WO2021018063A1

WO2021018063A1 - Motor for handheld electric tool

Info

Publication number: WO2021018063A1
Application number: PCT/CN2020/104664
Authority: WO
Inventors: 吴晓婷
Original assignee: 吴晓婷
Priority date: 2019-07-31
Filing date: 2020-07-25
Publication date: 2021-02-04

Abstract

Disclosed is a motor for handheld electric tool The motor comprises: an integral stator, a plurality of protrusions extending outwardly in a radial direction thereof being arranged at an outer side of the stator; a rotor arranged at an inner side of the stator; an armature shaft coaxially connected to the rotor; a commutator matching and connected to the armature shaft; an electric brush electrically connected to the commutator, wherein an outer diameter of the stator is 40 mm-57 mm, a ratio of an outer diameter of the rotor to the outer diameter of the stator is 0.50-0.62, and a ratio of the height of the protrusion to the thickness of a portion of the stator at which the protrusion is located is 0.1-0.5. The motor provided in the embodiment of the present invention has a compact structure and an overall reduced weight, and provides higher output performance over motors of the same size.

Description

Motor for hand-held electric tool

Technical field

This application relates to a motor, in particular to a motor for a handheld electric tool.

Background technique

Hand-held electric tools, such as angle grinders, swing machines, etc., require the user to hold the tools to operate the work tools such as cutting, drilling, and polishing on the workpiece. Currently, split stator motors are mostly used to replace conventional integral motors. The stator of the split motor is divided into multiple pieces before winding, and each piece is wound independently, which increases the amount of winding. After the winding is completed, the pieces are spliced or welded together. The split stator winds more coils than the integral stator, which increases the output power of the motor. However, the manufacturing and assembly process of the split stator is more complicated than the monolithic stator, and the manufacturing process is more, and the manufacturing cost is also much higher, which limits its wide use in handheld power tools, and the output of this type of motor Low capacity.

Summary of the invention

Based on the above problems, the present application provides a motor for an electric tool, which has a brush motor with low cost, high power, small size, and an integral stator.

To this end, this application adopts the following technical solutions.

A hand-held electric tool motor, characterized in that it contains

An integral stator, on its outer side is provided with a plurality of convex portions protruding outward in the radial direction;

A rotor, which is arranged inside the stator;

An armature shaft, which is coaxially connected with the rotor;

A commutator, which is matched and connected with the armature shaft;

A brush, which is electrically connected to the commutator;

The outer diameter of the stator is between 40mm～57mm,

The ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.50 and 0.62.

In a preferred embodiment, the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.50 and 0.6.

In a preferred embodiment, the outer diameter of the stator is 46 mm or 48 mm or 50 mm or 52 mm or 55 mm or 57 mm, and the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.55 and 0.62. Preferably, the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.55 and 0.60.

In a preferred embodiment, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.60, and the yoke width of the stator is between 4.4 mm and 5.0 mm.

In a preferred embodiment, the integral stator has four convex portions uniformly arranged in the outer circumferential direction, and the convex portions are symmetrical along the first direction axis or the second direction axis.

In a preferred embodiment, the integral stator is provided with at least two convex portions in the outer circumferential direction.

In a preferred embodiment, the convex portion is integrally formed with the stator, and the thickness of the convex portion is between 3.8 mm and 6.0 mm. At this time, the convex part is sometimes called a stator yoke, and its thickness is thicker than that of the non-protruding part.

In a preferred embodiment, the length of the stator along the axial direction of the armature shaft is between 40 mm and 60 mm.

In a preferred embodiment, the motor further includes a heat dissipating fan, which is coaxially connected to the shaft of the rotor through a connector, and drives the heat dissipating fan to rotate based on the rotation of the shaft; the diameter of the heat dissipating fan is larger than that of the The outer diameter of the rotor, and the ratio of the diameter of the cooling fan to the outer diameter of the rotor is between 1.5-3.

In a preferred embodiment, the ratio of the diameter of the heat dissipation fan to the outer diameter of the stator is between 1.1 and 1.8.

In a preferred embodiment, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.58, and the yoke width of the stator is 3.8 mm to 5.0 m.

