Rotor assembly and motor

Abstract

The present invention relates to a rotor assembly, comprising: a rotor shaft (1), a rotor lamination stack (2), and a confluence device (3). The confluence device is provided with busbars (31) and confluence rings (32); the rotor lamination stack (2) is provided with through holes extending in the axial direction; each busbar (31) passes through the corresponding through hole and is fixedly connected to the confluence rings (32) disposed on the axial end sides of the rotor lamination stack (2); a transition member (33) is provided between each confluence ring (32) and the rotor lamination stack (2); the transition member (33) is provided with connecting holes (331); and the structure of each connecting hole (331) is designed such that the cross section of each busbar (31) becomes larger after passing through the connecting hole (331) during injection molding, so that the busbar (31) forms smooth transitional contact with the confluence rings (32). In addition, the present invention also relates to a motor having the rotor assembly.

Description

Rotor assembly and motor Technical Field

[0001] The present invention relates to the field of vehicle technology, and more specifically, to a motor and rotor assembly for new energy vehicles, wherein the motor is particularly an induction motor. Background Art

[0002] For four-wheel drive vehicles, an induction motor is often used on the front axle. This is not only because induction motors do not require complex decoupling structures, but also because they reduce costs. Typically, an induction motor consists of an induction stator and a cast aluminum rotor. The cast aluminum rotor consists of a shaft, rotor laminations, and a current collector. The current collector is usually designed as a rotor bracket, such as the squirrel cage bracket of a squirrel-cage rotor. It forms a closed circuit around the circuit, inducing current and forming a magnetic field corresponding to the stator coil.

[0003] DE 102009034647 A1 discloses a rotor assembly. In this rotor assembly, the busbars of a current collecting device extend through slots in the rotor lamination stack and are fixedly connected to the collecting end rings at each axial end of the rotor lamination stack. In the prior art, such current collecting devices are typically manufactured through integral casting, for example, by molding and casting directly onto the rotor lamination stack of the rotor assembly. This results in a right-angle connection between the busbars and the collecting end rings.

[0004] In new energy electric vehicles, the motors typically run at very high speeds, sometimes exceeding 18,600 rpm. Strength simulation results show that at these high speeds, stress concentration occurs at the connection points between the busbar and the slip ring. The area surrounding these stress concentration points can easily reach the material's yield point, ultimately leading to deformation and failure.

[0005] Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide an improved rotor assembly for a motor, which can adapt to higher rotation speeds and is easy to manufacture.

[0007] In order to solve the above technical problems, the present invention provides a rotor assembly for an electric motor. The rotor assembly includes a rotor shaft, a rotor lamination stack, and a collector device. The collector device is composed of a bus bar and a collector ring. The rotor lamination stack has axially extending through holes, and the bus bar passes through these through holes and is fixedly connected to the collector ring arranged on the axial end side of the rotor lamination stack. In order to achieve smooth transition contact between the bus bar and the collector ring, the rotor assembly also includes a transition piece, which is arranged between the collector ring and the rotor lamination stack. The transition piece has connecting holes corresponding to the through holes. The structure of the connecting holes is designed so that the cross-section of the bus bar becomes larger after passing through these connecting holes during the injection molding process, thereby forming a smooth transition contact with the collector ring, avoiding right-angle contact, and also avoiding stress concentration at high speeds, thereby improving the stability of the rotor assembly.

[0008] According to a preferred embodiment of the present invention, the cross-section of the busbar gradually increases within the connection hole. This connection hole structure provides a more uniform mass distribution, avoiding localized stress concentration. Furthermore, the connection hole is preferably rounded on the side facing the slip ring. This design helps reduce stress concentration, allowing the slip ring to form a rounded contact with the busbar, thereby improving the stability and reliability of the entire device. Furthermore, preferably, the connection holes correspond one-to-one with the through holes, so that all busbars can form a smooth contact with the slip ring, forming a stable structure.

[0009] According to a preferred embodiment of the present invention, the busbar and the slip ring are formed by integral injection molding. The transition piece can also be fixed together through the injection molding process. This integral injection molding structure simplifies the manufacturing process, improves the efficiency of assembly, and ensures a tight connection between the busbar, the transition piece and the slip ring, forming a smooth transition structure. It is further preferred that the melting point of the transition piece is higher than the melting point of the busbar and the slip ring. This design helps to ensure that the transition piece will not melt or be damaged during injection molding, thereby maintaining the formation of the busbar. It is further preferred that the transition piece is a steel ring. The advantage of using a steel ring as a transition piece is that it has good strength and high temperature resistance, and is low in cost. It is also preferred that the busbar and the slip ring are made of aluminum, which has a lower melting point than steel, so that it can flow stably through the connecting hole of the steel ring when the busbar is cast.

