Power tool, motor, and motor rotor assembly

Abstract

Disclosed are a power tool, an electric motor, and a rotor assembly for the motor. The rotor assembly includes a rotating shaft (4), a rotor body (1) fixed on the rotating shaft (4), a restricting member (2), and a cooling fan (3), the restricting member (2) and the cooling fan (3) being respectively disposed at two axial ends of the rotor body (1), the rotor body (1) including a rotor core (11) and a magnet (12) fixed within the rotor core (11), the restricting member (2) and the cooling fan (3) jointly defining the axial and radial displacements of the magnet (12) of the rotor body (1). Based on this rotor assembly, the magnet (12) is fixedly attached within the rotor core (11) using only mechanical assembly methods, thereby reducing the number of elements of the rotor assembly, facilitating assembly, and effectively reducing manufacturing costs.

Description

[Technical Field]

[0001] The present invention relates to the field of electrical engineering, and more particularly to a rotor assembly, a motor having a rotor assembly, and a power tool having a motor. [Background technology]

[0002] Typically, the rotor of an internal rotor motor includes a rotor core and a ring magnet sleeved around the rotor core, which is fixed to the rotor core by adhesive bonding. The ring magnet is axially positioned by a holder fixed to the rotating shaft. However, some applications, such as power tools, require motors to have relatively high rotation speeds. In the prior art, to prevent the ring magnet from cracking or flying off under high-speed rotor rotation, an upper sleeve and a lower sleeve are usually sleeved around the ring magnet, which inevitably increases magnetic resistance, increases the air gap between the rotor and the stator, and increases the material cost and assembly process of the motor. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rotor assembly, a motor having a rotor assembly, and a power tool having a motor that can solve the above problems. [Means for solving the problem]

[0004] Therefore, the present invention provides a rotor assembly including a rotating shaft, a rotor body fixed to the rotating shaft, a restricting member, and a cooling fan, wherein the restricting member and the cooling fan are respectively arranged at both axial ends of the rotor body, the rotor body includes a rotor core and a magnet fixed within the rotor core, and the restricting member and the cooling fan collectively restrict the axial and radial displacements of the magnet.

[0005] In some embodiments, a cooling fan abuts the axial end of the magnet.

[0006] In some embodiments, the cooling fan includes a protrusion that extends toward the rotor body, the protrusion abutting the axial end of the magnet.

[0007] In some embodiments, the rotor core defines a mounting hole for mounting the magnet and a positioning hole located on a side of the mounting hole and communicating with the mounting hole, and the protrusion is at least partially inserted into the positioning hole and abuts against the magnet.

[0008] In some embodiments, the protrusion includes a stop that abuts an end face of the axial end of the magnet to prevent the magnet from moving towards the cooling fan.

[0009] In some embodiments, the radial dimension of one end of the protrusion closer to the cooling fan is greater than the dimension of the free end of the protrusion so as to form a stop, the stop being a ramp or a step.

[0010] In some embodiments, the cooling fan further includes a base, the protrusions being formed on the base and fully inserted into the rotor core, with the base directly abutting the axial ends of the magnets.

[0011] In some embodiments, the locating hole is located in the center of the side of the mounting hole facing the rotating shaft or away from the rotating shaft.

[0012] In some embodiments, the cooling fan includes a flange formed integrally with the cooling fan and extending toward the rotor body, the flange being deformed by pressing of the rotor core during installation of the rotor assembly and at least partially abutting the axial end of the magnet.

[0013] In some embodiments, the rotor core defines mounting holes for mounting the magnets, and at least a portion of the flange is embedded in the bottom of the mounting holes in the rotor core after being deformed and abutting the magnets.

[0014] In some embodiments, the restricting member abuts the other axial end of the magnet directly or via an elastic washer.

[0015] In some embodiments, the rotor core defines a mounting hole for mounting the magnet and a positioning hole located on a side of the mounting hole and communicating with the mounting hole, and the restricting member includes a protrusion extending toward the rotor body, the protrusion being at least partially inserted into the positioning hole and abutting the magnet.

[0016] The present invention also provides a motor including a stator and a rotor assembly as described above, the rotor assembly being rotatably disposed within the stator.

[0017] The present invention also provides a power tool including the motor described above.

