Steering Column Friction Adjustment for Energy-Efficient Depth Control

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Solution Overview

Problem

Conventional steering column adjustment mechanisms require high friction forces between telescopic tubes for stiffness, leading to increased energy consumption and motor size, especially during autonomous driving where larger retraction strokes are needed, resulting in longer adjustment times and higher costs.

Innovation Solution

A friction adjustment device with a clamping screw and clamping elements that vary friction by modifying the spacing between these elements, allowing for reduced friction during adjustment modes without compromising stiffness, using a compact and energy-efficient mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high friction force is applied between telescopic tubes to ensure column stiffness, then steering column rigidity is improved, but energy consumption and motor size increase

Engineering Contradiction:
Improvecolumn stiffnessVSAvoidenergy consumption
Core Design Contradiction:
StrengthVSUse of energy by moving object

Solution Approach 1:

The friction force between the telescopic tubes is made dynamically adjustable through a friction adjustment device that can vary the clamping force between the tubes. During adjustment mode, the friction force is reduced to enable smooth movement with lower energy consumption. During operational mode, the friction force is increased to ensure column stiffness and prevent deflection. This dynamic adaptation resolves the contradiction by having high friction only when needed for stiffness, not continuously during adjustment.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The physical parameter of friction force between the telescopic tubes is changed based on operational requirements. A friction adjustment device modifies the clamping force between the tubes, thereby changing the friction coefficient. This allows the system to operate with low friction during adjustment (reducing energy consumption) and high friction during operation (maintaining stiffness), thus resolving the technical contradiction through parameter variation.

Inventive Principle:
Principle #35Parameter changes

2Strength

If high friction force is applied between telescopic tubes to ensure column stiffness, then steering column rigidity is improved, but motor size and cost increase

Engineering Contradiction:
Improvecolumn stiffnessVSAvoidmotor size
Core Design Contradiction:
StrengthVSPower

Solution Approach 1:

The friction force is made dynamically adjustable to match operational requirements. During adjustment mode, the friction force is reduced, allowing a smaller motor to achieve the necessary adjustment speed without being oversized for the high-friction operational mode. During operational mode, the friction force is increased to maintain stiffness. This dynamic adjustment allows the motor to be sized appropriately for the adjustment task without requiring excessive power capacity.

Inventive Principle:
Principle #15Dynamics

3Length of moving object

If large retraction stroke is implemented for autonomous driving, then steering wheel retraction capability is improved, but adjustment time increases

Engineering Contradiction:
Improveretraction strokeVSAvoidadjustment time
Core Design Contradiction:
Length of moving objectVSLoss of time

Solution Approach 1:

The friction force is dynamically reduced during adjustment mode to enable faster movement of the telescopic tubes. This reduced friction allows the system to achieve large retraction strokes (2-5 times greater than comfort adjustment) without proportionally increasing adjustment time. The low-friction state during adjustment facilitates rapid retraction while the friction is restored during operational mode to maintain stiffness.

Inventive Principle:
Principle #15Dynamics

4Length of moving object

If large retraction stroke is implemented for autonomous driving, then steering wheel retraction capability is improved, but energy consumption increases

Engineering Contradiction:
Improveretraction strokeVSAvoidenergy consumption
Core Design Contradiction:
Length of moving objectVSUse of energy by moving object

Solution Approach 1:

The friction force is dynamically adjusted to be low during adjustment mode, enabling large retraction strokes with reduced energy consumption. By reducing the frictional resistance during the adjustment phase, the motor requires less power to achieve the same retraction distance, thus resolving the contradiction between achieving large retraction strokes and minimizing energy consumption.

Inventive Principle:
Principle #15Dynamics

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

This solution enables faster and more energy-efficient steering wheel adjustments while maintaining column stiffness, reducing the need for powerful motors and minimizing energy consumption, especially in autonomous driving modes.

Implementation Method 1

the friction force between the inner tube and the outer tube can be motorizedally adjusted

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3971055B1Steering column with motorised depth adjustment comprising a system for adjusting the friction between two tubes sliding into one another
Publication Date: 2023.07.05 ROBERT BOSCH AUTOMOTIVE STEERING VENDOME SAS
  • EP3971055B1 patent drawingFigure 1
  • EP3971055B1 patent drawingFigure 2
  • EP3971055B1 patent drawingFigure 3

AI summary

The invention relates to a friction adjustment device (9) between an outer tube (4) and an inner tube (3) of a motorized steering column (1) with at least depth adjustment, wherein the outer and inner tubes (3, 4) are coaxial and slide relative to each other. The friction adjustment device (9) comprises an actuator (7) and a clamping screw (13) driven in rotation by the actuator (7) and mechanically connected to the outer tube (4) and extending along a clamping axis substantially orthogonal to an adjustment axis. It further comprises a first clamping element located on one side of an axial plane (P) including the adjustment axis; and a second clamping element located on the other side of said axial plane (P).The first and second clamping elements exert pressure on the inner tube (3), and the rotation of the clamping screw (13) generates a translational movement of at least one of the first and second clamping elements substantially parallel to the clamping axis such that the friction varies according to the gap between the first and second clamping elements. This gap varies between an operating position and at least one adjustment position in which the friction is less than that in the operating position.