Vehicle Descent Control via Engine Braking Torque Monitoring
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Solution Overview
Problem
Existing vehicle descent control systems, such as hill descent control, may not be optimal for situations where vehicle speed is difficult to assess due to wheel slipping, freewheeling, or brake lockup, and engine braking alone may be insufficient on steep off-road terrain.
Innovation Solution
A method and system that monitor engine braking torque and compare it to a target torque, automatically applying or releasing brakes to maintain a desired engine braking torque, thereby controlling vehicle descent without driver input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If engine braking alone is used to control vehicle descent, then the system simplicity is maintained, but the control effectiveness is insufficient on steep off-road terrain
Solution Approach 1:
The patent combines engine braking with automatic brake control to form a hybrid descent control system. The controller monitors wheel speed and engine braking torque, then applies service brakes to supplement engine braking when needed, achieving reliable control on steep terrain while maintaining operational simplicity through automated coordination of both braking mechanisms
Solution Approach 2:
The braking system is designed to perform multiple functions: engine braking provides primary descent control under normal conditions, while automatic service brake application supplements control when engine braking is insufficient. The system universally handles various descent scenarios from gentle to steep terrain through a single integrated control strategy
2Extent of automation
If hill descent control systems apply brakes based on wheel speed detection, then automatic descent control is achieved, but the measurement accuracy deteriorates when wheels are slipping, freewheeling, or locked up
Solution Approach 1:
The patent introduces engine braking torque as an intermediary measurement parameter to indirectly assess vehicle descent rate and control needs. Instead of directly measuring wheel speed during unreliable conditions, the system monitors engine braking torque requirements and uses this information to control service brake application, providing accurate descent control even when wheel speed sensors are unreliable
Solution Approach 2:
The controller continuously monitors wheel speed, engine braking torque, and brake application status, then adjusts service brake pressure in real-time based on feedback from these parameters. This closed-loop feedback mechanism maintains accurate descent control by constantly comparing actual conditions with target performance and making corrective adjustments
3Speed
If driver manually applies brakes during descent, then the response time is fast, but the driver workload and potential for error increase
Solution Approach 1:
The descent control system operates autonomously by self-monitoring wheel speed and engine braking torque, then self-adjusting service brake application without driver intervention. The controller automatically applies and modulates brakes to maintain desired descent rate, eliminating the need for manual brake operation while providing consistent, error-free control throughout the descent
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 approach allows for automatic control of vehicle descent on steep terrain, ensuring stable speed without driver intervention, even when engine braking is insufficient, by dynamically adjusting brake application based on engine torque and vehicle conditions.
Implementation Method 1
Engine braking uses a compression stroke of the vehicle's internal combustion engine to dissipate energy transmitted to the engine from the vehicle's wheels through the vehicle's driveline and transmission
Implementation Method 2
a plurality of brakes for slowing rotation of the wheels
Data Source
AI summary
Vehicle descent is controlled in at least one implementation by comparing an engine braking torque to a target engine braking torque, and controlling one or more vehicle brakes to maintain the engine braking torque substantially at the target engine braking torque. The target engine braking torque may be varied as a function of one or more factors or conditions, such as accelerator position or brake application pressure.