Magnetic sheet anti-falling structure of outer rotor motor and electric tool

Abstract

The utility model provides a kind of magnetic sheet anti-falling structure and electric tool of outer rotor motor, outer rotor motor includes outer rotor and stator, outer rotor includes rotor yoke assembly, fan blade and output shaft, stator is sleeved on output shaft, and stator is relatively rotatably arranged with output shaft;Rotor yoke assembly is sleeved on stator, and one end of rotor yoke assembly is fixedly connected with output shaft by fan blade;Rotor yoke assembly includes rotor yoke and several magnetic sheets, and rotor yoke is the cylindrical structure of two ends opening, and the inner wall of rotor yoke is distributed several close slots along the circumferential direction, and the close slot is arranged along the axial direction of rotor yoke;The shape of magnetic sheet and close slot is matched, and magnetic sheet is embedded in close slot to realize radial fixation, and magnetic sheet is also bonded with close slot by glue, to realize axial fixation;The side of fan blade towards rotor yoke is arranged several convex shapes matched with the shape of close slot, and the convex shape is embedded in close slot, so that the convex shape and close slot are interference fit.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, and in particular to a magnetic sheet anti-detachment structure for an external rotor motor and a power tool. Background Technology

[0002] Currently, in external rotor motors, several magnetic sheets are directly bonded to the inner wall of the rotor yoke with adhesive. Therefore, when the adhesive fails or the load torque is too high, the magnetic sheets will fall off, which will have an adverse effect on the motor's operational safety, performance stability, and surrounding components. Utility Model Content

[0003] To solve the above-mentioned technical problems, one embodiment of this utility model provides a magnetic sheet anti-detachment structure for an external rotor motor. The external rotor motor includes an external rotor and a stator. The external rotor includes a rotor yoke assembly, a fan blade, and an output shaft. The stator is sleeved on the output shaft and is rotatably disposed relative to the output shaft. The rotor yoke assembly is sleeved on the stator, and one end of the rotor yoke assembly is fixedly connected to the output shaft through the fan blade. The rotor yoke assembly includes a rotor yoke and several magnetic sheets. The yoke is a cylindrical structure open at both ends. The inner wall of the rotor yoke has several constricted slots spaced circumferentially, and the slots are arranged along the axial direction of the rotor yoke. The magnetic sheet is adapted to the shape of the slot and is embedded in the slot to achieve radial fixation. The magnetic sheet is also bonded to the slot with glue to achieve axial fixation. The fan blade has several protrusions spaced on the side facing the rotor yoke that are adapted to the shape of the slot. The protrusions are embedded in the slot, so that the protrusions and the slots are interference fit.

[0004] Optionally, the inner wall of the rotor yoke is provided with a plurality of reinforcing ribs spaced apart circumferentially, and the reinforcing ribs are arranged along the axial direction of the rotor yoke, with the groove formed between two adjacent reinforcing ribs.

[0005] Optionally, the outer periphery of the fan blade is provided with an outer ring on the side facing the rotor yoke, and the outer ring is inserted into the rotor yoke; a plurality of the protrusions are spaced apart on the end face of the outer ring facing the rotor yoke.

[0006] Optionally, at the end furthest from the fan blade, the end face of the reinforcing rib is flush with the end face of the rotor yoke; at the end closer to the fan blade, the end face of the reinforcing rib is located inside the rotor yoke and has a certain distance between it and the end face of the rotor yoke; the outer ring is located within this space and is interference-fitted with the rotor yoke.

[0007] Optionally, the outer ring is also bonded to the rotor yoke with adhesive.

[0008] Optionally, the slot opening faces the central axis of the rotor yoke, and the width of the slot opening is smaller than the width of the slot bottom.

[0009] Optionally, the rotor yoke is formed by internal broaching, extrusion, stretching, or stacking and riveting of laminations.

[0010] Another embodiment of the present invention provides an electric tool, including a housing and the magnetic sheet anti-detachment structure described in the above embodiment, wherein the external rotor motor is disposed inside the housing, and the stator is fixed relative to the housing.

[0011] Optionally, the stator includes a stator core and several coils. Several teeth are spaced apart on the outer periphery of the stator core, and the coils are wound on the teeth. The stator core is also fixedly connected to the housing through a bearing seat. The output end of the output shaft of the external rotor motor passes through the bearing seat, and the output shaft is rotatably connected to the bearing seat through a first bearing. The non-output end of the output shaft is rotatably connected to the housing through a second bearing.

