Hybrid Vehicle Starter-Generator System with Planetary Gear
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Solution Overview
Problem
The existing starting and generating systems for hybrid vehicles face challenges with controllability and efficiency due to the use of a belt transmission method, which leads to deterioration in transmission efficiency and layout limitations when a large-capacity motor is required, especially in large-sized vehicles.
Innovation Solution
A starting and generating system that employs a planetary gear mechanism to connect the engine, starter-generator, and motor-generator, along with a controller to manage the operation of brakes and motors, allowing for efficient power transmission and mode control between engine starting, series driving, and general traveling modes, using two small-capacity motors instead of a single large-capacity motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single large-capacity motor is used to meet the power requirements of large-sized vehicles, then the power output is sufficient, but the layout becomes limited and the load on the engine shaft increases
Solution Approach 1:
The patent divides a single large-capacity motor into two small-capacity motors (starter-generator and motor-generator). Each motor handles specific functions: the starter-generator starts the engine and generates electricity, while the motor-generator assists in starting and generates electricity during series driving mode. This segmentation reduces the size and layout constraints of individual motors while maintaining total power output capability.
Solution Approach 2:
Both the starter-generator and motor-generator are designed to perform multiple functions: engine starting, electricity generation during series mode, and potential assistance during general traveling mode. This multi-functionality allows two smaller motors to replace one large motor, improving layout flexibility while meeting all power requirements across different operating modes.
2Power
If a single large-capacity motor is used, then the power requirement is met, but the load applied to the engine shaft increases
Solution Approach 1:
The patent segments the load-bearing function across two motors with different characteristics. The starter-generator, connected through a planetary gear mechanism, provides high-torque starting capability with reduced shaft load during engine cranking. The motor-generator supplements starting torque and provides continuous power during series mode, distributing the overall load demand and preventing excessive concentrated load on the engine shaft.
Solution Approach 2:
The system dynamically switches between different motor configurations and engagement states. The engine clutch selectively engages or disengages the motor-generator based on operating mode, and the planetary gear mechanism adjusts torque transmission ratios. This dynamic control optimizes the distribution of load between the two motors and the engine shaft, preventing excessive load concentration.
3Device complexity
If a belt transmission method is used to connect the starter-generator and engine, then the structure is simple, but the transmission efficiency deteriorates and controllability is reduced
Solution Approach 1:
The patent replaces the belt transmission mechanical system with a direct connection or alternative transmission mechanism between the starter-generator and the engine. This substitution eliminates belt-related energy losses from slip and tension variations, improving transmission efficiency while maintaining structural simplicity through the direct coupling enabled by the planetary gear mechanism.
4Device complexity
If a belt transmission method is used, then the structure is simple, but the controllability deteriorates
Solution Approach 1:
The patent replaces the passive belt transmission system with an actively controllable connection system. The engine clutch provides precise control over power transmission between the motor-generator and engine, enabling dynamic engagement and disengagement based on operating mode. The planetary gear mechanism also provides controllable torque distribution, significantly improving system controllability compared to passive belt transmission.
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 solution enhances controllability and efficiency by effectively managing power transmission and reducing material and production costs, allowing for easier layout configuration and reduced development costs, while addressing the limitations of using a single large-capacity motor.
Implementation Method 1
a planetary gear mechanism which connects the engine, the starter-generator, and the motor-generator to transmit rotational force between the engine, the starter-generator, and the motor-generator
Implementation Method 2
a first brake and a second brake configured to selectively operate rotating elements, and connected to the starter-generator and the motor-generator among the rotating elements of the planetary gear mechanism, as a fixed element
Data Source
AI summary
A starting and generating system for a hybrid vehicle is provided. The system includes a starter-generator which transmits rotational force to the engine to start the engine when the starter-generator is operated as a motor, and is operated as a generator by receiving rotational force of the engine. A motor-generator is operated as a generator by receiving rotational force of the engine and a planetary gear mechanism connects the engine, the starter-generator, and the motor-generator to transmit rotational force between the engine, the starter-generator, and the motor-generator. Additionally, a first brake and a second brake selectively operate rotating elements, which are connected to the starter-generator and the motor-generator among the rotating elements of the planetary gear mechanism, as a fixed element. A controller specifically operates the starter-generator, the motor-generator, the first brake, and the second brake.