Rotor for external rotor electric machine
By designing an angled metal strip bracket and welding connection method, the problems of high stacking of rotor attachment metal sheets in the prior art and difficult to adjust the axial length are solved, and low-cost, flexible attachment methods and improved mechanical stability are achieved.
Patent Information
- Application Number
- CN202421723905.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-21
- Filing Date
- 2024-07-19
- Publication Date
- 2025-06-10
- Estimated Expiration
- 2034-07-19
AI Technical Summary
The existing rotors for external rotor motors are costly and difficult to achieve flexible axial length adjustment when attaching metal sheet stacks.
By designing an angled metal strip bracket, the metal sheet stack is pressed against the bracket in the axial direction, and the bracket and stack are connected by welding, an economical and flexible attachment method is achieved.
Low-cost and reliable metal sheet stack attachment is achieved, able to adapt to the needs of different axial lengths and improve the mechanical stability of the rotor.
Smart Images
Figure CN222966783U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a rotor for an outer rotor motor. Background Art
[0002] Such a rotor includes a stack of steel annular sheets, permanent magnets attached to the inner side of the stack, and a bracket with a hub for a shaft and attached to the stack. The stack must be attached to the bracket. Summary of the Utility Model
[0003] The purpose of the utility model is to utilize the bracket of the rotor for the outer rotor motor to achieve attachment to the stack of metal sheets at low cost.
[0004] In the rotor according to the utility model, the stack is pressed against the bracket in the axial direction by a bracket against the outer side of the stack. For example, these brackets can be designed as clamps and can reliably fasten the stack to the bracket.
[0005] An advantageous improvement of the utility model is that each bracket includes two metal strips, each metal strip having an angled end, and the metal strips are located adjacent to each other on the outer side of the stack, and the metal strips are welded to each other and / or welded to the stack. In this way, the brackets can be designed very economically. In particular, the axial length of the stack can vary within a wide range according to performance requirements, and the same metal strips can still be used to form the brackets. Since each metal strip only has a single angled end, the metal strips in question do not need to extend over the entire axial length of the stack. One of the two metal strips in each pair of metal strips extends from the bracket beyond the center of the stack, and the other of the pair of metal strips extends from the end of the stack away from the bracket beyond the center of the stack of metal sheets.
[0006] By welding the metal strips in a pair of metal strips to each other and / or to the stack while pressing the stack against the bracket in the axial direction, it can be achieved that the stack is subsequently continuously pressed against the bracket by the brackets with preloading, especially if the welding only extends over a partial axial length of the stack, for example, over one-tenth to one-third of the axial length of the stack.
[0007] Another advantageous improvement of the utility model is that the metal strips in a pair of metal strips are arranged at a certain distance from each other on the outer side of the stack of sheets, and the two metal strips are welded together by a weld seam for bridging the distance between the two metal strips. Advantageously, the sheets of the stack can also be welded together thereby, which increases the mechanical stability of the rotor.
[0008] Another advantageous improvement of the present utility model lies in that the sheet stack has radial protrusions on its outer side, and the bracket is arranged on these protrusions. The welding will locally melt the material of the stack, and usually change the microstructure of the material there, which will damage its soft magnetic properties. The steel of the sheet stack is usually electrical steel, that is, soft magnetic steel (for example, silicon steel). Since the welding occurs in the radial protrusions on the outer side of the sheet stack, any change in the magnetic properties of the material still has a negligible impact on the back ring formed by the sheet stack.
[0009] The radial protrusions on the outer side of the stack can also be used to form a hub connection between the sheet stack and the bracket (for example, by a bracket with slots, and the protrusions of the stack engage into the slots). In this way, a connection that can absorb both axial force and torque can be established. Description of the Drawings
[0010] Referring to the accompanying drawings, more details and advantages of the present utility model are provided in the embodiments of the present utility model. In different drawings, the same and corresponding components have corresponding reference numerals.
