GB2054094A

GB2054094A - Subcircular Type Flywheel

Info

Publication number: GB2054094A
Application number: GB8017429A
Authority: GB
Original assignee: Airbus Group SAS
Current assignee: Airbus Group SAS
Priority date: 1979-05-29
Filing date: 1980-05-28
Publication date: 1981-02-11
Also published as: FR2458005A1; EP0020261A1; JPS55159350A; CH643041A5; EP0020261B1; FR2458005B1; DE3020497A1; GB2054094B; CA1146379A; IT8048805A0; DE3020497C2; DE3066944D1; IT1143166B

Description

1 GB 2 054 094 A 1

SPECIFICATION Subcircular Type Rotor and Method for Its Construction

The present invention relates to subcircular rotors, that is to say those for which the rotation induces them to stretch towards circularity without however achieving it, and it relates more particularly to a rotor of this type used as an inertia wheel for energy storage/recovery uses.

SubcIrcular rotors were disclosed for the first time by Applicant in his French patent No.

08394 of 9 March 1970 which shows a wall web-hub rotor characterised in that it comprises an outer wall supported on radial webs integral with an axial central hub, the curvature radius of sectors of said wall between two consecutive webs being higher than the outer radius of said webs in such a way that during rotation the application radius has the tendency of approaching said outer radius of the webs under 85 the effect of the centrifugal force, the application of the wall to the webs constituting a hub-webs wall assembly of very high rigidity.

In the invention described in the above mentioned patent, the radial forces exerted by the wall on the webs are relatively low and can be withstood by the webs forming a light one-piece unit with the hub; this is not the case when the radial forces become considerable in an arrangement of the rotor as an inertia wheel in which the rim is thick.

In such a case, in fact, the webs must withstand considerable radial compressive stresses, which involves a large size of the latter, notably to withstand the effects of buckling.

The mass which results from such dimensions 100 constitutes a useless dead-weight which does not contribute to rendering subcircular rotors effective in the above-mentioned inertia wheel conformations. In addition, a second problem subsequent to the first resides in the realisation of 105 balancing means of a subcircular rotor which, according to the concept of the invention of said prior patent does not raise any particular difficulty but which, in the configuration proposed as an inertia wheel in the present invention, constitutes on the contrary a major problem which is difficult 110 to solve.

In fact, the placing of the inertial axis of a rotor in strict and permanent coincidence with the axis of rotation remains one of the most difficult problems to resolve.

In addition, in his British patent application 79 28.899 filed 20 August 1979 the Applicant described a constantly circular rim, statically and dynamically balanced by the action of electromechanical means acting differentially on 120 the localised masses and this, from suitable detectors. It is an object of the present invention to provide a method consisting, in the first place, of constructing as an assembled structure, hence not one-piece, the hub-web which receives, in support, the wall of subcircular rim.

Such a method enables the application of a mass placed at the end of each web, such that the centrifugal force undergone by this mass counters the radial compressive force that this subcircular rim tends to exert on this rim, in the direction of the axis of rotation.

Besides this essential feature, the method according to the invention consists in the second place, of statically and dynamically balancing the subcircular rotor by the fact of the action of means acting differentially on the masses this from suitable detectors.

In the third place, the method according to the invention provides for distributing between the webs, the pressure exerted by said rim to reduce the fatigue of the material with which it is constituted. Elastic support means may be provided for this purpose between the subcircular rim and the webs.

Other features and advantages of the present invention will emerge from the description which follows, given with reference to the accompanying drawings, of preferred embodiments to be taken purely as non-limiting examples.

Brief Description of the Drawings 90 In the drawings: Figure 1 is a diagrammatic view in partial radial section showing the behavior of a design of inertia wheel with a thick rim, on webs forming a light onepiece unit with the hub; 95 Figure 2 is a diagrammatic view in partial radial cross-section of a rotor according to the present invention; Figure 3 is a partial perspective view showing a possible arrangement of the various elements for the application of the invention in an inertia wheel; Figure 4 is a view in partial axial section along the line of IV- IV of Figure 3; and Figure 5 is a perspective view with parts torn away, of a modification of the embodiment of a rotor according to the invention.

