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SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising: a valve housing; a valve element (4) moveable between a closed position in which it is in sealing abutment with a valve seat, and an open position; a spring element urging the valve element to the closed po

SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising: a valve housing; a valve element (4) moveable between a closed position in which it is in sealing abutment with a valve seat, and an open position; a spring element urging the valve element to the closed position; a SMA wire (1) extending between a fixed point and the valve element (4), and which is arranged such that shortening of the SMA wire upon exceeding its threshold temperature exerts a force on the valve element (4) pulling it from the closed to the open position; a conductor (20) arranged to close an electrical circuit when the valve element reaches its open position; a control unit for supplying electrical power to the SMA wire for opening the valve and to detect closure of the electrical circuit, and arranged to reduce the electrical power supply to the SMA wire when detecting closure of the electrical circuit, wherein the suspension (8, 10, 10′, 12, 12′, 14, 14′) of the valve element is arranged such that the valve element moves parallel to the mounting plate (30) between the closed and open positions; and an actuator arm (16) fixed to and extending from the suspension is arranged such that it, upon movement of the valve element to the open position, pivots towards the mounting plate bringing the conductor (20) into contact with a contact area (34) on the mounting plate.

대표청구항 ▼

1. An SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising: a valve housing,a valve element moveably suspended with respect to a mounting plate in the housing and moveable between a closed position in which the valve element is in sealing abutment with a valve

1. An SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising: a valve housing,a valve element moveably suspended with respect to a mounting plate in the housing and moveable between a closed position in which the valve element is in sealing abutment with a valve seat establishing a closed state of the valve, and an open position in which the valve element is moved away from the valve seat corresponding to an open state of the valve,a spring element adapted to exert a bias force on the valve element urging the valve element to the closed position,an SMA wire extending between a point fixed in the housing and the valve element, and arranged such that shortening of the SMA wire upon exceeding a threshold temperature exerts a force on the valve element which pulls the valve element away from the closed position to the open position against the bias force of the spring element,a conductor arranged with respect to the mounting plate such that the conductor is moved into contact with contact area on the mounting plate to close an electrical circuit as a result of the valve element reaching the open position, and the conductor is moved away from the contact area when the valve element leaves the open position,a control unit arranged to supply electrical power to the SMA wire for opening the valve and to detect closure of the electrical circuit, and arranged to reduce the electrical power supply to the SMA wire when detecting closure of the electrical circuit,wherein a suspension of the valve element is arranged such that the valve element moves relative to the mounting plate between the closed and open positions, and wherein an actuator arm is fixed to and extends from the suspension and is arranged such that, upon movement of the valve element from the closed to the open position, the actuator arm moves towards the mounting plate to bring at least a portion of the conductor into contact with the contact area on the mounting plate. 2. The SMA valve according to claim 1, wherein the conductor comprises a portion in contact with the mounting plate and an elastic cantilever arm protruding with a free end of the cantilever arm to a position above the contact area on the mounting plate, and the actuator arm is arranged such that the actuator arm is, upon moving as a result of the movement of the valve element from the closed to the open position, moved by the suspension to contact the elastic cantilever arm and to press the free end of the elastic cantilever arm into contact with the contact area on the mounting plate. 3. The SMA valve according to claim 2, wherein the suspension is further defined as a parallelogram suspension which comprises a mounting body connected to the mounting plate, two parallel connecting links extending between the mounting body and the valve element at a distance from each other in moving direction of the valve element, the first connecting link being connected to the mounting body by a first hinge and to the valve element by a first valve element hinge, the second connecting link being connected to the mounting body by a second hinge and to the valve element by a second valve element hinge, wherein the connecting links are arranged such that the connecting links pivot over an angular range with respect to a longitudinal direction of the valve element and the moving direction of the valve element when the valve element moves between the closed and open positions, the angular range including a 90° angle between the connecting links and the longitudinal and moving directions. 4. The SMA valve according to claim 3, wherein the mounting body, the first connecting link, the second connecting link, the valve element, and the hinges are integrally formed of plastic material and the first and second hinges and the first and second valve element hinges are solid state hinges with each hinge having a zone of weakened material thickness. 5. The SMA valve according to claim 4, wherein the SMA wire extends from a first fixation means stationary with respect to the mounting body and located behind an arrangement of the valve element and the suspension in the direction of movement of the valve element from the closed to the open position, towards the arrangement, past the arrangement along a first side thereof, around a front face portion of the first connecting link, in a symmetrical manner back along an opposite side of the arrangement, and further to a second fixation means behind the arrangement. 6. The SMA valve according to claim 4, wherein the actuation arm protrudes from the second connecting link in a direction away from the valve element and downwardly towards a rearward extension extending from the mounting body such that the actuation arm is pivoted with the second connecting link upon movement of the valve element from the closed position to the open position and pivoted further downwardly such that the outer end of the actuation arm comes into contact with the elastic cantilever arm of the conductor to press the conductor down into contact with the contact area on the mounting plate. 7. The SMA valve according to claim 3, wherein the SMA wire extends from a first fixation means stationary with respect to the mounting body and located behind an arrangement of the valve element and the suspension in the direction of movement of the valve element from the closed to the open position, towards the arrangement, past the arrangement along a first side thereof, around a front face portion of the first connecting link, in a symmetrical manner back along an opposite side of the arrangement, and further to a second fixation means behind the arrangement. 8. The SMA valve according to claim 7, wherein the fixation means of the SMA wire is located on a rearward extension extending the mounting body in the direction of movement of the valve element from the closed to the open position. 9. The SMA valve according to claim 8, wherein the front face portion of the first connecting link around which the SMA wire is routed is located at a lower end portion of the first connecting link close to the first hinge. 10. The SMA valve according to claim 8, wherein the SMA wire extends rectilinearly towards and along the arrangement in a direction essentially parallel to the movement direction of the valve element from the closed to the open position. 11. The SMA valve according to claim 7, wherein the front face portion of the first connecting link around which the SMA wire is routed is located at a lower end portion of the first connecting link close to the first hinge. 12. The SMA valve according to claim 11, wherein the SMA wire extends rectilinearly towards and along the arrangement in a direction essentially parallel to the movement direction of the valve element from the closed to the open position. 13. The SMA valve according to claim 7, wherein the SMA wire extends rectilinearly towards and along the arrangement in a direction essentially parallel to the movement direction of the valve element from the closed to the open position. 14. The SMA valve according to claim 3, wherein the actuation arm protrudes from the second connecting link in a direction away from the valve element and towards a rearward extension extending from the mounting body such that the actuation arm is moved with the second connecting link upon movement of the valve element from the closed position to the open position and moved further such that the outer end of the actuation arm comes into contact with the elastic cantilever arm of the conductor to press the conductor into contact with the contact area on the mounting plate. 15. The SMA valve according to claim 14, wherein the actuation arm is integrally formed with the second connecting link. 16. The SMA valve according to claim 1, wherein the suspension is further defined as a parallelogram suspension which comprises a mounting body connected to the mounting plate, two parallel connecting links extending between the mounting body and the valve element at a distance from each other in moving direction of the valve element, the first connecting link being connected to the mounting body by a first hinge and to the valve element by a first valve element hinge, the second connecting link being connected to the mounting body by a second hinge and to the valve element by a second valve element hinge, wherein the connecting links are arranged such that the connecting links pivot over an angular range with respect to a longitudinal direction of the valve element and the moving direction of the valve element when the valve element moves between the closed and open positions, the angular range including a 90° angle between the connecting links and the longitudinal and moving directions.