NZ314673A - Electric motor wheel accommodates disc brake elements - Google Patents

Description

91 New Zealand No. 314673 International No. PCT/ TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: 14.07.1992; Complete Specification Filed: 08.07.1993 Classification: (6) B0OK7/OO; H02K7/14 Publication date: 24 June 1997 Journal No.: 1417 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Electric motor wheel Name, address and nationality of appiicant(s) as in international application form: HYDRO-QUEBEC, a body corporate organised under the laws of Canada of 75 West, Rene-Levesque Boulevard, Montreal, Quebec H2Z 1A4, Canada 314673 Under the provisions of Regu* J«tion 23 p) th» - Co^rUie SfWCrfVr} ts.\is 1 ■■ r*..

Patents Form No. 5 Our Ref: JT207978 This is a divisional out of application No. 254035 dated 6 July 1993.

NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION ELECTRIC MOTOR WHEEL We, HYDRO-QUEBEC, a body corporate organised under the laws of Canada of 75 West, Rene-Levesque Boulevard, Montreal, Quebec H2Z 1A4, Canada, hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: ^r^vTnf i (followed by page 1 a) PT0523120 -1a- ELECTRIC MOTOR-WHEEL This invention relates to an electric motor-wheel.

PRIOR ART: In U.S. Patent No. 4,223,255 ofGaiy S. GOLDMAN, issued on 16 September 1980, a motor-wheel is described having a controller and a double function circuit without brushes suitable for commutation or rectifying, contained entirely within the wheel. This motor-wheel is designed for use principally in an electric vehicle with four motor-driven wheels. This motor-wheel is supplied by batteries via a power conversion circuit located outside the motor-wheel.

With this type of motor-wheel, if a motor with relatively high torque is required to be achieved, the supply leads between the power conversion circuit and the motor-wheel must be of sufficiently large diameter to be able to withstand high currents. Energy losses proportional to the length of the supply leads will be produced in such a case.

In U.S. Patent No. 1,997,974 of W. C. MOORE et al., issued on 16 April 1935, a vehicle motor-wheel is described having a flange forming an inner surface of the wheel, and an internal brake compartment, located inside a central portion cf the flange. However, it is to be noted, amongst other matters, that the central shaft of the motor is set off towards the outside which exposes the motor to external impacts.

In U.S. Patent No. 4,913,258 of Hiroshi SAKURAI et al., issued on 3 April 1990, a motor-wheel is described which has an external rotor, comprising an articulation, a hub engaged coaxially with the articulation, a wheel disc rotatably affixed to the periphery of the hub, a wheel affixed to the periphery of the wheel disc, a rotor mounted on an external side of the wheel disc, and a stator mounted coaxially in relation to the rotor and separated from the latter by a small air-gap, and mounted on the hub. One of the drawbacks with this motor-wheel having an external rotor, lies in the feet that a strong current must be fed into the supply wiring which supplies the winding of the core of the armature to achieve a powerful motor-wheel having high torque, even if the speed is nil. With this type of motor-wheel with external rotor, a converter must be provided. This converter is mounted on the inside of the - « vehicle and may prove to be very cumbersome. Such high currents circulating in the supply AMENDED PAGE (followed by page 1 b) 314673 * -1b- 3f4.. wires produce heat representing an energy loss. Furthermore, the supply wires may^profte be somewhat heavy.

In U.S. Patent No. 754,802 of Ferdinand PORSCHE et al., issued on 15 March 1904, an arrangement is described which comprises an axle, a wheel, the hollow bearing of the wheel, the end of the spindle which extends into the bearing, and a central connector between the shaft and the bearing which has its axial projection arranged at right angles to the plane 10 of the wheel. Here again, to achieve a powerful motor-wheel, the current supplied to the brushes, which comes from the outside of the motor-wheel, must be a high current. This high current must be led by means of cables or conductors of large diameter to reduce energy losses.

In U.S. Patent No. 2,348,053 of J.E. BOWKER, issued on 2 May 1944, improvements are described to a vehicle provided with electric motors consisting of a plurality of wheels mounted so as to be capable of being driven, a dynamo-motor forming an integral part of each wheel, and electrical circuit connections located between banks of switches, dynamo-motors and accumulators to control the operation of the dynamo-motors operating as motors according to the position of a selector-switch. Here again, the armature windings AMENDED PAGE {followed by page 2) will need to be supplied with a high current in order to achieve a powerful motor, such high currents necessitating large-diameter cables to conduct the energy from the vehicle's accumulators to the armature windings. Such large-diameter cables or leads are rigid and cumbersome.

