Patent Application
20140166918
The invention relates to a diaphragm valve, in particular for fluid media, having a valve body, a diaphragm and a connecting piece actuatable by a drive unit for operating the diaphragm, wherein the valve body and the diaphragm are made of plastic.
Diaphragm valves having a valve body with an inflow and an outflow (DE 20 2005 002 152 U1) are known in the art. Furthermore, the valve bodies have a valve seat that can be sealed by a diaphragm, wherein the diaphragm is connected via a connecting piece with a pressure piece of a drive unit. The known diaphragms may be formed in one or two layers. WO 2010/025905 A1 describes a single-layer diaphragm, which can also be integrally formed with the connecting piece or which can be formed on the connecting piece. The diaphragm is made of the same plastic material as the valve body, for example of polyethylene (PE) or polypropylene (PP). In addition, the valve body and the diaphragm are fixedly connected to each other by ultrasonic welding to form a fluid-tight valve body unit which can be coupled with the drive unit.
The fixed connection between the valve body and the diaphragm to form a sealed valve body unit allows to form the valve body unit as a disposable unit, and to integrate the diaphragm valve into a disposable tube system or a pre-sterilizable pharmaceutical facility. The valve body unit can therefore be formed inexpensively as a disposable or single-use valve body unit and coupled or connected to a reusable drive unit. The valve body unit is sealed during the transport phase by the fixed connection of the diaphragm and the valve body. Contamination of the valve chamber and the environment is thus avoided. Due to the firm connection of the connecting piece with the diaphragm, the diaphragm can not only be pushed into its closed position but also be pulled into its open position, so that the valve chamber in the valve body can be designed to have a relatively large volume, thereby allowing a sufficiently large volumetric flow for the tube systems of filtration systems. However, it has been observed that the attainable stroke between the closed and open position is not yet sufficient for some applications. In addition, the drive must produce relatively large forces to move the diaphragm of one valve position into the other valve position.
DE 100 62 790 A1 discloses a diaphragm valve having a housing, a diaphragm and an intermediate piece made of plastic. In addition, DE 10 2005 021 583 A1 shows a valve device having an overmolded connecting piece.
It is therefore the object of the invention to provide a diaphragm valve with a diaphragm that can move more easily and has a greater stroke.
This object is attained according to the invention with a diaphragm valve of the aforementioned type by making the valve body and the diaphragm of different plastic materials, wherein and that the plastic material of the diaphragm is more elastic than the plastic material of the valve body.
The diaphragm valve according to the invention has the significant advantage that the driving force for the movement of the diaphragm from the closed to the open position or to substantially less than in the prior art because the plastics material of the diaphragm is more elastic than the plastic material of the valve body. Furthermore, larger strokes can be generated without damaging the diaphragm. This produces larger volume flows and/or the control range is greater for controlled valves.
According to a preferred embodiment of the invention, the diaphragm and the connecting piece are made of different plastics. Here, the plastic of the diaphragm is more elastic than the plastic of the connecting piece. In this way, the flexibility and elasticity of the diaphragm is maintained while it is still ensured that due to the greater strength of the material of the connecting piece the driving forces for moving the diaphragm can be safely introduced into the diaphragm. In addition, the higher strength material of the connecting piece ensures that the connecting piece can be securely mounted on the drive unit.
According to another preferred embodiment of the invention, the valve body and the connecting piece are made of the same plastic material. According to a preferred embodiment of the invention, the connecting piece and/or the valve body are formed of a thermoplastic material, in particular of polyethylene (PE), polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylactate (PLA) polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), polyphenylene sulfone (PPSU) or polyvinylidene fluoride (PVDF).
According to another preferred embodiment of the invention, the connecting piece is overmolded with the material of the diaphragm. According to another embodiment, the connecting piece and the diaphragm are a multi-component injection molded part, in particular a two-component injection molded part. In this exemplary embodiment, the connecting piece and the diaphragm can be manufactured entirely in an injection-mold in a single operation. The connection between the connecting piece and the diaphragm is not only a form-fit, but material mixtures are generated in the transition zone from one plastic material to the other plastic material, which generate a still more intimate connection.
