EP2188530A1

EP2188530A1 - Multi-level rotary piston vacuum pump or compressor

Info

Publication number: EP2188530A1
Application number: EP08785361A
Authority: EP
Inventors: Uwe Friedrichsen
Original assignee: Busch Produktions GmbH
Current assignee: Busch Produktions GmbH
Priority date: 2007-08-17
Filing date: 2008-08-05
Publication date: 2010-05-26
Also published as: WO2009024262A1; DE102007038966B4; DE102007038966A1

Abstract

In a multi-level rotary piston vacuum pump or compressor, having at least two rotors (6, 7) in the form of rotary pistons, being disposed in a housing (1) on parallel shafts (5, 8) in a rotationally fixed manner, being synchronized counter-rotatable at a ratio of 1:1, each consisting of at least two partial disks (12, 13; 14, 15, etc.) engaging into each other in pairs, the arrangement is such that at least two partial disks (12, 14; 13, 15, etc.) of each rotary piston (6, 7) are configured as one piece, i.e. are manufactured of a single workpiece such upon positioning the individual partial disks of each rotor behind one another a single thread graduation and a sealed working chamber (3.1, 3.2) being closed in itself are formed by means of a cycloidal configuration of the connection surfaces between the shell surface and the core surface of each partial disk, which has a control opening (2) that is configured on the suction side for controlling the gas filling, and has a control opening (4) that is configured on the pressure side for controlling the gas compression.

Description

0 Multi-stage rotary piston vacuum pump or - compressor

The invention relates to a multi-stage rotary piston vacuum pump or compressor according to the preamble of claim 1.

5 Increasing cost pressure at the manufacturers of dry-running vacuum pumps or compressors has meant that in the already established screw or screw vacuum pumps great efforts are being made to reduce the still high production costs for the helical spindle-shaped positive displacement rotors. Nevertheless, the three-dimensional, mostly

! 0 nonlinear surfaces for production a technical challenge. In addition, the cost of machining is still high because the geometries are complex and in the vast majority of cases in the tooth profile an undercut must be provided.

! 5 Compared with the screw or screw vacuum pumps, the equally dry-running claw-vacuum pumps in single-stage design achieve only a final vacuum> 50 mbar abs. for smaller sizes. For larger sizes above a nominal volume flow of about 160 m ³ / h, the achievable final vacuum increases dramatically with increasing nominal volume flow to over 150 mbar abs.

K). For this reason, a variety of claw vacuum pumps was created in multi-stage design, the abs abs <1 mbar abs. for smaller ones Achieve sizes and have been established on the world market for decades. However, such multi-stage claw vacuum pumps are expensive, both in the production as well as in the assembly and maintenance. In addition, they always require many individual parts and often show faults during operation as a result of solid or 5 liquid deposits between the individual pump stages.

In a known rotary piston machine (DE 29 44 714 A1), which operates on the principle of two opposing spirals, the formation is made such that runners and cylinders consist of individual discs. The individual discs

0 are identical in principle in the cross-section, but achieve by varying the outer diameter and the thickness of the discs each desired compression or relaxation of the working gas. The lateral surfaces and core surfaces of the individual rotor disks each have sector angles of 180 °. In addition, the connecting surfaces between these lateral surfaces and

5 core surfaces a dependent on the rotation angle when rolling the rotors variable sealing gap. This is not tightly closing Abrollgeometrien, which has a high leakage result. Due to this insufficient sealing, therefore, such a known rotary piston machine is not suitable for vacuum pumps.

! 0

In another known rotary screw-type rotary engine (DE 29 34 065 A1), only the rotor consists of individual disks in a large variety. The front profiles of the intermeshing discs are identical. Here, the desired relaxation or compression of the working gas by a conical course of

! 5 rotor and cylinder as well as through a decreasing to the pressure side thickness of the discs achieved. This is also a catchy version of the screw rotors, i. the lateral surfaces and the core surfaces of the individual rotor disks each have sector angles of 180 °. The connecting surfaces between shell and core surfaces are omega-like and close the

SO individual chambers when rolling the rotors with a constant sealing gap. However, such a screw-type rotary piston engine is due to the required high number of stepped boundary surfaces with only one manufacture high design effort. For this reason, it is also not suitable for vacuum pumps or compressors.

