Splined Coupling With Two-Section Tooth Profile for Backlash-Free Torque
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Solution Overview
Problem
Existing fitting connections in vehicle construction, such as those between the drive shaft and wheel bearing, experience noise issues due to torque-induced slipping, which worsens with higher wheel and engine torques and electric drive recuperation, and current solutions are either economically impractical or complex to manufacture.
Innovation Solution
A press connection design with an axle journal featuring a first section with constant toothing and a second section with reduced tooth gaps, allowing manual assembly without additional pressing equipment, and a clamping device that ensures high pressure and torsional rigidity to prevent slipping and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the friction at the axle journal shoulder is increased to prevent slippage, then noise is reduced, but additional materials or components (diamond mesh, coated discs) are required which increases complexity and cost
Solution Approach 1:
The invention applies local quality by creating a differentiated tooth profile along the axial length of the spline connection. The first section has a first tooth profile while the second section has a second tooth profile with different friction characteristics. This allows the second section (near the shoulder) to provide high friction for noise prevention while the first section maintains easier engagement characteristics, eliminating the need for additional friction-enhancing materials.
2Object-affected harmful factors
If bonding or pressing is used to eliminate play and prevent noise, then noise is reduced, but additional effort during assembly and service is required
Solution Approach 1:
The invention implements dynamics by designing a spline connection that transitions from a play-prone state during initial insertion to a play-free state under operating load. The differentiated tooth profiles ensure that during normal operation with clamping force applied, the second section engages tightly against the shoulder, eliminating play and noise without requiring permanent bonding or complex pressing equipment.
3Object-affected harmful factors
If the tooth gaps are continuously expanded in the longitudinal direction to achieve zero backlash, then noise is reduced, but the manufacturing process becomes very complex and uneconomical for series production
Solution Approach 1:
The invention applies segmentation by dividing the spline toothing into distinct sections along the axial direction. Instead of continuously varying tooth gaps throughout the entire length, the toothing is segmented into a first section with one profile characteristic and a second section with another profile characteristic. This segmented approach achieves the necessary zero-backlash engagement near the shoulder while maintaining simpler, more economical manufacturing for the remaining length.
4Strength
If the teeth are made increasingly narrower toward one side to achieve even torque distribution, then torque transfer is improved, but manual assembly becomes impossible
Solution Approach 1:
The invention applies local quality by creating a differentiated tooth profile along the axial length of the spline connection. The first section has a first tooth profile while the second section has a second tooth profile with different friction characteristics. This allows the second section (near the shoulder) to provide high friction for noise prevention while the first section maintains easier engagement characteristics, eliminating the need for additional friction-enhancing materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enables reliable noise reduction and economical large-scale production by allowing manual assembly and high-pressure engagement, reducing manufacturing complexity and noise issues under high torque conditions.
Implementation Method 1
Torque is transferred from the drive shaft to the vehicle wheel via the gear profiles on the axle journal and the wheel hub. However, due to the axial tension described above, torque is also transferred via friction to the shoulder surface of the axle journal.
Data Source
Figure 1
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AI summary
A fitting connection comprises a hub (10) with a toothed profile (13) on its inner circumference, a journal (20) with a toothed profile (23) on an outer circumferential section (24) and a shoulder (22) for axial support and/or contact against the hub (10), and a clamping device (30) for axially clamping the journal (20) to the hub (10). The hub (10) has a constant toothed profile (13) along its toothed length. The journal (20) has a first section (27) and a second section (28) with different toothed profiles (23a, 23b) along its toothed length. The first section (27) is located further away from the shoulder (22) on the insertion side than the second section (28) and has a constant tooth profile (23a) with clearance to the tooth profile (13) of the hub.The second section (28) is arranged on the shoulder side and has a tooth profile (23b) with reduced tooth gaps compared to the first section (27), which is backlash-free with the tooth profile (13) of the hub (10). Furthermore, the second section (28) is arranged such that it can only be pressed into the hub (10) without backlash after the first section (27) has been inserted into the hub (10) with some play, and then the clamping device (30) has been tightened. Manufacturing methods for corresponding axle journals (20) are also disclosed.