Improved electronic motor

Abstract

An improved electronic motor (1) comprises a hollow, tubular motor body (2); a rotor (3) provided with a shaft (4) housed coaxially in the motor body (2), as well as a disk (5) keyed onto the shaft (4), placed in an intermediate position between ends (6,7) of the shaft (4) and carrying magnets (8); supports (9) for supporting the shaft (4) on the motor body (2) comprising rotatable thrust bearings (10); and inductors (12) with relative energising electronic circuitry (21) which is interactive with the magnets (8). The thrust bearings (10) are provided with hubs (13) equipped with inner teeth (14) couplable: rigidly in a direction twisting relative to the axis (11) of the rotor (3) with outer teeth (24) shaped to match them carried by the ends (6,7) of the shaft (4), and in contrast with freedom to oscillate angularly and freely in an axial plane of the rotor (3) to automatically compensate for any axial misalignments between the shaft (4) and thrust bearings (10).

Description

[0001] IMPROVED ELECTRONIC MOTOR

[0002] Technical field

[0003] This invention relates to an electronic motor with a hollow shaft operating with axial electromagnetic flux.

[0004] Background art

[0005] The technology of electronic motors already involves hollow-shaft motors operating with axial electromagnetic flux.

[0006] The hollow shaft allows these motors to advantageously be used in many and varied technical fields which, for example, range from robotics, in which the hollow shaft facilitates, amongst other things, device wiring; to linear movement, in which the hollow shaft favours the construction of actuators with simpler design and smaller overall dimensions, compared with the more conventional technique; to transmissions of motion of some electrically propelled means of transport, such as for example bicycles, in which the hollow shaft allows simplification of the construction, reduction in the number and dimensions of component parts and improvement in functional performance.

[0007] The functional performance of such hollow shafts is significantly affected by the mechanical quality of the machining of the component parts thereof. As the mechanical quality increases so too do the costs of the product, meaning that the highest performance electronic motors are also the most expensive.

[0008] Disclosure of invention

[0009] The main aim of this invention is to devise an embodiment of an electric motor with hollow shaft, operating with axial electromagnetic flux, where the construction and industrialisation of that motor are designed to be practically completely implementable with additive material manufacturing technologies, such as for example, sintering, digital printing, die-casting and the like.

[0010] Such a technical set-up, involving the practically complete elimination of stock removal by mechanical machining, would in fact allow a considerable reduction in motor machining costs and a considerable saving in terms of the materials used to make the motor, however provided that a way can be found to maintain an operating effectiveness at least comparable to that of the highest technological quality prior art solutions.

[0011] In accordance with that aim, the invention therefore intends to provide such a solution which may be significantly less expensive, without thereby having to give up the performance and effectiveness found in much more expensive prior art solutions made with high precision and quality mechanical machining operations.

[0012] In accordance with the invention, such a solution is implemented by a hollow-shaft electronic motor, with axial electromagnetic flux, as defined in the claims below.

[0013] Brief description of drawings

[0014] The features and advantages of the invention will be apparent from the detailed description of a preferred embodiment of the motor with reference to the following figures in which:

[0015] - Figures 1 and 2 are two perspective views of the invention, shown from the front and rear, as seen from two different viewing angles;

[0016] - Figures 3 and 4 are respectively a front view and a side view of the invention of Figures 1 and 2; - Figures 5 and 6 are two axial sections of the motor according to the invention;

[0017] - Figure 7 is a partial view, of a detail of Figure 6, enlarged to better illustrate some specific technical features thereof;

[0018] - Figure 8 is a perspective view of a first component of the motor, exploded, enlarged, and with some parts cut away to better illustrate others;

[0019] - Figure 9 is a perspective view of a second component of the motor, exploded, enlarged, and with some parts cut away to better illustrate others;

[0020] - Figure 10 is a perspective view of a detail of the component of the motor shown in Figure 9;

[0021] - Figure 11 is a front view of the motor showing the line XII-XII of an axial section plane;

[0022] - Figure 12 is a view of the axial section of the motor according to the line XII-XII of Figure 11;

[0023] - Figure 13 is a view of a detail, in cross-section, of Figure 12, shown enlarged;

[0024] - Figures 14, 15 and 16 are, respectively: a front view, an axial section, and a perspective section of a driving thrust bearing of the motor according to this invention;

[0025] - Figures 17, 18 and 19 are a front view, an axial section, and a perspective section of a supporting thrust bearing of the motor according to this invention;

[0026] - Figure 20 is an enlarged view of a detail of the invention;

[0027] - Figures 21 and 22 are, respectively, an exploded view of schematic electric circuitry inside the motor, and a view of the same circuitry assembled;

[0028] - Figure 23 is an overall view which illustrates the electric circuitry of Figures 20 and 21 connected to field coils of the motor and shown with some parts of the invention cut away to better illustrate others;

[0029] - Figure 24 is a perspective view which illustrates a particular way of making a structural interconnection between component parts of the invention;

[0030] - Figures 25 and 26 are views illustrating a method of serial interconnection of motors according to this invention.