The following U.S. Patents describe various motor-wheels: 638,643; 643,854; 2,506,146; 2,514,460; 2,581,551; 2,608,598; 3,566,165; 3,704,759; 3,792,742; 3,812,928; 3,892,300; 3,897,843 ; 4,021,690; 4,346,777; 4,389,586; 1,709,255; 2,335,398; and 3,548,965.

None of the above-mentioned Patents show the means required to reduce the diameter of the supply cables between the motor-wheel and the supply source when a powerful motor-wheel is required to be constructed.

One of the aims of this invention is to propose an electric motor-wheel wherein a variable alternating current is led into the windings of the stator of the motor-wheel, and wherein the wires or cables of relatively small diameter may be utilised to supply electrical energy to the motor-wheel even in the case where a powerful motor-wheel is required.

Furthermore, one of the aims of this invention is to propose a motor-wheel the weight of which is reduced whilst at the same time remaining compatible with standard braking systems.

One of the other aims of this invention, achieved by means of a preferred embodiment of this invention, is to propose a motor-wheel having a Rl/R2 ratio which is as close as possible to 1, where R, is the distance between the air-gap of the motor-wheel and the axis of rotation of said motor-wheel, and R2 is the distance between the surface of the rim affixed to the motor-wheel, which is adapted to receive a tyre, and the axis of rotation of said motor-wheel.

Furthermore, one of the aims of this invention is to propose a motor-wheel which gives out less heat and thus produces less energy-loss.

Furthermore, one of the aims of this invention, achieved by means of preferred embodiments, is to propose a motor-wheel which is equipped with means for cooling said motor-wheel when it is in operation.

Furthermore, one of the aims of this invention, achieved by means of preferred embodiments of the latter, is to propose a motor-wheel which is detachable from a suspension arm.

ABSTRACT OF THE INVENTION It is an object of this invention to provide an improved motor-wheel or to at leasV provide the public with a useful choice.

The invention relates to an electric motor-wheel comprising: - a hollow shaft with a first opening at a first end thereof, and a second opening at a second end thereof, wherein said first opening being capable of receiving conductors from outside the motor-wheel; - a stator coaxial with and affixed to said shaft, said stator comprising a central portion affixed to said shaft, a support extending radially from said central portion, a circular peripheral pole piece, said pole piece being affixed to the peripheral ends of said support; - a rotor coaxial with said stator and mounted such as to enable it to rotate about said stator, said rotor comprising a housing having a cylindrical casing having an inner surface equipped with a magnetic means surrounding said stator and separated therefrom by an air-gap, said housing comprising an inner casing mounted on one side of said cylindrical casing, and an outer casing mounted on the other side cf said cylindrical casing, said shaft extending across a central portion of said inner casing, said inner casing of the housing extending inside the width of said cylindrical casing in such a way that said inner casing defines a circular and concentric space in relation to said first end of the shaft, such a space having dimensions predetermined, thus enabling part at least of the braking system to be mounted inside that space.

The aims, advantages and other characteristics of this invention will be further clarified by reading the following, non-limiting, description of preferred embodiments, by making reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS 4 314673 Figure 1 is an partial sectional side view of an embodiment of this electric motor-wheel, in conjunction with a rim, a tyre and an articulated connecting-rod; Figure 2 is a partial section front view of the rotor and stator of the electric motor-wheel shown in Figure 1, including the details of construction of the central portion; Figure 3 is an enlarged view of a part of Figure 1; * Figure 4 is a sectional view across line 4-4 of Figure 3; Figure 5 is a front view of a part of the electric motor-wheel shown in Figure 1; Figure 6 is an enlarged view of a part of Figure 1; Figure 7 is a sectional view along line 7 - 7 of Figure 5; Figure 8 is a front view of the rim with the tyre shown in Figure 1; Figure 9 is a sectional view along line 9-9 of Figure 8; Figure 10 is an enlarged view of a part of Figure 9; Figure 11 is an enlarged view of a part of Figure 9; Figure 12 is an enlarged view of a part of Figure 1; Figure 13 is a rear view of the elements shown in Figure 12; Figure 14 is a rear view of the articulated connecting-rod shown in Figure 1, partially in section. — Figure 15 is a rear view of an element of Figure 1 on which the articulated cconnecting-rod is joined; Figure 16 is a view from below partially in section of the rear portion of the electric motor-wheel shown in Figure 1; Figure 17 is a rear view of the articulated connecting-rod in combination with a disc brake; Figure 18 is a schematic block diagram of an electric conversion system in accordance with the present invention; Figure 19 is a partial sectional side view of another embodiment of the electric motor-wheel according to the invention; Figure 20 is a partial sectional side view of another embodiment of the motor-wheel according to this invention; Figure 21 is a schematic block diagram of another embodiment of the electric conversion system according to this invention; Figure 22 is a partial side view of another embodiment of the electric motor-wheel according to the invention; 314*73 Figure 23 is a partial sectional front view of the stator and rotor of the electric motor-wheel shown in Figure 22; Figure 24 is another partial sectional side view of the embodiment of the electric motor-wheel shown in Figure 1; and Figure 25 is an enlarged view of a part of Figure 1.

