Three-section hollow rotor shaft for vehicle motor and process thereof

Abstract

The application relates to the technical field of motor rotor shafts, and provides a three-section hollow rotor shaft for a motor for vehicles and a process thereof. The three-section hollow rotor shaft for the motor for vehicles comprises a rotor shaft section, one end of the rotor shaft section is provided with a rotary variable section, and the other end of the rotor shaft section is provided with a spline section. According to the application, the shaft body is arranged into the three sections of the rotor shaft section, the rotary variable section and the spline section, the positioning rod is directly arranged in the inside of the positioning hole, the outer pressing plate can be aligned with the arc-shaped clamping groove, then the inner pressing plate can be directly pressed and assembled in the inside of the rotor shaft section by using a pressing machine, finally the spline section is arranged at the other end of the rotor shaft section by using friction welding or laser welding, the simple three-section assembly scheme can effectively reduce the weight of the motor rotor shaft, the purpose of light-weight design is achieved, and the middle section of the rotor shaft section is used for mounting motor rotor laminations, seamless steel pipes are selected, the machining allowance can be reduced, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of motor rotor shaft technology, and more specifically, to a hollow rotor shaft for automotive three-section motors and its manufacturing process. Background Technology

[0002] With the promotion and technological development of new energy vehicles, the requirements for the power torque density of vehicle drive motors are becoming increasingly stringent in order to improve vehicle performance. This increased power torque density necessitates drive motors that are small in size, lightweight, and possess excellent heat dissipation performance. Therefore, the structural design of the motor, especially the rotor shaft design, is receiving increasing attention. Currently, motor rotor shafts used in the market are divided into four types: solid shafts, hollow shafts, welded hollow shafts, and forged hollow shafts. Among them, the relatively conservative solid shaft design, although providing a higher safety factor, results in a heavier drive motor, preventing it from reaching its maximum performance. Furthermore, designing cooling channels for oil or liquid cooling of the motor rotor on a solid shaft is more difficult. During operation, the stress generated by the motor shaft is mainly concentrated on the surface, with the core bearing only minor bending stress. Therefore, the material at the core of a solid shaft is essentially redundant. Secondly, the inner hole of a hollow shaft must be a straight hole, leading to low machining efficiency, and the core material is directly removed through machining, making it difficult to reuse. This leads to material waste; furthermore, welding methods have high requirements for process control, and it is difficult to ensure the coaxiality of the two sections of the shaft. Friction welding is prone to producing a certain height of rolled edge at both ends of the shaft, affecting the flow of cooling oil; laser welding is expensive and requires high assembly precision of the shaft, otherwise welding defects are easy to occur. At the same time, due to the rapid solidification of the weld, defects such as vaporization and embrittlement are also easy to occur. Finally, radial forging and rotary forging equipment are currently mainly imported equipment, which is expensive, resulting in a higher manufacturing cost compared to traditional solid shafts. Moreover, if the feed setting is not reasonable during rotary forging, the roundness of the shaft is easily insufficient, and defects such as wrinkles and cracks appear on the surface.

[0003] To address the aforementioned issues, this application proposes a three-section hollow rotor shaft for automotive motors and its manufacturing process. Summary of the Invention

[0004] The purpose of this invention is to provide a hollow rotor shaft for a three-section motor used in automobiles and its manufacturing process, so as to solve the problems in the prior art.

[0005] The objective of this invention can be achieved through the following technical solutions: A hollow rotor shaft for a three-section automotive motor includes a rotor shaft section, a resolver section at one end of the rotor shaft section, a spline section at the other end of the rotor shaft section, a welding section at one end of the spline section for connection with the rotor shaft section, a press-fit section on the outer side of one end of the resolver section, and a protruding convex ring seat on the outer side of one end of the rotor shaft section. The convex ring seat is used to bear external forces in place of the rotor shaft section during the press-fitting of the resolver section. A convex shaft is also provided on the outer side of one end of the rotor shaft section, and a press-fit ring for mating with the convex shaft is provided on the outer side of one end of the resolver section. A reinforcing shaft for increasing the stability of the rotor shaft section is provided inside the rotor shaft section. Protruding bosses are provided on the outer sides of both ends of the reinforcing shaft. Multiple arc-shaped pads for protecting the rotor shaft section are provided at equal intervals on the outer side of the reinforcing shaft. A spring damper is provided inside the outer side of the boss for connecting with the arc-shaped pads and buffering and decomposing external forces.

