Hybrid Engine Start Control via Starter and Motor-Generator
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Solution Overview
Problem
Hybrid electric vehicles face challenges in effectively implementing various engine start modes due to differences in initial torque values and connection methods between starters and motor-generators, leading to inefficient fuel efficiency and potential damage from belt slipping.
Innovation Solution
A method that determines specific start conditions to selectively use a starter or motor-generator, including cold start, cooperative control, and restart modes, to minimize starter usage, prevent belt damage, and enhance fuel efficiency by engaging and disengaging the starter and motor-generator based on engine RPM and battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the starter is used to start the engine, then the engine can be reliably started with high initial torque, but the starter wear increases and durability decreases
Solution Approach 1:
The patent combines two starting systems (starter and motor-generator) into a hybrid starting system. The motor-generator is connected to the engine crankshaft via a belt, allowing it to function as an auxiliary starter. This merging enables the system to share the starting load, reducing wear on the traditional starter while maintaining reliable engine starting capability.
2Loss of energy
If the motor-generator is used to start the engine, then fuel efficiency is improved and starter wear is reduced, but belt slipping may occur causing potential damage
Solution Approach 1:
The patent implements dynamic control of the motor-generator starting system. The control unit monitors engine cranking speed and adjusts the motor-generator output accordingly. By dynamically adjusting the driving force based on real-time engine conditions, the system prevents excessive belt load that could cause slipping, while still utilizing the motor-generator's high efficiency benefits.
Solution Approach 2:
The system incorporates feedback control where the control unit continuously monitors engine cranking speed and adjusts the motor-generator operation accordingly. This feedback mechanism ensures the belt transmission operates within safe limits, preventing slipping and damage while optimizing the motor-generator's contribution to engine starting.
3Adaptability or versatility
If the starter is used frequently for engine starting, then various start modes can be implemented, but the starter wear increases and maintenance requirements increase
Solution Approach 1:
The motor-generator is designed to serve multiple functions: it acts as a starter motor for engine starting, a generator for electrical power generation, and an auxiliary drive for engine cranking. This multi-functionality reduces reliance on the traditional starter, decreasing its usage frequency and wear, while maintaining the vehicle's ability to implement various starting modes including cold start, warm start, and emergency starting scenarios.
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
This method reduces starter wear, minimizes motor-generator high-torque usage, and stabilizes the idle-stop and go mode, thereby enhancing fuel efficiency and durability by optimizing engine start processes.
Implementation Method 1
a motor-generator connected to the engine by a belt to start the engine or produce electricity
Implementation Method 2
a starter connected to the engine by a gear to start the engine
Implementation Method 3
a motor-generator connected to the engine by a belt
Implementation Method 4
a starter connected to the engine by a gear
Data Source
AI summary
A method for starting an engine for a hybrid electric vehicle that includes a starter connected to the engine by a gear to start the engine and a motor-generator connected to the engine by a belt to start the engine or produce electricity include determining whether a start signal is input, determining whether a predetermined cold start condition is satisfied when it is determined that the start signal is input, starting the engine by use of the starter in a predetermined cold start mode when the cold start condition is satisfied, determining whether a predetermined cooperative control start condition is satisfied when the cold start condition is not satisfied, and starting the engine by use of the starter and the motor-generator in a predetermined cooperative control start mode when the cooperative control start condition is satisfied.