DETAILED DESCRIPTION OF THE DRAWINGS In the various figures of the drawings, the corresponding elements are identified by the same numerical indices.

If Figures 1 and 2 are referred to now, there are shown respectively, a partial sectional side view of one embodiment of the electric motor-wheel, in conjunction with a rim 28, a tyre 32 and an articulated connecting-rod 50; and a partial sectional front view of the rotor 10 and stator 6 of the electric motor-wheel shown in Figure 1. The electric motor-wheel comprises a hollow shaft 2 with a first opening at one end, and a second opening . The first opening receives conductors 4 from outside the motor-wheel. The stator 6 is coaxial with and attached to the shaft 2, said stator 6 being provided with hollow portions 11 and windings 8.

In Figure 2, some sections only are indicated by no. 8, but it should be understood that there are windings completely surrounding the stator 6. The stator 6 is attached to the shaft 2 but it may be removed from the latter when the motor-wheel is not in operation.

The rotor 10 is coaxial with the stator 6 and is rotatably mounted about the stator 6. The stator 6 includes openings forming the hollow portions 11 between the arms 13 to reduce its weight. The motor-wheel is also equipped with a conversion system for converting an electric input current into a variable alternating electric current. The conversion system 12 comprises a microprocessor unit 44, a direct current/alternating current converter including power electronics 14 mounted within the hollow portions 11, input terminals 15 for receiving the input electric current led by means of conductors 4 and output terminals 16 for generating the variable electric alternating current. It should be understood that the conversion system may be reversible, in such a way that the electric motor may be used as a generator. The frequency of the electric variable alternating current is representative of the required speed of rotation of the rotor 10, the phase angle of the variable alternating electric current determines whether the motor-wheel functions as a motor or as a generator, and the amplitude of the variable alternating electric current is representative of the torque required.

The user of this motor-wheel may utilise conductors of relatively small diameter to lead electrical power inside the motor-wheel if such power is produced based on a high voltage as the power electronics 14 is on the inside the motor-wheel. Such power electronics 14 will convert the high voltage and low current input stream into a high current stream to supply the winding 8 of the stator as a variable alternating current. Having regard to the fact that the power electronics 14 is already on the inside of the motor-wheel, conductors of large diameter needed to lead the electric current of the conversion system 12 to the winding 8 of the stator will be relatively short. Of course, the power electronics 14 includes condensers, transistors, diodes and other components of the kind known to a person having skill in the art.

To reduce the weight or the diameter of the electric conductors, a high supply voltage may be utilised in accordance with the following relationship: P = IV, where P is the power, I is the current and V is the voltage. IV increases, then I is reduced. At low speed, the power is low, the latter implying that the current supplying the converter is equally low since the voltage is constant. But, if high torque is required, the current supplying the winding of the stator must also be high. The arrangement of the power electronics of the converter inside the'housing enables the electric supply conductors to be chosen to suit the desired motor power whilst making high torque possible at low speed. Furthermore, the converter enables the impedance of the motor to be suited to that of the supply source at high voltage.

The stator 6 comprises a central portion attached to the shaft 2, arms 13 extending radially from the central portion, and a circular and peripheral pole piece including metal laminates 27 on which the winding 8 is wound. The pole piece is affixed to the peripheral ends of the arms 13.

The rotor 10 comprises a housing having a cylindrical casing 17 the inside surface of which is equipped with a magnetic means 26 surrounding the stator and separated from it by an air-gap. Having regard to the fact that the air-gap is relatively small, it can not be seen on figures 1 and 2, but its location is indicated on Figure 25 by means of R,. The housing comprises an inner casing 18 arranged on one side of the cylindrical casing 17, and another casing 20 arranged on the other side of the cylindrical casing 17. The shaft 2 extends across a central portion of the inner casing 18.

The casing forming part of the rotor 10 fits over the shaft 2 in a sealed manner, the stator 6 and the conversion system 12. A sealed joint 23 is provided. The motor-wheel includes a first ball-bearing 22 joined to the inner casing 18, and a second ball-bearing 24 joined to the outer casing 20. The ball-bearings 22 and 24 are mounted, respectively at two different parts of the shaft 2 such that the rotor 10 can rotate about the stator 6 by means of ball-bearings 22 and 24. A threaded bolt 23 is provided to affix the stator 6 in relation to the shaft 2. A stop-ring 21 is also provided. A compression ring 127 is provided to affix the ballbearing 22.