[0010] According to a preferred embodiment of the present invention, the transition piece has multiple locating pins on the side facing the rotor lamination stack. The rotor lamination stack is provided with corresponding grooves into which the locating pins fit after assembly. These locating pins prevent the transition piece from moving, thereby maintaining its position during injection molding of the busbars. Furthermore, these locating pins unite the steel ring, busbars, slip rings, and rotor laminations into a single, integrated component, effectively resisting centrifugal stress at high speeds.

[0011] In summary, the present invention provides a rotor assembly with an optimized design and structure that helps improve the performance, efficiency, and reliability of electric motors or generators. By improving the busbar assembly and adding a transition piece between the slip rings and the rotor lamination stack, the connection between the busbars and slip rings is smoother, avoiding sharp corners and meeting the requirements of high-speed motors.

[0012] In addition, the technical problem to be solved by the present invention can also be solved by an electric motor having a rotor assembly with the above-mentioned features. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The preferred embodiments of the present invention are further described below with reference to the accompanying drawings.

[0014] FIG1 shows a perspective view of a rotor assembly and some components designed according to the present invention;

[0015] FIG2 shows an axial cross-sectional view of a rotor assembly according to the prior art;

[0016] FIG3 shows an axial cross-sectional view of a rotor assembly designed according to the present invention;

[0017] FIG4 shows a perspective view of the transition piece;

[0018] FIG5 is a partial enlarged view of a flow confluence device designed according to the present invention.

[0019] Unless otherwise specified, the “axial direction”, “radial direction” and “circumferential direction” mentioned in the present invention are all relative to the rotor axis. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings. The following detailed description and the accompanying drawings are used to illustrate the principles of the present invention by way of example. The present invention is not limited to the preferred embodiments described, and the scope of the present invention is defined by the claims. The present invention will now be described in detail with reference to exemplary embodiments, some of which are illustrated in the accompanying drawings. The following description is made with reference to the accompanying drawings, and unless otherwise indicated, the same reference numerals in different drawings represent the same or similar elements. The schemes described in the following exemplary embodiments do not represent all schemes of the present invention. On the contrary, these schemes are merely examples of systems and methods of various aspects of the present invention involved in the appended claims.

[0021] Figure 1 shows a rotor assembly designed according to the present invention, comprising a rotor shaft 1, a rotor lamination stack 2, and a current collecting device 3. The current collecting device 3 comprises busbars 31 and slip rings 32. The slip rings 32 are located at both ends of the rotor lamination stack 2. The busbars 31 pass through the rotor lamination stack 2 and connect to the slip rings 32 located on both sides. Preferably, the busbars 31 and slip rings 32 form a bracket, in which the rotor lamination stack 2 is disposed, thereby forming a squirrel-cage rotor as known in the art. This squirrel-cage bracket is typically formed by direct injection molding onto the rotor lamination stack 2.

[0022] Figures 2 and 3 show axial cross-sectional views of a rotor assembly according to the prior art and according to the present invention, respectively. As shown in Figure 2, busbar 31 passes through the laminated rotor lamination stack 2 and directly contacts and securely connects to slip ring 32. The connection between busbar 31 and slip ring 32 forms a 90° angle. When the rotor assembly rotates at high speeds, stress concentration easily occurs at this angle, making it easy for busbar 31 to separate from slip ring 32.

[0023] To overcome this shortcoming, according to the present invention, a transition piece 33 is additionally provided between the busbar 31 and the slip ring 32. This transition piece 33 has a connection hole 331 through which the busbar 31 passes. The opening between the first contact surface of this connection hole 331 and the busbar 31 is smaller than the opening between the second contact surface of this hole 331 and the slip ring 32. This ensures that the connection between the transition piece 33 and the slip ring 32 does not form a sharp corner, but rather a rounded transition. This rounded transition design, based on a smooth transition structure with different sizes on both sides, minimizes stress concentration between the busbar and the slip ring.

