Pneumatic valve with SMA actuator

Abstract

A pneumatic valve having a fluid supply port (P), a fluid outlet port (A) and a fluid discharge opening (R) is proposed, having a valve chamber (14) having a fluid supply opening (FZ) connected to the fluid supply port (P), a fluid outlet opening (VH) connected to the fluid outlet port (A), and a trigger opening (VT) connected to an actuator chamber (15) of the valve, the actuator chamber has a fluid discharge opening (R); an actuator (16) which presses the sealing element (E) against the trigger opening (VT) in an unactuated state of the actuator (16) and opens the trigger opening (VT) in an actuated state of the actuator (16); a diaphragm (M) which divides the valve chamber (14) into two regions, the first region (1) being connected to the trigger opening (VT) and the second region (2) being connected to the fluid outlet opening (VH), in which the diaphragm (M) is connected to a plunger (S) which is pressed against the fluid outlet opening (VH) due to a spring force in an unactuated state of the actuator (16) and which opens the fluid outlet opening (VH) in an actuated state, in which the plunger (S) is pressed against the fluid outlet opening (VH) due to a spring force in a non-actuated state of the actuator (16). The diaphragm (M) has at least one passage opening (D) through which a fluid can flow from the first region (1) into the second region (2), the passage opening (D) having a smaller cross-section than the trigger opening (VT).

Description

[0001] The present invention relates to a pneumatic valve having a fluid supply port, a fluid outlet port and a fluid discharge opening, the pneumatic valve having a valve chamber having 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, the actuator chamber having a fluid discharge opening. The valve is formed with an actuator, the actuator is formed with an SMA wire, an actuating element, a reset element, and a printed circuit board, the actuator being arranged in the actuator chamber. The valve also has a diaphragm, the diaphragm dividing the valve chamber into two areas, the first area being connected to the trigger opening and the second area being connected to the fluid outlet opening, wherein the diaphragm is connected to a plunger, the plunger being pressed against the fluid opening due to a spring force and closing the fluid opening in the non-actuated state of the actuator, and opening the fluid opening by a fluid flowing through the fluid supply opening in the actuated state of the actuator. The diaphragm has at least one passage opening, through which a fluid can flow from the second area into the first area.

[0002] Such a pneumatic valve is known from DE 102019208051 B4. Among them, the diaphragm closes the fluid supply opening of the valve chamber, and the fluid outlet opening is continuously opened. The plunger actuated by a leaf spring and connected to the diaphragm protrudes through the trigger opening so that the diaphragm is pressed against the fluid supply opening in the non-actuated state. The trigger opening is closed by the diaphragm in the actuated state of the actuator, but the trigger opening is open in the non-actuated state, so that the fluid from the consumer device connected to the fluid outlet port (for example, a bladder to be filled with fluid, such as air) is discharged into the actuator chamber via the fluid outlet port, the hole in the diaphragm and the trigger opening, and is discharged into the environment from the actuator chamber via the fluid outlet opening. Therefore, this is a 3 / 2NC valve.

[0003] In the case of a similarly designed valve according to DE 10 2018 216 874 A1, during the filling operation, air must also flow continuously through both nozzle openings, whereby the volume flow is reduced compared to a single nozzle passage due to the additional flow resistance.

[0004] This pneumatic valve is used to control the flow of fluid to fill the elastic cushions in the vehicle, so as to form the seat contour. For this purpose, the elastic cushions are usually filled with air as the fluid.

[0005] Shape memory wires (SMA=shape memory alloys) are increasingly being used as actuators for such valves, the length of which is shortened when an electric current flows and thus heats up.

[0006] For the high volume flows required for some functions that depend on drive dynamics, such as pad adjustment, larger valve cross-sections and thus higher actuation and sealing forces are required. SMA actuators that can provide these functions need to be appropriately large in size, with the result that costs and space requirements increase.

[0007] For valves with high volume flows, the following options are known from the prior art:

[0008] By connecting several individual valves in parallel, the volume flow can be adjusted proportionally. However, the costs and installation space are increased accordingly.

[0009] As examples of various industrial valves, DE 4331568 C2 and DE 4331515 A1 disclose a servo solenoid valve and a pilot solenoid valve, respectively, which are actuated with an auxiliary flow and control a greater pressure or volume flow with a smaller actuation force.

