Isochronous Torque Control for Agricultural Harvester Engines
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Solution Overview
Problem
Agricultural harvesters with internal combustion engines face operational issues at lower power settings and engine rpm, where sudden load increases lead to abrupt torque rises, causing the engine to appear as if it 'runs out of power, and traditional torque curves compromise fuel efficiency at light loads.
Innovation Solution
Implementing a method to operate the IC engine with a base torque curve in normal mode and a boost torque curve when needed, using a hydrostatic or hydromechanical transmission system with an electrical processing circuit to manage fuel injectors, allowing for isochronous power output and a power bulge above rated power, optimizing engine performance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional torque curves are used at lower power settings, then the engine can handle sudden load increases, but the torque rises abruptly causing the engine to appear as if it runs out of power
Solution Approach 1:
The system dynamically switches between different torque curve characteristics (isochronous governor curve for smooth operation vs. torque limit curve for maximum power) based on operating conditions. The control system adjusts the torque curve shape in real-time to match load requirements, transitioning smoothly between operational modes to maintain both reliability and operational smoothness.
Solution Approach 2:
The invention changes the torque curve parameters (governor curve shape and torque limit curve) based on engine operating points. At lower power settings, the system modifies the torque rise characteristics to prevent abrupt transitions, while at higher power settings it allows for maximum torque rise to handle sudden loads, thus adapting parameters to operational needs.
2Ease of operation
If the governor reduces torque rise as the engine approaches rated engine rpm, then the engine operates smoothly, but the operator perceives a sudden loss of power when encountering step increases in load
Solution Approach 1:
The control system prepares for potential load increases by pre-positioning the engine operating point and torque curve characteristics. Before a step increase in load occurs, the system ensures the engine is ready to transition smoothly into the torque limit region, preventing the perception of power loss by anticipating and preparing for the load change.
Solution Approach 2:
The system continuously monitors engine operating conditions and adjusts torque delivery in real-time based on feedback from sensors. When approaching rated rpm or detecting conditions that may lead to sudden load increases, the control system modifies torque rise characteristics to maintain both smooth operation and perceived power availability through active feedback control.
3Ease of operation
If the torque curve is shaped with steep torque rise at lower engine rpm, then the engine feels responsive and powerful, but torque rise at lower engine rpm down to peak torque is reduced
Solution Approach 1:
The invention applies different torque curve characteristics to different engine operating regions. In the lower rpm region below peak torque, the system maintains gentler torque rise to preserve actual torque availability, while in the region from peak torque to rated rpm, it implements steeper torque rise to provide the sensation of power and responsiveness. This local differentiation of torque characteristics resolves the contradiction between perceived responsiveness and actual torque availability.
Data Source
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AI summary
A method of operating an internal combustion engine (12) in an agricultural harvester (10) includes the steps of operating the engine (12) in a normal mode with a base torque curve (42) as a function of engine operating speed and engine power output, the base torque curve (42) being generally isochronous at a rated operating speed over a power output range terminating at a rated power output; and operating the engine (12) in a boost mode with a boost torque curve (48) when a power boost is required above the rated power output, the boost torque curve (48) having a power output which is above the base torque curve over a predefined range of the operating speed.