[0012] Optionally, at least one brake hole is provided on one side of the fan blade, and a brake pin corresponding to the brake hole is provided on the housing. By pressing the brake pin, the brake pin is inserted into the brake hole.

[0013] Compared with the prior art, the technical solution of this utility model embodiment has the following beneficial effects: This utility model provides a magnetic sheet anti-detachment structure for an external rotor motor. In the rotor yoke assembly, the magnetic sheet is embedded in the slot of the rotor yoke. The magnetic sheet is fixed by radial fixation through the slot and by adhesive bonding. Therefore, the magnetic sheet will not fall off even under a large torque.

[0014] Similarly, this invention embeds the protrusion of the fan blade into the slot of the inner wall of the rotor yoke, and fixes the fan blade and the rotor yoke by interference fit. Therefore, even under a large torque, the rotor yoke will not detach from the fan blade. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the magnetic sheet anti-detachment structure of an external rotor motor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the rotor yoke provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an angle grinder provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a fan blade provided in an embodiment of the present invention; Figure 5 A perspective view of a fan blade provided in an embodiment of the present utility model; Explanation of reference numerals in the attached figures: 1--First bearing; 2--Bearing housing; 3--Stator; 301 -- Stator core; 302 -- Coil; 4-- Output shaft; 401 -- Output terminal; 402 -- Non-circular shaft segment; 5--Outer rotor; 501 -- Magnetic sheet; 502 -- Rotor yoke; 5021 -- Reinforcing rib; 5022 -- Card slot; 50221 -- Groove; 50222 -- Bottom of the tank; 6--Wind blades; 601 -- Protrusion; 602 -- Brake hole; 603 -- Non-circular hole segment; 604 -- Web; 605 -- Outer Ring Road; 606 -- Blade; 607 -- Reinforcing rib; 608 -- Axial extension section; 7--Second bearing; 8--Shell; 9--Brake pin; 901 -- Pressing part; 902 -- Pin body; 10 -- Return spring; 11--Third bearing. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The terms "above" and "over," and any variations thereof, are intended to describe positional relationships and do not imply direct contact between the described objects.

[0019] Please refer to Figures 1 to 5 This utility model provides a magnetic sheet anti-detachment structure for an external rotor motor. The external rotor motor includes an external rotor and a stator 3. The external rotor includes a rotor yoke assembly 5, a fan blade 6, and an output shaft 4. The stator 3 is sleeved on the output shaft 4, and the stator 3 is rotatably disposed relative to the output shaft 4. The rotor yoke assembly 5 is sleeved on the stator 3, and one end of the rotor yoke assembly 5 is fixedly connected to the output shaft 4 through the fan blade 6. The rotor yoke assembly 5 includes a rotor yoke 502 and a plurality of magnetic sheets 501. The rotor yoke 502 is a cylindrical structure with open ends. The inner wall of the rotor yoke 502 has a plurality of tapered grooves 5022 distributed circumferentially, and the grooves 5022 are arranged along the axial direction of the rotor yoke 502. The magnetic sheet 501 is shaped to fit the slot 5022. The magnetic sheet 501 is embedded in the slot 5022 for radial fixation, and the magnetic sheet 501 is also bonded to the slot 5022 with adhesive for axial fixation. A plurality of protrusions 601, shaped to fit the slot 5022, are spaced apart on the side of the fan blade 6 facing the rotor yoke 502. The protrusions 601 are embedded in the slot 5022, resulting in an interference fit between the protrusions 601 and the slot 5022.

[0020] In this invention, when the external rotor motor is working, an electromagnetic field is generated by the stator 3. The magnetic sheet 501 is driven by the electromagnetic force of the electromagnetic field to rotate the rotor yoke 502. The torque is transmitted to the output shaft 4 through the fan blade 6. The rotor yoke 502 causes the output shaft 4 to rotate, thereby realizing the rotation of the working head to perform operations such as cutting, grinding, rust removal, and polishing on metal.

[0021] In this invention, the magnetic sheet 501 is embedded in the slot 5022 on the inner wall of the rotor yoke 502. The magnetic sheet 501 is axially fixed by radial fixation through the slot 5022 and adhesive bonding. Therefore, the magnetic sheet 501 will not fall off even under a large torque.

[0022] Similarly, in this invention, the protrusion 601 of the fan blade 6 is embedded in the slot 5022 of the inner wall of the rotor yoke 502. The fan blade 6 and the rotor yoke 502 are fixed by interference fit. Therefore, even under a large torque, the rotor yoke 502 will not detach from the fan blade 6.

