The present invention relates to an energy accumulator, specifically for use in an elevator installation or in relation to other discontinuous or intermittent "loads", such as machine tools.

More specifically, the invention relates to an energy accumulator including:

a support envelope made of a thermally conductive material, particularly a metal, containing

a reversible electric machine including a stator attached to said envelope and a rotor with permanent magnets that is mounted rotatably with respect to the stator, and

a flywheel mass constrained to rotate with the rotor of said electric machine.

An elevator installation including an energy accumulator of mis type is described in international patent application WO 2009/156953 A1.

Such an accumulator is able to store kinetic energy that is known to be proportionate to the moment of inertia of the flywheel mass in relation to the axis of rotation and to the square of the angular velocity.

In various applications, such as elevator installations, flywheel energy accumulators are used instead of batteries or capacitors on account of their ability to release a large amount of energy in a very short space of time (very high specific power), and of the improved ratio between energy capacity and mass, compared to chemical batteries.

One objective of the present invention is to provide an energy accumulator of the type specified above, with innovative characteristics.

This and other objectives are achieved according to the invention using an energy accumulator of the type defined above, in which:

the assembly formed by the rotor of said reversible electric machine and the flywheel mass is mounted rotatably about a fixed shaft, which extends inside said support envelope; and

the ends of said shaft are coupled with the support envelope by respective vibration- damping support devices, each having an inner annular support, made at least in part of a thermally conductive material, mounted in an outer bearing member made of resilient material, attached to said envelope;

each inner support member being thermally coupled with the support envelope by at least one thermal transmission member, such that, when in operation, the heat generated in said assembly and in the support member is transmissible to said envelope through the at least one transmission member.

In one embodiment, the shaft is operationally horizontal and each support device comprises a stop member against which the corresponding descending inner annular support can be stopped in case of yielding of the related resilient bearing member. Further characteristics and advantages of the invention are set out in the detailed description below, provided purely as a non-limiting example, with reference to the attached drawings, in which:

Figure 1 is a perspective view of an energy accumulator according to the present invention;

- Figure 2 is an exploded perspective view of the energy accumulator in Figure 1 ;

Figure 3 is a perspective view of part of the energy accumulator in the preceding figures;

Figure 4 is an exploded perspective view of part of the energy accumulator shown in Figure 3;

- Figure 5 is a cross-section along the line V-V in Figure 3;

Figure 6 is an exploded perspective view of the part of the energy accumulator shown in Figure 5;

Figure 7 is a partial perspective view of the stator of the electric machine included in the energy accumulator in the preceding figures;

- Figure 8 is a partial exploded perspective view of part of the winding of the stator shown in Figure 7;

Figure 9 is a perspective view of the winding portions in Figure 8 in the mutually coupled state;

Figure 10 is an exploded perspective view of another part of the energy accumulator in the preceding figures;

Figure 11 is a cross-section along the line XI-XI in Figure 10;

- Figure 12 is a perspective view of the assembly formed by the rotor of the electric machine of the accumulator and the associated flywheel mass;

Figure 13 is a cross-section along the line XIII-XIII in Figure 12;

Figure 14 is a cross-section along the line XIV-XIV in Figure 1 ;

Figure 15 is a magnified view of part of Figure 14;

- Figure 16 is an exploded perspective view of a support device for the shaft about which the rotary mass of the accumulator rotates according to the preceding figures;

Figure 17 is a cross-section of the support device in Figure 16; and

Figure 18 is a perspective view of the support device in Figures 16 and 17. In the drawings, reference sign 1 indicates, as a whole, an energy accumulator according to the present invention.

The energy accumulator 1 includes a support envelope indicated as a whole using reference sign 2. As shown in particular in Figures 1 , 2, 14 and 15, the support envelope 2 in the embodiment illustrated includes two half-shells 3 and 4 made of a thermally conductive material, in particular metal, clamped against one another using bolts 5 and nuts 6.

As shown more clearly in Figures 3 to 6, the half-shell 3 is overall substantially basin- shaped, with an essentially circular mouth or aperture, around which there is a flange 3a that is essentially transversal to the axis A-A of the accumulator and designed to be coupled frontally with the corresponding flange 4a of the half-shell 4 (Figure 2).

The half-shells 3 and 4 of the support envelope 2 have appropriate respective pairs of lower appendices 3b, 4b acting as feet for bearing against an essentially horizontal support surface. With reference to Figures 3 to 6, the stator 7 of a reversible electric machine, i.e. one able to act as a motor and as a generator, is mounted in the half-shell 3 of the support envelope 2 (in a manner described in greater detail below). In the embodiment shown, this stator 7 is essentially ring-shaped overall and is mounted coaxially with the lateral wall 3c of the half- shell 3.

As clarified below, the stator 7 has a winding, for example a three-phase winding, the terminals of which are linked to connection terminals provided in a connection assembly 8 (Figures 4 and 7) rigidly connected to same.

