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: 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 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: 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: 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: 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 provides a fluid controller for controlling a machine, e.g. for steering a vehicle. The controller comprises a housing defining an inlet port connected to the source and an outlet port connected to the pressure operated device. The flow rate is controlled by movement of a valve member within the housing, and a processor provides a reference which is indicative of a desired position of the valve member relative to the housing. The fluid controller comprises a fault detection system based on an observer. The observer calculates a theoretically correct position of the valve member relative to the housing for a given reference, and compares this position to an obtained position of the valve member relative to the housing. The difference between the positions is compared with a threshold value. In order to dynamically change the sensitivity of the system, the threshold value is scaled based on a gradient of the reference.

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: The invention concerns a fluid rotary machine (1) with a housing (2), a shaft (3) led out of the housing (2) and a sensor arrangement (10) comprising a transmitter (12) in active connection with the shaft (3), and a receiver (15). It is endeavoured to arrange the sensor arrangement in an advantageous manner on the fluid rotary machine. For this purpose, the sensor arrangement (10) comprises an accommodation area, in which the transmitter (12) is arranged, the accommodation area being in fluid connection with the inside of the housing (2) and sealed towards the outside, and the receiver (15) is arranged outside the housing (2) and the accommodation area.

Abstract: The invention concerns a fluid rotary machine (1) with a housing (2), a shaft (3) projecting from the housing (2), and being rotatable around an axis (4) and forming part of a movement chain, and a sensor arrangement (10) comprising a transmitter (12) and a receiver (15). It is endeavoured to find a simple solution for detecting the rotation of the shaft with a relatively high accuracy. For this purpose, a channel (21) is provided in the movement chain, and the transmitter (12) is connected to a transfer element (19) transferring a torque that is led through said channel (21) to a section of the movement chain that is farther away from the transmitter (12) than a transmitter-side end of the movement chain.

Abstract: A fluid working machine comprises a controller (12) and a working chamber (2) of cyclically varying volume. The working, chamber has both an electronically controllable primary low pressure valve (14) and a secondary low pressure port (22) associated therewith, each of which is openable and closable in phased relation to cycles of working chamber volume to bring the working chamber into fluid communication with a low pressure manifold (16, 26). At least the primary low pressure valve is under the active control of the controller to enable the controller to determine the net displacement of fluid by the working chamber on a cycle by cycle basis. The primary low pressure valve and the secondary low pressure port are openable concurrently during a portion of at least some cycles of working chamber volume to enable fluid to flow into or out of the working chamber concurrently through both the primary low pressure valve and the secondary low pressure port.

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: The invention provides a method of calibrating a steering system for a vehicle, e.g. an off-highway machinery, to allow automatic steering based on input from a position or tracking system, e.g. based on a Global Positioning System (GPS). At least two records, each comprising a position value and a curvature value are established. The position value represents a position of the steered element, e.g. a position of a steered wheel of the vehicle, and the curvature value could e.g. be expressed as a radius of a curve followed by the vehicle with that position of the steered element. The curvature value is determined by the positioning system during movement of the vehicle. Due to the records, it is easy to calibrate or recalibrate the system and the invention is therefore applicable e.g. in connection with manufacturing of vehicles in small batch numbers, e.g. for one of a kind production or for retrofitting of steering components to existing vehicles.

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 concerns a hydraulic machine with a set of teeth, having a toothed ring with an inner toothing and a gear wheel with an outer toothing, the gear wheel rotating and orbiting in the toothed ring, the inner toothing and the outer toothing touching each other in contact areas, thus separating pressure chambers, and with a valve arrangement controlling a connection between a connection arrangement having a high pressure connection and a low pressure connection, and the pressure chambers. It is endeavoured to achieve a stable operation, particularly with low speeds. For this purpose, each contact area is provided with an opening, which, at the time when a pressure chamber reaches an extreme value of its volume, produces a short-circuiting with the neighbouring pressure chamber.