Membrane vacuum pump

Abstract

A membrane vacuum pump has at least one working space which is bounded by a membrane deformable to change the size of the working space and by a wall in which at least one inlet and at least one outlet are formed for a medium which is sucked into the working space which increases in size in so doing in a suction phase and is expelled via the outlet from the working space which decreases in size in so doing in a compression phase. The membrane vacuum pump furthermore has a controllable actuator unit for deforming the membrane by a contactless action on the membrane by means of electrical and/or magnetic fields.

Claims

1. A membrane vacuum pump, comprising a first working space which is bounded by a membrane deformable to change the size of the first working space and by a wall in which wall at least one inlet and at least one outlet are formed for a medium which is sucked into the first working space in a suction phase via the inlet, with the first working space increasing in size in the suction phase and with the medium being expelled out of the first working space in a compression phase via the outlet, with the first working space decreasing in size in the compression phase; and further comprising a controllable actuator unit for deforming the membrane by a contactless action on the membrane by means of electrical and/or magnetic fields, wherein the pump comprises a second working space, and the membrane separates the first and second working spaces, respectively, which are bounded from one another by a wall, wherein the outlet of the first working space is connected to the inlet of the second working space for forming two pump stages connected in series, wherein each of the first and second working spaces provided with a recess formed in the wall, and the at least one outlet is arranged at a recess center, and wherein the actuator unit is controllable such that the respective outlet of the first working space remains closed by means of the membrane until the inlet of the second working space is closed by means of the membrane.

2. The vacuum pump in accordance with claim 1, wherein the pump has an axis along which the membrane is deformable and which is surrounded by an annular sealing region between the membrane and the wall.

3. The vacuum pump in accordance with claim 2, wherein each of the first and second working spaces is rotationally symmetrical with respect to the axis.

4. The vacuum pump in accordance with claim 1, wherein the membrane is deformable by means of the actuator unit into the recess in the compression phase and out of the recess in the suction phase.

5. The vacuum pump in accordance with claim 4, wherein the recess is rotationally symmetrical with respect to the pump axis.

6. The vacuum pump in accordance with claim 1, wherein the wall defines a curve which is continuously differentiable in every cross-section including the pump axis.

7. The vacuum pump in accordance with claim 1, wherein the membrane is deformable from an outer marginal region inwardly in the direction of the pump axis.

8. The vacuum pump in accordance with claim 1, wherein the actuator unit comprises a plurality of actuators.

9. The vacuum pump in accordance with 26, wherein the plurality of actuators comprise electromagnets or electrodes acted on electrically.

10. The vacuum pump in accordance with claim 1, wherein the membrane comprises a material or consists of a material which is magnetic and/or magnetizable or which is electrorheological or magnetorheological or dielectric.

11. The vacuum pump in accordance with claim 1, wherein the actuator unit comprises a plurality of actuators arranged distributed at the wall outside the working space.

12. The vacuum pump in accordance with claim 11, wherein the actuators are arranged concentrically about the space axis.

13. A membrane pump, comprising at least one working space which is bounded by a membrane deformable to change the size of the working space and by a wall in which wall at least one inlet and at least one outlet are formed for a medium which is sucked into the working space in a suction phase via the inlet, with the working space increasing in size in the suction phase and with the medium being expelled out of the working space in a compression phase via the outlet, with the working space decreasing in size in the compression phase; and further comprising a controllable actuator unit for deforming the membrane by a contactless action on the membrane by means of electrical and/or magnetic fields, wherein the working space is provided with a recess formed in the wall, and the at least one outlet is arranged at a recess center, and wherein the membrane has a variable thickness profile corresponding to shape of the recess formed in the wall.

