Eccentric Worm Sleeve for Precise Steering Gear Backlash Adjustment

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing electro-hydraulic power steering systems in vehicles face inefficiencies and noise issues due to improper backlash adjustment between the worm gear and worm, leading to increased friction, wear, and fluctuating torque and speed, which affect steering feel and stability.

Innovation Solution

An adjusting device for backlash between the worm gear and worm, utilizing an eccentrically arranged adjusting sleeve that allows rotation to adjust the center distance between the worm and worm gear axes, eliminating components like adjusting springs and pendulum bearings for a simpler, cost-effective design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the center distance is slightly smaller and the backlash is excessively small, then the worm gear and worm are tightly meshed, but the frictional force increases, gear efficiency decreases, and wear of tooth surfaces increases

Engineering Contradiction:
Improvemeshing tightnessVSAvoidfrictional force
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent employs a dynamic adjustment mechanism that allows the center distance between the worm gear and worm to be modified during operation or assembly. By making the system adjustable rather than fixed, the optimal center distance can be achieved to balance meshing tightness with acceptable friction levels, resolving the contradiction between reliable engagement and energy loss.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the critical parameter of center distance from a fixed value to an adjustable variable. Through the adjustment mechanism involving the adjusting sleeve and bearing position modification, the center distance can be optimized to prevent excessive tightness that causes high friction and wear, while maintaining sufficient engagement for reliability.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the center distance is somewhat larger and the backlash is excessive, then the worm gear and worm are loosely meshed, but noise increases and service life of tooth surfaces decreases

Engineering Contradiction:
Improvefrictional forceVSAvoidnoise
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The adjustable center distance mechanism enables dynamic optimization of the meshing condition. Rather than being locked in a loose configuration that causes noise, the system can be adjusted to achieve the precise center distance needed for quiet operation with minimal backlash, eliminating the harmful noise effect while maintaining low friction.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By making the center distance a可调 parameter through the adjustment mechanism, the system can be tuned to the optimal value that minimizes both friction and noise. This parameter change allows the system to avoid the harmful effects of excessive backlash while maintaining efficient power transmission.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the bearing position is adjusted to modify center distance, then backlash is adjusted, but the worm's central axis displacement creates an angle between centerlines, causing torque and speed fluctuations

Engineering Contradiction:
Improvebacklash adjustmentVSAvoidtorque and speed stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention separates the adjustment function from the rotational support function by using distinct components: the adjusting sleeve for position adjustment and the bearing for stable rotation support. This segmentation allows backlash adjustment without compromising the alignment and stability of the worm's rotational axis, preventing torque and speed fluctuations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adjusting sleeve acts as an intermediary component that enables center distance modification without directly affecting the worm's rotational axis alignment. By introducing this intermediate adjustment mechanism, the system can modify backlash while maintaining the coaxial relationship between the motor output shaft and worm, ensuring stable torque and speed transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If traditional backlash adjustment mechanisms are used, then backlash can be adjusted, but the device complexity increases with additional components like adjusting springs and pendulum bearings

Engineering Contradiction:
Improvebacklash adjustment capabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the adjustment function into the existing bearing support structure. The adjusting sleeve integrates with the bearing assembly, eliminating the need for separate adjusting springs, pendulum bearings, and other auxiliary components. This consolidation maintains backlash adjustment capability while significantly reducing device complexity and component count.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The adjusting sleeve serves multiple functions: it provides backlash adjustment, supports the worm rotation, and maintains axial positioning. By making this single component multi-functional, the invention eliminates the need for multiple specialized components, reducing overall device complexity while maintaining adjustment capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 a quick and accurate backlash adjustment, reducing friction and noise, enhancing steering efficiency and stability by maintaining consistent torque and speed transmission.

Implementation Method 1

an adjusting sleeve located outside the worm and enabling rotation of the worm about the first central axis within the adjusting sleeve, wherein the adjusting sleeve is arranged eccentrically to the worm and by rotating the adjusting sleeve a position of the first central axis of the worm is changed

Methodology Applied
Scientific EffectEccentric arrangement: Eccentric

Data Source

PatentEP4722078A1Adjustment device for tooth-to-tooth gap between worm gear and worm, and steering transmission mechanism
Publication Date: 2026.04.08 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP4722078A1 patent drawingFigure 1
  • EP4722078A1 patent drawingFigure 2
  • EP4722078A1 patent drawingFigure 3

AI summary

Adjusting device for backlash between a worm gear and a worm, and a steering gear mechanism. The adjusting device (100) for backlash between a worm gear and a worm comprises: a worm (10) rotatable about a first central axis (O1); a worm gear (20) rotatable about a second central axis (O2) and meshing with the worm (10); and an adjusting sleeve (30) located outside the worm (10), in which the worm (10) can rotate about the first central axis (O1), and which is arranged eccentrically to the worm (10). The position of the worm changes with the rotation of the adjusting sleeve, so that the center distance between the worm and the worm gear changes, thereby achieving rapid adjustment of the backlash between the worm and the worm gear.