EP2028377B1 - Membrane actuator and method for manufacturing a membrane actuator - Google Patents

Description

The invention relates to a diaphragm actuator for a valve stem, comprising a housing, a diaphragm which is sealed to the housing with its radially outer portion and provides a chamber in the housing and a diaphragm plate against which the diaphragm is supported. The invention also relates to a method for producing a membrane drive.

Such pneumatic or hydraulic drive units are used to generate strokes of actuators, in particular of valves, for throttling flowing media. The membrane drives are usually simple and robust and are characterized by high realizable speeds. In this case, a control diaphragm is used in a lower housing part, which divides the housing interior into two chambers. In one chamber, the control medium, for example, under positive or negative pressure air introduced, whereby the position of the diaphragm is changed against the force of a return spring. The lower housing part is closed with an upper housing part, which takes place either by a flanging of the edge of one housing part to the edge of the other housing part or by means of a screw, for which the two housing parts must have flanges. Both in the crimping as well as the screwing the membrane is held at its radially outer edge of the edges of the two housing parts. This structure has proven itself many times, but it has the use of such membrane drives in clean rooms or production facilities in the food industry or biochemistry the major disadvantage that germs can settle on the flange or flange. In addition, the outer dimensions of such diaphragm drives are relatively large.

From the US 1,885,457 A a diaphragm drive is known, in which the membrane is thickened on its outer circumference and fixed to the inside of a sleeve. In this case, the membrane protrudes in the axial direction on both sides over the sleeve, but is permanently radially inside the sleeve. To attach the membrane tightly in the housing, it requires shoulder-shaped housing heels that overlap these projecting parts of the membrane. In addition, the distance between these shoulder-shaped housing heels must be matched to the dimension, ie the thickness of the membrane in the region of the projecting parts, so that it is slightly compressed. However, the housing heels require a flange for connecting the two housing parts, so that the membrane drive is unsuitable for clean rooms.

From the US 2,664,673 A is also known a vulcanized into a sleeve membrane. The DE 39 01 900 A1 shows an actuator with two membranes, the thickened ends are inserted in intermediate rings and receptacles in the housing.

The invention is therefore based on the object to provide a membrane drive, which can also be used in critical environments, especially in clean rooms, which also has smaller dimensions with the same power and is easy to manufacture.

This object is achieved with a diaphragm drive having the features of claim 1.

The essential aspect of the invention is that the radially outer region of the membrane no longer protrudes in the radial direction, but in that it rests against a sleeve and extends in the axial direction. The sleeve now serves as a connecting means, via which the membrane is connected to the housing. Since the edge region of the membrane no longer extends in the radial direction, this no longer requires the usual clamping space, for example the flange or the flange.

The housing parts can be put together bluntly. As a result, the outer diameter of the membrane drive decreases in a consistently large interior, on the other hand, a smooth outside can be created, where no germs can set or which can be relatively easily decontaminated.

According to the invention, the outer edge region of the membrane can be fastened to the inside of the sleeve or else to the outside of the sleeve. The sleeve clamps the membrane to the inside of the housing base.

With preference, the radially outer part of the membrane to the sleeve, in particular to the inside of the sleeve, vulcanized, glued or welded. As a result, a tight connection of membrane and sleeve is provided in a relatively simple manner.

If the membrane consists of a plastic, in particular an elastomer, which can also be reinforced by a woven fabric, then the vulcanization or bonding of the membrane and the sleeve is suitable, whereas if the membrane is made of a stainless steel foil, the welding is suitable, provided the sleeve is also made of metal.

In a further development of the invention it is provided that the radially outer edge of the membrane is designed as a sealing lip, which projects beyond the sleeve in the axial direction and radially outward. In this way, the edge of the membrane designed as a sealing lip bears against the inner circumferential surface of the lower housing part under prestressing and seals the chamber formed there from the outer side. With a smooth inner circumferential surface of the housing lower part, which is the case in particular with deep-drawn parts, no further sealing is required.

