Electric motor, electric motor stator, and related manufacturing method

Abstract

To provide an electric motor having high torque and small weight.SOLUTION: An electric motor includes a plurality of teeth (17) each having a first connector and a second connector, a plurality of coils (9) which are formed so as to be wound around the respective teeth and are formed such that first ends of winding wires are disposed in the respective first connectors while second ends of the winding wires are disposed in the respective second connectors, and center modules (7) which are formed so as to receive the respective teeth, and include a connection frame provided with connection tabs extending in a radial direction and formed to be inserted into the first connectors or second connectors of the respective teeth. The connection frame is formed to offer electrical connection between the coils.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of electric motors, and more particularly to an electric motor intended to be attached to an electric bicycle.

Background Art

[0002] Electric bicycles are becoming increasingly popular because they consume less energy, have less impact on the environment, are low-cost, and are easy to move.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, the use of electric motors in electric bicycles involves several constraints. In particular, it is necessary to provide high torque and low rotational speed to perform effective assistance and at the same time adapt to the speed at which the cyclist pedals.

[0004] Furthermore, in order to be able to install the electric motor without impairing other features of the bicycle, when the electric motor is generally arranged on the bicycle, in the region of the bottom bracket assembly of the bicycle, it faces size constraints. Also, it is necessary to suppress the noise generated by the electric motor.

Means for Solving the Problems

[0005] Therefore, in order to at least partially address these constraints, the present invention seeks to provide a compact electric motor capable of generating a relatively high torque.

[0006] Therefore, one subject of the present invention is, a plurality of separate teeth provided with a first connector and a second connector, A plurality of coils configured to be wound around a plurality of separate teeth, wherein the first end of the winding wire is configured to be placed in a first connector and the second end of the winding wire is configured to be placed in a second connector, A central module configured to receive separate teeth, the central module comprising a connecting frame having connecting tabs that extend radially and are configured to be inserted into a first or second connector of the separate teeth, the connecting frame being configured to provide an electrical connection between coils, This is a stator for an electric motor, equipped with the following features.

[0007] Using a central module with a connecting frame configured to connect the stator coils, and separate teeth configured to be fixed to the central module, makes it possible to obtain a stator that is quick and easy to assemble, thus enabling large-scale mass production.

[0008] According to another aspect of the present invention, the connecting frame comprises a central ring from which connecting tabs associated with the connecting frame extend.

[0009] According to another aspect of the present invention, the central rings of the connecting frames are stacked axially and separated from each other by non-conductive intermediate walls of the central modules.

[0010] According to another aspect of the present invention, the intermediate wall is made of plastic.

[0011] According to another aspect of the present invention, the stator also comprises a field frame configured to be positioned around the separate teeth when the separate teeth are positioned on a central module.

[0012] According to another aspect of the present invention, the coils are connected in a star configuration or a delta configuration.

[0013] According to another aspect of the present invention, the connecting frame is configured to connect the coils in a full-pitch winding configuration, and the phase coils are connected in parallel to one another.

[0014] According to another aspect of the present invention, the connecting frame is configured to connect the coils in a fractional pitch winding configuration, and at least some of the phase coils are connected in series.

[0015] According to another aspect of the present invention, the central module also comprises an additional connector configured to allow power to be supplied to the coil via an external power supply.

[0016] The present invention also relates to an electric motor comprising a rotor and a stator, as described above.

[0017] According to another aspect of the present invention, the motor is a three-phase brushless motor, and the rotor has 10 or 14 poles. Different numbers of poles are also possible.

[0018] The present invention also relates to a method for manufacturing a stator, as described above, and the method comprises the following steps: The steps include winding a coil around a separate tooth, The steps include arranging the ends of the coil winding wires into separate toothed first and second connectors, The steps include connecting the coil and the connecting frame by connecting separate teeth to the central module so that the connecting tabs of the connecting frame are inserted into the first and second connectors, The steps include: positioning a field frame around separate teeth, Includes.

[0019] According to another aspect of the present invention, the winding step includes winding a winding wire onto a winding frame to form a coil, and the assembly comprising the winding frame and the winding wire forms separate teeth configured to be positioned on the stator body.

[0020] According to another aspect of the present invention, connecting the separate teeth to the central module includes clip - fastening the first connector and the second connector to the connection tab.

[0021] Further features and advantages of the present invention will become more apparent by reading the following description and the accompanying drawings, which are given by way of illustrative and non - limiting examples.

