CN210724523U

CN210724523U - Motor for electric tool with multiple yoke widths

Info

Publication number: CN210724523U
Application number: CN201921216099.3U
Authority: CN
Inventors: 吴晓婷
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-31
Filing date: 2019-07-31
Publication date: 2020-06-09
Anticipated expiration: 2029-07-31

Abstract

The utility model provides a wide motor for electric tool of multistage yoke. The motor comprises an integral stator, a stator core and a stator core, wherein the outer side of the integral stator is provided with a plurality of convex parts protruding outwards along the radial direction of the integral stator, and the circumferential inner side of each convex part is provided with a concave part for accommodating a winding; a rotor disposed inside the stator; a commutator assembly coaxially connected to the rotor; the commutator component comprises a connecting armature shaft coaxial with the rotor, a commutator matched and connected with the armature shaft and an electric brush electrically connected with the commutator; the outer diameter of the stator is 40 mm-57 mm, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.50-0.62, and the ratio of the width of the yoke of the stator to the thickness of the convex part is 0.75-1.0. Compared with the stator with the same size, the motor adopting the embodiment of the application has the advantages that the slot fullness rate of the motor is improved, and the output capacity under the same condition is improved.

Description

Motor for electric tool with multiple yoke widths

Technical Field

The utility model relates to a motor specifically relates to a wide motor for electric tool of multistage yoke.

Background

Hand-held power tools, such as angle grinders and swing machines, require a user to operate a hand-held tool to perform cutting, drilling, grinding, and other operations on a workpiece. In the prior art, a split stator motor is adopted to replace a conventional integral motor. The split type motor is characterized in that a stator of the split type motor is divided into a plurality of blocks before winding, the amount of winding can be increased by each block of independent winding, and the blocks are spliced or welded into a whole after the winding is finished. Under the conventional process, the split stator can wind more coils than the integral stator, so that the power of the motor can be improved. However, the manufacturing and assembling process of the split stator is more complicated than that of the integral stator, and the manufacturing cost is much higher, so that the split stator is limited to be widely used in the handheld electric tool products.

SUMMERY OF THE UTILITY MODEL

Based on the above problem, the utility model provides a motor for electric tool, it has with low costs, power density is high. A brushed electric motor having an integral stator.

Therefore, the utility model adopts the following technical scheme:

a multi-step yoke width motor for electric tool is characterized by comprising an integral stator, a plurality of convex parts which are arranged on the outer side of the integral stator and protrude outwards along the radial direction of the integral stator, and concave parts which are arranged on the inner side of the circumferential direction of the convex parts and are used for accommodating winding wires;

a rotor disposed inside the stator;

a commutator assembly coaxially connected to the rotor; the commutator component comprises a connecting armature shaft coaxial with the rotor, a commutator matched and connected with the armature shaft and an electric brush electrically connected with the commutator;

the outer diameter of the stator is 40 mm-57 mm, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.50-0.62,

the ratio of the yoke width of the stator to the thickness of the convex part is 0.75-1.0. By adopting the design, the slot filling rate and the output capacity of the motor are improved.

Preferably, the stator further includes a pair of flared salient poles disposed to face each other and disposed inside the stator, a pair of center yokes disposed to face each other and disposed inside the stator, a center line of the pair of center yokes being perpendicular to a center line of the pair of salient poles, and a ratio of a yoke width of the center yoke to a thickness of the convex portion being 0.75 to 1.0.

Preferably, 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 0.55-0.60.

Preferably, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.60, and the width of the central yoke of the stator is 3.6mm to 4.2 mm.

Preferably, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.58-0.60, the thickness of the convex part is 4.8mm, and the ratio of the output power of the motor to the volume of the motor is 9-11 w/cm 3.

Preferably, the convex part is integrally formed with the stator, and the thickness of the convex part is 3.8mm to 5.0 mm.

Preferably, the length of the stator in the axial direction of the armature shaft is 40mm to 60 mm.

Preferably, the diameter of the armature shaft is between 6mm and 8 mm.

