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(11) | EP 0 159 500 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A rotary eccentric machine for fluids |
| (57) A rotary machine (1) for fluid comprising a working chamber (2) enclosed between
two bodies (3, 4) disposed eccentrically with respect to one another and including
at least one intake aperture (37) and outlet aperture (38) in communication with this
chamber (2). The principle characteristic of this machine lies in the fact that these two bodies (3, 4) are both rotatable with respect to a fixed structure (10) including these apertures (37, 38), and in that these two bodies (3, 4) are joined together by means of at least one associated connection and sealing element (24) defining at least two variable volume chambers (28) such that a rotation imparted to one of the two bodies (4) is transmitted to the other (2). |
[0001] The present invention relates to a rotary eccentric machine for fluids (particularly air) which can be used as a vacuum pump or a compressor, or as a motor driven by fluid under pressure and developing mechanical force usable at an output shaft, and of the type including a working chamber enclosed between two bodies which are disposed eccentrically with respect to one another and having 'an inlet aperture and an outlet aperture in communication with this working chamber.
[0002] Rotary machines for fluid, of this type, have an outer fixed body and an inner body rotating eccentrically. Generally radially disposed blades slidable in suitable grooves formed either in the fixed outer body or in the rotatable inner body define variable volume chambers in the passage from the inlet aperture to the outlet aperture. In either case the blades have to slide in such grooves and to rub on the rotatable or fixed body pressed either by springs or by centrifugal force. This sliding, which causes a considerable purely mechanical loss, also results in wear of the elements of the machine after a time, and principally limits its speed of revolution and therefore its capacity.
[0003] The object of the present invention is to provide a rotatable eccentric machine for fluids which overcomes the above indicated disadvantages, has a relatively simple and therefore economic structure but at the same time is reliable and of high performance and guarantees optimum operation.
[0004] According to the present invention there is provided a rotary machine for fluids, comprising a working chamber enclosed between two bodies disposed eccentrically with respect to one another and including at least an inlet aperture and an outlet aperture in communication with the said chamber, characterised by the fact that the said two bodies are both rotatable with respect to a fixed structure including the said apertures, and by the fact that the said two bodies are connected together by means of at least one associated connection and sealing element defining at least two variable volume chambers, such that a rotation imparted to one of the said two bodies is transmitted to the other.
[0005] For a better understanding of the present invention there will now be described, purely by way of non limitative example, several particular embodiments thereof with reference to the attached drawings, in which:
Figure 1 is a side view, sectioned on the line I-I of Figure 2, of a first embodiment of the rotary machine formed according to the principles of the present invention;
Figure 2 is a sectioned view taken on the line II-II of the machine of Figure 1;
Figure 3 is a sectioned side view of a different embodiment of the machine of the present invention;
Figures from 4 to 8 are sectioned schematic side views of further variations of embodiments of the machine of the present invention; and
Figure 9 is a sectioned view taken on the line IX-IX of the machine of Figure 6.
[0006] With reference to Figures 1 and 2, the rotary machine for fluids, of the present invention, indicated with the reference numeral 1, comprises a working chamber 2 which is enclosed between two rotating bodies 3 and 4 mounted eccentrically with respect to one another. In particular, the outer rotating body 4 has a hollow cylindrical form, and at one end has a lateral closure wall 6 from which extends a shaft 7 which is supported by ball bearings 8 from an end portion of a fixed support structure 10 which widens in correspondence with the cylindrical portion of the body 4 so as to contain it externally with a corresponding annular portion 11. At the outer end of the portion 9 there is positioned a closure plug 12, which carries an annular lip seal 13 which forms a seal on a section 14 of the shaft 7 which projects from the portion 9; another annular lip seal 15, also forming a seal on the shaft 7, is positioned at the inner end of the portion 9. On a threaded section 16 of the shaft 7 there is screwed a ring nut 17 which locks the two ball bearings 8 with the interposition of a spacer sleeve 18. A pulley 22 fixed for rotation with the shaft 7 is locked onto an outer portion 20 of the shaft 7 by means of a nut 21.
[0007] Equally spaced around the circumference of the outer rotating body 4 are fixed the ends of four leaf elements 24 which, at the other end, are fixed, also equally spaced around the circumference, to the inner rotating body 3. In particular, these elements 24 are made of rubber vulcanised onto sheet metal leaves 25 the ends of which are folded in such a way as to create an associated enlarged head portion 26 which is inserted into an associated groove formed on the outer surface of the body 3 and on the inner surface of the body 4 parallel to their axes and of length equal to the axial length of the chamber 2. These leaf elements 24, which have a joining and sealing function, therefore divide the working chamber 2 into four variable volume chambers 28.
