Abstract: The invention concerns a hydraulic steering arrangement (1) with a supply connection arrangement (P, T), a working connection arrangement (A, B) connectable to a steering motor (5), a steering unit (6) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a steering valve (14) whose outlet is connected to the working connection arrangement (A, B). It is endeavored to keep the load of such a steering arrangement small. For this purpose, the steering unit (6) is made as an open-center steering unit, an inlet (20) of the steering valve (14) being connected to a pressure supply arrangement (22) that can be activated by an activation of the steering valve (14).

Abstract: A hydraulic actuator for a hydraulic servomotor (4) is disclosed. The hydraulic servomotor (4) is of a kind having at least one defined end position, and has a first chamber (5) and a second chamber (6) associated therewith. The actuator is connected to a fluid source (2) and a fluid drain (3). The actuator comprises a first valve (7) fluidly connected between the fluid source (2) and the first chamber (5), a second valve (8) fluidly connected between the first chamber (5) and the fluid drain (3), and a third valve (9) fluidly connected between the fluid source (2) and the second chamber (6). The actuator further comprises a flow channel (10, 17), preferably comprising a flow restrictor (12, 18), in fluid communication with the second chamber (6). The valves (7, 8, 9) are such that, in the case of a power cut off, they will prevent a fluid flow out of the first chamber (5), and a fluid flow out of the second chamber (6) takes place via the flow channel (10, 17).

Abstract: The invention provides a fluid controller, e.g. for a hydrostatic power steering. The controller comprises a cylindrical valve member cooperating with a housing to define at least one fluid path from a pressure source to a steering cylinder. The valve member is rotatable in the housing and comprises a sleeve and a spool, wherein the spool is rotatable within the sleeve. The fluid flow is metered by a flow meter, and the valve member comprises a plurality of meter ports communicating the fluid between the valve member and the flow meter. To obtain less friction between the sleeve and the housing and between the sleeve and the spool, the meter ports are grouped in two groups in which groups the ports are in mutually fluid communication.

Abstract: The invention concerns a hydraulic steering with a steering initiator, a steering unit with feedback properties, which can be activated by the steering initiator, the steering unit having a supply connection arrangement with a pressure connection (P) and a tank connection (T) and a working connection arrangement with two working connections (L, R), an auxiliary-force operated steering valve, which is located in parallel with the steering unit between the supply connection arrangement (P, T) and the working connection arrangement (L, R), and a feedback suppressing device, which is active, when the steering valve is active. It is endeavored to find a simple manner of ensuring the priority of the steering initiator over the steering valve. For this purpose, the steering initiator interacts with an activation sensor, which deactivates the feedback suppressing device on an activation of the steering initiator.

Abstract: The invention provides a steering system comprising a controlled element which is movable in a neutral area comprising a neutral position and in areas on opposite sides of the neutral area based on a steering input and a handle for requesting a desired position for the controlled element. The handle is movable between set-points in a centre zone comprising a centre set-point and set-points on opposite sides of the centre zone. Furthermore, a steering unit is arranged to receive set-points from the handle, to determine a corresponding controlled position of the controlled element, and to move the controlled element to said controlled position. In order to prevent or reduce jerks, the steering unit is adapted to vary a speed by which the controlled element is moved to the controlled position. The speed is variable in dependence of the received set-point.

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: The invention concerns a hydraulic steering (1) with a supply connection arrangement (P, T), a steering motor (2) and a steering unit (3) between the supply connection arrangement and the steering motor (2), the steering unit (3) having a directional section (4) and a measuring section (5), a steering valve (9) being arranged in parallel to the steering unit (3). With such a steering, it is endeavoured to achieve the best possible safety. For this purpose, it is ensured that for each steering direction the directional section (4) comprises a first outlet (A1L, A1R), which is connected to the steering motor (2) by means of a first pipe (23, 24), and a second outlet (A2L, A2R), which is connected to the steering motor (2) by means of a second pipe (25, 26), the first outlet (A1L, A1R) being, in the neutral position of the directional section (4), connected to the measuring section (5), and the first pipe (23, 24) being interruptible by means of a valve arrangement (27, 27a).