Preferably, the motor further comprises a heat radiation fan, the heat radiation fan is coaxially connected with the rotating shaft of the rotor through a connecting piece, and the heat radiation fan is driven to rotate based on the rotation of the rotor; the diameter of the heat radiation fan is larger than the outer diameter of the rotor, and the ratio of the diameter of the heat radiation fan to the outer diameter of the rotor is 1.5-3.

Preferably, the ratio of the thickness of the convex part to the area of the groove is 8.5-11%.

For the scheme among the prior art, the utility model discloses an advantage:

compared with the design that the stator of the existing motor adopts the equal yoke width, the motor of the embodiment of the application adopts the design of multiple sections of yoke widths, so that the slot filling rate of the motor is improved, the power density of the motor is improved, and the like.

Drawings

The invention will be further described with reference to the following drawings and examples:

fig. 1 is a schematic structural diagram of a motor according to an embodiment of the present invention;

fig. 2 is a schematic view of a stator structure of a motor according to an embodiment of the present invention;

fig. 3 is a schematic cross-sectional view of a stator according to an embodiment of the present invention;

FIG. 4 is a schematic view of a rotor according to an embodiment of the present invention

Fig. 5 is a schematic cross-sectional view of a stator according to another embodiment of the present invention;

fig. 6 is a schematic cross-sectional view of a rotor assembly according to an embodiment of the present invention;

fig. 7 is a schematic cross-sectional view of an electric machine according to an embodiment of the present invention;

fig. 8 is a schematic diagram of the areas of the convex portions and the grooves of the motor according to the embodiment of the present invention.

Detailed Description

The above-described scheme is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes and are not intended to limit the scope of the present invention. The conditions used in the examples may be further adjusted according to the conditions of the particular manufacturer, and the conditions not specified are generally the conditions in routine experiments.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only. In the present embodiment, the outer diameter of the stator includes a height at which the convex portion protrudes.

Example (b):

the electric machine according to an embodiment of the present invention will be described with reference to fig. 1 to 8. The drawings include schematic diagrams, and the scale and the vertical-to-horizontal ratio of each component may be different from those of the actual components.

As shown in fig. 1, a motor 50 includes a stator 51, a winding 52 (also called an enameled wire/copper wire) is disposed in the stator, a rotor assembly (not shown) is disposed in the winding, one end of the winding is connected to a commutator assembly 53, and the other end of the winding is connected to a heat dissipation fan 55, which is driven by the rotation of the rotor assembly. The output 55 of the motor is used to connect to a transmission member (not shown). The stator 51 is provided with tooth-width bridges 56 (also referred to as recesses) on opposite sides thereof. Preferably, the surfaces 56a of the two sides of the tooth width bridge 56 are parallel. In the present embodiment, the motor is a brush motor.

Referring to fig. 2 and 3, a stator 10 according to an embodiment of the present invention is described, which includes a main body (also referred to as a stator yoke) 11, a convex portion 12 disposed outside the main body, a concave portion 12b disposed inside the convex portion 12 and having a similar protruding profile to the convex portion, a trumpet-shaped salient pole 13 disposed inside the main body 11, and a center yoke 14 disposed inside the main body 11 and opposing the center yoke 14, wherein a center line of the center yoke 14 is substantially perpendicular to a center line of the salient pole 13. Preferably, the body is integrally formed with a boss, sometimes referred to as a bottom yoke, having a yoke width that is greater than or equal to the width of the boss at a location other than the bottom yoke. In the present embodiment, by disposing the concave portion inside the convex portion 12 of the stator in the same size, the wire harness of the stator inner winding can be increased, and the slot filling factor of the motor can be increased. Compared with the design that the stator of the existing motor mostly adopts the equal yoke width, the motor of the embodiment of the application adopts the design of multi-section yoke width (the thickness of the convex part is different from that of the non-convex part, and preferably, the thickness of the convex part is more than or equal to that of the non-convex part), so that the slot filling rate of the motor is improved, the power density of the motor is improved, and the like. The multi-segment yoke width is at least 2 segments of yoke width. The salient pole 13 includes a pole piece 13a integrally formed therewith, and the pole piece 103a is symmetrical along a central axis in the y-direction. The thickness of the pole-cut 13a is gradually reduced from the connection with the salient pole 13 to the end of the pole-cut. The included angle between the end portions of the two pole-cutting and the center is 110-140 degrees (such as 110 degrees, 120 degrees, 130 degrees and 140 degrees). Wide tooth bridges (also referred to as recesses) 15 are disposed on the outer side of the body 11 facing the salient poles 13, and the y-center lines of the wide tooth bridges 15 overlap the y-center lines of the salient poles 13. Preferably, the projections 12 are symmetrical about the x/y centerline. The convex portion 12 is sometimes also called a bottom portion. The height h of the inward protrusion of the center yoke 14 is 0.01-0.3 of the thickness ratio of the body to the height h. The yoke width of the stator is 3.6mm to 5.0 mm. Preferably, the thickness is between 4.2mm and 4.8 mm.

