CN115622287A

CN115622287A - Hub motor

Info

Publication number: CN115622287A
Application number: CN202211382791.XA
Authority: CN
Inventors: 郭高阳; 徐仁鹏; 殷芳国; 包治斌
Original assignee: Guangdong Dingli Motor Technology Co ltd
Current assignee: Guangdong Dingli Motor Technology Co ltd
Priority date: 2022-11-07
Filing date: 2022-11-07
Publication date: 2023-01-17

Abstract

An in-wheel motor is provided, including a stator and a patent. The stator includes a stator core and a coil assembly. The stator core includes 27 pole teeth. The coil assembly includes a first phase coil set, a second phase coil set, and a third phase coil set. The first phase coil group includes: a first phase first branch including a single first wire; a first phase second branch including a single second wire; and a first phase third branch including a single third wire. The second phase coil set includes: a second phase first branch including a single fourth wire; a second phase second branch comprising a single fifth wire; and a second phase third branch comprising a single sixth wire. The third phase coil group includes: a third phase first branch comprising a single seventh wire; a third phase second branch comprising a single eighth wire; and a third phase third branch comprising a single ninth wire. The rotor includes a rotor frame and 30 sheet-like permanent magnets arranged at intervals in a circumferential direction.

Description

Hub motor

Technical Field

The present disclosure relates to a hub motor, and more particularly to a 27 slot 30 pole hub brushless motor.

Background

A27-slot 30-pole hub brushless motor belongs to the field of electric bicycles, the voltage of a common lithium battery pack is 36V, 48V and the like, and the voltage of the battery pack cannot be too high (such as 72V). This is because the high voltage is connected in series with more cells and a stronger battery protection function module, and the battery cost increases greatly, which directly results in an increase in the vehicle purchase cost of the user. Since the battery pack voltage cannot be too high, a high efficiency in-wheel motor is required.

Disclosure of Invention

At least one embodiment of the present disclosure provides an in-wheel motor including a stator and a rotor. The stator includes a stator core and a coil assembly. The stator core includes a stator main body and 27 pole teeth extending radially outward from the stator main body, and the 27 pole teeth include first to twenty-seventh pole teeth arranged in order in a circumferential direction. The coil assembly includes a first phase coil set, a second phase coil set, and a third phase coil set. The first phase coil assembly includes: a first phase first branch including a single first wire; a first phase second branch including a single second wire; and a first phase third branch including a single third wire. The second phase coil set includes: a second phase first branch including a single fourth wire; a second phase second branch comprising a single fifth wire; and a second phase third branch comprising a single sixth wire. The third phase coil assembly includes: a third phase first branch comprising a single seventh wire; a third phase second branch comprising a single eighth wire; and a third branch of a third phase including a single ninth wire, the first wire being wound from the thread end to the thread end in turn around the first pole tooth in the first winding direction, around the second pole tooth in a second winding direction opposite to the first winding direction, and around the third pole tooth in the first winding direction, the second wire being wound from the thread end to the thread end in turn around the tenth pole tooth in the first winding direction, around the eleventh pole tooth in the second winding direction, and around the twelfth pole tooth in the first winding direction, the third wire being wound from the thread end to the thread end in turn around the nineteenth pole tooth in the first winding direction, around the twentieth pole tooth in the second winding direction, and around the twenty-first pole tooth in the first winding direction, the fourth wire being wound from the thread end to the thread end in turn around the fourth pole tooth in the first winding direction, around the fifth pole tooth in the second winding direction, and around the sixth pole tooth in the first winding direction, the fifth electric wire is wound to the tail from the head of the wire sequentially along the first winding direction around the thirteenth polar tooth, along the second winding direction around the fourteenth polar tooth and along the first winding direction around the fifteenth polar tooth, the sixth electric wire is wound to the tail from the head of the wire sequentially along the first winding direction around the twelfth polar tooth, along the second winding direction around the thirteenth polar tooth and along the first winding direction around the twenty-fourth polar tooth, the seventh electric wire is wound to the tail from the head of the wire sequentially along the first winding direction around the seventh polar tooth, along the second winding direction around the eighth polar tooth and along the first winding direction around the ninth polar tooth, the eighth electric wire is wound to the tail from the head of the wire sequentially along the first winding direction around the sixteenth polar tooth, along the second winding direction around the seventeenth polar tooth and along the first winding direction around the eighteenth polar tooth, and the ninth electric wire is wound from the head of the ninth electric wire sequentially along the first winding direction around the twenty-fifth polar tooth, the wire ends are wound around the twenty-sixth pole tooth in the second winding direction and around the twenty-seventh pole tooth in the first winding direction, and the wire ends of the first to third electric wires are electrically connected, the wire ends of the fourth to sixth electric wires are electrically connected, the wire ends of the seventh to ninth electric wires are electrically connected, and the wire ends of the first to ninth electric wires are electrically connected to form a common terminal. The rotor comprises a rotor skeleton and 30 sheet-shaped permanent magnets. The rotor frame is cylindrically annular and defines a rotor cavity therein. The 30 sheet-like permanent magnets are arranged in the rotor cavity at intervals in the circumferential direction.

For example, in some embodiments, the diameters of the first through ninth wires are in the range of 0.75-1.2mm, the teeth of the core have tooth gaps at the radially outer ends, the tooth gaps are in the range of 1.8-2.5mm, and the rotor has a pole arc coefficient in the range of 0.65-0.9. The polar arc coefficient refers to the ratio between the central angle of a single permanent magnet relative to the longitudinal axis of the rotor and 12 degrees.

For example, in some embodiments, the height of the permanent magnets is 1-2mm less than the height of the stator core.

For example, in some embodiments, the air gap between the outer circle of the stator and the inner circle of the rotor is in the range of 0.3-0.5.

For example, in some embodiments, the spacing distance between the permanent magnets is greater than 1.4mm.

