Recirculating-Ball Steering Gear Layout With Parallel Worm Drives

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Solution Overview

Problem

Existing electrically-powered recirculating-ball steering gear assemblies require complex engineering due to the placement of drive systems in series upstream of the worm, leading to increased complexity and packaging footprint.

Innovation Solution

The drive systems are placed in parallel at each end of the worm shaft, reducing complexity and footprint, and improving packaging efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drive systems are placed in series upstream of the worm shaft, then steering force can be provided through multiple drive systems, but the engineering complexity and packaging footprint increase significantly

Engineering Contradiction:

Improvesteering force provisionVSAvoidengineering complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of placing drive systems in series upstream of the worm shaft as in conventional designs, the patent inverts the arrangement by placing drive systems at opposite ends of the worm shaft in parallel. Each drive system engages with opposite ends of the worm shaft, eliminating the need for complex series upstream arrangements while maintaining the capability to provide steering force through multiple drive systems.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If drive systems are placed in series upstream of the worm shaft, then steering force can be provided through multiple drive systems, but the packaging footprint increases

Engineering Contradiction:

Improvesteering force provisionVSAvoidpackaging footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent inverts the conventional series upstream arrangement by placing drive systems at opposite ends of the worm shaft in parallel. This inversion allows the drive systems to be positioned more efficiently within the available space, reducing the overall packaging footprint while maintaining the ability to provide steering force through multiple drive systems.

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If drive systems are placed in parallel at each end of the worm shaft, then engineering complexity and footprint are reduced, but the arrangement must accommodate drive systems at both ends

Engineering Contradiction:

Improveengineering complexityVSAvoidarrangement configuration

Core Design Contradiction:

Device complexityVSShape

Solution Approach 1:

The patent divides the drive system arrangement into two separate segments, with each drive system positioned at one end of the worm shaft. This segmentation allows each drive system to be independently designed and positioned, simplifying the overall engineering while accommodating the parallel configuration at both ends of the worm shaft.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3585673B1Electrically-powered recirculating-ball steering gear assembly

Publication Date: 2025.05.14 CHINA AUTOMOTIVE SYSTEMS INC

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AI summary

A worm shaft (46) has a first end section (52) and a second end section (54) extending from a worm seciion (50), A first drive system (98) is in driving engagement with the first end seciion (52) of the worm shaft (46), and a second drive system (104) is in driving engagement with the second end section (54) of the worm shaft (46) for redundantly steering a vehicle. The worm section (50) of the worm shaft (46) is disposed between the first drive system (98) disposed on the first end section (52) of the worm shaft (46) and the second drive system (104) disposed ore the second end section (54) of the worm shaft (46), A lost motion connection (82) is disposed between an input shaft (76) and said worm shaft (46).