METERING DIAPHRAGM PUMP COMPRISING A PROTECTIVE MEMBRANE

Abstract

A metering diaphragm pump includes a metering chamber, a working chamber and a metering membrane. The metering chamber and the working chamber are separated from one another by the metering membrane. A device for moving the metering membrane back and forth between a first and a second position is provided. The volume of the metering chamber is smaller in a first position than in the second position, and a protective membrane is disposed next to the metering membrane on the working chamber side.

Claims

1. A metering diaphragm pump, comprising: a metering chamber, a working chamber and a metering membrane, wherein the metering chamber and the working chamber are separated from one another by the metering membrane, wherein a device for moving said metering membrane back and forth between a first and a second position is provided, wherein a volume of the metering chamber is smaller in a first position than in the second position, wherein a protective membrane is disposed next to the metering membrane on the working chamber side.

2. The metering diaphragm pump according to claim 1, wherein the metering membrane is made of an elastic material, wherein the metering membrane is made of metal.

3. The metering diaphragm pump according to claim 1, wherein the protective membrane is made of an electrically insulating material.

4. The metering diaphragm pump according to claim 1, wherein the protective membrane comprises at least one slot or a milled recess on its side facing the metering membrane.

5. The metering diaphragm pump according to claim 1, wherein a metering membrane tensioning device is provided, which comprises two metering membrane contact surfaces that correspond to one another and between which an edge region of the metering membrane is disposed.

6. The metering diaphragm pump according to claim 5, wherein a protective membrane tensioning device is provided that comprises a protective membrane contact surface between which and the metering membrane an edge region of the protective membrane is disposed, wherein, on a side facing the metering membrane, the protective membrane comprises at least one slot or a milled recess which extends into the edge region of the protective membrane.

7. The metering diaphragm pump according to claim 6, wherein the metering membrane contact surfaces are further away from a centre of the metering membrane than the protective membrane contact surface.

8. The metering diaphragm pump according to claim 6, wherein a bore, in which a membrane rupture signalling device is disposed, is provided in the protective membrane contact surface.

9. The metering diaphragm pump according to claim 6, wherein a textile fabric is disposed between the metering membrane and the protective membrane.

10. The metering diaphragm pump according to claim 9, wherein a tensioning device for the textile fabric is provided, which comprises a contact surface for the textile fabric between which and the metering membrane and an edge region of the textile fabric is disposed.

11. The metering diaphragm pump according to claim 10, wherein the metering membrane contact surfaces are further away from a centre of the metering membrane than the contact surface for the textile fabric and/or the contact surface for the textile fabric is further away from a centre of the metering membrane than the protective membrane contact surface.

12. The metering diaphragm pump according to claim 10, wherein a metering head and a drive head are provided, each of which comprises surfaces that correspond to one another and form the metering membrane contact surfaces, wherein the drive head preferably additionally comprises the protective membrane contact surface and the contact surface for the textile fabric.

13. The metering diaphragm pump according to claim 12, wherein the metering membrane contact surfaces are configured such that the metering membrane is pretensioned in the direction of the first or the second position, wherein the metering membrane contact surfaces are preferably conical.

14. The metering diaphragm pump according to claim 2, wherein the protective membrane is made of an electrically insulating material.

15. The metering diaphragm pump according to claim 2, wherein the protective membrane comprises at least one slot or a milled recess on its side facing the metering membrane.

16. The metering diaphragm pump according to claim 3, wherein the protective membrane comprises at least one slot or a milled recess on its side facing the metering membrane.

17. The metering diaphragm pump according to claim 2, wherein a metering membrane tensioning device is provided, which comprises two metering membrane contact surfaces that correspond to one another and between which an edge region of the metering membrane is disposed.

18. The metering diaphragm pump according to claim 3, wherein a metering membrane tensioning device is provided, which comprises two metering membrane contact surfaces that correspond to one another and between which an edge region of the metering membrane is disposed.

19. The metering diaphragm pump according to claim 4, wherein a metering membrane tensioning device is provided, which comprises two metering membrane contact surfaces that correspond to one another and between which an edge region of the metering membrane is disposed.

20. The metering diaphragm pump according to claim 7, wherein a bore, in which a membrane rupture signalling device is disposed, is provided in the protective membrane contact surface.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] Further advantages, features, and possible applications of the present invention will become apparent from the following description of two preferred embodiments and the associated figures. The figures show:

[0033] FIG. 1 a schematic cross-sectional view through a metering membrane and its tensioning from the prior art,

[0034] FIG. 2 a schematic detail cross-sectional view of a first embodiment of the invention,

[0035] FIG. 2a a schematic plan view onto a protective membrane, and

[0036] FIG. 3 a schematic cross-sectional view of a second embodiment of the invention.

