US3459275A - Soundproof compressed-air machine - Google Patents

Description

Aug. 5, 1969 H. PRILLWITZ ET A SOUNDPROOF COMPRESSED-AIR MACHINE Filed Aug. 5, 1968 INVENTORS Hons Prillwitz et a! AGENT United States Patent Ofice 3,459,275 Patented Aug. 5, 1969 3,459,275 SOUNDPROOF COMPRESSED-AIR MACHINE Hans Prillwitz, Klaus Mechiilke, Karl-Heinz, Ktissler, and Bodo Seyfarth, Berlin, Germany, assignors to VEB Niles Pressluftwerkzeuge, Berlin-Pankow, Germany Filed Aug. 5, 1968, Ser. No. 750,355

- rm. (:1. F01n 1/18 US. 01. 181-36 11 Clalms ABSTRACT OF THE DISCLOSURE The invention relates to soundproof compressed-air machines with a piston that rotates in a cylinder of a machine housing; the noise generated by the admitted and discharged compressed air is reduced in these machines.

It is known that compressed-air installations of all kinds-regardless of whether they involve pumps, compressors, blowers or motors-cause extremely intensive noise as they are started up, and also during operation, noise which can damage health.

The exhaust noises are felt to be annoying particularly in compressed-air-driven equipment or machine tools that are intended for manual use because such machines are used primarily in closed rooms which dam up the noise. In addition the noise also affects those workers who are in these rooms but do not themselves work with such machines.

In view of the health-damaging effects of the working noise in industry and economy, increased attention is therefore devoted to measures of noise abatement. Efforts aimed at noise elimination have not yet produced any noteworthy success in the case of compressed-air machines powered by rotary-piston motors, machines which, as is known, represent a particularly strong noise source.

One of the most essential causes of this lies in the fact that in most cases it was necessary to accept impairments in the operational and performance characteristics of the machines.

The attachment of mufflers, which has been practiced, did not prove itself because this results in the structural enlargement of the machines and therefore makes it more diflicult to operate them. It has also been suggested that metallic or non-metallic filters or fillers be built into the exhaust lines of the machines but this suggestion did not prevail in practice because such filters become dirty too quickly and furthermore lead to icing of the air outlets. The resultant performance loss of the machines requires the latters constant regeneration; in addition to the actual servicing functions this causes the temporary shutdown of the machines as far as production is concerned. This is why the use and installation of filter materials have again been discarded in practice.

The invention has as its object to provide a more complete noise reduction in compressed-air machines with rotary pistons. The point of departure here is the task of developing a soundproof compressed-air machine, avoiding structural enlargements 'of the machine and doing without any additional attachments, for instance, in the nature of mufllers applied to the exhaust openings. In this soundproofed machine the oscillating air blasts, which are generated in the interior of the machine by the rotation of the piston which is in the form of a lamellar rotor, are restricted by influencing their direction and speed of flow, as well as by design changes in the air-overflow cross sections as well as the air-outlet openings, and by the installation of damming steps, cutting down on the generation of air and body sound, and thus extensively avoiding sound propagation.

According to major features of the invention, the objects are solved as follows: In the area of a sickle-shaped air-outlet chamber, constituted by a rotor, sealing lamellae, and the inside wall of a cylinder, there is an air-outlet opening which runs axially to the rotor and is constituted by boreholes and slit-like perforations, and an air-outlet opening which in turn runs radially to the rotor and is constituted by boreholes and slit-like perforations, whereby the axial air-outlet opening discharges into a chamber arranged frontally with respect to the cylinder. The radial air opening discharges into a chamber system which surrounds the machine cylinder in the form of a ring. The chamber arranged frontally with respect to the cylinder is in communication with a turbulence chamber via radially positioned air-outlet openings, and said chamber system is in communication with the turbulence chamber via axially arranged overflow boreholes.

A muflling chamber, displaced radially outward with respect to the turbulence chamber and which surrounds the latter in the form of a ring, is in communication with the turbulence chamber by means of a radially arranged overflow borehole, whereby the air-outlet openings leading into the turbulence chamber and from the latter into the muffling chamber, as well as out from the mufliing chamber, are arranged in a radially staggered fashion with respect to each other.

