Multi-Piece Gearwheel Undercut Teeth for Steering Gearbox Life
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Solution Overview
Problem
Multi-piece gearwheels in electromechanically-assisted steering systems experience large tensile stresses and material fatigue due to disengagement between the outer toothed ring and the core section, leading to a shorter gearwheel life.
Innovation Solution
The design incorporates intermeshing teeth with radial undercuts on the core section that fit into recesses on the toothed ring, ensuring direct force transmission and preventing disengagement, with the intermeshing teeth being arranged in a manner that optimizes power transmission and material distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the outer toothed ring and core section are connected without radial undercuts, then the manufacturing is simpler, but the tensile stresses cause disengagement and material fatigue leading to shorter service life
Solution Approach 1:
The gearwheel is divided into two separate parts: an outer toothed ring and an inner core section with intermeshing teeth. This segmentation allows each part to be optimized independently, with the intermeshing teeth providing positive mechanical connection to prevent disengagement under tensile stresses, thereby extending service life while maintaining manageable manufacturing complexity.
Solution Approach 2:
The intermeshing teeth extend in the radial direction with undercut profiles, adding a radial dimension to the connection mechanism. This radial extension creates overlapping tooth profiles that mechanically lock the outer ring and core section together, preventing circumferential disengagement and reducing material fatigue from tensile stresses.
2Reliability
If the intermeshing teeth have radial undercuts extending further radially, then the positive connection and force transmission is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The intermeshing teeth of the core section are nested within the tooth spaces of the outer ring, creating a interlocking configuration. This nesting arrangement ensures that the undercut profiles of the intermeshing teeth engage with the outer ring's tooth profiles, providing reliable positive mechanical connection and force transmission while distributing loads across multiple contact points.
Solution Approach 2:
The gearwheel combines two different components (outer toothed ring and inner core section) with potentially different material properties. This composite structure allows optimization of each component for its specific function: the outer ring for load-bearing and the core section with intermeshing teeth for positive mechanical connection, thereby achieving reliable power transmission.
3Power
If the intermeshing teeth are arranged to completely fill the recesses, then the force transmission is optimized, but the manufacturing complexity increases
Solution Approach 1:
The intermeshing teeth are designed to extend radially with undercut profiles that partially overlap with the outer ring's tooth profiles. This partial extension beyond the basic tooth depth creates the necessary mechanical interlocking for reliable force transmission, while the systematic arrangement of these teeth follows regular patterns that manage manufacturing complexity.
Solution Approach 2:
The intermeshing teeth are strategically positioned and dimensioned to provide local mechanical interlocking at critical stress points. The undercut profiles are concentrated where they provide maximum benefit for preventing disengagement, while other areas maintain simpler geometries, thereby optimizing power transmission without excessive overall complexity.
Data Source
AI summary
A multi-piece gearwheel comprising an inner core section and an external toothed ring with external teething is presented. The core section has intermeshing teeth extending radially outwards, which have an undercut in cross-section in the radial direction. The toothed ring has recesses that originate from an inner side of the tooth ring and extend radially outwards, wherein the recesses are at least partially complementary to the intermeshing teeth, and wherein the intermeshing teeth are received in the recesses. Furthermore, a gearbox for an electromechanically-assisted steering system is described.