[0018] In the rotor assembly provided by the embodiments of the present invention, the magnets can be installed and fixed in the rotor core through mechanical assembly only, which reduces the number of parts in the rotor assembly, makes assembly convenient, and effectively reduces manufacturing costs. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is an assembled perspective view of a rotor assembly according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the rotor assembly of FIG. 1. [Figure 3a] FIG. 2 is a bottom view of the rotor assembly of FIG. 1. [Figure 3b] 3b is a cross-sectional view of the rotor assembly of FIG. 3a taken along section line AA. [Figure 4a] FIG. 2 is a perspective view of a rotor core of the rotor assembly of FIG. 1. [Figure 4b] FIG. 4b is an end view of the rotor core of FIG. 4a. [Figure 5] 2 is a diagram showing a schematic positional relationship between a cooling fan and a magnet of the rotor assembly of FIG. 1. FIG. [Figure 6]FIG. 10 is an exploded perspective view of a rotor assembly according to another embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view of the rotor assembly of FIG. 6 in an assembled state. [Figure 8] FIG. 10 is an exploded perspective view of a rotor assembly according to yet another embodiment of the present invention. [Figure 9] 1 illustrates a motor according to an embodiment of the present invention. [Figure 10] 1 illustrates a power tool according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to make the technical solutions and beneficial effects of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It can be understood that the drawings are provided for reference and explanation only and are not used to limit the present invention. The dimensions shown in the drawings are for the convenience of clarity of description only and do not limit the proportional relationship.

[0021] 1 is an assembled perspective view of a rotor assembly 100 according to a first embodiment of the present invention. The rotor assembly 100 includes a rotating shaft 4, a rotor body 1 fixed to the rotating shaft 4, a restricting member 2, and a cooling fan 3. The restricting member 2 and the cooling fan 3 are disposed at both axial ends of the rotor body 1, respectively.

[0022] 2, 3a, and 3b, the rotor body 1 includes a rotor core 11 and a plurality of magnets 12 axially inserted into the rotor core 11. The magnets 12 are arranged at circumferential intervals around the rotating shaft 4 within the rotor core 11. In this embodiment, the length of the magnet 12 in the axial direction of the rotating shaft 4 is approximately equal to the axial length of the rotor core 11, i.e., the two ends of the magnet 12 in the axial direction are substantially flush with the two axial ends of the rotor core 11 in the axial direction. Both ends of the magnet 12 in the axial direction of the rotating shaft 4 abut against the restricting member 2 and the cooling fan 3, respectively, to prevent the magnet 12 from moving relative to the rotor core 11. In other embodiments, the length of the magnet 12 may be slightly shorter than the axial length of the rotor core 11.

[0023] 4a and 4b, the rotor core 11 is substantially cylindrical and has mounting holes 111 for mounting the magnets 12. The mounting holes 111 extend axially and penetrate the rotor core 11. The mounting holes 111 are arranged circumferentially around the rotating shaft 4. In this embodiment, the mounting holes 111 have a substantially rectangular cross section, and protrusions are provided at both ends to limit circumferential movement of the magnets. The rotor core 11 further defines positioning holes 112 at the center of the radially inner side of each mounting hole 111, and the positioning holes 112 communicate with the corresponding mounting holes 111. In this embodiment, the positioning holes 112 extend perpendicular to the radially inner side of the corresponding mounting holes 111 and also penetrate the rotor core 11 in the axial direction. In other embodiments, the axial length of the positioning holes 112 can be shorter than the axial length of the rotor core 11. That is, the positioning holes 112 extend axially a certain distance from one end face of the rotor core 11 and do not penetrate the other end face of the iron core 11. The positioning holes 112 are preferably disposed at the centers radially inside the mounting holes 111. The magnets 12 are inserted into the mounting holes 111. In this embodiment, the rotor body 1 includes four magnets 12, each in the shape of a rectangular plate. Correspondingly, there are four mounting holes 111, which are equally spaced around the circumference of the rotor core 11 and arranged in a square. It is understood that the specific numbers of the mounting holes 111 and the positioning holes 112, and their specific positional relationship, can be set according to actual needs.

[0024] The cooling fan 3 includes a base 31 and a plurality of blades 33 on the outer periphery of the base. The base 31 has a substantially circular shape and is disposed facing the rotor body 1. The side of the base 31 facing the rotor body 1 has a plurality of protrusions 32 extending toward the rotor body 1. The protrusions 32 are at least partially inserted into positioning holes 112 in the rotor core 11 and can abut against the magnets 12 installed in the corresponding mounting holes 111. Referring also to FIG. 5 , the radially outer side of the end of each protrusion 32 close to the base 31 has an inclined surface 321 that extends outward so that the radial dimension of the end of the protrusion 32 close to the base 31 is larger than the dimension of the free end of the protrusion 32. The inclined surface 321 abuts against the end of the magnet 12 installed in the mounting hole 111, thereby limiting axial and radial movement of the magnet 12 toward the cooling fan 3. The arrangement of the protrusions 32 and their angled surfaces 321 allows the corresponding magnets 12 to be press-fit into the mounting holes 111 of the rotor core 11, and the arrangement of the angled surfaces 321 reduces machining precision requirements by allowing for certain assembly deviations. In this embodiment, the protrusions 32 are preferably made of plastic and are injection molded integrally with the base 31 and blades 33.