Finally, in a known rotary piston machine of the generic type

5 Art (AT 261 792) the formation made such that at least two tightly enclosed in a common housing, mutually compulsory rotatable rotary piston are provided, whose axes are parallel to each other, each rotary piston consists of a plurality of pairs interlocking discs.

0

The compression and expansion of the working gas is achieved in that the discs are conical at its periphery and / or narrow in width against the pressure side and are also angularly offset from each other. The lateral surfaces and core surfaces of the individual rotor disks each have

5 sector angle of 90 °, wherein the connecting surfaces are formed therebetween as extended epicycloids and complete the individual chambers when rolling the rotors with a constant sealing gap. A disadvantage here has been found that the number of discs required to form more than two chambers per rotor is too high. This is also the case here

Fert0 manufacturing costs for execution as a vacuum pump too high.

In addition, all three solutions described above are unsuitable for a successful industrial product for two key reasons. On the one hand, the large number of required, partly very thin dividing disks can not be economically produced, i. even unsuitable for mechanical production. On the other hand, the accumulation of unavoidable dead volumes and long gas paths leads to high losses in the working chamber compared to alternative vacuum pumps or compressors.

The invention is therefore the object of the multi-stage rotary piston vacuum pump or compressor of the generic type to eliminate the disadvantages described in such a way that the costly production of Screw geometries or multi-stage claw vacuum pump is bypassed and yet an equal final vacuum, ie far below 1 mbar abs. can be achieved.

5 The features of the invention to solve this problem emerge from claim 1. Advantageous embodiments thereof are described in the further claims.

The invention is based on the essential idea that in each case at least

0 two part discs of each rotary piston integrally formed, i. from a single

Workpiece are made such that when sequentially arranged the individual

Partial discs of each rotor a catchy screw gradation and by cycloidal formation of the connecting surfaces between lateral surface and

Core surface of each disc a self-contained, dense working chamber

15 is formed, the suction side designed to control the gas filling

Control opening and the pressure side has a trained for controlling the gas compression control opening.

This surprisingly simple way the costly production of! 0 screw geometries is avoided and at the same time ensures that nevertheless an equally high final vacuum, i. far below 1 mbar abs. can be achieved. This is achieved by successive rolling Verdrängerrotoren, which in turn consist of simple dividing discs, which are to produce as quasi double or triple unit, by proven two-dimensional processing. ! 5

The invention can be applied to dry-running rotary lobe vacuum pumps or compressors mounted both on the fly and on both sides of the working space, in which the rotors are synchronized in a ratio of 1: 1, for example mechanically by a gear or electronically with a drive motor per IO rotor shaft, inevitably and Non-contact are arranged rotatably against each other. In this case, individual partial disks of the rotors embodied in the form of rotary pistons are combined according to the invention so that in each case at least two Dividing discs of each rotary piston from a single disc, ie, made of a single workpiece, in particular by simple turning and milling, are produced from each of the two end faces. Due to this production of the individual part discs of the rotary piston is not only the processing of the pressure side thin

5 part discs only allows, but it is also the seal between the part discs and the torque transmission itself simplified. Finally, the total number of part discs of the rotary piston can be kept low, among other things, that both the suction side and the pressure side to the working chambers a specially designed control port is present. This is

0 the compression of the working gas by varying the thickness of the disc, possibly also determined by variation of the disc outer diameter and size and shape of the control openings.

In a further development of the invention, it is also possible to make the design in such a way that each rotor consists of at least one three-stage rotary piston whose three partial disks are integrally formed, i. are made of a single workpiece.

As already mentioned, it is within the scope of the invention to adapt the size and shape of the suction-side and / or pressure-side control opening to selected technical parameters, such as gas filling, gas compression, difference between the sector angles of the mantle and core surfaces of the respectively intermeshing part disks, etc.

! 5 It is advantageous if the suction-side control opening has a radial outer sealing edge.