The stator 6 requires at least two arms located between the openings to support the pole piece of the stator 6. Also, the support may comprise three equally spaced arms, extending radially to the peripheral ends of the stator 6. In Figure 2, it can be seen that the stator 6 includes four equally spaced arms 13. In the embodiment shown in Figures 1 and 2, the magnetic means of rotor 6 comprises a series of permanent magnets 26. In Figure 2, some only of the magnets are identified by number 26, but it should be understood that these magnets 26 are provided all around the stator 6. The stator 6 is made in part out of a light weight material capable of conducting heat. Preferably, this material is an aluminium alloy. The motor-wheel comprises in addition, a rim 28 affixed around an outer surface of the housing, and a band 30 made from an elastomer and fitted between the rim 28 and the housing. The rim 28 is made suitable to receive the tyre 32. The rim 28 is flat-based. The magnets 26 are preferably made from neodymium, iron and boron. The band 30 prevents penetration of water or dust between the housing and the rim 28 to prevent the wheels from becoming out of balance.

The peripheral ends of the arms 13 are affixed to the pole piece of stator 6 by means of a circular member 34 which forms an integral part of the peripheral ends of the arms 13. The circular member 34 has its outer surface provided with notches 36. The pole piece of stator 6 has an inner surface provided with projecting tongues 37 of matching shape to mesh with the notches 36 to affix the pole piece of stator 6 to the circular member 34. The circular member 34 has in inner surface provided with projecting portions 38, such that efficient heat exchanging can be achieved by means of the projecting portions 38 when air circulation is produced inside the housing. Some projecting portions only are indicated by number 38 so as not to encumber Figure 2. The support of stator 6 and the circular member 34 are made from an aluminium alloy whilst the pole piece of stator 6 is made from steel.

It is to be noted that the ends of the cross formed by the arms 13 of stator 6 are - 4 aligned with the notches 36 for mechanical reasons. Thus, the projecting portions 38 which are distributed around the circular member 34 are, in relation to their longitudinal dimension, 8 3146 out-of-phase in relation to the shaft of the motor-wheel, along the circumferential direction of the member 34 so as to mechanically reinforce it.

If Figures 1, 2 and 25 are referred to now, the air-gap is positioned at a predetermined distance Rl from the central axis 3 of shaft 2. The rim 28 has a surface 29 to receive the tyre 32 which is positioned at a pre-determined distance R2 from the central axis 3 of shaft 2. R/Rs should be substantially within the range between 0.65 and 0.91 to achieve an efficient motor-wheel. The higher the ratio R/Rj, the better is the efficiency of the motor-wheel. But, as there are physical limitations, the motor-wheel shown in Figures 1, 2 and 25 has a Rj/F-i rat'° °f substantially 0.91.

For a motor with a radial air-gap, the torque T is proportional to L . Rj2 . IB, where L is the width of the pole, R, is the radius of the air-gap and IB is the current of the winding. For the design of this motor-wheel, the width L of the pole piece has been maximised. By having several poles, the weight of the pole piece of the magnetic circuit may be reduced so as in so doing to reduce the weight of the rotor and the moment of inertia of the rotor, thus allowing for the presence of a cavity for the inclusion of a braking means. The present motor-wheel augments torque T by having a wide pole piece and by having a high R,/R2 ratio where the theoretical limit which is unattainable, is 1. This motor-wheel also supplies high power because P =T. co which is proportional to L . R2 .1. to, where o> is the angular frequency of the rotor. This motor-wheel includes a rotor in the form of a cross to reduce the weight of the motor-wheel, to allow for the cooling of the winding, and to allow for a space in the hollow portions 11 which will provide room to mount the conversion system. The stator in the form of a cross supports the conversion systt.ii and is utilised as a cooling element.

The motor-wheel preferably has thirty two poles. This motor-wheel can function with sixteen poles but it is preferable to have a large number of poles to reduce the weight of the motor-wheel. The conductors 4 are preferably constructed as coaxial cable including fibre optics. This coaxial cable prevents the emission of radiation.

In the description which is to follow, the same reference numbers relate to similar elements throughout the set of drawings.

If Figures 1, 2 and 18 are referred to now, the conversion system comprises a direct current/variable alternating current converter where input circuit 40 receives a direct current from input terminals 15, and three output circuits 42 to generate three phase-alternating currents in the output terminals 16. The alternating currents need not necessarily be three phase currents, polyphase currents may also be utilised. The conversion system also includes 31A*?3 a microprocessor unit 44 connected to arms 41a, 41b, 41c of the converter to control its operation. The microprocessor unit may be located outside the motor-wheel. The conversion system shown in Figure 18 may be utilised when the rotor has not been supplied with < n electric current. As may be seen from Figure 2, the stator 6 is in the form of a pross an.! Ka? four arms 13. The converter comprises three arms 41a, 41b, and 41c which gene, a c, respectively, the three phase-alternating currents, the arms 41a, 41b and 41c being af>>:ed, respectively, to three of the arms four arms 13 of the stator 6. These three arms 41a, 411- and 41c form part of the power electronics 14 shown in Figure 2.

