Abstract: A translating actuator acting between two extreme positions defined by mechanical stops is described. Said actuator comprises: an armature mass movable relative to the armature body, a stiff armature spring set such that the natural resting position of the armature mass is close to the centre of travel between the two extreme positions and pair of latches with sufficient holding force that the armature mass can be held at either extreme position against the restoring force of the spring and can be released quickly relative to the natural period of vibration determined by the armature mass on the armature spring.

Abstract: A system comprising two or more thermal stores, a single store for pressurised air and a means of collecting relatively low-grade heat offers the potential for an energy storage system that achieves two desirable aims at the same time: (i) the total exergy that may be released when a given pressurised air store is discharged is maximised and (ii) the ratio between the exergy extracted and the work invested in compressing the air via a multi-stage compressor is also increased by exploiting some source of low-grade heat to augment the thermal content of several thermal stores. The system comprises a compressed air energy storage system which tends, in any one fill-empty cycle of the pressurised air store, to pump heat upwards in temperature from lower-grade stores to the highest-grade thermal store as well as a thermal capture subsystem that can augment the heat content of the lower-grade thermal stores.

Abstract: A system comprising two or more thermal stores, a single store for pressurised air and a means of collecting relatively low-grade heat offers the potential for an energy storage system that achieves two desirable aims at the same time: (i) the total exergy that may be released when a given pressurised air store is discharged is maximised and (ii) the ratio between the exergy extracted and the work invested in compressing the air via a multi-stage compressor is also increased by exploiting some source of low-grade heat to augment the thermal content of several thermal stores. The system comprises a compressed air energy storage system which tends, in any one fill-empty cycle of the pressurised air store, to pump heat upwards in temperature from lower-grade stores to the highest-grade thermal store as well as a thermal capture subsystem that can augment the heat content of the lower-grade thermal stores.

Abstract: An electrical generating system for aircraft with one or more engines includes a plurality of generators associated with the engines so as to produce respective AC outputs. The frequencies of these outputs can differ from each other, as a result of differing engine speeds and/or deliberate design, but they are to be connected to a common bus to avoid redundancy of wiring. One or more converters are present between the generators and the bus for adjusting the output frequency of the generators to provide an AC output voltage at a common bus frequency. The system includes a control system for setting the AC bus frequency in such a way that it can vary with time. The bus frequency may follow the natural frequency of the engine, and only small converters are needed to make the already approximately equal generator frequencies identical, so that they can all feed the common bus.

Abstract: Described herein is a torque-limiting coupling provided for connecting coaxial, first and second rotating shafts. The coupling includes a first connecting part on an end of the first shaft and a second connecting part on an end of the second shaft. An interconnector joins to the first connecting part at a first engagement formation, and joins to the second connecting part at a second engagement formation. The first engagement formation threadingly joins the interconnector to the first connecting part. The second engagement formation can resist rotational movement of the interconnector relative to the second connecting part but allows movement of the interconnector in the axial direction of the shafts. When a torque transmitted by the shafts exceeds a predetermined value, the interconnector rotates relative to the first connecting part at the threaded engagement formation.

Abstract: The present invention relates to a bearing assembly (1) for a rotatable shaft (2). The bearing assembly comprises a bearing housing (10); a bearing (20) located within the bearing housing (10) and arranged in use to receive a rotatable shaft (2); and an elongate member (14) that couples the bearing (20) to the bearing housing (10) for damping vibrations of the rotatable shaft (2). The elongate member (14) comprises a piezoelectric element (40) which may be actuated so as to exert a force on the elongate member. This arrangement allows the bearing assembly to damp vibrations of the rotatable shaft.

Abstract: The present invention relates to a bearing assembly (1) for a rotatable shaft (2). The bearing assembly comprises a bearing housing (10); a bearing (20) located within the bearing housing (10) and arranged in use to receive a rotatable shaft (2); and a damper (14) that couples the bearing (20) to the bearing housing (10) for damping vibrations of the rotatable shaft (2). The damper (14) comprises a shape memory alloy (40). This arrangement allows the bearing assembly to damp vibrations of the rotatable shaft.

Abstract: Described herein is a torque-limiting coupling provided for connecting coaxial, first and second rotating shafts. The coupling includes a first connecting part on an end of the first shaft and a second connecting part on an end of the second shaft. An interconnector joins to the first connecting part at a first engagement formation, and joins to the second connecting part at a second engagement formation. The first engagement formation threadingly joins the interconnector to the first connecting part. The second engagement formation can resist rotational movement of the interconnector relative to the second connecting part but allows movement of the interconnector in the axial direction of the shafts. When a torque transmitted by the shafts exceeds a predetermined value, the interconnector rotates relative to the first connecting part at the threaded engagement formation.

Abstract: An electrical generating system for aircraft with one or more engines includes a plurality of generators associated with the engines so as to produce respective AC outputs. The frequencies of these outputs can differ from each other, as a result of differing engine speeds and/or deliberate design, but they are to be connected to a common bus to avoid redundancy of wiring. One or more converters are present between the generators and the bus for adjusting the output frequency of the generators to provide an AC output voltage at a common bus frequency. The system includes a control system for setting the AC bus frequency in such a way that it can vary with time. The bus frequency may follow the natural frequency of the engine, and only small converters are needed to make the already approximately equal generator frequencies identical, so that they can all feed the common bus.