[0008] The inner rotating body 3 has a hollow cylindrical form with a lateral closure wall 30 facing the wall 6 and turns, by means of two ball bearings 31, on a shaft 32 which is offset with respect to the axis of the shaft 7. Within the body 3 there is positioned an annular lip seal 33 which forms a seal on the shaft 32, which latter is rigidly connected to a cover portion 34 which has an end wall 50 which closes the other end of the rotating bodies 3 and 4, and is fixed at its perimeter to the end of the annular portion 11 of the fixed support structure 10. In this cover portion 34 there are formed, respectively, an intake duct 35 and a delivery duct 36 which have respective apertures, namely an induction aperture 37 and a delivery aperture 38 in the wall 50, which communicate with the working chamber 2.
[0009] The fluid seal for the variable volume chambers 28 defined by the leaf elements 24 is obtained at the joined ends of the elements 24 by means of the continuous seal defined by the head portions 26 anchored in the associated grooves of the rotating bodies 3 and 4, whilst as far as the facing end walls 6 and 5 are concerned (with respect to which there is a relative rotation) there is a very small axial play (conveniently of the same order of magnitude as that of the axial play of the bearings 31 and 8). Conveniently these leaf elements 24 can be made of ablating material so as to obtain, during operation, a dimensional self adjustment of their end surfaces for sealing on the walls 6 and 50.
[0010] Again for the purpose of improving the fluid tight seal, one or all of the facing surfaces of the bodies 3,4,34 in relative rotation can be ribbed so as to provide a seal of labyrinth type. As is visible in Figure 1, in the detail indicated A, there can be seen ribs 52 formed on the facing surfaces of the wall 50 (fixed) and of the rotating body 3, whilst in the detail indicated B there can be seen ribs 53 formed on the surface of the rotating body 3 which faces the smooth surface of the wall 6 of the rotating body 4. Conveniently, only the surface of the wall 6 or both surfaces could be provided with such ribs. Thus the surface of the rotating body 4 facing the fixed end wall 50 of the cover 34 can also be provided with such ribs.
[0011] The machine 1 illustrated in Figure 3 differs from that of Figure 1 by the omission of the pulley 22 and the end portion 20 of the shaft 7, and by the presence of an electric stator winding 39 housed in the annular portion 11 oi the support structure 10, and a rotor winding 40 housed in the outer body 4. The supply to the stator winding 39 is provided via a contact block 41.
[0012] Moreover the shaft 32, rather than being fixed to the cover portion 34, is fixed to a portion 43 having a knob 44, which can slide rectilinearly within a space 45 defined by the cover 34, between displacement guides belonging to the cover 34 itself. This cover 34 further has portions 46 which carries screws 47 for fixing the portion 43 in the desired position with respect to the cover portion 34.
[0014] With reference to the embodiment of Figures 1 and 2, by exercising an action of mechanical rotation on the pulley 22 the shaft 7 is made to rotate and therefore the outer body 4 is rotated ( in a clockwise sense in the case illustrated in Figure 2) which, via the elements 24, drives the inner body 3 to rotate, which turns on the shaft 32 in an eccentric manner with respect to the outer body 4. The leaf elements 24, in their movement along the working chamber 2, vary in configuration and curvature in such a way as to define variable volume chambers 28 which expand in advance of the induction aperture 37 and compress as they move towards the delivery aperture 38 so as to draw fluid from the induction duct 35 and send it to the delivery duct 36 (in this way the machine 1 can function as a vacuum pump or as a compressor).
[0015] The machine 1 can also function as a motor if compressed air is supplied to the duct 36, which therefore expands in the working chamber 2 and flows out from the duct 35; in fact compressed air acts on the leaf elements 24 which thus drive the bodies 3 and 4 to rotate so that useful mechanical power is obtained at the shaft 7.
[0016] In the embodiment of Figure 2, the rotation at the outer body 4, instead of being provided in a mechanical manner by the pulley 22, is obtained by electric action via the stator winding 39, for which the rotor winding 40 constitutes the rotor of an electric motor.
[0017] Still with reference to Figure 3, the position of the portion 43, and therefore the eccentricity of the inner rotating body with respect to the outer rotating body 4 can be modified and regulated via the screws 47 by varying the distance of the axis of the shaft 32 with respect to that of the shaft 7 such that the capacity of the machine 1 can be regulated.
