A braking structure for the output shaft of a direct-drive motor and an electric tool

Abstract

This invention provides a braking structure for the output shaft of a direct-drive motor and an electric tool. The braking structure includes a fan blade and a brake pin. The direct-drive motor includes an outer rotor and a stator. The outer rotor includes a rotor yoke assembly, a fan blade, and an output shaft. The rotor yoke assembly includes a rotor yoke and several magnetic plates. The stator is fitted onto the output shaft, and the stator and output shaft are rotatably arranged relative to each other. The rotor yoke assembly is fitted onto the stator, and one end of the rotor yoke is fixedly connected to the output shaft via the fan blade. The brake pin is positioned opposite the fan blade, and the side of the fan blade facing the brake pin has at least one brake hole. By pressing the brake pin, the brake pin is inserted into the brake hole. Since the fan blade plays a rigid transmission role between the rotor yoke assembly and the output shaft, it has a certain strength. This invention uses the fan blade as the main body of the braking structure, simplifying the structure of the electric tool and reducing its height, allowing the electric tool to be used in confined spaces.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, and in particular to a braking structure for the output shaft of a direct drive motor and a power tool. Background Technology

[0002] An angle grinder, also known as a grinding machine or abrasive wheel machine, is a handheld power tool that uses a high-speed rotating cutting disc, abrasive wheel, wire wheel, polishing wheel, etc., as its working head for metal cutting, grinding, rust removal, polishing, and other operations.

[0003] The angle grinder's output shaft is fitted with an upper pressure plate and a working head, and a lower pressure plate is threadedly connected to it. The upper and lower pressure plates clamp the working head. However, when assembling or disassembling the working head, the output shaft rotates, making the process very inconvenient. Operators often need to use other external parts to fix the output shaft, which is time-consuming and laborious.

[0004] For gear-driven angle grinders, since the motor drives the output shaft through a reduction gear mechanism, a brake hole can be provided on the gear, and the output shaft can be braked by inserting a brake pin into the brake hole. However, for direct-drive angle grinders, since the motor directly drives the output shaft and no reduction gear mechanism is needed, a brake hole cannot be provided on the gear.

[0005] Therefore, how to brake the motor output shaft of a direct-drive angle grinder when disassembling and assembling the working head has become a technical problem that urgently needs to be solved in this field. Utility Model Content

[0006] To solve the above-mentioned technical problems, one embodiment of this utility model provides a braking structure for the output shaft of a direct drive motor, including a fan blade and a brake pin. The direct drive motor includes an outer rotor and a stator. The outer rotor includes a rotor yoke assembly, the fan blade, and an output shaft. The rotor yoke assembly includes a rotor yoke and several magnetic plates, with the magnetic plates fixed to the inner side of the rotor yoke. The stator is sleeved on the output shaft and is rotatably arranged relative to the output shaft. The rotor yoke assembly is sleeved on the stator, and one end of the rotor yoke is fixedly connected to the output shaft through the fan blade. The brake pin is arranged opposite to the fan blade, and the fan blade has at least one brake hole on its side facing the brake pin. By pressing the brake pin, the brake pin is inserted into the brake hole.

[0007] Optionally, the fan blade includes a web, an outer ring, and a plurality of blades. The web is fixedly fitted onto the output shaft. The outer ring is located on the outer periphery of the web and is fixedly connected to the rotor yoke assembly. The plurality of blades are spaced apart between the web and the outer ring. At least one brake hole is provided on the side of the web facing the brake pin.

[0008] Optionally, the web includes a central portion and at least one extension portion, the extension portion being located outside the central portion, the central portion having a shaft hole for fixing the sleeve onto the output shaft at its center, and the brake hole being disposed on the extension portion.