According to other features of the invention, the chamber system which is arranged between the machine housing and the machine cylinder is formed by recesses of differing geometric forms and depths, which are provided in the inside wall of the housing and in the outer cylinder wall, which are radially displaced with respect to each other, and which extend over a portion of the housing as Well as the cylinder so that the crosspieces or webs remaining between the recesses are alternately arranged opposite one of the recesses remaining on the machine housing or on the machine cylinder, respectively, and cover them only over a portion of their width, preferably eccentrically, with a constantly changing overflow cross section between the recesses and the webs.

It is also a feature of the invention that the exhaust air current which leaves the sickle-shaped chamber in a radial direction is subdivided into an air current which runs through the chamber system in one direction and another air current which runs in the opposite direction. Both air currents flow through the machine cylinder and reach the turbulence chamber through overflow boreholes. These boreholes are arranged according to the invention in those recesses of the machine housing which lie closest to the air-penetration or inlet openings in clockwise direction.

Another feature of the invention relates to the provision of a locking ring pushed over a neck portion of the housing, which forms the turbulence chamber, preferably of annular shape. At least one of the recesses forming the chamber system is in communication with the turbulence chamber by way of the appropriate overflow boreholes which are axially disposed with respect to said at least one recess. The latter preferably follows the air-outlet opening running radially toward the rotor in the direction of rotation of the latter.

The turbulence chamber is enclosed by the muifling chamber which, according to a further feature of the invention, is constituted in a simple manner by a closure cap placed frontally on the machine housing.

A further feature of the invention consists in the following: The air-outlet opening which leads into the tur bulence chamber from the chamber provided frontally with respect to the machine cylinder, and the overflow borehole leading from the turbulence chamber into the mufiling chamber, are arranged in a common radial plane but diametrically staggered with respect to each other.

In a similar manner, a radial borehole or air-outlet opening which leads from the mufiling chamber into the .open air is also radially staggered with respect to the overflow borehole leading from the turbulence chamber into the muifiing chamber, and is arranged in a diametrically opposite location.

A further measure for noise abatement in compressedair-driven, hand-operated machine tools according to the invention furthermore consists in that a neck portion of the machine housing (mentioned in connection with the locking ring forming the turbulence chamber), through which its drive shaft protrudes, is designed in the form of a funnel along its inside envelope surface, in the direction of flow of the exhaust air which emerges axially from the sickle-shaped air-outlet chamber, and is designed in an outwardly convex arc-shaped manner. The airoutlet opening arranged frontally with respect to the cylinder and which leads into the turbulence chamber is provided in the area of the first third of the neck portion adjoining the machine housing.

Furthermore it has been proved practical in developing the invention to line the turbulence and the muflling chambers with vibration-damping and sound-absorbing materials. Of course it is also possible to make the aforementioned locking ring and closure cap which constitutes the mufiling chamber from materials with vibrationdamping and sound-absorbing properties, whereby noise reduction is similarly achieved.

To obtain the greatest possible damping effect in the exhaust air which axially emerges from the sickle-shaped air-outlet chamber, the overall cross section of the outlet openings provided for this purpose is greater than that of the air-outlet openings leading from the chamber provided frontally with respect to the cylinder to the turbulence chamber, the ratio being preferably 1 to 2.5: 1. Furthermore, these air-outlet openings have dilferent cross sections which preferably decrease in the direction of rotation of the rotor.

The sources of noise which generate the air sounds in the machine, as is known, exist not only in the area of the air outlet of the machine but also in the area of those places into which the compressed air, necessary for the operation of the machine, is introduced into the interior of the machine. The air inlet into the expansion chamber of the machine has proved to involve a particularly intensive noise level, and this is Why the further development of the invention provides measures to reduce also the air-intake noise.

