Abstract: An electromagnetic actuator and a valve in combination with an electromagnetic actuator are described. The actuator comprises an armature comprising a permanent magnet, two coils and two coil cores, each of which extends within a respective coil. The armature is moveable relative to the coils between first and second stable rest positions by passing a current through at least one of the coils. In each rest position, the armature is closer to one of the coil cores than the other of the coil cores and is spaced by a gap from the closer coil core. The actuator may be combined with a pinch valve for controlling the flow of a fluid through tubing or an inline valve.

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: An air braking unit for use in an air braking system. The air braking unit is arranged to be positioned, in use, at a vehicle wheel, and comprises an inlet for receiving, in use, compressed air from a central source. At least one first valve is arranged to selectively allow compressed air from the inlet to enter a wheel brake chamber in use. At least one second valve is arranged to selectively allow air from the brake chamber to be released via an outlet to the atmosphere in use and control means controls the first and second valves to operate to selectively control the air pressure in the brake chamber in use.

Abstract: An electromagnetic valve comprises a yoke, a magnet having pole pieces defining a gap, a flexure assembly having one end attached to the yoke such that part of the flexure assembly extends into the gap, and a mechanism configured to polarize the magnetizable portion so that the extending part of the flexure assembly is attracted towards a pole piece by a magnetic force, thereby defining a valve state. The flexure assembly has at least one resilient portion and at least one magnetizable portion, wherein the extending part of the flexure assembly is movable between the pole pieces through an intermediate position towards which it is resiliently biased such that a resilient mechanical force is generated by deflecting the resilient portion from an undeflected position. The magnetizable portion and the resilient portion are configured such that the magnetic force defining the valve state is greater than the resilient mechanical force.

Abstract: An electromagnetic valve comprises a yoke, a magnet having pole pieces defining a gap, a flexure assembly having one end attached to the yoke such that part of the flexure assembly extends into the gap, and a mechanism configured to polarize the magnetizable portion so that the extending part of the flexure assembly is attracted towards a pole piece by a magnetic force, thereby defining a valve state. The flexure assembly has at least one resilient portion and at least one magnetizable portion, wherein the extending part of the flexure assembly is movable between the pole pieces through an intermediate position towards which it is resiliently biased such that a resilient mechanical force is generated by deflecting the resilient portion from an undeflected position. The magnetizable portion and the resilient portion are configured such that the magnetic force defining the valve state is greater than the resilient mechanical force.

Abstract: An electromagnetic valve comprises a yoke, a magnet having pole pieces defining a gap, a flexure assembly having one end attached to the yoke such that part of the flexure assembly extends into the gap, and a mechanism configured to polarize the magnetizable portion so that the extending part of the flexure assembly is attracted towards a pole piece by a magnetic force, thereby defining a valve state. The flexure assembly has at least one resilient portion and at least one magnetizable portion, wherein the extending part of the flexure assembly is movable between the pole pieces through an intermediate position towards which it is resiliently biased such that a resilient mechanical force is generated by deflecting the resilient portion from an undeflected position. The magnetizable portion and the resilient portion are configured such that the magnetic force defining the valve state is greater than the resilient mechanical force.

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 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.

Abstract: An electromagnetically operated switching device comprises an armature (82,102) having a magnetisable and moveable portion (82b,102b) for displacement between two stable rest positions. Two pole pieces (60,62) are disposed on opposite sides of the armature. The pole pieces form poles of opposing polarity adjacent to the armature, and the armature is magnetically attracted to a respective pole piece in each of its stable rest positions. A coil (54) is arranged to polarise the moveable portion of the armature when the coil is energised, such that the moveable portion of the armature is displaced from one stable rest position to the other by energising the coil so as to polarise the portion to the opposite polarity to the adjacent pole piece. Each pole piece (60,62) comprises a permanent magnet (68,70) with the permanent magnets disposed on opposite sides of the moveable portion (82b,102b) of the armature (82,102). The device may be configured to control the flow of fluids.

Abstract: Gas injection control devices are provided, particularly for deployment in a well-bore to control injection of a gas into a tube or pipe to lift a liquid up the tube, such as crude oil for example. A gas control device is described which comprises a housing, and at least two control valve arrangements within the housing. Each arrangement has an inlet for receiving gas from a pressurized supply, an outlet for supplying pressurized gas for injection into the tube, an inlet valve in a fluid path between the inlet and outlet, and an actuator associated with the inlet valve. Each actuator is independently controllable to switch the respective inlet valve between its open and closed configurations. This allows the gas injection to be switched on and off, and facilitates control of the injection gas flow rate.

Abstract: A multistable electromagnetic actuator is provided which addresses a need for a more robust, reliable and energy efficient actuation device. It comprises an armature (10) having a permanent magnet (8), wherein the armature is movable between first and second stable positions, and two electric coils (14a,14b) disposed on opposing sides of the armature along its direction of movement, with their axes substantially aligned with said direction. A magnetic flux container (2) substantially surrounds the armature and the coils to contain magnetic flux generated thereby and to shield its interior from external magnetic flux. In each stable position magnetic flux generated by the permanent magnet (8) extends around a magnetic circuit path including the container so as to retain the armature in its stable position. Energising the coils (14a,14b) causes the armature (10) to move from one stable position to the other. It is suitable for a broad range of applications, including fluid flow control for example.

