Pneumatic valve

Abstract

Pneumatic valve comprising a valve housing (2) in which an air chamber (18) with one or more air ports (3, 3', 4) is arranged, wherein each air port (3, 3') of at least some of the air ports (3, 3', 4) can be opened and closed by means of a movable valve flap (8), wherein the valve flap (8) is mechanically coupled to a shape memory alloy (SMA) element (7), wherein the SMA element (7) deforms upon application of an electric heating current and thereby causes a predetermined movement of the valve flap (8) to open or close the respective air port (3, 3'), wherein the deformation of the SMA element (7) is reversed upon termination of the electric heating current and thereby causes a reversal of the predetermined movement of the SMA element (7), wherein the valve flap (8) comprises a leaf spring (10) with a spring leaf (10a),wherein the leaf spring (10) is held rotationally fixed relative to the valve housing (2) and interacts with the SMA element (7) in such a way that a stroke of the SMA element (7), caused by its deformation, is converted into a stroke of the valve flap (8) by means of elastic bending of the leaf (10a) of the leaf spring (10), wherein the stroke of the valve flap (8) is greater than the stroke of the SMA element (7), wherein the leaf spring (10) interacts with the SMA element (7) in such a way that the stroke of the valve flap (8) is deflected relative to the stroke of the SMA element (7), wherein the SMA element (7) is a wire extending in a plane, which is contracted by the supply of the electric heating current and thereby causes the predetermined movement of the valve flap (8), wherein the wire runs parallel to the leaf (10a) of the leaf spring (10) at a predetermined distance from it, and the wire has two straight sections (701,702) with an intermediate curved section (703), wherein the stroke of the wire is transmitted via the curved section (703) to the valve flap (8), the curved section (703) rotating the extension direction of the wire by 180°.

Description

[0001] The invention relates to a pneumatic valve.

[0002] Pneumatic valves are used to control air flow in a wide variety of technical applications. It is common practice to use so-called SMA elements made of a shape memory alloy, such as NiTi, to actuate such valves. The SMA elements are deformed by the flow of current and the resulting heating. After subsequent cooling, they can be returned to their original shape.

[0003] SMA elements in the form of wires are often used to actuate pneumatic valves. The actuator stroke is achieved by contracting the wire using a current supply. To achieve a long service life and thus a high number of actuation cycles, the contraction of the wire during valve actuation should be as minimal as possible. Accordingly, there are various approaches to converting the wire contraction into a larger valve stroke using geometric translation.

[0004] The document DE 102 57 549 B3 shows a mechanical series connection of SMA wires to increase the actuating stroke of a valve.

[0005] The documents WO 2015 / 185 132 A1 and WO 2015 / 086 089 A1 show pneumatic SMA valves in which the stroke of an SMA wire is converted into the movement of a valve element via joints.

[0006] The document DE 10 2005 060 217 A1 shows a pneumatic valve with triangularly tensioned SMA wires to which tappets are attached for opening and closing valve openings.

[0007] The document DE 10 2012 222 570 A1 shows another pneumatic valve with a triangularly tensioned SMA wire.

[0008] Document DE 10 2005 059 081 A1 discloses a rotary actuator with a tension element made of shape memory alloy. The actuator converts a tensile movement of the tension element into a rotary movement.

[0009] Document DE 101 62 498 A1 discloses a multi-way valve having multiple inlets and outlets and a chamber with multiple seats, each associated with an inlet or outlet, a closing member movable between the seats, and at least one actuator in the form of an element made of a shape memory alloy capable of displacing the closing member from one of the seats when heated. A spring element presses the closing member against each seat it occupies.

[0010] Document WO 2014 / 154239 A1 discloses an automotive positive displacement pump with a pumping chamber accessible via a check valve. The check valve has a valve body covering a valve opening. A valve limiter is also provided, which has a mechanical temperature element. This temperature element increases the valve travel as the temperature decreases and decreases it as the temperature increases.

[0011] The document DE 10 2012 212 686 A1 discloses a valve with a housing enclosing a pressure chamber, a valve element arranged in the pressure chamber and an SMA element that actuates the valve element.