Description of Preferred Embodiments

The principle itself of subcIrcularity derived from the aforesaid French patent N 70 08394, is reviewed with reference to Figure 1.

A subcircular rotor includes hence essentially a one-piece unit formed from a core 3 fast to webs 2 as well as to a wall 1 A of a rim applied to said webs but in a conformation according to which the portions of wall between the webs remain constantly subcIrcular, that is to say within the circle passing through the tops of the webs along the radius R and beyond a limit close to a polygon defined by these same tops.

On rotation, the force F (which normally results from the expression 2a cos a in which, for a given rim cross-section, or represents the allowable tensile stress of the constituent material of the rim and a the angle formed by each wall tangent in line with each web) is variable, radial and directed towards the axis of rotation XX.

Thus, when the rotary speed increases, the 2 GB 2 054 094 A 2 angle (z tends toward a=90 whilst its cosine decreases, resulting for this reason in a variation of the force F until it reaches moreover theoretically, a nil value on circularity and, in this 5 case, the web- rim bond is no longer ensured.

As has been previously mentioned, when each radial force F exerted by the wall 1A against each web 2 is relatively weak through the fact of the rim being of little thickness, the webp_May be thin since the compressive forces to be withstood are of small magnitude.

On the other hand, when the subcircular rim becomes large in an inertia wheel configuration, the radial forces F also become large, which requires each web to be constructed to withstand buckling (shown along the arrow f in Figure 1), and the webs must consequently have a construction of massive aspect such as that shown in interrupted lines in this same Figure 1.

Such an adaptation of a hub-web one-piece unit does not permit optimisation of the inertia wheel to the extent that this unit is necessarily bulky and difficult to machine if some lightening is sought.

In addition, static and dynamic balancing of inertia wheels of this type is delicate if not impossible to carry out in the course of rotation since the wall 1 A of the rim 1 is applied to the webs 2 fast themselves to their hub 3.

Finally, the aimost punctual support of the wall 1 A against the webs results in the compressive forces existing in the rim are poorly distributed between the webs, whence considerable fatigue of the constituent material of said rim; which fatigue is accentuated by the alternating flexions resulting from the variations in rotary speed. The construction of a subcircular rotor according to the invention enables all these drawbacks to be overcome. 40 In addition, inertial wheels thus optimised in their performance can advantageously be applied conjointly with effective magnetic suspension means and with particular electro-magnetic means for driving and restoring energy in electrical form.

In accordance with Figure 2, the invention consists, essentially of a first means marked 100 as a whole, enabling the radial stresses in each web of the subcIrcular rotor to be reduced, a second means marked 200 as a whole enabling the balancing of the rotor in the course of rotation 115 and a third means marked 300 as a whole enabling the compressive forces to be distributed in the rim between each web According to this Figure 2, each web is no longer fast to the hub 3 but is supported against a 120 bushing 102, itself fast to the hub 3, whilst appended axial guide means are provided through the radially slotted flanges 104 and 105. The radial guide means result from an axial groove formed in the bushing itself 102.

Each web can be either formed in a thin wall in the central portion of the rotor and include an extension of its mass towards the outer part, or constituted of several separate elements, such as for example a central element 10 1 and a terminal element 103, without the principle itself of the invention being however affected, the condition sine qua non being that each web is not fast to the hub as a whole.

This principle arises from the fact that the masses of the web act, through their own centrifugal force F' =M 2 r, so as to be subtracted from the compressive forces coming from the subcircular rim 1.

In a way and through the fact of convenient adjusting of the term F-P, it is possible to determine the resulting urging force on each web, which may be very much reduced and lead to webs of small thickness; it being understood that these webs must however be dimensioned to enable the application of the rim in the absence of rotation.

Through its second means marked 200, the invention permits balancing of the rotor through the fact of the action of an electromechanical mechanism acting on elements connected to the webs by pushing or pulling the latter differentially.