According to further features of the invention, based on the knowledge of this source of noise generation, the air-inlet opening into the interior of the machine is so designed that a recess or widening is arranged in the interior wall of the cylinder, in the area of the airpenetration or inlet openings which have been made through the cylinder inside wall; this recess expands the air-inlet openings in axial and radial directions, in the manner of a chamber, and is set back toward the outside with respect to the inside wall of the cylinder. The size of this recess or Widening should amount to at least 35% of the cylinder length in the axial direction and have an arc measure of about to /5 of the circumference of the inside cylinder wall in the radial direction.

It is of course also within the scope of this proposal to provide several recesses, instead of just one chamberlike widening of the air-inlet openings, which are disposed axially next to each other and which are set back, as a result of which the noise development occurring at this point is reduced even more eifectively.

In the further development of the invention, the sealing lamellae of the rotor are inserted at dilferent arc intervals with respect to each other; this is done in order to reduce sound generation which is brought about by the lamellae in the area of the air-inlet opening at the moment of passage of the air-infiow cross section due to the cutting of the air column, and to reduce, as much as possible, the oscillations generated at this point through interference phenomena.

As a result of this, the contact surfaces of the individual sealing lamellae which follow in the direction of rotation of the rotor have different intervals on the sliding surface of the cylinder which surrounds the rotor so that there is a change in the generated frequency band of the air column oscillating at these places, resulting in noise reduction, at the intersection of the airintake openings leading into the working space of the cylinder as 11 We as those of the overflow openings located in the area of the air-outlet chamber.

The dilfering arc interval between the individual sealing lamellae of the rotor can however also be produced according to the invention by designing the lamellae in an outwardly conical manner, on one or both sides, tapering in wedge fashion, or by inserting them into the rotor alternatingly following each other in radial direction, or in the plane of a chord.

With a compressed-air machine built according to the invention, considerable noise reduction can be achieved because effective influence is exerted both on noise generation and on sound propagation, through design, structural, and flow-technical measures.

Other objects, features and many of the attendant advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description, when considered with the acompanying drawing, wherein FIG. 1 is a partial longitudinal cross section through a compressed-air machine according to the invention, powered by a rotary-piston motor;

FIG. 2 is a sectional view of the machine along section line 2--2 in FIG. 1; and

FIG. 3 is another sectional view of the machine along section line 3--3 in FIG. 1.

On a machine housing '1 of a compressed-air machine equipped with a rotary-piston rotor there is provided in a known manner a neck portion 2 through which a drive shaft 3 is guided. Into a cylindrical part of housing 1 there is inserted a cylinder 4 which receives in an eccentric borehole a rotor 5 journalled in housing 1. Rotor 5, in a customary manner, has several slit like recesses 6 which are radially displaced along the circumference for the reception of sealing lamellae 7a, 7b, 7c and 7d, and rotates in direction D, shown by an arrow in FIG. 2. Cylinder 4 is partly traversed in an axial direction by an air-supply duct 8 from which an air-penetration or inlet opening 9 is made, in radial fashion, through the inside cylinder Wall 10.

In the area of the opening 9, there is arranged a recess or widening 11 which enlarges this opening in axial and radial directions in the form of a chamber, and which is set back with respect to the cylinder wall 10. The size of this widening 11 partly depends on the structural size of the machine and should be at least 35% of the particular cylinder length and, in radial direction, about to /s of the circumference of the inside cylinder wall 10.

An expansion chamber 12, located in the area of open ing 9 and widening 11, formed by rotor 5, cylinder 4 and lamellae 7a and 7b, can be supplied with compressed air in the rotor position illustrated in FIG. 2. Roughly diametrically opposite to expansion chamber 12 there is an air-outlet chamber '13 constituted by rotor 5, cylinder 4 and lamellae 7c and 7d; the expanded compressedair is evacuated from the interior of the machine by way of this chamber 13.

In accordance with one of the characteristic features of the invention, this is accomplished through the subdivision of the exhaust-air current into two different directions or flow paths. For this purpose, one or more airoutlet openings 14 lead out of chamber 13 through a running and sealing plate 15 arranged axially in front of the rotor into a pressure chamber 16 constituted by neck portion 2 of housing 1.