[0009] Optionally, the shaft hole includes a first hole section and a second hole section, wherein the first hole section is a circular hole section, and the circular hole section is interference-fitted to the output shaft;

[0010] The second hole segment is a non-circular hole segment, and the output shaft is also provided with a non-circular shaft segment adapted to the non-circular hole segment. The non-circular hole segment and the non-circular shaft segment cooperate; or / and, the second hole segment and the output shaft are provided with corresponding keyways, and the connecting keys are respectively embedded in the two keyways.

[0011] Optionally, the outer surface of the shaft segment that mates with the circular hole segment of the output shaft is further provided with knurling.

[0012] Optionally, the web includes at least two extensions, each extension being evenly distributed at intervals on the outer side of the central portion.

[0013] Optionally, the center portion has an axial extension section on the side opposite to the brake pin, and the shaft hole passes through the axial extension section.

[0014] Optionally, the web plate is provided with reinforcing ribs on the side facing away from the brake pin.

[0015] Optionally, the fan blades are made of aluminum alloy, magnesium alloy or zinc alloy.

[0016] Optionally, the fan blade is provided with an insert on the side facing the brake pin, and the brake hole is formed on the insert.

[0017] Another embodiment of this utility model provides an electric tool, including a head shell and the braking structure described in the above embodiment. The direct drive motor is disposed inside the head shell, and the stator is fixedly connected to the head shell through a bearing seat. The output end of the output shaft extends to the outside of the bearing seat. The brake pin is elastically disposed on the head shell.

[0018] Optionally, the brake pin includes an integrally formed pin body and a pressing part, the head shell is provided with a mounting through hole, and the pin body is elastically disposed in the mounting through hole by a return spring; the pressing part is disposed away from the fan blade.

[0019] Optionally, the power tool is an angle grinder.

[0020] Compared with the prior art, the technical solution of this utility model embodiment has the following beneficial effects:

[0021] In this invention, since the fan blade plays a rigid transmission role between the rotor yoke assembly and the output shaft, the fan blade has a certain strength. This invention uses the fan blade as the main body of the braking structure, which simplifies the structure of the power tool and can reduce the height of the power tool, so that the power tool can be used in narrow spaces.

[0022] Furthermore, the fan blades are made of high-strength aluminum alloy (magnesium alloy or zinc alloy), which increases the strength of the fan blades and prevents them from being damaged or detached from the output shaft during braking. Attached Figure Description

[0023] 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.

[0024] Figure 1 A schematic diagram of the braking structure of the output shaft of a direct drive motor provided in an embodiment of this utility model;

[0025] Figure 2 This is a schematic diagram of the structure of a fan blade provided in an embodiment of the present invention;

[0026] Figure 3 and Figure 4 A perspective view of the fan blades in different directions provided in an embodiment of the present utility model;

[0027] Explanation of reference numerals in the attached figures:

[0028] 1--Stator;

[0029] 2--Rotor yoke assembly;

[0030] 201--Magnetic disc;

[0031] 202--Rotor yoke;

[0032] 3--Head shell;

[0033] 4--Second bearing;

[0034] 5 -- Return spring;

[0035] 6--Brake pin;

[0036] 601 -- Pressing part;

[0037] 602 -- Pin body;

[0038] 7--Wind blades;

[0039] 701 -- Brake hole;

[0040] 702 -- Web plate;

[0041] 7021 -- Extension section;

[0042] 7022 -- Central Department;

[0043] 703 -- Outer Ring Road;

[0044] 704 -- Blade;

[0045] 705 -- Shaft hole;

[0046] 706 -- Axial extension section;

[0047] 707 -- Reinforcing rib;

[0048] 8 -- Output shaft;

[0049] 801 -- Output terminal;

[0050] 802 - Knurled finish;

[0051] 9--Bearing housing;

[0052] 10 -- First bearing;

[0053] 11--Third bearing. Detailed Implementation

[0054] 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.

[0055] 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.