For example, in some embodiments, the stator further includes a rigid short circuit member including a short circuit body and 9 wire portions connected to the short circuit body and arranged at intervals in the circumferential direction. The wire tails of the first to ninth electric wires are electrically and mechanically connected to the 9 wire connection portions, respectively, and the short-circuiting body electrically connects the 9 wire connection portions to form common terminals of the first to ninth electric wires.

For example, in some embodiments, the shorting body is a copper ring. The 9 first wire connecting portions are 9 tabs extending radially outwardly from the copper ring. The wire tails of the first to ninth electric wires are respectively hung and welded to the 9 tabs to form common ends of the first to ninth electric wires.

For example, in some embodiments, the stator further comprises a stator skeleton. The shorting body of the shorting member is a first PCB board including a first conductive trace disposed thereon. The 9 first wiring portions include pins fixed into and protruding from the stator bobbin, the pins being inserted and soldered into the soldering holes of the first PCB board to be electrically connected to the first conductive traces, thereby forming common ends of the first to ninth electric wires.

For example, in some embodiments, the shorting body is a first PCB board in the shape of a circular ring disk including a first conductive trace disposed thereon. The 9 first wire connecting portions include a first recess recessed from a circumferential edge of the first PCB board and a first conductive material provided at the first recess to be electrically connected to the first conductive trace, and the wire tail is placed in the first recess and soldered to the first conductive material, thereby forming common ends of the first to ninth electric wires.

For example, in some embodiments, the stator further includes a circuit connecting member including a connecting body and 9 second wire portions. The connecting body is a second PCB board including a plurality of second conductive traces disposed thereon. The 9 second wire connecting portions include second recessed portions recessed from a circumferential edge of the second PCB board and a second conductive material provided at the second recessed portions to be electrically connected to the respective second conductive traces, and wire stubs are placed in the respective second recessed portions and soldered to the respective second conductive materials to achieve electrical connection of the first to third electric wires, electrical connection of the fourth to sixth electric wires, and electrical connection of the seventh to ninth electric wires.

For example, in some embodiments, the first through ninth wires are single enameled wires.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present disclosure and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings may be obtained from the drawings without inventive effort.

Fig. 1 is a perspective view of a stator according to an embodiment of the present disclosure;

FIG. 2 is an exploded perspective view of the stator of FIG. 1;

FIG. 3 is a top view of the stator of FIG. 1;

fig. 4 is a schematic view of the wire connections of the coil assembly of the stator of fig. 1;

fig. 5 is a plan view of a circuit connecting member of the stator of fig. 1;

FIG. 6 is a perspective view of a shorting member of the stator of FIG. 1;

fig. 7 is an exploded perspective view of a stator according to another embodiment of the present disclosure;

fig. 8 is a top view of a stator according to yet another embodiment of the present disclosure;

FIG. 9 is a perspective view of a rotor according to an embodiment of the present disclosure;

FIG. 10 is a plan view of the rotor of FIG. 9;

FIG. 11 is an enlarged view of the dashed box portion of FIG. 10;

FIG. 12 is an exploded perspective view of the rotor of FIG. 9;

FIG. 13 is a perspective view of the magnetic isolation bridge of the rotor of FIG. 9;

FIG. 14 is a plan view of the magnetic isolation bridge of the rotor of FIG. 9;

FIG. 15 is a cross-sectional view of a 27 slot 30 pole in-wheel motor according to one embodiment of the present disclosure;

FIG. 16 is a cogging torque for a hub motor including a conventional 27 slot 30 pole; and is

Fig. 17 is a cogging torque for a 27 slot 30 pole hub motor according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, a hub motor according to an embodiment of the present disclosure is described in detail with reference to the accompanying drawings. To make the objects, technical solutions and advantages of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are some, but not all embodiments of the present disclosure.

Thus, the following detailed description of the embodiments of the present disclosure, presented in connection with the drawings, is not intended to limit the scope of the disclosure, as claimed, but is merely representative of selected embodiments of the disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

The singular forms include the plural unless the context otherwise dictates otherwise. Throughout the specification, the terms "comprises," "comprising," "has," "having," "includes," "including," "having," "including," and the like are used herein to specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.

In addition, even though ordinal terms such as "first," "second," etc., are used to describe various elements, the elements are not limited by the terms, and the terms are used only to distinguish one element from another.

SUMMARY

Embodiments of the present disclosure provide an in-wheel motor in which efficiencies of a stator and a rotor are respectively improved, and parameters such as a diameter of a wire in a coil block of the stator, a tooth gap, and a pole arc coefficient of the rotor, which are related to each other, are optimized, thereby achieving maximization of motor efficiency and reduction of manufacturing costs.

Stator with a stator core

Generally, under the condition that the performances of all parts are not changed, in order to improve the efficiency of the motor, the most effective mode is to improve the slot filling rate of a coil assembly of a stator and reduce the loss of copper, but the stator of the conventional hub brushless motor has the defects of low yield, poor safety, low efficiency, high electromagnetic noise and low production efficiency.

The winding of every phase place in current wheel hub brushless motor's stator comprises the coil of establishing ties (promptly, series connection winding), and series connection winding needs to make the winding with the very big copper line of single diameter, however, because the restriction of stator core mechanical design size, leads to the enameled wire that can't wind single major diameter (> 1.3 mm) on the iron core, and the adoption is thinner stranded wire instead and is merged into one, goes to the wire winding again.

However, the winding process of the multi-strand thin wire includes that the single-strand thin wire is drawn out from the wire barrel under the tension of the winding machine, then combined into one strand through the combining clamp, passed through the flying fork of the winding machine, and finally slid into the stator core slot through the winding clamp. In the process, the insulation skin is easy to damage to cause short circuit and breakdown of the winding, and the motor is damaged.

