Pneumatic valve and valve arrangement with at least one such pneumatic valve

Abstract

A pneumatic valve is described, comprising a housing (1) in which an air chamber (2) with a supply opening (3), a connecting opening (4) and an actuator opening (5) is formed, wherein an actuator (6) with a movable closing element (7) is arranged in the housing (1). The closing element (7) is formed with a plunger (11) which projects through the actuator opening (5) and whose end projecting into the air chamber is connected to a sealing element (8) for closing the supply opening (3). The actuator (6) further comprises a printed circuit board (12) arranged in the actuator chamber, an actuating element (13) arranged in the actuator chamber, and an actuator element (16) arranged in the actuator chamber.The actuator element (16) is designed to bring the actuating element (13) into a first state in a de-energized state, in which it presses the sealing element (8) against the supply opening (3) via the plunger (11), and to bring the actuating element (13) into a second state in which the sealing element (8) can open the supply opening (3). A membrane is arranged in the air chamber (2), which airtightly separates the supply opening (3) and the connecting opening (4) from the actuator opening (5).

Description

[0001] The invention relates to a pneumatic valve, comprising a housing in which an air chamber is formed with a supply opening for supplying compressed air into the air chamber, a connecting opening for connecting to a cushion to be filled with air and an actuator opening for connecting the air chamber to an actuator chamber, wherein an actuator with a movable closing element is arranged in the housing, wherein the closing element is formed with a plunger projecting through the actuator opening, the end of which projecting into the air chamber is connected to a sealing element for closing the supply opening, wherein the actuator further comprises: - a circuit board arranged in the actuator chamber, - an actuating element arranged in the actuator chamber, which has an actuating section for acting on the plunger and a bending section connected to the actuating section and the circuit board, and - an actuator element arranged in the actuator chamber, which has a first end that is mechanically connected to the actuating section, and a second end that is mechanically and electrically connected to the circuit board, wherein the actuator element is designed to bring the actuating element into a first state in which it presses the sealing element against the supply opening via the plunger, and to bring the actuating element into a second state in which the actuating section exerts no force on the plunger, so that the sealing element can release the supply opening, in a de-energized state.

[0002] Such a pneumatic valve is already described in the (unpublished) DE 10 2023 203 271.6. There, the area between the sealing element and a cover of the air chamber, in which the actuator opening is located and through which the plunger protrudes, is sealed by a dome-shaped seal. However, this seal only closes the actuator opening due to residual stress when the valve is not actuated, resulting in only limited sealing. Furthermore, a force must be applied to counteract this residual stress when opening the valve. This is achieved by an additional spring that pushes the sealing element away from the supply opening.

[0003] Such electrically controlled pneumatic valves are used in vehicles to control the filling of fillable, elastic cushions that shape seat contours. The elastic cushions are typically filled with air. Shape memory wire (SMA = shape memory alloy) is increasingly being used as an actuator for such valves. This wire shortens in length when current flows and the resulting heating occurs.

[0004] For existing valves with SMA actuators, there are basically two options for positioning the SMA element: The first group consists of a complete separation between the fluid and the SMA element. This is particularly necessary (but not exclusively) in hydraulic systems to prevent the SMA element from being exposed to the strong cooling effect of the fluid.

[0005] In the subject matter of EP 2 239 486 A1, this separation is effected by means of a sliding sealing ring, while in the subject matter of WO 2014 / 135 909 A1, this separation is effected by means of an elastic membrane.

[0006] The disadvantage here is the additional actuating force required by the actuator. In the case of a sealing ring, this is due to the friction of the sealing ring. In the case of a diaphragm, the effective pressure area of ​​the diaphragm is significantly larger than the actual nozzle opening, which increases the required force and thus the size and / or cost of the actuator.

[0007] A second group uses an SMA element located within a pressure chamber through which fluid flows. In DE 10 2005 060 217 B4, this is connected to a working connection. When the SMA actuators are activated, this pressure chamber is then connected either to a supply pressure or to exhaust air. Alternatively, the pressure chamber containing the SMA element is permanently connected to the supply pressure. In both cases, the entire installation space containing the SMA element must be sealed from the environment. This requires an appropriate seal (elastomer, adhesive, or similar) as well as means to absorb the resulting pressure forces (e.g., screwing, welding, etc.). Likewise, costs are incurred for contacting the circuit board (or its area) in the pressure chamber from outside (e.g., via airtight feedthrough contacts, increased number of circuit board layers, or similar).All of this increases the required installation space and the cost of the valve.