[0012] The document WO 2005 / 026592 A2 discloses a valve system having a plurality of valves actuated by shape memory alloy elements.

[0013] The object of the invention is to create a reliably operating pneumatic valve with at least one SMA element as actuator.

[0014] This object is achieved by the pneumatic valve according to claim 1. Further developments of the invention are defined in the dependent claims.

[0015] The pneumatic valve according to the invention comprises a valve housing in which an air chamber with one or more air connections is arranged, wherein a respective air connection of at least some of the air connections can be opened and sealed by means of a movable valve flap. The valve flap is mechanically coupled to an SMA element, and in particular a wire-shaped SMA element made of a shape memory alloy (e.g., a NiTi alloy). In a manner known per se, the SMA element deforms upon the supply of an electric heating current, causing a predetermined movement of the valve flap to open or close the respective air connection. The deformation of the SMA element is reversed upon termination of the supply of the electric heating current, causing a reversal of the predetermined movement of the SMA element.

[0016] The valve cap of the pneumatic valve according to the invention comprises a leaf spring, preferably made of metal, with a spring leaf and preferably a single spring leaf, wherein the leaf spring is held in a rotationally fixed, i.e., hingeless, manner relative to the valve housing. Preferably, the leaf spring is attached (hingeless) directly to the valve housing. The valve flap with the leaf spring interacts with the SMA element in such a way that a stroke of the SMA element, caused by its deformation, is converted into a stroke of the valve flap by means of elastic bending of the spring leaf of the leaf spring. The stroke of the valve flap is greater than the stroke of the SMA element.

[0017] The valve according to the invention uses a leaf spring to generate an increased stroke of a valve flap. The leaf spring can be attached without play and without the need for a hinge, thus ensuring reliable valve operation. Furthermore, the elastic bending of the leaf spring during valve operation ensures a peeling movement of the valve flap, which allows even a valve flap stuck to the valve seat to be easily released. By converting the stroke of the SMA element into an increased valve stroke, minimal deformation of the SMA element is required to actuate the valve, thus increasing its service life. The increase in stroke is preferably achieved via a lever arrangement.

[0018] The valve according to the invention is characterized in that the leaf spring interacts with the SMA element in such a way that the stroke of the valve flap is deflected relative to the stroke of the SMA element. The angle by which the stroke of the valve flap is deflected relative to the stroke of the SMA element is preferably between 50° and 130°, in particular between 70° and 100°, and particularly preferably 90°, with the specified angles referring to the smaller angle between the directions of the two strokes. This allows a compact design of the valve according to the invention to be achieved.

[0019] In the valve according to the invention, the SMA element is a wire extending substantially in a plane, which is contracted by supplying the electric heating current and thereby causes the predetermined movement of the valve cap.

[0020] The wire, extending in a plane, runs essentially parallel to the leaf of the flat spring at a predetermined distance from it. This predetermined distance allows a short lever to engage the SMA element, thereby increasing the stroke.

[0021] The wire has two straight sections with a bent section between them. The stroke of the wire is transmitted to the valve flap via the bent section. The bent section rotates the direction of extension of the wire by 180°. The bent section can, for example, engage a projection of the valve flap. This variant of the invention ensures a simple mechanical coupling of the wire to the valve flap.

[0022] In a further preferred variant, the leaf spring comprises a support area that rests on a section of the valve housing, wherein the support area lifts off from the section of the valve housing upon elastic bending of the leaf spring. This enables a simple and compact arrangement of the leaf spring on the valve housing.

[0023] In a further embodiment of the valve according to the invention, a restoring force acts on the valve flap, causing the movement of the valve flap to reverse when the supply of the heating current is terminated. Depending on the design, the restoring force can be exerted by the leaf spring itself, which can be ensured by appropriate preloading of the leaf spring. Alternatively or additionally, a separate spring can be provided to apply the restoring force.

