Utility Vehicle Brake Steering With Inner-Wheel Torque Split
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Solution Overview
Problem
The increasing size of agricultural machinery and stricter exhaust gas emission requirements limit the steering angle and turning radius of utility vehicles, leading to insufficient steering brake capability, especially when only one side of the rear axle is braked during steering, resulting in inefficient soil compaction and power transfer.
Innovation Solution
A method and driveline system for a four-wheel drive utility vehicle that applies service brakes to both front and rear wheels on the inside of a turn and adjusts torque distribution between axles via a controlled clutch arrangement, with independently operable service and parking brakes, to enhance steering capability and reduce soil damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tyre size is increased to reduce soil compaction, then soil compaction is reduced, but steering angle and turning radius are limited
Solution Approach 1:
The patent applies dynamic torque distribution through a controlled clutch arrangement that continuously adjusts the torque share between front and rear axles during steering braking. This dynamic adaptation allows the vehicle to compensate for the limited steering angle caused by large tyre sizes, effectively resolving the contradiction between reduced soil compaction and maintained steering capability.
2Ease of operation
If steering brake capability is increased by braking only one side of the rear axle, then turning radius is reduced, but braking force utilization is insufficient
Solution Approach 1:
The patent segments the braking system into four independently controllable service brakes (left and right front, left and right rear) with individual brake circuits. This segmentation allows selective application of brakes on specific wheels, enabling effective steering braking while optimizing the utilization of available braking force across all four wheels through coordinated control.
Solution Approach 2:
The patent changes the parameter of brake force distribution by applying service brakes to both front and rear wheels on the inside of the turn simultaneously. This parameter change optimizes the utilization of braking force by engaging all available brakes on the inner side, thereby improving both turning radius and braking force utilization.
3Device complexity
If torque distribution is fixed between front and rear axles, then system complexity is reduced, but steering braking efficiency is insufficient
Solution Approach 1:
The patent implements a controlled clutch arrangement that dynamically adjusts torque distribution between front and rear axles based on steering braking conditions. This dynamic torque distribution optimizes steering braking efficiency by providing enhanced braking force to the inner wheels while maintaining manageable system complexity through a well-defined control strategy.
4Power
If front axle load is increased by high vehicle weight, then power transfer to ground is improved, but inner front wheel movement during steering braking is restricted
Solution Approach 1:
The patent applies preliminary action by activating service brakes on the inner front wheel before and during the steering maneuver. This preliminary braking action counteracts the restriction caused by high front axle load, enabling the inner front wheel to move inwards effectively during steering braking while maintaining good power transfer to the ground.
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
This solution allows for tighter turns, reduced soil damage, and improved power transfer efficiency by adapting torque distribution and applying proportional braking forces, enhancing the vehicle's maneuverability and soil conservation.
Implementation Method 1
applying the service brakes of the front and rear wheels on the inside of the turn
Implementation Method 2
adjusting the clutch arrangement to adapt the share of the available torque between the front and rear axles
Data Source
AI summary
A method of brake steering in a four-wheel drive utility vehicle having a driven front axle carrying at least two front wheels, a driven rear axle carrying at least two rear wheels, a powertrain delivering torque to the front and rear axles via a connecting shaft, a controlled clutch arrangement in the connecting shaft operable to vary the distribution of delivered torque between the front and rear axles, and independently operable service brakes on each of the front and rear wheels. The method comprises, on the vehicle entering a turn, applying the service brakes of the front and rear wheels on the inside of the turn and adjusting the clutch arrangement to adapt the share of the available torque between the front and rear axles. Additional braking force may be applied from independently operable park brakes on the rear wheels in inverse relationship to the level of service brake force applied.