[0023] In this embodiment, the opening 50221 of the slot 5022 faces the central axis of the rotor yoke 502. The slot 5022 is a tapered slot, meaning the width of the opening 50221 is smaller than the width of the bottom 50222. The bottom 50222 of the slot 5022 is opposite to the opening 50221, located on the inner wall of the rotor yoke 502. The shape of the sidewall of the slot 5022 is not limited in this embodiment; it can be an arc-shaped surface or a flat surface. The shape and size of the protrusions 601 of the magnetic sheet 501 and the fan blade 6 are adapted to the slot 5022.

[0024] This embodiment does not limit the number of card slots 5022, and can be set according to actual usage requirements.

[0025] In one specific implementation, the inner wall of the rotor yoke 502 is provided with a plurality of reinforcing ribs 5021 spaced circumferentially, and the reinforcing ribs 5021 are arranged along the axial direction of the rotor yoke 502, with a groove 5022 formed between two adjacent reinforcing ribs 5021. This embodiment, by adding reinforcing ribs 5021 to the inner wall of the rotor yoke 502, can, on the one hand, fix the magnetic sheet 501, and on the other hand, achieve a more reliable fit with the fan blade 6, thereby increasing the torsional resistance.

[0026] In this specific embodiment, the length direction of the reinforcing rib 5021 is the length direction of the rotor yoke 502, that is, the length direction of the reinforcing rib 5021 is parallel to the axial direction of the rotor yoke 502, the width direction of the reinforcing rib 5021 is the circumferential direction of the rotor yoke 502, and the thickness direction of the reinforcing rib 5021 is the radial direction of the rotor yoke 502.

[0027] In this embodiment, an outer ring 605 is provided on the outer periphery of the fan blade 6 facing the rotor yoke 502, and the outer ring 605 is inserted into the rotor yoke 502; a plurality of protrusions 601 are spaced apart on the end face of the outer ring 605 facing the rotor yoke 502.

[0028] At the end furthest from the fan blade 6, the end face of the reinforcing rib 5021 is flush with the end face of the rotor yoke 502. At the end closer to the fan blade 6, the end face of the reinforcing rib 5021 is located within the rotor yoke 502, and there is a certain distance between it and the end face of the rotor yoke 502; the outer ring 605 is located within this space and is interference-fitted with the rotor yoke 502.

[0029] In one specific implementation, the card slot 5022 is a dovetail groove structure, and the magnetic sheet 501 and the protrusion 601 are both dovetail tenon structures adapted to the shape of the card slot 5022.

[0030] In this embodiment, the magnetic sheet 501 is first inserted into the card slot 5022, so that the magnetic sheet 501 and the card slot 5022 are radially fixed. In order to increase the reliability of the fixed connection between the magnetic sheet 501 and the card slot 5022, the magnetic sheet 501 is also bonded to the card slot 5022 by dispensing adhesive, thereby preventing the magnetic sheet 501 from moving axially.

[0031] The outer ring 605 is inserted into the rotor yoke 502, resulting in an interference fit between the outer ring 605 and the rotor yoke 502. The protrusion 601 on the outer ring 605 is inserted into the slot 5022, resulting in an interference fit between the protrusion 601 and the slot 5022. To further increase the reliability of the fixed connection between the fan blade 6 and the rotor yoke 502, adhesive is applied to bond the outer ring 605 to the rotor yoke 502.

[0032] In this embodiment, the center of the fan blade 6 is also provided with a shaft hole for fixing the outer sleeve on the output shaft 4.

[0033] This embodiment does not limit the shape of the shaft hole; it can be a circular hole or a non-circular hole. If the shaft hole is circular, the torque is transmitted between the fan blade 6 and the output shaft 4 through friction, which can easily lead to torque transmission failure or efficiency reduction. To avoid this risk, in one specific embodiment, the shaft hole includes a first hole segment and a second hole segment. The first hole segment is a circular hole segment, which is interference-fitted to the output shaft 4. To increase the friction between the circular hole segment and the output shaft 4, knurling 403 can be provided on the outer surface of the shaft segment of the output shaft 4 that mates with the circular hole segment.