This connection assembly 8 extends sealingly through and beyond a corresponding aperture 3d (Figures 1 and 2) formed in the back wall of the half-shell 3 of the support envelope 2. making same accessible from outside said envelope 2 for connection to an installation using the energy accumulator 1 , such as an elevator installation.

With reference in particular to Figures 2 and 14, a fixed shaft indicated using reference sign 9 is mounted between the two half-shells 3 and 4 of the support envelope 2.

The ends 9a of said shaft are inserted in respective vibration-damping support devices 10 mounted in respective seats 3e, 4e formed in the central zone of the back walls 3f, 4f of the half-shells 3 and 4.

A rotary mass indicated as a whole with reference sign 11 in Figures 2 and 12 to 15 is mounted rotatably about the shaft 9 between the two half-shells 3 and 4.

The rotary mass 11 includes an annular block 12 made of metal, with a central passage 12a in which the fixed shaft 9 is mounted, with interposed bearings 13.

The overall shape of the block 12 is essentially cylindrical and the end faces of same have respective circular annular grooves 12a and 12b.

There is an annular space, indicated using reference sign 14 in the drawings, between the ring of permanent magnets 43 and the radially innermost wall of the groove 12a.

As shown in Figure 14, the stator 7 extends inside said annular space 14, defining a thin minimum radial air gap with the magnets 43.

As shown in particular in Figure 14, the groove 12b is shallower than the groove 12a. The groove 12b does not need to be as large as the groove 12a since the latter is partially filled by the magnets 43 to ensure the correct balancing of the rotary mass (and in particular of the loads on the bearings 13).

With reference to Figures 2, 10 and 11, the flange 4a of the half-shell 4 has an annular groove 4g containing a toric sealing ring 15 held against the flange 3a of the half-shell 3. In these figures, reference sign 16 indicates a disc, for example made of a plastic or elastomer, positioned in a slight recess in the back wall 4f of the half-shell 4 of the support envelope.

The disc 16 has a central aperture 16a, which is circular in the example embodiment illustrated. A plurality of essentially radial and angularly equidistant notches 16b, of which there are four in the embodiment illustrated, extend from this aperture 16 (see in particular Figure 10).

Certain aspects and components of the energy accumulator 1 described above are described in greater detail below. With reference to Figures 3 to 9, and in particular to Figure 7, the stator 7 includes an annular bearing structure 17, for example made of moulded plastic.

This structure essentially includes a rear ring 17a (Figure 6) that extends in a plane substantially transversal to the axis A-A of the accumulator 1.

On the side oriented towards the half-shell 4, an outer ring 17b and an inner ring 17c (Figures 6 and 7). which are coaxial with one another and with the axis A-A when assembled, extend in a direction parallel to the axis A-A from the rear ring 17a of the structure 17.

In the embodiment shown, the rings 17b and 17c are essentially cylindrical and the axial length of the second ring 17c is greater than the axial length of the first ring 17b.

There is an annular seat between the rear ring 17a and the rings 17b and 17c in the bearing structure 17 in which two rings of spools 18A and 18B, respectively inner and outer, are partially inserted, in an axial direction, about which the windings of the stator 7 are wound.

The radially inner spools 18A extend along the outer surface of the cylindrical ring 17c.

The radially outermost spools 18B extend outside the spools 18A, which are preferably coupled mechanically in the manner described below with reference to Figures 8 and 9.

Each inner spool 18A has, in the middle circumferential zone of same, two pairs of projections 18a, aligned axially together in pairs (see in particular Figure 8).

The arrangement is such that the projections 18a of an inner spool 18A can be inserted into the adjacent hollows 18b of two adjacent spools 18B. The arrangement shown by way of example is such that, once assembled, the inner spools 18A are offset by one half pitch in relation to the outer spools 18B. The offset between the outer spools and the inner spools may moreover be other than one half pitch. Preferably, the number of spools 18A (18B) in each layer is equal to 3/4 of the number of permanent magnets 43.

As shown in Figures 8 and 9, the inner spools 18A are conveniently provided with respective pairs of hollows or recesses 18c in their radially innermost side of same. When the rotor 7 is assembled, the corresponding outer retaining projections 17e of the cylindrical ring 17c are engaged in said hollows or recesses 18c. In the embodiment, the inner and outer spools 18 A, 18B, already provided with respective windings of insulated electrical wire and interconnected using established means, are assembled on the annular bearing structure 17, as shown in Figure 7. An electrically insulating resin is cast or injected, using an appropriate mould, onto tfe spools 18A, 18B and onto the outer surface of the cylindrical ring 17c and into the gap formed between said spools and the outer ring 17b, such as to form a solid annuls structure 19 in the assembly (Figures 3 to 6). The stator 7 so formed is then attached to the back wall 3f of the half-shell 3 of the supprt envelope of the accumulator, for example using screws 20 and related bushings 21. these latter being preferably made of a resilient material (see also Figure 3).