By way of example, Figure 2 shows an electromechanical mechanism pushing on the webs differentially.

In the central portion of the hub 3 is arranged a tangential wheel 203 driven by a worm screw 202 coupled to a motor 204 and this wheel receives a threaded element 201 whose radially center ends on the hub are supported against the web 10 1 and the web opposite it.

A balance detector of any known type shown diagrammatically at 205 acts on the motor 204 to determine the value and the direction of rotation of the tangent wheel 203.

Thus, according to the signals received from the detector 205 the motor 204 enables the movement in one direction or the other of the element 201, which, correlatively, pushes one or the other of the webs against which it is supported.

Of course, it is possible to adopt a reverse configuration which produces moreover an identical result and according to which the element 201 is hooked after each web so that it is the effects, by pulling, which produce this time the desired result.

In other words, the electromechanical mechanism housed towards the rotary axis XX' allows the escape, in one direction or the other, of an element connected to two opposite webs, so that the resulting differential action, whether by pulling or by pushing, leads to the desired balance.

A similar action on all the pairs of webs and in their axial end portions is of course necessary to arrive at complete balancing of the rotor along the rotory axis X-X'.

As a modification, the element 201 which is a] [owed to escape in one direction or the other can, without acting directly on the webs and by simple displacement, constitute, in itself, the desired balancing means, as will be seen in detail i i 3 GB 2 054 094 A 3 1 50 with reference to Figure 5 showing an embodiment of the invention.

According to a third means marked 300, in Figure 2, the invention enables distribution over a larger surface and between each web, of the compressive forces which exist in the rim. To this end, an elastic blade 301 whose edges 9 will have been raised is interposed between the rim 1 and each web which enables, at the same time, distribution of the compressive forces by increasing the load on the inner layers, so as to reduce the radial stresses which develop there.

The embodiment shown in Figures 3 and 4 is representative of a design of subcircular rotor in accordance with the invention and according to which said rotor is constituted by a modular unit. If necessary a group may be constituted by a stack of modular units to constitute, for example, a long rotor in the direction of the rotary axis XX'. 20 In Figure 3, the subcircular rotor in accordance with the invention includes essentially a rim 10 supported by its wall 1 OA against the webs referenced 12 as a whole; said webs in any number but two as a minimum, are in this themselves constituted by a solid terminal element 12 A set in by a tenon-mortice joint in a central element 12B, and the webs are supported against a bushing 16 connected by any suitable known means to the hub 3.

Bushing 16 is stopped axially by rings 17 and 18 gripping the flanges 13 and 14 to enable the transmission of torques between hub and rim, whilst the webs are held by bevel shoulders formed on the one hand in axial groove 16A of the bushing 16, and, on the other hand, in radial 100 grooves 13A-1 4A formed in the flanges 13 and 14.

Flanges 13 and 14 may include lightening recesses and subcircular winding 15 and 19 can permit them to withstand the centrifugal force 105 which is applied to them.

The compressive force distributing elastic means are represented by elastic blades 11, interposed between the wall 1 OA and the webs 12.

Figure 4 shows essentially how the central element 12B of each web 12 can include a transverse complementary lightening in the form of a recess 12C.

Of course, these central elements could be broken into simpler elements so as then to constitute an assembly into a structural set, with the rim, the end portions of the webs or again elastic support means of the rim on said webs.

Such a modular design permits, for example, the application of the invention in numerous fields ranging from small units for the storage and recovery of energy on a satellite up to large electrical energy regulating installations in supply systems.

It is self-evident that the number of webs with a minimum of two and their shape, the type of connection of the latter to the bushing and the type of integration of the masses, the constitution of elastic means, the design of the mass of the subcircular rim or its shape or the nature of its constituent materials, whether they are of homogeneous or heterogeneous nature (filiform, lamellar in coiled or superposed layers including any suitable materia) may be adapted as a function of the circumstances, to the extent that the expected result of the invention is obtained.

It has been seen previously that the balancing of the rotor might be obtained by acting differentially on the balancing element from data derived from detectors.

