EP1206641A1

EP1206641A1 - Membrane pump

Info

Publication number: EP1206641A1
Application number: EP00949341A
Authority: EP
Inventors: Erwin Hauser; Erich Becker
Original assignee: KNF Neuberger GmbH
Current assignee: KNF Neuberger GmbH
Priority date: 1999-08-26
Filing date: 2000-07-14
Publication date: 2002-05-22
Anticipated expiration: 2020-07-14
Also published as: TW482873B; DE50010984D1; DE19940498A1; JP2003507658A; WO2001014744A1; JP4755374B2; US6796215B1; EP1206641B1

Abstract

The invention relates to a membrane pump (104) comprising a working membrane (1) that delimits a delivery chamber (2), and comprising an additional membrane (3) that is arranged on the side of the working membrane (1) facing away from the delivery chamber (2). The inventive membrane pump also comprises a membrane space (4) provided between the working membrane (1) and the additional membrane (3), and comprises a pump drive for effecting an oscillating movement of the working membrane (1) and of the additional membrane (3) in the same direction, whereby the membrane space (3) is connected to at least one suction channel (7) for relieving pressure from the membrane space (4). The inventive membrane pump (104) is characterized in that the membrane space (4) is pneumatically connected to the suction side of said membrane pump (104) via the at least one suction channel (7). The inventive membrane pump (104) is also characterized by having a high suction capacity without causing the elastic working membrane (1)to bulge during the suction phase.

Description

embranpumpe

The invention relates to a diaphragm pump with a working diaphragm delimiting a delivery space, with an additional diaphragm arranged on the side of the working diaphragm facing away from the delivery space, with a diaphragm space provided between the working diaphragm and the additional diaphragm, and with a pump drive for an oscillating movement of the working direction in the same direction. and the additional membrane, the membrane space being connected to at least one suction channel for relieving the pressure in the membrane space.

When designing the diaphragm of a diaphragm pump, the aim is to achieve an optimum between rigidity and elasticity. On the other hand, while a high elasticity of the membrane is required to keep the membrane tensions as low as possible, a high level of stiffness should also be aimed at, so that the membrane does not bulge under the differential pressure load occurring between the top and bottom of the membrane, thus reducing or reducing the pressure volume in the opposite case, the dead space volume is increased.

The aforementioned reduction in the crimp volume in diaphragm vacuum pumps takes place especially in the lower vacuum range. In this area there are large pressure differences between the top and bottom of the membrane. While atmospheric pressure is usually on the underside of the diaphragm, the respective evacuation pressure acts on the top of the diaphragm, the maximum pressure difference resulting from the atmospheric pressure minus the end pressure of the diaphragm pump.

In the case of the usual diaphragms of conventional diaphragm pumps, in particular if these diaphragm pumps work in the area of the ultimate pressure and large pressure loads are exerted on the diaphragms, it should be noted that the lateral elastic zone of the flexible membrane is bulged by the atmospheric pressure towards the delivery chamber. This "blowing out" of the membrane leads to a decisive reduction in the volume of the pumping chamber, which has a negative effect on the pumping speed of the membrane pumps.

This change in shape is particularly pronounced in two- and multi-stage diaphragm pumps with low final pressures. With these pumps, the lower vacuum level is most affected, since the greatest pressure differences occur here.

In order to achieve an optimum between the desired elasticity and the required stiffness of the membrane, more or less good compromise solutions had always been created in the past, whereby good pumping speed could often only be achieved by accepting high membrane tensions.

From DE 40 26 670 AI a membrane pump is already known, the suction side of which is connected via a connecting line to the crank chamber of this membrane pump. In order to be able to at least reduce or even eliminate the pressure difference on both sides of the working diaphragm and in order not to expose the working diaphragm to additional loads due to differential pressure, the crankcase of this known diaphragm pump is connected to its suction side.

The diaphragm pump known from DE 40 26 670 AI has not been able to prevail in practice, however, because the transmission of the driving forces to those located in the crank chamber

Crankshaft and the connection of this crankcase with the suction side of the pump requires an additional shaft seal. However, such a shaft seal comes with further friction losses, higher wear and additional power requirements connected. A vacuum in the crankcase can also lead to outgassing of the bearing grease in the connecting rod bearing, so that the ball bearing may run dry. Since the bearing grease in the crankcase can reach the supply flow on the vacuum side via the connecting line, there is also the risk that the supply medium will be contaminated.