[0031] Preferred embodiments of the invention

[0032] With reference to the figures of the accompanying drawings, Figures 1 to 4 show an improved electronic motor (1), preferably of the brushless type, which basically comprises: a motor body (2), placed inside of which there is a rotor (3); rotor supports (9); a series of electromagnetic inductors (12); and electric circuitry (21).

[0033] More specifically, (Figures 5 and 6), the motor body (2) has a substantially tubular, cylindrical shape, closed at its opposite ends by two end supports (9).

[0034] The rotor (3) is provided with a shaft (4) -preferably hollow, with tubular shape - housed inside the motor body (2) in a position coaxial with the motor body.

[0035] The rotor (3) is provided with a disk (5), which is keyed onto the shaft (4), is placed in an intermediate position between toothed ends (6, 7) of the shaft (4 ), and carries a plurality of magnets (8), distributed in angular steps along circular sectors of the disk (5) of the rotor (3), and simultaneously facing out from the two opposite faces of the disk (5).

[0036] The magnets (8) are fixed to the disk (5) preferably being set in it by overmoulding, with retaining in position of the interference type, obtainable by means of the presence of an undercut (36) made on the outline of the magnet (8) as shown in Figure 10.

[0037] The supports (9) for supporting the shaft (4) have a complex, multi-purpose structure which, firstly, comprises thrust bearings (10) rotatable around an axis (11) of rotation of the rotor (3).

[0038] One of the thrust bearings (10) is devised to act as a power take off and, as such, may be provided with feed holes (35) provided for the transmission of torque from the shaft (4) to an external user, not shown in the drawings.

[0039] Present inside the motor body (2) there is a series of magnetic inductors (12), which are preferably distributed along two circular paths, which are closed in a ring, on either side of the disk (5) and appropriately opposite the magnets (8) carried by the disk (5).

[0040] The magnetic inductors (12), when appropriately electrically energised, allow, in combination with the magnets (8) of the disk (5), the creation of a magnetic field with axial flux which drives the rotation of the shaft (4) around its axis (11).

[0041] As can be inferred from Figures 5 and 6, and even better from Figures 9, 11, 12 and 13, the thrust bearings (10) are provided with hubs (13) equipped with inner teeth (14) which are rigidly couplable - in a direction twisting relative to the axis (11) of the rotor (3) - with the opposite ends (6, 7) of the shaft (4) which for that purpose are provided with outer teeth (24); the thrust bearings (10) and the ends (6, 7) of the shaft (4) are in contrast couplable at the same time with freedom to angularly oscillate in an axial plane of the rotor (3) in such a way as to automatically compensate for any misalignments which might occur, during actual operation of the motor (1), between the axis (11) of rotation of the shaft (4) and the axes (11) of rotation of the thrust bearings (10).

[0042] The technical effects described above are preferably obtained by assigning: to the inner teeth (14) of the thrust bearings (10), a spherical involute "spline" profile; and to the outer teeth (24) of the ends (6, 7) of the shaft (4), a conical involute "spline" profile.

[0043] In use, as is clearly shown in Figure 12, the shaft (4) and the thrust bearings (10) have teeth (24, 14) profiled in such a way as to cause automatic alignment of the rotor (3), through small relative oscillations, rolling around three centres (C1, C2, C3) of rotation, which are aligned, which define a kinematic chain that is unstable under a condition, said condition being caused by shape errors implemented, in actual use, in the effective united contact surfaces of the teeth (14, 24) of the thrust bearings (10) and of the shaft (4).

[0044] Clearly, the automatic alignment system described above also operates correctly in cases of components with precise dimensions and / or with contact surfaces finished off with mechanical machining.

[0045] Figure 5 and 6, and even more clearly Figures 7 and 8, show that the motor (1) comprises two multi-polar stators (15) provided with a disk-shaped body (25), in the form of an annulus, housed inside the motor body (2 ). Each disk-shaped body (25) is equipped with a first face (26) directed towards the supports (9) at the ends (6, 7) of the shaft (4), and a second face (27) directed towards the magnets (8) of the disk (5) of the rotor (3).

[0046] The second face (27) of the disk-shaped body (2) of the stators (15) carries a plurality of elongate cores (16) which project, longitudinally to the motor body (2), cantilever-style towards the disk (5) of the rotor (3) and which are suitable for supporting said series of inductors (12), in a ring, and opposite the magnets (8) of the disk (5) of the rotor (3).