[0006] Furthermore, an inner press plate for press-fitting into the cam shaft is provided on the inner side of one end of the resolver section, and a positioning rod for positioning the inner press plate is provided on the inner side of the cam shaft.

[0007] Furthermore, protruding supports are provided on the outer sides of both ends of the reinforcing shaft, and a protruding annular plate mechanism for abutting against the supports is provided on the inner side of the other end of the rotor shaft section.

[0008] Furthermore, the outer side of the support is provided with an external thread section, and the two ends of the rotor shaft section are provided with internal thread sections for engaging with the external thread section.

[0009] Furthermore, a rubber pad is provided on the outer side of the positioning rod to prevent loosening, and multiple positioning holes are equally spaced on the inner axial side of the inner pressure plate for engaging and connecting the positioning rod and the rubber pad.

[0010] Furthermore, a protruding outer pressure plate is provided on one side of the pressure ring, and an arc-shaped groove for engaging and connecting the outer pressure plate is provided on the inner side of one end of the convex shaft.

[0011] Furthermore, one end of the positioning rod is provided with a guide cone that automatically forms a guide.

[0012] Furthermore, the interior of the reinforcing shaft is provided with cooling oil channels for adding cooling oil.

[0013] Furthermore, an annular groove for mounting a spring buffer is provided on the outer side of the protrusion.

[0014] A design process for a three-section hollow rotor shaft for automotive motors, comprising a rotor shaft section, a resolver section, and a spline section, is detailed below: S1. Based on the shaft structure, the shaft body is first divided into three sections: the resolver section for mounting the rotary transformer, the rotor shaft section for mounting the rotor laminations, and the spline section for outputting torque. S2. Next, a stress analysis is performed on the shaft. The load on the motor shaft consists of the transmitted torque, the unilateral magnetic pull generated by the rotor laminations, and the rotor's own weight. The areas of the shaft subjected to torque are mainly the rotor shaft section where the rotor laminations are installed and the spline section. Through finite element analysis and experimental testing, under the action of torque, except for small stress concentrations at abrupt changes in the shaft's shape, the area of ​​maximum stress appears at the transition between the spline section and the rotor shaft section. The resolver section of the shaft is only used to install the resolver. The resolver is used to measure the position, speed, and direction of rotation of the drive motor rotor and provides this information to the motor controller for closed-loop motor control. The resolver section is basically unaffected by the load. S3. The connection between the resolver section and the rotor shaft section adopts a simple press-fit process. Since the resolver section is almost unaffected by load, the dimensional tolerance of the press-fit can be designed and checked based on a torque of 10-20 Nm, preferably 10 Nm. Because the interference fit is generally below 10 micrometers, the requirements for the press-fit equipment are not high, and assembly can be carried out at room temperature. Similarly, to save material costs, the resolver section can use a low-cost material with good rigidity but moderate strength. S4. The spline section and the rotor shaft section are connected by welding. Friction welding or laser welding can be used. Friction welding is slightly cheaper, and inertial friction welding is preferred. The height of the rolled edge should be controlled. S5. Seamless steel pipes with appropriate wall thickness and outer diameter can be directly selected for the rotor shaft section. The wall thickness is usually 6-12mm, preferably 6-8mm. Selecting seamless steel pipes reduces the amount of machining on the shaft, ensuring that materials are not wasted, saving costs, and achieving rotor weight reduction in a reasonable and effective manner.