In the above embodiment, the ratio of the yoke width of the center yoke (the yoke width 1 at the narrowest part of the center yoke) to the thickness of the convex portion 12 (also referred to as the yoke width 2) is 0.75 to 1.0. If the yoke width of the center yoke is greater than the thickness of the protrusion 12, the yoke width at the narrowest point of the stator body is selected (denoted as yoke width 1). The ratio of the rotor outer diameter to the stator outer diameter is 0.55-0.60. As shown in the following table, the ratio of the output power to the volume of the motor (W/cm3) was determined for different ratios of yoke width 1/yoke width 2

TABLE 1

In other embodiments, the center yoke may be omitted, and the ratio of the yoke width at the narrowest portion of the stator body (denoted as yoke width 1) to the thickness at the salient 12 (also referred to as yoke width 2) is selected to be 0.75-1.0, and any of the output power to volume ratios listed in the above tables may be applied. (typically, the thickness is narrowest at the center yoke when the stator is designed).

As shown in Table 2 below, the ratio of the rotor outer diameter to the stator outer diameter is different, the ratio of the output power to the volume of the motor (W/cm3) is different for different yoke widths 2 widths

TABLE 2

As can be seen from table 1, the effect of the yoke width on the motor performance is shown, and in the case where the yoke 1 is not changed, the width of the bottom yoke width (yoke 2) is increased, and the motor power density is greatly increased. However, the yoke 1 is affected by the structure and the slot fill factor (the ratio of the winding copper wire to the slot area), and when the width of the yoke 1 reaches a certain value, the power is not increased. There is an optimum ratio of yoke 1 to yoke 2 to maximize the motor power density. In table 2, the yoke 2 is the most dense place of the motor magnetic flux density, and is easily saturated in magnetic flux density, so that the motor power cannot be increased, and the temperature is increased. The width of the yoke 2 is increased. The wide band degree of yoke 2 influences stator external diameter size (under the limited condition in space, the external diameter size of general yoke 2 matches with its support piece internal diameter, is called profile modeling design for yoke width is equitable maximize, increases the magnetic flux, increases output power), and the performance contrast is paird through best inside and outside than the ratio, and the width of yoke 2 obtains the best performance parameter. The power density reaches more than 10W/cm 3.

In the present embodiment, an inclined surface 12a is disposed on one side of the convex portion 12, and an angle formed by the inclined surface 12a and a tangent line of the outer surface of the main body 101 with which the inclined surface is in contact is greater than 90 °, for example, 100 ° or 120 °. Thus, the stator 100 is assembled with a housing (not shown), and the protrusion 12 can fix and prevent the motor from moving (rotating). The ratio of the circumferential length of the center yoke 14 to the thickness of the body 11 at the position thereof is 0.5-2. Preferably, the circumferential length is slightly equal to the thickness of the body at the position of the circumferential length. The horn-shaped salient pole 13 has an axial length equal to that of the stator body, and forms a slot with the side wall of the stator, and a winding (also called copper wire/enameled wire, not shown) wound according to a certain rule is wound inside the slot. The outer profile of the unitary stator may be circular, oval, oblong, or other shape suitable for receipt in the housing of a hand held tool. The ratio of the protruding height of the convex part to the thickness of the convex part is 1.01-1.5.