[0047] Figure 7 shows, in particular, how the supports (9) at the ends (6, 7) of the motor shaft (4) also comprise flanged covers (17), placed to close the motor body (2) and resilient means (18), which are placed between each cover (17) and a corresponding first face (26) of the diskshaped body (25) of the multi-polar stators (15).

[0048] Those resilient means (18) are preferably in the form of elastic rings " OR", housed in suitable seats (42 ) of the multi-polar stator (15), which, due to their elasticity, are suitable for automatically compensating for any shape errors which might arise between the supports (9) and the multi-polar stators (15).

[0049] As can be inferred from Figures 1-4, the flanged covers (17) and the motor body (2) have peripheral edges (28, 29), adjacent to each other, which are shaped to match each other in such a way as to make bevelled structural interconnections with each other.

[0050] For those purposes, the tubular body (2) and the flanged covers (17) are equipped - preferably and as shown in Figure 20 - with tenons (19) and pockets (20) suitable for supplying, both axial stopping, and radial engagement, between said tubular body (2) and said flanged covers (17).

[0051] As already indicated, the motor (1) comprises electric connecting circuitry (21) for the inductors (12), which includes two annular circuits (30, 31), connected by transversal bars (32) oriented longitudinally to the motor body (2). The bars (32) may be in the form of printed circuits, flat cables, axial pin connections, and so on.

[0052] The entire circuitry (21) is housed inside the motor body (2), being supported there by the multi-polar stators (15).

[0053] Regarding the structure of the supports (9), the motor (1) also has physical integration of bearings, preferably rolling bearings, obtained by placing a series of rolling bodies (39) on tracks (40) made in combinations between the thrust bearings (10) and the flanged covers (17), as shown, for example in Figure 15.

[0054] Bearings made in such a way - directly between rotating thrust bearings (10) and flanged covers (17) -also have the further advantage of being able to work maintenance-free when the cover (17) and thrust bearings (10) are made of self-lubricating sintered material.

[0055] Returning to the circuitry (21), it can be seen from Figure 1, how said circuitry (21) carries polar ends (23a, 23b) jutting cantilever-style, and projecting longitudinally, from the first face (26) of the disk-shaped body (25) of the stators (15), then coming out towards the outside via suitably shaped through openings (41), made along the perimetric edge (28) of the flanged covers (17).

[0056] As a consequence of that it is possible to identify, inside the tubular body (2) an electric power unit (22) -shown as a whole in Figure 23 - in which the polar ends (23a, 23b) are such that they allow axial serial connection of multiple units (22) in such a way as to obtain motor (1) configurations which have different electric power, wherein the electric power is variable according to multiple series of a basic power.

[0057] That way of connecting highlighted in Figure 24, shows, in the schematic view of Figure 25, a motor (1) according to the invention for example formed by three units (22) which are axially connected to each other.

[0058] Figure 25 also allows an understanding of the usefulness achieved thanks to the particular geometric shape of the peripheral edges (28) of the flanged covers (17) and which consists of the immediate possibility of recognising the correct relative positioning to be assigned to each unit (22) in the sequence of units (22) regarding the configuration of the motor (1) to be assembled, said possibility being guided by the shape of the edges (28) of the flanged covers (17).

[0059] Another important aspect of the above-mentioned edges (28) is that of also making the internal electrical connections always visible from the outside of the motor (1); which allows motor (1) electrical serial connection with a simple "plug and play" action. Connectors (33) -housable inside the openings (41) due to the fact that they are shaped to match edges (28) of the covers (17) -are provided in order to give continuity to the ends (23a, 23b) in the areas of transition from one unit (22) to another, as shown in Figure 26.

[0060] Similarly to the electrical continuity of the circuitry (21), a similar continuity, but in this case mechanical, may also be established for the hollow shafts (4) (to be considered present inside the unit (22) of Figure 23) and not shown there.

[0061] Such a mechanical connection is made possible by the presence on the opposite ends (6, 7) of the shaft (4), of coupling means (34) with front teeth (35a) and compartments (35b), which are shaped to match each other according to the line of the axis (11) of rotation, and which can penetrate each other, longitudinally to the axis (11) of rotation of said shafts (14), as shown in Figure 25.

Claims

CLAIMS1. Improved electronic motor comprisinga motor body (2), with substantially tubular shape; a rotor (3) provided with a shaft (4) housed in the motor body (2) in a position coaxial with it, said rotor (3) being provided with a disk (5) keyed onto the shaft (4), placed in an intermediate position between ends (6, 7) of the shaft (4) and carrying a plurality of magnets (8);supports (9) for supporting the shaft (4) on the motor body (2) comprising thrust bearings (10) rotatable around an axis (11) of rotation of the rotor (3); and magnetic inductors (12) with relative energising electronic circuitry (21) which is interactive with said magnets (8);said motor (1) characterised in that said thrust bearings (10) are provided with hubs (13) equipped with inner teeth (14) couplable: rigidly, in a direction twisting relative to the axis (11) of the rotor (3), with opposite outer teeth (24) carried by the ends (6, 7) of the shaft (4); and with freedom to oscillate, in contrast, angularly and freely, in an axial plane of said rotor (3), in such a way as to automatically compensate for any axial misalignments which might occur between the shaft (4) and the thrust bearings (10).