[0024] In a further variant of the valve according to the invention, the valve flap comprises a valve body, in particular made of plastic, which has a first side facing the respective air connection and a second side which is a side opposite (i.e. opposite) to the first side. A section of the spring leaf, which is moved by the elastic bending of the leaf spring, is arranged on the first side. Preferably, the SMA element is mechanically coupled to the valve flap on the second side. This arrangement ensures a stable valve flap. Furthermore, the valve body can be used to ensure a spacing of the SMA element from the leaf spring and thus a suitable lever arm.

[0025] In a further variant of the valve according to the invention, the valve housing comprises a base plate made of non-conductive material, in particular plastic. The base plate is preferably an injection-molded component. The base plate divides the interior of the valve housing into the air chamber, which is sealed from other areas, and a region separated from the air chamber. An electronic control unit for controlling the valve flap or flaps for opening or closing the respective air connection(s) is preferably arranged in the separate region. By means of this variant of the invention, sensitive components can be protected from the air flow in the air chamber as well as from moisture in the air chamber.

[0026] In another variant, in which a support area of ​​the spring leaf rests on a section of the valve housing, the section of the valve housing is part of the base plate just described, on the side facing the air chamber. This achieves a compact valve design.

[0027] In a further, particularly preferred embodiment, the SMA element is guided through a shielding wall that shields a portion of the SMA element from the respective air connection. The shielding wall is preferably attached to the valve flap or the valve housing. In this embodiment, a change in the behavior of the SMA element due to cooling by the air flow at the air connection is avoided.

[0028] In a further variant of the valve according to the invention, a conductive section is formed on the leaf spring, which electrically bridges a portion of the SMA element when the valve flap reaches an end position upon application of the electrical heating current. This variant of the invention enables simplified detection of the end position, since the reduction in resistance caused by the electrical bridging can be used to detect the end position.

[0029] In a further embodiment of the valve according to the invention, a non-controllable air connection, i.e. an air connection without a valve flap, is located at one end of the valve housing. Furthermore, the valve comprises two air connections which contain valve flaps and a corresponding actuation with an SMA element according to the above embodiments. In one variant, the two air connections are arranged at the end of the valve housing at which the non-controllable air connection is located. This ensures that the air flow is only partially guided past the SMA element and thus does not negatively influence the properties of the SMA element. Alternatively, it is also possible for one of the two air connections to be arranged at the end of the valve housing at which the non-controllable air connection is located, and the other of the two air connections to be arranged at an end of the valve housing opposite this end.This allows for a compact, elongated design of the valve housing. If necessary, more than the two air connections mentioned can be provided. However, preferably, exactly two such air connections are provided.

[0030] The pneumatic valve according to the invention is preferably intended for filling and / or emptying at least one elastic air bladder in a device for pneumatically adjusting a seat in a means of transport. In other words, the invention also encompasses a device for pneumatically adjusting a seat in a means of transport with at least one elastic air bladder and a valve according to the invention for filling and / or emptying the at least one air bladder.

[0031] Embodiments of the invention are described in detail below with reference to the attached figures.

[0032] They show: Fig. 1 and Fig. 2 sectional views through a first embodiment of a valve according to the invention in the closed and open position of an air connection; Fig. 3 a plan view of the embodiment of the valve from Fig. 1 and Fig. 2; Fig. 4 is a plan view of a second embodiment of a valve according to the invention; and Fig. 5 a perspective view of a modified embodiment of a valve flap used in the valve according to the invention.

[0033] Embodiments of the invention are described below using pneumatic 3 / 3 valves used for filling and deflating an elastic air bladder (not shown) in a device for pneumatically adjusting a motor vehicle seat. Nevertheless, the pneumatic valves described below can also be used for any other purposes.

[0034] Fig. Figure 1 shows a sectional view through a first embodiment of a pneumatic valve according to the invention. The section runs along line II of the plan view of Fig. 3, whereby components located outside the cutting plane are also Fig. 1 can be seen.

[0035] The Fig. The valve shown in Figures 1 to 3 is designated by reference numeral 1 and comprises a valve housing 2 in which several air connections are formed. Fig. 3 shows, among other things, the non-controllable working connection 4, through which air is supplied to or discharged from an air bladder by means of the valve. Furthermore, the valve contains the two additional air connections 3 and 3', which consist of Fig. 1. The air connection 3 is an exhaust air connection through which air is directed from the valve to the outside. A damping element 6 is provided adjacent to the air connection to reduce noise from the valve 1 escaping to the outside.