Expediently, furthermore, the design can be made such that the thickness and / or the outer diameter of the partial disks of each rotor decreases from the suction side to the pressure side. The balancing of the rotors in addition to a coordinated mass distribution in the design of the rotary piston can be achieved according to the invention by removing corresponding material, in particular on the suction-side end face of the dividing disks. This can be. can be achieved by forming pockets in the 5 priority suction side thicker individual dividing discs of the rotary piston.

Instead or in addition, it is also possible according to the invention to ensure the balancing of the rotors by producing the part disks from materials of different specific mass.

It is finally within the scope of the invention that the seal between the intermeshing part discs within the working chamber, in particular on the suction side, by an additional static seal, for example by an O-ring 5, is improved.

The invention is explained in more detail below in the form of several embodiments with reference to the drawing. Hereby show:

Fig. 1 shows schematically in section a cantilevered double-stage rotary piston vacuum pump with a total of three double discs;

Fig. 2 shows a section through the housing in front of the rotors according to line M-II with

View of the suction side; ! 5

3 shows a section through the rotors according to line Ill-Ill with a view to the pressure side of the rotors from the transmission side;

FIG. 4 is a plan view corresponding to FIG. 2 of the suction-side partial disks of the rotors meshing with each other, FIG.

Fig. 5 in a perspective view and Fig. 6 in side view, wherein the meshing part discs of both rotors have the same sector angle in shell and core surfaces, namely in each case 180 °;

5 shows a modified embodiment of the part discs of the rotors with a sector angle between the shell or core surfaces of 325 ° or 35 ° in plan view,

Fig. 8 in a perspective view and 0

Fig. 9 in side view;

10 shows a further modified embodiment of the partial disks of the rotors with a sector angle between the lateral surfaces or 5 core surfaces of 270 ° or 90 °, in plan view,

Fig. 11 in perspective and

Fig. 12 in side view.

! 0

As can be seen from the drawing, in particular from FIG. 1, in the illustrated double-stage rotary vacuum pump, the conveying medium is laterally separated from each of one of the alternately formed suction nozzles via a suction nozzle not shown in more detail and via a suction-side control opening 2 arranged in a housing 1

! 5 working chambers 3.1, 3.2 sucked. The pumped medium is then precompressed by different double discs 6.1, 6.2, 6.3 or 7.1, 7.2, 7.3 supplied to the opening of the respective delivery chamber through a pressure-side control port 4 with the desired total compression of the gas outlet.

As can easily be seen, the respective three double disks each form a rotor 6 or 7 in the form of a multi-stage rotary piston. These are mounted on parallel shafts 5 and 8, which are synchronized in opposite directions in the ratio 1: 1 be, by a drive motor not shown on the led out of the housing 1 lower shaft 8 of FIG. 1st

As can be seen from Fig. 2, in this case the suction side of the rotors 6, 7 can be seen, 5 wherein the suction-side control port 2 is adapted in size and shape to the desired gas filling.

In contrast, FIG. 3 shows the pressure side of the rotors 6, 7 from the transmission side, the pressure-side control opening 4 also being formed in a suitable manner with regard to size and shape, that is to say the pressure side. H. adapted to the desired recoverable gas compression.

In the three embodiments according to FIGS. 4 to 6 and FIGS. 7 to 10 and FIGS. 10 to 12, three possible variants are shown, with which catchy ones

5 double disc rotors can be realized. Here are exemplified three different sector angle combinations for core surfaces and lateral surfaces. The first limit value is that the respective intermeshing part discs of both rotors 6, 7 have the same sector angle at the shell and core surfaces, namely 180 °, as shown in Fig. 4 to 6. The second

! 0 limit value consists in a sector angle combination, in which of the respectively intermeshing part discs of both rotors 6, 7, the one part disc the manufacturing and strength technically lowest possible sector angle, namely 35 °, the lateral surface and the corresponding part of disk on the opposite rotor the largest possible Lateral surface, namely over one

! 5 angle of 325 °, as seen from Fig. 7 to 9 can be seen. Finally, FIGS. 10 to 12 show an embodiment in which a sector angle combination has been selected (270 ° or 90 °), which lies between the aforementioned limit values.

In the embodiment according to FIGS. 4 to 6, the sector angles are

Sheath and core surfaces of each disc, as already mentioned, respectively

180 °. In this case, diverging part discs have identical end profiles. To form a flow channel, ie a working chamber over several To realize part discs arranged one behind the other, the corresponding part discs following in the direction of the gas flow are offset at a suitable angle.