The power electronics shown in Figure 2 includes thf, arms 41a, 41 o, 41c of the converter shown in Figure 18 output also include the condenser 43 shown .n Figure 18. In this Figure 18, only one condenser is shown to simplify this Figure 18, but in the embodiment shown in Figure 2, the condenser 43 is distributed over three condensers arranged, respectively, on three of the four arms 13 shown in Figure 2. It is not essential for the control amplifiers 91 to be inside the housing. Each of the arms 41a, 41b, 41c of the converter include one commutation section and one control section which is formed by the control amplifiers 91. The microprocessor unit 44 is affixed to the fourth of the arms 13. It is to be noted that the microprocessor unit 44 may also be mounted outside the motor-wheel, as it does not generate a high current. The motor-wheel includes in addition, two circular distribution and supply buses 48 connected to the arms 41a, 41b 41c of the converter and to the microprocessor unit 44, such that the direct current carried by the conductors may be distributed to the arms 41a, 41b, 41c of the converter, and to the microprocessor unit 44 by means of bus 48. Please note that the converter may be a direct current/alternating current converter where a high voltage alternating current is carried by the conductors.

If Figures 1, 12, 13, 14 and 15 are referred to now it may be seen that the shaft 2 is equipped with a means of connection at its first end whereby the motor-wheel may be connected to a support member. This support member is an articulated connecting-rod 50.

This means of attachment is constructed from an annular member 52 whose outer edge is equipped with slots 54 at regular intervals, alternating with projecting portions 56 such that the annular member 52 may mesh and lock with a complementary part of the articulated connecting-rod 50.

The projecting parts of the outer edge have widths varying in the circumferential direction. The complementary part of the articulated connecting-rod 50 also has an annular section 58 having a diameter sufficient for the annular section 58 to be slipped over the outer 314673 edge of the shaft 2. The annular section 58 has slots 60 and projecting parts 62 of complementary shape which are made suitable to mesh with the projecting parts 56 and the corresponding slots 54 of the outer edge of the annular member 52. The projecting parts of the annular section 58 have widths varying in the circumferential direction such that the annular section 58 can slip over the outer edge and turn in relation to said outer edge to mesh in its assembled position. Similarly, a spanner 66 is provided, having splines 68 which may be inserted into cavities 55 which are produced when the annular section 58 is turned in relation to the external edge of the shaft 2 to lock the shaft 2 in relation to the articulated connecting-rod 50. Holes 63 are provided to affix a disc brake (shown on Figures 16 and 17).

The articulated connecting-rod 50 is equipped with an elongated inner groove 70 whose first end is adjacent to the annular section 58 and a second end at a distance from said annular section 58, such that the conductors 4 may be led to the shaft 2 along said elongated groove 70. The spanner 66 has an elongated section 72 equipped with an elongated inner cavity, the elongated section 72 being suited to mesh with the inner groove 70 of the connecting-rod 50 along part of its length to protect the conductors 4. The part of the groove 70 which is not protected by the elongated section 72, is equipped with an element of protection (not shown) to cover the conductors 4. It is to be noted that the lower edge of the splines 68 is slightly skewed so as to facilitate the insertion and locking of the splines 68 into the cavities 55. The holes 65 are provided to affix the spanner 66 on to the shaft 2. The threaded holes 67 are provided to facilitate the withdrawal of the spanner 66.

Referring now more specifically to Figure 15, the first end of the shaft has an inner part equipped with a cavity 74 having ground edges 76 taking the shape of square corners such that said cavity may receive a spanner (not shown on the Figures) to turn the shaft 2.

Referring now more specifically to Figures 1, 18 and 25, a measuring means to measure the speed of rotation and the position of the rotor 10 in relation to the stator 6 is provided, this means comprising a fibre optic cable 80 the first end of which being connected to the microprocessor unit 44, and the second end positioned such that it is adjacent to the rotor 10. The measuring means also includes a circular light reflector 82 mounted on the rotor 10 in such a way that when said rotor 10 is turning, the reflector passes in front of the second end of the fibre optic cable 80, such that the speed of rotation and the position of the rotor 10 in relation to the stator 6 may be calculated by means of the microprocessor unit 44. It is to be noted that the circular reflector 82 is made up of a series of reflectors having different characteristics of refection, such that the position of the rotor 10 in relation to the stator 6 11 314673 may be determined at all times. The fibre optic cable SO consists of at least one fibre.

