WO2010079375A1

WO2010079375A1 - Device for producing torque, in particular an orientation device

Info

Publication number: WO2010079375A1
Application number: PCT/IB2009/000010
Authority: WO
Inventors: Jean-Marie Van Appelghem; Vincent Bourquin; André Wacinski
Original assignee: Numexia Sa
Priority date: 2009-01-07
Filing date: 2009-01-07
Publication date: 2010-07-15
Also published as: EP2380260A1; CN102362414A

Abstract

The present invention relates to a device for producing torque, in particular an orientation device, including an electric motor (15, 16), a speed reducer (6, 16, 23-27, 29, 36), and a rotational output member (35) coupled to the speed reducer, the speed reducer including a rotational input member (16) rotating at the rotational speed of the motor and means (23-27, 29, 36) engaging with the rotational input member (16) so as to rotate the rotational output member (35) at a speed less than the rotational speed of the motor. The invention is characterized in that the electric motor includes a stator (15) and a rotor (16) surrounding the stator (15), and in that the rotor (16) constitutes the rotational input member of the speed reducer.

Description

Device for producing torque, in particular an orientation device

The present invention relates to a torque generating device, more particularly to a device comprising an electric motor and a speed reducer.

It is known that electric motors run at speeds that are often much higher than the required input speeds of the mechanisms they control. To remedy this problem, speed reducers are used which are interposed between the motor and the mechanism to be driven. A speed reducer thus generally comprises an input shaft which rotates at the rotational speed of the motor, an output shaft and, in between, speed reducing members which enable the output shaft to rotate. at a lower speed than the engine. In a known type of speed reducer, called cycloidal or trochoidal reducer, the input shaft has an eccentric peripheral face with which the speed reduction members cooperate. Examples of cycloidal speed reducers are described in US Pat. No. 4,194,415, US Pat. No. 4,526,064 and EP 0 291 052.

A disadvantage of speed reducers is that by interposing between the motor and the mechanism to be controlled, they increase the overall size, in particular the axial size. The present invention aims at providing a device for producing torque with reduced axial dimensions.

To this end, there is provided according to the invention a torque generating device comprising an electric motor, a speed reducer and a rotational output member coupled to the speed reducer, the speed reducer comprising a rotatable rotating input member. at the speed of rotation of the motor and means cooperating with the rotary input member for rotating the output rotary member at a speed lower than the rotational speed of the engine, characterized in that the electric motor comprises a stator and a rotor surrounding the stator and in that the rotor constitutes said rotational input member of the speed reducer.

Particular embodiments of the invention are defined in the appended dependent claims 2-7.

Other features and advantages of the present invention will appear on reading the following detailed description given with reference to the accompanying drawings in which:

- Figure 1 is an axial sectional view of a torque generating device according to a first embodiment of the invention; and

- Figure 2 is an axial sectional view of a torque generating device according to a second embodiment of the invention.

Throughout the following description, the terms "lower" and "upper" will be used with reference to the torque producing device as it appears in FIGS. 1 and 2, that is to say oriented from top to bottom. . In practice, the device according to the invention may be used in positions other than that shown.

As shown in Figure 1, a torque generating device according to a first embodiment of the invention comprises a frame 1 consisting of several parts rigidly joined to each other. The frame 1 more specifically comprises an annular support plate 2, an outer ring 3, an intermediate ring 4 held between the lower face of the support plate 2 and the upper face of the outer ring 3 by clamping screws 5 or any another suitable means of assembly, a meshing ring 6 mounted in the central bore of the annular plate 1 and bearing on the upper face of the intermediate ring 4 and an annular upper portion 7 resting on the upper face of the meshing ring 6, the assembly 4, 6, 7 being held by clamping screws 8 or any other suitable means of assembly. The parts 2, 3, 4, 6, 7 forming the frame 1 are concentric about an imaginary axis designated in FIG. 1 by reference numeral 9. A part 10 concentric with the axis 9 defines a cylindrical central part 11, or hub, extending along the axis 9 inside the frame 1, and an upper plate 12 extending in a plane transverse to the axis 9 at the upper end of the hub 11. The plate 12 is fixed at its peripheral portion 13, for example by screws (not visible in Figure 1), an upper annular face of the upper frame portion 7. The part 10, with its hub 11 and its upper plate 12 is rigidly fixed to the frame 1. The part 10 has a central axial through bore 14 allowing for example the passage of electric cables.