14. A system, comprising at least two cooperating membrane vacuum pumps which are connected in series and/or in parallel and each having at least one working space which is bounded by a membrane deformable to change the size of the working space and by a wall in which wall at least one inlet and at least one outlet are formed for a medium which is sucked into the working space in a suction phase via the inlet, with the working space increasing in size in the suction phase and with the medium being expelled out of the working space in a compression phase via the outlet, with the working space decreasing in size in the compression phase; and further comprising a controllable actuator unit for deforming the membrane by a contactless action on the membrane by means of electrical and/or magnetic fields, and wherein the working space of each pump has a recess formed in the pump wall with the pump outlet being arranged in the recess center, and wherein the membrane has a variable thickness profile corresponding to the shape of the recess formed in the wall.

15. The vacuum pump in accordance with claim 13, wherein the working space has an axis along which the membrane is deformable and which is surrounded by an annular sealing region between the membrane and the wall.

16. The vacuum pump in accordance with claim 15, wherein the working space is rotationally symmetrical with respect to the axis.

17. The vacuum pump in accordance with claim 13, wherein the inlet can be closed by means of the membrane.

18. The vacuum pump in accordance with claim 13, wherein the membrane is deformable by means of the actuator unit into the recess in the compression phase and out of the recess in the suction phase.

19. The vacuum pump in accordance with claim 18, wherein the recess is rotationally symmetrical with respect to the axis of the working space.

20. The vacuum pump in accordance with claim 13, wherein the wall defines a curve which is continuously differentiable in every cross-section including the axis of the working space.

21. The vacuum pump in accordance with claim 13, wherein the actuator unit is controllable such that the membrane is deformable in a different manner over time and/or in location.

22. The vacuum pump in accordance with claim 13, wherein the membrane is deformable from an outer marginal region inwardly in the direction of the axis of the working space.

23. The vacuum pump in accordance with claim 13, wherein the actuator unit comprises a plurality of actuators.

24. The vacuum pump in accordance with claim 23, wherein the plurality of actuators comprise electromagnets or electrodes acted on electrically.

25. The vacuum pump in accordance with claim 13, wherein the membrane comprises a material or consists of a material which is magnetic and/or magnetizable or which is electrorheological or magnetorheological or dielectric.

26. The vacuum pump in accordance with claim 13, wherein the actuator unit comprises a plurality of actuators arranged distributed at the wall outside the working space.

27. The vacuum pump in accordance with claim 26, wherein the actuators are arranged concentrically about the axis.

Description

(1) The invention will be explained purely by way of example with reference to the enclosed Figures which represent an embodiment of a vacuum pump in accordance with the invention. There are shown:

(2) FIG. 1 a schematic sectional view of a membrane vacuum pump in accordance with the invention; and

(3) FIGS. 2a to 2c schematic sectional views of the membrane vacuum pump in accordance with the invention which illustrate its operation.

(4) FIG. 1 shows an embodiment of a membrane vacuum pump 11 in accordance with the invention in a schematic sectional view. The vacuum pump 11 has a working space which is divided by a membrane 15 into an upper working space 13a and a lower working space 13b. The working space is furthermore bounded by a wall which is composed of an upper wall half 17a and a lower wall half 17b.

(5) The upper and lower wall halves 17a, 17b each have a recess 19 with respect to the membrane 15 which is located in a position of rest in the illustration. In a marginal region 21, the wall, i.e. the respective upper wall half 17a and the lower wall half 17b, comprises inlets 23a, 23b, whereas a respective outlet 25a, 25b is arranged at the center of the recess 19. A gaseous medium which is to be conveyed by means of the pump 11 moves via the inlets 23a, 23b into the working space 13, as is indicated by the arrows 24. The medium is expelled from the outlets 25a, 25b by the pumping process and ultimately moves via lines into a region which is at atmospheric pressure, for example.

(6) The inlets 23a, 25b furthermore comprise a plurality of openings 27 which are located in a sealing region 29 in which the openings 27 are closed by means of the membrane 15 on the expulsion of the medium through the outlets 25a, 25b. The openings 27 can e.g. be provided in the form of circular or slit-shaped apertures.

(7) The vacuum pump 11 furthermore has an actuator unit which consists of an upper actuator unit 31a and a lower actuator unit 31b which are controllable separately from one another. The actuator units each have a plurality of electromagnets 33 as actuators which are arranged outside the working space 13 and outside the respective wall 17a, 17b and are distributed over them.

