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 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 valve control system is provided for an internal combustion engine, the engine having at least one cylinder with at least one set of at least two valves. All the valves in the set are either inlet valves or exhaust valves, and the system is configured to selectively operate the set of valves in a single valve mode of operation during which only one valve of the set is open at any time.

Abstract: An assembly for coupling a valve stem to an actuating member of an actuator in a desmodromic valve actuation mechanism comprises a spherical bearing having two portions each of which defines a respective bearing surface which is complementary to the bearing surface defined by the other portion, at least one of the surfaces being part spherical, one of the portions being arranged to be coupled to the actuating member and the other portion being arranged to be coupled to the valve stem; and a resilient arrangement which exerts a biasing force on one of the bearing portions and provides resilience in the coupling provided by the assembly between the valve stem and actuating member.

Abstract: A rotary electromagnetic actuator is provided which is suitable for opening and closing a valve for example. The actuator comprises a rotor, a stator, and a biasing arrangement for applying a torque to the rotor during at least part of its rotation. A plurality of stable rest positions for the rotor are defined by forces acting on the rotor and the actuator is controllable to move the rotor from one stable rest position to another. The torque applied by the biasing arrangement varies with the rotational position of the rotor such that at a primary rest position and at least a second rest position, it is sufficiently low to enable selection of those positions, and then it increases beyond the second rest position.

Abstract: A valve control system for an internal combustion engine, the engine having at least one cylinder with at least one intake or exhaust valve and a piston and the valve being operable independently of the rotation of the engine crankshaft. The system is configured to generate a control signal that controls a preconditioning actuation cycle of an actuator prior to a first combustion cycle of the engine, receive a feedback signal relating to an operating condition of the actuator during the preconditioning actuation cycle, and generate a modified control signal that controls a combustion actuation cycle of the actuator, modified with reference to the feedback signal. This recalibration of the valve control signals allows the current operating conditions of the valve train to be taken into account before the first combustion cycle of the engine.

Abstract: A lock assembly for use in automotive and industrial transmission systems comprises: an actuator (2) having an impeller (6) movable between two rest positions by energizing the actuator, wherein the impeller is retained in each of the two rest positions by passive magnetic forces generated by the actuator; a locking arrangement (10, 22; 42, 52; 62, 64; 70, 74; 80, 96) switchable between a first configuration in which rotation of a shaft is unimpeded by the locking arrangement and a second configuration in which rotation of said shaft is blocked by the locking arrangement; and a linkage (14, 16; 44, 46, 61, 88) between the impeller and the locking arrangement, wherein the assembly is arranged such that in one of the impeller rest positions, the locking arrangement is in its first configuration and said shaft is freely rotatable, and in the other of the impeller rest positions, the locking arrangement is urged towards and into its second configuration.

Abstract: A rotary electromagnetic actuator is provided which is suitable for opening and closing a valve for example. The actuator comprises a rotor (10), a stator (16), and a biasing arrangement (20, 100, 102, 104, 106) for applying a torque to the rotor during at least part of its rotation. A plurality of stable rest positions (200; 316, 318; 400) for the rotor are defined by forces acting on the rotor and the actuator is controllable to move the rotor from one stable rest position to another. The torque applied by the biasing arrangement varies with the rotational position of the rotor such that at a primary rest position and at least a second rest position, it is sufficiently low to enable selection of those positions, and then it increases beyond the second rest position.