[0056] Please refer to Figures 1 to 4 This utility model provides a braking structure for the output shaft of a direct drive motor, including a fan blade 7 and a brake pin 6. The direct drive motor includes an outer rotor and a stator 1. The outer rotor includes a rotor yoke assembly 2, a fan blade 7, and an output shaft 8. The rotor yoke assembly 2 includes a rotor yoke 202 and several magnetic plates 201, with the magnetic plates 201 fixed to the inner side of the rotor yoke 202. The stator 1 is sleeved on the output shaft 8, and the stator 1 is rotatably disposed relative to the output shaft 8. The rotor yoke assembly 2 is sleeved on the stator 1, and one end of the rotor yoke 202 is fixedly connected to the output shaft 8 through the fan blade 7. The brake pin 6 is disposed opposite to the fan blade 7, and the fan blade 7 has at least one brake hole 701 on its side facing the brake pin 6. By pressing the brake pin 6, the brake pin 6 is inserted into the brake hole 701.

[0057] In this invention, when the motor is working, an electromagnetic field is generated by the stator 1. The magnetic sheet 201 is driven by the electromagnetic force of the electromagnetic field to rotate the rotor yoke 202. The torque is transmitted to the output shaft 8 through the fan blade 7, causing the output shaft 8 to rotate. This enables the working head of the output end 801 of the output shaft 8 to rotate to perform operations such as cutting, grinding, rust removal, and polishing on metal.

[0058] Since the fan blade 7 plays a rigid transmission role between the rotor yoke assembly 2 and the output shaft 8, the fan blade 7 has a certain strength. This utility model uses the fan blade 7 as the main body of the braking structure, which simplifies the structure of the power tool and can reduce the height of the power tool, so that the power tool can be used in narrow spaces.

[0059] The working principle of this utility model is as follows: stop the motor and press the brake pin 6, while rotating the output shaft 8 so that the brake pin 6 is inserted into the brake hole 701, thereby braking the output shaft 8 and enabling the disassembly and assembly of the working head.

[0060] The present invention can provide a brake hole 701 on the structure of the fan blade 7, or add an insert to the fan blade 7 and provide a brake hole 701 on the insert. The present invention does not make specific limitations in this regard.

[0061] As one embodiment, a brake hole 701 is provided on the structure of the fan blade 7. Specifically, the fan blade 7 includes a web 702, an outer ring 703, and a plurality of blades 704. The web 702 is fixedly fitted onto the output shaft 8. The outer ring 703 is located on the outer periphery of the web 702 and is fixedly connected to the rotor yoke assembly 2. The plurality of blades 704 are spaced apart between the web 702 and the outer ring 703, with gaps between the blades 704 to facilitate heat dissipation from the motor. At least one brake hole 701 is provided on the side of the web 702 facing the brake pin 6.

[0062] This embodiment does not limit the specific shape and structure of the web 702, as long as a brake hole 701 can be provided on it. In one specific implementation, the web 702 includes a central portion 7022 and at least one extension 7021. The extension 7021 is located outside the central portion 7022. The central portion 7022 has a shaft hole 705 at its center for fixing a sleeve onto the output shaft 8. The brake hole 701 is provided on the extension 7021.

[0063] This embodiment does not limit the shape of the shaft hole 705; it can be a circular hole or a non-circular hole. If the shaft hole 705 is a circular hole, the torque is transmitted between the fan blade 7 and the output shaft 8 through friction, which can easily lead to torque transmission failure or efficiency reduction. To avoid this risk, in one specific embodiment, the shaft hole 705 includes a first hole section and a second hole section. The first hole section is a circular hole section, which is interference-fitted to the output shaft 8. To increase the friction between the circular hole section and the output shaft 8, knurling 802 can be provided on the outer surface of the shaft section of the output shaft 8 that mates with the circular hole section.

