Hybrid Vehicle Engine Control for Noise and Fuel Efficiency
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Solution Overview
Problem
Hybrid vehicles using engines and rotary machines face a decrease in fuel efficiency when the engine operating point shifts outside a predetermined optimal fuel-efficiency region, leading to increased noise and reduced performance.
Innovation Solution
A control device that adjusts the engine operating point to remain on the optimal fuel-efficiency line by compensating with the rotary machine's output, while also considering the state of charge of the power storage device and selected travel modes to minimize fuel efficiency loss and noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the engine operating point is shifted to an operating point separated from the optimal fuel-efficiency operating line outside the noise region, then noise is reduced, but fuel efficiency decreases
Solution Approach 1:
The patent introduces a rotary machine as an intermediary device between the engine and the wheels. When the engine operating point needs to be shifted from the optimal fuel-efficiency line to reduce noise, the rotary machine compensates for the output difference, thereby maintaining overall vehicle performance while allowing the engine to operate in a quieter region. This mediator approach resolves the contradiction by decoupling the engine's noise reduction from fuel efficiency loss.
Solution Approach 2:
The patent dynamically changes the engine operating parameters (rotation speed and output) based on noise level detection. When noise exceeds a threshold, the system shifts the operating point to a lower noise region while using the rotary machine to maintain the required vehicle output. This parameter change strategy allows the system to prioritize noise reduction while compensating for fuel efficiency through the rotary machine's output adjustment.
2Loss of energy
If the engine operating point is kept on the optimal fuel-efficiency operating line, then fuel efficiency is improved, but noise increases when the operating point is in the predetermined region
Solution Approach 1:
The patent implements a dynamic control system that continuously monitors both the engine operating point and noise levels. The system can dynamically switch between two strategies: maintaining the optimal fuel-efficiency operating line when noise is acceptable, and shifting to a noise-reduced operating point when noise exceeds thresholds. This dynamic adaptation allows the system to optimize for fuel efficiency during normal operation while automatically prioritizing noise reduction when necessary.
Solution Approach 2:
The patent employs a feedback mechanism where noise levels are continuously detected and used to adjust the engine operating point. When the operating point falls within the noise generation region, the feedback signal triggers a shift to a quieter operating point, with the rotary machine compensating for any output loss. This closed-loop feedback system resolves the contradiction by allowing the engine to deviate from the optimal fuel-efficiency line only when and where noise becomes problematic.
3Object-affected harmful factors
If the engine operating point is shifted outside the noise generation region, then noise is reduced, but the operating point may become further from the optimal fuel-efficiency line increasing fuel consumption
Solution Approach 1:
The rotary machine serves as a mediator that bridges the gap between noise reduction and fuel efficiency. When the engine operating point is shifted outside the noise generation region, potentially farther from the optimal fuel-efficiency line, the rotary machine compensates for the output difference, ensuring that the vehicle's overall performance requirements are met while allowing the engine to operate in a quieter region.
Solution Approach 2:
The patent creates an asymmetric solution where the rotary machine handles the asymmetry in the operating point shift. Instead of requiring the engine to maintain optimal fuel efficiency while reducing noise, the system allows asymmetric operation of the engine (prioritizing noise reduction) while the rotary machine provides the symmetric compensation needed to maintain overall system performance and minimize fuel consumption.
Data Source
AI summary
A control device for a hybrid vehicle includes an engine operating point control unit that shifts an engine operating point to an engine operating point on an optimal fuel-efficiency operating line outside a predetermined noise generation region in which combustion sounds of an engine become noise when the engine operating point is in the noise generation region. Accordingly, when the engine operating point is in the noise generation region, the engine operating point control unit shifts the engine operating point to an engine operating point on the optimal fuel-efficiency operating line outside the noise generation region. As a result, since the engine operating point is not separated from the optimal fuel-efficiency operating line even when the engine operating point departs from the noise generation region, it is possible to curb a decrease in fuel efficiency.