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: 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 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) having at least two working connections (A, B), a check valve (5, 6) being allocated to each working connection (A, B), and a pressure relief valve (7, 8) being allocated to each check valve (5, 6), each pressure relief valve (7, 8) being connected to a control pressure passage (17, 18). The valve arrangement shall ensure a reliable, pressure-less lowering, also in connection with single-actuated consumers, and further enable a pressure-less float position. For this purpose, the check valves (5, 6) can be opened by means of tappets (20, 21), whose sides facing away from the check valves (5, 6) are ending in a pressure chamber (22), which is connected to the control pressure passage (17, 18) of one of the pressure relief valves (7, 8).

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 provides a method and a system for moving an element, e.g. a rudder of a ship or a wheel of a vehicle. The element is moved by a hydraulic fluid. According to the invention, an operator indicates a desired movement, and in accordance with the desired movement, at fluid is provided from at least three fluid providers each providing a share of the fluid in parallel streams and only considering the desired movement not the shares provided by the other fluid providers. The invention allows continuation of a steering task even if one fluid provider is disabled, and the invention allows the continuation even without having to notice that one provider is disabled. Accordingly, the invention provides an improvement and simplification relative to the known hydraulic steering systems.

Abstract: The invention concerns a hydraulic machine (1) with an externally toothed gear wheel (2) and an internally toothed ring (3), which is made of a sintered material or of a ceramic material. It is endeavored to provide good operation behaviour at low costs. For this purpose, the toothed ring (3) is provided with a sealing element (7) in the area of its outer circumference.

Abstract: The invention provides a steering system e.g. for a vehicle. The system comprises a system-pump, a steering actuator, a rotary valve, a rotary meter, and a motor. The system-pump is arranged to provide a flow of a fluid to the steering actuator via the rotary valve and via the rotary meter, and the motor is arranged to provide rotation of the rotary valve and the rotary meter. To handle an emergency situation if the system-pump fails, the motor is dimensioned to operate the rotary meter as a fail-operational pump for pumping a flow of the fluid to the steering actuator if the system-pump fails.

Abstract: The invention concerns a hydraulic valve arrangement (1) with at least two valve modules (2-6), each having a supply channel arrangement with a high-pressure channel (9) and a low-pressure channel (15), a working connection arrangement with at least one working connection (A, B), one directional valve arrangement (16) between the supply channel arrangement (9, 15) and the working connection arrangement (A, B) and a compensation arrangement (19), which is acted upon by a pressure in a load-sensing arrangement. It is endeavoured to increase the number of control possibilities. For this purpose, the load-sensing arrangement of at least one valve module (2-6) has a pressure influencing arrangement (25-29) that differs from a pressure influencing arrangement (25-29) of a load sensing arrangement of another valve module (2-6).

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: The invention concerns a hydraulic valve arrangement (1) with several valve modules (2-6), each having a supply channel arrangement with a high-pressure channel (7) and a low-pressure channel (8), a working connection arrangement with at least one working connection (A, B), a directional valve arrangement (15, 16) between the supply channel arrangement and the working connection arrangement and a compensation arrangement (19, 28). It is endeavoured to improve the control possibilities. For this purpose, it is provided that in at least one valve module (3, 5) the compensation arrangement is a pre-compensation arrangement (19) and in at least one other valve module (4, 6) the compensation arrangement is a post-compensation arrangement (28).

Abstract: A valve assembly (2) forming a bridge circuit and a hydraulic actuator comprising at least one valve assembly (2) are disclosed. The valve assembly (2) is fluidly connectable between a fluid source (3) and a fluid drain (4). The valve assembly (2) comprises a first valve (8) fluidly connected between the fluid source (3) and a first diagonal point (12) of the bridge circuit, a second valve (9) fluidly connected between the fluid source (3) and a second diagonal point (13) of the bridge circuit, a third valve (10) fluidly connected between the first diagonal point (12) and the fluid drain (4), and a fourth valve (11) fluidly connected between the second diagonal point (13) and the fluid drain (4). The valves (8, 9, 10, 11) are such that in the case of a power cut off, flows of fluid away from the diagonal points (12, 13) are prevented.