[0034] In one specific implementation, the second bore section is a non-circular bore section 603, and the output shaft 4 is also provided with a non-circular shaft section 402 adapted to the non-circular bore section 603, with the non-circular bore section 603 cooperating with the non-circular shaft section 402; or / and, the second bore section and the output shaft 4 are provided with corresponding keyways, and connecting keys are respectively embedded in these two keyways. Therefore, the second bore section and the output shaft 4 transmit torque through a rigid mechanical engagement instead of friction, thereby achieving higher torque reliability, positioning accuracy, and load-bearing capacity.

[0035] This embodiment does not limit the shape of the non-circular hole segment 603 and the non-circular shaft segment 402, such as D-shaped, flat square, polygonal, etc.

[0036] This embodiment does not limit the processing technology of the rotor yoke 502 with the slot 5022. For example, the rotor yoke 502 can be formed by internal hole broaching, extrusion forming, stretch forming, or stamping and riveting.

[0037] The magnetic sheet anti-detachment structure of the external rotor motor provided by this utility model can be applied to various power tools, such as grinding wheels and angle grinders; it can be a direct-drive power tool or a gear-driven power tool, and this utility model does not limit it in this regard.

[0038] Another embodiment of this utility model provides an electric tool, including a housing 8 and the magnetic sheet anti-detachment structure described in the above embodiment, wherein the external rotor motor is disposed in the housing 8, and the stator 3 is fixed relative to the housing 8.

[0039] In this embodiment, the stator 3 includes a stator core 301 and several coils 302. The stator core 301 has several teeth spaced apart on its outer circumference, and the coils 302 are wound around these teeth. The stator core 301 is also fixedly connected to a bearing housing 2, which is fixedly connected to the housing 8. The output end 401 of the output shaft 4 of the external rotor motor passes through the bearing housing 2, and the output shaft 4 is rotatably connected to the bearing housing 2 via a first bearing 1. The non-output end of the output shaft 4 is rotatably connected to the housing 8 via a second bearing 7. In this embodiment, the output end 401 of the output shaft 4 is the end connected to the working head, and the non-output end of the output shaft 4 is the end opposite to the output end 401. The stator core 301 and the output shaft 4 are also rotatably connected via a third bearing 11.

[0040] This embodiment does not limit the specific type of working head, such as a cutting disc, grinding wheel, wire wheel, polishing wheel, etc.

[0041] Taking a direct-drive power tool as an example, when disassembling and assembling the working head, the output shaft 4 of the external rotor motor rotates, making disassembly and assembly very inconvenient. Operators often need to use other external parts to fix the output shaft 4, which is time-consuming and laborious. To solve this technical problem, this embodiment provides at least one brake hole 602 on one side of the fan blade 6, and a brake pin 9 corresponding to the brake hole 602 is provided on the housing 8. By pressing the brake pin 9, the brake pin 9 is inserted into the brake hole 602, thereby braking the output shaft 4 and enabling the disassembly and assembly of the working head.

[0042] In this embodiment, the fan blade 6 can be closer to the non-output end of the output shaft 4 than the stator 3 and the rotor yoke 502, or it can be closer to the output end 401 of the output shaft 4 than the stator 3 and the rotor yoke 502. This embodiment does not impose any specific restrictions on this.

[0043] As a specific implementation, the fan blade 6 can be closer to the non-output end of the output shaft 4 than the stator 3 and the rotor yoke 502, in order to facilitate the installation of the brake pin 9 on the housing 8.

[0044] In order to facilitate the automatic reset of the brake pin 9 when it is released, the brake pin 9 is elastically set on the housing 8 by a reset spring 10.

[0045] Specifically, the brake pin 9 includes an integrally formed pin body 902 and a pressing part 901. The housing 8 is provided with a mounting through hole. The pin body 902 is elastically disposed in the mounting through hole by a return spring 10. The pressing part 901 is disposed away from the fan blade 6.

[0046] During braking, pressing the pressing part 901 causes the pin body 902 to insert into the brake hole 602, thereby braking the motor output shaft 4. After the working head is disassembled and assembled, the pressing part 901 is released, and the pin body 902 is reset by the action of the return spring 10, thereby disengaging from the brake hole 602.

[0047] Braking holes 602 can be provided on the structure of the fan blade 6 or on the insert of the fan blade 6. This embodiment does not impose any specific restrictions on this.

[0048] In one specific embodiment, the fan blade 6 includes a web 604, an outer ring 605, and a plurality of blades 606. The web 604 has a non-circular hole 603 at its center. The fan blade 6 is fitted onto the output shaft 4 by an interference fit, and is partially fitted onto the non-circular shaft section 402 of the output shaft 4 by the non-circular hole 603.

