Abstract: A hydraulic machine in which the volume of working fluid displaced by each cylinder is selectable on each cycle of working chamber volume by active control of one or more electronic valves has a controller configured to select specified groups of cylinders to repetitively carry out active cycles until a change in selection is made. The groups are selected to reduce torque ripple and/or bearing side load. The cam profile may be varied to further reduce torque ripple.

Abstract: An object of the invention is to provide a wind turbine generator or a tidal current generator which is equipped with a hydraulic transmission and achieves a superior power generation efficiency, and a operation method thereof. The wind turbine generator 1 comprises a hydraulic pump 12 of a variable displacement type which is rotated by the main shaft 8, a hydraulic motor 14 of a variable displacement type which is connected to the generator 20, and a high pressure oil line 16 and a low pressure oil line 18 which are arranged between the hydraulic pump 12 and the hydraulic motor 14. The pump controller 32 obtains a target torque of the hydraulic pump 12 at which a power coefficient becomes maximum, and then sets a displacement Dp of the hydraulic pump 12 based on the target torque and the pressure in the high pressure oil line 16.

Abstract: A power generating apparatus includes a rotating shaft, a hydraulic pump driven by the rotating shaft, a hydraulic motor driven by pressurized oil supplied from the hydraulic pump, and a generator coupled to the hydraulic motor. Each of the hydraulic pump and motor includes working chambers each defined by a cylinder and a piston, a high pressure manifold and a low pressure manifold. Each of the high and low pressure manifolds includes branch channels connected to the working chambers and a merging channel connected to a high or low pressure oil line. The branch channels are equipped with high or low pressures valves, joined together and merged into the merging channel.

Abstract: A wind turbine generator, or other energy extraction device, has a hydraulic circuit comprising a hydraulic pump driven by a rotating shaft and a hydraulic motor driving an electricity generator. When the electricity generator is switched off, it executes one or more pumping cycles to pressurise the high pressure manifold and therefore recover angular kinetic energy from the electricity generator rotor which can later be used to reaccelerate the electricity generator rotor to the correct operating speed for an electricity grid. Overall energy efficiency is increased and the minimum operating high pressure manifold pressure may be reduced as a result.

Abstract: The present invention provides a hydraulic pump for use in driving a load with a control modulation system which modulates a primary control signal in order to accommodate variations in secondary changeable parameters which require control at a higher frequency or have a lower latency.

Abstract: An object of the invention is to provide a wind turbine generator or a tidal current generator which is equipped with a hydraulic transmission and achieves a superior power generation efficiency, and a operation method thereof. The wind turbine generator 1 comprises a hydraulic pump 12 of a variable displacement type which is rotated by the main shaft 8, a hydraulic motor 14 of a variable displacement type which is connected to the generator 20, and a high pressure oil line 16 and a low pressure oil line 18 which are arranged between the hydraulic pump 12 and the hydraulic motor 14. The pump controller 32 obtains a target torque of the hydraulic pump 12 at which a power coefficient becomes maximum, and then sets a displacement Dp of the hydraulic pump 12 based on the target torque and the pressure in the high pressure oil line 16.

Abstract: An electro-magnetic mechanism comprises a spring-operated rod (1) having a recess (1a) and a latching member (2) engageable in the recess to block motion of the rod. A release member (4) retains the latching member engaged in the recess (1a) in a first position of the release member and allows the latching member to be disengaged from the recess in a second position of the release member (4). A magnet (5) retains the release member in the first position and the mechanism includes an element such as a spring (7) for urging the release member (4) to the second position. A coil (8) is arranged to demagnetize the magnet (5) at least such that the release member moves to the second position, the latching member (2) is disengaged from the recess (1a) and the rod (1) moves axially by spring force.

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: An electro-magnetic mechanism comprises a spring-operated rod (1) having a recess (1a) and a latching member (2) engageable in the recess to block motion of the rod. A release member (4) retains the latching member engaged in the recess (1a) in a first position of the release member and allows the latching member to be disengaged from the recess in a second position of the release member (4). A magnet (5) retains the release member in the first position and the mechanism includes means such as a spring (7) for urging the release member (4) to the second position. A coil (8) is arranged to demagnetise the magnet (5) at least such that the release member moves to the second position, the latching member (2) is disengaged from the recess (1a) and the rod (1) moves axially by spring force.

Abstract: A fluid-working machine has working chambers (4), each of which is connected to a fluid commutating means (2) which alternately connects the working chamber to either of two fluid manifolds (A, B). An electronically controlled valve (1) is inserted into the flow path between each chamber (4) and the commutating means. This valve is commanded by a controller (6) receiving an input signal of the phase angle of the shaft (5) of the machine or at least one electronic pulse per revolution which informs the controller that the shaft is passing a known phase angle. The valve (1) allows overriding of fixed mechanical commutation by closing the valve cyclically, synchronised with the angular position of the shaft (5). Thus the controller (6) is able to vary the time-averaged fluid flow into or out of the machine by varying the proportion of chambers (4) which are isolated from or connected to the mechanical commutating means (2), to control the torque, speed, and/or fluid flow into and out of the machine.

Abstract: An electronic traction control system for a vehicle having multiple hydraulic driven wheels includes a plurality of digital displacement pumps, a plurality of drive systems having counterbalance valves and motors used to drive wheels, and electronic flow control valves used in association with each drive assembly. Additionally the system has a steering mechanism that is electrically connected to a digital sensor and a proportional sensor that sends signals to a system controller that operates the functioning of the digital displacement hydraulic pumps.

Abstract: A fluid-working machine has a plurality of working chambers, e.g. cylinders (11), of cyclically changing volume, a high-pressure fluid manifold (14) and a low-pressure fluid manifold (16), at least one valve (13, 15) linking each working chamber to each manifold, and electronic sequencing means (20) for operating said valves in timed relationship with the changing volume of each chamber (11), wherein the electronic sequencing means is arranged to operate the valves of each chamber in one of an idling mode, a partial mode in which only part of the usable volume of the chamber is used, and a full mode in which all of the usable volume of the chamber (11) is used, and the electronic sequencing means (20) is arranged to select the mode of each chamber on successive cycles so as to infinitely vary the time averaged effective flow rate of fluid through the machine.

Abstract: A valve assembly (1) operable to allow or prevent the flow of fluid to or from a working chamber of a fluid-operated machine, comprising radially spaced apart inner and outer annular valve seats (8, 15) defining an annular passage therebetween, a valve member comprising a sealing ring (21), and means (3, 7, 26, 25) for moving the valve member axially between a first position in which the sealing ring (21) is in seating engagement with the annular valve seats to close the annular passage to fluid flow therethrough and a second position in which the sealing ring (21) is spaced from the annular valve seats (8, 15) so that the annular passage is open to fluid flow therethrough. The valve assembly further comprises axially spaced apart first and second valve guide means (6) for guiding the valve member during axial movement between its first and second positions.