Advantageously, the sealing lip protrudes in the direction of the bottom of the housing. If a pressure is built up in the chamber formed there, the contact pressure of the sealing lip on the inner circumferential surface of the housing underside increases, whereby the seal is reinforced.

In one embodiment, it is provided that the sleeve is used without play in the housing lower part, in particular is pressed into this. For this purpose, a special press-in device is used, which pushes the sleeve with attached membrane deformation-free in the housing base. In this case, the sleeve advantageously projects beyond the lower housing part, so that the projecting portion of the sleeve forms a guide for the upper housing part. The sleeve thus extends over the two edges of the upper housing part and lower housing part. The upper housing part and the lower housing part can be flush with each other with their outer surfaces, which has the significant advantage that no germs can accumulate in this area. In addition, the outer diameter of the diaphragm drive, as already mentioned, is not unnecessarily increased.

According to the invention, the lower housing part is welded to the upper housing part. In this case, the housing made of metal, in particular stainless steel, or plastic. The sleeve may be made of metal, in particular stainless steel, or plastic. If the two housing parts are welded together, the existing shell of the same material in the same welding process can be welded to the housing.

The object mentioned above is also achieved by a method which has the features of claim 10. This method has the significant advantage that due to the modular design of the membrane drive, the assembly is simple and machine feasible, and the membrane can be used exactly in the lower housing part, since they are on the sleeve can be gripped and placed free of play in the housing. The return spring can be arranged in the lower housing part or in the upper housing part, depending on whether the membrane terminates a vacuum or overpressure chamber. In this case, in order to achieve a tight connection of the membrane and sleeve, the membrane is vulcanized to the inside or outside of the sleeve, glued or welded. The type of connection is determined by the materials of the membrane and the sleeve. In addition, the sleeve is connected to the membrane in such a way that the radially outer edge of the membrane protrudes beyond the sleeve in the axial and radial directions, so that this edge bears in the form of a sealing lip on the inside of the housing lower part in a sealing and prestressing manner.

An exact positioning of the membrane within the housing is achieved in that the sleeve is pressed into the housing lower part. For this purpose, for example, a suitable pressing device is used with which certain Einpresstiefen are adjustable. In particular, at low Einspresskräften the sleeve is welded to secure the position with the housing. This can be done according to the invention in that after insertion of the sleeve in the lower housing part, the upper housing part is pushed onto the protruding upper edge of the sleeve and the sleeve is welded during welding of the upper housing part and lower housing part. These components, as already mentioned, made of plastic or stainless steel.

Very smooth outer surfaces of the upper housing part and lower housing part can be produced by these components are produced by deep drawing. As a result, very small wall thicknesses can be realized, so that on the one hand with the same drive power small outer diameter can be generated, on the other smooth surfaces are present, which can be kept relatively germ-free or decontaminated.

In a variant, it is provided that the radially outer edge of the membrane is thickened or bead-shaped.

The essential aspect of this variant is that the radially outer region of the membrane no longer protrudes in the radial direction, but in that it rests on a sleeve, extending in the axial direction. The sleeve now serves as a connecting means, via which the membrane is connected to the housing. Since the edge region of the membrane no longer extends in the axial direction, this no longer requires the usual clamping space, for example the flange or the flange. The housing parts can be put together bluntly. As a result, the outer diameter of the membrane drive decreases in a consistently large interior, on the other hand, a smooth outside can be created, where no germs can set or which can be relatively easily decontaminated. In addition, the thickened or bead-shaped edge of the membrane, which is preferably O-ring-shaped, under prestress against the inner peripheral surface of the housing lower part and seals the chamber formed there from the other chamber. With a smooth inner circumferential surface of the housing lower part, which is the case in particular with deep-drawn parts, no further sealing is required. If a pressure is applied in the chamber formed there, the contact pressure of the edge on the inner peripheral surface of the housing underside increases, whereby the seal is reinforced.

Advantageously, on the inside of the radially outer edge of the membrane, a clamping ring or a clamping sleeve. In this case, the radially outer region of the membrane between the inside of the sleeve and the clamping ring or the clamping sleeve is clamped or clamped. The edge of the membrane is thereby guided exactly and pressed against the inner peripheral surface of the housing bottom. An assembly is greatly simplified and accelerated because a bonding of the edge region of the membrane with the inside of the sleeve can be omitted.