[0010] US 9,080,682 B2 discloses a valve in which an SMA wire activates two pilot control valves via deflection for actuating a main valve. The deflection is guided by a sealing element, which reduces the available actuation force of the SMA wire.

[0011] EP 3078890 B1 also discloses a pilot valve actuated by an SMA wire. The SMA wire is located within the pressure range of the working port of the main valve; therefore, the associated electrical contacts must be gas-tight, which increases expense and therefore cost.

[0012] DE 102019209703 A1 discloses a pneumatic valve for a fluid bladder of a pneumatic adjustment device for a vehicle seat, the pneumatic valve comprising: a first valve chamber, which can be connected to a fluid source; a separate second valve chamber, which can be connected to the fluid bladder; a separate third valve chamber, which can be connected to the environment of the pneumatic valve; a separate fourth valve chamber, which is fluidically connected to the first valve chamber via a first fluid passage, to the second valve chamber via a second fluid passage, and to the third valve chamber via a third fluid passage; and a shut-off element, which is arranged in the fourth valve chamber and can be moved between a first position and a second position, in which the first fluid passage and the second fluid passage are open and the third fluid passage is closed, and in which the first fluid passage and the second fluid passage are closed and the third fluid passage is open.

[0013] DE 102017116841 A1 discloses a valve having a valve housing, the valve comprising a housing cover, a housing bottom and an intermediate housing arranged between the housing cover and the housing bottom, wherein the valve housing encloses a valve chamber, the valve chamber comprising a flow chamber and an actuation chamber, wherein the valve housing has at least one valve opening leading from the flow chamber to the actuation chamber, and wherein arranged in the actuation chamber are: at least one adjusting element, the at least one adjusting element being axially movable between a closing position for closing the valve opening and an opening position for opening the valve opening; a linear or strip-shaped SMA element for actuating the adjusting element in an opening direction and formed of a shape memory alloy; a reset element for moving the adjusting element in a closing direction; and a printed circuit board, wherein a central section of the SMA element is fixed to the adjusting element and an end thereof is electrically connected to the printed circuit board for applying an electric current, wherein the flow chamber and the actuation chamber are separated from each other by a partition having the valve opening in such a way that a fluid flowing through the valve is guided through the flow chamber when the adjusting element is actuated.

[0014] DE 102017125283 A1 relates to a valve system for a fuel tank, in particular a valve system for the monitored and / or controlled and / or regulated discharge or introduction of a fluid (preferably gas or air, or hydrocarbon-rich air or hydrocarbon-saturated air) into or out of the fuel tank, the valve system comprising a housing having a tank port for connecting the valve system to the fuel tank, a filter port for connecting the valve system to an activated carbon filter, and / or a filler pipe port for connecting the valve system to a filler pipe of the fuel tank, wherein the tank port and the filter port or the tank port and the filler pipe port are fluidically connected to each other via a main ventilation duct or Fluidically connectable, wherein at least one main ventilation valve having a valve element is arranged in the main ventilation duct, the valve element closes the main ventilation duct in a closed position and opens the main ventilation duct in an open position, wherein the box port or the box-side main ventilation duct and the filter port or the filter-side main ventilation duct, and / or the box port or the box-side main ventilation duct and the filling pipe port or the filling pipe-side main connecting duct are fluidly connected or fluidically connectable to each other via an auxiliary ventilation duct, wherein at least one valve group having at least one auxiliary ventilation valve is arranged in the auxiliary ventilation duct, the at least one auxiliary ventilation valve closing or opening the auxiliary ventilation duct.

[0015] DE 102018131802 A1 describes a valve for a cleaning system, the valve comprising a valve housing with a pump port and a consumer device port, and also comprising a main valve, a control valve and an electronic chamber integrated in the valve housing, wherein the control valve has a control valve input end with a control valve input chamber and a control valve output end with a control valve output chamber, wherein the control valve input end is fluidically connected to the pump port and the control valve output end is fluidically connected to the valve housing output, wherein the control valve also comprises a control valve body, an actuator with a motion transmission element, a movable valve element and a sealing element connected to the movable valve element, wherein the motion transmission element extends from the electronic chamber to the control valve body through a through hole, wherein the actuator can move the control valve into a closed position and can move the control valve into an open position, in which closed position, there is no fluid connection between the control valve input end and the control valve output end through the control valve body, and in which open position, there is a fluid connection between the control valve input end and the control valve output end through the control valve body, wherein the main valve is opened by opening the control valve and the main valve is closed by closing the control valve.