With reference in particular to Figures 14 to 18, each support device 10 for the ends 9a of the shaft 9 has an inner annular support 30 made of a thermally conductive material, in particular a metal, in which an essentially cylindrical seat 30a is formed for the related extremity of said shaft 9.

In the embodiment shown (see in particular Figure 16), the inner annular support 30 has a gap 30b that extends in a direction essentially parallel to the axis of the cylindrical seat 30a. This gap 30b causes the inner support 30 to form two branches or prongs 30c and 30d that are adjacent to one another, but separate.

The inner annular support 30 of each support device 10 is inserted into a matching seat 3 1 a formed in an outer supporting member 3 1 made conveniently of a resilient material, for example an elastomer.

In the embodiment shown, the outer shape of the inner annular support 30 is essentially quadrangular. Correspondingly, the seat 31 a of the outer supporting member 31 is also substantially quadrangular.

In the embodiment shown in the drawings, the outer shape of the member 3 1 is also essentially quadrangular.

With specific reference to Figures 16 and 18, respective heat transmission members 33 and 34 are attached, using screws 32, to the flat upper faces of the prongs 30c and 30d.

In the embodiment shown, the transmission members 33 and 34 are essentially in the form of metal straps that, once attached (for example using screws) to the prongs 30c and 30d of the inner annular support 30, extend through corresponding recesses 31b formed in the top side of the seat 31a of the corresponding outer supporting member 31 made of resilient material.

When the energy accumulator 1 is assembled, the thermal transmission members 33, 34 of the support devices 10 are in close contact with the back walls of the half-shells 3 and 4 of the support envelope 2, such that the heat generated by operation in the rotary mass 11, as well as in the shaft 9, is liable to be transmitted to the support envelope 2 through said transmission members 33, 34, to be subsequently dispersed in the surrounding environment.

As shown more clearly in Figures 16 and 17, an essentially vertical through-hole 3 Id is formed in the lower horizontal branch 31c of each outer supporting member 31. A rod 35 made of a rigid material, for example a metal, is placed in said hole 31 d (see also Figures H and 15).

As shown in particular in Figure 15, the upper extremity of each rigid rod 35 faces and is vertically separated from, by a predetermined distance, the related support 30.

The rods 35 are advantageously intended to act as stopping members against which the supports 30 are liable to butt in the event of yielding of the resilient member 31 , under the action of the weight of the shaft 9 and of the rotary mass 11 as a whole.

The length of the rigid rods 35 is in fact determined such that the accumulator 1 can in any case work acceptably even after yielding of the resilient bearing members 31 , although without the damping action that these latter are able to provide under normal conditions.

Conveniently, the vertical thicknesses of the horizontal branches of the resilient bearing members 31 can be dimensioned such that when the energy accumulator 1 is initially commissioned, the axis of the shaft 9 and of the related rotary mass 11 extends vertically above the optimal design height, with a view to at least partially compensating in advance for the subsequent "descent" of said components due to progressive yielding (in particular of the lower horizontal branches) of the resilient bearing member 3-1 under the action of the weight acting on same.

Conveniently, means for sensing the rotary speed of the rotary mass 11, for example three Hall-effect sensors able to detect the passage of the permanent magnets 43 of the rotor 11 - 13, can be assembled in the connection assembly 8 (Figures 1 and 2). With reference again to Figure 15, a tubular element 40 constrained to rotate with the rotary mass 11 is arranged conveniently between the bearings 13.

The ends of this element 40, oriented toward said bearings 13, have respective essentially tapered surfaces 40a converging towards the axis A-A away from the half-shells 3 and 4 of the envelope of the accumulator.

Furthermore, shaped rings 42 are attached, in axially opposed positions and using screws 41 , in the block 12 of the rotary mass 11. These rings extend at least in part beside the bearings 13 on opposite sides in relation to the ends of the tubular element 40.

The shaped rings 42 in particular define respective essentially tapered surfaces 42a converging towards the axis A-A and the half-shells 3 and 4 of the envelope of the accumulator 1. The tapered surfaces 40a and 42a thus formed on the sides of each bearing 13 enable the splashes of grease or other lubricant to reach the devices for which they are intended, said lubricant tending to be "centrifuged" in operation under the effect of the rotation at high angular speed of the rotary mass 11.

In operation, the energy accumulator according to the present invention generates a low- intensity acoustic noise. Complete elimination of the noise generated can be achieved if the energy accumulator is mounted in a container or a hole filled with sand or another sound damping material.

Naturally, notwithstanding the principle of the invention, the means of implementation and the specific embodiments may vary greatly from that described and illustrated purely by way of a non-limiting example, without thereby moving outside the scope of the invention as defined in the attached claims.