Engine Idle Speed Control via Learned Steering Angle
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Solution Overview
Problem
Existing methods for controlling engine idle speed in vehicles with hydraulic power steering systems are inaccurate due to reliance on steering wheel angle sensors, leading to increased fuel consumption as they fail to account for absolute steering wheel angles that cause engine load fluctuations.
Innovation Solution
The method involves learning and using an absolute steering wheel angle relative to the center position to adjust engine output, allowing for precise compensation of engine load variations during power steering operations, thereby reducing minimum engine idle speed and improving fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If engine idle speed is set higher to compensate for power steering load fluctuations, then engine load stability is improved, but fuel consumption increases
Solution Approach 1:
The system performs preliminary learning of the steering wheel angle sensor signal characteristics during vehicle operation to create a lookup table. This pre-computed data allows the engine control system to accurately predict and compensate for power steering load fluctuations without needing to continuously monitor hydraulic pressure, enabling more precise idle speed control that reduces fuel waste while maintaining stability.
Solution Approach 2:
The system uses feedback from the steering wheel angle sensor to continuously monitor steering wheel position and calculate power steering torque requirements. This feedback mechanism allows the engine control system to dynamically adjust idle speed based on actual power steering demands, preventing both fuel waste from excessive idle speed and instability from insufficient compensation.
2Device complexity
If steering wheel angle sensor signal is used to estimate power steering torque, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The steering wheel angle sensor serves dual purposes: it provides data for steering control and simultaneously enables power steering torque estimation for idle speed control. By utilizing the existing sensor's output (steering wheel angle) and combining it with pre-stored lookup table data, the system extracts torque information without requiring additional dedicated torque sensors, thereby maintaining low device complexity while achieving sufficient measurement precision.
Solution Approach 2:
The lookup table acts as an intermediary that translates steering wheel angle sensor data into power steering torque estimates. This intermediate data structure bridges the gap between the simple angle sensor and the complex torque calculation requirements, enabling accurate torque estimation without direct mechanical coupling or additional sensing elements.
3Measurement precision
If hydraulic pressure sensor is installed to directly monitor power steering load, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of directly measuring hydraulic pressure with a dedicated pressure sensor, the system creates a virtual copy of the pressure signal by calculating torque requirements from steering wheel angle data and stored lookup tables. This software-based approach replicates the information that would be provided by a pressure sensor without requiring the physical sensor hardware, thereby maintaining measurement precision while reducing device complexity and manufacturing cost.
Data Source
AI summary
A method is disclosed for controlling engine output in a vehicle having a hydraulic power steering system. The method may include, during an idle condition where an engine speed is set to an idle speed, adjusting engine output based on a learned absolute steering wheel angle to compensate for changes in engine load caused by operation of the hydraulic power steering system. The learned absolute steering wheel angle may be based on a steering wheel angle relative to a steering wheel position at vehicle startup and operating conditions from previous vehicle operation before the vehicle startup.