[0064] In one specific implementation, the second bore section is a non-circular bore section, and the output shaft 8 is also provided with a non-circular shaft section adapted to the non-circular bore section, with the non-circular bore section cooperating with the non-circular shaft section; or / and, the second bore section and the output shaft 8 are provided with corresponding keyways, and connecting keys are respectively embedded in these two keyways. Therefore, the second bore section and the output shaft 8 transmit torque through a rigid mechanical engagement instead of friction, thereby achieving higher torque reliability, positioning accuracy, and load-bearing capacity.

[0065] This embodiment does not limit the shape of non-circular hole segments and non-circular shaft segments; for example, they can be D-shaped, flat square, polygonal, etc.

[0066] In this embodiment, the number of brake holes 701 is not limited; there can be one or more. Since the brake holes 701 are formed on the extensions 7021, the number of extensions 7021 is equal to the number of brake holes 701. To ensure the structural symmetry of the fan blade 7, the web 702 further includes at least two extensions 7021, with each extension 7021 evenly distributed on the outer side of the central portion 7022.

[0067] To further increase the reliability of the connection between the fan blade 7 and the output shaft 8, the center portion 7022 is provided with an axial extension section 706 on the side opposite to the brake pin 6, and the shaft hole 705 passes through the axial extension section 706.

[0068] To further increase the strength of the fan blade 7, the web plate 702 is provided with a reinforcing rib 707 on the side opposite to the brake pin 6, and / or the fan blade 7 is made of aluminum alloy, magnesium alloy or zinc alloy.

[0069] In a second embodiment, a brake hole 701 is provided on the insert of the fan blade 7. Specifically, the fan blade 7 has an insert on the side facing the brake pin 6, and the brake hole 701 is formed on the insert.

[0070] This embodiment does not limit the connection relationship between the fan blade 7 and the insert. For example, it can be made as a single piece, or it can be connected by a fixed assembly method.

[0071] The braking structure of the motor output shaft 8 provided by this utility model can be applied to many power tools. Taking an angle grinder as an example, this angle grinder is a direct-drive angle grinder.

[0072] Specifically, another embodiment of this utility model also provides an angle grinder, which includes a head shell 3 and the braking structure described in the above embodiment. The direct drive motor is disposed inside the head shell 3. The stator 1 is fixedly connected to the head shell 3 through a bearing seat 9. The bearing seat 9 and the head shell 3 are fixed by threads. The output end 801 of the output shaft 8 extends to the outside of the bearing seat 9. The brake pin 6 is elastically disposed on the head shell 3.

[0073] In one specific implementation, one end of the stator 1 is fixed to the head housing 3 via a bearing seat 9, and the output end 801 of the output shaft 8 passes through the bearing seat 9. Furthermore, the output shaft 8 is rotatably connected to the bearing seat 9 via a first bearing 10, and the non-output end of the output shaft 8 is rotatably connected to the head housing 3 via a second bearing 4. In this embodiment, the output end 801 of the output shaft 8 is the end connected to the working head, and the non-output end of the output shaft 8 is the end opposite to the output end 801.

[0074] In this embodiment, the stator 1 includes a stator core and several coils. The outer circumference of the stator core is provided with several teeth at intervals, and the coils are wound around the teeth. The stator core is sleeved on the output shaft 8, and the stator core and the output shaft 8 are rotatably connected by a third bearing 11.

[0075] This embodiment does not limit the specific type of working head, such as a cutting disc, grinding wheel, wire wheel, polishing wheel, etc.

[0076] In this embodiment, the fan blade 7 can be closer to the non-output end of the output shaft 8 relative to the stator 1 and the rotor yoke assembly 2, or it can be closer to the output end 801 of the output shaft 8 relative to the stator 1 and the rotor yoke assembly 2. This embodiment does not impose specific limitations on this.

[0077] To facilitate the installation of the brake pin 6, the fan blade 7 is positioned closer to the non-output end of the output shaft 8 relative to the stator 1 and the rotor yoke assembly 2, and the brake pin 6 is located on the side of the head housing 3 opposite to the fan blade 7.

