Patent ID: 7799074

Claim:
A rotary displacement pump comprising: a casing ( 2 ) in which there are a pumping chamber ( 4 ) and a radial fluid inlet ( 20 ) and outlet ( 21 ) for said pumping chamber ( 4 ); an outer gear ( 13 ) with an internal toothset ( 16 ) positioned inside said pumping chamber ( 4 ) and displaying the shape of a squirrel cage provided with two end plates ( 14 , 15 ) which are connected by longitudinal bars that form said internal toothset, said outer gear ( 13 ) being at least partially dismantleable; rotation means ( 11 , 12 ) allowing said outer gear ( 13 ) to rotate inside said pumping chamber ( 4 ) about a first axis (A 13 ) and comprising at least one bearing ( 11 , 12 ) positioned centrally in an end plate ( 14 , 15 ) of said outer gear ( 13 ); an inner gear ( 9 ), housed inside said outer gear ( 13 ) and provided with an external toothset ( 9 D) meshing with said internal toothset ( 16 ) of the outer gear ( 13 ), said inner gear ( 9 ) rotating about a second axis (A 8 ), parallel to and distant from said first axis (A 13 ), and said external toothset ( 9 D) comprising a number of teeth lower by one unit than the number of teeth of the internal toothset of said outer gear ( 13 ); and a motor ( 3 ) for driving the rotation of said inner gear ( 9 ) about said second axis (A 8 ), wherein: said pumping chamber ( 4 ) comprises a removable wall ( 10 ) capable of being fixed to said casing ( 2 ) to close off said pumping chamber ( 4 ), and a bearing ( 12 ) of said rotation means is positioned in said removable wall ( 10 ); a bearing ( 11 ) of said rotation means is positioned in a fixed wall ( 5 ) of said pumping chamber ( 4 ); said casing ( 2 ) comprises a housing ( 2 M) for said motor ( 3 ) and said fixed wall ( 5 ) separates said housing ( 2 M) from said pumping chamber ( 4 ); the shaft ( 8 ) of the motor ( 3 ) driving the rotation of the inner gear ( 9 ) passes through said fixed wall ( 5 ) inside said bearing ( 11 ); and said shaft ( 8 ) of the motor ( 3 ) is hollow and through it there passes, with clearance, a tie rod ( 22 ) used to fix said removable wall ( 10 ) to said casing ( 2 ).