[0008] Furthermore, DE 10 2018 216 874 A1 and DE 10 2019 208 051 A1 show an SMA valve in which the SMA wire is arranged outside the pressure area and actuates the valve element by pushing it through a vent valve via a plunger.

[0009] Similarly, CN 112066032 A shows an SMA valve with a pulling action of the valve element by a rod penetrating the vent valve. CN 112066040 A alternatively shows a cap that seals the rod and the valve element from the housing opening, so that the SMA element remains outside the pressure area, but no air can escape through the opening for the plunger.

[0010] DE 10 2023 211 886.6, which was also not pre-published, shows a pot valve with a diaphragm for pressure-assisted opening, whereby the pressure difference between a valve chamber and the environment generates a significant force in the direction of opening the valve.

[0011] The object of the invention is therefore to provide a pneumatic valve with a cost-effective and compact SMA actuator. A circuit board electrically and mechanically connected to the SMA element should be located entirely in a location connected to the ambient pressure. At the same time, the air flow through the valve should be completely sealed from the environment, and the pressure within the valve chamber should exert as little force as possible on a sealing element.

[0012] The object is achieved in a generic pneumatic valve in that a membrane is arranged in the air chamber, which membrane has the shape of at least one double cone in a first section, which has the largest diameter in its center and is arranged around the tappet, and which is connected hermetically with the sealing element at its first end facing the supply opening and is integrally connected with a membrane plate at its other end, the outer edge of which is connected hermetically with the housing wall of the air chamber.

[0013] The SMA actuator actuates the valve through an actuating opening using a plunger. The plunger's sealing element is integrally connected to a diaphragm; alternatively, the diaphragm is hermetically connected to the plunger (e.g., clamped or glued). The diaphragm is hermetically connected at its outer edge to the valve chamber and its cover (e.g., clamped), thus sealing the air chamber from the environment.

[0014] The diaphragm is preferably rotationally symmetrical and contains at least one bulge in the form of a double cone; the geometry of the double cone should be shaped so that the pressure forces from the air chamber exert two opposing force components on the tappet connected to the diaphragm: A force acting on the side walls of the diaphragm, parallel to the tappet axis, compresses the double cone and causes a force on the tappet in the opening direction.

[0015] A radial force direction pushes the double cone in the direction of the tappet axis, thereby causing the double cone to spread and thus a force on the tappet in the closing direction.

[0016] Both force components are of similar magnitude, particularly when the valve is not actuated (i.e. closed), so that they largely cancel each other out and the pressure difference across the double cone does not exert any relevant force on the tappet.

[0017] In an advantageous further development of the pneumatic valve, the membrane is formed integrally with the sealing element.

[0018] Alternatively, its first end can be inserted into a cup-shaped receiving opening of the sealing element, thereby forming a cup-shaped receptacle for the plunger. It is essential that the connection between the diaphragm and the sealing element is airtight, thus preventing pressure in the air chamber from escaping through the actuator opening.

[0019] In an advantageous design of the pneumatic valve, the outer edge of the diaphragm plate is clamped between two housing parts. This is intended to create an airtight connection. Alternatively or additionally, the outer edge of the diaphragm plate can also be glued to the housing wall.

[0020] In an advantageous development of the pneumatic valve, the side walls of the double-cone-shaped first section of the membrane have a greater thickness than its kinks.

[0021] The angle between the two side walls of the double cone can preferably have an angle of 60 degrees to 120 degrees, preferably 90 degrees.

[0022] The plunger can be composed of an elastic part and a non-elastic pin. The elastic part of the plunger can be formed integrally with the diaphragm. Elastomers such as EPDM or silicone can be used as the material for the diaphragm.

[0023] The upper surface of the diaphragm preferably rests firmly against the cover of the valve chamber. This means that the pressure difference between the valve chamber and the surroundings only acts on the comparatively small area of ​​the passage opening for the tappet, generating only a limited force in the direction of valve opening. This ensures that, especially when the valve is closed, the actuator's restoring force acts as a sealing force on the valve seat to the greatest possible extent.