[0036] In contrast to air connection 3, air connection 3' is an air supply connection connected to an air duct 5, which in turn is connected to a compressed air supply (not shown). Air connections 3 and 3' are controllable by means of movable valve flaps 8, i.e., the respective air connections can be opened and sealed via the valve flaps. The individual valve flaps 8 comprise, among other components, a plastic valve body 9 and a metal leaf spring 10, as will be explained in more detail below.

[0037] The following are based on Fig. 1 to Fig. 3 explains the opening and closing of the exhaust air connection 3 by means of the valve flap 8 shown, wherein the same actuating mechanism for opening and closing the air connection 3' is provided analogously, as can be seen from the top view of Fig. 3 results.

[0038] According to Fig. 1, an SMA wire 7 made of a known shape memory alloy is stretched horizontally. The wire 7 is attached to the valve housing 2 and to corresponding contact pins 15 by crimping using metallic crimp elements 20. The exact crimp connection is not essential for the invention and is therefore Fig. 1 to Fig. 3 is not shown in detail. Electrical heating current is supplied to the wire via contact pins 15. For this purpose, the contact pins 15 are connected to a circuit board 17 in the lower area of ​​the housing 2, which controls the supply of electrical heating power. The voltage for supplying the heating power originates, for example, from the vehicle's electrical system.

[0039] From the top view of the Fig. 3 shows the routing of the wire 7. As can be seen, the wire is attached to the housing at its right ends via respective crimp elements 20. The wire extends in Fig. 3, starting from an upper crimp element 20 and an upper contact pin 15, initially as a straight section 701 in the direction of the valve flap. There, it is guided as a bent section 703 around a cylinder 11 protruding from the valve flap. The wire then ends again in a straight section 702, which leads to another crimp element 20, which is connected to a central contact pin 15 via an electrically conductive web 22. The cylinder 11 is an integral part of the plastic valve body 9. As can be seen from Fig. As can be seen in Figure 1, a spiral spring 12 is located around the cylinder 11, which biases the valve flap downward to close the air connection 3. A cover 202 of the housing 2 forms the abutment for the spring 12.

[0040] The valve housing 2 comprises, in addition to the cover 202 and a base cover 203, a hatched base plate 201, which Fig. 1 is shown in section. The base plate has circumferential walls and contains the air connections 3, 3', 4 and the air duct 5. The base plate divides the valve housing 2 into an air chamber 18, in which the valve flap 8 and its mechanical actuation mechanism, including the SMA wire 7, are located, and into an area 19 separated from the air chamber, in which the printed circuit board 17 with its electronic components is located. The air chamber 18 is pressure-tightly sealed from the valve environment and from the separated area 19. The printed circuit board is thus protected from the air flow guided through the air chamber 18.

[0041] As already mentioned, the contact pins 15 are connected to the circuit board 17. These pins are guided into the air chamber 18 via sealed feedthroughs 16 in the base plate 201, where they are connected to the SMA wire 7. The base plate 201 is made of dimensionally stable plastic and is additionally stabilized by the cover 202 and the base cover 203. The cover can be glued or welded to the base plate 201. Since the electrical components of the valve are located on the separate circuit board 17, the base plate 201 does not require any electrical conductor tracks, so it can be made of plastic. In particular, it is an injection-molded component, which enables the integral formation of the air connections 3, 3', and 4 in the base plate. The material used for the base plate is preferably a low-warpage and torsion-resistant plastic, if necessary.An insert can also be provided in the area of ​​the nozzles of the individual air connections, or the plastic in these places can be made of a different material. For example, the area of ​​the valve nozzles can be made of a plastic without fiber reinforcement, while the rest of the base plate contains such fibers to increase its stability. Using non-reinforced plastic in the area of ​​the nozzle seats can improve the seal when the connections are closed.

