Knuckle Steering Axle with Segmented Track Rods
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Solution Overview
Problem
Construction vehicles with knuckle steering systems experience high tire wear and stress in the drive train due to uneven steering angles during cornering, leading to increased operation and production costs, as well as undesirable sliding motions of the wheels.
Innovation Solution
The vehicle axle is designed with a knuckle steering system featuring a main steering cylinder connected to track rods, which are divided into coupling elements and supported by levers on the axle pipe, allowing for adjustable steering angles to minimize steering errors and reduce tire load and drive train stress through optimized kinematics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steering angle of the wheel outside the curve is increased to match the wheel inside the curve in a knuckle steering system, then both wheels can roll without lateral sliding, but the base of the vehicle increases and rocking inclination increases
Solution Approach 1:
The track rod is divided into multiple segments (first track rod segment, second track rod segment) connected by a coupling. This segmentation allows independent adjustment of steering angles for each wheel, enabling the outer wheel to have a smaller steering angle than the inner wheel, preventing lateral sliding while maintaining vehicle base dimensions.
Solution Approach 2:
The coupling is designed to be swingable relative to the wheel carrier, allowing the steering system to dynamically adjust the track rod length and steering angles during cornering. This dynamic adjustment enables optimal steering angle distribution between wheels without fixed geometric constraints.
2Device complexity
If a synchronous cylinder with continuous piston rod is used to transmit power to both wheels, then the steering system is simple, but high tire load and stress in the drive train occur during cornering
Solution Approach 1:
The single synchronous cylinder is segmented into two independent cylinders (first steering cylinder, second steering cylinder), each controlling one wheel independently. This allows different steering angles for inner and outer wheels during cornering, reducing tire load and stress while maintaining reasonable system complexity.
Solution Approach 2:
The coupling acts as an intermediary mechanism between the steering cylinders and wheel carriers, enabling independent steering angle control for each wheel while coordinating their motion during cornering operations.
3Ease of operation
If both swingable wheels are equally strongly turned in a knuckle steering system, then the steering system is simple to control, but both wheels are forced to unnatural paths causing sliding motion and wheel wear
Solution Approach 1:
The steering control is segmented into independent control for each wheel through separate cylinders and track rod segments, allowing the outer wheel to be turned at a smaller angle than the inner wheel during cornering, enabling both wheels to follow their natural rolling paths without sliding.
Solution Approach 2:
The steering angles of the wheels are changed as different parameters during cornering, with the outer wheel having a smaller steering angle parameter than the inner wheel. This parameter differentiation allows optimal path following for each wheel, reducing wear while maintaining ease of operation through coordinated control.
Data Source
AI summary
A vehicle having at least one axle (1) steerable via a knuckle steering system (4) which is designed with one main steering cylinder device (6) flexibly connected with track rods (8A, 8B). The track rods are in operative connection with wheel carriers (10A, 10B). A steering kinematics of the knuckle steering system between the main steering cylinder device and one wheel carrier (10A, 10B), is in flexible operative connection with a lever element (13A, 13B) rotatable around a fixed pivot (14A, 14B) in a manner that a steering angle error corresponding to a demanded steering angle is substantially minimized by a reduction of the angle of lock of the wheel (2A or 2B) currently outside the curve in relation to an angle of lock of the wheel (2B or 2A) currently inside the curve.