Steering Column Layout With Dual Worm Gears for Rattle Reduction
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Solution Overview
Problem
Existing steer-by-wire steering column assemblies face challenges in compactness and gear rattle, particularly due to limited installation space and the need to reduce gear rattle when torque direction is reversed.
Innovation Solution
A steering column assembly with inclined rotational axes of worm screws and a control arrangement that includes a circuit board with motor output position sensors, allowing for a more compact design and reduced gear rattle by using two oppositely-handed worm screws with a straight-cut gear and a circuit board positioned between the motors and worm screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the steering column assembly is made compact to reduce space intrusion, then the available installation space is optimized, but the space for driver's feet may be reduced
Solution Approach 1:
The patent repositions the ECU from a conventional location below the motors to a position beyond the end of the steering column (toward the dashboard). This spatial redistribution in a different dimension allows the steering column assembly to be more compact without encroaching on driver foot space, as the ECU is relocated to an underutilized space in the longitudinal direction rather than competing for vertical space below the steering column.
2Stability of the object's composition
If two worm screws are used to reduce gear rattle, then the gear engagement stability is improved, but the device complexity increases
Solution Approach 1:
The patent combines the control functions for both worm screws into a single integrated circuit board that houses both motor output position sensors and serves as the control arrangement. This merging of control elements reduces the overall complexity that would otherwise arise from having separate control systems for each worm screw, while still achieving the gear rattle reduction benefit of dual worm screw engagement.
Solution Approach 2:
The patent employs oppositely-handed worm screws (one left-handed, one right-handed) that are inclined at different angles relative to the steering column axis. This asymmetric configuration allows the two worm screws to engage the straight-cut gear in opposite directions, providing balanced torque application that reduces gear rattle while maintaining compact dimensions. The asymmetric design optimizes the gear engagement stability without requiring symmetric, overly complex positioning systems.
3Ease of operation
If the ECU is positioned beyond the steering column to optimize driver foot space, then the driver comfort is improved, but the steering column assembly length increases
Solution Approach 1:
The circuit board positioned beyond the steering column serves multiple functions: it acts as the control arrangement for both motors, houses both motor output position sensors, and serves as the mounting platform for the ECU. This multi-functional integration allows the ECU to be positioned beyond the steering column without proportionally increasing the overall assembly length, as multiple components are consolidated into this single location rather than requiring separate spaces for each function.
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 enhances space utilization and reduces gear rattle, enabling a more compact installation and improved driver comfort by allowing the ECU to be positioned beyond the steering column, thus optimizing space for the driver's feet.
Implementation Method 1
The output of each of the first and second motors may carry a magnet which interacts with the respective motor output position sensor
Data Source
AI summary
A steering column assembly for a vehicle comprises a steering column mounted for rotation about its longitudinal axis and configured for attachment to a steering wheel at one end; a first gear connected to the steering column at a location spaced from the end where the steering wheel may be attached and configured to rotate with the steering column; first and second motors; first and second worm screws connected to and rotatable with an output of the first and second motors respectively and engaged with the first gear; and a control arrangement configured to operate the first and second motors. The control arrangement comprises a circuit board located between the first and second worm screws and their respective motors. The circuit board comprises a motor output position sensor for each of the first and second motors.