In addition, the stator winding process comprises the steps of leading out a plurality of strands of thin wires from a wire barrel, then combining the thin wires into a strand of wire harness, leading the strand of wire harness to the flying fork position of the flying fork winding machine, and then sliding the combined strand of wire harness into the stator winding position through the flying fork jig for winding. Because the fine rule of stranded merges together and must slide into the line containing groove of stator through the fly fork tool, because of the radius difference of inner and outer lane when the fine rule of stranded twines simultaneously, the line speed of crossing of different strands of fine rule between the tool is different. The tension in the wire wound around the outer ring is greater than the tension in the wire wound around the inner ring. Furthermore, the wire of the outer ring is tightly wound due to the large tension, while the wire of the inner ring is loosely wound, so that part of the inner ring is locally extruded out of the outer ring, and the whole coil is disorderly and disorderly wound. This results in low slot fill factor and low motor efficiency, and greatly affects the inductance and driving efficiency after power-on, and is also the source of electromagnetic noise.

Moreover, the action force of mutual friction and extrusion is generated when a plurality of strands of thin wires are wound together, so that the winding machine can only perform winding at a very slow speed (one turn in 2-4 seconds), the production efficiency is seriously influenced, but the problems of wire damage and insulation can be generated when the winding speed is accelerated, and the motor can generate serious potential safety hazard under the condition of high load.

Therefore, in order to improve the efficiency of the motor, and the noise, safety, yield and production efficiency of the motor. There is a need for an improved stator which is an important part of an in-wheel motor.

Fig. 1 is a perspective view of a stator according to an embodiment of the present disclosure, fig. 2 is an exploded perspective view of the stator in fig. 1, and fig. 3 is a top view of the stator in fig. 1.

As shown in fig. 1 to 3, the stator includes a shaft 110, a stator bobbin 120, a stator core 130, a coil assembly 140, a circuit connection member 150, and a short circuit member 160.

The stator core 130 includes a

stator body

133 and 27 pole teeth 131 extending radially outward from the stator body 133, the 27 pole teeth 131 respectively including first to twenty-seventh pole teeth 131 arranged in order in a circumferential direction. The numbering of the teeth 131 is shown next to the corresponding tooth 131 in fig. 3. The stator frame 120 serves to electrically insulate the pole teeth 131 of the stator core 130. Alternatively, the pole teeth 131 of the stator core 130 may also be electrically insulated by coating with an insulating material.

The coil assembly 140 includes a first phase coil set for flowing a first phase current, a second phase coil set for flowing a second phase current, and a third phase coil set for flowing a third phase current. The first-phase coil group includes a first-phase first branch, a first-phase second branch, and a first-phase third branch, which are respectively wound by a single first wire 141, a single second wire 142, and a single third wire 143. The second phase coil set includes a second phase first branch, a second phase second branch, and a second phase third branch, which are wound by a single fourth wire 144, a single fifth wire 145, and a single sixth wire 146, respectively. The third phase coil set includes a third phase first branch, a third phase second branch and a third phase third branch, which are respectively wound by a single seventh electric wire 147, a single eighth electric wire 148 and a single ninth electric wire 149.

Specifically, as shown in fig. 3, the first to ninth electric wires 141 to 149 are wound in the following manner: the first electric wire 141 is wound from the thread end to the thread end in order of the first tooth 131 in the first winding direction, the second tooth 131 in the second winding direction, and the third tooth 131 in the first winding direction. The second electric wire 142 is wound from the thread end to the thread end in the first winding direction around the tenth tooth 131, in the second winding direction around the eleventh tooth 131, and in the first winding direction around the twelfth tooth 131 in this order. The third electric wire 143 is wound from the thread end to the thread end around the nineteenth pole tooth 131 in the first winding direction, around the twentieth pole tooth 131 in the second winding direction, and around the twenty-first pole tooth 131 in the first winding direction in this order. The fourth electric wire 144 is wound from the thread end to the thread end in the first winding direction around the fourth tooth 131, in the second winding direction around the fifth tooth 131, and in the first winding direction around the sixth tooth 131. The fifth electric wire 145 is wound from the thread end to the thread end in order around the thirteenth pole tooth 131 in the first winding direction, around the fourteenth pole tooth 131 in the second winding direction, and around the fifteenth pole tooth 131 in the first winding direction. The sixth wire 146 is wound from the thread end to the thread end in order around the twelfth pole tooth 131 in the first winding direction, around the twenty-third pole tooth 131 in the second winding direction, and around the twenty-fourth pole tooth 131 in the first winding direction. The seventh electric wire 147 is wound from the thread end to the thread end in the first winding direction around the seventh pole tooth 131, in the second winding direction around the eighth pole tooth 131, and in the first winding direction around the ninth pole tooth 131 in this order. The eighth electric wire 148 is wound from the thread end to the thread end in the first winding direction around the sixteenth pole tooth 131, in the second winding direction around the seventeenth pole tooth 131, and in the first winding direction around the eighteenth pole tooth 131. The ninth electric wire 149 is wound from the thread end to the thread end in the first winding direction around the twenty-fifth pole tooth 131, in the second winding direction around the twenty-sixth pole tooth 131, and in the first winding direction around the twenty-seventh pole tooth 131. The first winding direction may be one of clockwise and counterclockwise, and the second winding direction is opposite to the first winding direction. Therefore, each phase coil group is separated by 6 pole teeth 131, and the winding directions of the wires on two adjacent pole teeth 131 in each branch are opposite. Adjacent branches of the coil sets of the same phase are spaced 120 ° apart.

The stubs of the first to third electric wires 141 to 143 are electrically connected as the first phase connection terminal of the first phase coil group, the stubs of the fourth to sixth electric wires 144 to 146 are electrically connected as the second phase connection terminal of the second phase coil group, and the stubs of the seventh to ninth electric wires 147 to 149 are electrically connected as the third phase connection terminal of the third phase coil group. The tails of the first to ninth electric wires 141 to 149 are electrically connected to form a common terminal.