(8) The membrane 15 comprises a magnetorheological elastomer material. If one or more of the electromagnets 33 are activated, the membrane 15 is pulled in the direction of the activated electromagnet or electromagnets 33 due to the magnetorheological elastomer material, i.e. it is deformed into or out of one of the respective recesses 19 of the respective wall 17a, 17b.

(9) The total arrangement of the vacuum pump 11 is rotationally symmetrical with respect to an axis 35. The electromagnets 33 are thus either respective annular magnets at the individual radial positions or a plurality of respective discrete, individual magnets are provided at the individual radial positions and are uniformly arranged in an annular manner in the peripheral direction. The individual openings 27 of the inlets 23a, 23b are each uniformly distributed over the annular sealing region 29. The radial positions of the electromagnets 33 are uniformly distributed over the respective wall 17a, 17b.

(10) The electromagnets 33 of the actuator units 31a, 31b are controlled by a control device 41. Only connections to the electromagnets 33 of the upper actuator unit 31a are shown in FIG. 1 for reasons of simplicity. The electromagnets 33 of the lower actuator unit 31b are likewise connected to the control device 41. All the electromagnets 33 can be controlled independently of one another so that the membrane 15 can be specifically differently deformable in different part regions.

(11) The function of the membrane vacuum pump 11 in accordance with the invention is illustrated in FIGS. 2a to 2c.

(12) The electromagnets 33 of the upper actuator unit 31a are activated in FIG. 2a, while the electromagnets 33 of the lower actuator unit 31b are deactivated. The membrane 15 therefore contacts the upper wall half 17a, i.e. in its recess 19, due to the magnetic interaction between its magnetorheological material and the electromagnets 33 of the upper actuator unit 31a.

(13) The upper working space 13a is therefore at the end of the compression phase in FIG. 2a and has a size of practically zero. The lower working space 13b, in contrast, is at the end of the suction phase in which the openings 27 of the inlet 23b are open. A check valve, not shown, at the outlet 25b of the lower working space 13b prevents a backflow over the outlet 25b into the lower working space 13b in its suction phase.

(14) The electromagnets 33 of the upper working space 31a are subsequently deactivated, while the electromagnets 33 of the lower actuator unit 31b are activated. The membrane 15 is thereby released from the upper wall half 17a and moves in the direction of the lower wall half 17b. In this respect the actuator units 31a, 31b are controlled such that the membrane 15 reaches the lower wall half 17b in its sealing region 29 at an early time and thus closes the openings 27 of the inlet 23b in the lower wall half 17b to initiate the compression phase of the lower working space 13b.

(15) As soon as the openings 27 of the inlet 23b in the lower wall half 17b are completely closed, the compression phase starts in the lower working space 13b. In FIG. 2b, the lower working space 13b is in the compression phase, while the upper working space 13a is in the suction phase since the openings 27 of the inlet 23a in the upper wall half 17a are open.

(16) The medium to be conveyed is expelled via the outlet 25b of the lower working space 13b in its compression phase. At the same time, a check valve, not shown, at the outlet 25a of the upper working space 13a in turn prevents a backflow into said working space during its suction phase.

(17) The membrane 15 lies at the lower wall half 17b from radially outwardly to radially inwardly during the compression phase to press the gas completely out of the lower working space 13b. As soon as the membrane 15 completely contacts the lower wall half 17b, the electromagnets 33 of the lower actuator unit 31b are deactivated again and a new activation of the electromagnets 33 of the upper actuator unit 31a begins.

(18) The membrane 15 thus carries out a periodic deformation between the upper wall half 17a and the lower wall half 17b overall. The shape of the wall halves 17a, 17b allows a respective complete emptying of the respective working spaces 13a, 13b and is gentle on the material of the membrane 15. The frequency of the periodic deformation of the membrane 15 is controlled via the alternate activation of the electromagnets 33 of the upper or lower actuator units 31a, 31b.