[0024] The area of ​​the sealing seat and the area of ​​the passage opening for the tappet are preferably the same (or similar) in size. This means that the pressure force on the tappet depends essentially only on the upstream pressure and not on the pressure in the valve chamber. To support this property, it may be necessary for the diaphragm or the double cone to have different material thicknesses and thus different stiffnesses. This allows the surfaces of the double cone to be thicker and thus more dimensionally stable. The joints or bends of the double cone and the diaphragm are comparatively thinner, thus allowing the diaphragm to move as desired.

[0025] The invention also relates to a valve arrangement with two pneumatic valves as described above. The supply port of a first valve is connected to a compressed air connection of the valve arrangement, the connection port of the first valve is connected to an air cushion connection of the valve arrangement, and the supply port of a second valve is connected to the air cushion connection of the valve arrangement, and the connection port of the second valve is connected to an ambient connection of the valve arrangement.

[0026] The invention will be described in more detail below using exemplary embodiments with the aid of figures. Fig. 1 shows a first embodiment of a pneumatic valve according to the invention in the unactuated state, Fig. 2 the first design variant of the valve in the actuated state during a filling process, Fig. 3 a detailed view of the air chamber with an airtight membrane in the unactuated state, Fig. 4 a detailed view of the air chamber with an airtight membrane in the actuated state, Fig. 5 a double-conical membrane with a one-piece sealing element showing the forces acting on the side walls of the membrane, Fig. 6 an alternative design of the membrane, Fig. 7 another alternative design of the membrane, with a sealing element that is not integrally formed and Fig. 8 an embodiment of a valve arrangement.

[0027] Fig. 1 shows a pneumatic valve in a cross-sectional view, which is formed with a housing 1 having a first housing part 17, which in the illustrated embodiment is designed as a base plate. The housing 1 also has a second housing part 18, which is designed as a cover, and finally a third cup-shaped housing part 19, which is designed as an insert between the first and second housing parts 17, 18 and onto which a supply connection 27 and a connection connection 28 are formed. An actuator chamber, in which an actuator 6 is installed, is formed between the third housing part 19 and the second housing part 18.

[0028] An air chamber 2 is formed on the third housing part 19 by having a cup-shaped portion into which a closure piece 2a is inserted as the cover of the air chamber 2. The connection between the cup-shaped portion and the closure piece 2a is established, for example, by means of a press fit or a projection 2b on the closure piece 2a, which engages in a groove in the cup-shaped portion. It can be advantageous if the pressure and sealing forces are absorbed by such clipping, screwing, etc.

[0029] The air chamber 2 has a supply opening 3, a connection opening 4, and an actuator opening 5. In the illustrated embodiment, the supply opening 3 and the connection opening 4 are formed in the third housing part 19, and the actuator opening 5 is formed in the end part 2a that closes off the air chamber 2. Compressed air can therefore be fed into the housing 1 via the supply connection 27, for example from a compressor, whereby the compressed air can reach the air chamber 2 via the supply opening 3 and from there via the connection opening 4 and the connection connection 28 into an air cushion that can be connected to it. On the other hand, compressed air from the air cushion can reach the air chamber 2 via the connection connection 28 and the connection opening 4 and from there back to the supply opening, and be released if no higher pressure prevails there.

[0030] In the air chamber 2, a closing element 7 is formed with a plunger 11, at the end of which protrudes into the air chamber 2 a sealing element 8 is arranged or formed thereon.

[0031] A diaphragm 30 is arranged in the air chamber 2 and, with a first part around the tappet 11, forms a double cone 30a, which has its largest diameter approximately at its center. It would also be possible to provide two or more such double cones as a type of bellows. A diaphragm plate 30b is molded onto the double cone 30a as a second diaphragm part or is connected to it in an airtight manner. The diaphragm plate 30b is clamped or glued, or both, between the cup-shaped molding and the end part 2a. The diaphragm 30 thus seals the actuator opening 5, so that the pressure in the air chamber 2 cannot equalize in the actuator chamber defined by the housing parts 18 and 19. This prevents air in an air cushion connected to the connecting port 28 from escaping via the actuator opening 5, neither when the valve is actuated nor when it is not actuated.