Around the hub 11 is fixed rigidly an electric motor stator 15. The stator 15 typically comprises, in a manner well known per se, a stack of conductive sheets interconnected by electric cables. The stator 15 is surrounded by an electric motor rotor 16, comprising a body 17 and permanent magnets 18 fixed on the cylindrical internal face 19 of the body 17, opposite the stator 15. The motor formed by the stator 15 and the rotor 16 operates as a conventional electric motor, that is to say that the supply of the stator 15 electric current causes a rotation of the rotor 16 about the axis 9 without contact between the stator 15 and the rotor 16. However, unlike traditional electric motors, the stator 15 is here located inside and the rotor 16 outside.

The stator 15 and the inner face 19 of the rotor body 17, which carries the magnets 18, are concentric with the axis 9. The outer face of the rotor body 17 comprises a cylindrical upper portion 20 and a cylindrical lower portion 21 which are concentric with the axis 9 and a cylindrical central portion 22, larger in diameter than the parts 20 and 21, which is eccentric with respect to the axis 9. The eccentricity of the middle portion 22 is low, it is inconspicuous in Figure 1. An upper ring 23 and a lower ring 24 cooperate by their inner face respectively with the upper and lower portions 21 of the outer face of the rotor body 17 by means of respective first and second bearings 25, 26. An annular gear 27 having an external toothing 28 cooperates on its inner face with the eccentric middle part 22 of the outer face of the rotor body 17 by means of a third bearing 29. The external toothing 28 of the pinion 27 meshes with an internal toothing of the 6 meshing crown but has one tooth less than this internal toothing. The outer face of the upper ring 23 cooperates with the inner face of the upper frame part 7 by means of a fourth bearing 30. An inner ring 31 concentric with the axis 9 cooperates on its outside with the inner face. the outer ring 3 via a fifth bearing 32. The bearings 25, 26, 29, 30 and 32 are for example ball or roller bearings. The inner ring 31 is fixed rigidly against the lower face of the lower ring 24. More specifically, the inner ring 31 is held by clamping screws 33 or any other suitable means of assembly between the lower face of the lower ring 24 and the upper face of an upper rim 34 of an output shaft or drive shaft 35 concentric with the axis 9. The upper and lower rings 23, 24 are fixed rigidly to one another by pins 36 which pass through bores of the pinion 27 having a greater section than the pins 36. The rotary assembly 16, 23-29, 31 is held assembled and fixed axially relative to the frame 1 in particular by shoulders provided on the outer face of the body rotor 17 and on the rings 23, 24, by the bearing 30 bearing against the plate 12 and the frame 1, by the bearing 32 and by the screws 33.

The torque producing device illustrated in FIG. 1 operates in the following manner. When the rotor 16 is rotated about the axis 9 relative to the frame 1, the rotation of the eccentric portion 22 and the meshing between the pinion 27 and the meshing ring 6 make the pinion 27 a rotational movement around the axis 9 combined with a gyration movement. The rotational movement of the pinion 27 is performed at a lower speed, and even much lower, at the speed of rotation of the rotor 16. This rotational movement is communicated to the upper and lower rings 23, 24 by the pins 36 which can move in the corresponding bores of the pinion 27. The inner ring 31 and the output shaft 35 are integral with the rings 23, 24 and therefore rotate concentrically around the axis 9, relative to the frame 1, at a speed much lower than that of the rotor 16. A high torque can thus be produced with a small engine. During its rotational movement, the rotary assembly constituted by the upper and lower rings 23, 24, the pinion 27 and the inner ring 31 is guided by the bearings 30 and 32.

