Electric drive axle motor and gearbox spline connection impact resistance buffer structure

Abstract

The application discloses a kind of electric drive bridge motor and gearbox spline connection anti-impact buffer structure, including the inner layer spline sleeve of one end opening, the inner surface of inner layer spline sleeve is equipped with the inner spline of the outer spline of the cooperation of gearbox input shaft, the outer surface of inner layer spline sleeve is equipped with the radial extension of convex strip, and convex strip and the axial concave groove of the inner surface of motor output shaft are adapted;It also includes the outer layer support sleeve of one end opening, the side wall of outer layer support sleeve is equipped with the strip-shaped gap corresponding to convex strip, and strip-shaped gap penetrates the opening of outer layer support sleeve;It also includes the middle layer composite buffer layer filled between inner layer spline sleeve and outer layer support sleeve, and the inside of middle layer composite buffer layer is distributed with multiple elastic members, and the expansion direction of all elastic members is consistent with the radial direction of inner layer spline sleeve.The buffer performance of the application is excellent and the structure is stable, can significantly reduce the radial impact peak, and the spring as keel prevents rubber fatigue damage, greatly improves the service life.

Description

Technical Field

[0001] This invention belongs to the technical field of electric drive axle transmission for new energy commercial vehicles. Specifically, it relates to an anti-impact buffer structure for the spline connection between the electric drive axle motor and the transmission. Background Technology

[0002] In the field of new energy electric drive axles, to improve the compactness and efficiency of the transmission system, the motor and single-stage reduction gearbox are generally arranged coaxially. The motor output shaft and the gearbox input shaft are often connected by a direct mating fit of internal and external splines to achieve torque transmission. To meet assembly process requirements and accommodate component manufacturing tolerances, this splined connection must have a certain amount of tooth flank clearance.

[0003] During normal vehicle operation, the splined joint is supported and transmits drive torque only on one side of the tooth surface. However, when the vehicle brakes or decelerates rapidly, the motor's operating state instantly switches from drive to regenerative braking, causing a 180° reversal in torque direction. The splined joint's supporting tooth surface then switches from one side to the other. During this reversal process, transient impacts occur between the meshing teeth due to tooth backlash. This impact manifests circumferentially as tooth-to-tooth surface collisions, the intensity of which can be effectively mitigated by existing technologies such as optimizing tooth surface heat treatment processes, improving lubrication conditions, or applying anti-friction coatings; it is a conventional and controllable problem in this field. However, the reversal impact is accompanied by a significant radial impact component. This radial impact originates from the instantaneous change in the normal force of the tooth surface during the backlash reversal of the splined joint. It exhibits periodic and alternating characteristics and is directly transmitted to the support bearing at the motor output shaft end via the gearbox input shaft and the splined joint, forming a continuous alternating radial load. Under long-term action, this load is prone to induce early failure modes such as bearing raceway fatigue spalling and cage fracture, and causes unilateral radial wear on the spline tooth surface, which in turn seriously weakens the service reliability and service life of the electric drive bridge. Moreover, there is a lack of simple and effective structural solutions to this radial impact problem in the field.

[0004] Furthermore, in existing structures, the internal splines are typically machined directly onto the motor output shaft. If the splines fail due to wear or impact damage, the entire motor shaft must be replaced, resulting in high maintenance costs and long downtime. Additionally, because the splines and shaft are integral rigid structures, there is no way to install a buffer medium or energy-absorbing layer between them, leaving no effective path for dissipating impact energy and further exacerbating the risk of damage to the bearings and splines themselves.

[0005] To address the above issues, some technologies have attempted to add buffer structures inside or outside the spline joint, but due to practical engineering constraints, they generally still have the following shortcomings: The insufficient bonding strength between the buffer layer and the metal substrate, poor reliability of anti-rotation positioning, and the contradiction between buffer performance and the rigidity requirements of the transmission system, coupled with the fact that most solutions are not suitable for the assembly structure of independently replaceable spline sleeves, make it difficult to balance maintainability and buffering effectiveness. Therefore, there is an urgent need for a new connection solution that can effectively absorb commutation radial impacts while possessing good structural rigidity and replaceability, in order to fundamentally improve the long-term service performance of the electric drive bridge spline pair. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an anti-impact buffer structure for the spline connection between an electric drive axle motor and a gearbox. The structure includes an inner spline sleeve with one open end, the inner surface of which has an inner spline that mates with the outer spline of the gearbox input shaft, and the outer surface of which has a radially extending ridge that matches an axial concave groove on the inner surface of the motor output shaft. It also includes an outer support sleeve with one open end, the sidewall of which has a strip-shaped notch corresponding to the ridge, the notch penetrating the opening. Finally, it includes a middle composite buffer layer filled between the inner spline sleeve and the outer support sleeve, with multiple elastic elements distributed within the middle composite buffer layer, all of which extend in the same direction as the radial direction of the inner spline sleeve.