[0016] The object of the present invention is therefore to specify a compact pneumatic valve with a large nozzle cross section. The SMA actuator used for actuation is intended to be subjected to as little load as possible in terms of force and stroke. Furthermore, it is intended that the ports of the SMA actuator do not require expenditures regarding sealing.

[0017] This object is achieved by a pneumatic valve according to claim 1. Advantageous developments of the pneumatic valve are specified in the dependent claims.

[0018] Accordingly, the pneumatic valve according to the present invention is formed with a fluid supply port, a fluid outlet port and a fluid discharge opening. The pneumatic valve has a valve chamber, the valve chamber has 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 the actuator chamber of the valve, the actuator chamber having a fluid discharge opening. The pneumatic valve is also formed with an actuator, the actuator is formed with an SMA wire, an actuating element, a reset element, and a printed circuit board, the actuator is arranged in the actuator chamber, wherein a sealing element is arranged on the movable part of the actuating element, the sealing element is pressed against the trigger opening by the reset element in the non-actuated state of the actuator and opens the trigger opening in the actuated state of the actuator. The valve chamber is divided into two areas by a diaphragm, a first area is connected to the trigger opening, and a second area is connected to the fluid outlet opening, wherein the diaphragm is connected to a plunger, which is pressed against the fluid outlet opening due to a spring force and closes the fluid outlet opening in an unactuated state of the actuator, and is pushed away from the fluid outlet opening by the fluid flowing through the fluid supply opening and opens the fluid outlet opening in an actuated state of the actuator, wherein the diaphragm has at least one passage opening, through which the fluid can flow from the first area into the second area, and the cross-section of the passage opening is smaller than the cross-section of the trigger opening.

[0019] Therefore, in the unactuated state, the valve chamber of the pneumatic valve is connected to the air supply via the fluid supply port, wherein due to the passage opening in the diaphragm, the same pressure is set in both the first and second regions of the valve chamber, and therefore the diaphragm is unloaded. In the actuated state, the actuator opens the trigger opening, and therefore air can escape from the first region into the actuator chamber and from the actuator chamber to the environment. Due to the higher pressure in the second region, the plunger connected to the diaphragm is lifted off the fluid outlet opening in reaction to the spring force due to the effective area of ​​the diaphragm, so that air can flow into the connected consumer (e.g., pad) through the valve. Therefore, since the pressure of the inflowing air is used to open the valve, only a small force is required to actuate the SMA actuator. Since the cross-section of the passage opening is smaller than the cross-section of the trigger opening, the compressed air flowing into the second region cannot enter the first region quickly enough, and therefore as long as the trigger opening is open, there will be a greater pressure in the second region.

[0020] The actuating element may be designed as a leaf spring which simultaneously acts as a reset element.The non-movable end (bending section) of the actuating element may be connected to a printed circuit board and the movable end (actuating section) may be connected to an SMA wire.

[0021] The restoring element can also be realized with a helical spring, as shown, for example, in DE 10 2018 216 874 A1.

[0022] In one embodiment of the pneumatic valve, the valve chamber is formed with a cover element having a trigger opening. The cover element can be locked into the housing wall forming the valve chamber, thus forming a tight chamber that can also absorb the force of the spring.

[0023] In one embodiment of the pneumatic valve, the spring force applied to the plunger can be generated by a helical spring which is arranged between the plunger and the cover element. However, it is also conceivable to design the diaphragm as a spring element. The spring force must be dimensioned such that, on the one hand, the fluid outlet opening can be securely closed, but on the other hand, the pressure of the inflowing air is sufficient to lift the plunger away from the fluid outlet opening when the trigger opening is opened.

[0024] Advantageously, the cross section of the entire fluid line from the pressure supply up to and including the fluid supply opening is larger than the cross section of the fluid outlet opening, so that the pressure in the first region of the valve chamber substantially corresponds to the pressure of the inflowing air even when the fluid outlet opening is open.

[0025] In another embodiment of the pneumatic valve, the plunger may have a cup-shaped region in which the coil spring is mounted. Alternatively, the plunger may have a pin-shaped region around which the coil spring is arranged.

