Composite Worm Wheel Structure for Quiet, Durable Steering Reducers
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Solution Overview
Problem
Conventional power steering apparatuses experience reduced durability and increased vibration and noise due to the direct transmission of rotational forces through the worm shaft, worm wheel, and steering shaft, particularly when driving on uneven roads, leading to discomfort for the driver.
Innovation Solution
The design of a worm wheel with a gear part featuring crests and roots, and insert parts with lateral side protrusions, depressions, and end protrusions, which enhance the formability, precision, mechanical strength, and durability of the worm wheel, allowing stable operation under high power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional worm wheel is used for power transmission, then the reducer can transmit torque from the worm shaft to the steering shaft, but the worm wheel exhibits insufficient mechanical strength and durability, leading to component destruction under high load conditions
Solution Approach 1:
The worm wheel is constructed as a composite structure consisting of a gear part and an insert part made of different materials. The gear part is made of a softer material while the insert part is made of a harder material with higher mechanical strength. This composite construction allows the worm wheel to achieve both the durability needed for long-term operation and the mechanical strength required to withstand high load conditions without component destruction
2Power
If the worm shaft, worm wheel, and steering shaft are engaged for torque transmission, then the power steering apparatus can provide steering assistance, but vibration and noise are directly transmitted to the driver, causing discomfort particularly on uneven roads
Solution Approach 1:
The insert part serves as an intermediary element between the worm shaft and the gear part. This insert part is designed to absorb and dampen vibrations generated during engagement, preventing direct transmission of vibration and noise to the driver through the steering shaft. The insert part acts as a mediator that maintains torque transmission capability while reducing harmful vibrations and noise
3Ease of manufacture
If the worm wheel is designed with simple structure for ease of manufacture, then production cost is reduced, but the formability and precision of the worm wheel are insufficient, affecting stable operation under high power transmission
Solution Approach 1:
The worm wheel is segmented into two distinct parts: a gear part and an insert part. The gear part can be manufactured using conventional processes, while the insert part is separately manufactured with high precision and then assembled into the gear part. This segmentation allows each part to be optimized for its specific manufacturing requirements, achieving both ease of manufacture and high precision
Data Source
AI summary
A reducer of a power steering apparatus for vehicle. The formability and precision of a worm wheel is improved. The mechanical strength and durability of the worm wheel is increased so the reducer can be stably driven for a long time when a high power is transmitted from a worm shaft to a steering shaft through the worm wheel.