Because the stator adopts a single wire to form the coil assembly 140, the stator winding process is greatly simplified, and the automatic and mass production is facilitated. In addition, since the coil assembly 140 is formed by a single wire, friction and extrusion force between wires are reduced during winding, reliability of the wire is increased, and damage to the insulation sheath of the wire, which may occur when a plurality of strands form the coil assembly 140, is avoided. In addition, since the coil assembly 140 is formed by a single wire, the wire is wound more neatly, and disorder of the coil assembly 140 due to a difference in tension between the plurality of strands in the case where the coil assembly 140 is formed by a plurality of strands are avoided. Further, the slot fill ratio of the coil assembly 140 is improved (e.g., about 35%), the inductance and the driving efficiency are improved, and the electromagnetic noise is reduced. Moreover, because a single wire is adopted to form the coil assembly 140, the winding speed is higher than that of the case that a plurality of strands are adopted to form the coil assembly 140, and the production efficiency is improved. Finally, the floor area of equipment for winding a single wire is reduced, and efficient arrangement of a production line is facilitated.

In order to cooperate with the use of a single wire to maximize motor efficiency, a particular winding pattern is used for the 27 slot stator as described above. Fig. 4 is a schematic diagram of the wire connection of the coil assembly 140 of the stator of fig. 1, wherein the numbers in the squares correspond to the numbers of the pole teeth 131. A first phase coil set 1401 including a first phase first branch 1410, a first phase second branch 1420, and a first phase third branch 1430 is shown in fig. 4; a second phase coil set 1402 including a second phase first branch 1440, a second phase second branch 1450, and a second phase third branch 1460; and a third phase coil set 1403 including a third phase first branch 1470, a third phase second branch 1480, and a third phase third branch 1490. Fig. 4 also shows a first phase connection end 140a, a second phase connection end 140b, a third phase connection end 140d and a common end 140d.

As shown in fig. 4, since there are 3 wires connected in parallel with each other, with such a winding manner, even if a single wire is used to wind the coil block 140, the requirement of the stator for the current carrying capacity can be satisfied. Furthermore, not only the above-described specific winding pattern, including the direction of coil winding, the arrangement of the pole teeth 131 in each branch in each phase, in cooperation with a single wire, maximizes the efficiency of the motor to which the stator is mounted. By the winding mode, the requirement of the 27-slot stator for the electric bicycle on efficiency can be met without adopting a single wire with a large diameter.

Under the condition of the same specification size, compared with a conventional stator, the motor using the stator of the embodiment of the disclosure has higher power, and the motor efficiency is improved.

In this example, the first to ninth electric wires 141 to 149 are single enameled wires. Unlike a wire harness composed of a plurality of electric wires, the exterior of a single electric wire is covered with a single insulating sleeve. In a wire harness composed of a plurality of electric wires, the plurality of electric wires are respectively covered by insulating sleeves and combined into a wire harness at the time of winding. For example, the enamel wire may be of a high temperature type.

Further, the diameters of the first to ninth electric wires 141 to 149, the gap of the pole teeth 131 of the core 130, and the like are optimized to further improve the efficiency of the stator.

For example, the diameters of the first to ninth wires 141 to 149 may be in the range of 0.75 to 1.2 mm. By setting the diameters of the individual first to ninth electric wires 141 to 149 within the range of 0.75 to 1.2mm, the stator efficiency is maximized. In one aspect, during winding of the coil assembly 140, the flying fork jig is placed in the gap between the teeth 131 and the wire is wound by sliding the wire along the flying fork jig into the gap. Therefore, the gap between the teeth 131, particularly the gap between the teeth 131 at the radially outer end of the teeth 131 (the tooth gap 132), limits the diameter of the wire. While an excessively large tooth gap 132 leads to magnetic leakage, which in turn leads to a reduction in the stator efficiency. Therefore, the diameter of the wire cannot be made excessively large. On the other hand, although the efficiency of a stator composed of a single wire has been improved by optimizing the winding manner, it is still necessary to increase the diameter of the wire as much as possible to improve the efficiency. Therefore, the diameter of the wire cannot be too small. The diameters of the first to ninth electric wires 141 to 149 of the single wire are set in the range of 0.75 to 1.2mm by balancing the influence of the diameter of the single wire on the efficiency of the stator, thereby achieving the maximization of the stator efficiency.

For example, the teeth 131 of the core 130 have a tooth gap 132 at the radially outer end, the tooth gap 132 being in the range of 1.8-2.5 mm. By setting the tooth gap 132 of the teeth 131 of the core 130 at the radially outer end in the range of 1.8-2.5mm, an optimization of the stator efficiency and production efficiency trade-off is achieved. When the pole tooth gap 132 at the radially outer end is less than 1.8mm, the winding difficulty increases, which may cause a reduction in production efficiency and mechanical damage, such as scratching, of the individual wires. When the tooth gap 132 at the radially outer end is greater than 2.5mm, the leakage flux between the two teeth 131 increases, causing a decrease in stator efficiency.

In addition, in order to improve the automation level and the production efficiency of manufacturing the stator, the connection manner of the head and the tail of the first to ninth electric wires 141 to 149 is improved.