An embodiment of the present application also provides a hand-held electric tool motor, which is characterized by including an integral stator, the outer side of which is uniformly arranged with a plurality of convex parts;

A rotor, which is arranged inside the stator;

A heat dissipation fan, which is arranged on one side of the motor and connected to the rotor, and drives the heat dissipation fan to rotate based on the rotation of the rotor;

An armature shaft, which is fixedly connected to the rotor;

A commutator, which is fixedly connected to the armature shaft; a brush, which is electrically connected to the commutator;

The outer diameter of the integral stator ranges from 40 mm to 57 mm, and the ratio of the outer diameter of the rotor to the outer diameter of the stator ranges from 0.55 to 0.62.

In a preferred embodiment, the outer diameter of the stator is 46mm or 48mm or 50mm or 52mm or 55mm or 57mm, and the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.55 and 0.60.

In a preferred embodiment, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.60, and the width of the center yoke of the stator is between 3.6 mm and 4.2 mm.

In a preferred embodiment, the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.58 and 0.60, the thickness of the protrusion is 4.8 mm, and the ratio of the output power of the motor to its volume is between 8 and 12. (Unit w/cm3), preferably, the ratio of the output power of the motor to its volume is between 9-11 (unit w/cm3).

In a preferred embodiment, the convex portion is integrally formed with the stator, and the thickness of the convex portion is between 3.8 mm and 5.0 mm.

In a preferred embodiment, the diameter of the armature shaft is between 6 mm and 8 mm.

In a preferred embodiment, the motor further includes a heat dissipating fan, which is coaxially connected to the shaft of the rotor through a connector, and drives the heat dissipating fan to rotate based on the rotation of the rotor; the diameter of the heat dissipating fan is larger than that of the The outer diameter of the rotor, and the ratio of the diameter of the cooling fan to the outer diameter of the rotor is between 1.5-3.

In a preferred embodiment, the motor is equipped with a pair of tooth width bridges, which are arranged opposite to each other on the outside of the integral stator, and in the axial direction of the stator, the sides on which the tooth width bridges are respectively arranged are parallel.

In a preferred embodiment, the ratio of the height of the protrusion to the thickness of the protrusion is between 0.1 and 0.5.

Compared with the solutions in the prior art, the advantages of this application:

The motor according to the embodiment of the present application has a compact structure, which reduces the overall weight of the motor and improves the heat dissipation effect of the motor while enhancing the effective magnetic flux of the motor under the same size and improving the output capacity.

Description of the drawings

In order to more clearly explain the technical solutions in the embodiments of this specification or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some of the embodiments described in this specification. For those of ordinary skill in the art, without creative labor, other drawings can be obtained from these drawings:

FIG. 1 is a schematic diagram of the stator structure of a motor according to an embodiment of the application;

2 is a schematic cross-sectional view of a stator according to an embodiment of the application;

3 is a schematic cross-sectional view of a stator according to another embodiment of the application;

Fig. 4 is a schematic diagram of the structure of a motor according to an embodiment of the application;

Fig. 5 is a schematic diagram of the B-B cross section of the motor of Fig. 4;

Fig. 6 is a schematic structural diagram of a rotor assembly according to an embodiment of the application;

7 is a schematic cross-sectional view of a rotor assembly according to an embodiment of the application;

Fig. 8 is a schematic cross-sectional view at B of the motor of Fig. 7;

Figure 9 is a schematic cross-sectional view of a rotor according to an embodiment of the application;

FIG. 10 is a schematic diagram of the area of the convex portion and the groove of the motor according to the embodiment of the application.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions proposed by this application, the following will clearly and completely describe the technical solutions in the embodiments of this specification with reference to the drawings in the embodiments of this specification. Obviously, the described The embodiments are only a part of the embodiments in this specification, rather than all the embodiments. Based on one or more embodiments in this specification, all other embodiments obtained by a person of ordinary skill in the art without creative work shall fall within the protection scope of this application.

It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or a central element may also exist. When an element is considered to be "connected" to another element, it can be directly connected to the other element or an intermediate element may also be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only. The outer diameter of the stator mentioned in this embodiment includes the height of the protrusion protruding from the surface of the body. The height of the protrusion ranges from 0.5mm to 3mm (for example, 0.5mm, 1.0mm, 1.5mm, 2.0mm, etc.), depending on the application.