[0015] The beneficial effects of this invention are: 1. This invention, by setting the shaft body into three sections—rotor shaft section, resolver section, and spline section—allows the positioning rod to be directly inserted into the positioning hole to align the outer press plate with the arc-shaped slot. Then, the inner press plate can be directly pressed into the inside of the rotor shaft section using a press-fitting machine. Finally, the spline section is attached to the other end of the rotor shaft section using friction welding or laser welding. This simple three-section assembly scheme can effectively reduce the weight of the motor rotor shaft, achieving the purpose of lightweight design. Furthermore, the middle section of the rotor shaft section is used to install the motor rotor laminations, and the use of seamless steel pipe can reduce machining allowance and lower costs. 2. This invention, by machining internal thread sections at both ends of the rotor shaft section, allows the reinforcing shaft to be directly pushed in and driven to screw the external thread section into the internal thread section. This enables the support to abut against the cross-section of the inwardly protruding part at the other end of the rotor shaft section, forming a limit. At this point, the external force can be buffered and decomposed directly through the arc-shaped pad and spring buffer, preventing the hollow part of the rotor shaft section from being subjected to large loads and deforming. This effectively ensures the long-term stable operation of the rotor shaft section. At the same time, it is simple to install and can be quickly inspected and replaced. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention; Figure 2 for Figure 1 A schematic diagram of the internal structure of the rotor shaft in the image; Figure 3 for Figure 1 A schematic diagram of the disassembled structure of the resolver section and rotor shaft in the rotor; Figure 4 for Figure 3 A partially enlarged structural diagram of part A in the diagram; Figure 5 for Figure 2 A schematic diagram of the outer part of the reinforcing shaft in the middle; Figure 6 for Figure 1 A schematic diagram of the connection between the arc-shaped pad and the support. The attached diagram lists the components represented by each number as follows: In the diagram: 1. Rotor shaft section; 2. Resolver section; 3. Spline section; 4. Welded section; 5. Press-fit section; 6. convex ring seat; 7. convex shaft; 8. Press-fit ring; 9. Reinforcing shaft; 10. Cooling oil passage; 11. convex seat; 12. Arc-shaped pad; 13. Spring damper; 14. Inner press-fit plate; 15. Positioning rod; 16. Support; 17. External thread section; 18. Internal thread section; 19. Rubber pad; 20. Positioning hole; 21. External press-fit plate; 22. Arc-shaped groove; 23. Guide cone; 24. Ring groove. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0019] Please refer to the details. Figure 1 , 2 And 6: A hollow rotor shaft for a three-section automotive motor, comprising a rotor shaft section 1, a resolver section 2 at one end of the rotor shaft section 1, a spline section 3 at the other end of the rotor shaft section 1, a welding section 4 at one end of the spline section 3 for connection with the rotor shaft section 1, a press-fit section 5 on the outer side of one end of the resolver section 2, a protruding convex ring seat 6 on the outer side of one end of the rotor shaft section 1, the convex ring seat 6 being used to bear external force in place of the rotor shaft section 1 during press-fitting of the resolver section 2, a convex shaft 7 on the outer side of one end of the rotor shaft section 1, and a press-fit ring 8 on the outer side of one end of the resolver section 2 for mating with the convex shaft 7. The sub-shaft segment 1 is internally provided with a reinforcing shaft 9 to increase the stability of the rotor shaft segment 1. The outer sides of both ends of the reinforcing shaft 9 are provided with protruding bosses 11. Multiple arc-shaped pads 12 are provided at equal intervals on the outer side of the reinforcing shaft 9 to form protection for the rotor shaft segment 1. The inner side of the bosses 11 is provided with spring buffers 13 for connecting with the arc-shaped pads 12 and buffering and decomposing external forces. The bosses 11 are provided at equal intervals on the outer side of the reinforcing shaft 9. The reinforcing shaft 9 can be set to different lengths according to the length requirements of the rotor shaft segment 1 to adapt to the force on different positions of the rotor shaft segment 1 and protect it.