Openings 14 are formed by boreholes and/or slit-like perforations and they are arranged axially toward the chamber 13 in plate 15. The other smaller part of the exhaust air to be evacuated from the chamber 13 leaves the same via air-outlet openings 18 which lie radially toward chamber 13, which openings are preferably constituted by boreholes and which lead into a chamber system arranged between housing 1 and cylinder 4. Details of the chamber system will be given somewhat later in the description.

Openings 18 which traverse the cylinder 4 radially in the area of air-outlet chamber 13 and which, instead of boreholes, can also be made in the form of slit-like perforations, are arranged in radial and axial planes toward each other and are staggered by fraction of the frequency of the oscillating air column which passes from chamber 13 into the chamber system in order to generate an interference in the radially emerging exhaust current.

The chamber system is constituted by recesses 17a to 17g and 17A to 17F of differing geometric forms and depths, which are provided in inside wall 19 of housing 1 and in outer cylinder wall 20, and which are radially displaced toward each other and which extend over a portion of the cylinder length in such a fashion that the crosspiece or webs which remain on cylinder 4 and on housing 1 between the recesses 17a 17F are alternately arranged one each opposite a recess remaining on housing 1 and/or on cylinder 4, respectively, covering them only for a portion of their width, preferably eccentrically. According to the invention, the overlap is so provided that there develops a changing overflow cross section from one recess to the next in the exhaust air which flows through the chamber system in the directions of flow E and F (see FIG. 2).

Overflow boreholes 21 are provided in one or more recesses arranged in housing 1 and belonging to the chamber system. These boreholes 21 are made in an axial direction through housing 1 and are in communication with a turbulence chamber 23 which is provided in neck portion 2 of the machine and which is constituted by a locking ring 22. The ring is here pushed onto a cylindrical, machined portion of neck 2.

According to the invention it has proved to be particularly eflective to place overflow boreholes 21 which are in communication with turbulence chamber 23 in recesses 17b, 17c and 17d of housing 1, which follow the airoutlet openings 18 in clockwise direction, that is, in the direction D in which rotor 5 rotates. It is also possible and sometimes feasible to provide these boreholes 21 in other recesses of the chamber system.

In the area of turbulence chamber 23, although radially staggered toward the outside with respect to the latter, there is arranged a mufi'ing chamber 25 constituted by a closure cap 24. The cap can here be placed on a collar on neck portion 2 of housing 1 and can be detachably connected with the housing by means of a clamping connection.

For the purpose of sound absorption, ring 22 and cap 24 are preferably made of sound-proofing materials, for instance, hard rubber. It is also possible to line one or both of these structural parts with sound-absorbing materials, so that chambers 23 and 25 will have a soundabsorbing and thus noise-reducing effect.

Turbulence chamber 23 is connected, on the one hand, by means of an air-outlet opening 26 passing through neck portion 2 with pressure chamber 16 and, on the other hand, by an overflow borehole 27 provided in ring 22 with mufiling chamber 25. From the latter, a radial borehole 28 made in the outside surface of closure cap 24 leads into the open. As FIGS. 1 and 3 illustrate, outlet opening 26 faces overflow borehole 27 in the same radial plane.

Similarly, radial borehole 28 faces borehole 27 in the above-mentioned radial plane. Neck portion 2 conically tapers along its inside surface, starting from rotor 5 of the machine and from the plate 15, respectively, but it may also be designed in an outward arc-shaped swing. As is desired according to another characteristic of the invention, this produces a turbulence in the main exhaustair current G which axially emerges from air-outlet chamber '13 and is guided into pressure chamber 16. In neck portion 2 which is reduced toward the front as explained before and whose cross section thus becomes smaller a kind of pressure cushion C is formed due to the outflowing exhaust air, and the entering exhaust air is braked, diverted and swirled around at the pressure cushion.

Roughly in the radial plane of air-outlet opening 26 there forms under these flow conditions a zone of moderate air pressure from which the exhaust air leaves pressure chamber 16 through opening 26 and is conducted into turbulence chamber 23. The swirling of the main exhaust-air current in chamber 16 is here further promoted by the continuously rotating drive shaft 3 which is guided through chamber 16.