Examples:

Next, the motor of the embodiment of the present application will be described with reference to FIGS. 1 to 9. In addition, the drawings include schematic diagrams, and the scales and ratios of vertical and horizontal of each part may be different from actual ones.

Fig. 1 is a schematic diagram of the structure of the motor stator according to the embodiment of the application. The stator 100 includes a main body 101, a convex portion 102 arranged on the outside of the main body 101, and a horn-shaped salient pole 103 opposite to the inside of the main body 101. The center yoke 104 is configured with the center yoke 104 approximately perpendicular to the center line of the salient pole 103. The ratio of the circumferential length of the center yoke 104 to the thickness of the body 101 at the position is between 0.5-2. Preferably, the circumferential length is slightly equal to the thickness of the body at its location. The circumferential length of the horn-shaped salient pole 103 is equal to the axial length of the stator body, and a winding (also called copper wire/enameled wire, not shown) is wound on it according to a certain rule. The outer contour of the integral stator is circular or other shapes suitable for being housed in the housing of the hand-held tool. In other embodiments, the center yoke 104 may be omitted (the body has the same thickness except for the convex portion).

2 is a schematic cross-sectional view of the stator according to the embodiment of the application. The stator 100 includes a main body (also called a stator yoke) 101, the outer side of which is symmetrically arranged along the x/y direction center line with convex portions 102, and the inner side of the main body 101 is opposite The horn-shaped salient pole 103 is arranged, and the center yoke 104 is arranged opposite to the inner side of the main body 101. The center line of the center yoke 104 is substantially perpendicular to the center line of the salient pole 103. The salient pole 103 is provided with a pole cut 103a integrally formed therewith. The pole cut 103a is symmetrical along the central axis in the y direction. The thickness of the pole cut 103a gradually decreases from the connection with the salient pole 103 to the end of the pole cut. The angle between the cut ends of the two poles and the center is between 110° and 140°. The outer side of the main body 101 opposite to the salient pole 103 is provided with a tooth width bridge (also called a concave portion) 105, and the y-direction center line of the tooth width bridge 105 coincides with the y-direction center line of the salient pole 103. In other embodiments, the center yoke 104 may be omitted. The stator is an integral stator with a circular cross-sectional profile.

The central yoke 104 protrudes inward, and the ratio (ratio) of the height of the protuberance to the thickness of the stator body in the radial direction is 0.01-0.3. The choke width of the stator is between 3.6mm and 4.2mm. In this embodiment, one side of the convex portion 102 is provided with an inclined surface 102a, and the tangent angle between the inclined surface 102a and the outer surface of the main body 101 with which it contacts is greater than 90°, such as 100, 120°, etc. In this way, after the stator 100 is assembled with the housing (not shown), the convex portion 102 can be used for fixing and preventing the motor from moving (rotating). The radial thickness of the stator body is also called the yoke width.

As a modification of the embodiment in FIG. 2 as shown in FIG. 3, it differs from the method in FIG. 2 in that the inclined surface 202a is arranged on one side of the convex portion 202. The tangent angle between the inclined surface 202a and the outer surface of the main body 201 with which it contacts is less than or equal to 90°, such as 90°, 60°, 45°, 30°. With this design, after the motor and the housing, the protrusion 202 is reliably matched with the housing and serves the purpose of preventing the motor from rotating. In this embodiment, the center yoke can be omitted.

The stator 200 includes a main body (also called a stator yoke) 201, with convex portions 202 arranged symmetrically along the center line of the x/y direction on the outer side, and horn-shaped salient poles 203 arranged opposite to the inner side of the main body 201. The salient poles 203 are integrally formed with it The pole cut 203a. The pole cut 203a is symmetrical along the central axis in the y direction. The thickness h of the pole cut 203a gradually decreases from the connection with the salient pole 203 to the end of the pole cut. The angle between the cut ends of the two poles and the center is between 110° and 140°. The outer side of the body 201 opposite to the salient pole 203 is provided with a tooth width bridge (also called a recess) 205, and the y-direction center line of the tooth width bridge 205 coincides with the y-direction center line of the salient pole 203. The stator 200 has a circular shape as a whole, with an outer diameter D, a body thickness (yoke width) of t1, and a thickness of the convex portion t. The outer diameter of the stator includes the height t2 of the protrusion 203. In an implementation, for the stator body, the thickness of the body except for the protrusions may be t1. The protruding height t2 is between 0.5mm and 3mm, depending on the application.