[0042] As already mentioned, the contact pins 15 are routed through the base plate 201 via feedthroughs 16. The base plate also has the task of sealing the contact pins. This can be done by injecting the corresponding pins, pressing them in (possibly through an elastic seal), or gluing them.

[0043] The valve flap 8 comprises, in addition to the valve body 9, the leaf spring 10, which comprises the actual spring leaf 10a, which in Fig. 1 perpendicular to the leaf plane and thus in a horizontal direction. The spring leaf is a flat metal plate. At the right end of the leaf spring there are also two vertically running vanes 10b with a rectangular cross-section. The vanes are also visible from the top view of the Fig. 3. There, it can also be seen that the tabs are accommodated in corresponding recesses in the walls of the base plate 201, thereby securing the leaf spring 10 to the base plate 201 and thus to the valve housing 2. Alternatively, the leaf spring can also be secured to the base plate 201 in its right-hand area by other joining methods such as gluing, riveting, or the like; in this case, the vertical tabs are omitted.

[0044] Out of Fig. 3 also shows the shape of the valve body 9. As can be seen, the valve body 9 has a significantly smaller width than the underlying spring leaf 10a of the leaf spring 10. At the left front end of the valve body 9, a nose 9a ( Fig. 1) is provided with an undercut into which the front end of the spring leaf 10a is inserted. In this way, the spring leaf 10a and the underside of the valve body 9 are fastened together. Additionally, the valve body can be glued to the leaf spring. A sealing element 14 made of soft plastic is also provided on the underside of the spring leaf 10a. When the air connection 3 is closed, this sealing element rests on the conical nozzle seat of this air connection and ensures a tight seal.

[0045] On the underside of the valve body 9, at its right-hand end, there is also a bulge 9b that contacts the upper side of a section of the spring leaf 10a that rests on the base plate 201. This bulge facilitates the lifting of the leaf spring when opening the valve flap 8, as will be described in more detail below. On the upper side of the valve body 9 there is also a shield 13 with two upwardly open slots through which the two straight sections 701 and 702 of the SMA wire 7 are guided. By means of this shield, a large part of the SMA wire 7 is insulated from the air flow in the area of ​​the air connections. This ensures consistent behavior of the shape memory alloy of the wire, since the temperature of the wire is not changed by passing air, which would otherwise influence its properties.The shield 13 can also be molded onto the cover 10 instead of onto the valve body 9. This simplifies the installation of the SMA wire, as it no longer needs to be inserted through slots during installation into the housing. The cover 202 is only attached once the wire is already installed.

[0046] The following explains the function of opening and closing the valve flap 8 using the SMA wire 7. In Fig. 1 shows the closed state of the air connection 3. To open this air connection, an electric heating current is supplied to the SMA wire 7 via the contact pins 15, which causes the wire 7 to heat up. In a conventional manner, heating the wire causes a transformation of the crystal structure of the shape memory material of the wire, resulting in its shortening. This shortening, in turn, results in a force in the bent section 703 of the wire acting on the cylinder 11 and thus on the valve flap 8 as a whole. As a result, the leaf spring 10 and thus the valve flap 8 are pulled upwards under elastic bending of the spring leaf 10a. The spring leaf 10a thereby detaches from its corresponding support on the upper side of the base plate 201 in the area of ​​the bulge 9b. Fig. 2 shows the raised state of the valve flap 8 with the air connection 3 open.

[0047] After the valve has reached the Fig. 2, this end position is detected by means of a suitable limit switch (not shown). As a result, the heating current is reduced in order to avoid thermal and mechanical overloading of the wire 7. To close the air connection 3, the supply of heating current is finally completely interrupted, with the result that the wire expands again due to the shape memory alloy and the restoring force of the spring 12 causes the valve flap 8 to move downwards and thus closes the air connection 3. If necessary, the use of a separate spring 12 to generate the restoring force can be dispensed with. Instead, the restoring force can also be generated by a suitable preload of the spring leaf 10a of the leaf spring 10.