Abstract: An electromagnetically operated switching device comprises an armature (82,102) having a magnetisable and moveable portion (82b,102b) for displacement between two stable rest positions. Two pole pieces (60,62) are disposed on opposite sides of the armature. The pole pieces form poles of opposing polarity adjacent to the armature, and the armature is magnetically attracted to a respective pole piece in each of its stable rest positions. A coil (54) is arranged to polarise the moveable portion of the armature when the coil is energised, such that the moveable portion of the armature is displaced from one stable rest position to the other by energising the coil so as to polarise the portion to the opposite polarity to the adjacent pole piece. Each pole piece (60,62) comprises a permanent magnet (68,70) with the permanent magnets disposed on opposite sides of the moveable portion (82b,102b) of the armature (82,102). The device may be configured to control the flow of fluids.

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.

Abstract: A multistable electromagnetic actuator is provided which addresses a need for a more robust, reliable and energy efficient actuation device. It comprises an armature (10) having a permanent magnet (8), wherein the armature is movable between first and second stable positions, and two electric coils (14a,14b) disposed on opposing sides of the armature along its direction of movement, with their axes substantially aligned with said direction. A magnetic flux container (2) substantially surrounds the armature and the coils to contain magnetic flux generated thereby and to shield its interior from external magnetic flux. In each stable position magnetic flux generated by the permanent magnet (8) extends around a magnetic circuit path including the container so as to retain the armature in its stable position. Energising the coils (14a,14b) causes the armature (10) to move from one stable position to the other. It is suitable for a broad range of applications, including fluid flow control for example.

Abstract: Actuators and valve-actuator combinations are disclosed which require low power for actuation, and which are particularly suitable for use to control a valve associated with a pipeline. Such an actuator (20) comprises a thrust member (26) moveable between two end of travel positions, an annular rotor having magnetic poles, an annular magnetisable stator having at least one winding and poles with which the rotor poles are aligned in each of a plurality of rotational positions of the rotor relative to the stator, and a drive connection between the rotor and the thrust member which is adapted to convert rotational movement of the rotor into linear movement of the thrust member. The actuator is able to hold its position using minimal energy, and may be located within or around an associated pipe.

Abstract: Gas injection control devices are provided, particularly for deployment in a well-bore to control injection of a gas into a tube or pipe to lift a liquid up the tube, such as crude oil for example. A gas control device is described which comprises a housing, and at least two control valve arrangements within the housing. Each arrangement has an inlet for receiving gas from a pressurized supply, an outlet for supplying pressurized gas for injection into the tube, an inlet valve in a fluid path between the inlet and outlet, and an actuator associated with the inlet valve. Each actuator is independently controllable to switch the respective inlet valve between its open and closed configurations. This allows the gas injection to be switched on and off, and facilitates control of the injection gas flow rate.

Abstract: An air braking unit for use in an air braking system. The air braking unit is arranged to be positioned, in use, at a vehicle wheel, and comprises an inlet for receiving, in use, compressed air from a central source. At least one first valve is arranged to selectively allow compressed air from the inlet to enter a wheel brake chamber in use. At least one second valve is arranged to selectively allow air from the brake chamber to be released via an outlet to the atmosphere in use and control means controls the first and second valves to operate to selectively control the air pressure in the brake chamber in use.

Abstract: An electromagnetic actuator is described in which a rotor comprising permanent magnet means is rotatable in a stator which is magnetisable by causing an electric current to flow through at least one winding associated with the stator. The rotor has at least two stable rest positions, each defined by spring and/or magnetic forces acting on the rotor. Spring means stores energy during part of the movement of the rotor and provides kinetic energy for accelerating the rotor during subsequent movement thereof away from rest in one position towards another. A magnetic torque is exerted on the rotor when a current flows in said at least one winding which is sufficient to overcome the force(s) holding the rotor in that rest position, to cause the rotor to rotate in a direction from that rest position towards another a rest position. The rotor is connected to a thrust member by a mechanical linkage by which the rotational movement of the rotor is converted into substantially linear movement.

Abstract: Actuators and valve-actuator combinations are disclosed which require low power for actuation, and which are particularly suitable for use to control a valve associated with a pipeline. Such an actuator (20) comprises a thrust member (26) moveable between two end of travel positions, an annular rotor having magnetic poles, an annular magnetisable stator having at least one winding and poles with which the rotor poles are aligned in each of a plurality of rotational positions of the rotor relative to the stator, and a drive connection between the rotor and the thrust member which is adapted to convert rotational movement of the rotor into linear movement of the thrust member. The actuator is able to hold its position using minimal energy, and may be located within or around an associated pipe.

Abstract: An electromagnetic actuator is described in which a rotor comprising permanent magnet means is rotatable in a stator which is magnetisable by causing an electric current to flow through at least one winding associated with the stator. The rotor has at least two stable rest positions, each defined by spring and/or magnetic forces acting on the rotor. Spring means stores energy during part of the movement of the rotor and provides kinetic energy for accelerating the rotor during subsequent movement thereof away from rest in one position towards another. A magnetic torque is exerted on the rotor when a current flows in said at least one winding which is sufficient to overcome the force(s) holding the rotor in that rest position, to cause the rotor to rotate in a direction from that rest position towards another a rest position. The rotor is connected to a thrust member by a mechanical linkage by which the rotational movement of the rotor is converted into substantially linear movement.