Referring now more specifically to Figure 18, the fibre optic cable 80 and the reflector 82 form an encoder which is connected to a decoder of position 83 of the microprocessor unit 44. The decoder of position 83 comprises an optical make-and-break, a light source, a photo-detector and other electronic components. The microprocessor unit 44 also includes a controller 85 having an input circuit 87 to detect currents in the winding 8 of the stator and an output circuit 89 to disconnect the arms 41a, 41b, 41c of the converter by means of the control amplifiers 91. The microprocessor unit 44 is similarly equipped with a communication interface 93 to link with another intelligent device. It is not ncuev?.;y for the control amplifiers 91 to be inside the housing.

Referring to figures 1,16 and 17, it may be seen that the ianer casing 18 of the housing has an outer surface of concave shape to produce, when t ie rotor 10 is turning, air circulation towards the periphery of the inner casing 18. The outer surface is equipped with a series of elongated parallel blades 90 extending towards the shafr 2. Ths blades have their ends free forming a space 92 in which a part of the braking means "• \ may be mounted, thus efficient heat exchange may be achieved across the inner casing 18 and the braking means 94 may be cooled by the circulation of air produced along the inner casing 18.

Referring now more specifically to Figures 16 and 17, it may be seen that the braking means 94 is a disc brake having a disc 96 bolted on to the inner casing 13. As known in the art, this braking disc includes an attaching lug suitable to mesh with the disc 96. Shown diagrammatically, the knuckled articulation joint 100 and the steering &nn 102 of the steering system may be seen. Each of the blades 90 is equipped with threaded cavities 104 used to mount a drum brake in place of a disc brake 94. Bolts 95 are provided to affix the disc brake to the inner casing 18.

Attachments 106 may be seen, to affix the disc brake 94 tc rhr; connecting-rod 50. Also visible, are the bolts 108 to support the attaching lug, and pistons 110 suited to mesh with pads 99. From Figures 1,16 and 17 it may be seen that the knuckled articulation joint of the steering system is quite close to the shaft 2 in such a way that the angle alpha (a) between the axis of rotation of the motor-wheel and the axis determined by the connecting-rod 50 and the articulation joint is advantageous. It is to be noted that the geometry of the inner casing 18 allows this advantageous position of the knuckled articulation joint 100 in ** 4 relation to the motor-wheel.

Referring now to Figures 1, 5, 6 and 7, the outer casing of the housing includes 12 31 4 f 7 3 convex and concave sections 112 and 114 which alternate along its circumferential direction, in such a way that, when the rotor is turning, air circulation is produced inside the housing by means of convex section 112 as indicated by the arrows 116, and air circulation is produced along the outer parts of the concave section 114 as indicated by the arrows 118, thus efficient heat exchange may be achieved across the outer casing. It is to be noted that Figure 6 is a partial sectional side view of Figure 5. Openings with plugs 113 are provided to allow access to the inside of the housing. Bolts 115 are provided to affix the rim 28.

Referring now to Figures 1, 3 and 4, the motor-wheel also includes a drying means, including an air tube 120 one end of which is located inside the housing, a chamber 122 located at the outer end of the tut/e 120 and a desiccant material (not shown) located on the inside of chamber 122, such that when the rotor 10 is turning, air circulation is produced inside the tube 120 and across chamber 122 to dry the air inside the housing. The chamber 122 is annular, elongated, and located inside the hollow shaft 2. The chamber 122 is open at each of its ends. The opening of the shaft which is adjacent to the articulated connecting-rod 150 is sealed. It may be seen from Figure 1 that one end of the tube 120 is adjacent to the peripheral part of the stator 6, the tut*3 120 is mounted between the outer casing 20 and the stator 6 to the point where it reaches the opening of the shaft 2, then it is brought along chamber 122 such that its other end 124 may be located at one end of the chamber as shown in Figures 3 and 4. The end 124 of the tube 120 is passed through the airtight end of the hollow shaft and the chamber 122 in such a way that the air passing through tube 120 has to go across the chamber where it is dried.

The conductors 4 have a fibre optic cable 126 at their central part, a first electrical conductor 128 and a second electrical conductor 130 separated from the first conductor by an insulating material 132. The conductors 4 are protected by an outer sheath 134.h Referring now to Figures 8, 9, 10 and 11, it may be seen that a tyre 32 is affixed to the rim 28 in a permanent manner when the motor-wheel is assembled. The motor-wheel is equipped with a rim with a flat base 28, with a first side flange 142 which may be welded to the rim 28, and a second side flange 144, whirh is affixed to the rim 28 by means of bolts 146 and with an L-shaped member 148 welded to the rim 28. The relationship between the rim 28, one of the bolts 146 and the L-shaped member 148 may be seen more readily in Figure 10. The tyre 32 may be inflated by means of a valve 150 allowing access to the inside of the tyre 32. This valve 150 may be seen in a more detailed manner in Figure 11.