5 Here are from FIG. 4, the closely meshing, d. H. revolving cycloid-shaped transitional surfaces 10, 11 between the lateral surfaces and the core surfaces of the first two double discs 6.1 and 7.1 to recognize.

The inventive design of the individual part discs of each rotor. 6

0 and 7 results particularly clearly from Fig. 6. Here are the respective intermeshing part discs 12, 13, then in the direction of the pressure side following then the next intermeshing part discs 14 and 15, 16 and 17, 18 and 19, 20 and 21 and 22 and 23 to recognize. In this case, each two part discs form an item, d. H. are made of a single workpiece. So they form the

5 dividing disks 12 and 14, 16 and 18 as well as 20 and 22 the rotor consisting of three double dividing disks 6. In contrast, the dividing disks 13 and 15, 17 and 19 and 21 and 23 also form the same consisting of three double dividing disks rotor 7. This simplifies As already stated, the production of the individual rotors 6, 7 is very important.

! 0

In the modified embodiment according to FIGS. 7, 8 and 9, the sector angles of the partial disks meshing with each other have the greatest possible difference in the lateral surfaces. Here, the sector angle of the lateral surface of a dividing disk 325 °, while the

! 5 sector angle of the lateral surface of the hereby meshing other part plate is 35 °. Therefore, in this case, each intermeshing partial discs do not have identical end profiles. In order to realize in this case a working chamber via a plurality of successively arranged dividing discs, the following in the direction of the gas flow corresponding dividing discs are offset from each other in a suitable iθ angle. In the embodiment of FIGS. 10, 11 and 12 is finally the

Sector angle of the lateral surface of one of the corresponding one another

Partial disks 270 °, while the sector angle of the other respective part disk meshing therewith is 90 °.

With regard to features of the invention which are not explained in greater detail above, reference is expressly made expressly to the claims and to the drawings.

Claims

claims:

1. Multistage rotary vacuum pump or -Verdichter with at least two in a housing (1) on parallel shafts (5, 8) rotatably arranged in the ratio 1: 1 synchronized counterrotating rotors (6, 7) in the form of rotary pistons, each of at least two pairs of intermeshing part discs (12, 13, 14, 15, etc.) consist, characterized in that in each case at least two part discs (12, 14, 13, 15, etc.) of each rotary piston (6, 7) integrally formed, ie are made of a single piece of work, such that when sequentially arranged the individual

Partial disks of each rotor a catchy gradation and by cycloidal formation of the connecting surfaces between lateral surface and core surface of each disc a self-contained, dense working chamber (3.1, 3.2) is formed, the suction side designed to control the gas filling control port (2) and the pressure side to control Having the gas compression trained control opening (4).

2. Vacuum pump or compressor according to claim 1, characterized in that each rotor (6, 7) consists of at least one three-stage rotary piston, whose three part discs (12, 14, 16, 18, etc.) integrally formed, i. are made of a single workpiece.

3. Vacuum pump or compressor according to claim 1 or 2, characterized in that the size and shape of the suction-side and / or pressure-side control opening (2, 4) to selected technical parameters, such as gas filling,

Gas compression, difference between the sector angles of the shell and core surface of each intermeshing part discs, etc., are adjusted.

4. Vacuum pump or compressor according to one of the preceding claims, characterized in that the suction-side control opening (2) has a radial outer sealing edge.

5. Vacuum pump or compressor according to one of the preceding claims, characterized in that the thickness and / or the outer diameter of the part discs of each rotor decreases from the suction side to the pressure side.

6. Vacuum pump or compressor according to one of the preceding claims, characterized in that the rotors are balanced by appropriate removal of material, in particular on the suction-side end face of the part discs.

7. Vacuum pump or compressor according to one of the preceding claims, characterized in that for balancing the rotors, the dividing discs consist of materials with different specific mass.

8. Vacuum pump or compressor according to one of the preceding claims, characterized in that between each intermeshing part discs within the working chamber, in particular on the suction side, an additional static seal, for example an O-ring is arranged.