CIRCULAR STATOR FOR ELECTRIC BICYCLE

Abstract

The invention relates to a method for manufacturing a stator (8) of a two-phase or three-phase motor of an electrically assisted bicycle, comprising: - the formation of a stack of stator core laminations in a longitudinal direction of the laminations, - the formation of means for indexing the phases of the rotor; - a step of forming windings (82) on the teeth of the segments of the stack of laminations; - a step of folding the stack of laminations perpendicular to the longitudinal direction (XX), and of connecting the longitudinal ends of the laminations, thus forming a regular circular stator core; - a step of shrink-fitting the rotor (8) in a casing (3). figure for the abstract: figure 1A

Description

Title of the invention: CIRCULAR STATOR FOR AN ELECTRICALLY ASSISTED BICYCLE

[0001] TECHNICAL FIELD OF THE INVENTION AND STATE OF THE ART

[0002] The invention relates to an electric motor stator for a bicycle with electric assistance and a method of manufacturing such an electric motor stator.

[0003] We know of electric motors for electrically assisted bicycles, but their design is not optimized.

[0004] A unitary tooth stator structure is also known which allows the use of unitary tooth winding technology. The teeth are cut and assembled, which implies having a staple in the center of the tooth. This structure is therefore not optimized for the performance of the ferromagnetic material; in fact, when a staple is placed in the center of the tooth, the sheet at the location of the staple is deformed and therefore loses its magnetic properties; however, the same quantity of magnetic flux must pass through this tooth, so the magnetic flux avoids the area of ​​the staple and is concentrated around it, which locally increases the magnetic saturation of the sheet and therefore creates additional iron losses.

[0005] This structure allows for little material waste during cutting. This tooth is then overmolded and then wound, resulting in an interesting copper filling which can be slightly superior to the interpolation process. All the wound teeth are then equipped with their connectors and then assembled together, which multiplies the number of residual air gaps. In addition, the individual teeth require an interconnector to connect the coils together.

[0006] It is understood that a method for producing such a structure multiplies the assembly steps and that the performance of the structure obtained is limited, both due to its assembly steps and its geometry.

[0007] We are looking for a structure and a production method which limits the number of assembly steps and which also limits the loss of performance linked to assembly and to this geometry.

[0008] A new stator and electric motor structure for an electrically assisted bicycle is also sought. Statement of the invention

[0009] The present invention aims to remedy all or part of the drawbacks of the state of the art cited above.

[0010] In this regard, the invention firstly relates to a method of manufacturing a stator of a two-phase or three-phase motor of an electrically assisted bicycle, comprising:

[0011] - forming a stack of stator core laminations in one direction longitudinal (XX) of the sheets, the stack comprising segments connected to each other by folding zones, an outer surface of each segment being in the shape of an arc of a circle, a tooth projecting from an inner surface of each segment;

[0012] - the formation of means for indexing the phases of the motor or means identification of a unique position of the stator relative to these phases;

[0013] - a step of forming windings on the teeth of the segments of the stack of sheets;

[0014] - a step of folding the stack of sheets perpendicular to the direction longitudinal (XX), and connecting the longitudinal ends of the sheets, for example by laser welding, thus forming a regular circular stator core;

[0015] - a step of shrink-fitting the stator into a casing.

[0016] The invention therefore implements a flat, comb-shaped stator structure to produce a winding.

[0017] According to particular aspects:

[0018] - such a method may include a step of forming means, for example at least less a groove, for locking the stator in the casing;

[0019] - and / or the step of forming indexing means comprising the formation, on the around the stator, at least 3 indexing notches or grooves with 2 different intervals between them;

[0020] - and / or the outer surface of the sheets has a roughness better than 5 / 100 mm;

[0021] - and / or the stator comprises between 6 and 12 teeth, each carrying, after winding, a electric coil;

[0022] - and / or the winding is carried out by interpolation, which makes it possible to wind the structure flat stator (comb);

[0023] - and / or the winding is carried out with a wire which fills notches between teeth neighbors with a fill rate greater than or equal to 35% and for example less than or equal to 40%.

