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AssigneeLucas Industries Limited
InventorThomas Ernest Edwin Roberts
Estimating the term…
A rotary hydraulic pump or motor has a piston-carrying rotor having a face engaging a port plate which includes a high pressure port. A number of by-pass passages enable the rotor bores to communicate with the high pressure port before being in full alignment therewith. A valve arrangement is responsive to the pressures in the high pressure port and in successive ones of the rotor bores to provide that variation of these pressures causes variation of the position, relative to top-dead-center, at which successive rotor bores communicate with the high pressure port via the by-pass passages. The arrangement is such that pressures in the rotor bores and the high pressure port, immediately before they communicate, are maintained substantially equal over a range of pressures.
A rotary hydraulic machine comprising a housing, a rotor within the housing, said rotor having a plurality of bores which open onto a face of the rotor, means, responsive to rotation of the rotor, for causing liquid displacement within said bores to accompany said rotation, a port plate against one face of which said rotor face is engaged, said port plate including a first port with which said bores can successively communicate, a first passage in said port plate, said first passage communicating with said first port and with port means which open on to said port plate face, said port means being spaced from said first port, in a direction of the path of movement of said bores across said port plate face, so that said bores communicate, in use, with said port means before communicating with said first port, said port means extending in said direction of movement, and a control element, responsive to an increase in pressure in said bores, for progressively uncovering said port means in a direction away from said first port, and to an increase in pressure in said first port for progressively covering said port means in a direction towards said first port.
Dependencies are inferred from the claim text.