[0026] In a development of the pneumatic valve, the valve chamber has a web in the region close to the trigger opening, against which the region of the passage opening of the diaphragm is pressed by the inflowing fluid in the activated state of the actuator.

[0027] This reduces the working air flow and thus the pressure difference between the second area and the first area until a balance between the compression force and the spring force is achieved. However, even when the passage opening is present at the web, it must be structurally ensured that a minimum working air flow is maintained, which is important for a quick completion of the filling operation. This arrangement also does not consume any working air when the valve is not actuated.

[0028] Advantageously, the SMA wire and the bent section of the actuating element (eg, leaf spring) may be arranged on opposite sides of the printed circuit board.

[0029] In the development of the pneumatic valve, the diaphragm is clamped between a cover element and a cup-shaped element of the valve chamber which receives the cover element, as a result of which a simple assembly is achieved.

[0030] For a particularly good seal, the cover element can have a projection at its edge which is in contact with the diaphragm, as a result of which the diaphragm is additionally held by means of a positive fit.

[0031] The diaphragm can be connected integrally with the plunger. However, the diaphragm and the plunger can also be made of different parts connected to each other.

[0032] Advantageously, the cross section of the trigger opening is smaller than the cross section of the fluid outlet opening. In this way, the associated SMA actuator requires only a small stroke and a limited force for actuation. This is beneficial for the service life of the SMA wire (particularly the number of actuation cycles).

[0033] In another embodiment of the pneumatic valve, the effective area of ​​the diaphragm is larger than the cross section of the fluid outlet opening. This enables the main valve to open despite the high initial pressure and against the force of the spring even when the consumer is not pressurized. The pressure supply provides additional energy for the opening. The initial pressure can vary within a wide range; the magnitude of the initial pressure only needs to be such that at least the compressive force acting on the diaphragm is greater than the restoring force of the spring.

[0034] In a development of the pneumatic valve, the fluid outlet opening of the valve chamber is connected to the fluid outlet port via a further valve element. This enables a 3 / 3 valve to be realized.

[0035] If the further valve element is open in its unactuated state, the pneumatic valve is realized as a 3 / 3 NO valve.

[0036] If, on the other hand, the further valve element is closed in its unactuated state, the pneumatic valve is formed as a 3 / 3 NC valve.

[0037] The invention will be explained in more detail below based on exemplary embodiments with the aid of the accompanying drawings, in which:

[0038] Figure 1 The pneumatic valve according to the present invention is shown,

[0039] Figure 2 A detailed view of the valve chamber is shown,

[0040] Figure 3 shows the pneumatic valve in a deactivated state,

[0041] Figure 4 shows the pneumatic valve in an activated state,

[0042] Figure 5 The pneumatic valve is shown as a 3 / 3 NC valve in the exhaust state,

[0043] Figure 6 The pneumatic valve is shown as a 3 / 3 NO valve,

[0044] Figure 7 A valve chamber with a variant of a diaphragm-plunger connection is shown, and

[0045] Figure 8 A valve chamber with a variant of a spring receiving seat for a plunger is shown.

[0046] Figure 1A cross-sectional illustration of a first exemplary embodiment of a pneumatic valve is shown, which is formed with a housing 10 having a first housing part 11, which in the illustrated exemplary embodiment is designed as a base plate. The housing 10 also has a second housing part 12 designed as a cover and finally a third cup-shaped housing part 13, which is designed as an insert between the first housing part 11 and the second housing part 12 and on which a fluid supply port P and a fluid outlet port A are integrally formed. In the second housing part 12, a fluid discharge opening R is formed, which connects an actuator chamber 15 formed between the second housing part 12 and the third housing part 13 and in which an actuator 16 is arranged to the environment, so that the opening for the electrical connection of the actuator does not have to be sealed.

[0047] A valve chamber 14 is formed on the third housing portion 13 in such a manner that the third housing portion has a pot-shaped molding into which a cover element K is inserted as a cover of the valve chamber 14. The valve chamber 14 has a fluid supply opening FZ, a fluid outlet opening VH serving as a main valve, and a trigger opening VT. In the illustrated exemplary embodiment, the fluid supply opening FZ and the fluid outlet opening VH are formed in the third housing portion 13, and the trigger opening VT is formed in the cover element K that closes the valve chamber 14.