DETAILED DESCRIPTION

[0037] The basic design of the described metering pump is known to the person skilled in the art. Therefore, FIG. 1 only shows a cross-sectional view of a metering membrane 5 which separates a metering chamber 1 from a working chamber 2. The metering membrane 5 is tensioned in its edge regions between the tensioning device 3, 4. The tensioning device 3, 4 consists of two cylindrical elements 3, 4 comprising contact surfaces which face one another and between which the edge region of the metering membrane 5 is clamped. Since the contact surfaces in the shown embodiment are conical with a cone angle α, the metering membrane 5 flexes to the left in the situation shown in FIG. 1 when the two cylindrical elements 3, 4 of the tensioning device are move toward one another and the edge region of the membrane is clamped. Consequently, the elastic metering membrane is pretensioned to the left in FIG. 1 by the shown tensioning device.

[0038] In the preferred embodiment, the working chamber 2 is filled with a hydraulic fluid which can be pressurized with the aid of an appropriate device, such as a driven piston. If the pressure in the working chamber 2 rises above the pressure in the metering chamber 1, the metering membrane 5 is moved even further to the left. This position is shown schematically with the dashed line 5′. If the pressure in the working chamber 2 is decreased, the membrane moves back to the position shown with the solid line 5′.

[0039] Even though the pretensioning described here prevents alternating flexing of the membrane, which significantly increases the service life of the membrane, membrane rupture can still occur in unusual situations and cannot be detected because of the single-layer embodiment.

[0040] FIG. 2 therefore shows a first embodiment of the metering membrane according to the invention in a partial sectional view. The metering membrane 12 is clamped here in a similar manner with its edge region between two elements 11 and 13. The element 11, which can be provided by the metering head, for example, comprises a metering membrane contact surface 18 on which the edge region of the metering membrane 12 rests. The second element 13, which can be provided by the working head or the hydraulic head, likewise comprises a metering membrane contact surface 18 which is in direct contact with the metering membrane 12. The corresponding metering membrane contact surfaces are conical here too, so that the metering membrane 12 is accordingly pretensioned as already known from the prior art. A protective membrane 14 is provided here, however, which is disposed directly behind the metering membrane 12, i.e., in the direction of the working chamber. This protective membrane 14 does not extend as far between the two elements 11 and 13 as the metering membrane 12. The element 13 comprises the protective membrane contact surface 19 on which the protective membrane rests.

[0041] As also in FIG. 2a, for example, which shows a schematic plan view onto the protective membrane 14 in the untensioned state, the protective membrane 14 comprises four recesses 15 which extend from the flexing region 17 of the protective membrane to the tensioned edge region 16 of the protective membrane 14. Should metering fluid therefore actually pass through the metering membrane 12, an intermediate space will form between the metering membrane 12 and the protective membrane 14 and be filled with metering fluid. Because of the recesses 15, the metering fluid reaches the protective membrane tensioning region 16 and can be detected there in a known manner.

[0042] FIG. 3 shows a second embodiment of the invention. Here too, the metering membrane 23 is tensioned between two elements of a tensioning apparatus 21 and 22 in the same manner as in FIG. 2 and the prior art.

[0043] However, two further elements, namely a textile fabric 25 and the protective membrane 24, are now disposed here. The textile fabric 25 does not extend as far between the two elements 21 and 22 as the metering membrane 23, so that the movement characteristics of the metering membrane 23 are not affected by the textile fabric. Lastly, the protective membrane 24 extends even less far between the elements 21 and 22 than the textile fabric 25. The metering membrane 23 is tensioned between the metering membrane contact surfaces 26. The textile fabric 25 configured as a woven fabric is tensioned between the contact surface 27 for the textile fabric and the metering membrane 23. The protective membrane 24 is tensioned between the protective membrane contact surface 28 and the textile fabric 25.

[0044] Due to the presence of the textile fabric 25, there is no need for the corresponding recesses or milled recesses in the protective membrane 24, because any metering fluid that enters the textile fabric 25, which is preferably configured as a woven fabric, can reach the tensioning region of the textile fabric 25 and be detected there in the known manner.

REFERENCE SIGNS

[0045] 1 Metering chamber [0046] 2 Working chamber [0047] 3, 4 Tensioning device, cylindrical elements [0048] 5, 5′, 12, 23 Metering membrane [0049] 14, 24 Protective membrane [0050] 11, 13, 21, 22 Tensioning apparatus [0051] 15 Recesses [0052] 16 Edge region [0053] 17 Flexing region [0054] 18, 26 Metering membrane contact surface [0055] 19, 28 Protective membrane contact surface [0056] 25 Textile fabric [0057] 27 Contact surface for the textile fabric