[0011] Figure 1 An example of a rotor for an outer rotor motor according to the present utility model is shown;
[0012] Figure 2 Shown is Figure 1 a schematic detailed view of the outer side of the rotor in
[0013] Figure 3 a schematic detailed view of the outer side of the rotor of another embodiment is shown;
[0014] Figure 4 a detailed view of another design example before welding is shown;
[0015] Figure 5 A detailed view of Figure 4 using laser welding is shown; and
[0016] Figure 6 a detailed view of another embodiment using tungsten inert gas welding is shown. Detailed Description of the Invention
[0017] Figure 1 A rotor of an electric motor is shown. More precisely, a rotor of an outer rotor motor is shown. The rotor has an annular sheet stack 1 made of ferromagnetic steel (for example, electrical steel or other soft magnetic steel). The individual sheets in the sheet stack 1 can be annular sheets, or each sheet can only form a ring segment. The permanent magnet 2 (for example, based on Nd 2 Fe 14The permanent magnet 2 (of B) is attached to the interior of the stack 1. The permanent magnet 2 can be arranged, for example, in a groove of the stack 1 and fixed in the groove using an adhesive. The sheet stack 1 is attached to the bracket 4 by means of a support 3, and the bracket 4 has a hub 7 for the shaft.
[0018] The support 3 is located on the outer side of the sheet stack 1 and axially presses the sheet stack 1 against the bracket 4 (in the illustrated embodiment, presses the sheet stack into the bracket). Each support 3 is formed by two metal strips 3a, 3b, each of the metal strips 3a, 3b having an angled end 5, and the metal strips 3a, 3b are located adjacent to each other on the outer side of the sheet stack 1, and the metal strips 3a, 3b are welded to each other and welded to the sheet stack 1. In particular, as Figure 2 and Figure 3 shown, such a support 3 can advantageously be used for stacks 1 of different lengths. A shorter sheet stack 1 is shown in Figure 2 and a longer sheet stack 1 is shown in Figure 3 . The longer the sheet stack 1, the shorter the portion of the sheet stack where the two metal strips 3a, 3b forming the support 3 are located.
[0019] There is a gap between the two metal strips 3a, 3b that together form the support 3, and in this gap there is a weld 6 that connects the two metal strips 3a, 3b to each other and to the sheet stack 1. One of the two metal strips of a pair of metal strips forming the support 3, the metal strip 3a, clamps one end of the metal sheet stack 1 with its angled end 5, and the other metal strip 3b of the pair of metal strips clamps the bracket 4 at the other end of the metal sheet stack 1. As Figure 2 and Figure 3 shown, the angled end 5 of the metal strip 3a rests on one end face of the sheet stack 1 at one end of the rotor, and the angled end 5 of the other metal strip 3b of the pair of metal strips forming the support 3 rests on the outer surface of the radially extending bracket 4 at the other end of the rotor.
[0020] The metal strips 3a, 3b each have an increased width at their angled ends 5. In the illustrated embodiment, the width of the end 5 is at least as large as the width of the support 3 at the widest point on the outer side of the sheet stack 1 in the radial direction. In the illustrated embodiment, the width of the end 5 is more than twice the width of the adjacent portions of the metal strips 3a, 3b. The metal strips 3a, 3b of a pair of metal strips forming the support 3 are identical in design, i.e., they are the same within their manufacturing tolerances.
[0021] The sheet stack 1 may have radial projections 8 on its outer side. In the illustrated embodiment, the brackets 3 are arranged on these projections 8, each projection 8 extending over the entire axial length of the sheet stack 1. The projections 8 are located in the grooves of the carrier 4, which in the illustrated embodiment are formed between the axial projections 9 of the carrier 4. The axial projections 9 extend only over a part of the axial length of the sheet stack 1, for example over approximately 20% to 50% of the axial length of the sheet stack 1.
[0022] The groove defined by the axial projections 9 of the carrier 4 and the radial projections 8 of the sheet stack 1 carrying the brackets 3 together form a shaft-hub connection.
[0023] Thus, the above rotor design forms a connection that can both transmit torque and resist axial forces.