Brief Description of the Drawings

[0022] [Figure 1] It is a schematic perspective view of a part of an electric motor according to a first embodiment. [Figure 2] It is a schematic perspective view of a central module of a stator, having a connection frame intended to connect the coils of the stator. [Figure 3] It is an electrical circuit diagram of a standard star winding for a three - phase electric motor with 15 coils. [Figure 4] It is an electrical circuit diagram of a short - pitch star winding for a three - phase electric motor with 18 coils. [Figure 5] It is a perspective view of a stator with separate teeth. [Figure 6] It is an enlarged view of a part of the stator of FIG. 1. [Figure 7] It is a schematic perspective view of a part of a stator according to a modification of an embodiment. [Figure 8] It is a flowchart of the steps of a method for manufacturing a stator.

Modes for Carrying Out the Invention

[0023] In these figures, the same elements are given the same reference numerals.

[0024] The following embodiments are illustrative. While the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that features apply only to a single embodiment. Individual features from various embodiments may be combined or substituted to create other embodiments.

[0025] In this specification, several elements or parameters may be indexed, for example, a first element or a second element, a first parameter and a second parameter, or a first criterion and a second criterion. In this case, this is a simple index for distinguishing and indicating elements, parameters, or criteria that are similar but not identical. This index does not imply that one element, parameter, or criterion takes precedence over another, and such names can be easily interchanged without departing from the scope of this specification. This index also does not imply, for example, a chronological order for evaluating such criteria.

[0026] Figure 1 is a partial view of an electric motor 1 comprising a stator 3 and a rotor 5. The electric motor 1 is, for example, a brushless electric motor, but the present invention is not limited to this type of motor. Such an electric motor 1 is particularly suitable for mounting on an electric bicycle, but the present invention is not limited to this application.

[0027] The stator 3 comprises a central module 7 shown in Figure 2. The central module 7 comprises connecting frames 11 configured to connect coils 9 intended to be arranged around the central module 7. The central module 7 comprises, for example, four connecting frames 11 configured to connect the coils 9 to each other.

[0028] Figure 3 shows a first electrical configuration in which the stator 3 comprises 15 three-phase coils 9, with the phases indicated as u, v, and w, and the coils 9 are star-connected in a standard full-segment winding configuration, i.e., the various coils 9 of phases u, v, and w are arranged in parallel. Such a stator 3 can be used in a 10-pole motor 1.

[0029] Figure 4 shows a second electrical configuration in which the stator 3 comprises 18 three-phase coils 9, indicated by phases u, v, and w, and the coils 9 are in a short-segment winding configuration, i.e., several coils 9 of phases u, v, and w are connected in a series winding in a star configuration. In this particular case, each phase u, v, and w comprises two branches of three coils 9 arranged in series, and the two branches are arranged in parallel. The short-segment winding allows for a smoother transition as the poles of the rotor 5 pass through the teeth of the stator 3, and thus makes it possible to reduce the noise generated by the motor 1. Such a stator 3 can be used in a 14-pole motor.

[0030] Such a configuration makes it possible to obtain high torque while simultaneously reducing the size of the electric motor 1.

[0031] The present invention is not limited to the two winding configurations shown in Figures 3 and 4, meaning that other configurations of coils 9 having a different number of coils 9, or coils 9 connected in parallel for each phase u, v, and w, may also be used. A delta-connected stator 3 winding and a rotor 5 with a different number of poles can also be used.

[0032] In this way, the connecting frame 11 makes it possible to obtain the desired connection between the coils 9. The connecting frame 11 comprises, for example, a central ring 11a from which connecting tabs 11b associated with the connecting frame 11 extend. The central rings 11a are, for example, stacked axially and separated from each other by non-conductive intermediate walls 13 to avoid short circuits between the connecting frames 11. The connecting frame 11 is manufactured from, for example, a metal, particularly aluminum, brass, copper, or iron, and the intermediate walls 13 are manufactured from, for example, plastic.

[0033] Each connecting tab 11b may have a proximal first end with a straight, S-shaped or Z-shaped, i.e., vertically extending connecting bar that extends radially from the central ring 11a and compensates for differences in axial height between the various central rings 11a, and a distal second end configured to connect to one end of the coil 9. The connecting tabs 11b of the various connecting frames 11 may be uniformly arranged around the central ring 11a. Adjacent connecting tabs 11b are spaced apart from each other to avoid short circuits between the various connecting frames 11.

[0034] The central module 7 may also include additional connectors 15, for example, three additional connectors 15 that extend axially and are configured to allow power to be supplied to the various phases u, v, and w via an external power supply of the stator 3.

[0035] The central module 7 is configured to receive separate teeth 17 formed by a winding frame on which winding wires are wound to form a coil 9. A cylindrical field frame 19 (as seen in Figure 1) is also configured to be positioned around the separate teeth 17. The field frame 19 includes axial channels, or slots 190, configured to receive, for example, the end pieces 170 of the separate teeth 17, thereby enabling the separate teeth 17 and the field frame 19 to be fixed to each other.