From DE 43 20 963 C2 a multi-stage pump device with a turbo-molecular pump is already known, which is connected downstream of a dual displacement pump designed as a Hybπd pump in the flow path. This Hybπd pump has a reciprocating pump on the medium side, which is followed by a diaphragm pump which ejects the delivery medium. The cylinder chamber of the reciprocating pump is sealed off from the crank chamber by means of a sealing membrane. The space provided between the reciprocating piston on the one hand and the sealing membrane on the other hand is connected to a suction line, which opens in front of a sucking valve of the reciprocating piston pump.

Since this known reciprocating pump has a reciprocating piston, this known pump does not pose the problems that arise with an elastic membrane under pressure differential loads. Rather, in this known piston pump, the space between the piston or its associated sealing sleeve on the one hand and the sealing membrane on the other hand, especially when this known pump device starts up, can be evacuated as soon as possible so that an undesirable overflow from the displacement of the piston pump m eliminates the space or at least largely is avoided and the entire pump device is therefore ready for operation faster when starting.

From DE 43 28 559 C2 a membrane pump is already known type mentioned at the beginning, which has a working membrane, an additional membrane and a membrane space provided between the working membrane and the additional membrane. A suction channel flows into this membrane space, with the aid of which it is possible to bring the membrane space to a lower pressure before the suction channel is closed again.

There is therefore, in particular, the task of creating a diaphragm pump of the type mentioned which can be produced with little effort, which is distinguished by a high suction volume even with a high elasticity of the working diaphragm, and where possible, undesirable impurities in the medium are avoided.

In the diaphragm pump of the type mentioned at the outset, the solution according to the invention for this task consists in particular in that the diaphragm space is pneumatically connected to the suction side of this diaphragm pump via the at least one suction channel.

In the membrane pump according to the invention, the membrane space is pneumatically connected to the suction side of the membrane pump via the at least one suction channel. Thus, the membrane space is continuously evacuated, such that the same pressures always prevail on the top of the working membrane and on the bottom of the working membrane during the suction phase. Since there is no pressure difference between the upper and lower sides of the working diaphragm in this phase, the working diaphragm cannot bulge in the direction of the delivery area and an undesirable reduction in the crimp volume is avoided. The suction capacity can be increased during the suction phase due to the larger head space volume. This has a particularly positive effect in the pressure ranges or pumping speed ranges which are close to the final pressure. The pressure differences only affect the additional membrane, where they have no negative influence can have the suction capacity of the memoran pump.

Since there is no differential pressure on the working diaphragm of the diaphragm pump according to the invention, this working diaphragm can be designed to be highly elastic without fear of the "bulging" of this diaphragm mentioned. Due to the more elastic design of the working membrane, the membrane stresses decrease significantly, which in turn leads to a significant increase in the membrane life. In addition, the shear stresses that occur during flexing work of the working diaphragm can be reduced, the efficiency of the pump can be improved and an evacuation delay caused by bulging of the diaphragm is avoided.

With the help of a more elastic working diaphragm, the diaphragm stroke of the diaphragm pump according to the invention can also be increased, whereby a further increase in the suction capacity can be achieved even with approximately the same dimensions, since there is no atmospheric pressure acting on the underside of the diaphragm of the working diaphragm and the working diaphragm is therefore no longer noisy

If the pump head strikes the delivery space, the development of noise in the diaphragm pump according to the invention is considerably reduced, which has an effect in particular in the case of diaphragm pumps which are to be used as suction pumps in Meαiz technology.

Since only the diaphragm space provided between the working diaphragm and additional meiruoran is connected to the suction side of the pump in the inventive diaphragm pump, and since the crank chamber in the diaphragm pump according to the invention can also continue to be under atmospheric pressure, for example, a special shaft seal is provided in the The area of the crankshaft is not objectionable. In addition, since the grease cannot be expected to penetrate bearing grease, it is certain that undesirable contamination of the medium will occur miss.