(19) The membrane vacuum pump 11 comprises two pump stages due to the upper and lower working spaces 13a, 13b. These two pump stages can either be connected in parallel in that the inlets 23a, 23b of both the upper wall half 17a and the lower wall half 17b are connected to the same recipient or are connected to a common main pump, for example to a turbomolecular pump. The outlets 25a, 25b are correspondingly connected to one another in such a parallel connection, i.e. they produce a common outlet line (not shown).

(20) Alternatively, the two pump stages of the membrane vacuum pump 11 can also be connected in series, as is shown schematically in FIG. 2c. The outlet 25a in the upper wall half 17a is connected to the inlet 23b of the lower wall half 17b for this purpose. The path of the medium to be conveyed thus extends overall first via the inlet 23a of the upper wall half 17a into the upper working space 13a, subsequently via its outlet 25a and a line 43 (FIG. 2c) to the inlet 23b of the lower wall half 17b, via the inlet 23b into the lower working space 13b and via the latter to the outlet 25b in the lower wall half 17b. The part of the medium through the membrane vacuum pump is illustrated by the corresponding arrows 45 in FIG. 2c.

(21) Since the electromagnets 33 of the actuator units 31a, 31b can each be controlled independently of one another, it is possible to specifically deform the membrane 15 such that the outlet 25a of the upper working space 13a remains closed by the membrane 15 for so long until the inlet 23b of the lower working space 13b is closed by the membrane 15. In other words, the membrane 15 is first only attracted by an activation of the electromagnets 33 of the lower actuator unit 31b in the marginal region 21 or in the sealing region 29 of the lower working space 13b, i.e. is deformed in the direction of the lower wall half 17b, while the membrane 15 is held firm in the central region, i.e. in the proximity of the axis 35, in the recess 19 of the upper wall half 17a. This state, in which the membrane 15 is deformed in a central region in the direction of the upper wall half 17a and simultaneously in a marginal region of the lower wall half 17b, is shown schematically in FIG. 2c.

(22) In the directly subsequent suction phase of the upper working space 13a, no backflow from the lower working space 13b into the upper working space 13a takes place since the inlet 23b of the lower working space 13 is closed before the membrane 15 is released from the outlet 25a of the upper working space 13a. A check valve between the two pump stages, i.e. between the lower working space 13b and the upper working space 13a, can therefore be dispensed with on such a serial connection of the two pump stages of the membrane vacuum pump 11. The outlet 25b of the lower working space 13b, however, still has such a check valve to prevent the backflow.

(23) Alternatively, the membrane 15 can be manufactured from or can comprise an electrorheological material. In this case, corresponding electrodes are used in the two actuator units 31a, 31b instead of the electromagnets 33.

(24) The membrane vacuum pump 11, on the one hand, has the advantages of a conventional membrane vacuum pump, in particular with respect to a dry operation without lubricant such as oil which is required with piston pumps.

(25) The operation of the pump 11 in accordance with the invention is additionally very quiet and low in vibrations.

(26) The membrane vacuum pump is furthermore characterized by a particularly simple and compact construction with a relatively small number of parts and thus by comparatively small manufacturing costs.

(27) In addition, with the membrane vacuum pump 11 in accordance with the invention, the disadvantageous dead volume of conventional membrane vacuum pumps, i.e. a volume in the working space which is not pumped out via an outlet, is avoided in that the membrane 15 completely contacts the upper or lower wall half 17a, 17b in the respective recess 19 at the end of the respective compression phase of the upper or lower working space 13a, 13b.

REFERENCE NUMERAL LIST

(28) 11 membrane vacuum pump 13a upper working space 13b lower working space 15 membrane 17a upper wall half 17b lower wall half 19 recess 21 marginal region 23a, 23b inlet 24 arrow 25a, 25b outlet 27 opening 29 sealing region 31a upper actuator unit 31b lower actuator unit 33 electromagnet, actuator 35 axis 41 control device 43 line 45 arrow