[0024] Figure 4 shows the first and second contact surfaces of the transition piece 33. In this embodiment, the transition piece 33 is designed as a steel ring, and the collector assembly 3 is designed to be made of aluminum. Since the collector assembly 3 is typically formed by injection molding, the melting point of the transition piece 33 needs to be higher than that of the busbars and slip rings. To ensure more accurate positioning of the transition piece 33 during injection molding, multiple locating pins 332 are provided on the transition piece 33, and locating grooves are provided at corresponding locations on the rotor lamination stack 2. The locating pins 332 are first used to accurately position and secure the transition piece 33, and then the collector assembly 3 is formed by injection molding. The locating pins 332 integrate the steel ring, busbars 31, slip rings 32, and rotor lamination stack 2 into a single unit, jointly resisting centrifugal stress at high speeds. During rotation, the stress of the slip ring 32 is transferred to the steel ring 33, while the centrifugal force of the steel ring 33 is transferred to the rotor lamination stack 2.

[0025] As shown in Figure 4, the steel ring 33 is designed to match the rotor lamination stack 2, with the same number of slots but different sizes. As shown in the left image of Figure 4, the slots of the steel ring 33 on the side closest to the rotor lamination stack 2 (i.e., the first contact surface) maintain the same size as the slots in the rotor laminations. On the other side (the second contact surface, shown in the right image of Figure 4), the slots gradually increase in size through a rounded transition. This rounded transition causes the busbar to become larger before contact with the slip ring, thereby increasing the diameter and strength of the cast busbar at the end of the rotor lamination stack 2.

[0026] Figure 5 shows an enlarged partial view of the busbar assembly 3 designed according to the present invention. With the addition of steel rings 33, the cast busbar 31 becomes larger due to the rounded transition structure at the end of the rotor lamination stack 2, increasing the contact area and transition angle with the slip ring 32. The original sharp transition between busbar 31 and slip ring 32 is replaced by this rounded transition structure, thereby increasing the strength and structural stability of the entire rotor.

[0027] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the configurations and methods of the above-described embodiments. On the contrary, the present invention is intended to cover various modifications and equivalent configurations. In addition, although the various elements and method steps of the disclosed invention are shown in various exemplary combinations and configurations, other combinations including more or fewer elements or methods also fall within the scope of the present invention.

[0028] LIST OF REFERENCE NUMERALS 1 Rotor shaft 2 Rotor lamination stack 3 Busbar 31 Busbar 32 Slip ring 33 Transition piece 331 Connecting hole 332 Positioning pin

Claims

1. A rotor assembly, comprising: A rotor shaft (1), a rotor lamination stack (2), and a current collecting device (3), wherein the current collecting device has current collecting bars (31) and a current collecting ring (32), the rotor lamination stack (2) has an axially extending through hole, the current collecting bars (31) pass through the through hole and are fixedly connected to the current collecting ring (32) provided on the axial end side of the rotor lamination stack (2), wherein a transition member (33) is provided between the current collecting ring (32) and the rotor lamination stack (2), the transition member (33) has a connection hole (331), and the structure of the connection hole (331) is designed such that the cross-section of the current collecting bar (31) becomes larger after passing through the connection hole (331) during injection molding, so that the current collecting bar (31) forms a smooth transition contact with the current collecting ring (32).

2. The rotor assembly according to claim 1, wherein, The cross-section of the current collecting bar (31) gradually becomes larger in the connection hole (331).

3. The rotor assembly according to claim 1, wherein, The connection hole (331) has a chamfer on the side facing the current collecting ring (32).

4. The rotor assembly according to claim 1, characterized in that, The connection holes (331) correspond one-to-one to the through holes.

5. The rotor assembly according to any one of claims 1 to 4, characterized in that, The current collecting bar (31) and the current collecting ring (32) are integrally injection molded.

6. The rotor assembly according to claim 5, characterized in that, The melting point of the transition member (33) is higher than the melting points of the current collecting bar (31) and the current collecting ring (32).

7. The rotor assembly according to claim 6, characterized in that, The transition member (33) is a steel ring.

8. The rotor assembly according to claim 7, wherein The current collecting bar (31) and the current collecting ring (32) are made of aluminum.

9. The rotor assembly according to claim 5, wherein The transition member (33) has a plurality of positioning pins (332) on the side facing the rotor lamination stack (2).

10. A motor, characterized in that, The motor has a rotor assembly according to any one of claims 1 to 9.

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