[0078] The brake pin 6 includes an integrally formed pin body 602 and a pressing part 601. The head shell 3 is provided with a mounting through hole. The pin body 602 is elastically disposed in the mounting through hole by a return spring 5. The pressing part 601 is disposed away from the fan blade 7.

[0079] During braking, pressing the pressing part 601 causes the pin body 602 to insert into the brake hole 701, thereby braking the motor output shaft 8. After the working head is disassembled and assembled, the pressing part 601 is released, and the pin body 602 is reset by the action of the return spring 5, thereby disengaging from the brake hole 701.

[0080] 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 braking structure for the output shaft of a direct-drive motor, characterized in that, The direct-drive motor includes a fan blade and a brake pin. It comprises an outer rotor and a stator. The outer rotor includes a rotor yoke assembly, the fan blade, and an output shaft. The rotor yoke assembly includes a rotor yoke and several magnetic plates, with the magnetic plates fixed to the inner side of the rotor yoke. 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 is fixedly connected to the output shaft via the fan blade. The brake pin is positioned opposite the fan blade, and the fan blade has at least one brake hole on its side facing the brake pin. By pressing the brake pin, the brake pin is inserted into the brake hole.

2. The braking structure according to claim 1, characterized in that, The fan blade includes a web, an outer ring, and a plurality of blades. The web is fixedly fitted onto the output shaft. The outer ring is located on the outer periphery of the web and is fixedly connected to the rotor yoke assembly. The plurality of blades are spaced apart between the web and the outer ring. At least one brake hole is provided on the side of the web facing the brake pin.

3. The braking structure according to claim 2, characterized in that, The web includes a central portion and at least one extension portion, the extension portion being located outside the central portion, the central portion having a shaft hole for fixing the sleeve onto the output shaft at its center, and the brake hole being disposed on the extension portion.

4. The braking structure according to claim 3, characterized in that, The shaft hole includes a first hole section and a second hole section, wherein the first hole section is a circular hole section, and the circular hole section is interference-fitted to the output shaft; The second hole segment is a non-circular hole segment, and the output shaft is also provided with a non-circular shaft segment adapted to the non-circular hole segment. The non-circular hole segment and the non-circular shaft segment cooperate; or / and, the second hole segment and the output shaft are provided with corresponding keyways, and the connecting keys are respectively embedded in the two keyways.

5. The braking structure according to claim 4, characterized in that, The outer surface of the shaft segment that mates with the circular hole segment of the output shaft is also provided with knurling.

6. The braking structure according to claim 3, characterized in that, The web includes at least two extensions, each extension being evenly distributed at intervals on the outer side of the central portion.

7. The braking structure according to claim 3, characterized in that, The central portion has an axial extension section on the side opposite to the brake pin, and the shaft hole passes through the axial extension section.

8. The braking structure according to claim 3, characterized in that, The web plate has reinforcing ribs on the side facing away from the brake pin.

9. The braking structure according to claim 1, characterized in that, The fan blades are made of aluminum alloy, magnesium alloy or zinc alloy.

10. The braking structure according to claim 1, characterized in that, The fan blade has an insert on the side facing the brake pin, and the brake hole is formed on the insert.

11. A power tool, characterized in that, The device includes a head housing and a braking structure as described in any one of claims 1 to 10, wherein the direct drive motor is disposed inside the head housing, the stator is fixedly connected to the head housing via a bearing seat, the output end of the output shaft extends to the outside of the bearing seat, and the brake pin is elastically disposed on the head housing.

12. The power tool according to claim 11, characterized in that, The brake pin includes an integrally formed pin body and a pressing part. The head shell is provided with a mounting through hole, and the pin body is elastically disposed in the mounting through hole by a return spring. The pressing part is disposed away from the fan blade.

13. The power tool according to claim 11, characterized in that, The power tool is an angle grinder.

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