[0048] Thus, compressed air can be guided into the housing 10 via the fluid supply opening FZ (for example from a compressor), wherein the compressed air can enter the valve chamber 14 via the fluid supply opening FZ and from the valve chamber via the fluid outlet opening VH and the fluid outlet port A into a consumer device (for example an air cushion) that can be connected to the fluid outlet port.

[0049] As in Figure 2 As can be seen in detail in the figure, the elastic membrane M divides the valve chamber 14 into a first lower region 1 and an upper second region 2 illustrated in the figure. The first region 1 is connected to the fluid supply opening FZ and thus to the fluid supply port P. The second region 2 is closed airtightly relative to the actuator chamber 15 and thus relative to the environment by a cover element K. The membrane M has a small passage opening D, which allows a limited air flow (working air) from the first region 1 of the valve chamber 14 into the second region 2.

[0050] The diaphragm M is connected to the plunger S. The plunger S has a sealing surface on its lower side so as to close the nozzle seat of the fluid outlet opening VH when it is in its lower end position. The plunger S can be made of an elastic material integrally with the diaphragm M, or can be a component assembled with the plunger S. An elastic element F (e.g., a spring) attached between the cover element K and the plunger S generates a reset force to close the fluid outlet opening VH by means of the plunger S. The elastic element F can also be optionally formed by a diaphragm M, which pulls the plunger S to the lower end position closing the fluid outlet opening VH by means of its inherent stress.

[0051] The associated SMA actuator is composed of a leaf spring B and an SMA wire SMA, wherein the leaf spring B has a bending section and an actuating section, which are arranged on opposite sides of an electrical printed circuit board 17 and are under ambient pressure in an actuator chamber 15. The cover element K has a trigger opening VT, which acts as a trigger valve. A sealing element E that can seal the trigger opening VT is fastened to the underside of the actuating section of the leaf spring B.

[0052] Figures 3 to 5 The pneumatic valve is illustrated as a 3 / 3 NC valve, in which the two valve elements V1 and V2 are in three different switching states. The first valve element V1 is formed with the above-mentioned valve chamber 14, and the second valve element V2 is formed as a simple valve actuated by an SMA actuator 21 and having only one valve opening 20. The sealing element 22 arranged on the SMA actuator 21 closes the valve opening 20 in the non-actuated state and opens the valve opening in the actuated state.

[0053] exist Figure 3 The "hold" state shown (ie, the SMA actuator 16 of the first valve element V1 is not activated, see Figure 3 , right side), the trigger opening VT is closed by the sealing element E. The lower area 1 and the upper area 2 of the valve chamber 14 are connected to each other via the passage opening D, and the pressure is therefore balanced. Therefore, even if the pressure supply at the fluid supply port P is a high pressure or a variable pressure, there is no pneumatic force acting on the diaphragm M. At this time, the elastic element F designed as a coil spring pushes the plunger S connected to the diaphragm M against the nozzle seat of the fluid outlet opening VH and seals the fluid outlet opening. The force of the elastic element F is configured so that the elastic element can also apply a compressive force and a sealing force under the most unfavorable conditions (e.g., the maximum pressure of the consumer and the minimum supply pressure).

[0054] The second valve element V2 is not actuated in this state (ie, in the closed state).

[0055] At the beginning of the "raise" state, if Figure 4 As shown (ie, the SMA actuator 16 of the first valve element V1 is activated, see Figure 4, right side), the trigger opening VT is open. Preferably, although the cross section of the trigger opening VT is as small as possible, it is still significantly larger than the cross section of the passage opening D. As a result, the pressure in the second region 2 of the valve chamber 14 drops and approaches the ambient pressure. At this time, the pressure difference relative to the supply pressure in the first region 1 of the valve chamber 14 generates an upwardly directed force acting on the diaphragm M, as a result of which the plunger S opens the fluid outlet opening VH and thus opens the main valve.

[0056] Since the cross section of the trigger opening VT is small compared to the cross section of the fluid outlet opening VH, the associated SMA actuator 16 requires only a small stroke and limited force for actuation. This is beneficial for the service life of the SMA wire SMA, in particular the number of actuation cycles.

[0057] Preferably, the effective area of ​​the membrane M is significantly larger than the cross section of the fluid outlet opening VH. Thus, even when the consumer is not pressurized, the fluid outlet opening VH can be opened at the fluid outlet port A in reaction to the high initial pressure and to the force of the elastic element F. The pressure supply provides additional energy for the opening ("servo valve"). The initial pressure can vary within a wide range; the magnitude of the initial pressure only needs to be at least such that the compressive force acting on the membrane M is greater than the restoring force of the elastic element F.