[0020] Please continue reading. Figure 2 And 3: An inner pressing plate 14 for pressing into the inside of the cam shaft 7 is provided on the inner side of one end of the resolver section 2. A positioning rod 15 for positioning the inner pressing plate 14 is provided on the inner side of the cam shaft 7. The length of the positioning rod 15 is slightly longer than that of the cam shaft 7. The resolver section 2 can be conveniently adjusted to a suitable angle through the positioning rod 15 for subsequent pressing process.

[0021] Please continue reading. Figure 2 And 5: The outer sides of both ends of the reinforcing shaft 9 are provided with protruding supports 16, and the inner side of the other end of the rotor shaft section 1 is provided with a protruding annular plate mechanism for abutting the supports 16. After the resolver section 2 is press-fitted, the inner press plate 14 at the end of the supports 16 abuts the supports 16 located at the other end of the reinforcing shaft 9.

[0022] Please continue reading. Figure 2 , 3And 5: The outer side of the support 16 is provided with an external thread section 17, and the two ends of the rotor shaft section 1 are provided with internal thread sections 18 for the external thread section 17 to be screwed together. The adjacent external thread section 17 and internal thread section 18 have the same thread data.

[0023] Please continue reading. Figure 3 And 4: The outer side of the positioning rod 15 is provided with a rubber pad 19 to prevent loosening. The inner pressure plate 14 has multiple positioning holes 20 at equal intervals in the axial direction for the positioning rod 15 and the rubber pad 19 to engage and connect. The rubber pad 19 is used to prevent the rotation section 2 from shaking during the pressing process and affecting the pressing quality.

[0024] Please continue reading. Figure 3 And 4: A protruding outer pressure plate 21 is provided on one side of the pressure ring 8, and an arc-shaped groove 22 for engaging and connecting the outer pressure plate 21 is provided on the inner side of one end of the convex shaft 7. The outer pressure plate 21 is used to increase the connection stability of the pressure process.

[0025] Please continue reading. Figure 4 One end of the positioning rod 15 is provided with a guide cone 23 that automatically forms a guide. When the guide cone 23 abuts against the wall of the positioning hole 20, it automatically deflects to form a coaxial state.

[0026] Please continue reading. Figure 3 And 5: The interior of the reinforcing shaft 9 is provided with a cooling oil passage 10 for adding cooling oil. The cooling oil passage 10 can be equipped with a liquid delivery pipe or other mechanism according to the usage requirements.

[0027] Please continue reading. Figure 6 The outer side of the boss 11 is provided with an annular groove 24 for installing the spring buffer 13. The spring buffer 13 is arranged circumferentially at equal intervals inside the annular groove 24.

[0028] Please continue reading. Figure 1-4 A design process for a hollow rotor shaft of a three-section automotive motor, comprising rotor shaft section 1, resolver section 2, and spline section 3, is detailed below: S1. Based on the shaft structure, the shaft body is first divided into three sections: the resolver section 2, which houses the resolver; the rotor shaft section 1, which houses the rotor laminations; and the spline section 3, which outputs torque. S2. Next, a stress analysis is performed on the shaft. The load on the motor shaft is the transmitted torque, the unilateral magnetic pull generated by the rotor laminations, and the rotor's own weight. The areas of the shaft subjected to torque are mainly the rotor shaft section 1 and spline section 3 where the rotor laminations are installed. Through finite element analysis and experimental testing, under the action of torque, except for small stress concentrations at the abrupt changes in the shaft's shape, the area of ​​maximum stress appears at the transition between spline section 3 and rotor shaft section 1. The resolver section 2 of the shaft is only used to install the resolver. The resolver is used to measure the position, speed, and direction of rotation of the drive motor rotor and provides this information to the motor controller for closed-loop motor control. The resolver section 2 is basically unaffected by the load. S3. The connection between resolver section 2 and rotor shaft section 1 adopts a simple press-fit process. Since resolver section 2 is almost unloaded, the dimensional tolerance of the press-fit can be designed and checked based on a torque of 10-20 Nm, preferably 10 Nm. Since the interference fit is generally below 10 micrometers, the requirements for the press-fit equipment are not high, and assembly can be carried out at room temperature. Similarly, to save material costs, resolver section 2 can use a low-cost material with good rigidity but moderate strength. S4. The spline segment 3 and the rotor shaft segment 1 are connected by welding. Friction welding or laser welding can be used. Friction welding is slightly cheaper, and inertial friction welding is preferred to control the height of the rolled edge. S5. The rotor shaft section 1 can be made of seamless steel pipe with appropriate wall thickness and outer diameter. The wall thickness is usually 6-12mm, preferably 6-8mm. Using seamless steel pipe reduces the amount of machining on the shaft, ensures that materials are not wasted, saves costs, and can reasonably and effectively achieve the lightweighting of the rotor. The working principle of this invention is as follows:

[0029] This invention, by configuring the shaft into three segments—rotor shaft segment 1, resolver segment 2, and spline segment 3—directly inserts the positioning rod 15, located on the inner side of one end of rotor shaft segment 1, into the positioning hole 20 located on the outer side of the inner press-fit plate 14 at one end of resolver segment 2. This aligns the outer press-fit plate 21, located on the outer side of the press-fit ring 8, with the arc-shaped groove 22 on the inner side of one end of rotor shaft segment 1. Then, using a press-fitting machine, the inner press-fit plate 14 can be directly press-fitted into the rotor shaft segment 1. During this press-fitting process, the convex shaft 7, located on the outer side of one end of rotor shaft segment 1, can be mounted on the upper end of the press-fitting machine's base to prevent excessive external force from damaging the rotor shaft segment 1. Finally, the spline segment 3 is attached to the other end of rotor shaft segment 1 using friction welding or laser welding. This simple three-segment assembly scheme effectively reduces the weight of the motor rotor shaft, achieving lightweight design. The purpose of this invention is to reduce machining allowance and lower costs by using seamless steel pipes in the middle section of rotor shaft segment 1, which is used to install motor rotor laminations. After machining internal thread segments 18 inside both ends of rotor shaft segment 1, the reinforcing shaft 9 can be directly pushed in to drive the external thread segments 17 located outside the supports 16 at both ends of the reinforcing shaft 9 to be screwed into the internal thread segments 18. This allows the supports 16 to abut against the cross-section of the inwardly protruding part at the other end of rotor shaft segment 1 to form a limit. At this time, the external force can be buffered and decomposed directly by the arc-shaped pads 12 on the outside of the reinforcing shaft 9 and the spring buffers 13 inside the annular groove 24 on the outside of the boss 11, preventing the hollow part of rotor shaft segment 1 from being deformed by large loads. This effectively ensures the long-term stable operation of rotor shaft segment 1, while its installation is simple and can be quickly inspected and replaced.