[0048] The arrangement for the mechanical coupling of SMA wire 7, leaf spring 10 and valve body 9 was designed according to Fig. 1 and Fig. 2 is selected such that a mechanism is formed which, on the one hand, converts the horizontal stroke of the SMA wire 7 (i.e. its shortening when the heating current is applied) into a vertical stroke of the valve flap 8 and, on the other hand, increases the stroke of the valve flap 8 compared to the stroke of the SMA wire 7. This is achieved by a lever arrangement or a rocker. The shorter lever, on which the SMA wire 7 acts, is given by the distance between the wire 7 and the spring leaf 10a. The longer lever, which acts on the valve flap 8 or the sealing element 14, is given by the distance between the bulge 9b and the center of the sealing element 14 (i.e. the nozzle seat). This arrangement also deflects the direction of force of the SMA wire 7 by approximately 90° in the direction of the stroke of the valve flap 8. If necessary, other designs are also conceivable in which the direction of force is changed by a different angle.Preferably, the direction of force is changed by an angle between 50° and 130°, especially between 70° and 110°. A 90° redirection of the force direction enables a particularly compact valve design.

[0049] The use of a leaf spring 10 for opening and closing the air connection 3 has particular advantages. In particular, this ensures that the valve flap 8 is guided in its movement and always contacts the nozzle seat in the same position by means of its sealing element 14. The leaf spring 10 simultaneously supports the longitudinal force when the valve flap is actuated against the base plate 201. In contrast to hinges, the leaf spring enables a play-free and low-friction mounting of the valve flap, thereby improving the reliability of opening and closing the air connection. At the same time, this mounting creates a peeling movement of the valve flap during opening, preventing the valve from "hanging" due to an adhesive sealing element 14.

[0050] How to Fig. 3, the two air connections 3 and 3' with the corresponding valve flaps are arranged offset from each other in the area of ​​the working connection 4. The electrical contact of the two SMA wires is made via the contact pins 15 at the right end of the housing. A common contact pin 15 is used as a ground pin for both SMA wires. The ground pin 15 is connected to the adjacent crimp elements of the two wires 7 via the conductive web 22. Fig. The arrangement of all three air connections 3, 3', and 4 on one side of the housing 2, as shown in Figure 3, ensures that the air flow flowing through these air openings is limited to a small area within the housing and thus comes into contact with the SMA wires as little as possible, thereby ensuring consistent contraction and expansion behavior of the wires. This is further supported by the shields 13 on the top side of the valve bodies 9, as already explained above.

[0051] Fig. Figure 4 shows a plan view of a modified second embodiment of a valve according to the invention. This embodiment differs from the embodiment of Fig. 3 in that the air connections 3 and 3' are no longer located on the same side of the valve housing 2. Rather, only the supply air connection 3' is located at the end of the valve housing adjacent to the working connection 4, whereas the exhaust air connection 3 is provided at the opposite end of the valve housing 2. This results in a particularly compact design of the valve.

[0052] The design of the Fig. 4 differs from the design of the Fig. 3 further in that one-piece components 21 consisting of a pair of crimp elements 20 are used to fasten the wires 7 to the valve housing 2. The components 21 are inserted into the base plate 201 and have the crimp elements 20 at both of their ends. There are three such components 21, whereby in the upper component 21 only the left crimp element 20 and in the lower component 21 only the right crimp element 20 is used to fix the wires. In contrast, in the middle component 21 both crimp elements 20 are used to fix the wires. In analogy to Fig. 3, three contact pins 15 are provided, with the middle contact pin 15 forming a common ground connection for both SMA wires 7. The contact pins contact the wires, for example, they can be welded to them. This ensures the supply of heating current to the wires.

[0053] Fig. Figure 5 shows a perspective view of a modification of a valve flap that can be used in the valve according to the invention. In contrast to the valve flap of the previous embodiments, the valve flap 8 of the Fig. 5 now consists only of a leaf spring 10 and a sealing element 14, without a plastic valve body. This ensures simple production of the valve flap.

