherein the outer feed aperture (9b) is provided with an end part (9c) extending in anti-rotational direction, such that at the location of said end part (9c) said pump chamber 8 arrives into communication with said feed aperture (9b) through a slit (14) formed by co-operation between the cam ring (5) and the respective end part (9c), essentially before a fluid flow to the pump chamber (8) starts, whereby the end part (9c) is shaped such that it overlaps a part of the cam ring (5) in axial direction and has a radial width that is significantly less than that of the widest part of the respective aperture (9b).