More particularly, it has been seen, with reference to Figure 2, that the balancing system can act directly on the webs, by pulling or pushing; it could also act in traction without however acting directly on the webs.

In addition, it has been seen, with reference to Figures 3 and 4, how a rotor according to the invention could be constituted of modular units enabling the application of the invention in numerous fields.

There will now be described, with reference to Figure 5, another possible modification of the invention which has certain significant advantages among which may be mentioned that it enables the constitution of a hub-web system: which is as light and economical as possible; which minimises static and dynamic unbalance; which is compatible with the passage in its center of an axle or hub which is generally necessary when the rotor is associated with a magnetic suspension and with a generating motor; which facilitates the constitution of modular units.

The hub-web system concerned is formed from two webs or radial arms denoted by the general reference numbers 20A and 20B and constituted by cruciform caissons.

More precisely, they comprise longitudinal members 2 1 A 22A for one and 21 B, 22B for the other. These members are hollow and their height in the central area where they cross is one half of their height on the outer portions. On the other hand, the thickness of these members is increased in the central zone where their height is reduced so that the elements constituting the caissons have a constant cross-section in spite of the crossing of the arms.

In addition, the longitudinal members 2 1 A, 22A on the one hand, and the longitudinal members 21 B, 22B on the other hand, are held relative to forces that they undergo in directions perpendicular to their respective lengths by cruciform plates such as 23 and 24, the first one being shown partially. In order to reduce the longitudinal stress in the central zone, the crosssection of the plates can be widened in this zone as shown at 25.

Four masses 26, 27, 28, and 29 are localised, in accordance with the invention, at the respective ends of the radial arms 20A and 20B. These masses may advantageously include a radial extension such as 30, which enables the mass of the rim 10 whose height corresponds to the modular element thus formed to be supported.

4 GB 2 054 094 A 4 It is obvious that the modular elements of the same nature are stacked to constitute a complete rotor, the connection between the various elements being effected, for example, by glueing, which is particularly suited to the utilisation of composite materials such as glass resin, keviar resin, carbon resin etc.

When thC. modular element also constituted by these cruciform arms is of composite materials of the wire or filament type (like that appearing notably in the torn-off portion reference 31 of the longitudinal member 22B for example), all conventional processes for the application of conventional materials are obviously applicable and in particular, layer up or winding to constitute the longitudinal members, the plates and the complementary parts.

It is obvious, moreover, that when the plates such as 23 and 24 are pierced to allow the hub 3 to pass through, the flanges surrounding the whole may be reinforced by glueing or suitable fixing of an element as an overthickness to constitute the constant cross-section.

It will be apparent immediately from Figure 5 that the end masses 26, 27, 28 and 29 may be wider than in the preceding embodiments due to the constitution of the radial arms as a caisson and may have also a greater support surface and consequently ensure better distribution between the arms of the pressure exerted by the rim 10. Clearly, these end masses may also include elastic complementary lateral plates 11, as in the preceding embodiments.

Of course, the shape of these masses is defined so that, at the maximum rotary speed, the centrifugal force F' of the support mass concerned, 27 for example, substantially balances the resultant F of the forces applied by the rim 10 on said mass 27 and corresponding arm 20A. In any case, the term F-F' is adjusted so that the resulting force from this difference is directed towards the axis XX' and so that the rim-web-hub assembly is firmly fastened and constitutes a unit of great rigidity.

As regards the balancing of the rotor, there is shown diagrammatically in Figure 5 a possible principle of construction with a cruciform arm rotor such as has just been described.

Due to the boxed form of the arm 20A and 2013, and the presence of the hub 3, it is possible to connect support masses 26, 27, 28 and 29 by respective cables 32 for the mass 26, 23 for the mass 27, 34 for the mass 28 and 35 for the mass 29 to a control device, of any known type denoted by the general reference 36 capable of acting differentially in traction on one or other of the masses 26 or 27 of the arm 20A for the cables 32 or 33 and, on one or other of the masses 28 or 29 of the arm 20B by the cables 34 or 35. But of course, balancing detectors of any known type of which one is shown diagrammatically at 205, provide the necessary data to the control device 36 so that the latter may act, as a function of said data, differentially on the opposite masses 26 and 27 of the arm 20A and on the opposite masses 28 and 29 of the arm 20B so that the balancing of the whole of the rotor is achieved dynamically.