[0007] The preferred embodiment of this invention is as follows: the convex strip, the axial concave groove, and the strip-shaped notch form a set of circumferential positioning structures, and four sets of circumferential positioning structures are provided, which are evenly distributed along the circumference. The design of the four sets of circumferential positioning structures has a dual function: first, it can reliably transmit the working torque and prevent the middle composite buffer layer from shearing slippage or circumferential torsion under load; second, the axial engagement of the strip-shaped notch and the convex strip allows for a slight radial displacement between the inner and outer layers (compressing the buffer layer), but restricts their relative rotation, thereby ensuring that the elastic element is always subjected to force along the predetermined radial direction and extending the service life of the buffer structure.

[0008] A preferred embodiment of this invention is as follows: two rows of elastic elements are provided between every two adjacent sets of circumferential positioning structures, and the two rows of elastic elements are evenly distributed along the axial direction of the middle composite buffer layer. Specifically, the central angle between every two adjacent rows of elastic elements is 30°. The arrangement of two rows of elastic elements between adjacent sets of circumferential positioning structures, with the included angle between the central angles of adjacent rows of elastic elements limited to 30°, results in a denser and more uniform distribution of buffer support points in the circumferential direction. This not only avoids local stress concentration but also ensures that the buffer layer receives uniform support reaction force regardless of the direction of torque reversal, further improving the stability of the structure under complex alternating working conditions.

[0009] A preferred embodiment of the present invention is as follows: the outer surface of the outer support sleeve is provided with an annular groove near the opening, and the annular groove is provided with a matching retaining ring. One end of the strip-shaped notch is open to allow the protruding strip to slide in, and the other end is closed for positioning. The retaining ring at the open end cooperates with the annular groove to achieve reverse locking, thereby firmly locking the inner spline sleeve and the inner spline sleeve together.

[0010] The preferred embodiment of this invention is as follows: the middle composite buffer layer is fixedly bonded between the inner spline sleeve and the outer support sleeve. The middle composite buffer layer is fixedly bonded between the inner spline sleeve and the outer support sleeve through vulcanization or strong bonding processes. This interference fit eliminates the assembly gap between the sleeves, improves the coaxiality of the overall structure, and also enhances the bonding force between the buffer layer and the metal substrate, effectively avoiding the risk of buffer layer peeling due to centrifugal force under high-speed rotation conditions. Furthermore, both ends of all elastic elements are exposed on the outer and inner surfaces of the middle composite buffer layer, allowing the elastic elements to directly contact the inner or outer metal sleeve when subjected to large radial impact loads, forming a composite buffer mechanism of "rubber / polyurethane soft buffer + spring steel hard limit." This not only prevents the middle composite buffer layer from over-shear fracture under extreme conditions but also endows the structure with certain variable stiffness characteristics (soft under small torque, hard under large impact), further optimizing NVH (noise, vibration, and harshness) performance. Simultaneously, after absorbing the impact, the radial displacement tendency disappears, and the spring, relying on its elastic restoring force, pushes the inner spline sleeve back to the center position. The middle composite buffer layer assists in reset and reduces oscillation. Throughout the process, the anti-rotation design of the convex strip and axial concave groove ensures that no circumferential relative rotation occurs.

[0011] The beneficial effects of this invention are as follows: 1. Excellent cushioning performance and stable structure. The spring and rubber composite of the middle layer work together to significantly reduce the radial impact peak, and the spring acts as a keel to prevent rubber fatigue failure, greatly improving service life.

[0012] 2. Reliable anti-rotation positioning and good replaceability. The cuboid protrusion, the strip notch, and the axial concave groove of the motor form a double circumferential locking, which, together with the interference fit and the multiple fixation of the retaining ring, ensures absolute synchronization; the independent part design allows for direct replacement after wear, greatly reducing maintenance costs.

[0013] 3. High space utilization and simple assembly. The radial arrangement of the springs does not increase the axial dimension, and the open slot design allows the protrusion to slide in to complete the assembly. No complex tooling is required, and the cold and hot pressing process is mature and reliable.