Lamellae 7a, 7b, 7c and 7d which are inserted in a known manner in rotor 5 of the compressed-air machine are arranged in a slightly radially staggered fashion with respect to each other in such a way that there is a ditfering interval between contact surfaces 29 of the individual sealing lamellae, following each other in the direction of rotation of rotor 5, in the area of the sliding surface (inner wall) 10 of cylinder 4 which surrounds rotor 5, with reference to the center plane of the individual contact surfaces. For this purpose, lamellae 7a to 7d can be reduced at their ends, on one or on both sides, facing cylinder 4, or they can be designed in an outwardly conical fashion.

The operation of the compressed-air machine according to the invention is as follows: The compressed air which is introduced via air-supply duct 8 passes through air-inlet opening 9, and which enters expansion chamber 12, sets rotor 5 of the machine in a rotating motion as a result of the expansion occurring at this point. The individual sealing lamellae 7a to 7d continually intersect the compressed-air current which enters chamber 12. In this process they generate air oscillations which are noticeable on the outside as noise from the compressed air entering the machine.

This noise has a particularly annoying and healthdamaging effect when the air oscillations are generated at relatively high frequency. This is the case when the airinlet opening 9 leading into chamber 12 is constituted by a large number of air ducts with relatively small cross sections, as can be seen in compressed-air machines of conventional design.

The chamber-like widening 11 of opening 9, designed according to the invention, in a most perfect manner prevents this very intensive noise generation in that the entering air current is intersected only once each time the sealing lamellae pass. Of course, the compressed air is still set in oscillation as a result of this, although in a frequency range which is no longer felt to be disturbing and healthdamaging.

The expanded compressed air leaves the cylinder space through air-outlet chamber 13 and is conducted from there into the open. According to the invention, the exhaust-air current leaving chamber 13 is subdivided into two air currents, by the arrangement of air-outlet openings 14 disposed radially with respect to chamber 13, and by the provision of air-outlet opening 18 positioned radially with respect to chamber 13 in order, on the one hand, to

make available to the further expanding air a volume that will be as large as possible and that will produce noise reduction and, on the other hand, to create effective possibilities for producing phenomena of interference as well as of reflection and absorption of the emerging air volumes.

For this purpose, the exhaust-air current which passes openings 14 and which leaves chamber 13 in an axial fashion enters pressure chambers 16 and generates in the latters forward, narrowed part a kind of air cushion C, as schematically indicated in FIG. 1. During the influx of this part of the exhaust air, the air current is so influenced, in terms of flow, by the design of the inside surface of neck portion 2 that the exhaust-air current G is braked, diverted, and made to swirl at the air cushion C.

Through these phenomena, a zone of moderate pressure is formed in the rear part of pressure chamber 16, roughly in the area of air-outlet opening 26 disposed thereat. From this zone, the exhaust air is conducted through opening 26 to turbulence chamber 23. Very advantageous here is the fact that the cross section of airoutlet opening 26 is smaller than the total cross section of air-outlet opening 14.

In turbulence chamber 23 this portion of the exhaust air meets the exhaust-air current which has left airoutlet chamber 13 in a radical direction. But before the exhaust-air current, radially leaving chamber 13, gets into turbulence chamber 23, it has run through the chamber system. This is done in a manner that the radially emerging exhaust-air current is subdivided in the chamber 17a provided in housing 1 and is diverted into flow directions E and F. The air currents which are conducted into cylinder chambers 17A and 17F through air-outlet openings 18 are here accordingly influenced by the flow directions E and F.

These two exhaust-air currents run through the chamber system in the direction illustrated in FIG. 2. As a result of the constantly changing overflow cross sections, they experience a several times repeated unequal pressure and speed change. The ensuing turbulence and acoustic filtering of these air currents has an advantageous effect with respect to the desired noise abatement in that the noise spectrum generated by these oscillating air currents is altered. These air currents leave the chamber system through overflow boreholes 21 and move from there into turbulence chamber 23.

