Engine Torque Limiting for Fuel-Saving Hybrid Loaders
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Solution Overview
Problem
Existing machines using internal combustion engines for both ground and implement propulsion face inefficiencies in fuel consumption due to the full torque range being utilized across varying torque demands, leading to over-fuelling and increased fuel usage, especially in implement and hybrid modes where torque requirements are high but brief.
Innovation Solution
Implementing a torque limit curve that restricts engine torque availability based on speed thresholds, allowing gradual increase or removal of torque limits to match demand, thereby reducing engine speed and fuel consumption without significantly impacting machine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine torque curve is sized for all applications and maximum torque is maintained, then torque availability is improved, but fuel consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the torque limit adjustable and speed-dependent rather than fixed. The torque limiter dynamically adapts the maximum torque based on current engine speed and operating conditions, allowing the system to transition between different torque availability states as needed.
Solution Approach 2:
The patent changes the parameter of torque availability based on engine speed thresholds. By monitoring engine speed and adjusting the torque limit parameter accordingly, the system optimizes the balance between power delivery and fuel consumption across different operating regimes.
2Use of energy by moving object
If torque limit is reduced to save fuel during brief high torque demands, then fuel consumption is improved, but torque availability deteriorates
Solution Approach 1:
The patent applies partial action by implementing torque limits that are sufficient for most operating conditions but not necessarily maximum at all times. The torque limiter allows reduced torque during brief, non-critical demand periods while maintaining adequate torque availability when truly needed, accepting partial limitation to achieve overall fuel savings.
Solution Approach 2:
The system applies preliminary anti-action by preemptively limiting torque before excessive fuel consumption occurs. The torque limiter anticipates that maintaining maximum torque during brief high-demand periods would result in disproportionate fuel consumption, and applies limiting action in advance to prevent this inefficiency.
3Power
If full torque is available during implement propulsion mode, then implement performance is improved, but fuel consumption increases
Solution Approach 1:
The torque limiter dynamically adjusts torque availability based on real-time engine speed monitoring during implement propulsion mode. The system transitions between torque-limited and full-torque states depending on whether the engine speed remains above or drops below the threshold, optimizing the balance between implement performance and fuel consumption.
Solution Approach 2:
The system uses feedback from engine speed monitoring to continuously adjust torque availability. The torque limiter receives feedback about current engine operating conditions and modifies torque delivery accordingly, creating a closed-loop control system that optimizes fuel efficiency while maintaining adequate implement performance.
Data Source
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AI summary
A method of reducing fuel consumption in a machine with an internal combustion engine. The machine has a hybrid mode in which the engine is used for simultaneous ground propulsion via a torque convertor and hydraulic implement propulsion via a hydraulic pump. The engine controller uses a first engine map that defines primary operating constraints. The method comprises: obtaining an initial torque limit from a torque limit profile providing operating constraints that fall within the primary operating constraints. The method further comprises: implementing a torque limit that corresponds to the initial torque limit value such that in an event that a torque demand exceeds the torque limit then the engine speed will drop below the desired engine speed. The method further comprises, in an event that torque converter speed ratio between engine and ground propulsion drops below a speed ratio threshold, removing the torque limit profile and reverting to primary operating constraints.