[0024] The invention also relates to a method for manufacturing a two-phase or three-phase motor for an electrically assisted bicycle, comprising:

[0025] - a step of forming a stator according to the invention;

[0026] - a step of introducing a rotor into the stator;

[0027] - a step of positioning an electronic card above the stator and the rotor;

[0028] - a step of closing the casing.

[0029] The invention also relates to a stator with a circular outer surface of a two-phase or three-phase motor of an electrically assisted bicycle, comprising:

[0030] - a circular outer surface (Cl), comprising means for indexing the phases of the motor or means for identifying a unique position of the stator relative to these phases; and an inner surface carrying teeth on which coils are wound;

[0031] - a casing in which the stator is shrunk.

[0032] According to particular aspects:

[0033] - a stator according to the invention comprises means, for example at least one groove of the stator locking in the casing;

[0034] - and / or the indexing means comprise, on the periphery of the stator, at least 3 indexing notches or grooves with 2 different intervals between them;

[0035] - and / or the outer surface of the stator has a roughness better than 5 / 100 mm.

[0036] - and / or the stator has between 6 and 12 teeth, each carrying an electric coil;

[0037] - and / or the stator comprises a core, teeth which extend from the core and onto in which a winding is made and polar expansions at the end of the teeth opposite the core; preferably, the winding is made with a wire which fills notches between the teeth with a filling rate of at least 35%, for example less than or equal to 40%.

[0038] The invention also relates to a two-phase or three-phase motor for an electrically assisted bicycle, comprising:

[0039] - a stator according to the invention;

[0040] - a rotor in the stator;

[0041] - an electronic card between, on the one hand, the stator and the rotor and, on the other hand, a housing closing cover.

[0042] Such a motor may comprise an axis of rotation and a plurality of alternating north and south magnets buried in the mass of the rotor and each having a V shape, the branches of the "V" being open towards the outside of the rotor.

[0043] The invention also relates to an electrically assisted bicycle, comprising a motor according to the invention. BRIEF DESCRIPTION OF THE FIGURES

[0044] Other advantages, aims and particular characteristics of the present invention will emerge from the following non-limiting description of at least one particular embodiment of the devices and methods which are the subject of the present invention, with reference to the appended drawings, in which: - Figures 1A and 1B are schematic representations of a stator structure according to one embodiment of the invention ([Fig.1A]) and of a motor according to one embodiment of the invention ([Fig.1B]), in a housing of a casing; - [Fig.2] is a schematic front view of an example of a stator according to the invention; - [Fig.3] is a view of a sheet metal to form a stack of an example stator according to the invention; - [Fig.4A], [Fig.4B] and [Fig.4C] represent steps in the production of a production of a stator of the invention; - [Fig.5] is a schematic view of an example rotor for an example of motor according to the invention; - [Fig. 6A] is a sectional view, perpendicular to its axis, of an example of a rotor for an example of a motor according to the invention; - [Fig. 6B] is a sectional view of a volume which makes it possible to accommodate a magnet of a rotor for an example of a motor according to the invention. - figures 7A and 7B represent a rotor mounted in an example of a stator according to the invention; - [Fig.8] illustrates an electrically assisted bicycle to which a motor according to the invention can be applied; - [Fig.9] is a schematic view of a connector that can be implemented within the framework of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] The present description is given as a non-limiting example of embodiment. In particular, it often refers to a three-phase motor, but also applies to a two-phase motor.

[0046] Figures 1A and 1B show a stator 8 according to the invention for an electric motor 2 of an electrically assisted bicycle.

[0047] This stator 8 is housed in a casing 3 of a housing and has in its center a volume 11 for receiving a rotor 6. The electric motor 2 comprises the rotor 6 and the stator 8.

[0048] The rotor is not shown in [Fig.lA], but it is shown in Figures 1B, 5-6B and in Figures 7A and 7B. In the latter, as in [Fig.lB], it is in association with the stator 8 (but without the housing 3 in Figures 7A and 7B).

[0049] As illustrated in [Fig.2], but also in [Fig.7A], this stator is provided, for example at its periphery, with means 9 i, 92, 93 for indexing the phases of the motor; these are for example slots or notches or grooves made on the peripheral surface of the stator 8, each being capable of receiving a pin or a key or, more generally, means of a shape complementary to that of the means 9i, 92, 93. The latter are arranged so that the stator can be mounted in only one position in the casing, so that the ends of the coils wound in the stator correspond to the contacts for the different phases of the motor. These contacts can themselves be located directly on the control and command means 7 described below; for example, the 3 phase wires of the winding corresponding to phases U, V, W are equipped with male connectors, the corresponding female part being directly welded onto these means 7.