2. Motor, according to claim 1, characterised in that the inner teeth (14) of said thrust bearings (10) have a spherical involute "spline" profile, the outer teeth (24) of said ends (6, 7) of the shaft (4) in contrast having a conical involute "spline" profile.

3. Motor, according to claim 1 or 2, characterised in that said shaft (4) and said thrust bearings (10) have teeth (24, 14) profiled in such a way as to cause automaticalignment of the rotor (3), through small relative oscillations, rolling around three centres (C1, C2, C3) of rotation which are aligned defining a kinematic chain that is unstable under a condition, said condition being caused by shape errors implemented in the united contact surfaces of the teeth (14, 24) of the thrust bearings (10) and of the shaft (4).

4. Motor, according to claim 1, characterised in that it comprises two multi-polar stators (15) provided with a disk-shaped body (25), in the form of an annulus, housed inside the motor body (2), said disk-shaped body (25) being equipped with a first face (26) directed towards the supports (9) at the ends (6, 7) of the shaft (4), and with a second face (27) directed towards the magnets (8) of the disk (5) of the rotor (3), said second face (27) of the disk-shaped body (2) of the stators (15) carrying a plurality of elongate cores (16) which project, longitudinally to the motor body (2), cantilever-style towards the disk (5) of the rotor (3) in such a way as to support said series of inductors (12) in a ring and opposite the magnets (8) of the disk (5) of the rotor (3).

5. Motor, according to claim 4, characterised in that said supports (9) at the ends (6, 7) of the motor shaft (4) comprise flanged covers (17), placed to close the motor body (2), and resilient means (18) placed at least between a said cover (17) and a first face (26) of the disk-shaped body (25) of the multi-polar stators (15), to automatically compensate for any shape errors which might exist between said supports (9) and said multi-polar stator (15).

6. Motor, according to claim 5, characterised in that said resilient means (18) comprise at least one elastic ring housed in a seat (42) interposed between at least oneof said covers (17) and a corresponding disk-shaped body (25) of a multi-polar stator (15).

7. Motor, according to claim 1, characterised in that at least said disk (5) and said magnets (8) of the rotor (3) are formed in a single body.

8. Motor, according to claim 5, characterised in that said flanged covers (17) and said motor body (2) have peripheral edges (28, 29), adjacent to each other, which are shaped to match each other in such a way as to make bevelled structural interconnections with each other.

9. Motor, according to claim 8, characterised in that said bevelled structural interconnections are made between said tubular body (2) and said flanged covers (17) by means of tenons (19) and pockets (20) suitable for supplying axial stopping and radial engagement between said tubular body (2) and said flanged covers (17).

10. Motor, according to claim 1, characterised in that said electronic circuitry (21) comprises annular circuits (30, 31), connected by transversal bars (32) longitudinal to the motor body (2), said circuitry (21) being housed inside said motor body (2) and being supported there by the multi-polar stators (15).

11. Motor, according to claims 1 and 5, characterised in that said supports (9) for supporting the shaft (4) include bearings with relative movable, united surfaces, which are integrated in the structures themselves of the thrust bearings (10) and of the flanged covers (17).

12. Motor, according to claim 10, characterised in that said circuitry (21) carries polar ends (23a, 23b) jutting cantilever-style, and projecting longitudinally, from the first face (26) of the disk-shaped body (25) of the stators (15), in such a way as to define an electric power unit(22), with modular structure, confinable inside said tubular body (2), said polar ends (23a, 23b) allowing coupling in axial continuation of a further power unit (22) to allow the creation of configurations of said motor (1) which have variable electric power according to a discrete series of multiple intensities of a predetermined basic value of said power.

13. Motor, according to claim 10, characterised in that it comprises axial connectors (33) for electronic ends (23a,23b), shaped in such a way as to be housed in a condition of geometric shape coupling with openings (41) shaped to match them of the flanged covers (17).

14. Motor, according to claim 1, characterised in that said shaft (4) is hollow.

15. Motor, according to claim 1, characterised in that said shaft (4) is provided with front coupling means (34) for connecting to a further shaft (4) in such a way that they axially continue on from each other.

16. Motor, according to claim 15, characterised in that said coupling means (34) comprise teeth (35a) and compartments (35b), axially shaped to match each other, which can penetrate each other head on and longitudinally to the axis (11) of said shafts (4).

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