In order to be able to safely transmit, on the one hand, large forces from the connecting piece to the diaphragm and to be able, on the other hand, to treat the diaphragm gently, and to ensure secure anchoring of the connecting piece in the diaphragm, the first region of the connecting piece mounted in the diaphragm has the shape of a mushroom head. The mushroom head has here rounded transition regions, thus eliminating notch effects.
Ion order to draw the diaphragm in during the opening operation, the mushroom head of the connecting piece is curved at its end facing the diaphragm, in particular a concave or convex curvature. This curved region is filled with the material of the diaphragm. The surface area on the mushroom head is increased due to the curvature, improving the connection between the mushroom head and the diaphragm. A concave configuration, which reduces the accumulation of material during production, is preferred.
According to an advantageous embodiment of the invention, the second region of the connecting piece facing away from the diaphragm is designed as a locking pin for mounting the connecting piece on the drive unit. This locking pin is interlocked with the drive unit, which occurs automatically during the initial closing operation. No tool is required for this operation.
According to a preferred embodiment, the locking pin is axially slit and formed as a hollow pin, so that the locking pin has, at least two, in particular four axial fingers having radially protruding latching lugs. This increases the spring action of the locking pin is and facilitates latching or mounting on the drive unit. The latching lugs may hereby protrude radially inward and/or outward.
In order to keep the force as small as possible when attaching the diaphragm on the drive unit, while still securely fasten the diaphragm, the projecting latching lugs have a distal insertion chamfer and a proximal shoulder.
In particular with a single-use valve body unit or one-way valves, there is a need to identify the valve after it has already been used. In a preferred embodiment of the invention, this is readily accomplished in that the locking pin loses its intended use upon removal from the drive unit, i.e. it breaks off, is deformed or cracks. An already used diaphragm valve can therefore be recognized by certain features on the locking pin.
According to another alternative embodiment of the invention, the second region of the connecting piece facing away from the diaphragm has a circumferential groove, for example for an O-ring. Such fasteners are known in the art. The diaphragm valve according to the invention can therefore also be equipped with conventional drive units, without the need to adapt the drive unit.
In this variant, the second region may be axially slit and formed as a hollow pin, so that the hollow pin has at least two axial fingers each having an outer peripheral groove. The forces for locking during attachment, and the release force during release can be adjusted by way of the elasticity of the finger.
In another embodiment of the diaphragm valve according to the invention, the second region of the connecting piece facing away from the diaphragm is constructed as a threaded pin. The threaded pin can be used, on the one hand, to couple the diaphragm directly to the drive unit; on the other hand, an adapter can be screwed onto the threaded pin, so that the diaphragm valve can be equipped with almost all types of drives.
In a preferred, especially separate and independent embodiment of a diaphragm valve, both of the drive unit or of the adapter and the valve body have a so-called QHD sealing contour, which ensures the external leak-tightness of the valve via the pressure applied to the diaphragm by both these components equipped with this contour. Sealing by welding adds an additional seal. The diaphragm valve according to the invention hence has two independent seals toward the outside. The two sealing contours are arranged in a concentric circular pattern. The mechanical QHD clamping seal is radially on the inside and the welded seal is radially on the outside.
Providing two seals has the following background. The welded seal ensures the tightness of the valve to the outside during transport. Once the valve is coupled to the drive unit or to the adapter, the internal pinched seal begins to act.
The reason for this double seal is based on the requirement that the valve must be free of particles. Welding the diaphragm onto the valve body by ultrasound generates a process-inherent particle abrasion. These abraded particles can no longer be flushed out of the valve after welding. However, the abraded particles could be detected as a residue in the liquid and/or gas stream flowing through the valve even when the valve is used as intended.
This problem is solved by arranging the additional QHD pinched sealing edge between the welded sealing edge and the valve seat actually overflowed by the fluid. With this QHD sealing edge, all particles resulting from the ultrasonic welding operation remain trapped between the QHD pinched sealing edge and the weld. When the valve is now mounted on the drive unit or the adapter before it is exposed to process fluid and/or gas, the inner QHD pinched sealing edge seals the overflowed seal seat against the more outwardly located sealing edge or against the possibly generated particles.
