Steering Shaft Bearing Assembly With Fail-Safe Feedback Cam
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Solution Overview
Problem
Existing motor vehicle steering shaft bearing devices lack clear feedback to drivers when rolling elements are lost or destroyed, leading to potential total failure without noticeable steering issues.
Innovation Solution
A bearing device with a positive locking cam and safety contour that provides tactile and acoustic feedback through a defined relative movement, ensuring torque transmission is maintained while alerting the driver to potential issues via increased steering play and audible clicks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a positive locking cam with safety contour is provided to prevent total failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The positive locking cam and safety contour are pre-configured to automatically engage when rolling elements are lost, providing fail-safe protection without requiring additional sensors or control systems. The cam is positioned and shaped in advance to detect bearing groove occupancy and switch between engagement states passively.
Solution Approach 2:
The bearing device uses its own structural components (cam and safety contour) to detect and respond to rolling element loss. The system self-diagnoses the bearing state through the cam's automatic engagement/disengagement based on whether bearing grooves are occupied, eliminating the need for external monitoring systems.
2Reliability
If rolling elements are lost, then torque transmission fails, but with positive locking cam torque transmission is maintained through mechanical redundancy
Solution Approach 1:
The positive locking cam and safety contour are designed as a pre-prepared backup mechanism that automatically activates when rolling elements are lost. The cam's geometry and positioning are arranged in advance to provide alternative torque transmission paths, cushioning against complete system failure.
3Ease of operation
If a small air gap is provided between cam and groove, then axial displacement is enabled, but tactile feedback is insufficient for driver awareness
Solution Approach 1:
The system provides tactile feedback to the driver through the steering wheel by allowing the positive locking cam to move along the safety contour when bearing grooves are unoccupied. This creates perceptible steering play that directly communicates the bearing's operational status to the driver through the steering mechanism.
Solution Approach 2:
The positive locking cam transitions from a static position to a dynamic one, moving along the safety contour when bearing grooves are unoccupied. This dynamic movement creates variable steering play that provides tactile feedback to the driver, transforming the cam from a purely structural component to an active feedback mechanism.
Data Source
AI summary
A bearing device for motor vehicle shafts is described, in particular for motor vehicle steering shafts. The bearing device is provided for torque transmission between an inner shaft and the hollow shaft surrounded by the inner shaft. The inner shaft and the hollow shaft each have opposing bearing grooves, in which rolling elements are received. At least one positive locking cam in radial direction is provided. A safety contour is assigned to the positive locking cam, the safety contour comprising two engagement positions for the positive locking cam. In the case of unoccupied bearing grooves the positive locking cam is rotationally movable along the safety contour between the engagement points during a torque transmission, in a manner that a defined relative movement between the inner shaft and the hollow shaft is possible, which generates both tactile feedback and acoustic feedback. Furthermore, an automotive shaft assembly is described.