As shown in fig. 1, in the present embodiment, the circuit connecting member 150 for connecting the terminals of the first to ninth electric wires 141 to 149 includes a connecting body and 9 second wire connecting portions. Fig. 5 is a plan view of the circuit connection member 150 of the stator in fig. 1. As shown in fig. 5, the connection body 151 takes the form of a second PCB (printed circuit board). A second plurality of conductive traces (not shown) are disposed on the second PCB. The stubs of the first to ninth electric wires 141 to 149 are electrically connected to the plurality of second conductive traces to realize the electrical connection of the stubs of the first to third electric wires 141 to 143, the electrical connection of the stubs of the fourth to sixth electric wires 144 to 146, and the electrical connection of the stubs of the seventh to ninth electric wires 147 to 149. The circuit connection member 150 further includes 9 second wiring portions 152. The 9 second wire connection portions 152 include 9 second recesses recessed from a circumferential edge of the second PCB board and a second conductive material disposed at the 9 second recesses to be electrically connected to the second conductive traces. The 9 second concave portions are arranged at intervals in the circumferential direction so as to correspond to positions where the stubs of the first to ninth electric wires are located. The stubs of the first to ninth electric wires 141 to 149 may be automatically or manually placed in the 9 second recesses and soldered into the corresponding second recesses, respectively, to achieve the electrical connection through the second conductive trace as described above. In this example, the second recessed portion is recessed from an outer peripheral edge of the second PCB board. In other examples, the second recessed portion may also be recessed from an inner peripheral edge of the second PCB board. The circuit connecting member 150 is fixed to the stator frame 120 by a fastener such as a screw.

For the electrical connection of the common terminal 140d, in the embodiment of the present disclosure, the wire tails of the first to ninth electric wires 141 to 149 may be connected using a dedicated short circuit member 160 to form the common terminal 140d. The shorting member 160 is rigid. That is, the short circuit member 160 has no flexibility and is not deformed by an accidental touch. Further, the short circuit member 160 further includes a short circuit body and 9 first wire connection portions connected to the short circuit body and arranged at intervals in the circumferential direction, the wire tails of the first to ninth electric wires 141 to 149 being electrically and mechanically connected to the 9 first wire connection portions, respectively, the short circuit body electrically connecting the 9 first wire connection portions to form the common end 140d of the first to ninth electric wires 141 to 149.

In the conventional stator, the common terminal 140d is generally formed by stripping the enamel wire at the wire ends of the 9 electric wires, impregnating the 9 wire ends with tin, twisting the 9 wire ends together, and then covering the 9 wire ends with a high-temperature insulating sleeve. Such a method of forming the common terminal 140d is disadvantageous for automated production. In some embodiments of the present disclosure, the common end 140d is formed by connecting 9 wire tails using a rigid shorting member 160. Because shorting member 160 is rigid, it is advantageous to connect the wire tails of wires 141-149 to shorting member 160 by automated equipment to form common end 140d. Further, since 9 first wire connection portions are arranged at intervals in the circumferential direction and electrically connected by the short-circuiting body, it is possible to provide 9 first wire connection portions in the vicinity of the pole teeth 131 on which the respective electric wires are wound last to reduce the length of the wire tail, thereby reducing the stator harmonic component and improving the reliability of the stator.

Fig. 6 is a perspective view of the short circuit member 160 of the stator of fig. 1. As shown in fig. 6, the short circuit body of the short circuit member 160 is an annular body 161, and the 9 first wire portions are 9 tabs 162 extending radially outward from the annular body 161. For example, the shorting member 160 may be a unitary piece made of a conductive material such as copper or a copper alloy. The tails of the first to ninth electric wires 141 to 149 are respectively hung and welded to the 9 tabs 162 to form a common end 140d. The tails of the first through ninth electrical wires 141-149 may be automatically hung onto the respective tabs 162 using automated equipment and then automatically welded to the tabs 162, such as by resistance welding. And the enameled wire is melted while welding, so that the enameled wire stripping step is omitted. Therefore, it is advantageous to simplify and automate the manufacturing process of the stator. For example, the tabs 162 may extend outwardly from the outer peripheral wall of the annular body 161 and at an angle in the range of 20-45 degrees from the longitudinal axis of the annular body 161. Such an angle formed by the tabs 162 and the longitudinal axis of the annular body 161 helps facilitate hooking of the wire tail onto the tabs 162 and reduces the likelihood of the wire tail falling off. The reliability of the stator is improved, and the automation difficulty is reduced. The ring-shaped body 161 may be disposed inside the 27 teeth 131 in the radial direction and at one end of the 27 teeth 131 in the axial direction. The tabs 162 may be disposed between adjacent teeth 131 and extend outward along the longitudinal axis. The annular body 161 may be fixed to the stator frame 120 by interference fit or injection molded into the stator frame 120. In the present example, the shorting member 160 may be mounted to the stator frame 120 prior to forming the coil assembly 140.

Fig. 7 is an exploded perspective view of a stator according to another embodiment of the present disclosure. The stator shown in fig. 7 differs from the stators shown in fig. 1-6 in the configuration of the shorting member. As shown in fig. 7, the shorting body of the shorting member 160 'is a first PCB board 161' of a circular ring disk shape including a first conductive trace (not shown) disposed thereon. The 9 first wiring portions 162' take the form of pins, which are fixed into the stator frame 120 and protrude from the stator frame 120. The 9 first wire connection portions 162 'are soldered to the first PCB board 161' to be electrically connected to the first conductive traces, thereby forming the common ends 140d of the first to ninth electric wires 141 to 149 through the first conductive traces. The 9 first wire portions may be injection-molded with the stator frame 120 or inserted into the corresponding mounting holes of the stator frame 120 by interference fit. The wire tail may be automatically soldered to the first wiring portion 162 'using an automated device, and then the first PCB board 161' is soldered and fixed to the first wiring portion 162 'to electrically connect the first wiring portion 162' and the first conductive trace, thereby forming the common terminal 140d. As shown in fig. 7, the first PCB board 161 'may be fixed to the stator frame 120 using screws 163'. In this example, the first wiring portion 162' is in the form of a pin, which is inserted and soldered into the soldering hole 1611' of the first PCB board 161 '. Therefore, the use of the short circuit member 160' composed of the first PCB board 161' and the first wire part 162' fixed into the stator frame 120 and protruding from the stator frame 120 helps to simplify and automate the manufacturing process of the stator. In this example, the first wiring portion 162 'may be mounted to the stator frame 120 before the coil assembly 140 is formed, and the first PCB board 161' may be mounted to the stator frame 120 after the coil assembly 140 is formed.