[0054] In analogy to Fig. 1 includes the leaf spring of the Fig.5 shows the spring leaf 10a and two vertically extending lugs 10b, which, in contrast to the previous embodiments, now extend downward. The lugs 10b, in turn, secure the leaf spring or the valve flap in the valve housing 2. The leaf spring is made of metal and, in addition to the lugs 10b, comprises the semicircular section 10c and an upwardly bent section 10d, which ends at a wing 10e that runs perpendicular to the direction of extension of the straight sections of the SMA wire 7. The lugs 10b, the semicircular section 10c, the bent section 10d, and the wing 10e are formed by punching and bending a corresponding metal plate, so that the leaf spring forms an integral component.

[0055] To move the valve flap 8, the wire 7 is again contracted and deflected via the semicircular section 10c. This contraction transfers force via the semicircular section 10c to the leaf spring 10, thereby lifting the valve flap with the corresponding sealing element 14 from the nozzle seat. The geometric shape of the leaf spring is selected such that when the end position is reached in the open state of the nozzle seat, the metallic wing 10e electrically bridges both straight sections of the wire 7. This leads to a change in the resistance of the SMA wire, which is detected by a suitable resistance measurement, so that the end position of the wire can be detected and the heating current can subsequently be reduced.

[0056] The embodiments of the invention described above have a number of advantages. In particular, a lever arrangement using a leaf spring increases and deflects the stroke of the SMA wire. The stroke of the SMA wire is very small (e.g., contraction by only approximately 0.5% to 1% of its length), thereby increasing its service life. This stroke is converted by the lever arrangement into a stroke of the valve flap, which is generally 2 to 3 times greater than the stroke of the SMA wire. The use of a leaf spring also achieves a peeling removal of the sealing element from the nozzle seat, whereby even well-adhering sealing elements can be reliably lifted from the nozzle seat. Furthermore, a simple and reliable, play-free mounting of the valve flap is enabled.

[0057] A base plate can also be used to create a separate area in the valve housing from the air chamber. Electronic components can then be installed in this area, protected from air flow and humidity in the air chamber. Furthermore, the use of a shield through which the SMA wire is routed can reduce the air flow past this wire, thus ensuring consistent wire behavior.

[0058] Furthermore, the arrangement of the valve seats toward the valve housing cover and the integral design of the seats in the base plate ensure simple valve manufacturing and assembly. In particular, the valve flap actuation mechanism is located in an easily accessible area of ​​the housing, facilitating assembly and quality control of the components. List of reference symbols 1 valve 2 valve housings 201 base plate 202 lid 203 Ground cover 3, 3', 4 air connections 5 Air duct 6 Damping element 7 SMA wire 701, 702 straight sections of the wire 703 bent section of the wire 8 valve flap 9 Valve body 9a Nose 9b bulge 10 leaf spring 10a spring leaf 10b Flag 10c semicircular section 10d curved section 10th wing 11 cylinders 12 spiral spring 13 Shielding 14 Sealing element 15 contact pin 16 Implementation 17 Circuit board 18 air chamber 19 Area separated from the air chamber 20 crimp elements 21 Component with crimp elements 22 conductive bridge