[0050] For example, as illustrated in [Fig.2], two of the slots or notches 9b 92 form between them a 1st angle, for example 90°, and one 92 of these slots or notches forms, with the 3rd (93), a 2nd angle, different from the 1st angle, for example 150°. The means of the casing, of a shape complementary to that of the means 9i, 92, 93, are arranged in the same way. Thus, a single arrangement of the stator in the casing can be obtained, which guarantees exact positioning of the winding relative to the contacts of the different phases.

[0051] The casing comprises the housing 3 and a cover 5 ([Fig.lB]). It is preferably made of a material that is a good conductor of heat, for example an aluminum-magnesium alloy, to be able to evacuate the heat from the stator. It houses the electric motor 2, comprising the stator 8, the rotor 6 and the control and command system 7.

[0052] The control and command system 7 comprises, for example, an electronic card for controlling and commanding the electric motor. This electronic card comprises, for example, at least one sensor and / or a microcontroller; it forms a control and command module for the electric motor. It is in particular configured to control the position of the shaft (not shown) of the motor and the operation of the electric motor 2, in particular its torque and / or its speed.

[0053] The stator is shrunk into the casing.

[0054] For example:

[0055] - the casing is heated and the stator is pressed into the casing;

[0056] - or the stator is cooled and shrunk into the casing;

[0057] - or the casing is heated and the stator is cooled separately, then the shrinking is carried out.

[0058] Arrow 13 of [Fig.1A] represents the direction in which the stator is introduced into the housing 3 during shrink fitting. For this purpose, the outer surface C1 of the stator preferably has a very smooth surface condition, with a roughness for example of the order of 5 / 100th mm or less, for example 3 / 100th mm or 2 / 100th mm.

[0059] The stator may further comprise one or more grooves 17, 17' (see [Fig.3]) parallel to the axis ZZ' in which one or more teeth (not shown in the figures) formed in the interior volume of the housing 3 fit together to block any possible rotation of the stator in the housing 3 around the axis ZZ'.

[0060] With reference to figures 1A, 2 - 4C and 7A, 7B, the stator 8 comprises a stator core 10, an insulating portion 20, coils 82 (visible in particular in [Fig.7B]) and a rotor housing orifice 11. The stator 8 is substantially symmetrical relative to a central axis Z-Z'.

[0061] With respect to this axis Z-Z', it is delimited:

[0062] - towards the outside: by an external contour Cl,

[0063] - inwards: by an interior contour C2,

[0064] C1 and C2 each having a circular shape in each section plane of the stator 8 transverse to the axis Z-Z'.

[0065] [Fig. 3] shows an example of a sheet metal, for example made of steel, which can be stamped to form the stator. Such sheets are stacked, as shown in [Fig. 4A], in the direction of the central axis Z-Z', forming a comb structure. Then coils are formed on teeth 14 ([Fig. 4C]); the assembly is then folded around the axis Z-Z', in particular around folding incipients which are formed by notches 18 parallel to Z-Z'. The folding step results in a stator in the shape of a circle or disc centered on the axis Z-Z' (Figures 2, 7A, 7B).

[0066] The longitudinal ends 10a, 10b of the core 10 of the stator are rigidly secured to each other, for example by being fixed to each other by gluing and / or by welding.

[0067] The electric motor 2 may comprise a number of phases which is a multiple of two and / or three; it is therefore possible to have a two-phase or three-phase motor. In the embodiment shown, the number of teeth is equal to the number of coils 82 and three times the number of phases. More precisely, the electric motor 2 is here three-phase, it comprises 12 coils 82 for the three phases.

[0068] In the embodiment shown, the core 10 of the stator comprises bottom plates 12 (see [Fig.3] on a sheet), teeth 14, pole shoes 15 at the distal ends of the teeth 14, and folding notches 18. In the embodiment shown, this core 10 comprises segments or arcs of a circle 16 which each correspond to a portion of the circle formed by the outer contour C1 of the stator 8 when the latter is closed. This outer contour C1 is intended to be inserted by shrink fitting into the casing.