A particularly simple embodiment according to the invention provides that the diaphragm intermediate space is pneumatically connected to the pump inlet via the at least one suction channel parallel to the delivery space. In this embodiment, the pump sucks on the one hand through the pump inlet and on the other hand via the suction channel from the membrane space.

In contrast, a further development according to the invention provides that the pump inlet is pneumatically connected to the delivery chamber via the membrane space and the suction channel. In this further embodiment according to the invention, the suction path in the interior of the pump runs from the pump inlet via the membrane space, the at least one suction channel and the inlet valve into the delivery space.

A further proposal according to the invention of its own importance worthy of protection is that at least one suction filter and / or noise damping element is provided in the membrane interspace. Such a diaphragm pump, in which the suction filter and / or noise damping element is arranged in the space between the diaphragms, can be designed to be particularly compact.

In order to additionally counteract any undesired fluttering of the membranes and noise, it is advantageous if the suction filter and / or noise damping element is made of an elastic material and is acted upon by the working membrane and the additional membrane.

A particularly advantageous embodiment according to the invention provides that the intake filter and / or noise Dampungselement essentially fills the membrane space.

The suction filter and / or noise damping element provided in the intermediate membrane space is associated with a particularly low production outlay if it is designed as an open-pore foam element arranged between the working membrane and the additional membrane.

In order to also counter a bulging of the elastic working diaphragm in the ejection phase when the pressure on the top of the diaphragm rises continuously towards atmospheric pressure, a preferred embodiment according to the invention provides that the working diaphragm is assigned a dimensionally stable diaphragm support which is attached to a connecting rod of the pump drive is held and the working membrane on the back of the membrane is supported at least in a central area in a form-adapted manner.

In the case of two-stage diaphragm pumps, the transfer pressure of the first stage is significantly below atmospheric pressure, i.e. During the ejection phase, the pressure on the top side of the working membrane rises only slightly. It is therefore particularly advantageous if the diaphragm pump according to the invention forms the first stage of a multi-stage, in particular a two-stage pump or pump system.

According to a further proposal according to the invention of its own importance, which is worth protecting, it is provided that the working membrane and the additional membrane are integrally connected to one another to form a double membrane. It is useful if the

Working membrane and the additional membrane are integrally connected to one another via a central piece and if this intermediate piece has an undercut fastening opening on its side facing away from the loading area for the insertion of a Form-fitting and connected to a connecting rod of the pump drive fastening part.

It is particularly advantageous if the working diaphragm is designed as a shaped diaphragm, the upper side of the diaphragm on the delivery chamber side of which is form-matched to the contour of the delivery chamber at the top dead center of the pump, as specified by the pump head.

Further features of the invention will become apparent from the following description of exemplary embodiments according to the invention in conjunction with the claims and the drawing. The individual features can be implemented individually or in groups in one embodiment according to the invention.

It shows:

Fig. 1 shows a diaphragm pump with a working membrane, an additional membrane and a membrane space provided between these membranes, the membrane space via a suction channel parallel to

Delivery chamber is connected to the pump inlet,

FIG. 2 shows a diaphragm pump, similar to that from FIG. 1, the delivery chamber being pneumatically connected to the pump inlet via the suction channel and the intermediate membrane space,

3 shows a membrane pump, similar to that of FIG. 1, the working membrane and the additional membrane being connected in one piece to form a double membrane,

Fig. 4 shows the diaphragm pump of Fig. 2, wherein an intake filter and noise damping element made of open-cell foam is provided, which the membrane space essentially filled in and hit on both sides by the membranes,

5 shows a diaphragm pump, similar to that from FIG. 1, the working diaphragm being assigned a dimensionally stable diaphragm support which supports the working diaphragm in the ejection phase,

Fig. 6 is a prior art diaphragm pump with a flat diaphragm, which during the

Indentation differential pressure load, and

FIG. 7 shows a diaphragm pump, which is also part of the prior art, and whose shaped diaphragm bulges in the same way as FIG. 6.

