Hybrid Drive Transmission Flywheel Start to Prevent Torque Drop

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Solution Overview

Problem

Hybrid drive systems face challenges in efficiently starting the internal combustion engine while minimizing energy consumption and reducing abrupt torque drops, leading to jerking sensations in vehicles, due to the high energy requirements for starting the engine and the need for permanent electrical power availability.

Innovation Solution

The implementation of a hybrid drive transmission unit with a torsion damping unit and an intermediate clutch, allowing the electric motor to store kinetic energy and transfer it to the flywheel, which then brings the internal combustion engine to a self-sustaining speed, while intelligent switching of partial transmission clutches manages torque to avoid abrupt drops and ensures smooth starting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the internal combustion engine uses its own starter generator to start, then the engine can be started reliably, but a very high amount of energy is required and permanently available electrical power is reduced

Engineering Contradiction:
Improveengine starting reliabilityVSAvoidenergy consumption for starting
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary action by storing kinetic energy in the flywheel during electric driving mode before the engine needs to start. The flywheel accumulates rotational energy that can be rapidly transferred to the crankshaft via the intermediate clutch, eliminating the need for a high-power starter generator and reducing peak energy demands on the electrical system.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The intermediate clutch acts as an intermediary mechanism between the flywheel and the crankshaft. It enables direct mechanical coupling to transfer kinetic energy from the flywheel to the engine during starting, while allowing decoupling during normal operation. This intermediary component resolves the contradiction by providing an alternative energy transfer path that bypasses the electrical starter generator system.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the electric motor is used to start the internal combustion engine, then energy storage requirements are reduced, but an abrupt drop in power on the output shaft and unwanted jerking occurs

Engineering Contradiction:
Improveelectrical power availabilityVSAvoidtorque drop and vehicle jerking
Core Design Contradiction:
Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The system prepares in advance by accelerating the flywheel to high rotational speed during electric driving operation, storing the kinetic energy needed for engine starting. When starting is required, the pre-stored energy is immediately transferred to the crankshaft through the intermediate clutch, enabling smooth engine startup without power drops or jerking motions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The intermediate clutch serves as a controlled intermediary that manages the power transfer from the flywheel to the crankshaft. By controlling the engagement timing and slip characteristics of this clutch, the system smoothly transfers kinetic energy without causing abrupt torque changes on the output shaft, thereby eliminating vehicle jerking while maintaining electrical power availability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Speed

If the intermediate clutch is closed quickly to start the engine, then the starting process is faster, but heat generation increases

Engineering Contradiction:
Improveclutch switching speedVSAvoidheat loss in clutch
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The system performs preliminary acceleration of the flywheel during electric driving mode, building up kinetic energy before the clutch engagement. This pre-prepared energy state allows the intermediate clutch to close quickly without generating excessive heat, because the energy transfer is more controlled and the speed differential at engagement is optimized.

Inventive Principle:
Principle #10Preliminary action

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 increases available electrical power for starting, reduces abrupt torque changes, and enables smooth engine starting without jerking, optimizing energy use and vehicle performance, especially at low speeds.

Implementation Method 1

Through the torsion damping unit with the flywheel, which is either separate or integrated into the torsion damping unit, the electric motor drives the flywheel in electric motor driving mode, in which kinetic energy is then stored.

Methodology Applied
Scientific EffectKinetic energy storage: Flywheel

Implementation Method 2

The torsion damping unit is formed, for example, by a dual-mass flywheel, a torsion damper or a so-called speed-adaptive absorber.

Methodology Applied
Scientific EffectTorsion damping: Damping

Implementation Method 3

This kinetic energy and possibly further kinetic energy are then suddenly introduced into the internal combustion engine by closing the intermediate clutch in order to bring it to a sufficiently high speed at which it can run itself.

Methodology Applied
Scientific EffectKinetic energy transfer: Mechanical Force

Data Source

PatentEP3668737B1Hybrid drive transmission unit and method for operating a vehicle with a hybrid drive
Publication Date: 2023.09.06 BAYERISCHE MOTOREN WERKE AG
  • EP3668737B1 patent drawingFigure 1~3
  • EP3668737B1 patent drawingFigure 4~5
  • EP3668737B1 patent drawingFigure 6~8

AI summary

The invention relates to a hybrid drive transmission unit for a vehicle, comprising an internal combustion engine (12) and an electric motor (14) for the drive part, said unit being provided with a power-split transmission (20) with sub-transmissions (22, 24) and a torsion-damping unit with a gyrating mass, interconnected between the internal combustion engine (12) and the power-split transmission (20), and a clutch (38) interconnected between the internal combustion engine (12) and the torsion-damping unit (40), by which means the internal combustion engine (12) can be activated, switching from the electromotive operating mode. The invention also relates to a corresponding method.