[0069] Each circular arc 16 comprises a base plate 12 and is provided with a tooth 14 extending from the base plate 12. In the embodiment shown, the circular arcs 16 are each delimited in their longitudinal direction XX' by the notches 18. The different segments 16 have a substantially identical structure, with the possible exception of the end segments of the stack of sheets and those provided with the orientation means 9 i, 92, 93 (slots or grooves or notches in this example).

[0070] The bottom plates 12 are of substantially constant thickness (measured along the axis ZZ'). In a plane transverse to ZZ', their central part is curved. The length of each bottom plate 12 is equal to the circumference of the outer contour Cl of the stator divided by the number of circular arcs 16. The bottom plates 12 each have an outer face SI and an inner face S3, which are substantially smooth.

[0071] The external faces SI of the bottom plates form the external faces of the stator core 10, delimiting the external contour Cl of the stator core 10.

[0072] In the embodiment shown, the bottom plates 12 comprise two beveled longitudinal ends which jointly form between them the folding notches 18 of the stator core 10, which form folding initiations for folding the stack of laminations of the stator core 10. More generally, these folding initiations generally take the form of grooves or recesses in the stack of laminations. They each extend longitudinally in directions parallel to each other and to the central axis Z-Z' of the stator.

[0073] Each tooth 14 of a segment 16 extends from the inner face S3 of the bottom plate 12 of the segment, perpendicular to the latter. The tooth 14 extends longitudinally from a first proximal end which connects it to the bottom plate 12 to a distal end which forms a pole expansion 15. The teeth therefore extend towards the inside of the stator 8 and towards the rotor 6 from the stator core 10. The teeth 14 serve as a winding support for the coils 82, when they are coated with insulating portions 20 ([Fig.7B]).

[0074] The pole shoe 15 has a general shape of an arc of a circle in cross-section of the stator 8 relative to the central axis Z-Z'. It delimits an inner surface S2 with the insulating portion 20 which partially covers it. The inner contour C2 of the stator is formed by all of the inner surfaces S2. This inner contour C2 is circular and may be discontinuous due to the separations between the inner surfaces S2; alternatively, it is substantially continuous, which improves the centering of the rotor 6 relative to the stator 8. It is centered on the central axis Z-Z' of the stator 8 and is intended to be opposite the rotor 6, being located around the magnets 62, 64 thereof and the motor shaft. It delimits the orifice 11 ([Fig.lA]) for housing the rotor 6 of the electric motor 4.

[0075] The coils 82 are located around the teeth 14 covered with the insulating portion 20. They are formed by winding a conductive wire, for example a copper wire. They are powered sequentially to rotate the rotor 6.

[0076] Figures 4A-4C illustrate steps in producing a stator according to the invention.

[0077] According to one embodiment of the invention, a stator made of a comb is used. ([Fig.4A]), obtained by stacking sheets of the type illustrated in [Fig.3].

[0078] As illustrated in [Fig.4B], the teeth of this stator are then overmolded with a thin layer 20 of plastic material, for example by a plastic injection process. This forms an electrical insulation layer. According to one embodiment, this layer insulating material 20 only partially covers the stator core, while completely covering the teeth 14 by surrounding the pole shoes 15. It can participate in delimiting the interior surfaces S2 of the segments 16.

[0079] Then ([Fig.4C]) this overmolded stator is wound by winding copper wires to form a winding 82. This is for example an interpolation winding process, which makes it possible to maximize the quantity of copper in the notches (the notches constitute the empty part between two teeth of the stator; they are intended to be filled with copper wire) of the motor, which drastically increases the performance of the latter. Interpolation winding makes it possible to wind a flat stator structure (comb-shaped): a winding needle arrives vertically on the stator whose teeth are oriented upwards; then this needle, through which the copper wire passes, turns around the teeth to wind copper turns.

[0080] For example, the three phases of the motor can be wound with 3 copper wires (one per phase), or the three phases can be wound with a single wire (without cutting it). Wires can be passed along the insulating plastic 20 to connect the coils to each other.