An optimal fixation of the clamping ring or the clamping sleeve at the edge of the membrane is effected in that the clamping ring or the clamping sleeve on the side facing the edge has a circumferential groove or bead, which serves to partially receive the edge.

The clamping ring or the clamping sleeve has a substantially S-shaped cross-sectional shape and the radially outer edge of the membrane is partially under attack. In this way, the exact positioning of the edge of the membrane is ensured at the bottom of the sleeve.

Preferably, the clamping ring or the clamping sleeve made of metal, in particular stainless steel, so that the required holding forces can be ensured over a long period. The clamping ring or the clamping sleeve may also be made of plastic, if the membrane drive, for example. used in aggressive environments or aggressive media.

Further advantages, features and details of the invention will become apparent from the dependent claims and the following description in which with reference to the drawings particularly preferred embodiments are described in detail. The features shown in the drawing and mentioned in the description and in the claims may each be essential to the invention individually or in any combination.

Figur 1

einen Längsschnitt durch eine perspektivische Darstellung eines Ausführungsbeispiels des erfindungsgemäßen Membranantriebs mit in Ruhelage sich befindender Membran;

Figur 2

einen Schnitt durch die Membran mit befestigter Hülse;

Figur 3

eine vergrößerte Wiedergabe des Ausschnitts III gemäß Figur 2;

Figur 4

einen Längsschnitt durch eine perspektivische Darstellung eines Ausführungsbeispiels des erfindungsgemäßen Membranantriebs mit in Ruhelage sich befindender Membran; und

Figur 5

eine vergrößerte Wiedergabe des Ausschnitts V gemäß Figur 4.

In the drawing show:

FIG. 1

a longitudinal section through a perspective view of an embodiment of the membrane drive according to the invention with in-rest position befindendem membrane;

FIG. 2

a section through the membrane with attached sleeve;

FIG. 3

an enlarged view of the section III according to FIG. 2 ;

FIG. 4

a longitudinal section through a perspective view of an embodiment of the membrane drive according to the invention with in-rest position befindendem membrane; and

FIG. 5

an enlarged view of the section V according to FIG. 4 ,

In the FIG. 1 is denoted by the reference numeral 10, a diaphragm drive, with which a valve spindle 12 is moved in the direction of the double arrow 14. The diaphragm drive 10 has a housing 20 consisting of an upper housing part 16 and a lower housing part 18, in which a membrane 22 divides the housing interior into a first chamber 24 and a second chamber 26. In the second chamber 26, a spring assembly 28 is arranged, which holds the diaphragm 22 in a basic position via a diaphragm plate 30. The membrane 22 abuts against this diaphragm plate 30 and consists of an elastic material, for example a stainless steel foil or a fabric-reinforced elastomer, so that it can bend and roll in the region 32.

The first chamber 24 has an outwardly leading port 34 over which the first chamber has a control medium, e.g. Control air (compressed air) is supplied. By increasing the pressure in the first chamber 24, the diaphragm plate 30 is raised against the force of the spring assembly 28, whereby the valve spindle 12 is retracted into the housing 20.

The membrane 22 has a radially outer region 36 which rests against the inside of a sleeve 38. This sleeve 38 is pressed by means of a suitable pressing device in the lower housing part 18 such that it projects beyond the upper side of the housing lower part 18 with an upper portion 40. The projection of the section 40 is adjusted by means of a corresponding stop on the press-in device.

The Einpresstiefe can also be adjusted by the fact that by partial expansion of the sleeve, the upper edge of the sleeve, as in FIG. 4 shown, is slightly bent or issued radially outward, and that the inner sides of the housing top 16 and the housing base 18 are chamfered so that the flared edge can sit partially on the chamfer. The sleeve 38 is thus inserted so far until the edge abuts against the chamfer of the housing lower part 18. When mounted upper housing part 16, the lower edge is also chamfered radially inside, also the sleeve 38 is fixed positively against displacement.