[0018] The embodiment of the machine 1 schematically illus- strated in Figure 4 differs from that of Figure 1 by the fact that the shaft 7 is a through shaft and is supported, as well as by the bearings 8, also by bearings 48 housed in the cover 34, still being fixed for rotation with the outer rotating body 4 (via a key 49) such that the region of connection for the external mechanical force (motor or load) can be obtained, as is more convenient, from the fixed side of the structure 10 or from the side of the cover 34.
[0019] The embodiment of Figure 5 differs in the fact that the external mechanical force (drive or load) is applied to a shaft 32' which is rigidly connected to the inner rotating body 3, and projects externally from the cover side J4, being supported by bearings 31' housed in this cover 34. The outer rotating body 4 no longer has the shaft 7, but is supported by bearings 8 which are disposed on a fixed spindle 60 belonging to ; the structure 10.
[0020] The embodiment of Figures 6 and 9 differs from that of Figure 1 by the fact that the intake duct 35' and the output duct 36' are formed in the portion 11 of the support structure 10 and in a radial and counterposed direction. The induction aperture 37' and delivery aperture 38' therefore open opposite the lateral surface of the outer rotating body 4 which has wide through slots 60 which form an outlet in a radial sense for the variable volume chambers 28. The fixed part 50 facing the rotating bodies 3 and 4 now no longer has the outlet apertures 37 and 38 and forms a fluid tight seal in the axial direction. The seal against blow-by for the chambers 28 in the radial direction is now obtained by means of a convenient play ( of several hundredths of a millimetre) between the outer surface of the rotating body 4 and the inner surface of the portion 11 of the fixed structure 10 (conveniently of the order of the radial play of the bearing 8); for the purpose of improving this seal such facing surfaces can be ribbed (both or only one) so as to form a seal of the labyrinth type. As is visible in Figure 9, in the detail indicated C, ribs 70 can be seen formed on the outer surface of the rotating body 4 which faces the smooth surface of the inner wall of the fixed portion 11; conveniently, the inner surfaces only of the portion 11 , or both surfaces, may be ribbed.
[0021] The embodiment of Figure 7 differs from that of Figure 6 by the fact that the radial intake duct 35' and outlet duct 36' no longer open radially out from the support structure 10, but are bent in a direction parallel to the axis of the shaft 7 and open into an axial inlet duct 35 and an outlet duct 36 formed in the cover 34.
[0022] Finally, the embodiment of Figure 8 differs from that of Figure 6 by the fact that the shaft 7' is a through shaft, and is supported as well as by the bearings 8 also by bearings 48' housed in the cover 34' which now has a structure similar to that of the support 10. Moreover the shaft 7' is no longer angularly fixed to the outer rotating body 4 but is fixed for rotation with and supports the inner rotating body 3. The outer rotating body 4 (eccentric with respect to the axis of the shaft 7') is supported by two bearings 80 housed in the support 10 and in the cover 34'.
[0023] The machines i of Figures 6,7 and 8, with radial apertures 37' and 38' allow a higher compression ratio between the fluid taken in and the exiting fluid to be obtained.
[0024] The advantages obtained with the machine 1 of the present invention are apparent from what has been described; in particular there is no longer any wear on the elements which define the variable volume chambers, thus permitting greater speeds and higher capacities.
[0025] Finally, it is clear that the embodiments of the present invention described can be modified and varied without
.departing from the scope of the invention itself. For example the leaf elements 24 which have the fundamental characteristics of being flexible can be of the type able to transmit only tractional forces or only flexion- . al forces, or combined forces; for example they may simply comprise metal strips, or else they may comprise a leaft (for example in linen-faced or rubberised fabric) reinforced by metal wires; or can be made of plastics material. Thus also, such leaf elements 24 can be joined at their ends to the bodies 3 and 4 in different ways; for example they can be joined in a fixed manner by adhesive or vulcanisation, or can be locked mechanically by means of fixed blocks with screws or rivets.
[0026] The configuration with the portion 43 for adjusting the eccentricity of the body 3 with respect to the body 4 can also be applied to the other embodiments described, and can also be formed in a different way, and further, the regulation of the eccentricity can be effected with an automatic control system rather than a manual one.
1. A rotary machine (1) for fluids, comprising a working chamber (2) enclosed between
two bodies (3,4) disposed eccentrically with respect to one another and including
an intake aperture (37; 37' ) and an outlet aperture (38, 38' ) in communication with
the said chamber (2), characterised by the fact that the said two bodies (3,4) are
both rotatable with respect to a fixed structure (10) including the said apertures
(37,38; 37' ,38' ) and by the fact that the said two bodies (3,4) are joined together
by means of at least one associated connection and sealing element (24) defining at
least two variable volume chambers (28) such that a rotation imparted to one (4) of
the said two bodies is transmitted to the other (3).