Preferably, the material of the diaphragm is in one embodiment an elastomer (such as a natural rubber (NR), an acrylonitrile-butadiene rubber (NBR), a styrene-butadiene rubber (SBR), a chloroprene rubber (CR), a butadiene rubber (BR), or an ethylene-propylene-diene rubber (EPDM)), or a thermoplastic elastomer (TPE), in particular a thermoplastic elastomer on olefin basis (TPE-O), a thermoplastic elastomer on urethane basis (TPE-U), a styrene block copolymer (TPE-S), a thermoplastic polyester elastomer (TPE-E), a thermoplastic copolyester (TPC), a thermoplastic copolyamide (TPE-A).
Additional advantages, features and details of the invention are recited in the dependent claims and disclosed in the following description in which an especially preferred embodiment is described in detail with reference to the drawing. The features illustrated in the drawing and mentioned in the description and/or in the claims may each be essential to the invention either severally or in any combination.
The drawings show in:
The diaphragm 22 is supported on a shoulder 34 of the valve body 20 projecting over the valve seat 32 and seals the valve body 20 with respect to the drive unit 14 and the environment. The valve body 20 is in the exemplary embodiment formed of polypropylene (PP), whereas the diaphragm 22 is formed of a thermoplastic elastomer (TPE). The connecting piece 24, which is coaxially connected with the diaphragm 22 and in particular integrated by a 2-component injection molding process and has a larger width than the valve seat 32, emerges from the rear side 35 of the diaphragm 22 facing away from the valve body 20. The diaphragm 22 has a convex curvature toward the valve seat 32, wherein the corresponding valve seat 32 has a corresponding concave curvature toward the diaphragm 22. This curvature increases the surface area and thus the adhesion. The diaphragm 22 and the valve body 20 are connected to each other liquid-tight and gas-tight in the region of the shoulder 34, in particular by ultrasonic welding.
The drive unit 16 has a substantially cup-shaped housing 36 with an adjusting spindle 38 slideable in the longitudinal direction. The housing 36 can be connected in a known manner from the inside, for example, to a cabinet shelf 40 and secure thereto from the outside via the adapter 18. A pressure piece 44 is screwed onto the free end 42 of the actuating spindle 38, which can be locked to and unlocked from the connecting piece 24.
The second region 50 of the connecting piece 24 of facing away from the diaphragm 22 is designed as a latching pin 52 which is used to fasten the connecting piece 24 on the pressure piece 44. For this purpose, the locking pin 52 has axial slots 54, forming a total of three fingers 56, which have at their free ends radially outwardly projecting locking lugs 58. In addition, the locking pin 52 is hollow and constructed as a hollow pin 59. The locking lugs 58 have a distal inlet chamfer 60 and a proximal shoulder 62 for interlocking in the pressure piece 44. The pressure piece 44 has a receiving bore, into which the locking lugs 58 enter, when the diaphragm valve 10 is closed for the first time, and latch in undercuts provided for this purpose. A relatively low force is required for latching because of the relatively elastic fingers 56 and the inlet chamfers 60. However, the pulling force is high because the shoulders 62 optimally anchor the latching pin 52 in the pressure piece 44. When the latching pin 52 is pulled out of the anchoring structure, the fingers 56 deform to such an extent to cause either a permanent deformation or breakage or cracking. The diaphragm valve 10, in particular the valve body 20, is thereby marked so that it becomes evident that the valve body 20 has previously been installed.
The valve body 20 can be used as a single-use valve body unit, e.g. in sterile pharmaceutical manufacturing, in clean rooms or in the food industry. This reusable valve body 20 can be used in any possible area where plastic valves can be used.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 080 139.1 | Jul 2011 | DE | national |
| 10 2011 084 075.3 | Oct 2011 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/062840 | 7/2/2012 | WO | 00 | 1/10/2014 |