[0058] Advantageously, the cross-section of the entire fluid line from the pressure supply up to and including the fluid supply opening FZ is larger than the cross-section of the fluid outlet opening VH, so that even when the fluid outlet opening VH is open, the pressure in the first region 1 of the valve chamber 14 substantially corresponds to the pressure of the pressure supply.

[0059] During the "filled" state, a limited working air flow flows from the pressure supply through the passage opening D and the open trigger opening VT into the environment. When the diaphragm M is deflected to the maximum extent, the passage opening D optionally approaches the web KS in the cover element K. This reduces the working air flow and thus also the pressure difference between the lower area 1 and the upper area 2 until an equilibrium between the compression force and the spring force is achieved.

[0060] Even when the passage opening D is at the web KS, it must be structurally ensured that a minimum working air flow is maintained, which is important for a quick completion of the filling operation. When the valve is not actuated, the arrangement also does not consume any working air.

[0061] At the end of the filling operation (ie the SMA actuator 16 of the first valve element V1 is deactivated, see Figure 3 , right side), the trigger opening VT is closed again. Via the passage opening D, the pressure between the first area 1 and the second area 2 of the valve chamber 14 is then equalized again.

[0062] The force of the elastic element F therefore also causes the fluid outlet opening VH to be closed again.

[0063] In a simple manner, the first valve element V1 can be combined with the second valve element V2 for venting the consumer in a known manner, such as Figure 5 The behavior of the depicted valve arrangement therefore corresponds to a 3 / 3 NC valve (normally closed).

[0064] In the exhaust state, the second valve element V2 is actuated via an associated SMA actuator 21 with an SMA wire and a leaf spring. Then, a sealing element 22, also fastened to the leaf spring, opens the associated nozzle seat (left side). This enables air from the consumer to flow into the environment.

[0065] Similarly, the proposed first valve element V1 can be combined with a cup valve V2' (see Figure 6 , left side). In the non-operating state (not activated), an additional cup valve V2', also with an SMA actuator according to the prior art, connects the consumer attached to the fluid outlet port A to the environment via the fluid discharge opening R. When the SMA actuator is activated, the plunger and its sealing element located on top close the nozzle seat of the exhaust valve. The behavior of the depicted valve arrangement therefore corresponds to a 3 / 3 NO valve (normally open).

[0066] The optimized valve design described below may also be used to advantage:

[0067] like Figure 7 and Figure 8 As shown, the diaphragm M can be placed flush with the sealing surface on the underside of the plunger S. This has the advantage that the plunger S is guided more accurately in its lower position and is less susceptible to possible tilting.

[0068] The cover element K can advantageously have a mechanical stop during installation (eg pressing into) in the cup of the valve chamber 14 by means of the lateral projection 23 .

[0069] Thus, the vertical position of the nozzle seat of the trigger opening VT is accurately maintained and at the same time the bead at the outer edge of the diaphragm M is clamped in a defined manner. This avoids unnecessary tolerances of the mechanical and pneumatic properties of the pneumatic valve.

[0070] In order to seal the diaphragm M relative to the cover element K, the cover element can also have a narrower annular ridge or projection KRV, which presses into the edge of the diaphragm M and thus seals the diaphragm ( Figure 7 ).

[0071] The elastic element F can be guided not only in the hollow cylindrical body SB of the plunger S, but can also alternatively be guided via a pin-shaped extension SZ of the plunger, such as Figure 8This pin-shaped extension SZ can also advantageously serve as an upper end stop for the plunger and has a corresponding recess on its top side which, in the upper position of the plunger, still allows the working air to escape from the second region 2 of the valve chamber 14 through the nozzle seat of the trigger opening VT.

[0072] Compared with currently available prior art solutions, the advantages of the above embodiments are summarized as follows:

[0073] A single SMA actuator 16 can actuate a larger valve cross section for filling by means of a servo function at low loads. This results in a longer service life of the actuator 16. In addition, no parallel-connected valves are required, as a result of which installation space and costs can be reduced.

[0074] In the non-operating position, the servo valve does not consume any working air.