Claims

[1] Pneumatic valve, comprising a valve housing (2) in which an air chamber (18) with one or more air connections (3, 3', 4) is arranged, wherein a respective air connection (3, 3') of at least some of the air connections (3, 3', 4) can be opened and sealed by means of a movable valve flap (8), wherein the valve flap (8) is mechanically coupled to an SMA element (7) made of a shape memory alloy, wherein the SMA element (7) is deformed by the supply of an electric heating current and thereby causes a predetermined movement of the valve flap (8) for opening or closing the respective air connection (3, 3'), wherein the deformation of the SMA element (7) is reversed upon termination of the supply of the electric heating current and thereby causes a reversal of the predetermined movement of the SMA element (7), wherein the valve flap (8) has a leaf spring (10) with a spring leaf (10a) includes,wherein the leaf spring (10) is held in a rotationally fixed manner relative to the valve housing (2) and interacts with the SMA element (7) in such a way that a stroke of the SMA element (7), which is caused by its deformation, is converted into a stroke of the valve flap (8) by means of elastic bending of the spring leaf (10a) of the leaf spring (10), wherein the stroke of the valve flap (8) is greater than the stroke of the SMA element (7), wherein the leaf spring (10) interacts with the SMA element (7) in such a way that the stroke of the valve flap (8) is deflected relative to the stroke of the SMA element (7), wherein the SMA element (7) is a wire extending in a plane, which is contracted by the supply of the electric heating current and thereby effects the predetermined movement of the valve flap (8), wherein the wire runs parallel to the spring leaf (10a) of the leaf spring (10) at a predetermined distance therefrom, and the wire has two straight sections (701,702) with a bent section (703) located therebetween, wherein the stroke of the wire is transmitted to the valve flap (8) via the bent section (703), wherein the bent section (703) rotates the extension direction of the wire by 180°., [2] Pneumatic valve according to claim 1, characterized by that the angle by which the stroke of the valve flap (8) is deflected relative to the stroke of the SMA element (7) is between 50° and 130°. [3] Pneumatic valve according to one of the preceding claims, wherein the spring leaf (10a) of the leaf spring (10) comprises a support area which rests on a section of the valve housing (2), wherein the support area lifts off from the section of the valve housing (2) during the elastic bending of the spring leaf (10a). [4] Pneumatic valve according to one of the preceding claims, wherein a restoring force acts on the valve flap (8) which causes the reversal of the predetermined movement of the valve flap (8) upon termination of the supply of the heating current, wherein the restoring force is generated by the leaf spring (10). [5] Pneumatic valve according to one of the preceding claims, wherein a restoring force acts on the valve flap (8) which causes the reversal of the predetermined movement of the valve flap (8) upon termination of the supply of the heating current, wherein the restoring force is generated by a separate spring (12). [6] Pneumatic valve according to one of the preceding claims, wherein the valve flap (8) comprises a valve body (9) having a first side facing the respective air connection (3, 3') and a second side opposite to the first side, wherein a portion of the spring leaf (10a) moved by the elastic bending of the leaf spring (10) is arranged on the first side and wherein the SMA element (7) is mechanically coupled to the valve flap (8) on the second side. [7] Pneumatic valve according to one of the preceding claims, wherein the valve housing (2) comprises a base plate (201) made of non-conductive material, which divides the interior of the valve housing (2) into the air chamber (18) and a region (19) separated from the air chamber (18), wherein an electronic control unit for controlling the valve flap or valve flaps (8) for opening or closing the respective air connection or connections (3, 3') is arranged in the separated region (19). [8] Pneumatic valve according to claim 7, wherein the portion of the valve housing (2) on which the support region of the spring leaf (10a) rests is a part of the base plate (201) on its side facing the air chamber (18). [9] Pneumatic valve according to one of the preceding claims, wherein the SMA element (7) is guided through a shielding wall (13) which shields a partial section of the SMA element (7) from the respective air connection (3, 3'), wherein the shielding wall (13) is fastened to the valve flap (8). [10] Pneumatic valve according to one of claims 1 to 8, wherein the SMA element (7) is guided through a shielding wall (13) which shields a partial section of the SMA element (7) from the respective air connection (3, 3'), wherein the shielding wall (13) is fastened to the valve housing (2). [11] Pneumatic valve according to one of the preceding claims, wherein a conductive section (10e) is formed on the leaf spring (10), which electrically bridges a partial section of the SMA element (7) when an end position of the valve flap (8) is reached when the electric heating current is supplied. [12] Pneumatic valve according to one of the preceding claims, wherein a non-controllable air connection (4) is located at one end of the valve housing (2) and the valve (1) comprises two air connections (3, 3') which belong to at least a part of the air connections with valve flap (8), wherein the two air connections (3, 3') are arranged at the end of the valve housing (2) at which the non-controllable air connection (4) is located. [13] Pneumatic valve according to one of claims 1 to 11, wherein a non-controllable air connection (4) is located at one end of the valve housing (2) and the valve (1) comprises two air connections (3, 3') which belong to the at least part of the air connections with valve flap (8), wherein one of the two air connections (3') is arranged at the end of the valve housing (2) at which the non-controllable air connection (4) is located, and the other of the two air connections (3) is arranged at an end of the valve housing (2) opposite this end.

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