Abstract: A fluid power system comprises a pump with multiple independently variable outlets (11, 12, 13, 14), each of which is capable of delivering fluid in individually controllable volume units and a plurality of hydraulic loads (15, 16, 18, 20). A system of switching valves is configured to create fluid connections between the pump outlets and the loads. A control system commands both the pump and the switching valves, so as to create valve state combinations to satisfy load conditions as demanded by an operator. The number of pump outlets (11, 12, 13, 14) connected to one or more of the loads (15, 16, 18, 20) is changeable to satisfy the flow required of the load due to the operator demand, each pump outlet being commanded to produce a flow depending on the status of other outlets connected a load to which the outlet is connected and the operator demand for that load.

Abstract: The present invention provides a fluid system (99) comprising a source of hydraulic fluid under pressure supplying a hydraulic fluid consumer (103) together with a valve passing fluid between said source and said fluid consumer (102). A first fluid compliance (105) is situated between said source (100) and said valve (102) and a variable restrictor (110) is provided for varying the cross sectional area available for flow of fluid through said valve (102) and is movable between a first position (A) with a larger said area and a second position (B) with a smaller said area. A bias means (117) biases said restrictor (110) towards said second position while an opening means (Fa) urges said restrictor (110) against said bias (117) when fluid flows through said valve (102) and a damping means (126) damps movement of said restrictor between said first and second positions and provides a resistance which increases with the velocity of displacement of said restrictor (110).

Abstract: The invention concerns a hydraulic steering (1) with a steering motor (8), a steering unit (2) with feedback behavior, a steering member activating the steering unit (2) and a shock valve arrangement (50) between the steering motor (8) and the steering unit (2). It is endeavored to enable changes of the feedback behavior in a simple manner. For this purpose it is ensured that a switchable feedback suppression device (9) is located at the side of the shock valve arrangement (50) facing away from the steering motor (8).

Abstract: The invention relates to a valve actuator (2), comprising a magnetic core (6) with an interspace (8) and at least one bifurcating branch (7), at least one variable magnetic field generating device (16), at least one permanent magnetic field generating device (13) and at least one movable magnetic component (12), wherein the bifurcating branch (7) defines a first region (4) and a second region (5) of said magnetic core (6).

Abstract: If a hydraulic system has several modes of operation, in particular a mode with a high pressure demand (II) and a mode with a high fluid flow demand (II), the hydraulic fluid pump has to be built with an accordingly high fluid flow output. Such a pump is expensive. Therefore it is suggested, to provide two pumps. I.e. a controllable main pump (2) is provided, which supplies the hydraulic consumer (6) during phases (I) of high pressure demand. During phases (II) of high fluid flow demand, normally, relatively low pressures are sufficient. Therefore, it is suggested to provide a parallel boost pump (9), which supplies the hydraulic consumer (6) in addition to the high pressure pump (2), if a high fluid flow is needed. Excess fluid flow output is avoided by controlling the fluid output flow of main pump 2.

Abstract: The invention provides a steering system for a vehicle, a ship etc. The steering system has a steering handle for the operator of the vehicle, a set of signal processors, a sensor which determines a position of the steered element of the vehicle, and a controller which moves the steered element. The steered element could e.g. be the front wheels of a car. The signal processors are adapted to determine an error between the desired position of the steered element and an actual position of the steered element. In order to make the steering system more fault tolerant, the error signal is amplified based on the speed by which the steering handle is moved, and an error in the sensor therefore becomes less critical. The invention further provides a steering method, a steering control unit and a vehicle provided with a steering system of the mentioned kind.

Abstract: A control device (1) for a hydrostatic steering motor comprises supply and return pump and tank connections (P, T), a slide valve arrangement in which inner and outer slide element sleeves are rotatable relative to each other to both sides of a neutral position through a limited small angle, said sleeves mutually forming controlled supply and return passages connected to said motor having supply and return throttles which are closed when said sleeves are in a neutral position, bypass throttle means (7) between said pump and tank connections (P, T) being open when said sleeves are in a neutral position, said bypass throttle means (7) having a set of at least two variable orifices connected in series. In such a device the noise should be reduced when a higher supply pressure of hydraulic fluid is used.

Abstract: The invention concerns a hydraulic steering (1) with a steering unit (2) with feedback behavior, a steering motor (8) connected to the steering unit (2) via working pipes (L, R), a steering member (6) and a feedback suppression device (9), which is located in at least one working pipe (L, R). It is endeavored to change the feedback behavior of such a steering in a simple manner. For this purpose, the feedback suppression device (9) has a valve arrangement (10) with hydraulic control inlet (C).

Abstract: The invention concerns a hydraulic valve arrangement (1) with a supply connection arrangement comprising a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement comprising two working connections (A, B), which can be connected to a motor (4), a directional valve arrangement (5) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a compensation valve (15) acted upon in a first activation direction by a pressure in a first pressure chamber (33), which is connected to a load-sensing pipe (LS), and, if required, by a spring (32), and in a second activation direction opposite to the first activation direction by a pressure downstream of the directional valve arrangement (5), said pressure acting in a second pressure chamber (34), the compensation valve (15) having an inlet (14) and an outlet (19).

Abstract: The invention relates to a hydraulic machine comprising a housing section with a housing, a commutation section and a gear wheel section, the gear wheel section comprising a gear wheel set with an internally toothed gear ring and an externally toothed gear wheel, which engage each other and form working chambers that are connected to at least one inlet connection and at least one outlet connection via the commutation section that comprises a rotary slide valve and a valve plate. It is endeavored to provide such a hydraulic machine that requires only little space. For this purpose, a sealing is arranged between the rotary slide valve and the housing.

Abstract: A joystick (1) comprising a substantially stationary part (4) and a movable part (3) adapted to be manipulated by an operator. The joystick further comprises a sensor device adapted to detect a position of the movable part (3) relatively to the substantially stationary part (4), the sensor device comprising a magnet arrangement comprising one or more magnets (9) and defining a predetermined magnetic field, and a magnetic detector being adapted to detect a magnetic flux and to generate a corresponding output. The magnet arrangement or the magnetic detector is arranged on the substantially stationary part (4), while the magnetic detector or the magnet arrangement is arranged on the movable part (3). Thereby relative movements between the parts (3, 4) result in relative movements between the magnet arrangement and the magnetic detector.

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: The invention concerns a method for controlling a raising drive, the raising process occurring by means of pressure activation of at least one lift cylinder and the lowering process occurring by means of relieving, and a control of the lowering speed occurring by means of a variable flow resistance. In order to achieve a load-independent lowering speed, the flow resistance is determined in dependence of at least one load signal.

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 hydraulic machine has a gear wheel (2) with outwardly extending teeth and a gear ring (4) with inwardly extending teeth formed by rollers each of which is supported in a pocket (8) in the gear ring, and pressurized spaces are formed between the gear wheel and the inwardly extending teeth. To keep the wear of the machine small, each pocket (8) has at least two different radii (R1, R2, Rn) whereby a radius (R2, Rn) at a smaller displacement from the edge (12) of the pocket is larger than a radius (R1) at a larger displacement from the same edge (12) of the pocket (8).

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.