Next, a schematic diagram of the structure of the motor of the embodiment of the present application will be described with reference to FIGS. 4 and 5. FIG. 5 is a schematic cross-sectional view of BB of the motor of FIG. 4; the motor 10 includes a stator assembly 11 on which a winding 11b is wound, and the inside is configured There is a rotor assembly 14 (refer to FIG. 6), one end of which is connected to the commutator assembly 12, and the other end is connected to the cooling fan 13, which drives the cooling fan 13 to rotate based on the rotation of the rotor. The rotating shaft of the rotor assembly 14 protrudes from the cooling fan 13. The outer diameter of the stator is between 40mm and 57mm (preferably, the outer diameter of the stator is between 40mm and 50mm), and the ratio of the outer diameter of the rotor to the outer diameter of the stator ranges from 0.50 to 0.62 (preferably, the rotor The ratio of the outer diameter D1 (refer to Figure 9) to the stator outer diameter D ranges from 0.50 to 0.60). Preferably, the ratio of the rotor outer diameter D1 to the stator outer diameter D is 0.58 and 0.60. At this time, the efficiency of the motor is high. The ratio of the output power to the volume of the motor is more than 10 (W/cm3). Compared with the current ratio of the output power to the volume of the same type of motor, it is about 8 (or less than 8). The big improvement enhances the output capacity of the motor under the same size. In this embodiment, the ratio of the output power of the motor to its volume is between 8-12 (unit w/cm3). Preferably, the ratio of the output power of the motor to its volume is between 9-11 (unit w/cm3). The stator of the motor adopts the structure of an integral stator, which is pressed and welded by a plurality of laminations to form a hollow integral stator. In the stator of this structure, each lamination in the axial direction is a hollow integral. The rotor assembly and the armature shaft rotated by the rotor assembly are located inside the stator assembly. The hand-held electric tool using the motor preferably has a body approximately cylindrical, extending along the axial direction of the armature shaft, and the axis of the body and the axis of the armature shaft are coaxial.

Define the volume of the motor V=π(D/2) ² *L, where D is the diameter of the stator (including the height of the convex portion), and L is the axial length of the motor, in mm. If converted to the motor volume, V is cm ³ Divide the above calculated value by 1000. L is defined by the length of the stator (the length of the stator/rotor is the same).

The motor of the above-mentioned embodiment has a relatively high rotation speed, such as 40,000 rpm (or higher) when it is running under no load. The power during operation P2=Pl-P, Pl is the input power Pl, and P is the loss. The motor output power P2 has a positive correlation with the diameter D of the motor, the axial length L of the motor, the speed of the motor, and the slot full rate of the motor.

Fig. 6 is a schematic diagram showing the connection between the rotor assembly and the commutator. The rotor assembly 14 includes a rotating shaft 15, one end of which is connected to the commutator assembly 12, and the other end is connected to a cooling fan and a power transmission component (not shown). The rotor assembly is usually a stack of metal laminations piled together in the axial direction and welded together. The main component is iron, so it can also be called an iron core.

Next, in conjunction with FIGS. 7 and 8, the rotor assembly mechanism of the embodiment in FIG. 6 will be further described.

The rotor assembly 14 contains a rotating shaft 15 inside, one end of which is connected to the commutator assembly 12, and the other end is connected to the heat dissipation fan 13. The commutator assembly 12 includes a commutator 12a, is matched with the commutator 12a and connected to an armature shaft, and is electrically connected to the commutator 12a with a brush 12b. In this embodiment, the number of commutators is 24, and the rotor assembly includes 12 slots. In other embodiments, the number of chips and the number of slots can be other values. The rotor assembly 14 has a rotor winding 14a disposed therein. Preferably, the rotor winding 14a partially protrudes from the rotor assembly 14. It is covered with a protective net 14b. The protection net 14b is also called a winding protection wire net, and cotton wax tower wire is preferably used. The rotor assembly 14 also includes a rotor blank 14c inside.

FIG. 8 shows a partial cross-sectional view of the direction B projected to the commutator assembly 12 side in FIG. 7. The inner surface of the slot wedge 17 is provided with insulating paper 16. The inner surface of the slot wedge 17 is coated with an insulating film.