[0025] In this embodiment, the protrusions 32 have inclined surfaces 321 for restricting the magnets 12 in the axial and radial directions. In other embodiments, the inclined surfaces 321 can be replaced with steps that abut against the ends of the magnets 12, thereby restricting the axial movement of the magnets 12 in the direction toward the cooling fan 3. The inclined surfaces 321 or steps form stops for the protrusions 32 and function as stops for the axial ends of the magnets.

[0026] In other embodiments, the positioning holes 112 may be located radially outward of the mounting holes 111, in which case the inside of the protrusions contact the magnets, and corresponding inclined surfaces may be provided on the radially inner side of the ends of the protrusions closer to the base 31 to limit axial and radial movement of the magnets 12 toward the cooling fan 3. In other embodiments, inclined surfaces are provided on the radially inner and outer side of the ends of each protrusion closer to the base 31 to limit axial and radial movement of the magnets 12 toward the cooling fan 3. It may be understood that the arrangement of the protrusions and their inclined surfaces may be designed according to actual requirements.

[0027] The limiting member 2 is fixed to the rotating shaft 4 located at the other end of the rotor body 1. The surface of the limiting member 2 facing the rotor body 1 is a limiting surface 21, which abuts against the other axial end of the rotor body 1 and the other end of the magnet 12, thereby limiting axial movement of the magnet toward the limiting member 2. In this way, the limiting member 2 cooperates with the cooling fan 3 to limit the axial displacement of the magnet 12. In this embodiment, the cross section of the limiting member 2 is circular. The radius of the limiting surface 21 of the limiting member 2 is preferably greater than the shortest distance between the magnet 12 and the axis of the rotating shaft 4 and equal to or less than the diameter of the rotor core 11. In another embodiment, the limiting member 2 may have a protrusion that engages with a positioning hole, and the protrusion at one end of the limiting member 2 may limit the radial and / or axial movement of the magnet 12.

[0028] In the present invention, the arrangement of the restricting member 2 and the protrusions 32 of the cooling fan 3 described above allows the magnets 12 installed in the mounting holes 111 of the rotor core 11 to be securely fixed in the mounting holes 111 using only mechanical fixing means. The magnets 12 can be assembled into the rotor core 11 without using adhesive, and the magnets 12 can be held in the appropriate position, reducing the number of parts in the rotor assembly 100, simplifying the assembly process, and effectively reducing costs.

[0029] 6 and 7 show a rotor assembly 100 according to a second embodiment of the present invention. The main difference between this embodiment and the previously described embodiments is that a washer 5 is disposed between the rotor body 1 and the restricting member 2. The shape of the washer 5 preferably matches the restricting surface 21 of the restricting member 2, so the above description of the restricting surface 21 also applies to the washer 5. The washer 5 is preferably formed from an elastic material, such as rubber, to provide a limited elastic preloading force to the magnets 12 disposed within the rotor core 11.

[0030] Furthermore, in this embodiment, the protrusions 32 of the cooling fan 3 extend vertically from the base 31, i.e., the protrusions 32 do not have an inclined surface. In this embodiment, when the protrusions 32 are fully inserted into the positioning holes 112, both ends of the rotor core 11 in the axial direction of the rotating shaft 4 abut against the surfaces of the washer 5 and the base 31, respectively. Both ends of the magnets 12 installed in the rotor core 11 in the axial direction of the rotating shaft 4 are restricted by the restricting member 2 and the cooling fan 3, respectively, preventing axial movement of the magnets 12 relative to the rotor core 11. The elastic preload force of the washer 5 presses the magnets 12 assembled in the rotor core 11 toward the cooling fan 3, thereby pressing the magnets 12 tightly against the base 31 of the cooling fan 3. Therefore, the design of the washer 5 allows for a certain degree of assembly deviation, thereby reducing the machining precision requirements.

