Recirculating Ball Gear Progressive Spring Damping

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Solution Overview

Problem

Recirculating ball gears face damage and rattling noises due to axial shocks and play in the bearing, which existing designs fail to absorb effectively, especially when the spring travel required for damping is minimal.

Innovation Solution

The implementation of spring elements with specific preload and a steeply rising characteristic curve to reliably dampen axial impacts, using corrugated springs or elastomer disks, connected in parallel or series, to manage the small play and reduce rattling noises.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If one-sided spring action is used to fix the bearing, then the bearing is fixed in the housing and tilting moments are compensated, but axial shocks cannot be absorbed

Engineering Contradiction:
Improvebearing fixationVSAvoidaxial shock damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by using different spring arrangements on each side of the bearing. One side has a first spring element for compensating tilting moments, while the other side has a second spring element for absorbing axial shocks. This asymmetric configuration allows each side to address specific mechanical challenges independently, resolving the contradiction between bearing fixation and shock absorption.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent segments the spring support system into two distinct functional parts: a first spring element for tilting moment compensation and a second spring element for axial shock absorption. This segmentation allows each spring element to be optimized for its specific function, enabling the bearing to simultaneously maintain fixation while absorbing shocks.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If spring elements with large travel are used for damping, then axial shocks can be absorbed, but the spring travel required exceeds the available clearance in the bearing

Engineering Contradiction:
Improveaxial shock absorptionVSAvoidspring travel distance
Core Design Contradiction:
Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The patent changes the mechanical parameters of the spring elements by introducing progressive spring characteristics with non-linear force-displacement relationships. This allows the springs to provide adequate damping force within the limited clearance available in the bearing housing, eliminating the need for excessive spring travel while still absorbing axial shocks effectively.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs dynamic spring elements with progressive characteristics that adjust their stiffness based on the applied load. During normal operation, the springs remain relatively compact, but during axial shock events, they dynamically increase their damping capacity, providing effective shock absorption within the constrained spatial envelope of the bearing assembly.

Inventive Principle:
Principle #15Dynamics

3Object-generated harmful factors

If preload force is increased to reduce bearing play, then rattling noises are reduced, but the spring element operates near the steep region of the characteristic curve where damping capacity is reduced

Engineering Contradiction:
Improverattling noisesVSAvoidshock load damping
Core Design Contradiction:
Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The patent segments the spring support system into two distinct functional parts: a first spring element for tilting moment compensation and a second spring element for axial shock absorption. This segmentation allows each spring element to be optimized for its specific function, enabling the bearing to simultaneously maintain fixation while absorbing shocks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the mechanical parameters of the spring elements by introducing progressive spring characteristics with non-linear force-displacement relationships. This allows the springs to provide adequate damping force within the limited clearance available in the bearing housing, eliminating the need for excessive spring travel while still absorbing axial shocks effectively.

Inventive Principle:
Principle #35Parameter changes

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 effectively absorbs axial shocks and significantly reduces rattling noises by utilizing spring elements with a progressive characteristic curve, ensuring reliable damping even with minimal spring travel.

Implementation Method 1

A first spring element (24) is arranged on each end face of the bearing (20) between the outer ring (22) and stop elements (26)... the spring elements (24) dampen shock loads acting axially on the bearing (20)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The spring elements can have a specific preload, with the preload travel and preload force lying within a low-slope section of the progressive characteristic curve. This dampens rattling noises resulting from bearing play.

Methodology Applied
Scientific EffectHysteresis: Hysteresis

Data Source

PatentEP2576320B1Recirculating ball gear
Publication Date: 2015.03.11 ROBERT BOSCH AUTOMOTIVE STEERING
  • EP2576320B1 patent drawingFigure 1~2
  • EP2576320B1 patent drawingFigure 3~4

AI summary

The invention relates to a recirculating ball gear, in particular for a steering system of a motor vehicle, comprising a nut (21) mounted in a housing by means of a bearing (20), wherein at least one spring element (24) is arranged at each end face of the bearing (20) between the bearing (20) and the housing. During operation, the recirculating ball gear is subjected to impact in the axial direction, as a result of which damage and annoying rattling noise can occur in the recirculating ball gear over time. The spring elements (24) are therefore operated according to the invention in the progressive range of a characteristic curve.