Injection-Molded Worm Gear Support Ring for Load Distribution
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Solution Overview
Problem
Worm gears in motor vehicle steering systems experience uneven force distribution and rapid wear due to sudden loads, leading to inefficient torque transmission.
Innovation Solution
A worm gear design featuring a carrier body injected between the ring gear and hub using injection molding, with support webs that distribute forces radially and are integrated with the ring gear to form teeth, enhancing torque transmission and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multi-part gear with a connecting part is used to link the hub to the gear ring, then the gear can be assembled, but the force distribution in the engagement area becomes uneven, leading to faster wear
Solution Approach 1:
The invention merges the connecting part, hub, and gear ring into a single integrated injection-molded component. The support ribs are formed as an integral part of the gear ring structure, eliminating the need for separate connecting parts and ensuring uniform force distribution throughout the engagement area, which prevents uneven wear while maintaining manufacturability through injection molding processes
2Power
If the tooth flanks are designed to engage the worm, then torque transmission is enabled, but the tooth flanks are overloaded by shock loads during normal operation
Solution Approach 1:
The invention introduces support ribs that extend in the axial direction (perpendicular to the tooth flanks), adding a new dimensional element to the force distribution system. These support ribs penetrate the gear ring and distribute shock loads axially, preventing overload of the tooth flanks while maintaining their torque transmission capability through the engagement with the worm
3Reliability
If the support ribs are made to penetrate the gear ring, then force distribution is improved and torque transmission is enhanced, but the structural complexity increases
Solution Approach 1:
The support ribs are designed to be self-formed during the injection molding process. The molten plastic naturally flows and solidifies into the rib structures that penetrate the gear ring, creating the force-distributing geometry without requiring additional manufacturing steps, assembly operations, or complex tooling. The structure serves its own formation purpose through the manufacturing process itself
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 improved force distribution and higher torque transmission capabilities, reducing wear and enhancing the durability of the worm gear.
Implementation Method 1
a support body, which is a support ring injected between the toothed ring and the hub by injection molding
Data Source
Figure 1~3
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Figure 9~12
AI summary
The invention relates to a worm gear (12) for a worm gear system (11) in a motor vehicle steering device, comprising a hub (15), a support body (16) and a ring gear (17), the support body (16) being a support ring which is injection moulded between the ring gear (17) and the hub (15) by means of an injection moulding method, which support ring interlockingly interconnects the hub (15) and the ring gear (17), the ring gear (17) and the support body (16) forming a plurality of teeth (18) and the support body (16) comprising support ribs (164) which pass through the ring gear (17) such that the radially outwardly pointing end faces (166) of the support ribs (164) are exposed.