[0031] FIG. 8 shows a cooling fan 3' of a rotor assembly 100' according to a third embodiment of the present invention. Comparing the rotor assembly 100' of the third embodiment with the rotor assembly 100 of the first embodiment, the main differences are that the protrusions 32' of the base 31' of the cooling fan 3' may or may not have inclined surfaces that abut the magnets 12, and that the side of the base 31' facing the rotor body 1 further includes a flange 34' that is integrally injection molded with the base 31' and surrounds the multiple protrusions 32'. The axial height of the flange 34' is smaller than the height of the protrusions 32'. When installing the rotor assembly 100', the rotor core 11 and the magnets 12 inserted into the mounting holes 111 are pressed toward the cooling fan 3' using an air press or hydraulic press, and the protrusions 32' are at least partially inserted into the rotor core 11. As the rotor core 11 presses against the flange 34', the flange 34' is crushed and deformed, and becomes partially embedded in the bottom of each mounting hole 111 of the rotor core 11. Therefore, the radial movement of the magnets 12 housed in the rotor core 11 can be restricted by the protrusions 32', and the axial movement can be restricted by at least the deformed portions of the flange 34' fitted into the mounting holes 111 of the rotor core 11 and the restricting member 2. This allows the magnets 12 to be fixed more effectively.

[0032] In this embodiment, the flange 34' is annular. In other embodiments, the flange 34' can be designed with other shapes or formed with multiple discontinuous flanges depending on the arrangement of the mounting holes 111, and the height and width of the flange can be designed differently depending on requirements.

[0033] 9 shows a motor 300 having a rotor assembly of the present invention, which includes a stator 200 and a rotor assembly 100 disposed inside the stator 200 and rotatable relative to the stator 200. The motor 300 of the present invention is suitable for, but not limited to, power tools.

[0034] 10 shows a power tool 400 having the motor 300 of the present invention, which may be, for example, a power drill including a drill body 401, a motor 300 attached to the drill body 401, and a drill bit 402 driven by the motor 300. The motor 300 of the present invention may also be applied to other power tools.

[0035] The above are merely preferred specific implementations of the present invention. The protection scope of the present invention is not limited to the above-mentioned embodiments. It is obvious that those skilled in the art can acquire techniques within the technical scope disclosed in the present invention. Simple modifications or equivalent replacements of the present solutions fall within the protection scope of the present invention. [Explanation of symbols]

[0036] 1 Rotor body 100 rotor assembly 2. Restriction member 3 Cooling Fan 4 rotating shaft 11 Rotor core 12 Magnet 21 Restrictive Surface

Claims

1. A rotor assembly including a rotating shaft, a rotor body fixed to the rotating shaft, a restricting member, and a cooling fan, the restricting member and the cooling fan being respectively disposed at both axial ends of the rotor body, the rotor body including a rotor core and a magnet fixed within the rotor core, the restricting member and the cooling fan collectively restricting axial and radial displacements of the magnet, the rotor core defines mounting holes for mounting the magnets and positioning holes communicating with the mounting holes, each of the positioning holes being disposed at the center of a corresponding one of the mounting holes on a side facing the rotation shaft or a side away from the rotation shaft; The length of each of the positioning holes is shorter than the length of the corresponding mounting hole in the length direction of the corresponding mounting hole; the cooling fan includes a protrusion formed integrally with the cooling fan and extending toward the rotor body, each of the magnets includes a first axial end and a second axial end opposite the first axial end, and the protrusion is at least partially inserted into the positioning hole and abuts against the first axial end of the magnet; A rotor assembly comprising:

2. each protrusion including a stop that abuts the first axial end of the corresponding magnet to prevent the magnet from moving toward the cooling fan; The rotor assembly of claim 1 .

3. a radial dimension of one end of each protrusion close to the cooling fan is greater than a radial dimension of a free end of the protrusion so as to form the stop, the stop being an inclined surface or a step; The rotor assembly of claim 2 .

4. the cooling fan further includes a base, the protrusion is integrally formed on the base and is fully inserted into the rotor core, and the base directly abuts against the first axial end of the magnet. The rotor assembly of claim 1 .

5. the cooling fan includes a flange formed integrally with the cooling fan and extending toward the rotor body, the flange being deformed by pressing of the rotor core during installation of the rotor assembly and at least partially abutting the first axial end of the magnet; The rotor assembly of claim 1 .

6. At least a portion of the flange is deformed to come into contact with the magnet and then embedded in a bottom portion of the mounting hole of the rotor core. The rotor assembly of claim 5 .

7. the limiting member abuts against the second axial end of the magnet directly or via an elastic washer; The rotor assembly of claim 1 .

8. the limiting member includes protrusions extending toward the rotor body, and the protrusions of the limiting member are at least partially inserted into the positioning holes and abut against the second axial ends of the magnets. The rotor assembly of claim 1 .

9. A motor comprising a stator and a rotor assembly according to any one of claims 1 to 8, wherein the rotor assembly is rotatably arranged within the stator. A motor characterized by:

10. A motor according to claim 9, A power tool characterized by:

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