Fig. 8 is a perspective view of a stator according to yet another embodiment of the present disclosure. The stator shown in fig. 8 differs from the stator shown in fig. 1-6 in the construction of the shorting member 160. As shown in fig. 8, the shorting body of the shorting member 160 is a first PCB board 161 ″ in the shape of a circular ring disk including a first conductive trace disposed thereon. The 9 first wire connecting portions 162 ″ include a first recess portion recessed from an outer peripheral edge of the first PCB board and a second conductive material disposed at the first recess portion to be electrically connected to the conductive traces to form a common end 140d of the first to ninth electric wires 141 to 149. The wire tail may be disposed into the first recess either manually or automatically using automated equipment and then soldered to the first conductive material at the first recess, thereby forming the common end 140d. Therefore, using the short circuit member 160 composed of the first PCB board 161 ″, the first recess portion, and the first conductive material at the first recess portion helps to simplify and automate the manufacturing process of the stator. In this example, the first PCB board 161 ″ and the 9 first wire connection portions 162 ″ may be mounted to the stator frame 120 after the coil assembly 140 is formed. The first PCB board 161 "is fixed to the stator frame 120 by screws 163".

Rotor

In order to improve the motor efficiency, it is also necessary to improve the rotor, which is an important part of the in-wheel motor.

The rotor includes a plurality of permanent magnets arranged in a circumferential direction, and rotates relative to the stator by interaction of the plurality of permanent magnets with the teeth of the stator around which the coils are wound. In a conventional rotor, the permanent magnets are arranged next to each other with almost no gaps between the permanent magnets. Self-attraction of south poles and north poles of two adjacent permanent magnets forms a self-loop, and the magnetic field of the part cannot be used for an effective magnetic circuit of the motor, belongs to a useless magnetic circuit and causes waste. Also, there is a magnetic saturation region at the surface where the adjacent permanent magnets face each other, additional harmonics and vibration are generated, deteriorating the motor performance.

The rotor according to the embodiment of the present disclosure has appropriate gaps between the permanent magnets, and effectively avoids the magnetic saturation effect. Therefore, harmonic waves and vibration caused by the magnetic saturation effect are avoided, and motor noise is reduced. In addition, the volume of the permanent magnet is reduced, so that the material usage amount and the cost of the permanent magnet are reduced, and rare earth resources are indirectly protected.

Fig. 9 is a perspective view of a rotor according to an embodiment of the present disclosure, fig. 10 is a plan view of the rotor in fig. 9, fig. 11 is an enlarged view of a dotted frame portion in fig. 10, and fig. 12 is an exploded perspective view of the rotor in fig. 9. As shown in fig. 9-12, the rotor includes a hub main body 210, a flux ring 220 disposed inside the cylindrical wall of the hub main body 210, a first bearing 250 mounted to the central hole of the hub main body 210, a plurality of permanent magnets 230, and a magnetic isolation bridge 240. In order to clearly show the structure of the inside of the rotor, fig. 9-12 do not show a hubcap closing the opening of the hub body 210 and a second bearing installed at the center hole of the hubcap. The hub body 210 and the hub cover together constitute a hub shell to define an inner space of the rotor, i.e., a rotor cavity. The hub body 210 and the hub cover may be made of an aluminum alloy material. The magnetic conductive ring 220 may be an iron ring for guiding the magnetic circuit of the permanent magnet 230. The plurality of permanent magnets 230 are arranged inside the flux ring 220 in the circumferential direction and are bonded to the flux ring 220.

Fig. 13 is a perspective view of the magnetic shield bridge 240 of the rotor in fig. 9, and fig. 14 is a plan view of the magnetic shield bridge 240 of the rotor in fig. 9. As shown in fig. 13 and 14, the magnetism isolating bridge 240 includes an annular body 241 and magnetism isolating arms 242 extending in an axial direction from the annular body 241. Returning to fig. 9-12, the plurality of permanent magnets 230 are arranged spaced apart from each other, and the magnetism isolating arms 242 of the magnetism isolating bridge 240 are inserted between the adjacent permanent magnets 230 to maintain the arrangement in which the permanent magnets 230 are spaced apart from each other. In other words, the permanent magnets 230 are inserted into the recesses formed by the magnetism isolating arms 242 of the magnetism isolating bridge 240 to be spaced apart from each other, thereby being arranged to be spaced apart from each other. In this embodiment, the rotor is used for a 27 slot 30 pole hub motor. The rotor includes 30 permanent magnets 230.

The permanent magnet 230 is made of, for example, a sintered aluminum-iron-boron material, is plate-shaped, and is preferably arc-shaped plate-shaped to follow the shape of the annular magnetic conductive ring 220. For example, two surfaces of the permanent magnet 230 facing the circumferential direction are parallel to each other. In this example, the central angle of the permanent magnet 230 with respect to the longitudinal axis of the rotor remains constant in the axial direction. In other examples, the two surfaces of the permanent magnet 230 facing the circumferential direction are not parallel to each other. For example, the permanent magnet 230 is a trapezoidal sheet. In this example, the central angle of the permanent magnets 230 with respect to the longitudinal axis of the rotor varies in the axial direction. The central angle of the permanent magnets with respect to the longitudinal axis of the rotor is defined as the maximum measured central angle.

The power of the motor is divided into two parts, one part is useful work, the other part is useless work, and the efficiency of the motor refers to the ratio of the useful work to the total power. The more useful work fraction the motor, the higher the efficiency of the motor. The power consumed in the magnetic saturation region at the surface (i.e., the surface facing the circumferential direction) where the adjacent permanent magnets 230 face each other is useless work, and therefore, it is necessary to minimize the magnetic saturation intensity, and the distance between the N-pole magnet and the S-pole magnet of the adjacent permanent magnets 230 is positively correlated with the magnetic saturation intensity. For example, in the present example, with 30 permanent magnets 230, there are 15 pairs of saturation regions of the NS pole, which are circumferentially distributed in the rotor field, and the magnetic fields in these saturation regions are all such as to impede the flow of the useful work portion field during normal operation of the machine. Therefore, it is necessary to select a proper gap between the permanent magnets 230 to optimize the magnetic path arrangement between the permanent magnets 230, thereby maximizing the motor efficiency.

