Heavy Vehicle Steering Column Clutch Segmentation
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Solution Overview
Problem
Heavy vehicle steering systems face challenges with high cubic capacity hydraulic power steering systems, making manual operation difficult in fault conditions, and hydrostatic steering units suffer from unpredictable steering wheel spoke orientation due to fluid-dynamic leakage, leading to poor operator visibility and increased system costs in 'steer by wire' systems.
Innovation Solution
A steering system with a clutch mechanism between two portions of the steering column, allowing for manual steering and electronic assistance, featuring a hydrostatic steering unit with a small gerotor and electronic control unit for variable transmission ratio and zero position alignment, ensuring manageable operation in faults and enhanced comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hydrostatic steering unit with large cubic capacity is used, then the steering assistance is sufficient for heavy vehicles, but manual operation becomes extremely difficult in fault conditions
Solution Approach 1:
The steering column is divided into two separate portions (first portion and second portion) that can be mechanically disconnected. The first portion is connected to the steering wheel and the second portion to the hydrostatic steering unit, with a clutch mechanism enabling selective engagement. This segmentation allows the system to operate in two modes: assisted steering when the clutch is engaged, and manual steering when the clutch is disengaged, thereby resolving the contradiction between sufficient power assistance and manual operability.
2Power
If a hydrostatic steering unit is used, then steering assistance is provided, but the steering wheel spoke position becomes unpredictable due to fluid-dynamic leakage
Solution Approach 1:
An angular position sensor is implemented to detect the actual position of the steering wheel spokes. The electronic control unit receives this feedback signal and compares it with the desired zero position. When a deviation is detected (caused by fluid-dynamic leakage or other factors), the control unit automatically commands the hydrostatic steering unit to adjust the steering wheel position back to the correct zero alignment. This closed-loop feedback system ensures accurate and predictable spoke positioning while maintaining hydrostatic steering assistance.
3Manufacturing precision
If 'steer by wire' system is used to fix steering wheel position, then zero position accuracy is improved, but system cost and complexity increase due to required backups
Solution Approach 1:
The patent introduces an intermediary clutch mechanism that serves as a mechanical bridge between the steering wheel and the hydrostatic steering unit. This clutch acts as a fallback mediator: in normal operation, the hydrostatic system provides assistance with electronic feedback ensuring zero position accuracy; in fault conditions, the clutch can be disengaged to allow direct manual operation. This intermediary mechanical connection eliminates the need for complex backup systems typically required in pure 'steer by wire' configurations, reducing overall system complexity while maintaining position accuracy.
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
Enables safe manual steering in fault conditions, maintains vehicle manageability, and corrects steering wheel orientation, reducing system costs while providing settable maneuvering comfort and improved visibility.
Implementation Method 1
a hydrostatic steering unit, which facilitates the vehicle steering and makes the steering manoeuvre easier
Implementation Method 2
in the presence fluid-dynamic leakage of the hydraulic power steering system
Implementation Method 3
a clutch interposed between the first portion and the second portion, which clutch is normally open
Implementation Method 4
a second electric motor and a second angular position sensor is positioned on the second portion
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
A steering system (10) comprises a steering wheel (310), a steering column (30), provided with a first portion (31) associated to the steering wheel (310) and on which a first angular position sensor (316) is positioned, and a second portion (32), on which a second electric motor (325) and a second angular position sensor (326) are positioned, and a clutch (33) interposed between the first portion (31) and the second portion (32), the peculiarity of which is that the second portion (32) is associated to a hydrostatic steering unit (40) able to command a steering of a vehicle following a rotation imparted on the steering wheel (310) selectively by means of activating the second electric motor (325) when the clutch (33) is open or directly by means of the clutch (33) when the clutch is closed.