[0030] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hollow rotor shaft for a three-section motor used in vehicles, comprising a rotor shaft section (1), characterized in that: One end of the rotor shaft section (1) is provided with a resolver section (2), and the other end of the rotor shaft section (1) is provided with a spline section (3). One end of the spline section (3) is provided with a welding section (4) for connecting with the rotor shaft section (1). One end of the resolver section (2) is provided with a press-fit section (5). One end of the rotor shaft section (1) is provided with a protruding convex ring seat (6). The convex ring seat (6) is used to replace the rotor shaft section (1) in bearing external force during the press-fitting of the resolver section (2). One end of the rotor shaft section (1) is also provided with a convex shaft (7). A press-fit ring (8) for docking with a cam shaft (7) is provided on the outer side of one end of the rotor section (2). A reinforcing shaft (9) for increasing the stability of the rotor shaft section (1) is provided inside the rotor shaft section (1). A protruding boss (11) is provided on the outer side of both ends of the reinforcing shaft (9). A number of arc-shaped pads (12) for forming protection for the rotor shaft section (1) are provided at equal intervals on the outer side of the reinforcing shaft (9). A spring buffer (13) for connecting with the arc-shaped pad (12) and buffering and decomposing external forces is provided inside the outer side of the boss (11). The inner side of one end of the resolver section (2) is provided with an inner press plate (14) for press-fitting into the inside of the cam shaft (7), and the inner side of the cam shaft (7) is provided with a positioning rod (15) for positioning the inner press plate (14). The outer sides of both ends of the reinforcing shaft (9) are provided with protruding supports (16), and the inner side of the other end of the rotor shaft section (1) is provided with a protruding annular plate mechanism for abutting against the supports (16). The support (16) is provided with an external thread section (17) on its outer side, and the rotor shaft section (1) is provided with internal thread sections (18) for screwing the external thread section (17) into place at both ends. The outer side of the positioning rod (15) is provided with a rubber pad (19) to prevent loosening, and the inner pressure plate (14) has multiple positioning holes (20) at equal intervals in the inner axial direction for the positioning rod (15) and the rubber pad (19) to engage and connect. The press ring (8) has a protruding outer press plate (21) on one side, and an arc-shaped groove (22) for engaging the outer press plate (21) is provided on the inner side of one end of the convex shaft (7).

2. The hollow rotor shaft for a three-section motor in an automotive application according to claim 1, characterized in that: One end of the positioning rod (15) is provided with a guide cone (23) that automatically forms a guide.

3. The hollow rotor shaft for a three-section motor in an automotive application according to claim 1, characterized in that: The reinforcing shaft (9) has a cooling oil passage (10) inside for adding cooling oil.

4. The hollow rotor shaft for a three-section motor in an automotive application according to claim 1, characterized in that: The outer side of the boss (11) is provided with an annular groove (24) for installing the spring buffer (13).

5. A process for a hollow rotor shaft for a three-section automotive motor, applied to the hollow rotor shaft for a three-section automotive motor as described in any one of claims 1-4, comprising a rotor shaft section (1), a resolver section (2), and a spline section (3), characterized in that: The specific design process is as follows: S1. Based on the structure of the shaft, the shaft body is first divided into three sections: the resolver section (2) for installing the rotary transformer, the rotor shaft section (1) for installing the rotor laminations, and the spline section (3) for outputting torque. S2. Next, the shaft is subjected to stress analysis. The load on the motor shaft is the torque it transmits, as well as the unilateral magnetic pull generated by the rotor laminations and the rotor's own gravity. The area of ​​the shaft subjected to torque is mainly the rotor shaft section (1) and spline section (3) where the rotor laminations are installed. Through finite element analysis and experimental testing, under the action of torque, except for small stress concentrations at the abrupt change in the shape of the shaft, the area with the greatest stress appears at the transition between the spline section (3) and the rotor shaft section (1). The resolver section (2) of the shaft is only used to install the resolver. The resolver is used to measure the position, speed and rotation direction of the drive motor rotor and provide it to the motor controller for closed-loop motor control. The resolver section (2) is not subjected to load. S3. The connection between the resolver section (2) and the rotor shaft section (1) adopts a press-fit process. The dimensional tolerance of the press-fit is designed and checked according to a torque of 10-20 Nm. The interference is less than 10 micrometers. The resolver section (2) is assembled at room temperature. The resolver section (2) is made of a low-cost material with good rigidity but average strength. S4. The welding method between the spline section (3) and the rotor shaft section (1) is friction welding or laser welding to control the height of the rolled edge; S5. Rotor shaft section (1) Select seamless steel pipe with appropriate wall thickness and outer diameter. The wall thickness is 6-12mm. Selecting seamless steel pipe reduces the amount of machining on the shaft, so as to ensure that the material is not wasted, save costs, and can reasonably and effectively achieve the lightweighting of the rotor.

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