[0036] The separate teeth 17 are removable from the field frame 19. Figure 5 shows an example of a stator 3 with separate teeth 17, wherein the field frame 19 has multiple slots 190 extending axially into the inside of the field frame 19. In Figure 5, the stator 3 has 18 separate teeth 17, but stators 3 with different numbers of separate teeth 17, in particular 15 teeth as in Figure 1, can of course be manufactured. The slots 190 have, for example, a dovetail or T-shaped cross section. Thus, the teeth 17 are fitted with fixed end pieces 170 having a cross section shape that complements the cross section shape of the slots 190. The fixed end pieces 170 are intended to be introduced into the slots 190 of the cylindrical component 19 by the translational motion of the fixed end pieces 170 in the slots 190. The teeth 17 are fixed in place as a result of the complementarity of the shapes of the fixed end pieces 170 and the slots 190. By using a stator 3 with separate teeth 17, it becomes possible to wind the coils 9 onto the winding frame that forms the teeth 17 before arranging the teeth 35 on the field frame 19. This reduces the space required between the coils 9 so that they can be placed at narrower intervals from one another. This also makes it possible to arrange the teeth on the central module 7.

[0037] Furthermore, the separate teeth 17 of the stator 3 are provided with a first connector 17a and a second connector 17b (as shown in Figure 6). The first connector 17a is configured to connect to a first end of the winding wire of the coil 9, and the second connector 17b is configured to connect to a second end of the winding wire of the coil 9. The ends of the winding wires can be secured to the first connector 17a and the second connector 17b by contact (for example, to the connectors 17a and 17b having housings configured to receive the winding wires, as in the case of self-stripping connectors, or to a connecting tab 11b which may have a self-stripping type end piece configured to receive the ends of the winding wires), by brazing, or by soldering. Furthermore, the first connector 17a and the second connector 17b are configured to receive the distal end of the connecting tab 11b when the separate teeth are inserted into the central module 7, so that the teeth can be secured to the central module 7. The connection may be made, for example, by clipping separate teeth 17 onto the central module 7 via the connecting tab 11b and connectors 17a, 17b. The first connector 17a and the second connector 17b each have, for example, two U-shapes that face each other and form slots configured to receive the ends of the coil 9. The distal end of the connecting tab 11b is configured to contact the ends of the winding wires held in the connectors 17a, 17b, thus achieving contact between the ends of the coil 9 and the connecting tab 11b received by the connectors 17a, 17b. In Figures 1 and 6, the slots in the connectors 17a and 17b are oriented radially, and the connecting tab 11b extends linearly to contact the ends of the coil 9 positioned in the slots. In this way, the connecting tab 11b forms a male part configured to be introduced into the complementary female part formed by the connectors 17a and 17b, so that the connecting tab 11b and the connectors 17a, 17b, which have the ends of the winding wires, are mechanically and electrically connected. Alternatively, the female part of the mechanical connection may be supported by the connecting tab 11b, and the male part by the connectors 17a and 17b.

[0038] Figure 7 shows a modified example of one embodiment in which connectors 17a and 17b each have a U-shape with a slot at its branch, and the end of the coil 9 extends tangentially between the two slots. The connecting tab 11b has a C-shaped or S-shaped distal end, and the S-shaped or C-shaped cavity of the connecting tab contacts the end of the coil 9 extending between the two slots of connectors 17a and 17b.

[0039] Any other configuration of the connectors 17a and 17b, as well as the connecting tabs that ensure contact between the end of the winding wire and the connecting frame, can be used just as well.

[0040] As shown in Figure 1, the stator 3 comprises a plurality of separate teeth 17, although a different number of separate teeth 17 may be used. The separate teeth 17 may have an H-shaped radial cross-section forming a winding frame configured to hold the windings that form the coil 9. The coil 9 is formed on each separate tooth 17 by the winding turns of the windings.

[0041] The windings forming the coil 33 generally comprise multiple turns that extend adjacent to each other between the radial ends of separate teeth 17. Furthermore, multiple layers of turns may be superimposed around the separate teeth 17.

[0042] The present invention also relates to an electric motor 1 comprising a stator 3, as previously described. The electric motor 1 also comprises a rotor 5 configured to be located inside the stator 3, i.e., facing the central module 7 and positioned in its center, such that the rotor is arranged inside separate teeth 17 comprising coils 33 (as seen in Figure 1). The electric motor 1 is, for example, a brushless three-phase DC motor and has, for example, 10 poles or 14 poles (in the case of an electric motor 1 having 15 or 18 coils 9), but other types of electric motors 1 with different numbers of poles may also be used. The poles are generated, for example, using permanent magnets arranged on the rotor 5.

[0043] The present invention also relates to a method for manufacturing a stator 3, as described above.