[0032] The first part of the diaphragm 30, designed as a double cone 30a, is provided with an inner bore for the tappet 11. The air chamber 2 with the openings 3, 4, 5 is in the Fig. 3 shown in an enlarged view.

[0033] An actuator 6 is also arranged in the housing 1. The actuator 6 is formed with a circuit board 12, which is mounted and mechanically connected to corresponding struts of the third housing part 19. Connected to the circuit board 12 is an actuating element 13, which has an actuating section 14 that is in direct contact with the plunger 11 and has a bending section 15 that is connected to the circuit board 12.

[0034] The actuator 6 further comprises an actuator element 16, which is preferably formed with a wire made of a shape memory alloy that shortens when subjected to current supplied by a circuit (not shown) on the circuit board 12. In the non-activated state, the actuating element 13 is preloaded such that the actuating element 13 presses with its actuating section 14 against the plunger 11 and thus presses the sealing element 8 against the supply opening 3, whereby the actuator opening 5 is opened but sealed by the membrane 30.

[0035] The actuator element 16 is connected - for example by means of crimp connections - both to the actuating element 13 and to the circuit board 12.

[0036] Advantageously, the actuator element 16 is formed above a top side 20 of the circuit board 12, and the actuating element 13 is formed below a bottom side 21 of the circuit board 12, resulting in a very compact design. In principle, the design can also be mirror-inverted, so that the actuator element 16 is located below the circuit board 12 and the actuating element 13 is located above the circuit board 12.

[0037] Advantageously, an end position detection element 26 is formed on the actuating element 13, which comes into contact with the circuit board 12 when the actuator 6 is actuated and enables a current flow, whereby it is detected that the end position has been reached, so that the current through the actuator element 16 can be switched off or at least reduced in order not to overload it.

[0038] In the Fig. 2 is the valve of the Fig. 1 in a second, activated state, i.e. in a state in which the supply opening 3 is open and air can flow from the supply connection 27 via the connecting connection 28 through the air chamber 2 into a connected air cushion.

[0039] In the Fig. 2, the same parts are provided with the same reference numerals as in Fig. 1, where for reasons of clarity only the essential reference symbols are shown.

[0040] By activating the actuator 6, the actuating element 13 is raised, thus pushing the closing element 7 upwards due to a higher air pressure in the air chamber 2, which is generated by compressed air at the supply connection 27, and consequently compressing the double cone 30a of the diaphragm 30. The closing element 7 no longer presses on the sealing element 8, so that the latter is raised by the air pressure and releases the supply opening 3.

[0041] In the Fig. Figure 4 is an enlarged view of the air chamber 2 with the openings 3, 4, 5 and the membrane 30 of a pneumatic valve in the open state, corresponding to the Fig. 2. Here, too, the same parts as in the Fig. 1 to 3 are provided with the same reference numerals.

[0042] The Fig. Figure 5 shows, indicated by arrows 31, the forces exerted on the side walls of the double cone 30a of the first part of the membrane 30 due to the air pressure in the air chamber 2. Since in the illustrated embodiment the Fig. 5 the angle between the two side walls is approximately 90 degrees, the forces in the direction of the axis of a tappet 11 as well as in the radial direction approximately cancel each other out, so that this form of a double cone is relaxed.

[0043] In the Fig. 6 indicates that the side walls of the double cone 30a are thicker than the kinks 30c, so that the forces are distributed differently. In this way, the tension of the membrane 30 can be adjusted.

[0044] In the Fig. Finally, Figure 7 indicates that the membrane 30' does not necessarily have to be formed integrally with a sealing element 8'. There, the sealing element 8' has a recess into which a cup-shaped bulge of the membrane 30' is pressed or glued by means of the tappet 11.

[0045] The Fig. 8 shows a valve arrangement with two pneumatic valves as shown in the Fig. 3 and Fig.4. The supply port 3 of a first valve V1 is connected to a compressed air connection P of the valve arrangement, and the connection port 4 of the first valve V1 is connected to an air cushion connection A of the valve arrangement. The supply port 3' of a second valve V2 is connected to the air cushion connection A, and the connection port 4' of the second valve is connected to an ambient connection R of the valve arrangement.

[0046] With this connection of the two 2 / 2-NC valves, a 3 / 3-NC valve is realized.

