Steering Column Rotation Limiting Device with Spiral Cam Track
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Solution Overview
Problem
Steering columns in steer-by-wire systems face challenges with high susceptibility to tolerances and rattling issues, making safe operation and effective rotation limitation difficult.
Innovation Solution
A steering column design featuring a rotation limiting device with a connecting link carrier, a spiral link track, and a rocker assembly that includes counter-stops to limit rotation, combined with a torque-locking mechanism and damping bodies to prevent rattling and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical rotation limiter with balls and spiral tracks is used, then rotation limitation is achieved, but the device becomes highly susceptible to tolerances and rattling
Solution Approach 1:
The patent extracts the harmful rattling elements (balls in spiral tracks) from the rotation limiting mechanism and replaces them with a cam-based system. The cam carrier with cam track and cam block provides rotation limitation through geometric constraint rather than ball-and-track interaction, eliminating the source of rattling while maintaining the rotation limitation function.
Solution Approach 2:
The patent introduces a cam carrier as an intermediary element between the steering shaft bearing unit and the rotation limitation function. The cam carrier rotates with the steering shaft and carries the cam track, which guides the cam block. This intermediary mechanism provides smooth, continuous rotation limitation without the discontinuous contact and rattling associated with ball-based systems.
2Ease of operation
If simple mechanical stops are used to limit steering angle, then the maximum steering angle is limited, but the driver receives no feedback when maximum angle is reached
Solution Approach 1:
The patent implements feedback by having the cam block's movement through the cam track mechanically indicate when maximum steering angle is reached. As the cam carrier rotates with the steering shaft, the cam block follows the cam track's geometry, and when the cam block reaches specific positions in the cam track, it provides tactile feedback to the driver through the steering wheel, indicating that maximum steering angle has been achieved.
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 solution provides improved rotation limitation with reduced susceptibility to tolerances and noise, ensuring safe and reliable operation by effectively limiting steering shaft rotation and damping impacts.
Implementation Method 1
the rotation limiting device has a cam carrier attached to the steering shaft bearing unit and which has a spiral cam track surrounding the steering shaft, wherein a cam block is movably guided in the cam track
Implementation Method 2
the cam block is coupled to a rocker arm, wherein the rocker arm is tiltably held on the steering shaft
Implementation Method 3
the rocker arm has at least one counter stop which can be brought into effective engagement with a stop formed or attached to the steering shaft bearing unit to limit the rotation of the steering shaft
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The invention relates to a steering column (1) for a motor vehicle comprising a steering shaft (2) which is rotatably mounted in a steering shaft bearing unit (3), and a rotation limiting device (9) that is designed to limit the rotation of the steering shaft (2). The rotation limiting device (9) comprises a housing (10) that is secured to the steering shaft bearing unit (3), also comprising a guide support (13) with a spiral guide path (14) surrounding the steering shaft (12). A guide block (17) is displaceably guided into the guide track (14) and the guide block (15) is coupled to a rocker (21), said rocker being maintained so that it can tilt on the steering shaft (2). The rocker (21) has at least one counterstop (25) which can be operatively engaged with a stop (24) that is secured to the steering shaft bearing unit (3) for limiting the rotation of the steering shaft (2).