[0081] The wire(s) can then be inserted into phase connectors which will allow the motor to be connected to the control means 7. An example of a connector 27 is shown schematically in [Fig.9]. The stripped end 29 of a wire is inserted, the connector terminal is closed over this end, and the vertical part 31 of the connector can be connected to the means 7, for example an electronic card. The phases of the motor are thus connected to the means 7.

[0082] This overmolded, wound and connected structure can then be folded between each tooth along the fold initiation points 18, to form the circular stator.

[0083] To complete the mechanical adjustment and consolidate the stator, a weld, for example by laser, is carried out between the free ends 10a, 10b of the comb, which completes the wound stator.

[0084] The invention makes it possible to have a copper filling coefficient in the notch (or the space between 2 consecutive teeth) much higher than the technology conventionally used in electrically assisted bicycle motors: in fact, with a needle winding of known type, a filling rate of approximately 25% is achieved, compared to 35%, and even up to 40%, for the interpolation winding according to the invention. This filling rate is defined as follows: : it is the copper section in a notch (as defined above), more precisely the number N of turns x the diameter <e>uncoated copper wire) reported to the surface S of the notch without plastic insulation on the sheet metal pack (therefore NxO / S). In other words, it is the bare copper surface on bare iron of the notch.

[0085] The invention also makes it possible to optimize the proportion of material used in the assembly of the sheet metal packs: in fact, having a comb-shaped stator makes it possible to optimize the use of the sheet metal during its cutting process (round or two-part stators (star or crown) have more material waste than comb-shaped stators.

[0086] The invention makes it possible to obtain better performance than a two-part stator because there is only one residual air gap for 12 teeth (which will also be filled by a weld between the ends of the comb) compared to 12 residual air gaps for 12 teeth in the case of a two-part stator.

[0087] In the case of a 12-tooth stator, the invention makes it possible to limit deformation during bending: in fact, the bending angle is then 30° maximum, which creates almost no magnetostriction and therefore no loss of performance.

[0088] This choice of 12 teeth also makes it possible to obtain a tooth width large enough to allow the stator to be industrialized. Indeed, the sheets can be fixed together at points, called fixing points, by an interlocking process (each sheet having a punching which is inserted into the sheet below it) or by stapling. However, a minimum width of 3 mm is usually retained instead of these fixing points. The invention makes it possible to produce a larger structure, with less impact on this minimum width constraint. The invention also makes it possible to have these fixing points of the sheets on the outer yoke 12 ([Fig.3]) which has less impact on performance.

[0089] It can be noted that a structure according to the invention is not more voluminous than known structures because the copper filling coefficient can be maximized. The total volume of the motor would be increased if a winding method which has a lower filling coefficient were used to have the same performance,

[0090] Once the stator is folded and welded (see [Fig.7A]), the opening of the space 19 between neighboring pole shoes 15 is also reduced, which makes it possible to reduce the torque ripple of the motor. For a needle winding, we seek to ensure that this space is large enough (in the unfolded state of the stator, as illustrated in figures 4A-4C) to allow the needle to pass through. However, the larger this space is (in the folded state of the stator, as in [Fig.7A]), the more the torque of the motor will ripple strongly.We therefore seek to sufficiently reduce this space to reduce the torque ripple, but still have sufficient space to avoid leaks between the stator teeth (in the case where the inter-tooth space is small, then we are close to the case where there is a metallic junction between these two teeth, so there is little torque ripple but inter-tooth magnetic leaks; in the case where there is an air space between two teeth, then there is torque ripple but little inter-tooth magnetic leaks).

[0091] As already explained above, the interpolation method uses a flat (comb) stator, so this space is very large and very suitable for winding. After bending the stator, this space is reduced and the size of the pole flare 15 can be adjusted from the start to optimize this inter-tooth space. This is possible, while maximizing the copper filling during winding, thanks to the flat stator technique.

[0092] The motor 2 comprising the stator 8 has a limited footprint, while having high performance and while being relatively easy to manufacture. The improvement of the winding of the stator 8 is obtained by increasing the quantity of conductive wire which is wound around teeth 14 of the stator 8. The improvement of the winding of the stator 8 also results from the greater ease of winding around the teeth 14 of the stator 8 according to the invention in a limited winding space around the teeth 14 of stator 8.