In the previously known diaphragm pumps, efforts are made to achieve an optimum between rigidity and elasticity. A high elasticity of the membrane is necessary to keep the membrane tensions as low as possible. Especially in the high vacuum range, there are large pressure differences between the top and bottom of the membrane. While the respective evacuation process pressure is on the top of the membrane, atmospheric pressure usually acts on the underside of the membrane. As shown in FIGS. 6 and 7, which show conventional diaphragm pumps 106, 107 with Flac memDrane (cf. FIG. 6) and with shaped diaphragm (cf. FIG. 7), the lateral, particularly elastic ring zone of these working diaphragms 1 is shown through the atmospheric pressure bulged in the direction of the delivery space 2 during the suction phase.

This "bulging" reduces the volume of the crimp space and thus reduces the suction capacity of these pumps 106, 107.

The diaphragm pumps 101, 102 shown in FIGS. 103, 104 and 105, on the other hand, in addition to a highly elastic working membrane 1 delimiting a front space 2, also have an additional membrane 3, a membrane intermediate space 4 being provided between the working membrane 1 and the additional membrane 3. The membranes 1, 3 firmly clamped in their outer finger zones in the pump housing 5 act in their central area on the connecting rod of a pump drive which oscillates the working diaphragm 1 and the additional diaphragm 3 in the same direction between an upper dead center and a lower dead center. Of the connecting rod of the pump drive, only the connecting rod head 6 is shown here.

As is clear from FIGS. 1 to 5, the diaphragm space 4 provided in pumps 101, 102, 103, 104 and 105 is connected to the suction side of these diaphragm pumps via a suction channel 7. For this purpose, in the diaphragm pumps 101, 103 and 105 shown in FIGS. 1, 3 and 5, the diaphragm space 4 is pneumatically connected to the pump inlet 8 parallel to the delivery space 2 via the suction channel 7.

In the case of the diaphragm pumps 102 and 104 according to FIGS. 2 and 4, the pump inlet 8, on the other hand, is pneumatically connected to the delivery space 2 via the diaphragm space 4 and the suction channel 7.

Since in the diaphragm pumps 101, 102, 103, 104 and 105 shown here, the diaphragm space 4 is pneumatically connected to the suction side of the diaphragm pumps via at least one suction channel 7, the diaphragm space 4 is continuously evacuated, such that on the top of the The working membrane 1 and the underside of the working membrane 1 always have the same pressure during the suction phase. Since the suction phase thus has no pressure difference between the top and bottom of the membrane of the working membrane 1, the working membrane 1 cannot bulge in the direction of the delivery chamber 2 and an undesirable one A reduction in the crimp volume is avoided. Due to the larger head space volume, the suction capacity can be increased in the suction phase. This has a particular effect on m pressure ranges or suction capacity ranges which are close to the final pressure. The pressure differences only act on the additional diaphragm 3, where they can have no negative influence on the suction capacity of the diaphragm pump 101, 102, 103, 104 or 105. Since there is no differential pressure on the working diaphragm 1 of the diaphragm pumps 101 to 105, this working diaphragm 1 can be made highly elastic without fear of the "bulging" of this diaphragm 1 mentioned.

4 shows that an intake filter and noise damping element 9 is provided in the membrane interspace 4 of the membrane pump 104. This intake filter and noise damping element 9 is made of an elastic material, for example of an open-cell foam, and is acted upon by the working membrane 1 on the one hand and by the additional membrane 3 on the other hand. The suction filter and noise damping element 9, which essentially fills the membrane space 4, is designed in a ring shape, the ring opening 10 of which is penetrated by the connecting rod head 6 of the connecting rod connecting the membranes 1, 3 to one another. Due to the suction filter and noise damping element 9 provided in the membrane interspace 4, parts can be omitted, space can be saved and the membrane pump 104 can be made particularly compact.

In Fig. 5 it is shown that the working diaphragm 1 of the diaphragm pump 105 is assigned a dimensionally stable diaphragm support 11, which is held on the connecting rod head 6 of the connecting rod. While in the single-stage diaphragm pumps 101 to 105 according to FIGS. 1 to 5, the diaphragm space 4 is specifically used in the suction phase in order to increase the volume of the head space, the discharge phase is initiated when the pressure on the top of the diaphragm If the pressure rises in the direction of atmospheric pressure, the diaphragm support 11 is used, which supports the working diaphragm 1 of the diaphragm pump 105 on the back of the diaphragm, at least in a central region, in a form-adapted manner. This keeps the dead space volume small.

