Pneumatic valve with an SMA actuator
A pneumatic valve features a fluid supply port, a fluid outlet port, and a fluid drainage opening. The valve includes a valve chamber with fluid supply, outlet, and trigger openings, and an actuator chamber connected to the trigger opening. An actuator with an SMA wire, actuating and resetting elements, and a printed circuit board is housed within the valve. A sealing element on the actuating element controls the trigger opening, while a membrane divides the valve chamber into two regions and facilitates plunger movement. The plunger connected to the membrane closes the fluid outlet opening in the unactuated state and opens it in the actuated state. The membrane includes a passage opening for fluid flow between the regions, with a smaller cross-section than the trigger opening, facilitating controlled fluid flow within the valve.
1 . A pneumatic valve comprises:
a fluid supply port,
a fluid outlet port,
a fluid drainage opening,
a valve chamber with a fluid supply opening connected to the fluid supply port, a fluid outlet opening connected to the fluid outlet port, and a trigger opening connected to an actuator chamber of the valve with the fluid drainage opening,
an actuator formed with an SMA wire, comprising an actuating element, a resetting element, and with a printed circuit board arranged in the actuator chamber,
wherein a sealing element is arranged on the actuating element, said sealing element being pressed against the trigger opening by the resetting element in a unactuated state of the actuator and opening up the trigger opening in an actuated state of the actuator, and
a membrane dividing the valve chamber into a first region connected to the trigger opening and a second region connected to the fluid outlet opening,
wherein the membrane is connected to a plunger which, using a spring force in the unactuated state of the actuator, is pressed against and closes the fluid outlet opening, in the actuated state of the actuator, is pushed away from the fluid outlet opening by a fluid flowing through the fluid supply opening and opens up the fluid outlet opening, and
wherein the membrane has at least one passage opening through which fluid can flow from the first region into the second region, the passage opening having a smaller cross section than the trigger opening.
2 . The pneumatic valve as claimed in claim 1 , wherein the valve chamber is formed with a cover element having the trigger opening.
3 . The pneumatic valve as claimed in claim 2 , wherein the spring force applied to the plunger is generated by a spiral spring arranged between the plunger and the cover element.
4 . The pneumatic valve as claimed in claim 2 , wherein the membrane is clamped between the cover element and a cup-shaped element of the valve chamber receiving the cover element.
5 . The pneumatic valve as claimed in claim 4 , wherein the cover element has a projection at its edge which is in contact with the membrane.
6 . The pneumatic valve as claimed in claim 1 , wherein the actuating element is as a leaf spring with a bending section and an actuating section.
7 . The pneumatic valve as claimed in claim 6 , in which the bending section and the actuating section of the leaf spring are each arranged on opposite sides of the printed circuit board.
8 . The pneumatic valve as claimed in claim 1 , wherein, in a region next to the trigger opening, the valve chamber has a web against which the region of the membrane, in which the passage opening is situated, is pressed by the fluid flowing in the actuated state of the actuator.
9 . The pneumatic valve as claimed in claim 1 , wherein the membrane is connected integrally to the plunger.
10 . The pneumatic valve as claimed in claim 1 , wherein a cross section of the trigger opening is smaller than the cross section of the fluid outlet opening.
11 . The pneumatic valve as claimed in claim 1 , wherein a cross section of the fluid supply opening is larger than the cross section of the fluid outlet opening.
12 . The pneumatic valve as claimed in claim 1 , wherein an effective area of the membrane is larger than the cross section of the fluid outlet opening.
13 . The pneumatic valve as claimed in claim 1 , wherein the fluid outlet opening of the valve chamber is connected to the fluid outlet port via a second valve element.
14 . The pneumatic valve as claimed in claim 13 , in which the second valve element is open in its unactuated state, and therefore the pneumatic valve is a 3/3 NO valve.
15 . The pneumatic valve as claimed in claim 13 , in which the second valve element is closed in its unactuated state, and therefore the pneumatic valve is a 3/3 NC valve.