Globoidal Worm Power Steering for Heavy Electric Commercial Vehicles
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Solution Overview
Problem
Hydraulic power steering systems are not suitable for electric and hybrid commercial vehicles, as they pose challenges in providing a mechanical advantage and are not cost-effective or robust enough for heavy commercial vehicles.
Innovation Solution
An electric power steering system utilizing a globoidal worm gearing or double enveloping gearset, which includes a planetary gear set, drive coupling, and globoidal worm drive, provides a mechanical advantage for an electric motor to power the steering of heavy commercial vehicles, offering a compact, safe, and cost-effective solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic power steering is used in electric commercial vehicles, then the system can provide steering assistance, but it fails to provide sufficient mechanical advantage and is not cost-effective or robust enough for heavy commercial vehicles
Solution Approach 1:
The patent replaces the hydraulic power steering system with an electric motor-driven system. The electric motor (120) directly drives the steering mechanism through a planetary gear set (130) and globoidal worm drive (160), eliminating the need for hydraulic pumps, fluid reservoirs, and associated hydraulic components. This substitution makes the system suitable for electric vehicles while providing sufficient mechanical advantage through the gear reduction mechanisms.
2Device complexity
If a conventional steering system is used, then the structure is simple, but it does not provide sufficient mechanical advantage for heavy commercial vehicles
Solution Approach 1:
The patent employs a planetary gear set (130) where planet gears (134) are nested around a sun gear (132) and mesh with a ring gear (138). This nested configuration provides high mechanical advantage in a compact form factor. The globoidal worm drive (160) is then nested within the planetary gear output, adding another stage of mechanical advantage. This nested arrangement achieves the required force multiplication without excessive structural complexity.
Solution Approach 2:
The patent utilizes a globoidal worm drive (160) instead of a conventional linear or cylindrical worm gear. The globoidal shape of the worm and corresponding worm wheel provides superior mechanical advantage and load distribution. The curved, spherical geometry of the globoidal components allows for better contact area and force distribution, enhancing the mechanical advantage while maintaining a compact structure.
3Volume of stationary object
If the globoidal wormgearing is used, then sufficient mechanical advantage is provided within a compact package, but the device complexity increases
Solution Approach 1:
The patent combines the planetary gear set (130) and globoidal worm drive (160) into a single integrated steering mechanism. The electric motor, planetary gears, and worm drive are all coupled to common shafts (input shaft 110, output shaft 150) and housed within a single housing (102). This merging of multiple gear stages into one compact assembly provides the necessary mechanical advantage without occupying excessive space, as the components work together in a coordinated manner rather than as separate units.
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 electric power steering system effectively supplements driver torque, providing a mechanical robust and cost-effective solution for heavy commercial vehicles, enabling easier steering and reducing operational costs while maintaining safety and efficiency.
Implementation Method 1
The globoidal worm drive couples the input shaft to the output shaft such that the output shaft is rotatable with the input shaft via the globoidal worm drive
Implementation Method 2
A globoidal worm drive is arranged between the input shaft and the output shaft
Implementation Method 3
A planetary gear set includes a sun gear, a plurality of planet gears, a planet carrier, and a ring gear
Data Source
AI summary
An electric commercial vehicle power steering system includes an input shaft, an electric motor, and a planetary gear set, a drive coupling, and an output shaft. A first one of a sun gear, a planet carrier, and a ring gear of the planetary gear set is connected to and rotatable with a rotor of the electric motor, and a second one of the sun gear, the planet carrier, and the ring gear of the planetary gear set is connected to and rotatable with a first gear of the drive coupling. A second gear of the drive coupling is connected to and rotatable with the input shaft. A globoidal worm drive is arranged between the input shaft and the output shaft. The globoidal worm drive couples the input shaft to the output shaft such that the output shaft is rotatable with the input shaft via the globoidal worm drive.