In the diaphragm pumps 101, 102, 104 and 105 according to FIGS. 1, 2, 4 and 5, the diaphragms 1, 3 are firmly clamped in the area of a central holding opening 12, 13 on the connecting rod head 6 of the connecting rod. Not only the additional membrane 3, but also the working membrane 1 of the pumps 101, 102, 104 and 105 is designed as a flat membrane.

In contrast, the working diaphragm 1 of the diaphragm pump 103 shown in FIG. 3 is designed as a shaped diaphragm. The working diaphragm 1 is integrally connected to the additional diaphragm 3 of the diaphragm pump 103 via a central intermediate piece 14 to form a double diaphragm 15. As is clear from FIG. 3, the intermediate piece 14 of the double membrane 15 has an undercut fastening opening on its side facing away from the delivery chamber 2, into which a form-fitting fastening part 16 connected to the connecting rod of the pump drive is inserted. In spite of the high elasticity of their working diaphragm 1, the diaphragm pumps 101, 102, 103, 104 and 105 are distinguished by a high pumping speed without any bulging of this comparatively highly elastic working diaphragm 1 being feared in the suction phase.

Claims

claims

1. diaphragm pump (101, 102, 103, 104, 105) with a working diaphragm (1) delimiting a delivery chamber (2), with an additional membrane (3) arranged on the side of the working membrane (1) facing away from the delivery chamber (2), with a membrane space (4) provided between the working membrane (1) and the additional membrane (3) and with a pump drive for an oscillating movement of the working and additional membranes (1, 3) in the same direction, the membrane space

(4) is connected to at least one suction channel (7) for relieving the pressure in the membrane space (4), characterized in that the membrane space (4) via the at least one suction channel (7) with the suction side of this membrane pump (101, 102 , 103, 104, 105) is pneumatically connected.

2. Diaphragm pump (101, 103, 105) according to claim 1, characterized in that the membrane space (2) via the at least one suction channel (7) parallel to the delivery chamber (2) with the pump inlet (8) is pneumatically connected.

3. Diaphragm pump (102, 104) according to claim 1, characterized in that the pump inlet (8) via the diaphragm space (4) and the suction channel (7) is pneumatically connected to the pumping chamber (2).

4. Diaphragm pump (104) according to claim 3, characterized in that in the membrane space (4) at least one suction filter and / or noise damping element (9) is provided.

5. Diaphragm pump according to claim 4, characterized in that the intake filter and / or noise damping element (9) made of an elastic material and on the one hand by the working membrane 1 and, on the other hand, is coated with the additional membrane (3).

6. Diaphragm pump according to claim 4 or 5, characterized in that the intake filter and / or noise damping element

Membrane space (4) essentially fills.

7. Diaphragm pump according to one of claims 4 to 6, characterized in that the intake filter and / or noise damping element (9) is designed as an open-pore and between the working membrane (1) and the additional membrane (3) arranged foam element.

8. diaphragm pump (105) according to one of Anspr che 1 to 7, characterized in that the working diaphragm (1) is dimensionally stable

Membrane support (11) is assigned, which is held on a connecting rod of the pump drive and supports the working membrane (1) on the rear side of the membrane at least in a central area in an adapted manner.

9. Diaphragm pump according to one of claims 1 to 8, characterized in that the diaphragm pump forms the first stage of a multi-stage pump or pump system.

10. Diaphragm pump (103) according to one of claims 1 to 9, characterized in that the working diaphragm (1) and the additional diaphragm (3) are integrally connected to one another to form a double diaphragm (15).

11. Diaphragm pump (103) according to claim 10, characterized in that the working diaphragm (1) and the additional diaphragm (3) are integrally connected to one another via a central intermediate piece (11) and that this intermediate piece (11) on its the delivery chamber (2) side facing a hemcut Fastening opening for inserting a form-fitting fastening part (16) connected to a connecting rod of the pump drive.

12. Diaphragm pump according to one of claims 1 to 11, characterized in that the working membrane (1) is designed as a shaped membrane.