DE1653369A1 - Diaphragm pump, especially for generating a vacuum with aggressive media - Google Patents

Description

Dlpl.lng.Fr.Th-Blm * nn | Must not be changed |

Dipl. Ing. H. Schmitt

Patent attorneys Ι

78 Freiburg I. Brsg,

KarlstraBa 23, Tel. 3 21 9 »

Erich Becker, Steinen / Baden File S 66

S / B

Diaphragm pump, especially for generating a vacuum with aggressive media -

The invention relates to a diaphragm pump, in particular for vacuum generation with valves controlled by the pressure differences of the pumped medium and a connecting rod for moving the membrane, whereby the opening of the supply line leading from the suction valve to the pump chamber is closed by means of the membrane is arranged in the connecting rod oscillation plane near the clamping point of the diaphragm at which it is first lifted, The membrane pump is used in particular to generate a vacuum in aggressive media and the membrane in its central area of this connecting rod and the like in its edge area on the pump housing. is clamped.

Diaphragm pumps of the type mentioned are already known however, it is difficult to obtain suitable membranes for aggressive media. Attempts have to

[Membrane that only _{; ;}

Example demonstrated that a material made of chemically resistant plastic, as it is known under the trademark "Teflon", is not suitable for such pumps. A "Teflon" membrane

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does not seal well and, above all, is not sufficiently elastic to accommodate the forces imposed on it by the connecting rod Movement at the desired speeds and with the required fatigue strength without adverse consequences perform.

Numerous attempts have also been made to produce multilayer membranes. For example, one has

A load-bearing membrane layer from ι ) well-known works st off / seeks to coat Vdem under the trademark Neoprene "K with a thin layer of" Teflon ". It has been found, however, that the" Teflon "layer often does not keep the desired smooth surface and not infrequently even refest after some operating time.

The object is therefore to create a diaphragm pump which is used, in particular, to generate a vacuum, in which the disadvantages of the previous pumps mentioned at the outset are avoided in a simple and safe manner. For this purpose, the invention proposes that the membrane of this pump consists of a membrane and a chemically resistant, thin plastic ^{layer glued to it, for example a "Teflon 11} layer, the adhesive bond extending only to the clamping areas of the membrane. In the clamping areas of the membrane the adhesive can cure without damage; on the other hand, there is no adhesive layer in the areas where the membrane is intensively tumbled during pumping

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lind the rubber layer and the "Teflon ^ layer can be . move independently of one another in this flexing area. Through this become small compressions, bulges and a resulting wrinkled surface on the "Teflon" side Surface of the membrane avoided. This is the case with a diaphragm pump of the type mentioned above is particularly important because a

Flat surface facing the conveying space for sealing rf order! tion of the suction vent i 1 outlet. Furthermore, through

the aforementioned measure according to the invention largely a (|

Avoid tearing of the "Teflon" layer. This is important because aggressive media would otherwise be admitted when pumping to get the chemically insufficiently resistant rubber layer of the membrane and destroy it. The proposed structure is for the latter reason the membrane not only in pumps whose suction valve is closed by means of the membrane, but generally in membrane pumps to use with advantage.

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According to a further development of the invention, it is advantageous that there is between the rubber and the resistant plastic layer no or no ^ at the unrestrained points there is a substantial gap »If the two membrane layers lie tightly on top of one another at these (unglued) points, they can only stand out from one another with a comparatively large amount of force »If, for example, they differ If it is a vacuum pump and there is a negative pressure in the pumping chamber, the "Teflon" layer will still be

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not or only slightly in the direction of the conveying space of the rubber layer lift off because the vacuum in the pumping chamber In addition to the flexural rigidity of the "Teflon" layer, it also separates between this and the rubber layer when it is lifted apart The vacuum that builds up would have to be overcome »Due to the fact that the two membrane layers lie on top of one another, also in the area the untensioned and untied areas especially with vacuum pumps, a reduction in the volume of the conveyed medium by lifting off the two membrane layers avoided from each other.

In a further development of the aforementioned inventive concept suggested that between the rubber and the chemically resistant plastic layer on the non-clamped Provide a comparatively elastic, walkable adhesive. This permanently walkable adhesive causes in In many cases, the plastic and rubber layers hold together better in the non-constrained areas.