[0093] Winding is facilitated and the amount of wound conductive wire of the stator 8 is increased due to winding the conductive wire near the smooth and flat inner face of the circular arcs compared to winding near a curved inner face of a circular stator core 10 of known structure.

[0094] By facilitating the winding of the stator 8, the manufacture of the stator 8 is facilitated. The winding is notably facilitated by winding the conductive wire around the teeth 14 of a straight stator core blank 10, before folding the stack of sheets of the stator core 10 to close it.

[0095] An example of rotor 6 which can be implemented with a stator according to the invention is described in connection with figures 5-7B.

[0096] According to one aspect of the invention, the magnets 62, 64 of the rotor are arranged in a V shape and are buried in the volume of the rotor.

[0097] The opening of each “V” is turned towards the outer surface 60 of the rotor and the inner faces of the V, turned towards the outside, delimit a volume called “tooth” 62', 64', see [Fig.6A]. As shown in [Fig.6A], each “V” comprises 2 magnets of the same polarity (one for each branch of the “V”). The magnets of every other “V” have their polarity oriented towards the corresponding ferromagnetic tooth 64', the other magnets (magnets of every other “V”) have their polarity oriented in a direction opposite to the corresponding ferromagnetic tooth 62'.

[0098] This V shape, the angle a (shown in figures 6A and 6B) of the V as well as the arrangement of the magnets make it possible to significantly increase the performance of the motor and to have a solid mechanical structure when it rotates.

[0099] The angle a is preferably between 130° or 150° and 180° (being strictly less than 180°, for example 175°) which allows magnetization after assembly, which would not be easier with an angle a less than 130° or 150°.

[0100] The rotor is obtained by a stack of sheets forming the rotor sheet pack.

[0101] According to one aspect of the invention, shown in [Fig.6B], each sheet of the stack may comprise recesses. It is thus possible to form, in the stack of the rotor sheet pack, cavities or volumes 110 to receive 2 magnets, preferably not yet magnetized (therefore not yet having their magnetic property) and means for positioning the magnets and / or means for possibly fixing the magnets by gluing or welding. The magnets are for example made of NdFeB (Neodymium, Iron and Boron, Nd2 Fei4B). Each cavity or volume may comprise 2 sub-cavities or volumes 111, 112, symmetrical with respect to a plane AA' ([Fig.6B]) which passes through the axis of rotation of the rotor.

[0102] The means for positioning the magnets and / or the means for possibly fixing the magnets by gluing or welding comprise for example:

[0103] - one or more stops 120, 120' against which the magnets can be positioned to ensure balancing of the magnetic field in the rotor;

[0104] - and / or one or more bonding zones 140, 140', for example in the form of clearances, allowing excess glue to be recovered to limit overflow into the rotor;

[0105] - and / or one or more zones 160, 160' for example one or more fairly large surfaces, to fix one or more magnets by laser welding.

[0106] Preferably, a rotor according to the invention comprises a number of groups of north 62 and south 64 magnets between 5 and 7, a number which is optimal for a rotor diameter between, for example, 35 mm and 50 mm, a diameter range suitable for electrically assisted bicycles. A smaller diameter would be insufficient (and would lead to insufficient power) and a larger diameter would be incompatible with integration into an electrically assisted bicycle.

[0107] In addition, each pair of magnets is covered with a metallic thickness, the thickness e of which is for example at least approximately 0.7 mm or between 0.5 mm and 1 mm and, at most for example between 1.5 mm and 3 mm.

[0108] Figures 7A and 7B show an example of a rotor 6 in a stator 8 according to the invention. This rotor comprises an alternation of north 62 and south 64 magnets which interact with the stator to form the electric motor.

[0109] An example of an electric bicycle to which the invention applies is shown in [Fig.8]. It comprises a frame 16 (composed of several assembled tubes), a front wheel 34, a rear wheel 36, a handlebar 38 connected to the front wheel by a fork 13, a saddle 15.