Here, a polar arc coefficient is defined, which refers to the ratio between the central angle θ (see fig. 14) of a single permanent magnet 230 with respect to the longitudinal axis of the rotor and the angle of the magnetic poles of the rotor, which is 360 degrees divided by the number of permanent magnets 230. In the present example, the angle of the magnetic poles of the rotor is 12 °. The embodiment of the disclosure sets the pole arc coefficient within the range of 0.65-0.9, and realizes the optimization of the motor efficiency. When the pole arc coefficient is greater than 0.9, the magnetic saturation effect cannot be effectively avoided and material waste is caused, and it is difficult to accurately maintain a small gap between the permanent magnets 230. When the pole arc coefficient is less than 0.65, the magnetic density is too small to meet the requirements of the motor on current and power.

Further, the spacing distance between the permanent magnets 230 is greater than 1.4mm in consideration of the influence of the overall size of the rotor on the arrangement of the magnetic circuit.

Hub motor

At least one embodiment of the present disclosure provides an in-wheel motor including a stator and a rotor. The stator may be a stator as described above, and the rotor may be a rotor as described above.

As described above, the diameter of the wire, the tooth gap, and the pole arc coefficient are correlated with each other, collectively affecting the motor efficiency. In particular, the cooperation between the pole arc coefficient of the rotor and the pole tooth gap of the stator affects the cogging of the motor. The diameter of the motor and the tooth gap influence each other and are restricted to each other. According to the in-wheel motor disclosed by the embodiment of the disclosure, the pole arc coefficient of the rotor, the diameter of the wire in the stator and the pole tooth gap are reasonably set, so that the cogging torque and the noise caused by the magnetic saturation area of the motor are reduced, the harmonic component of the motor is reduced, and the efficiency of the motor is improved.

Fig. 15 is a cross-sectional view of a 27 slot 30 pole in-wheel motor according to an embodiment of the present disclosure. As shown in fig. 15, the motor includes a rotor and a stator. As described above, the stator includes the shaft 110, the stator core 130 fixed to the shaft 110 and including 27 pole teeth, and the coil assembly 140 wound on the pole teeth. As described above, the rotor includes the hub shell having the hub main body 210 and the hub cover 260, the flux ring 220, the 30 permanent magnets 230, the first bearing 250 fixed to the hub main body 210, and the second bearing 270 fixed to the hub cover. The shaft 110 of the stator is supported on a first bearing 250 and a second bearing 270 so that the rotor can rotate relative to the stator.

The coil block 140 of the stator may be formed by winding the first to ninth electric wires 141 to 149 on the 27 pole teeth 131 of the stator core 130 in a specific manner as described above. The 30 permanent magnets 230 of the rotor may be arranged spaced apart from each other via magnetic isolation bridges 240 as described above. The first to ninth wires 141 to 149 have a diameter in the range of 0.75 to 1.2mm, the teeth 131 of the core 130 have a tooth gap 132 in the range of 1.8 to 2.5mm at the radially outer end, and the rotor has a pole arc coefficient in the range of 0.65 to 0.9. Such a configuration of wire diameter, tooth gap and pole arc factor allows maximization of motor efficiency.

In addition, in this hub electrode, the air gap 300 (shown as thick black line in fig. 15) between the outer circumference of the stator (i.e., the outer circumference of the core 130) and the inner circumference of the rotor (i.e., the inner circumference of the permanent magnet) is in the range of 0.3-0.5mm, which, in cooperation with the above-mentioned parameters of the wire diameter, the tooth gap, and the pole arc coefficient, further optimizes the motor efficiency.

In this example, the height of the permanent magnet 230 is the same as the height of the stator core 130. In other examples, permanent magnet 230 is 1-2mm lower than the height of stator core 130. In this example, even if the height is less than that of the stator core 130, the permanent magnet 230 can generate a sufficient magnetic field at its end to be fitted to the stator core 130. The reduced volume of the permanent magnet 230 reduces the material usage and cost of the permanent magnet, protecting the rare earth resources.

The spacing distance between the permanent magnets 230 is greater than 1.4mm in consideration of the influence of the overall size of the motor on the arrangement of the magnetic circuit.

Fig. 16 is a cogging torque of a hub motor including a conventional 27-slot 30-pole, and fig. 17 is a cogging torque of a hub motor including a 27-slot 30-pole according to an embodiment of the present disclosure. As shown in fig. 16 and 17, the cogging torque of the motor according to the embodiment of the present disclosure is reduced from about 0.16N · m to about 0.06N · m, compared to the motor including the conventional rotor. The cogging torque can reflect the magnitude of the useless work of the motor in a magnetic saturation area. It can be seen that the motor of the embodiments of the present disclosure achieves improved motor efficiency and reduced noise.

The above-mentioned embodiments only express several implementation modes of the present disclosure, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present disclosure. It should be noted that various changes and modifications can be made by one skilled in the art without departing from the spirit of the disclosure, and these changes and modifications are all within the scope of the disclosure. Therefore, the protection scope of the present disclosure should be subject to the appended claims.

