Torque Overlay Steering with Worm Drive Torque Multiplication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torque overlay steering apparatuses occupy excessive space in the passenger compartment and have insufficient torque multiplication, failing to adequately reduce operator effort in steering wheeled vehicles.
Innovation Solution
A compact steering apparatus utilizing a gear train with a worm screw and worm wheel, providing a high torque multiplication ratio of 16-22:1, which includes a motor with a drive shaft and an output shaft connected via a gear train, allowing for efficient torque supplementation to the steering shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a belt drive is used to mechanically couple the motor to the steering shaft, then the torque overlay steering apparatus can be mounted in the passenger compartment, but the torque multiplication ratio is limited to 3:1 which is insufficient for adequate torque supplementation
Solution Approach 1:
A worm screw acts as an intermediary mechanical element between the motor and the output shaft, enabling high torque multiplication through its engagement with the worm wheel. This intermediary component transforms the motor's rotational motion into high-torque output while maintaining a compact structure suitable for passenger compartment mounting.
Solution Approach 2:
The patent replaces the belt drive mechanical coupling system with a worm screw-worm wheel gear train. This substitution eliminates the torque limitation of belt drives (3:1 ratio) and provides superior torque multiplication (16-22:1 ratio) while maintaining mechanical reliability for steering applications.
2Force
If known torque overlay steering apparatuses are designed with sufficient torque multiplication capability, then adequate torque supplementation can be achieved, but they occupy an undesirably large amount of space in the passenger compartment
Solution Approach 1:
The gear train components (worm screw, worm wheel, bevel gears) are nested within a compact housing structure. The counter shaft is positioned concentrically with the output shaft, and gear components are arranged in nested configurations that minimize the overall volume occupied by the torque overlay steering apparatus while maintaining high torque multiplication capability.
Solution Approach 2:
The patent employs three-dimensional spatial arrangement of gear components, utilizing vertical and radial dimensions efficiently. The worm screw engages with the worm wheel in a vertical arrangement, while bevel gears transmit motion between perpendicular shafts, optimizing space utilization in all three dimensions to reduce the apparatus's footprint in the passenger compartment.
3Object-affected harmful factors
If the torque overlay steering apparatus is mounted in the engine bay, then it can avoid harsh conditions in the passenger compartment, but the apparatus would be exposed to extreme temperatures and contaminants
Solution Approach 1:
The patent converts the potential harm of mounting in the engine bay by selecting engine bay mounting as the preferred location, thereby protecting the apparatus from operator exposure while managing thermal and environmental conditions through proper sealing and component selection. The harsh engine bay environment becomes acceptable through protective design measures.
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 enables a significant reduction in space occupancy in the passenger compartment while providing a substantial torque multiplication, enhancing the vehicle's maneuverability, especially in cases of hydraulic power steering system failure.
Implementation Method 1
The gear train includes a worm screw and a worm wheel
Implementation Method 2
providing a high torque multiplication ratio of 16-22:1
Implementation Method 3
A motor having a drive shaft that rotates about a drive shaft axis
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A steering apparatus (10) for assisting rotation of a steering shaft (114) in a steering system (110). The apparatus (10) includes a motor (60) having a drive shaft (62) that rotates about a drive shaft axis (64) and an output shaft (40) that rotates about an output shaft axis (94). The output shaft axis (94) extends parallel to the drive shaft axis (64). The output shaft (40) is connected for rotation with the steering shaft (114). A gear train (20) drivingly connects the motor (60) to the output shaft (40). The gear train (20) includes a worm screw (26) and a worm wheel (28).