As shown in fig. 5, a modification of the embodiment of fig. 3 is different from the embodiment of fig. 5 in that an inclined surface 32a is provided on one side of the projection 32, and an angle between the inclined surface 32a and a tangent of the outer surface of the main body 31 in contact therewith is 90 °, such as 90 °, 60 °, 45 °, and 30 °. This arrangement allows the projection 22 to fit securely with the housing and serves the purpose of preventing rotation of the electronics.

Fig. 7 is a schematic cross-sectional view of a stator of an electric motor according to an embodiment of the present application; the motor stator 60 includes a body 61, a projection 62 disposed in a circumferential direction of the body, a horn-shaped salient pole 63 disposed in an inner side of the body, and the salient pole 63 including a pole piece 63a integrally formed therewith. In this embodiment, the concave portion is disposed inside the convex portion 62, and this design increases the number of windings on the salient pole 63, thereby increasing the slot fill factor of the motor. In this embodiment, the yoke using the convex portion (the convex portion may be also referred to as a bottom yoke) is designed to be wider than other portions (as compared with a conventional motor in which the yoke is designed to be as wide as the stator), thereby increasing the magnetic flux, reducing flux saturation, and increasing the motor output. In addition, because the area of the winding slot is enlarged, the wire diameter of the winding can be thickened, thus reducing copper loss and improving the power of the motor. As shown in FIG. 8, the ratio of the thickness t of the protrusion 62 to the slot area S (see the shaded area, i.e., the area of the protrusion inside, the body inside, and the salient pole enclosure) of the motor electronics is 8.5-11%. The effective magnetic flux of the motor is increased by the design of the motor, and the output capacity of the motor is improved. The included angle theta between the tail end and the center of the bipolar cutting 63a is between 110 and 140 degrees. Preferably, the included angle θ is 130 °. As shown in Table 3, when the stator outer diameter is 52mm (including the height of the projection), and the thickness of the projection (the width of the yoke) is different, the ratio of the power to the volume of the motor (W/cm3),

TABLE 3

In this embodiment, the thickness of the convex portion is selected to be 4.6 mm.

Next, referring to fig. 4, a description will be given of a rotor assembly structure according to an embodiment of the present invention, a rotor assembly 20 includes a rotor core 22, in which teeth 21 are uniformly arranged in a circumferential direction, adjacent two teeth form a rotor slot, in which a rotor winding (not shown) is wound, and one end of each tooth 21 is connected to the rotor core 22, and the other end is connected to a tooth catch 21 a.

The rotating shaft of the rotor assembly protrudes out of the cooling fan. The outer diameter of the stator is 40-50 mm, and the ratio of the outer diameter of the rotor to the outer diameter of the stator ranges from 0.50 to 0.60. Preferably, the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.58 to 0.60. At the moment, the efficiency of the motor is high, the ratio of the output power of the motor to the volume is close to more than 10W/cm3, and compared with the current ratio of the output power of the same type of motor to the volume of about 8 (or less than 8), the efficiency of the motor is greatly improved, and the output capacity of the motor with the same size is enhanced. In this embodiment, the stator of the motor is a monolithic stator structure formed by press-welding a plurality of laminations to form a hollow monolithic stator, and each lamination in the axial direction of the stator is a hollow monolithic body. The rotor assembly and the armature shaft driven by the rotor assembly to rotate are located on the inner side of the stator assembly. The hand-held electric tool using the motor preferably has a body which is approximately cylindrical and extends in the axial direction of the armature shaft, and the axis of the body is coaxial with the axis of the armature shaft.