Through the arrangement of boreholes 21 in accordance with the invention and through their spatial intervals there is achieved an interference in the passing air currents E and P which then leave the chamber system; this promotes the reduction of air noises and/or machine noises. As explained above, the air currents E and F are here combined with the exhaust-air current guided out of pressure chamber 16. As illustrated in FIG. 3, a renewed diversion of the air currents takes place in turbulence chamber 23, as shown by the arrows H and K, respectively.

The air current which emerges from pressure chamber 16 and which has a larger volume and a greater intensity brings with it the air current which has entered chamber 23 through overflow boreholes 21. The now combined exhaust air leaves turbulence chamber 23 through overflow borehole 27 and moves into muflling chamber 25. Here the exhaust-air current is once again divided and diverted, and it runs through chamber 25 in two directions of flow, namely L and M. As they meet, these air currents are once again broken up in the area of radial borehole 28, and their flow intensity is reduced until they finally leave mufliing chamber 25 through borehole 28 and pass into the open.

According to the invention, turbulence chamber 23 and muflling chamber 25 are preferably made of noisereducing materials; in the area of action of the air discharged from the machine, this brings about a further noise reduction, whereby the structural size of the machine is not impaired due to the novel arrangement of shape of these chambers 23 and 25, while creating the greatest possible noise-reduction volume. Compared to conventional muffled compressed-air machines, this circumstance has an advantageous effect.

In practice it was shown that soundproof compressedair machines built according to the invention and corresponding measures taken for purposes of noise reduction on compressed-air machines equipped with rotarypiston motors do not have any disadvantages on the operational and performance characteristics of the machines, such as this was observed throughout on conventional compressed-air machines of the muflled or soundproofed version.

Influencing the generation of air and body sounds within the machine, according to this invention, the measures for the prevention of sound propagation, taken in terms of flow engineering and construction, finally the preventive measures taken for noise reduction, and also the transfer of the noise spectra into areas which have less health-damaging effects, bring with them a significant increase in the utility value of compressed-air machines.

It is not even required to use in their totality the measures for sound reduction according to the invention. It is on the other hand possible and in certain cases feasible to use only one or the other of these measures for noise diminution.

Similarly it is within the scope of the invention to use one or the other of the measures described for noise reduction also on compressed-air machines of different structural types. This includes furthermore the possibility of, for example, providing the described turbulence and mufiling chambers somewhere else on the machine body, where, for instance, they would be better placed for reasons of space or construction.

What we claim is:

l. A soundproof compressed-air machine having a housing (1), a piston rotating in a cylinder (4) having an inside wall (10), a rotor (5) in said cylinder, a drive shaft (3) for said rotor and sealing lamellae (7a to 7d) on said rotor; comprising, in combination, a first or airoutlet chamber (13) constituted by said rotor, said lamellae and said inside wall; at least one first or air-outlet opening (14) provided in the area of said first chamber and serving for the exhaust air which emerges therefrom; at least one second or air-outlet opening (18), running radially to said rotor while said first opening runs axially thereto; a second chamber (16) arranged frontally with respect to said cylinder, said first opening discharging into said second chamber; a chamber system (17a to 17g, 17A to 17F) arranged between said housing and said cylinder, and surrounding the latter, said second opening discharging into said chamber system; a third or turbulence chamber (23), said second chamber being in communication with said third chamber via radially positioned third or air-outlet openings (26); said chamber system being in communication with said third chamber via axially arranged first overflow boreholes (21) provided in said housing; and a fourth or muffling chamber (25) displaced radially outward with respect to said third chamber and which surrounds the latter and has a radial borehole (28) leading from said fourth chamber to the open air; said fourth chamber being in communication with said third chamber by means of a radially arranged second overflow borehole (27 2. The machine as defined in claim 1, wherein said third openings (26) and said first overflow boreholes (21) leading into said third chamber (23), as well as said radial borehole (28) and said second overflow borehole (27) leading respectively into and out from said fourth chamber (25), are arranged in a radially staggered fashion with respect to each other.