[0075] Servo control works over a wide pressure range of initial pressure.

[0076] • The servo valve can be easily extended with another SMA actuator to form a 3 / 3 NC valve and a NO valve.

[0077] • The SMA actuator 16 and associated printed circuit board 17 with electronics are not located within the pressure range and therefore do not have to be sealed.

Claims

1. A pneumatic valve having a fluid supply port (P), a fluid outlet port (A) and a fluid discharge opening (R), the pneumatic valve having: a valve chamber (14) having a fluid supply opening (FZ) connected to the fluid supply port (P), a fluid outlet opening (VH) connected to the fluid outlet port (A), and a trigger opening (VT) connected to an actuator chamber (15) of the valve having the fluid discharge opening (R); An actuator (16) is formed with an SMA wire (SMA), an actuating element (B), a resetting element and a printed circuit board (17), and is arranged in the actuator chamber (15), wherein: A sealing element (E) is arranged on the actuating element (B), the sealing element being pressed against the trigger opening (VT) by the reset element in the unactuated state of the actuator (16) and opening the trigger opening (VT) in the actuated state of the actuator (16); a diaphragm (M), the diaphragm dividing the valve chamber (14) into two areas (1, 2), the first area (1) being connected to the trigger opening (VT) and the second area (2) being connected to the fluid outlet opening (VH), wherein the diaphragm (M) is connected to a plunger (S), which is pressed against the fluid outlet opening (VH) by a spring force in the unactuated state of the actuator (16) and closes the fluid outlet opening, and is pushed away from the fluid outlet opening (VH) by the fluid flowing through the fluid supply opening (FZ) and opens the fluid outlet opening (VH) in the actuated state of the actuator (16), The diaphragm (M) has at least one passage opening (D) through which fluid can flow from the first region (1) into the second region (2), and the cross section of the passage opening (D) is smaller than the cross section of the trigger opening (VT).

2. The pneumatic valve according to claim 1, wherein: The valve chamber (14) is formed with a cover element (K) having the trigger opening (VT).

3. The pneumatic valve according to claim 2, wherein: The spring force applied to the plunger (S) is generated by a coil spring (F) which is arranged between the plunger (S) and the cover element (K).

4. A pneumatic valve as claimed in any one of the preceding claims, wherein: The actuating element (B) is designed as a leaf spring having a bending section and an actuating section.

5. The pneumatic valve according to claim 4, wherein: The bending section and the actuating section of the leaf spring are respectively arranged on opposite sides of the electrical printed circuit board (17).

6. A pneumatic valve as claimed in any one of the preceding claims, wherein: The valve chamber (14) has a web (KS) in the area close to the trigger opening (VT), against which the area of ​​the passage opening (D) of the diaphragm (M) is pressed by the inflowing fluid when the actuator (16) is in the activated state.

7. The pneumatic valve according to any one of claims 2 to 6, wherein: The diaphragm (M) is clamped between the cover element (K) and a cup-shaped element (18) of the valve chamber (14) that receives the cover element (K).

8. The pneumatic valve according to claim 7, wherein: The cover element (K) has a projection (KRV) at its edge (KR) which is in contact with the membrane (M).

9. A pneumatic valve as claimed in any one of the preceding claims, wherein: The diaphragm (M) is integrally connected to the plunger (S).

10. A pneumatic valve as claimed in any preceding claim, wherein: The cross section of the trigger opening (VT) is smaller than the cross section of the fluid outlet opening (VH).

11. A pneumatic valve as claimed in any one of the preceding claims, wherein: The cross section of the fluid supply opening (FZ) is larger than the cross section of the fluid outlet opening (VH).

12. A pneumatic valve as claimed in any preceding claim, wherein: The effective area of ​​the diaphragm (M) is larger than the cross-section of the fluid outlet opening (VH).

13. A pneumatic valve as claimed in any preceding claim, wherein: The fluid outlet opening (VH) of the valve chamber (14) is connected to the fluid outlet port (A) via a second valve element (V2).

14. The pneumatic valve according to claim 13, wherein: The second valve element ( V2 ) is open in its unactuated state and the pneumatic valve is therefore a 3 / 3 NO valve.

15. The pneumatic valve according to claim 13, wherein: The second valve element ( V2 ) is closed in its unactuated state and the pneumatic valve is therefore a 3 / 3 NC valve.

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