[0047] The pneumatic valve according to the invention results in increased flexibility of possible valve circuits with SMA actuator by providing a 2 / 2 valve in addition to 3 / 2 valves according to the state of the art.

[0048] There is also increased tightness to the environment (against negative leakage) due to the one-piece or pressed diaphragm to the tappet and the valve chamber.

[0049] This results in increased tightness against the pre-pressure (against positive leakage) through optimal use of the actuator return force as a sealing force.

[0050] It is advantageous to avoid air loss and associated flow noise during (slow) switching of the upstream pressure valve in a 3 / 3 valve arrangement. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 203 271.6

[0002] EP 2 239 486 A1

[0005] WO 2014 / 135 909 A1

[0005] DE 10 2005 060 217 B4

[0007] OF 10 2018 216 874 A1

[0008] OF 10 2019 208 051 A1

[0008] CN 112066032 A

[0009] CN 112066040 A

[0009] FROM 10 2023 211 886.6

[0010]

Claims

[1] Pneumatic valve, with a housing (1) in which an air chamber (2) is formed with a supply opening (3) for supplying compressed air into the air chamber (2), a connection opening (4) for connection to a cushion to be filled with air and an actuator opening (5) for connecting the air chamber (2) to an actuator chamber, wherein an actuator (6) with a movable closing element (7) is arranged in the housing (1), wherein the closing element (7) is formed with a plunger (11) projecting through the actuator opening (5), the end of which projecting into the air chamber is connected to a sealing element (8) for closing the supply opening (3), wherein the actuator (6) further comprises: - a circuit board (12) arranged in the actuator chamber, - an actuating element (13) arranged in the actuator chamber, which has an actuating section (14) for acting on the plunger (11) and a bending section (15) connected to the actuating section (14) and the circuit board (12), and - an actuator element (16) arranged in the actuator chamber, which has a first end mechanically connected to the actuating section (14) and a second end mechanically and electrically connected to the circuit board (12), wherein the actuator element (16) is designed to bring the actuating element (13) into a first state in which it presses the sealing element (8) against the supply opening (3) via the tappet (11) in a de-energized state, and to bring the actuating element (13) into a second state in which the actuating section (14) exerts no force on the tappet (11), so that the sealing element (8) can release the supply opening (3), characterized by , that a membrane is arranged in the air chamber (2), which in a first section has the shape of at least one double cone, which has the largest diameter in its center and is arranged around the tappet (11), and which is connected with its first end facing the feed opening (3) in an airtight manner to the sealing element (8) and with its other end in one piece to a membrane plate, the outer edge of which is connected with the housing wall of the air chamber (2) in an airtight manner. [2] Pneumatic valve according to claim 1, characterized by that the membrane is formed integrally with the sealing element (8). [3] Pneumatic valve according to claim 1, characterized by that the membrane is inserted with its first end into a cup-shaped receiving opening of the sealing element (8) and thereby forms a cup-shaped receptacle for the tappet (11). [4] Pneumatic valve according to one of claims 1 to 3, characterized by that the outer edge of the membrane plate is clamped between two housing parts. [5] Pneumatic valve according to one of claims 1 to 4, characterized by that the outer edge of the membrane plate is glued to the housing wall. [6] Pneumatic valve according to one of claims 1 to 5, characterized by that the side walls of the double-cone-shaped first section of the membrane have a greater thickness than its kinks. [7] Pneumatic valve according to one of claims 1 to 6, characterized bythat the angle between the two side walls of the double cone is between 60 degrees and 120 degrees, preferably 90 degrees. [8] Pneumatic valve according to one of claims 1 to 7, characterized by that the plunger is composed of an elastic part and a non-elastic pin. [9] Pneumatic valve according to claim 7, characterized by that the elastic part of the tappet is formed integrally with the membrane. [10] Valve arrangement with two pneumatic valves according to one of claims 1 to 9, in which the supply opening (3) of a first valve (V2) is connected to a compressed air connection (P) of the valve arrangement and the connecting opening (4) of the first valve (V2) is connected to an air cushion connection (A) of the valve arrangement and the supply opening (3) of a second valve (V1) is connected to the air cushion connection (A) of the valve arrangement and the connecting opening (4) of the second valve (V1) is connected to an ambient connection (R) of the valve arrangement.

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