Abstract: An electromagnetic valve actuator and method of control thereof. The electromagnetic valve actuator is for at least one valve of an internal combustion engine, the electromagnetic valve actuator comprising: a rotor; a stator for rotating the rotor; output means for actuating the valve in dependence on rotation of the rotor; mechanical energy storage means arranged to store energy in dependence on rotation of the rotor and release the energy to assist rotation of the rotor and phase varying means for varying a phase between the mechanical energy storage means and the output means.

Abstract: An electromagnetic valve actuator and method of control thereof. The electromagnetic valve actuator is for at least one valve of an internal combustion engine, the electromagnetic valve actuator comprising: a rotor; a stator for rotating the rotor; output means for actuating the valve in dependence on rotation of the rotor; mechanical energy storage means arranged to store energy in dependence on rotation of the rotor and release the energy to assist rotation of the rotor and phase varying means for varying a phase between the mechanical energy storage means and the output means.

Abstract: An electromagnetic valve actuator (100) and method of control thereof. The electromagnetic valve actuator is for at least one valve (300) of an internal combustion engine (40), the electromagnetic valve actuator comprising: a rotor (102); a stator (101) for rotating the rotor; output means (104, 106) for actuating the valve in dependence on rotation of the rotor; mechanical energy storage means (108, 110, 116, 118) arranged to store energy in dependence on rotation of the rotor and release the energy to assist rotation of the rotor; and phase varying means (400) for varying a phase between the mechanical energy storage means and the output means.

Abstract: An electromagnetic valve actuator (100) and method of control thereof. The electromagnetic valve actuator is for at least one valve (300) of an internal combustion engine (40), the electromagnetic valve actuator comprising: a rotor (102); a stator (101) for rotating the rotor; output means (104, 106) for actuating the valve in dependence on rotation of the rotor; mechanical energy storage means (108, 110, 116, 118) arranged to store energy in dependence on rotation of the rotor and release the energy to assist rotation of the rotor; and phase varying means (400) for varying a phase between the mechanical energy storage means and the output means.

Abstract: A linkage for coupling between an actuator and a valve in an engine valve actuation assembly. The linkage provides some compliance in the operation of the linkage to close the valve. The linkage comprises a rocker having a rigid body portion, the body portion including a pivot axis about which it is rotatable, and a link mount for coupling to a valve link arm. The link mount is moveable from a rest position relative to the body portion, and the link mount is urged back towards its rest position when displaced from its rest position relative to the body portion.

Abstract: A desmodromic valve train (20) for an engine (40), comprising a valve actuator (100) arranged to actuate a valve (400) independently of the crank angle of the engine (40), wherein the desmodromic valve train (20) comprises: a load path arrangement comprising an input arranged to receive actuating force from the valve actuator (100), an output arranged to provide the actuating force to the valve (400), and mechanical advantage means arranged such that a first displacement, of the input, causes a second displacement, of the output, wherein the second displacement is a multiple of the first displacement, the multiple being within the range 1.3 to 1.95.

Abstract: A linkage for coupling between an actuator and a valve in an engine valve actuation assembly. The linkage provides some compliance in the operation of the linkage to close the valve. The linkage comprises a rocker (2) having a rigid body portion (4), the body portion including a pivot axis (6) about which it is rotatable, and a link mount (8) for coupling to a valve link arm (40). The link mount is moveable from a rest position relative to the body portion, and the link mount is urged back towards its rest position when displaced from its rest position relative to the body portion.

Abstract: A rotary electromagnetic actuator includes a biasing assembly for applying a torque to its rotor. Such an actuator may be used to operate a poppet valve of an internal combustion engine. The biasing assembly is switchable between (a) a first configuration in which the biasing assembly exerts a torque on the rotor over at least part of the range of rotation of the rotor, wherein the torque exerted varies with the rotational position of the rotor according to a torque profile, and (b) a second configuration in which the biasing assembly exerts substantially no torque on the rotor over the range of the rotor.

Abstract: A rotary electromagnetic actuator includes a biasing assembly for applying a torque to its rotor. Such an actuator may be used to operate a poppet valve of an internal combustion engine. The rotor defines a cam surface and the biasing assembly includes a cam follower in engagement with the cam surface, and the magnitude of the torque exerted on the rotor by the biasing assembly is dependent on the magnitude of the displacement of the cam follower by the cam surface. The cam surface defines at least one detent for receiving the cam follower.

Abstract: A desmodromic valve train (20) for an engine (40), comprising a valve actuator (100) arranged to actuate a valve (400) independently of the crank angle of the engine (40), wherein the desmodromic valve train (20) comprises: a load path arrangement comprising an input arranged to receive actuating force from the valve actuator (100), an output arranged to provide the actuating force to the valve (400), and mechanical advantage means arranged such that a first displacement, of the input, causes a second displacement, of the output, wherein the second displacement is a multiple of the first displacement, the multiple being within the range 1.3 to 1.95.

Abstract: A stator assembly for receiving at least two rotors. The assembly comprises at least two individual stators which are divided into stator segments, with at least one segment being a shared segment which forms part of at least two adjacent individual stators. An engine valve actuation assembly includes a stator assembly comprising at least two individual stators. Each individual stator comprises a peripheral portion extending around the longitudinal axis of the stator, with part of the peripheral portion of each stator forming part of the peripheral portion of an adjacent individual stator. Methods for assembling a stator assembly are also described.