The section 40 serves as a guide for the upper housing part 16 when placed on the lower housing part 18. In addition, in FIG. 1 recognizable that the upper housing part 16 is seated flush on the upper housing part 18, so that the outer surfaces are in alignment with each other. After joining the components, in particular after placing the upper housing part 16 on the lower housing part 18, in particular by means of a laser beam, the upper housing part 16, the lower housing part 18 and the sleeve 38 are welded together, which is indicated by a weld 42. This weld 42 penetrates the housing 20 and penetrates into the sleeve 38, so that the upper housing part 16, the lower housing part 18 and the sleeve 38 are integrally connected to one another.

Out FIG. 1 is still clearly visible that the radially outer edge 44 of the membrane 22 is formed as a sealing lip 46 which bears against the inner surface 48 of the lower housing part 18 sealingly and under prestress.

The FIG. 2 shows a section through the membrane 22 with attached sleeve 38, wherein the membrane 22 has a shoulder 50 for receiving the lower end of the sleeve 38. A fixation of sleeve 38 and membrane 22 is achieved in that the membrane 22 is vulcanized to the inner surface of the sleeve 38. In the enlarged section III according to FIG. 3 is clearly the shoulder 50 recognizable and can also be seen that the sealing lip 46 in the radial direction by the amount 52 and in the axial direction by the amount 54, the sleeve 38 surmounted, ie over the dimensions of the sleeve 38 protrudes. The sealing lip 46 has a rounded sealing edge 56 and a recess 58 forms a joint for the sealing lip 46.

It can be clearly seen that the two housing parts 16 and 18 can be manufactured as deep-drawn parts with a small thickness. In addition, it can be seen that the membrane 22 is brought up to the inner surface of the housing 20 and therefore can apply the same driving forces, such as a membrane of the same diameter in conventional drives. However, the diaphragm drive 10 according to the invention has a smaller wall thickness, which is why the outer dimensions are smaller. In addition, it can be clearly seen that the membrane drive 10 according to the invention has a smooth outer surface, so that it can be kept germ-free without problems or simply cleaned. The use in sterile rooms or in aseptic areas is therefore possible.

The FIG. 5 shows an enlarged view of the section V according to FIG. 4 through the membrane 22 with attached sleeve 38, wherein the membrane 22 has a shoulder 50 for receiving the lower end of the sleeve 38. A fixation of sleeve 38 and membrane 22 is achieved in that the membrane 22 is pressed against the inner surface of the sleeve 38. For this purpose, a clamping ring 60 or a clamping sleeve is used. This clamping ring 60 includes the radial inner side of the O-ring-shaped edge 44 as well It is clearly seen that the clamping ring 60 has a western S-shaped cross-section and has a bead 62 which serves to partially receive the edge 44. As a result, an exact positioning of the clamping ring 60 is ensured at the edge 44 of the membrane 22. In addition, the diameter of the clamping ring 60 is dimensioned so that the radially outer portion 36 of the membrane 22 between the sleeve 38 and the clamping ring 60 is clamped. The upper, inwardly drawn edge 64 allows easy insertion of the clamping ring 60 in the downwardly curved radially outer portion 36 of the membrane 22nd

When inserting or inserting the sleeve 38 and the clamping ring 60 clamped membrane 22 in the upper housing part 18, the edge 44 is deformed and displaced the upper housing part 18 cutting part 66 of the rim 44 and squeezed between the upper housing part 18 and the clamping ring 60 and forms an optimal Poetry.

It can be clearly seen that the two housing parts 16 and 18 can be manufactured as deep-drawn parts with a small thickness. In addition, it can be seen that the membrane 22 is brought up to the inner surface of the housing 20 and therefore can apply the same driving forces, such as a membrane of the same diameter in conventional drives. However, the diaphragm drive 10 according to the invention has a smaller wall thickness, which is why the outer dimensions are smaller. In addition, it can be clearly seen that the membrane drive 10 according to the invention has a smooth outer surface, so that it can be kept germ-free without problems or simply cleaned. The use in sterile rooms or in aseptic areas is therefore possible. Finally, the membrane drive 10 can be mounted quickly since the membrane 22 does not have to be glued.