In a particular application of the invention, the output shaft 35 is connected at its lower end (not shown) to a set of wheels of a vehicle, such as a handling vehicle, a bus, a plane, etc. to form a steerable wheel train by the device according to the invention. In this application, the device according to the invention not only has a function of orientation of the wheels but also a function of recovery of the forces exerted by the ground, these forces being in fact transmitted by the output shaft 35, via the crown 31, to the outer ring 3 and more generally to the frame 1. An electric motor located near the wheels and supplied by cables passing through the internal bore 14 of the hub 11, allows the wheels to rotate about their axis to make advance the vehicle. Other applications than the orientation of a wheel-train can be envisaged for the device according to the invention, for example the orientation of a crane, a turret, a communication antenna, blades of a wind turbine, the rotation of a winch, etc. Note that the output shaft 35 is not necessarily present. In some applications, in fact, a part to be rotated, other than a shaft, can be coupled directly to the inner ring 31. The concentric surface portions 20, 21 and eccentric 22, the pinion 27, the ring gear 6, the rings 23, 24, the pins 36 and the bearings 25, 26, 29 constitute a cycloidal speed reducer whose operation is , in itself, of known type. An important advantage of the invention is conferred by the fact that the concentric surface portions 20, 21 and eccentric 22, in particular the eccentric portion 22, are defined by an electric motor rotor and not by a traditional connected gear shaft. outside the gearbox to a motor. By this characteristic of the invention, in fact, the motor and the speed reducer are integrated in one and the same device, the speed reducer surrounding the rotor and the stator of the motor, and the rotor of the motor has two different functions, namely produce a rotation in cooperation with the stator and print on the speed reducer gear a combined movement of rotation and gyration. The overall axial dimension of the motor-speed reducer assembly is thus significantly reduced. The radial size is not or is slightly increased compared to a traditional speed reducer.

Although in one piece in the example illustrated in Figure 1, the body 17 of the rotor 16 could consist of several pieces rigidly joined to each other. Conversely, the frame 1 could be monoblock, in other words the support plate 2, the intermediate ring 4, the outer ring 3, the ring gear 6 and the upper frame portion 7 could form a single room. Furthermore, although the use of bearings is preferable, the invention does not exclude the use of other means allowing the rings 23, 24 and pinion 27 to rotate relative to the rotor 16 and to the inner ring 31 to rotate relative to the outer ring 3, for example sliding rings.

With reference to FIG. 2, a torque generating device according to a second embodiment of the invention comprises a frame 40 made up of parts rigidly connected to one another, namely an annular plate of support 41, an outer ring 42 and an upper ring 43 clamped between the lower face of the support plate 41 and the upper face of the outer ring 42 by nut bolts 44. Other means of assembly than the bolts to Nuts 44 could of course be used to assemble parts 41 to 43.

The parts 41 to 43 forming the frame 40 are concentric about an imaginary axis designated in FIG. 2 by the mark 45. A part 46 concentric with the axis 45 defines a central cylindrical portion 47, or hub, extending along the axis 45 inside the frame 40, and an upper plate 48 extending in a plane transverse to the axis 45, at the upper end of the hub 47. The plate 48 is fixed at its level. peripheral part, for example by means of screws 49, at a projecting portion of the upper face of the upper ring 43. The part 46, with its hub 47 and its upper plate 48, is thus rigidly connected to the frame 40. The piece 46 has a central axial through bore 50 allowing for example the passage of electric cables.

Around the hub 47 is rigidly fixed an internal stator of electric motor 51 which cooperates with an external rotor of electric motor 52. The stator 51 and the rotor 52 are identical to those described in relation to the first embodiment. In particular, the outer face of the body 53 of the rotor 52 has an upper portion 54 and a lower portion 55 concentric with the axis 45 and a central portion 56 eccentric with respect to the axis 45. The concentric upper portion 54 is separated from the inner face of the upper ring 43 by a first bearing 57. The eccentric middle portion 56 cooperates with the inner face of a pinion 58 via a second bearing 59. The pinion 58 comprises an external toothing 60 which meshes with an internal toothing of an inner ring 61 but which has one tooth less than this internal toothing. The outer face of the inner ring 61 cooperates with the inner face of the outer ring 42 by means of a third bearing 62. A lower ring 63 is fixed rigidly against the underside of the inner ring. 61, and the inner face of this lower ring 63 cooperates, via a fourth bearing 64, with the concentric lower portion 55 of the outer face of the rotor body 53.

Pins 65 are rigidly fixed in the upper ring 43 and pass through bores in the gear 58, bores which have a larger section than the pins 65. An output shaft or drive 66 concentric with the axis 45 is fixed by an upper flange 67 against the underside of the lower ring 63. The assembly of the inner ring 61, the lower ring 63 and the output shaft 66 is performed for example, as shown, by means of screws 68 which clamp the lower ring 63 between the inner ring 61 and the flange 67 of the shaft 66. A plate 69 fixed against the underside of the lower ring 63, in a central bore of the shaft 66, protects the inside of the speed reducer and center the stator 47. The movable assembly 52, 58, 61, 63 is held assembled and fixed axially relative to the frame 40 in particular by shoulders provided on the outer face of the rotor body 53 and r the rings 43, 63, by the screws 68 and by the bearing 62.

