Abstract: A hydraulic pump (6) comprising: a housing (20) having first and second inlets (100a, 100b) and first and second outlets (102a, 102b); a crankshaft (4) extending within the housing (20) and having axially offset first and second cams (62, 64); first and second groups (30, 32) of piston cylinder assemblies provided in the housing (20), each of the said groups (30, 32) having a plurality of piston cylinder assemblies having a working chamber of cyclically varying volume and being in driving relationship with the crankshaft (4); one or more electronically controllable valves (40) associated with the first and second groups (30, 32); and a controller (70) configured to actively control the opening and/or closing of the said electronically controllable valves (40) on each cycle of working chamber volume to thereby control the net displacement of fluid by the first and second groups (30, 32), wherein at least the first group (30) comprises a first piston cylinder assembly in driving relationship with the first cam

Abstract: A hydraulic pump (6) comprising: a housing (20) having first and second inlets (100a, 100b) and first and second outlets (102a, 102b); a crankshaft (4) extending within the housing (20) and having axially offset first and second cams (62, 64); first and second groups (30, 32) of piston cylinder assemblies provided in the housing (20), each of the said groups (30, 32) having a plurality of piston cylinder assemblies having a working chamber of cyclically varying volume and being in driving relationship with the crankshaft (4); one or more electronically controllable valves (40) associated with the first and second groups (30, 32); and a controller (70) configured to actively control the opening and/or closing of the said electronically controllable valves (40) on each cycle of working chamber volume to thereby control the net displacement of fluid by the first and second groups (30, 32), wherein at least the first group (30) comprises a first piston cylinder assembly in driving relationship with the first cam

Abstract: The invention relates to a fluid distribution valve (1, 25, 29, 37, 43), comprising at least a first fluid port (2), a second fluid port (3) and a third fluid port (4). These ports are connecting to a fluid distribution chamber (5). The second fluid port (3) can be selectively connected to the first fluid port (2) and/or the third fluid port (4) through said distribution chamber (5). The second fluid port (3) is arranged between the first fluid port (2) and the third fluid port (4).

Abstract: In open-circuit hydraulic systems (1), the cross-sections of the supply lines (6) and input valves of the hydraulic pump (3) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow (7) of a hydraulic pump (3) is charged by a second, charging pump (2), to a mid-pressure level (7). The cross-sections of the supply flow areas can thus be decreased.

Abstract: In open-circuit hydraulic systems (1), the cross-sections of the supply lines (6) and input valves of the hydraulic pump (3) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow (7) of a hydraulic pump (3) is charged by a second, charging pump (2), to a mid-pressure level (7). The cross-sections of the supply flow areas can thus be decreased.

Abstract: In usual hydraulic pumps, a separate assembly opening is provided for every valve of the hydraulic pump. This design causes sealing problems. It is proposed, that the fluid inlet valve and the fluid outlet valve can be assembled through a common assembly access port. Further, the fluid inlet valve and the fluid outlet valve can be arranged around a common cavity, or even within the same cavity, via the common assembly access port in the fluid working machine's body.

Abstract: The present invention provides a method of controlling a fluid working machine (12) having a plurality of working cylinders (14) having pistons (16) therein and arranged to drive a shaft (18), in which said cylinders are supplied with pressurized working fluid via a manifold (24), the contents of which may be 5 purged by a de-pressurizer taking one of a number for forms such as to allow re-activation of said machine (10).

Abstract: A fluid working machine (1) has several working chambers (5) of cyclically changing volume. For pumping hydraulic fluid, the inlet and outlet valves (8, 9) are electrically actuated. The timing of the actuation of said electrically actuated valves (8, 9) is varied depending on the fluid flow demand.

Abstract: To improve the fluid output flow characteristics (14) of a synthetically commutated hydraulic pump (1), it is suggested to use a plurality of different valve (10) actuation strategies. For every fluid flow demand region I to VI a certain actuation strategy is chosen.

Abstract: When the fluid flow output of a synthetically commutated hydraulic pump is adapted to a given fluid flow demand, pulsations in the fluid output flow of the synthetically commutated hydraulic pump can occur. To avoid such pressure pulsations, it is suggested, to use a set of pre-calculated actuation patterns for actuating the electrically commutated valves of the synthetically commutated hydraulic pump.

Abstract: When employing synthetically commutated hydraulic pumps (1), a time delay between a change in fluid flow demand (15) and the resulting fluid flow output (13) can be observed. It is suggested to use a time evolvement function, taking into account the time evolvement of the fluid flow demand and/or the time evolvement of the pumping strokes, to modify the actuation of the electrically commutated valves.

Abstract: The invention relates to a fluid distribution valve (1, 25, 29, 37, 43), comprising at least a first fluid port (2), a second fluid port (3) and a third fluid port (4). These ports are connecting to a fluid distribution chamber (5). The second fluid port (3) can be selectively connected to the first fluid port (2) and/or the third fluid port (4) through said distribution chamber (5). The second fluid port (3) is arranged between the first fluid port (2) and the third fluid port (4).

Abstract: In usual hydraulic pumps, a separate assembly opening is provided for every valve of the hydraulic pump. This design causes sealing problems. It is proposed, that the fluid inlet valve (67) and the fluid outlet valve (74) can be assembled through a common assembly access port (38).

Abstract: A fluid working machine (1) has several working chambers (5) of cyclically changing volume. For pumping hydraulic fluid, the inlet and outlet valves (8, 9) are electrically actuated. The timing of the actuation of said electrically actuated valves (8, 9) is varied depending on the fluid flow demand.

Abstract: When the fluid flow output of a synthetically commutated hydraulic pump is adapted to a given fluid flow demand, pulsations in the fluid output flow of the synthetically commutated hydraulic pump can occur. To avoid such pressure pulsations, it is suggested, to use a set of pre-calculated actuation patterns for actuating the electrically commutated valves of the synthetically commutated hydraulic pump.

Abstract: To improve the fluid output flow characteristics (14) of a synthetically commutated hydraulic pump (1), it is suggested to use a plurality of different valve (10) actuation strategies. For every fluid flow demand region I to VI a certain actuation strategy is chosen.

Abstract: The present invention provides a method of controlling a fluid working machine (12) having a plurality of working cylinders (14) having pistons (16) therein and arranged to drive a shaft (18), in which said cylinders are supplied with pressurised working fluid via a manifold (24), the contents of which may be 5 purged by a de-pressuriser taking one of a number for forms such as to allow re-activation of said machine (10).

Abstract: When employing synthetically commutated hydraulic pumps (1), a time delay between a change in fluid flow demand (15) and the resulting fluid flow output (13) can be observed. It is suggested to use a time evolvement function, taking into account the time evolvement of the fluid flow demand and/or the time evolvement of the pumping strokes, to modify the actuation of the electrically commutated valves.

Abstract: In open-circuit hydraulic systems (1), the cross-sections of the supply lines (6) and input valves of the hydraulic pump (3) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow (7) of a hydraulic pump (3) is charged by a second, charging pump (2), to a mid-pressure level (7). The cross-sections of the supply flow areas can thus be decreased.

Abstract: A system for automatically holding a predetermined course in a vehicle with a two-train hydrostatic traction drive, comprising a measurement device (5) for detecting the actual rotational movement of the vehicle around a vertical axis of the vehicle, and for providing a first signal representing the rotational movement. An electronic controller (1) operatively associated with the measurement device (5) to evaluate the first signal to determine the deviation of the first signal from the predetermined course of the vehicle to form a control signal to hydrostatic transmissions of the two-train hydrostatic drive to operate and to provide a course correction.