Having regard to the fact that the rim 28 is flat-based, the tyre 32 can not be lifted 31467J 13 from the rim 28. With such a motor-wheel, when the tyre is worn, the rim 28 and the tyre have to be replaced.

Referring now to Figure 19, a motor-wheel similar to that depicted in Figure 1 may be seen, in which the drying means is different. This drying means comprises ah air tube 120 having one end located inside the housing, and a chamber 121 equipped with an inflatable balloon set into a housing 127, located at the other end 12S of the tube 120. A desiccant material is placed inside the chamber 121, thus, when the temperature or the atmospheric pressure change, air circulation is produced inside tube 120 and across the chamber 121 to dry the inside of the casing. As may be seen, the chamber 121 is located on the outside of the motor-wheel. The opening of the shaft 2 which is adjacent to the articulated connecting-rod 50 is airtight. The tube 120 is used as exit from as well as entry to the chamber 121.

Referring now to Figure 20, an electric motor-wheel may be seen wherein the rotor comprises a magnetic means including a pole piece constructed from metal laminates on which a winding 9 is wound, the stator is equipped with brushes 111 which are connected to an output circuit of the conversion system 12. The rotor is equipped with a conducting contact surface,located such that it can engage the brushes 111. The contact surface is connected to the winding 9 of the rotor 10.

Referring now more specifically to Figures 20 and 21, the conversion system 12 includes a direct current/alternating current converter having four arms 41a, 41b, 41c and 4Id, an input circuit to receive a direct current from input terminals 40 and four output circuits 45 and 43 to generate a direct current for the winding 9 of rotor 10 and three phase-alternating currents for the windings 8 of stator 6. The conversion system also includes a microprocessor unit 44 connected to the arms 41a, 4lb, 41c and 41d, to control its operation. The winding 9 and the laminations of the rotor 10 on which the winding 9 is wound may be replaced by a conducting ring.

Referring now to Figures 22 and 23, a motor-wheel is shown comprising an induction rotor. The rotor comprises a magnetic means including a pole piece constructed from metal laminates on which the winding 9 is wound, thus an electric current may be induced in the winding 9 of the rotor by means of an electromagnetic field produced by the electric current fed into the windings 8 of the stator 6.

The reference number 8 in Figure 23, represents all the windings which are distributed around the stator even if only a part of the windings is shown. Similarly, the reference number 9, in Figure 23, represents the winding which is arranged ail around the rotor. The conversion u ■1 14 system 12 includes a direct current/alternating current converter having three arms 41a, 41b, 41c, an input circuit to receive a direct current from input terminals 15 which are connected to the bus 48 and three output circuits which generate three phase-alternating currents in the output terminals 16. Also, the conversion system 12 includes a microprocessor unit 44 5 connected to the converter to control its operation.

* As may be seen from Figure 23, the stator is in the form of a cross having four arms 13. The converter includes power electronics which is constructed in part from three arms of the converter which generate, respectively, the three phase-alternating currents. The rrms of the converter are affixed, respectively, to three of the four arms 13. The motor-wheel 10 includes, in addition, two circular supply and distribution buses connected to the power electronics 14 and to the microprocessor unit 44.

The air-gap is positioned at a pre-determined distance Rl from the central axis 3 of the shaft 2. The rim 28 has a surface for receiving the tyre 32 which is positioned at a predetermined distance R2 from the central axis 3 of the shaft 2. The ratio R,/!^ is of the 15 order of 0.65 to 0.80 when the rotor is equipped with a winding. The higher the ratio is, the better is the efficiency of the motor-wheel. In the embodiment shown in Figures 22 and 23, the ratio is of the order of 0.80.

Referring now to Figure 24, it may be seen that the stator 6 is cylindrical, and equipped with longitudinal and parallel slots 200 to receive the windings of the stator 6. In 20 order to avoid encumbering Figure 24, some only, of the slots have been identified by the number 200. The slots are skewed in relation to the longitudinal axis 3 of the shaft 2 in such a way that each of the slots 200 has its lower end substantially aligned with the upper end of the adjacent slot in order to produce steady torque when the motor-wheel is in operation.

Whilst this invention has been described above by way of preferred embodiments, such 25 preferred embodiments may, of course, be modified at will, whilst still remaining within the field defined by the attached claims v/ithout changing or altering the nature or scope cf this invention.

