Patent ID: 8425210

Claim:
A variable-eccentricity vane pump ( 1 ) comprising a rotor ( 5 ) fitted with blades; an adjusting ring ( 4 ) housing said rotor ( 5 ); and elastic means ( 6 ) for forcing said adjusting ring ( 4 ) into a maximum-eccentricity position with respect to said rotor ( 5 ); said pump being characterized by comprising a first sliding member ( 12 ) connected to said adjusting ring ( 4 ) and which slides in fluidtight manner inside a first chamber ( 9 ) connected hydraulically to a delivery conduit of the pump; and a second sliding member ( 13 ) connected to said adjusting ring ( 4 ) and which slides in fluidtight manner inside a second chamber ( 10 ) connected hydraulically to a delivery conduit of the pump; said first sliding member ( 12 ) being connected to said adjusting ring ( 4 ) on the opposite side to said elastic means ( 6 ) and said second sliding member ( 13 ); and said second chamber ( 10 ) being smaller than said first chamber ( 9 ), and comprising a drain opening ( 11 ) formed in a lateral wall ( 10 a ) on which said second sliding member ( 13 ) slides.