[0049] The outer ring 605 is located on the outer periphery of the web 604. A plurality of protrusions 601 are provided circumferentially on the side of the outer ring 605 facing the rotor yoke 502. The protrusions 601 are embedded in the slots 5022 of the rotor yoke 502.

[0050] A plurality of blades 606 are spaced apart between the web 604 and the outer ring 605, and there are gaps between the plurality of blades 606 to facilitate heat dissipation of the motor.

[0051] To further increase the reliability of the connection between the fan blade 6 and the output shaft 4, an axial extension section 608 is provided on the side of the web plate 604 facing away from the brake pin 6. The axial extension section 608 is fixedly sleeved on the knurled 403 of the output shaft 4.

[0052] To further increase the strength of the fan blade 6, the web plate 604 is provided with a reinforcing rib 607 on the side opposite to the brake pin 6, and / or the fan blade 6 is made of aluminum alloy, magnesium alloy, or zinc alloy.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A magnetic sheet anti-detachment structure for an external rotor motor, characterized in that, The external rotor motor includes an external rotor and a stator. The external rotor includes a rotor yoke assembly, a fan blade, and an output shaft. The stator is fitted onto the output shaft and is rotatably arranged relative to the output shaft. The rotor yoke assembly is fitted onto the stator, and one end of the rotor yoke assembly is fixedly connected to the output shaft via the fan blade. The rotor yoke assembly includes a rotor yoke and several magnetic plates. The rotor yoke is a cylindrical structure with open ends. The inner wall of the rotor yoke has several tapered slots spaced circumferentially, and the slots are arranged axially along the rotor yoke. The magnetic plates are adapted to the shape of the slots and are embedded in the slots for radial fixation. The magnetic plates are also bonded to the slots with adhesive for axial fixation. The fan blade has several protrusions spaced on the side facing the rotor yoke that are adapted to the shape of the slots. The protrusions are embedded in the slots, so that the protrusions and the slots are interference-fitted.

2. The magnetic sheet anti-detachment structure according to claim 1, characterized in that, The inner wall of the rotor yoke is provided with a plurality of reinforcing ribs spaced apart circumferentially, and the reinforcing ribs are arranged along the axial direction of the rotor yoke, with the groove formed between two adjacent reinforcing ribs.

3. The magnetic sheet anti-detachment structure according to claim 2, characterized in that, The outer periphery of the fan blade is provided with an outer ring on the side facing the rotor yoke, and the outer ring is inserted into the rotor yoke; a plurality of the protrusions are spaced apart on the end face of the outer ring facing the rotor yoke.

4. The magnetic sheet anti-detachment structure according to claim 3, characterized in that, At the end furthest from the fan blade, the end face of the reinforcing rib is flush with the end face of the rotor yoke; at the end closest to the fan blade, the end face of the reinforcing rib is located inside the rotor yoke and has a certain distance between it and the end face of the rotor yoke; the outer ring is located within this space and is interference-fitted with the rotor yoke.

5. The magnetic sheet anti-detachment structure according to claim 3, characterized in that, The outer ring is also bonded to the rotor yoke with adhesive.

6. The magnetic sheet anti-detachment structure according to claim 1, characterized in that, The slot opening faces the central axis of the rotor yoke, and the width of the slot opening is less than the width of the slot bottom.

7. The magnetic sheet anti-detachment structure according to claim 1, characterized in that, The rotor yoke is formed by internal hole broaching, extrusion, stretching, or stacking and riveting of laminations.

8. A power tool, characterized in that, The device includes a housing and a magnetic sheet anti-detachment structure as described in any one of claims 1 to 7, wherein the outer rotor motor is disposed within the housing, and the stator is fixed relative to the housing.

9. The power tool according to claim 8, characterized in that, The stator includes a stator core and several coils. Several teeth are spaced apart on the outer circumference of the stator core, and the coils are wound on the teeth. The stator core is also fixedly connected to the housing through a bearing seat. The output end of the output shaft of the external rotor motor passes through the bearing seat, and the output shaft is rotatably connected to the bearing seat through a first bearing. The non-output end of the output shaft is rotatably connected to the housing through a second bearing.

10. The power tool according to claim 8, characterized in that, At least one brake hole is provided on one side of the fan blade, and a brake pin corresponding to the brake hole is provided on the housing. By pressing the brake pin, the brake pin is inserted into the brake hole.

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