[0110] A pedal set comprises two pedals 22, 24, connected by cranks 22', 24' to an axle which enters a housing. The action of the cyclist on the pedal set drives a chain 28. In the case of an electrically assisted bicycle, an electric motor (for example according to the invention and as described above) is housed in a casing 21 which is crossed by the housing which houses the crankset axle. The casing 21 may also contain a control system 40 (in broken lines in [Fig.8]), which makes it possible to control the assistance provided to the cyclist by the electric motor. Reference 32 designates an electric battery.

[0111] The force Fl applied by a cyclist to the pedal 22 results in corresponding forces F2 and F'2 applied to the casing 20. The force F2 applied to the front part of the casing is greater than that (F'2) which is applied, in the opposite direction, to the rear part.< / e>

Claims

Claims

1. A method of manufacturing a stator (8) of a two-phase or three-phase motor of an electrically assisted bicycle, comprising: - forming a stack of stator core laminations (10) in a longitudinal direction (XX) of the laminations, the stack comprising segments (16) connected to each other by folding zones, an outer surface (13) of each segment being in the shape of an arc of a circle, a tooth (14) projecting from an inner surface (S3) of each segment; - forming means for indexing the phases of the motor; - a step of forming windings (82) on the teeth of the segments of the stack of laminations; - a step of folding the stack of laminations perpendicular to the longitudinal direction (XX), and connecting the longitudinal ends (10a, 10b) of the laminations, thus forming a regular circular stator core (10); - a step of shrinking the stator (8) into a casing (3, 5).

2. Manufacturing method according to the preceding claim, further comprising a step of forming means (17, 17') for locking the stator in the casing, comprising at least one groove in which one or more teeth, formed in the interior volume of a housing (3) of the casing, fit.

3. Manufacturing method according to one of the preceding claims, the step of forming indexing means comprising the formation, on the periphery of the stator, of at least 3 indexing notches or grooves with 2 different intervals between them.

4. Manufacturing method according to one of the preceding claims, the outer surface of the sheets having a roughness better than 5 / 100 mm.

5. Manufacturing method according to one of the preceding claims, the stator comprising between 6 and 12 teeth, each carrying an electric coil.

6. Manufacturing method according to one of the preceding claims, the winding being carried out by interpolation.

7. Method according to one of claims 1 to 6, in which the winding is carried out with a wire which fills notches between neighboring teeth with a filling rate greater than or equal to 35%.

8. Method for manufacturing a two-phase or three-phase motor of an electrically assisted bicycle, comprising: - a step of forming a stator (8) according to one of the preceding claims; - a step of introducing a rotor (6) into the stator; - a step of positioning an electronic card (7) for controlling the stator and the rotor; - a step of closing the casing.

9. Stator (8) with a circular outer surface of a two-phase or three-phase motor of an electrically assisted bicycle, comprising: - a circular outer surface (Cl), comprising means (9i, 92, 93) for indexing the phases of the motor and an inner surface carrying teeth (14) on which coils (82) are wound; - a casing (3, 5) in which the stator is shrunk.

10. Stator according to the preceding claim, comprising means (17, 17'), for example at least one groove, for locking the stator in the casing.

11. Stator according to one of claims 9 or 10, the indexing means (9i, 92, 93) comprising, on the periphery of the stator, at least 3 indexing notches or grooves with 2 different intervals between them.

12. Stator according to one of claims 9 to 11, the outer surface of the stator having a roughness better than 5 / 100 mm.

13. Stator according to one of claims 9 to 12, the stator comprising between 6 and 12 teeth, each carrying an electric coil.

14. Stator according to one of claims 9 to 13, the stator comprising a core (10), teeth (14) which extend from the core and on which a winding (82) is produced and pole shoes (15).

15. Stator according to claim 14, wherein the winding is made with a wire which fills notches between the teeth with a filling rate of at least 35%.

16. Two-phase or three-phase motor for an electrically assisted bicycle, comprising: - a stator according to one of claims 9 to 15; - a rotor in the stator; - an electronic card (7) between, on the one hand, the stator and the rotor and, on the other hand, a cover (5) for closing the casing.

17. Motor according to claim 16, the rotor (1) comprising an axis (ZZ') of rotation and a plurality of alternating north and south magnets (2, 4) buried in the mass of the rotor and each having a V shape, the branches of the "V" being open towards the outside of the rotor.

18. An electrically assisted bicycle, comprising a motor according to claim 16 or 17.

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