Claims (13)

1. A membrane actuator (10) for driving a valve spindle (12), having a housing (20), having a membrane (22) which with its radially outer region (32) is tightly joined to the housing (20) and in the housing (20) creates a chamber (24), having a membrane plate (30) against which the membrane (22) is braced, the radially outer region (32) of the membrane (22) resting on the outside or inside of a sleeve (38) and the sleeve (38) being fixed tightly in the housing (20), characterized in that the radially outer edge (44) of the membrane (22) is embodied as a sealing lip (46) or in thickened or beadlike form, in particular in O-ring form, and the sleeve (38) protrudes in the axial direction and radially outward.
2. The membrane actuator as defined by claim 1, characterized in that the radially outer region (32) of the membrane (22) is vulcanized, glued, or welded onto the inside of the sleeve (38) or rests on the inside of the sleeve (38) and is pressed against it.
3. The membrane actuator as defined by one of the foregoing claims, characterized in that the membrane (22) comprises a plastic, in particular an elastomer, preferably a woven-fiber-reinforced elastomer, or metal, in particular a special steel foil.
4. The membrane actuator as defined by one of the foregoing claims, characterized in that the sealing lip (46) protrudes in the direction toward the bottom of the housing (20).
5. The membrane actuator as defined by one of the foregoing claims, characterized in that the sleeve (38) is inserted, for instance press-fitted, into a lower housing part (18), and in particular protrudes upward past the lower housing part (18), and optionally the portion (40) of the sleeve (38) that protrudes past the lower housing part (18) forms a guide for the upper housing part (16).
6. The membrane actuator as defined by claim 5, characterized in that the lower housing part (18) and the upper housing part (16) merge in alignment with one another at their outer faces, and in particular the lower housing part (18), the upper housing part (16) and/or the sleeve (38) are welded to one another.
7. The membrane actuator as defined by one of the foregoing claims, characterized in that the chamber (24) is an underpressure or an overpressure chamber.
8. The membrane actuator as defined by one of the foregoing claims, characterized in that on the inside of the radially outer edge (44) of the membrane (22), a clamping ring (60) or clamping sleeve rests, which ring or sleeve, in particular on the side toward the edge (44), has an encompassing groove or bead (62), which for example serves to partially receive the edge (44), and in particular, the clamping ring (60) or clamping sleeve has a substantially S-shaped cross-sectional form, and the radially outer edge (44) of the membrane (22) is partially gripped from below.
9. The membrane actuator as defined by claim 8, characterized in that the radially outer region (32) of the membrane (22) is restrained or clamped between the inside of the sleeve (38) and the clamping ring (60) or clamping sleeve.
10. A method for producing a membrane actuator (10), in particular as defined by one of the foregoing claims, in particular as defined by one of the foregoing claims, having a housing (20) with a upper housing part (16) and a lower housing part (18), in which method a membrane (22) that has a sleeve (38) on its radially outer region (32) is inserted into the lower housing part (18), and after the insertion of further components, the upper housing part (16) is set on top and joined to the lower housing part (18), and the membrane (22) is vulcanized, glued or welded to the inside of the sleeve (38), characterized in that the membrane (22) is joined to the sleeve (38) in such a manner that its radially outer edge (44) protrudes past the sleeve (38) in the axial and radial directions.
11. The method as defined by claim 10, characterized in that the sleeve (38) is press-fitted into the lower housing part (18), and the prestressing of the membrane (22) is adjusted in particular by means of the press-fitting depth.
12. The method as defined by claim 10 or 11, characterized in that the upper housing part (16) is welded to the lower housing part (18) and/or to the sleeve (38), and in particular upon the welding of teh upper housing part (16) to the lower housing part (18), the sleeve (38) is welded to the housing (20).
13. The method as defined by one of claims 10-12, characterized in that the upper housing part (16) and the lower housing part (18) are produced by deep drawing.

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