Vehicle Control Device for Dynamic Traction Brake Adjustment
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Solution Overview
Problem
Conventional vehicle traction control systems struggle to maintain smooth travel on off-road or sloping surfaces, leading to excessive acceleration slips and vehicle stalling, as they fail to match traction control (TRC) with the actual vehicle travel state, thereby deteriorating ground-covering properties.
Innovation Solution
A vehicle control device that includes a target speed setting mechanism for traction brake threshold speed and a TRC system generating braking force when wheel speed exceeds the target speed, with a brake control amount correction mechanism adjusting the braking force based on the degree of stall prevention request, vehicle body speed, road-surface resistance, and accelerator opening rate to better match the vehicle travel state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If larger braking force is applied to improve ground-covering properties when auxiliary transmission is in low gear, then ground-covering properties are improved, but vehicle stalls and ground-covering properties deteriorate
Solution Approach 1:
The patent applies dynamics by making the tolerable slip value variable rather than fixed. The control device dynamically adjusts the tolerable slip based on detected wheel acceleration, allowing the TRC control to adapt to changing vehicle states. This prevents excessive braking force application that would cause stalling while maintaining effective traction control when needed.
Solution Approach 2:
The patent changes the parameter of tolerable slip from a constant value to a dynamically adjusted value based on wheel acceleration detection. By monitoring wheel acceleration and comparing it against threshold values, the system adjusts the tolerable slip parameter to prevent vehicle stalling while maintaining effective traction control.
2Object-generated harmful factors
If tolerable slip is reduced to execute idling inhibitory control, then acceleration slip is inhibited, but vehicle cannot smoothly travel on off road or sloping road
Solution Approach 1:
The system dynamically adjusts the tolerable slip threshold based on wheel acceleration detection rather than using a fixed reduced value. This allows the TRC control to be gentle when wheel acceleration is low (enabling smooth travel) while still providing effective slip inhibition when wheel acceleration indicates actual slip conditions.
Solution Approach 2:
The patent implements feedback control by continuously detecting wheel acceleration and using this information to adjust the tolerable slip value. The system monitors the actual wheel acceleration and compares it against thresholds to determine appropriate TRC control intensity, creating a closed-loop control system that adapts to real-time vehicle conditions.
3Stability of the object's composition
If TRC is executed with fixed tolerable slip value, then acceleration slip control is consistent, but TRC not matched to actual travel state deteriorates ground-covering properties
Solution Approach 1:
The patent transforms the static tolerable slip value into a dynamic parameter that changes based on wheel acceleration detection. This allows TRC control to be matched to the actual travel state while maintaining consistency through systematic threshold-based adjustment rather than arbitrary changes.
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 system improves ground-covering properties by adjusting braking force according to the vehicle's travel state, preventing excessive braking and stalling, and enhancing safety and control during off-road travel.
Implementation Method 1
a TRC means for generating braking force with the service brake when the wheel speed exceeds the target speed
Implementation Method 2
a brake control amount correction means for determining a degree of a stall prevention request of the vehicle, and reducing a brake control amount for generation of braking force by the TRC
Data Source
AI summary
A vehicle control device corrects the amount of brake control according to the degree of stall prevention requests such that the brake control amount is matched to a travel state. For example, when the vehicle body speed is low, the vehicle body is often traveling a road surface that is difficult to travel, and the degree of stall prevention requests is small. In such cases, the vehicle control device exhibits LSD effects and increases ground-covering properties by executing vehicle wheel slip control based on stronger brake control, while increasing safety properties by better enabling generation of deceleration. Then, as the vehicle body speed increases, because it is conceivable that the vehicle body is leaving a place that is difficult to travel and the degree of stall prevention requests is high, the vehicle control device executes switching such that brake control is lowered.