[0044] Figure 8 is a flowchart of the steps of a method for manufacturing such a stator 3.

[0045] The first step 101 is to wind a wire for winding a coil 9 onto a separate tooth 17. The separate tooth 17 forms a winding frame having, for example, an H-shaped cross-section and configured to hold the turns that form the coil 9. The coil 9 comprises multiple turns extending between the branches of the H. The coil 9 may comprise several layers of overlapping turns. The winding is performed, for example, by a robot, and all coils 9 may be equivalent.

[0046] The second step 102 includes positioning the first end of the winding wire of the coil 9 into the first connector 17a of separate teeth 17, and the second end of the winding wire of the coil 9 into the second connector 17b of separate teeth 17. The connectors 17a, 17b are provided with slots into which, for example, the ends of the winding wire are positioned. The ends of the winding wire may be held in the connectors 17a, 17b by mechanical retention (as in the case of a self-stripping connector), by brazing, or by welding.

[0047] The third step 103 includes positioning a central module 7, which has a connecting frame, at the center of the stator body.

[0048] The fourth step 104 includes connecting the coil 9 to the connecting frame 11 by inserting separate teeth 17 onto the central module 7 so that the connecting tab 11b of the connecting frame 11 is inserted into the first connector 17a and the second connector 17b. The connecting tab 11b is configured to contact the end of the winding wire of the coil 9 at the first connector 17a or the second connector 17b. Fixation is achieved, for example, by clipping the separate teeth 17 onto the central module 7.

[0049] The fifth step 105 includes positioning a field frame 19 around a separate tooth 17. The field frame 19 is positioned on the separate tooth 17 by axial translation such that a slot 190 in the field frame receives a fixed end piece 170 of the separate tooth.

[0050] Thus, by using a central module 7 equipped with a connecting frame 11 and separate teeth 17 positioned on the central module 7 and configured to connect the coil 9 and the connecting frame 11, it becomes possible to obtain a stator 3 that is quick and easy to assemble. Furthermore, by creating axially stacked connecting frames and using separate teeth, it becomes possible to reduce the radial size of the stator 3.

Claims

1. A stator (3) for an electric motor (1), comprising: a plurality of separate teeth (17) provided with a first connector (17a) and a second connector (17b); a plurality of coils (9) configured to be wound around the plurality of separate teeth (17), wherein a first end of a wire of the winding is configured to be disposed in the first connector (17a), and a second end of the wire of the winding is configured to be disposed in the second connector (17b); a central module (7) configured to receive the separate teeth (17), the central module (7) comprising a connection frame (11) extending in a radial direction and having a connection tab (11b) configured to be inserted into a first connector (17a) or a second connector (17b) of a separate tooth (17), the connection frame (11) being configured to provide an electrical connection between the coils (9); a stator (3) comprising the above.

2. The stator (3) according to claim 1, wherein the connection frame (11) comprises a central ring (11a) from which the connection tab (11b) associated with the connection frame (11) extends.

3. The stator (3) according to claim 2, wherein the central rings (11a) of the connection frame (11) are axially stacked and separated from each other by a non-conductive intermediate wall (13) of the central module (7).

4. The stator (3) according to claim 1, further comprising a field frame (19) configured to be disposed around the separate teeth (17) when the separate teeth (17) are disposed on the central module (7).

5. The stator (3) according to claim 1, wherein the connection frame (11) is configured to connect the coils (9) in a full-pitch winding configuration, and the coils of the phases (u, v, w) are connected in parallel with each other.

6. The stator (3) according to claim 1, wherein the connection frame (11) is configured to connect the coils (9) in a short-pitch winding configuration, and at least some of the coils (9) of the phases (u, v, w) are connected in series.

7. An electric motor (1) comprising a rotor (5) and a stator (3) according to any one of claims 1 to 6.

8. A method for manufacturing a stator (3) according to any one of claims 1 to 6, the step of winding the coil (9) around the separate tooth (17); the step of disposing the ends of the winding wire of the coil (9) on the first connector (17a) and the second connector (17b) of the separate tooth (17); the step of connecting the separate tooth (17) to the central module (7) such that the connection tab (11b) of the connection frame (11) is inserted into the first connector (17a) and the second connector (17b), thereby connecting the coil (9) and the connection frame (11); the step of disposing the field magnet frame (19) around the separate tooth (17); A manufacturing method comprising the above steps.

9. The winding step includes winding a winding wire around a winding frame to form a coil (9), and an assembly including the winding frame and the winding wire is configured to form a separate tooth (17) disposed on the stator body (31). The manufacturing method according to claim 8.

10. The step of connecting the separate tooth (17) to the central module (7) includes clip-fastening the first connector (17a) and the second connector (17b) to the connection tab (11b). The manufacturing method according to claim 8.

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