Hybrid Powertrain Segmented Transmission for Engine Speed Utilization

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Solution Overview

Problem

Hybrid drive trains for motor vehicles do not fully exploit the high continuous traction and high maximum speed capabilities of internal combustion engines, particularly at low speeds and high speeds, due to limitations in electric motor performance.

Innovation Solution

The drive train is enhanced by allowing the internal combustion engine and electric motor to be coupled to the vehicle output via optimized transmission stages, with the electric generator remaining directly coupled to the crankshaft, and the electric motor having its own independent coupling and transmission stage, enabling better utilization of the engine's properties across various speed ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the electric motor is used as the primary drive in a serial hybrid configuration, then electrical efficiency and low-speed torque are improved, but the internal combustion engine's high-speed capability and continuous traction are not fully exploited

Engineering Contradiction:
Improveelectrical efficiencyVSAvoidengine capability utilization
Core Design Contradiction:
Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent divides the power transmission path into separate segments: the internal combustion engine connects to the output via its own transmission stage, and the electric motor connects to the output via a separate transmission stage. This segmentation allows each power source to operate independently in its optimal range, resolving the contradiction between electrical efficiency and engine capability utilization.

Inventive Principle:
Principle #1Segmentation

2Force

If the electric motor is directly coupled to the output, then low-speed torque is improved, but high-speed performance is limited by the electric motor's speed limitation

Engineering Contradiction:
Improvelow-speed torqueVSAvoidmaximum speed
Core Design Contradiction:
ForceVSSpeed

Solution Approach 1:

The patent introduces an intermediary transmission stage between the electric motor and the output. This transmission stage acts as a mediator that can decouple the electric motor from the output at high speeds, allowing the internal combustion engine to take over and achieve high-speed performance while the electric motor maintains its low-speed torque advantage.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the internal combustion engine is directly coupled to the output, then high-speed performance and continuous traction are improved, but low-speed electrical efficiency is reduced

Engineering Contradiction:
Improvecontinuous tractionVSAvoidelectrical efficiency
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements a dynamic transmission system where the internal combustion engine's connection to the output can be selectively engaged or disengaged based on operating conditions. This dynamic configuration allows the system to switch between engine-driven mode (for high-speed performance) and electric motor-driven mode (for low-speed electrical efficiency), resolving the contradiction between continuous traction and electrical efficiency.

Inventive Principle:
Principle #15Dynamics

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 configuration allows for improved utilization of the internal combustion engine's high speed and torque capabilities, optimizing traction and fuel efficiency by decoupling the electric motor at high speeds and using the engine's speed range effectively, thus overcoming previous limitations in traction and speed.

Implementation Method 1

a first electrical machine that primarily works as a generator, the rotor of which is connected to an output shaft of the internal combustion engine and whose electrical output is connected to an electrical energy storage device

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a second electrical machine that primarily operates as a motor, the electrical input of which is connected to the electrical energy storage device

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP2289751B1Hybrid powertrain for a motor vehicle and method for operating same
Publication Date: 2018.05.23 VOLKSWAGEN AG
  • EP2289751B1 patent drawingFigure 1~4
  • EP2289751B1 patent drawingFigure 5~7
  • EP2289751B1 patent drawingFigure 8~10

AI summary

The hybrid drive strand has an electrical machine (12) coupled alternatively over a translation stage (i1) or over another translation stage (i2) with a drive (20). Another electrical machine (16) is coupled alternatively over a third translation stage (i3) and independently from former electrical machine with the drive. An independent claim is also included for a method for operating drive strand.