[0024] For example, the steel sheets making up the sheet stack 1 are cut out by stamping from a ferromagnetic steel sheet (e.g., electrical steel or other soft magnetic steel). Suitable materials include silicon steel. The steel ring-shaped sheets are then stacked to form the sheet stack 1, which is subsequently connected to the carrier 4. Before the sheet stack 1 is connected to the carrier 4, the sheets of the sheet stack 1 can be connected together by one or more welds. After such pre-assembly, the sheet stack 1 is easier to handle.
[0025] Then, the sheet stack 1 is pressed axially into the carrier 4, and pairs of metal strips 3a, 3b are placed on the outer side of the sheet stack 1. The metal strips 3a, 3b are welded to each other and to the sheet stack 1. For example, the permanent magnets 2 can then be glued into the grooves on the inner side of the sheet stack 1.
[0026] The carrier 4 can be made of a non-magnetic material, for example made of an aluminum-based alloy (e.g., a casting). The carrier 4 can surround the sheet stack on its circumference (e.g., by means of the axial projections 9). In this way, the sheet stack 1 can be precisely positioned, and imbalance can be largely avoided. The carrier 4 can have a circumferential groove in which the ring-shaped sheet stack 1 is fitted.
[0027] Figure 4 A detailed view of another embodiment of the rotor is shown. This embodiment differs from the above-described embodiment only in the design of the brackets 3. As described in the above embodiment, the brackets 3 are formed by a pair of metal strips 3a, 3b, each metal strip having angled ends 5. Figure 4 A pair of metal strips before welding is shown. Thus, a gap can be seen between the narrow portions of the adjacent metal strips 3a, 3b, or a demarcation line can be seen in the case where the metal strips 3a, 3b are in contact with each other.
[0028] To manufacture the bracket 3, the metal strips 3a, 3b are then welded together while the sheet stack 1 is pressed against the bracket 4. In Figure 4 the two metal strips 3a, 3b are connected by laser welding, and in Figure 5 the two metal strips 3a, 3b are connected by tungsten inert gas welding. Figure 5 And Figure 6 both show the weld 6 that connects the two metal strips 3a, 3b of the bracket 3 together.
[0029] Figure 6 The embodiment shown in
[0030] is also different from other embodiments in that a locking ring 10 is attached to one end of the sheet stack 1 remote from the bracket 4 (e.g., the attachment of the locking ring 10 is achieved by screws 11). The locking ring 10 forms a stop for the permanent magnet 2 arranged in the groove of the sheet stack 1, thereby fixing the permanent magnet 2 to prevent axial movement.
[0030] Reference numerals
[0031] 1 Sheet stack;
[0032] 2 Permanent magnet;
[0033] 3 Bracket;
[0034] 3a Metal strip;
[0035] 3b Metal strip;
[0036] 4 Bracket;
[0037] 5 Angled end;
[0038] 6 Weld;
[0039] 7 Hub;
[0040] 8 Radial protrusion of the sheet stack;
[0041] 9 Axial protrusion of the weld;
[0042] 10 Locking ring;
[0043] 11 Screw.
Claims
1. A rotor for an outer rotor motor, comprising: A stack of steel annular sheets (1); a permanent magnet (2) fixed to the inner side of the sheet stack (1); and a bracket (4) having a hub (7) for an axle and being fastened to the stack of sheets (1); It is characterized in that A support (3) is arranged on the outer side of the sheet stack (1) and presses the sheet stack (1) against the bracket (4) in the axial direction.
2. The rotor according to claim 1, characterized in that Each of the brackets (3) is formed by two metal strips (3a, 3b), each of which has an angled end (5), and the metal strips (3a, 3b) are located adjacent to each other on the outside of the sheet stack (1), and the metal strips (3a, 3b) are welded to each other and / or to the sheet stack (1).
3. The rotor according to claim 1, characterized in that The sheet stack (1) has radial protrusions (8) on its outer side, and the support (3) is arranged on the protrusions (8).
4. The rotor according to claim 3, characterized in that The carrier (4) has grooves in which radial projections (8) of the sheet stack (1) engage.
5. The rotor according to claim 1, characterized in that The bracket (4) surrounds the stack of sheets (1) only over a portion of its axial length.
6. The rotor according to claim 1, characterized in that The sheet stack (1) has a recess, in which the permanent magnet (2) is located.