In general, the invention has only been described and shown byway of preferred example and equivalents could be introduced into its constituent elements without however departing from its scope, which is defined in the appended claims.

Claims

1. Method of constructing a rotor of the subcircular type comprising an axial central hub, webs or radial arms and a rim supported on said webs whose radius of curvature of the sectors between two consecutive webs is higher than the outer radius of said webs, said method consisting- of dissociating the hub-web system receiving in support the wall of said subcircular rim; of localising the mass of said webs towards the rim; and of causing the centrifugal force which arises from the rotation of each mass of said webs to act in deduction of the radial compressive force exerted by the rim towards the rotary axis; whereby the radial stresses exerted by said compressive forces in each web are reduced.

2. Method according to claim 1, wherein each web is dissociated into at least two elements, one central the other terminal, said terminal element then constituting the major part of the mass of the web.

3. Method according to claim 1 or 2, wherein the dynamic balancing of the rotor is assured by acting differentially on the masses, from data obtained from detectors.

4. Method according to any preceding claim, wherein the pressure exerted by the rim is distributed between the webs by increasing the support surface on each web and by rendering it elastic.

5. Method according to any preceding claim, wherein the set of webs is of modular design enabling its application from small units for the storage and the recovery of energy on a satellite to large installations for regulating the electrical energy in distribution networks.

6. Subcircular type rotor applying the method of construction defined in claims 1 to 5 comprising- an axial central hub; radial webs or arms assemled to said central hub to be supported thereon; masses localised at the outer ends of said webs and constituting thereof the major part of the total mass of each; and a rim supported on said webs whose radius of curvature of the sectors between two consecutive webs is higher than the outer radius of said webs; the size of said localised masses being adjusted so that the centrifugal force that they undergo, in the course of the rotation of the whole, is deducted from the radial compressive force that the subcircular rim exerts, when i -9 k GB 2 054 094 A 5 stationary, on each web, in the direction of the rotary axis.

7. Subeircular type rotor according to claim 6, wherein each of the webs is constituted by a central element and a terminal element connected together, the central elements of the webs being supported on the hub grooved axially for this purpose and immobilised by radially grooved end flanges and connected to the hub.

88. Subcircular type rotor according to claim 7, wherein the grooved immobilising flanges of the webs are lightened and include a subcircular 40 winding to withstand the effects of the centrifugal force.

9. Subcircular type rotor according to claim 7, wherein a balancing system is arranged in the hub, which includes per pair of opposite webs a 45 tangent wheel-wormscrew assembly acting on a threaded element actuating the central elements of the webs differentially from data received from detectors.

10. Subcircular type rotor according to claim 6, 50 wherein the set of webs if formed, on the one hand, by two arms crossing of which is constituted by two hollow longitudinal members crossing along a constant cross-section with the longitudinal members of the other arm, on both sides of the hub, said longitudinal members being covered laterally in the axial direction with cruciform plates, and on the other hand, by four masses localised at the respective ends of the two arms, the assembly of the webs forming a modular unit.

11. Subcircular type rotor according to claim 10, wherein modular units constructed of composite materials of the thread or filament type are stacked on one another and connected together by glueing.

12. Subcircular type rotor according to claim 10, wherein a balancing system is constituted by connecting cables connecting each of the masses, through the caissoned arms and the hub, to a differential control device sensitive to data received from detectors.

13. Subcircular type rotor according to claim 9 or 12, wherein elastic elements are intercalated between the rim and each mass to constitute the method of distributing the pressure of the rim on the webs.

14. Method of constructing a subcircular type rotor, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

15. Rotor of the subcircular type whenever constructed according to the method of claim 14.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.