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Further details of the invention are based on in the Drawing illustrated embodiments explained in more detail. It shows in different scales: -

Fig. 1 is a vertical cross section through a Meabran pump and in an enlarged view

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Pig. 2 shows a vertical partial cross-section through the an

Membrane glued to its clamping points, as well as these clamping points;

Pig. 3 shows a vertical cross section through a somewhat modified one Membrane similar to Pigur 2 and

Pig. 4 is a plan view of the rubber layer of a membrane and

Fig. 5 is a partial vertical cross-section through a somewhat modified one Membrane similar to Pigur 5.

A diaphragm pump 1 has a connecting rod 2, which leads to a diaphragm, designated as a whole by 3, which is fastened with the aid of a fastening plate 4 to the mushroom-like head side 2a of the connecting rod 2. This and possibly its drive are accommodated in a housing 5, on the top of which there is an intermediate cover 6 which clamps the membrane 3 between its lower edge and the upper edge of the housing 5. The intermediate cover 6 has a recess j which forms the upper end of the pump chamber designated as a whole by ^ 8.

Above the intermediate cover 6 there is a valve plate 9 of known design and above it a cover plate 10, in which, when the pump is designed as a vacuum pump 1, a suction connection 11 and a pressure connection 12 are provided are. The valve plate 9 is largely clamped between the two covers 6 and 10 and has two valves 13 and 14, each hinged to a resilient tongue 15 and 16

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are and each have a passage opening 17 and 18 protrude, which each represent a circular ring sector-shaped opening through the valve plate in the vicinity of the valves 15 and 14 in a likewise known manner. The suction connection located in the cover 10 leads from a connection thread 19 to the top of the suction valve 1J>. Below this in the intermediate cover 6 there is a recess 20 which allows the suction valve IJ to open and from which a feed line 21 leads to the pump chamber 8. On the other hand, a discharge line 22 is provided in the intermediate cover 6, which connects the pump chamber 8 with the underside of the outlet valve 14. Above the outlet valve, a recess 23 is provided in the cover plate, which allows this valve to be opened upwards and connects the discharge line 22 to the pressure connection 12. The opening 2'4 of the supply line 21 is located approximately in the connecting rod oscillation plane and in particular near that clamping point 25 of the membrane 3 * at which it is first raised during operation. This ensures that when the connecting rod moves in the direction of arrow 26, the diaphragm closes the supply line 21 at the beginning of the displacement stroke, as can be seen from FIG. In order to achieve a good, secure closure of the mouth 24, the surface of the membrane 3 facing it should be as smooth as possible, in any case without small bulges, bulges, wrinkles or the like. stay.

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According to the invention, the membrane 5 now consists of a comparatively thick rubber layer 501 and one on top glued, chemically resistant thin plastic layer 502, whereby the adhesive connection is only on the clamping areas 503 or 304 of the membrane 3 extends. As a material for the previously resistant plastic layer 302 has become e.g. the material known under the trademark "Teflon" proved to be well suited. The one clamping area 303 is located on the edge of the membrane, where it is

side of the housing 5 and the adjacent side of the ¹ ^ intermediate cover 6 is clamped (compare in particular Figures I ₄ 2 and 4). The further clamping area 304 lies between the head side 2a of the connecting rod 2 and the fastening platef fastened to it with the aid of the screw 46 (also compare FIGS. 1, 2 and 4). ■

As can be seen clearly from FIGS. 2 and 4, an adhesive 305 is provided in the clamping areas 303 and 304, but also only there. For this purpose, a two-component adhesive, such as is commercially available under the trademark "Uhu-Plus", has proven itself in tests. This adhesive is shown as a thick black line in the figure. In the areas 303 and 304 of this adhesive 305, the "Teflon ^H layer 302 has been etched so that the adhesive can better attack and bond with it. In the area between the clamping areas 303 and 304,

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Intermediate area 306, which can be seen well from FIG. 4, is located there is no adhesive, but there are adjacent surfaces of the membrane 3 where the flexing of the membrane 3 takes place Rubber and plastic layer 301 or 302 only tightly on top of one another. For the sake of clarity in comparison to FIG. 3, FIG FIG. 2 these two layers 301 and 202 also in the intermediate area 306 drawn somewhat separately.