Claims

1. An in-wheel motor, comprising:

a stator, the stator comprising:

a stator core including a stator body and 27 pole teeth extending radially outward from the stator body, the 27 pole teeth including first to twenty-seventh pole teeth sequentially arranged in a circumferential direction;

a coil assembly comprising:

a first phase coil assembly comprising:

a first phase first branch including a single first wire;

a first phase second branch including a single second wire; and

a first phase third branch comprising a single third wire;

a second phase coil set comprising:

a second phase first branch including a single fourth wire;

a second phase second branch comprising a single fifth wire; and

a second phase third branch comprising a single sixth wire;

a third phase coil assembly comprising:

a third phase first branch comprising a single seventh wire;

a third phase second branch comprising a single eighth wire; and

a third phase third branch comprising a single ninth wire,

wherein,

the first electric wire is wound to the tail end from the head end in sequence around the first pole tooth along a first winding direction, around the second pole tooth along a second winding direction opposite to the first winding direction and around the third pole tooth along the first winding direction,

the second electric wire is wound to the tail of the wire from the head of the wire in sequence along the first winding direction around the tenth pole tooth, along the second winding direction around the eleventh pole tooth and along the first winding direction around the twelfth pole tooth,

the third electric wire is wound to the tail end from the wire head in sequence along the first winding direction around the nineteenth pole tooth, along the second winding direction around the twentieth pole tooth and along the first winding direction around the twenty-first pole tooth,

the fourth electric wire is wound to the tail of the wire from the head of the wire in sequence along the first winding direction around the fourth pole tooth, along the second winding direction around the fifth pole tooth and along the first winding direction around the sixth pole tooth,

the fifth electric wire is wound from the wire head to the wire tail sequentially along the first winding direction around the thirteenth pole tooth, along the second winding direction around the fourteenth pole tooth and along the first winding direction around the fifteenth pole tooth,

the sixth electric wire is wound from the wire head to the wire tail sequentially along the first winding direction around the twenty-second twelve-pole tooth, along the second winding direction around the twenty-third thirteen-pole tooth and along the first winding direction around the twenty-fourth pole tooth,

the seventh electric wire is wound to the tail from the head of the wire in turn around the seventh pole tooth along the first winding direction, around the eighth pole tooth along the second winding direction and around the ninth pole tooth along the first winding direction,

the eighth electric wire is wound to the tail from the head of the wire in turn around the sixteenth pole tooth along the first winding direction, around the seventeenth pole tooth along the second winding direction and around the eighteenth pole tooth along the first winding direction,

the ninth electric wire is wound to the tail from the head in turn around the twenty-fifth pole tooth in the first winding direction, around the twenty-sixth pole tooth in the second winding direction, and around the twenty-seventh pole tooth in the first winding direction, and

the first to third electric wires have their heads electrically connected, the fourth to sixth electric wires have their heads electrically connected, the seventh to ninth electric wires have their heads electrically connected, and the first to ninth electric wires have their tails electrically connected to form a common terminal; and

a rotor, the rotor comprising:

a rotor frame having a cylindrical ring shape and defining a rotor cavity therein;

and 30 sheet-like permanent magnets arranged in the rotor cavity at intervals in the circumferential direction.

2. The in-wheel motor of claim 1, wherein

The diameters of the first to ninth electric wires are in the range of 0.75-1.2mm,

the teeth of the core have a tooth gap at the radially outer end, the tooth gap being in the range of 1.8-2.5mm, and

the rotor has a polar arc coefficient in the range of 0.65-0.9, which refers to the ratio between the central angle of a single permanent magnet with respect to the longitudinal axis of the rotor and 12 degrees.

3. The in-wheel motor according to claim 1 or 2,

the height of the permanent magnet is 1-2mm smaller than that of the stator core.

4. The in-wheel motor according to claim 1 or 2,

the air gap between the outer circle of the stator and the inner circle of the rotor is in the range of 0.3-0.5.

5. The in-wheel motor according to claim 1 or 2,

the spacing distance between the permanent magnets is greater than 1.4mm.

6. The in-wheel motor according to claim 1 or 2, wherein the stator further comprises:

a rigid short circuit member including a short circuit body and 9 wire connection portions connected to the short circuit body and arranged at intervals in a circumferential direction, the wire tails of the first to ninth electric wires being electrically and mechanically connected to the 9 wire connection portions, respectively, the short circuit body electrically connecting the 9 wire connection portions to form a common end of the first to ninth electric wires.

7. The in-wheel motor of claim 6,

the short-circuit body is a copper ring,

the 9 first wire portions are 9 tabs extending radially outward from the copper ring,

the wire tails of the first to ninth electric wires are respectively hung and welded to 9 tabs to form common ends of the first to ninth electric wires.

8. The in-wheel motor of claim 6,

the stator further comprises a stator frame, wherein,

the shorting body of the shorting member is a first PCB board including a first conductive trace disposed thereon,

the 9 first wire connecting portions include pins fixed to and protruding from the stator bobbin, the pins being inserted and soldered into the soldering holes of the first PCB board to be electrically connected to the first conductive traces, thereby forming common ends of the first to ninth electric wires.

9. The in-wheel motor of claim 6,

the shorting body is a first PCB board in the shape of a circular ring disk, including a first conductive trace disposed thereon,

the 9 first wire connecting portions include a first recess recessed from a circumferential edge of the first PCB board and a first conductive material provided at the first recess to be electrically connected to the first conductive trace, and the wire tail is placed in the first recess and soldered to the first conductive material, thereby forming a common end of the first to ninth electric wires.

10. An in-wheel motor according to claim 1 or 2, wherein

The stator further includes a circuit connection member including a connection body and 9 second wire portions,

the connecting body is a second PCB board including a plurality of second conductive traces disposed thereon,

the 9 second wire connecting portions include second recessed portions recessed from a circumferential edge of the second PCB board and a second conductive material provided at the second recessed portions to be electrically connected to the respective second conductive traces, and the wire stubs are placed in the respective second recessed portions and soldered to the respective second conductive materials to achieve electrical connection of the first to third wires, electrical connection of the fourth to sixth wires, and electrical connection of the seventh to ninth wires.

11. The in-wheel motor according to claim 1 or 2,

the first to ninth electric wires are single enameled wires.