SMA Valve for Controlling Pressurized Air Supply to an Air Cell in a Vehicle Seat

摘要

SMA valve for controlling pressurized air supply to an air cell in comprising: a valve housing; a valve element (4) which is moveably suspended with respect to a mounting plate (30) in the housing between a closed position and an open position of the valve; a spring element adapted to exert a bias force on the valve element (4) to the closed position; a SMA wire (1) arranged such that shortening of the SMA wire upon exceeding its threshold temperature pulls the valve element to the closed position; a conductor (20) arranged on the valve element (4) in contact with the SMA wire (1) and arranged such that it comes into contact with a conducting surface (34) on the mounting plate (30) to close an electrical circuit when the valve element reaches its open position; a control unit arranged to supply electrical power to the SMA wire 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, characterized in that the suspension (8, 10, 10′, 12, 12′, 14, 14′) of the valve element (4) is arranged such that the valve element moves parallel to the mounting plate (30) between the closed and open positions, and the conductor (20) is arranged to extend along a first portion (22) parallel to the longitudinal and moving direction of the valve element (4) and along a second portion (24) towards the mounting plate (30) and into a slot (32) formed therein, the conducting surface (34) being located in the slot such that an exposed end of the conductor (20) comes into contact with the conducting surface (34) in the slot (32) when the valve element (4) reaches its open position.

主权项

1. A SMA valve for controlling pressurized air supply to an air cell in a vehicle seat comprising:
a valve housing, a valve element which is moveably suspended with respect to a mounting plate in the housing between a closed position in which it 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 it to the closed position, a SMA wire extending between the mounting plate 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 against the bias force of the spring element, a conductor arranged on the valve element in contact with the SMA wire and arranged such that it comes into contact with a conducting surface on the mounting plate to close an electrical circuit when the valve element reaches 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 the suspension of the valve element is arranged such that the valve element moves parallel to the mounting plate between the closed and open positions, and wherein the conductor is arranged to extend along a first portion parallel to the longitudinal and moving direction of the valve element and along a second portion towards the mounting plate and into a slot formed therein, the conducting surface being located in the slot such that an exposed end of the conductor comes into contact with the conducting surface in the slot when the valve element reaches the open position.