Volume of motor defined V ═ pi (D/2)²Where D is the stator diameter (including the height of the projection), L is the axial length of the motor in mm, and when converted into the motor volume V, it is cm³The above calculated value is then divided by 1000. L is defined in terms of stator length (the stator/rotor lengths are the same).

The motor of the above embodiment, which operates when empty, has a high rotation speed, e.g., 40000rpm (e.g., 38000rpm, 39000rpm, or higher). During operation, power P2 is equal to Pl-P, where 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 rotational speed of the motor, and the slot fill rate of the motor.

As shown in fig. 6, which is a schematic structural diagram of the connection between the rotor (rotor assembly) and the commutator assembly, the rotor assembly 41 includes a rotating shaft (not shown), one end of which is connected to the commutator assembly 44, the other end of which is connected to the heat dissipation fan 43 and is connected to the power transmission member (not shown) through the output shaft 44. The commutator assembly 42 includes a commutator 42a, a armature shaft coupled to the commutator 42a, and a brush 42b electrically connected to the commutator 42 a. In this embodiment, the number of commutator segments is 24, and the rotor assembly includes 12 slots. In other embodiments, the number of slices and the number of slots may have other values. The rotor assembly 41 has rotor windings 41a disposed therein. Preferably the rotor winding 41a partially protrudes from the rotor assembly 41. Which is covered with a protective netting 41 b. The protection net 41b is also called a winding protection net. The rotor assembly also includes a rotor blank 41c (shaft) located inside it. The rotor assembly is typically a stack of laminations formed by axially stacking and welding together a suitable number of metallic laminations, the main constituent of which is iron, and which may also be referred to as a core.

The outer diameter of the motor of the above embodiment may be 46mm, 48mm, 50mm, 52mm, 55mm, 57 mm.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. A multi-step yoke width motor for electric tool, comprising

A one-piece stator having a plurality of protrusions protruding radially outward from an outer side thereof, and a recess for accommodating a winding wire disposed on a circumferential inner side of the protrusions;

a rotor disposed inside the stator;

the ratio of the yoke width of the stator to the thickness of the convex part is 0.75-1.0.

2. The electrical machine of claim 1,

the stator further comprises a pair of horn-shaped salient poles which are arranged oppositely and are respectively arranged at the inner side of the stator, a pair of central yokes which are arranged oppositely and are respectively arranged at the inner side of the stator, the center line of the central yokes is vertical to the center line of the salient poles, and the ratio of the yoke width of the central yokes to the thickness of the convex parts is 0.75-1.0.

3. The motor of claim 1, wherein the stator has an outer diameter of 46mm or 48mm or 50mm or 52mm or 55mm or 57mm, and the ratio of the rotor outer diameter to the stator outer diameter is between 0.55 and 0.60.

4. The motor of claim 3 wherein the ratio of the rotor outer diameter to the stator outer diameter is 0.60 and the stator center yoke width is between 3.6mm and 4.2 mm.

5. The motor of claim 3, wherein the ratio of the outer diameter of the rotor to the outer diameter of the stator is 0.58-0.60, the thickness of the protrusions is 4.8mm, and the ratio of the output power of the motor to the volume thereof is 9-11 w/cm 3.

6. The motor of claim 1, wherein the boss is integrally formed with the stator, and the thickness at the boss is between 3.8mm and 5.0 mm.

7. The motor according to claim 1, wherein a length of the stator in an axial direction of the armature shaft is 40mm to 60 mm.

8. An electrical machine according to claim 1, wherein the diameter of the armature shaft is between 6mm and 8 mm.

9. The motor according to claim 1, further comprising a heat radiation fan coaxially connected to a rotation shaft of the rotor through a connection member, the heat radiation fan being rotated based on rotation of the rotor; the diameter of the heat radiation fan is larger than the outer diameter of the rotor, and the ratio of the diameter of the heat radiation fan to the outer diameter of the rotor is 1.5-3.

10. The motor of claim 1, wherein the ratio of the thickness of the protrusions to the area of the slots is between 8.5 and 11%.