The torque producing device according to this second embodiment operates in the following manner. When the rotor 52 is rotated about the axis 45 relative to the frame 40, the rotation of the eccentric portion 56, the meshing between the pinion 58 and the inner ring 61 and the cooperation between the pinion 58 and the pins 65, which hold the pinion 58 in rotation, make the pinion 58 gyration movements. Each gyration of the pinion 58 rotates the inner ring 61 one step of its teeth, relative to the frame 40, also driving the lower ring 63 and the output shaft 66 integral with the inner ring 61. The reducer of the speed constituted by the outer face of the rotor 52, the pinion 58, the inner ring 61 and the pins 65 is a cycloidal reducer operating in a manner which, in itself, is known. As in the first embodiment, a significant advantage in terms of space is conferred by the fact that the surface parts concentric members 54, 55 and eccentric 56, in particular the eccentric portion 56, are defined by an electric motor rotor and not by a conventional gear shaft. The torque generating device according to this second embodiment has, compared to that according to the first embodiment, the advantage of being even more compact in the axial direction.

Although in one piece in the example shown in Figure 2, the body 53 of the rotor 52 could consist of several pieces rigidly joined to each other. Conversely, the frame 40 could be in one piece, in other words the support plate 41, the upper ring 43 and the outer ring 42 could form a single piece. Moreover, although the use of bearings is preferable, the invention does not exclude the use of other means allowing the rings 43, 63 and the pinion 58 to rotate relative to the rotor 52 and to the inner ring 61 to rotate relative to the outer ring 42, for example sliding rings.

Claims

A torque generating device comprising an electric motor (15, 16), a speed reducer (6, 16, 23-27, 29, 36) and a rotary output member (35) coupled to the speed reducer, the speed reducer comprising an input rotational member (16) rotating at the rotational speed of the motor and means (23-27, 29, 36) cooperating with the rotary input member (16) for rotating the rotary output member (35) at a speed lower than the rotational speed of the motor, characterized in that the electric motor comprises a stator (15) and a rotor (16) surrounding the stator (15) and that the rotor (16) constitutes said rotational input member of the speed reducer.

2. Device according to claim 1, characterized in that the rotary output member (35) is integral with an inner ring (31) mounted to rotate relatively in an outer ring (3) forming part of a frame ( 1) of the device.

3. Device according to claim 2, characterized in that the inner ring (31) cooperates with the outer ring (3) by means of a bearing (32).

4. Device according to claim 2 or 3, characterized in that the outer face of the rotor (16) comprises first and second portions (20, 21) concentric with the axis (9) of the motor and an eccentric portion (22). located between the first and second concentric parts (20, 21), in that said means comprise a pinion (27) mounted to rotate relative to the eccentric portion (22), a third ring (6) forming part of the frame ( 1), surrounding the pinion (27) and meshing with this last, first and second rings (23, 24) located on either side of the pinion (27) and mounted movably in relative rotation around the first and second concentric portions (20, 21) respectively and pins (36) binder the first and second rings (23, 24) and traversing the pinion (27) with a clearance, and in that the inner ring (31) is integral with the first and second rings (23, 24).

5. Device according to claim 2 or 3, characterized in that the outer face of the rotor (52) comprises first and second parts (54, 55) concentric with the axis (45) of the motor and an eccentric portion (56) located between the first and second concentric parts (54, 55), in that said means comprise a pinion (58) rotatably mounted relative to the eccentric portion (56), a first ring (43) forming part of the frame ( 40) and movably mounted in relative rotation about the first concentric portion (54), a second ring (63) integral with the inner ring (61) and mounted to rotate relatively relative to the second concentric portion (55), and pins (65) fixed to the first ring (43) and traversing the pinion (58) with a clearance, and in that the inner ring (61) comprises an internal toothing meshing with an external toothing (60) of the pinion (58) .

6. Device according to claim 4 or 5, characterized in that the first ring (23; 43), the second ring (24; 63) and the pinion (27; 58) cooperate with the outer face of the rotor (16; ) through respective bearings (25, 26, 29; 57, 64, 59).

7. Device according to any one of claims 1 to 6, characterized in that the speed reducer is cycloidal type.