Abstract: The present invention relates to a bearing assembly (1) for a rotatable shaft (2). The bearing assembly comprises a bearing housing (10); a bearing (20) located within the bearing housing (10) and arranged in use to receive a rotatable shaft (2); and an elongate member (14) that couples the bearing (20) to the bearing housing (10) for damping vibrations of the rotatable shaft (2). The elongate member (14) comprises a piezoelectric element (40) which may be actuated so as to exert a force on the elongate member. This arrangement allows the bearing assembly to damp vibrations of the rotatable shaft.

Abstract: The present invention relates to a bearing assembly (1) for a rotatable shaft (2). The bearing assembly comprises a bearing housing (10); a bearing (20) located within the bearing housing (10) and arranged in use to receive a rotatable shaft (2); and a damper (14) that couples the bearing (20) to the bearing housing (10) for damping vibrations of the rotatable shaft (2). The damper (14) comprises a shape memory alloy (40). This arrangement allows the bearing assembly to damp vibrations of the rotatable shaft.

Abstract: A blade arrangement 31 includes an array of radially extending blades 20, which may for example comprise a fan of a gas turbine engine for an aircraft. The blades 20 are mounted for rotation about a central axis X-X. The blade arrangement 31 further includes a damping arrangement 32 comprising means 34 for inducing an axi-symmetric magnetic field whose axis of symmetry coincides with the central axis X-X of rotation of the blades 20. The damping arrangement 32 is configured such that when the magnetic field is induced, any movement of the blade 20 other than pure rotation about the central axis results in the magnetic field causing a force to be exerted on the blade 20, the force resisting such movement. The damping arrangement may be provided with means for inducing the magnetic field only when there is an increased likelihood of vibration of the blades, for example when a foreign body has entered the air intake of the engine.

Abstract: A magnetic bearing has two bearing members each of which carries a set of bearing elements. The bearing elements carried by one member are interleaved with the bearing elements carried by the other member to define three or more substantially parallel interleaf gaps between successive elements, so that bearing forces can be developed as a result of magnetic shear stresses acting across those gaps. The magnetic bearing achieves its bearing forces as the sum of force contributions from a number of parallel (or nearly-parallel) airgaps and each of these individual airgap force contributions comes about as the integration of magnetic shear stress over the airgap area brought about by causing lines of magnetic flux to cross the airgap at an angle to the normal.

Abstract: Correcting unbalance with regard to rotors (11, 101) and shafts is important in order to improve performance of those rotors (11, 101) or shafts within a practical machine or engine. Previously, result orientated iterative balancing of the rotor or shaft has been achieved in which mass has been added or possibly intrusive and distorted adjustments in drag and stiffness presented through bearings or alteration of the rotor (11, 101) itself have been utilised to improve rotor balance performance. In the present invention, a dynamic bearing 13 is utilised in order to provide force components with some components in phase with rotor deflection in order to simulate negative stiffness and/or some force components in phase with rotor velocity in order to simulate negative drag upon the rotor (11, 101). In such circumstances, a more accurate determination of rotor unbalance is achieved to enable known techniques of perturbed boundary condition analysis for balance correction to be implemented more accurately.

Abstract: A blade arrangement 31 includes an array of radially extending blades 20, which may for example comprise a fan of a gas turbine engine for an aircraft. The blades 20 are mounted for rotation about a central axis X-X. The blade arrangement 31 further includes a damping arrangement 32 comprising means 34 for inducing an axi-symmetric magnetic field whose axis of symmetry coincides with the central axis X-X of rotation of the blades 20. The damping arrangement 32 is configured such that when the magnetic field is induced, any movement of the blade 20 other than pure rotation about the central axis results in the magnetic field causing a force to be exerted on the blade 20, the force resisting such movement. The damping arrangement may be provided with means for inducing the magnetic field only when there is an increased likelihood of vibration of the blades, for example when a foreign body has entered the air intake of the engine.

Abstract: A Method and Machine for Shaft Imbalance Determination Correcting unbalance with regard to rotors (11, 101) and shafts is important in order to improve performance of those rotors (11, 101) or shafts within a practical machine or engine. Previously, result orientated iterative balancing of the rotor or shaft has been achieved in which mass has been added or possibly intrusive and distorted adjustments in drag and stiffness presented through bearings or alteration of the rotor (11, 101) itself have been utilised to improve rotor balance performance. In the present invention, a dynamic bearing 13 is utilised in order to provide force components with some components in phase with rotor deflection in order to simulate negative stiffness and/or some force components in phase with rotor velocity in order to simulate negative drag upon the rotor (11, 101).

Abstract: This invention is a rotating electrical machine comprising two major components capable of relative rotation about a common axis and separated by an air gap in which magnetic fields linking the two main components through the air gap act both to exert torque and lateral forces. A set of windings is present on at least one of these components and this set of winding is used to generate a distribution of flux having two parts: the first part serving primarily to case torque and the second part serving to cause a net lateral force between the two main components. This machine uses the physical connection of the coils within the phases of the machine such that separate sources can be used for supplying currents for generating torque and lateral forces independently. The voltage and current ratings of the supply used for generating the lateral forces can both be substantially lower than the corresponding ratings of the supply used for generating the torque.