Next, the structure of the rotor assembly according to the embodiment of the present application will be described in conjunction with FIG. 9. The rotor assembly 20 includes a rotor core 22 with teeth 21 uniformly arranged in the circumferential direction. Two adjacent teeth constitute a slot of the rotor, and the rotor is wound inside. For the winding (not shown), one end of the tooth 21 is connected to the rotor core 22, and the other end is connected to the tooth buckle 21a.

As shown in Figure 10, a schematic diagram of the thickness and slot area of the convex part of the stator of the motor, the convex part 62 is arranged on the stator body 61, and the thickness t of the convex part 62 corresponds to the slot area S of the slot 61a corresponding to the winding (the shaded part in the figure , That is, the ratio of the inner side of the convex part, the inner part of the main body, and the area surrounded by the salient pole), t/S is between 8.5 and 11%. The design of the motor increases the effective magnetic flux of the motor and provides its output capacity. The angle θ between the ends of the two poles 63a and the center is between 110° and 140°. Preferably, the included angle θ is between 130°. The cross-section of the stator is roughly circular, and sometimes the thickness can be described as a radial thickness.

The outer diameter of the motor of the above embodiment may be 46mm, 48mm, 50mm, 52mm, 55mm, 57mm (including the height of the protrusion). In one embodiment, the height of the protrusion is 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3.0mm.

The motor of the above embodiment is a brushed motor, which can be used in (hand-held) tools such as angle grinders and swing motors. The diameter of the armature shaft is between 7.5 mm and 9 mm, and the length of the armature shaft is between 50 mm and 180 mm.

The above-mentioned embodiments are only to illustrate the technical ideas and features of the application, and their purpose is to enable people familiar with the technology to understand the content of the application and implement them accordingly, and cannot limit the scope of protection of the application. All equivalent changes or modifications made in accordance with the spirit and essence of this application shall be covered by the protection scope of this application.

Claims

A motor for a hand-held electric tool, characterized in that it comprises:

An integral stator, on its outer side is provided with a plurality of convex portions protruding outward in the radial direction;

A rotor, which is arranged inside the stator;

An armature shaft, which is coaxially connected with the rotor;

A commutator, which is matched and connected with the armature shaft;

A brush, which is electrically connected to the commutator;

The outer diameter of the stator is between 40mm～57mm,

The ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.50 and 0.62.
The motor of claim 1, wherein the outer diameter of the stator is 46mm or 48mm or 50mm or 52mm or 55mm or 57mm, and the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.55 and 0.60 .
The motor according to claim 2, wherein the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.60, and the yoke width of the stator is between 4.4 mm and 5.0 mm.
The motor of claim 1, wherein the ratio of the outer diameter of the rotor to the outer diameter of the stator is between 0.58 and 0.60, the yoke width of the stator is between 3.8 mm and 5.0 mm, and the output of the motor The ratio of power to volume is between 8-12.
The motor according to claim 1, wherein the integral stator has four convex portions uniformly arranged in the outer circumferential direction, and the convex portions are axially symmetric in the first direction or the second direction.
The motor according to claim 1, wherein the convex part is integrally formed with the stator body, and the thickness of the convex part is between 3.8 mm and 6.0 mm.
The motor according to claim 1, wherein the length of the stator along the axis of the armature shaft is between 40 mm and 60 mm.
The motor of claim 1, further comprising a heat dissipation fan, which is coaxially connected with the rotating shaft of the rotor through a connector, and drives the heat dissipation fan to rotate based on the rotation of the rotation shaft; the diameter of the heat dissipation fan is larger than For the outer diameter of the rotor, the ratio of the diameter of the heat dissipation fan to the outer diameter of the rotor is between 1.5-3.
8. The motor of claim 8, wherein the ratio of the diameter of the cooling fan to the outer diameter of the stator is between 1.1 and 1.8.
5. The motor of claim 1, wherein the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.58, and the yoke width of the stator is between 3.8 mm and 5.0 mm.
The motor according to claim 1, characterized in that a pair of tooth width bridges are arranged, which are arranged oppositely on the outer side of the integral stator, and the stator In the axial direction, the surfaces on which the tooth width bridge sides are respectively arranged are parallel.
The motor according to claim 1, wherein the ratio of the height of the protrusion to the thickness of the protrusion is between 0.1 and 0.5.