3. The machine as defined in claim 1, wherein said third opening (26) and said second overflow borehole (27) are arranged in a common radial plane but diametrically staggered with respect to each other.

4. The machine as defined in claim 1, wherein said first openings (14) have cross sections decreasing in the direction of rotation of said rotor 5. The machine as defined in claim 1, further comprising a closure cap (24) placed frontally on said housing (1), which constitutes said fourth chamber (25), the latter enclosing said third chamber (23).

6. The machine as defined in claim 1, wherein said radial borehole (28) is radially staggered with respect to said second overflow borehole (27).

7. The machine as defined in claim 1, wherein the overall cross section of said first openings (14) is greater than that of said third openings (26), the ratio of the cross sections of said first and said third openings being between 1 and 25:1.

8. The machine as defined in claim 1, wherein said housing (1) has therein fourth or air-inlet openings (9) leading through said inside cylinder wall (10) and being provided with at least one widening (11) in said inside wall, said widening expanding said fourth openings in axial and radial directions and being set back toward the outside with respect to said inside wall.

'9. The machine as defined in claim 8, wherein the size of said widening (11) amounts to at least 35% of the length of said cylinder (4) in the axial direction and has an arc measure of about to /5 of the circumference of said inside cylinder wall (10) in the radial direction.

10. The machine as defined in claim 1, wherein said houseing (1) has a neck portion (2) through which said drive shaft (3) protrudes, constituting an exhaust outlet for the air which emerges axially from said first chamber (13).

11. The machine as defined in claim 10, wherein said neck portion (2) is given substantially the shape of a funnel narrowing toward said exhaust outlet.

12. The machine as defined in claim 10, wherein said third openings (26) are provided in the area of the first third of said neck portion (2) adjoining said housing (1).

13. The machine as defined in claim 1, wherein the outer ends of said lamellae (7a to 7d) constiute contact surfaces (29) sliding along said inside cylinder wall (10) and having different intervals in the region of said inside wall in the direction of rotation of said rotor (5), related to the center plane of said contact surfaces.

14. The machine as defined in claim 13, wherein said lamellae (7a to 7d) have an outwardly conical shape on at least one side, thereby producing a differing arc interval.

15. The machine as defined in claim 1, wherein said chamber system (17a to 17g, 17A to 17F) is formed by recesses of diifering geometric forms and depths, which are provided in the inside wall (19) of said housing (1) and in the outer wall (20) of said cylinder (4), said recesses being radially displaced with respect to each other, and extending over a portion of said housing as well as said cylinder so that webs remain between said recesses, which are alternately arranged opposite one of said recesses, and cover them only over a portion of their width, with a changing overflow cross section between said recesses and said webs when the machine is in operation.

16. The machine as defined in claim 15, further comprising a locking ring (22) pushed over a neck portion (2) of said houseing 1) and forming said third chamber (23) which has an annular shape, at least one of said recesses (17a 17F) being in communication with said third chamber by way of said first overflow boreholes (21), the latter being axially disposed with respect to said at least one recess.

17. The machine as defined in claim 16, wherein said at least one recess (17b, 17c, 17d) follows said second opening (18) in the direction of rotation of said rotor 5).

References Cited UNITED STATES PATENTS 2,057,262 10/1936 Osgood. 2,789,652 4/ 1957 Fannen. 3,330,378 7/1967 Waldron 181-36 ROBERT S. WARD, JR., Primary Examiner U.S. Cl. X.R. 181-57 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,459,275 August 5, 1969 Hans Prillwitz et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, lines 68 and 69, cancel "circumference of the;

line 69, "radial" should read circumferential Column 4, line 64, "radial" should read circumferential line 65, cancel "the circumference of". Column 6, line 71, "radially" should read axially Column 9, lines 25 and 26, cancel 'the circumference of"; line 26, "radial" should read circumferential Signed and sealed this 12th day of January 1971.

(SEAL) Attest:

WILLIAM E. SCHUYLER, IR.

Commissioner of Patents Edward M. Fletcher, J r.

Attesting Officer

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