Hybrid Engine Idle Speed Optimization via MGU Load Monitoring
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Solution Overview
Problem
Hybrid electric vehicles (HEVs) with auto stop/auto start functionality face inefficiencies in engine idle management, leading to unnecessary fuel consumption and operational instability under varying conditions.
Innovation Solution
A method and system that utilize a controller with an algorithm to optimize engine idle speed by monitoring and adjusting the motor generator unit (MGU) speed based on electrical load, temperature, and efficiency requirements, ensuring stable operation and minimizing fuel usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine idle speed is reduced to save fuel, then fuel consumption decreases, but the MGU may not meet electrical load requirements and engine stability deteriorates
Solution Approach 1:
The controller proactively adjusts engine idle speed based on predicted electrical load requirements before the MGU actually needs the power. By monitoring parameters like air conditioning compressor operation, heater demands, and accessory loads, the system preemptively increases idle speed to ensure the MGU can meet upcoming electrical demands without compromising fuel efficiency during low-load periods
Solution Approach 2:
The engine idle speed is made dynamically adjustable rather than fixed, allowing real-time optimization based on actual electrical load conditions. The controller continuously monitors MGU load requirements and adjusts idle speed accordingly, creating a dynamic balance between fuel consumption and electrical power availability
2Reliability
If the engine idle speed is increased to meet electrical load requirements, then MGU capacity improves, but fuel consumption increases and thermal efficiency deteriorates
Solution Approach 1:
The system changes the operating parameters of the MGU by adjusting its speed and load based on actual electrical demands. Rather than maintaining a fixed high idle speed, the MGU operates at optimized speed points that match actual load requirements, reducing unnecessary fuel consumption while ensuring adequate power availability when needed
Solution Approach 2:
The controller autonomously manages the balance between engine idle speed and MGU electrical output by monitoring system conditions and making real-time adjustments without external intervention, optimizing fuel efficiency while ensuring electrical load requirements are met
3Use of energy by moving object
If the engine idle speed is reduced for fuel efficiency, then fuel consumption decreases, but noise, vibration, and harshness (NVH) performance deteriorates
Solution Approach 1:
The controller preemptively adjusts idle speed to account for upcoming electrical load requirements, allowing the engine to operate at lower, quieter speeds during periods of low demand while ensuring adequate power is available when loads increase, thus reducing overall NVH exposure
4Use of energy by moving object
If the MGU temperature increases to improve electrical efficiency, then electrical efficiency improves, but the MGU may become incapable of meeting load requirements due to thermal de-rating
Solution Approach 1:
The system implements continuous feedback monitoring of MGU temperature, using this information to dynamically adjust engine idle speed and MGU operating parameters. When temperature approaches de-rating thresholds, the controller preemptively adjusts operations to prevent capacity loss, ensuring reliable power delivery while maximizing electrical efficiency during optimal temperature ranges
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively optimizes engine idle speed to meet electrical demands while enhancing thermal and electrical efficiency, noise reduction, and stability, thereby reducing fuel consumption and preventing MGU incapacity due to overheating.
Implementation Method 1
a high-voltage (HV) motor generator unit (MGU) adapted to assist the automatic starting of the engine
Implementation Method 2
the MGU operates at a speed sufficient to meet onboard vehicle electrical requirements
Data Source
AI summary
A method for optimizing an engine idle speed in a vehicle having an engine, a motor generator unit (MGU), and an energy storage system (ESS) includes determining vehicle operating values, including at least one of: an electrical load of an accessory, a torque capacity of the MGU, a temperature of the MGU, an efficiency of the MGU, and a state of charge (SOC) of the ESS. The method also includes calculating a set of engine speed values using the set of vehicle operating values, and using a controller to command the engine idle speed as a function of the set of engine speed values. A vehicle includes an engine, an ESS, an MGU, and a controller having an algorithm adapted for optimizing an idle speed of the engine as set forth above.