A 314673

Claims (6)

WHAT WE CLAIM IS:

1 • Electric motor-wheel comprising: 10 - a hollow shaft with a first opening at a first end thereof, and a second opening at a second end thereof, wherein said first opening being capable of receiving conductors from outside the motor-wheel; - a stator coaxial with and affixed to said shaft, said stator comprising a central portion affixed to said shaft, a support extending radially from said central portion, a circular 15 peripheral pole piece, said pole piece being affixed to the peripheral ends of said support; - a rotor coaxial with said stator and mounted such as to enable it to rotate about said stator, said rotor comprising a housing having a cylindrical casing having an inner surface equipped with a magnetic means surrounding said stator and separated therefrom by an air-gap, said housing comprising an inner casing mounted on one side of said cylindrical casing, 20 and an outer casing mounted on the other side of said cylindrical casing, said shaft extending across a central portion of said inner casing, said inner casing of the housing extending inside the width of said cylindrical casing in such a way that said inner casing defines a circular and concentric space in relation to said first end of the shaft, such a space having dimensions predetermined, thus enabling part at least of the braking system to be mounted inside that 25 space.

2. Motor-wheel in accordance with claim 1 , wherein said inner casing has an outer surface of concave shape to produce, when the rotor is turning, air circulation directed around the periphery of the inner casing, such outer surface being supplied with a series of elongated, 30 parallel blades extending along the direction of the shaft, such blades having free ends defining said space in which said braking means may be mounted, thus, in operation, efficient heat exchange is achieved across the inner casing and such a braking means is cooled by air circulation produced along the inner casing. 314 ? 73

3- Motor-wheel in accordance with claim 1 or 2, wherein the end concerned of the hollow shaft which is equipped with the first opening includes a connection means to connect the shaft to one end of an articulated connecting-rod, such end of the connecting-rod being supplied with a knuckled articulation joint; and wherein the inner casing of the housing has an annular embossment facing inwards and the hollow shaft has a length shorter that the width of the cylindrical casing of the housing in such a way that said knuckled articulation joint is located close to a radial symmetrical plane of the motor-wheel when said articulated connecting-rod is connected to the shaft.

4. Motor-wheel in accordance with claim 1, wherein said housing encloses the shaft and stator in a sealed manner.

5. Motor-wheel in accordance with claim 1, .including a first ball-bearing connected to the inner casing, and a second ball-bearing connected to the outer casing, such ballbearings being mounted, respectively, on each side of the shaft in such a way that the rotor may turn in relation to the stator by means of the ball-bearings concerned.

6. Motor-wheel in accordance with claim 1, wherein said support comprises at least two arms located between the openings of said support to reduce its weight. 7 •. Motor-wheel in accordance with claim 6, wherein said sapport comprises at least three equally-spaced arms extending radially to the ends of said support. 8. Motor-wheel in accordance with claim 7, wherein said equally spaced arms comprise four equally spaced arms. 9. Motor-wheel in accordance with claim i, wherein the stator comprises a light material capable of conducting heat. 10. Motor-wheel in accordance with claim 9, wherein said material is an aluminium alloy. 11 • Motor-wheel in accordance with claim 1, including in addition a rim affixed i7 3 f 4 6 around an outer surface of said housing, and a band made from an elastomer material, mounted between said rim and housing, such rim being made suitable to receive a tyre. 12. Motor-wheel in accordance with claim 11,wherein said rim is flat. 5 13. Motor-wheel in accordance with claim 1, wherein the outer casing of the housing includes convex and concave sections extending alternately along a circumferential direction of said outer casing, in such a way that, when the rotor is turning, air circulation is produced inside said housing by means of the convex sections, and air circulation is produced along the 10 outer portions of said concave sections, thus enabling an efficient exchange of heat across that outer casing. 14. Motor-wheel in accordance with claim 1, wherein said shaft is equipped with a means of attachment of its first end, whereby the motor-wheel may be connected to a support 15 member. 15. Motor-wheel in accordance with claim 12, wherein the air-gap described is located at a predetermined distance R, from the central axis of the shaft, the rim described has a surface to receive a tyre, which is located at a predetermined distance R2 from the central axis 20 of the shaft, and R,/R2 is substantially of the order of 0.65 to 0.91. 16. Motor-wheel in accordance with claim 15, wherein the rotor is supplied with a winding, and wherein R,/R2 is of the order of 0.65 to 0.80. 17. a motor wheel substantially as herein described with reference to the accompanying drawings. END OF CLAIMS ir7 PAl PNT OFFICE ! 24 m 1997 hydro-QUebec By tne# Atttrnteys PALQW1N. affi & CA^fY