[0014] 4. Interface compatibility and unaffected lubrication. The internal spline parameters are consistent with the original design, and the gearbox input shaft requires no modification; the spring clearance and the tiny gaps between the rubber and metal allow coolant to pass through normally, ensuring lubrication and heat dissipation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application 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 recorded in this application. 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 anti-impact buffer structure for the spline connection between the electric drive axle motor and the gearbox in this invention. Figure 2 This is a schematic diagram of the anti-shock buffer structure for the spline connection between the electric drive axle motor and the gearbox in this invention, as well as the assembled output shaft and input shaft. Figure 3 for Figure 2 The split diagram.

[0017] Figure label: 1. Output shaft; 101. Axial concave groove; 2. Input shaft; 201. External spline; 3. Inner spline sleeve; 301. Internal spline; 302. Raised bar; 4. Middle layer composite buffer layer; 401. Elastic component; 5. Outer support sleeve; 501. Strip notch; 502. Annular groove; 503. Snap ring. Detailed Implementation

[0018] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution, its implementation process, and principles will be further explained below with reference to the accompanying drawings and specific implementation examples in the embodiments of this application.

[0019] like Figure 1 As shown, this embodiment provides an anti-impact buffer structure for the spline connection between the electric drive axle motor and the gearbox, including an inner spline sleeve 3, a middle composite buffer layer 4 and an outer support sleeve 5. One end of the outer support sleeve 5 and one end of the inner spline sleeve 3 are provided with openings, and both are made of steel. The middle composite buffer layer 4 is composed of a rubber filler and an elastic element 401 embedded therein.

[0020] The manufacturing processes for the inner spline sleeve 3, the middle composite buffer layer 4, and the outer support sleeve 5 are as follows: like Figure 1 and Figure 3As shown, the rubber filler of the middle composite buffer layer 4 fills the entire annular space between the inner spline sleeve 3 and the outer support sleeve 5, and is bonded to the inner spline sleeve 3 and the outer support sleeve 5 through a vulcanization process, forming a strong bond that does not separate. The middle composite buffer layer 4 contains multiple elastic elements 401. In this embodiment, the elastic elements 401 are springs, and the extension and contraction directions of all springs are consistent with the radial direction of the inner spline sleeve 3. Both ends of all elastic elements 401 are exposed on the outer and inner surfaces of the middle composite buffer layer 4, allowing the elastic elements 401 to directly contact the inner or outer metal sleeve when subjected to large radial impact loads.

[0021] The specific structure of the inner spline sleeve 3 is as follows: like Figure 1 and Figure 3 As shown, the inner surface of the inner spline sleeve 3 is provided with an inner spline 301 that mates with the outer spline 201 of the gearbox input shaft 2, without changing the existing interface size of the outer spline 201 of the gearbox input shaft 2, and the two are compatible. The outer surface of the inner spline sleeve 3 is provided with radially extending ridges 302, both ends of which extend axially and are close to the ends of the inner spline sleeve 3. Sufficiently long ridges 302 can withstand shear stress. The inner surface of the motor output shaft 1 is provided with axial concave grooves 101 corresponding to the ridges 302. There are four ridges 302, which are evenly distributed along the circumference. There are also four corresponding axial concave grooves 101. All the ridges 302 slide into the axial concave grooves 101 one by one, forming a circumferential anti-rotation locking structure.

[0022] The specific structure of the outer support sleeve 5 is as follows: like Figure 1 and Figure 3 As shown, the side wall of the outer support sleeve 5 is provided with a strip-shaped notch 501 corresponding to the protrusion 302. The strip-shaped notch 501 penetrates the opening of the outer support sleeve 5. After the protrusion 302 passes through the strip-shaped notch 501, it slides into the axial concave groove 101 of the motor output shaft 1. In order to maintain the locked state of the inner spline sleeve 3 and the outer support sleeve 5, an annular groove 502 is provided on the outer surface of the outer support sleeve 5 near the opening, and the annular groove 502 is provided with a matching retaining ring 503. One end of the strip-shaped notch 501 is open to allow the protrusion 302 to slide in, and the other end is closed for positioning. The retaining ring 503 at the open end cooperates with the annular groove 502 to achieve reverse locking, thereby firmly locking the inner spline sleeve 3 and the outer support sleeve 5 together.