2. A machine according to Claim 1 , characterised by the fact that it includes a plurality
of said connection and sealing elements (24) each of the said elements (24) being
flexible and fixed at its endsrespectively to one (3) and to the other (4) of the
said bodies, and in angularly spaced positions with respect to the other elements
(24).
3. A machine according to Claim 1 or Claim 2, characterised by the fact that the said
elements (24) are operable to transmit traction and/or flexural forces.
4. A machine according to any preceding Claim, characterised Ly the fact that the
said elements (24) comprise a leaf reinforced with metal wires.
5. A machine according to any of Claims from 1 to 3, characterised by the fact that
the said elements (24) comprise metal strips.
6. A machine according to Claim 4, characterised by the fact that the said leaf (24)
comprises linen faced or rubberised fabric.
7. A machine according to Claim 4, characterised by the fact that the said leaf (24)
is made with a plastics material or with rubber vulcanised onto the said metal wires
or on a strip.
8. A machine according to any preceding Claim, characterised by the fact that the
said two bodies (3,4) have an externally circular form and are supported for rotation
by the said fixed structure (10).
9. A machine according to any preceding Claim, characterised by the fact that it includes
mechanical means (22) for externally imparting a rotation to one of the said two bodies
(3;4).
10. A machine according to Claim 9, characterised by the fact that the said mechanical
means comprise a pulley(22)fixed to a spindle (7;7',32' ) which is rigidly connected
to one of the said two bodies (3;4).
11. A machine according to Claim 10, characterised by the fact that it is formed as
a vacuum pump or a compressor.
12. A machine according to any of Claims from 1 to 8, characterised by the fact that
the said rotation of the said two bodies (3,4) is imparted by delivering fluid under
pressure between the said intake apertures (37,37') and outlet apertures (38, 38')
and acting on the said connection and sealing elements (24) such as to obtain useful
mechanical force at a drive shaft (7,7', 32') fixed to one of the said two bodies
(3,4).
13. A machine according to any of Claims from 1 to 8, characterised by the fact that
it includes electric means (39,40) for externally imparting a rotation to one of the
said two bodies (4).
14. A machine according to Claim 13, characterised by the fact that the said electric
means include a stator winding (39) housed in the said fixed structure (11) disposed
about the said outermost body (4) and generating a driving magnetic field for the
said outermost body (4).
15. A machine according to any of the preceding Claims, characterised by the fact
that it includes means (43,45,47) for regulating the eccentricity between the said
two bodies (3,4).
16. A machine according to Claim 15, characterised by the fact that the said regulation
means are actuable with a sensing and control system.
17. A machine according to any preceding Claim, characterised by the fact that the
said intake aperture (37) and outlet aperture (38) are formed on surfaces substantially
perpendicular to the axes of rotation of the said two bodies (3,4).
18. A machine according to any of Claims from 1 to 16, characterised by the fact that
the said variable volume chambers (28) have aperture spaces between the said two bodies
(3,4) facing the said surfaces substantially perpendicular to the axes of rotation
of the said two bodies (3,4).
19. A machine according to any of Claims from 1 to 16, characterised by the fact that
the said intake aperture (37') and outlet aperture (38') are formed on generatrix
surfaces substantially parallel to the axes of rotation of the said two bodies (3,4).
20. A machine according to Claim 19, characterised by the fact that the said intake
aperture (37') and outlet aperture (38') are connected to ducts (35',36') extending
in a direction perpendicular to the axes of rotation of the said two bodies (3,4).
21. A machine according to Claim 19, characterised by the fact that the said intake
aperture (37') and outlet aperture (38') are connected to ducts (35,36) extending
in a direction parallel to the axes of rotation of the said two bodies (3,4).
22. A machine according to any of Claims from 19 to 21, characterised by the fact
that the said variable volume chambers (28) have aperture spaces (60) formed in the
said outermost body (4) between terminal fixing zones for the said joining and sealing
elements (24) on generatrix surfaces substantially parallel to the axes of rotation
of the said two bodies (3,4).
23. A machine according to any preceding Claim, characterised by the fact that it
includes sealing means (52,53,70) for substantially sealing between facing surfaces
in relative rotation of the said two bodies (3,4) and/or of the said fixed structure
(10,34) and/or of the said joining elements (24).
24. A machine according to Claim 23, characterised by the fact that the said means
(52,53,70) include a surface ribbing such as to constitute a substantially labyrinth
seal.