Hill Descent Control Modulating Braking Torque for Vehicle Acceleration
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Solution Overview
Problem
Existing hill descent control systems for vehicles fail to maintain a constant speed during steep gradients without relying on engine braking, which can be insufficient in certain conditions.
Innovation Solution
A vehicle hill descent control system that uses an electronic control unit with sensors and a braking control system to manage engine torque and braking torque, operating the engine at idle and adjusting braking torque based on accelerator pedal position to maintain a desired speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engine braking is used to control vehicle speed during hill descent, then speed control is achieved, but the braking force becomes insufficient on steep gradients
Solution Approach 1:
The patent combines engine braking with service brake systems to create a hybrid hill descent control system. The electronic control unit coordinates both the engine (maintaining idle or elevated RPM for braking effect) and the service brakes (providing additional deceleration force), merging two braking mechanisms to achieve sufficient and reliable speed control on steep gradients where either system alone would be inadequate.
2Reliability
If braking torque is increased to control speed on steep gradients, then speed control reliability improves, but the ability to accelerate when needed deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of braking torque based on real-time driver input through the accelerator pedal. The electronic control unit continuously monitors accelerator pedal position and dynamically modulates service brake torque accordingly. When the driver presses the accelerator, the system reduces braking torque to enable acceleration, while maintaining the capability for reliable speed control when the accelerator is released, thus adapting the braking force to varying operational requirements.
3Stability of the object's composition
If the accelerator pedal is disconnected from the engine to maintain idle torque, then speed control stability improves, but the driver's ability to control vehicle acceleration deteriorates
Solution Approach 1:
The patent introduces the service brake system as an intermediary mechanism between the driver's accelerator pedal input and the actual vehicle acceleration. When the driver presses the accelerator during hill descent, the electronic control unit interprets this as a speed increase request and responds by reducing service brake torque, rather than directly increasing engine torque. This intermediary approach maintains engine idle stability while still providing driver-controlled acceleration through brake modulation.
Data Source
AI summary
A vehicle hill descent control system and method for controlling a vehicle during a hill descent receives inputs from an accelerator pedal position sensor and a brake pedal sensor. The method controls the engine drivetrain system to engine idling and controls the braking control system to maintain vehicle speed by increasing braking torque to minimize or offset a vehicle speed increase due to gravity. In vehicle hill descent mode, when a vehicle user actuates the accelerator pedal, the engine idling does not change. Instead, the electronic control unit operates to decrease braking torque so the vehicle speed is increased.