Dual Pinion Steering Gear Housing for Compact Worm Drive Packaging

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Solution Overview

Problem

Existing steering gears with separate gear housings for worm gears and multiple bearings are bulky, heavy, and have large tolerances due to numerous components and connection points, making them complex and costly to assemble.

Innovation Solution

A compact steering gear design with a one-piece gear housing that integrates the second pinion shaft housing, using a snap ring to fix the second roller bearing and a press-fitted worm gear, reducing the number of components and weight, and simplifying assembly by eliminating connecting and sealing elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate gearbox housings are used for worm gear and bearings, then the steering gear can accommodate multiple components, but the overall assembly becomes bulky and heavy with large tolerances

Engineering Contradiction:
Improvecomponent accommodationVSAvoidhousing weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent merges the separate gearbox housings for the worm gear and bearings into a single integrated housing structure. The housing (15) accommodates both the second steering pinion (8) with its bearings and the worm gear (24) with the worm shaft (25), eliminating the need for multiple separate housings and their associated connection points, thereby reducing overall weight and tolerance accumulation

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If separate gearbox housings are used for worm gear and bearings, then components can be independently assembled, but the number of components and connection points increases

Engineering Contradiction:
Improveindependent assemblyVSAvoidnumber of components
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent combines multiple housing components into a single integrated housing structure that accommodates both the second steering pinion assembly and the worm gear assembly. This reduces the total number of components and eliminates the need for connecting elements and sealing elements between separate housings, thereby simplifying the overall device complexity

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If multiple separate housings are used, then assembly flexibility is improved, but tolerances become undesirably large due to numerous connection points

Engineering Contradiction:
Improveassembly flexibilityVSAvoidassembly tolerance
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent integrates the housing for the second steering pinion and the housing for the worm gear into a single housing structure. This eliminates the connection points between separate housings, thereby eliminating the accumulation of tolerances that would result from multiple mating surfaces and fastening points, and achieving undesirably large tolerance reduction

Inventive Principle:
Principle #5Merging (Combining)

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 design reduces the axial height, weight, and tolerances, achieving a more compact and lightweight steering gear with simplified assembly and reduced production costs.

Implementation Method 1

Das zweite Kugellager ist mit einem Span ring, der an der Dre hachse entlang das zweite Kugellager festhält, in der Getriebekar verankert

Methodology Applied
Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 2

Das Wurmrad ist in einem Bereich der zweiten freien Endes des Lenk pinions pressfit gelagert

Methodology Applied
Scientific EffectWorm Drive: Worm Drive

Implementation Method 3

wobei das zweite Kugellager zwischen dem Zahnabschnitt und dem Wurmrad gelagert ist

Methodology Applied
Scientific EffectRolling Bearing: Ball Bearing

Data Source

PatentEP3720757B1Compact dual pinion steering transmission
Publication Date: 2022.09.07 THYSSENKRUPP PRESTA AG
  • EP3720757B1 patent drawingFigure 1~2
  • EP3720757B1 patent drawingFigure 3~4
  • EP3720757B1 patent drawingFigure 5~6

AI summary

The invention relates to a steering transmission comprising a transmission housing (15) in which a gear rack (5) is moveably mounted in a longitudinal direction, and comprising a first steering pinion (4) and a second steering pinion (8), each mounted such that they can rotate in the transmission housing (15) and having a toothed region (22), which engages with at least one toothing (6, 7) provided on the gear rack (5), wherein the first steering pinion (4) is operatively connected to a steering shaft (2, 3) supporting a steering wheel (1) and the second steering pinion (8) is operatively connected to an electric motor (26) via a worm drive (24, 25), and the second steering pinion (8) has a first free end (20) and a second free end (33), wherein the first free end (20) is mounted in a first rolling bearing (21) in the transmission housing (15) such that it can rotate about an axis of rotation, and the second free end (33) supports a worm wheel (24) of the transmission, characterised in that the second steering pinion (8) is mounted in a second rolling bearing (23) between the toothed region (22) and the worm wheel (24), and in that the outer ring of the second rolling bearing (31) is secured in the transmission housing (15) in the direction of the axis of rotation by means of a securing ring (31).