[0023] The assembly process of the shock-resistant buffer structure and the motor output shaft 1 in this embodiment is as follows: like Figure 2As shown, a hot-cold assembly process is used. The motor output shaft 1 is heated to expand its inner hole, while the impact-resistant buffer structure is cooled to shrink its outer diameter. The impact-resistant buffer structure is then installed into the inner hole of the motor output shaft 1, so that the four protrusions 302 slide into the four axial concave grooves 101 one-to-one. After the temperature recovers, the interference fit between the outer support sleeve 5 and the motor output shaft 1 is formed. Finally, the retaining ring 503 is installed in the annular groove 502 to complete the axial locking.

[0024] like Figure 1 and Figure 3 As shown, the connection between the shock-absorbing structure and the gearbox input shaft 2 is the same as the existing connection method, using the direct mating of inner and outer splines 201 to achieve torque transmission. Although radial impact force still exists between the inner and outer splines 201, this radial impact force is transmitted to the middle composite buffer layer 4 through the radial displacement of the inner spline sleeve 3, where it is absorbed and converted into internal energy. The inner spline sleeve 3 returns to the center position through the elastic restoring force of the spring, while the rubber assists in resetting and reducing oscillation. Throughout the process, the anti-rotation design of the boss and groove ensures that no circumferential relative rotation occurs, while supporting the slight radial offset of the inner spline sleeve. To improve the centering restoring force, the springs in this embodiment are distributed as follows: Two rows of elastic elements 401 are provided between each pair of adjacent circumferential positioning structures, and the two rows of elastic elements 401 are evenly distributed along the axial direction of the middle composite buffer layer 4. Each row of elastic elements 401 includes five springs, which are equally spaced on a straight line. The central angle between each pair of adjacent rows of elastic elements 401 is 30°. The arrangement of two rows of elastic elements 401 between each pair of adjacent circumferential positioning structures, and the limitation of the included angle of the central angle between adjacent rows of elastic elements 401 to 30°, makes the buffer support points in the circumferential direction more dense and uniform. The restoring force of all springs points towards the central axis. No matter which direction the inner spline sleeve 3 is offset, the restoring force of the springs pointing towards the central axis always returns the inner spline sleeve 3 to the center of rotation, maintaining concentricity.

[0025] This embodiment features a middle composite buffer layer 4 with radially distributed elastic elements 401 embedded within it. When the motor switches from drive to regenerative braking (torque reversal), the viscoelastic deformation of the middle composite buffer layer 4 and the radial compressive deformation of the elastic elements 401 effectively absorb and dissipate the radial impact component caused by tooth backlash. This structure successfully blocks the direct transmission of commutation impact force to the motor output shaft 1 support bearing, transforming the originally destructive alternating radial load into the internal strain energy of the buffer layer. This fundamentally solves problems in existing technologies such as bearing raceway fatigue spalling, cage fracture, and unilateral wear of spline teeth caused by radial impact, significantly improving the service life and reliability of the electric drive axle.

[0026] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A shock-resistant buffer structure for the spline connection between an electric drive axle motor and a gearbox, characterized in that: It includes an inner spline sleeve with one end open, the inner surface of the inner spline sleeve is provided with an inner spline that mates with the outer spline of the gearbox input shaft, and the outer surface of the inner spline sleeve is provided with a radially extending ridge, which is adapted to the axial concave groove on the inner surface of the motor output shaft. It also includes an outer support sleeve with one end open, and the side wall of the outer support sleeve is provided with a strip-shaped notch corresponding to the protrusion, the strip-shaped notch penetrating the opening of the outer support sleeve; It also includes a middle composite buffer layer filled between the inner spline sleeve and the outer support sleeve. Multiple elastic elements are distributed inside the middle composite buffer layer, and the expansion and contraction directions of all elastic elements are consistent with the radial direction of the inner spline sleeve.

2. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 1, characterized in that: The convex strip, axial concave groove and strip notch form a set of circumferential positioning structures. There are four sets of circumferential positioning structures, which are evenly distributed along the circumference.

3. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 2, characterized in that: Two rows of elastic elements are provided between each pair of adjacent circumferential positioning structures, and the two rows of elastic elements are evenly distributed along the axial direction of the middle composite buffer layer.

4. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 3, characterized in that: The central angle between each pair of adjacent rows of elastic elements is 30°.

5. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 1, characterized in that: The outer surface of the outer support sleeve is provided with an annular groove near the opening, and the annular groove is provided with a matching retaining ring.

6. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 1, characterized in that: The middle composite buffer layer is bonded and fixed between the inner spline sleeve and the outer support sleeve.

7. The shock-resistant buffer structure for the spline connection between the electric drive axle motor and the gearbox according to claim 1, characterized in that: Both ends of all elastic elements are exposed on the outer and inner surfaces of the middle composite buffer layer.

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