Camming Drive Pulley Assembly for EPS Belt Self-Alignment
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Solution Overview
Problem
Existing power steering systems require an additional idler cam/pulley for belt tension adjustment, leading to increased cost and friction, and are susceptible to misalignment due to bearing bore offsets, with excess load on drive pulley bearings.
Innovation Solution
A power steering system with a camming drive pulley that uses a single bearing and a mechanical fastener with an offset axis to maintain belt tension, eliminating the need for an idler pulley and allowing self-alignment of the drive pulley with the driven pulley.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an idler cam/pulley is used for belt tension adjustment, then belt tension can be adjusted, but device complexity increases and system friction increases
Solution Approach 1:
The patent removes the idler cam/pulley component from the system entirely. Instead of using a separate idler wheel with a camming device for tension adjustment, the drive pulley itself is designed with an integrated camming surface that directly adjusts belt tension when the power pack shaft is positioned, eliminating the need for the additional idler component.
Solution Approach 2:
The patent combines the tension adjustment function into the drive pulley assembly itself. The camming surface is integrated into the drive pulley structure, and the positioning of the power pack shaft relative to the drive pulley automatically provides both drive engagement and belt tension adjustment in a single integrated mechanism.
2Reliability
If an idler cam/pulley is used for belt tension adjustment, then belt tension can be adjusted, but manufacturing cost increases
Solution Approach 1:
By removing the idler cam/pulley component, the patent reduces the number of parts that need to be manufactured, inventoried, and assembled. This elimination of components directly reduces manufacturing complexity and associated costs while maintaining the essential belt tension adjustment capability through the integrated camming drive pulley design.
3Ease of manufacture
If bearing bore offsets are present, then assembly is simplified, but misalignment occurs
Solution Approach 1:
The patent intentionally introduces an offset between the power pack shaft axis and the drive pulley axis. This asymmetric positioning creates a camming action that generates the necessary belt tension while allowing the bearing bores to be positioned for simplified assembly. The offset transforms a potential alignment problem into a functional feature for tension generation.
Solution Approach 2:
The patent changes the geometric parameters of the drive system by introducing controlled offsets between shaft and pulley axes. This parameter change enables the system to achieve both simplified assembly and proper alignment through the camming action, rather than requiring precise coaxial alignment.
4Reliability
If two bearings are used in the drive pulley, then radial support is improved, but excess load capacity is wasted
Solution Approach 1:
The patent removes one bearing from the traditional two-bearing configuration. The drive pulley is redesigned to be supported by a single bearing located at one end, eliminating the redundant bearing and its associated mounting features while maintaining adequate radial support for the pulley operation.
Data Source
AI summary
A power steering system includes a rack housing arranged to receive a longitudinally displaceable rack member. The system also includes an assist cover connected to the rack housing, the rack housing and the assist cover defining a cavity. The system further includes an assist assembly at least partially disposed within the cavity. The assist assembly includes a power pack connected to the rack housing, the power pack having a power pack shaft extending therefrom. The assist assembly also includes a drive pulley coupled to the power pack shaft. The assist assembly further includes a single bearing disposed within a bore defined by the drive pulley. The assist assembly yet further includes a mechanical fastener coupling the drive pulley to the assist cover. The assist assembly also includes a driven pulley disposed about the rack member.