FIG. 2 also shows a further development of the invention recognize after which one of the layers 30I or 302 of the membrane 3i preferably the rubber layer 301 in the clamping areas 303 and 3O4 is designed with a slightly smaller thickness, so that there is a delimited, channel-like zone for the reception of adhesive 305 results.

On the figures 3 and 5 one can - especially in connection with FIG. 4 - recognize further developments according to the invention * At the clamping areas 303 and 304 are the two layers 301 and 302 turn over the securely sealing and reliable bonding adhesive 305 "Uhu-Plus" that hardens over time. There is also the rubber layer 30I made with a slightly smaller thickness. Against it the two layers 301 and $ 302 are in the intermediate area 306 also via a second adhesive 307 in Connection that is permanently elastic and workable, so that the shifting movements occurring in operation

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both layers 301 and 302 are not detrimental to one another Bring Polgen, on the other hand, an unwanted take-off of the two layers 301, 302 from one another even more securely is avoided.

FIG. 5 shows how the rubber layer 301 is made thinner in the clamping areas 303 and 304, but also in the intermediate area 306, but with the areas 303, 306 and 304 each having webs Λ ^{protruding towards the "Teflon w} -look 302"

308 are separated from each other. This will allow the insertion of different adhesives and their limitation against each other relieved.

In particular if one uses only one (hardening) adhesive 305 in the clamping areas 303 and 304, on the other hand in the intermediate area 306 only ensures that there is between the rubber and the "Teflon" layer 30I and 302

as good as no space is formed, it depends on _Λ

that these adhesive areas represent closed areas all around. When using a resilient one Adhesive 307 in the intermediate area 306, this condition can be omitted under certain circumstances. ,

If necessary, with chemically aggressive pump media in Connection coming parts 4, 6, 9 * 10, 46 are known in Way out of these media to be more resilient

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Materials, e.g. made of V4A steel. It also comes in question, the covers 6 and 10 only on their surfaces endangered by the conveying medium with correspondingly resistant To provide surfaces.

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The membrane 5 according to the invention is not only suitable for membrane pumps 1 in which the membrane simultaneously closes the opening 24 of the supply line 21; their design can also be used for other membranes that consist of two layers that are difficult to bond and that are partially clamped.

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Claims (5)

Claims I)) Diaphragm pump, especially for vacuum generation with von the pressure differences of the pumping medium controlled valves and a connecting rod for moving the membrane, wherein the opening of the supply line leading from the control valve to the pump chamber for closing by means of the membrane in the connecting rod oscillation plane near the clamping point of the (J Membrane is arranged on which this is first raised the diaphragm pump is used in particular to generate a vacuum in aggressive media and the diaphragm in their central area of this connecting rod as well as in their edge area on the pump housing od, the like. is clamped, characterized * that the membrane (3) consists of a Rubber layer (jOl / Vs as well as one glued on it, chemically resistant, thin plastic layer, e.g. a "0? eflon" layer (302), wherein the Glued connection only on the clamping areas (303j 304) extends. 2) membrane pump according to claim 1, characterized in that that between the rubber (301) and the resistant Plastic layer (302) at the non-constrained points -12- 0 09835/0660 there is no or no significant gap. 3) membrane pump according to claim 1 or 2, characterized in that between the rubber (301) and the chemically resistant plastic layer (302) a comparatively elastic, permanently walkable adhesive (307) is located. fe 4) diaphragm pump according to one or more of claims to 3, characterized in that the rubber layer (301) of the diaphragm (3) in the clamping areas (303; 304) or in the intermediate area (3O6) ₌ with a slightly smaller thickness is executed> so that there are delimited zones ± Ä for receiving the adhesive or adhesives (305; 307). 5) Diaphragm pump according to one or more of the claims 1 to 4, characterized in that to connect the '' Rubber layer (301) with the chemically resistant plastic layer (302) a two-component adhesive in the clamping areas (305), e.g. "Uhu-Plus" is used, whereby in this adhesive area the chemically resistant Plastic layer, e.g. the "Teflon" layer (302) etched is. Patent attorney 009835/066 0 Empty ropes