Bow Spring Dual-Mass Flywheel Torque Control

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Solution Overview

Problem

The drivetrain of a motor vehicle with a bow spring dual-mass flywheel experiences sudden movements or failures during shifting processes, causing discomfort to vehicle occupants due to the bow spring sticking within the flywheel channel due to centrifugal forces, leading to potential slipping and jerking during acceleration.

Innovation Solution

A method and control unit that generates a torque-transmitting engagement on the dual-mass flywheel to assist static friction, preventing the bow spring from moving and maintaining its position, thereby avoiding slipping and jerking by ensuring it remains on the traction side after shifting, using engine control to apply torque independently of driver input, and synchronizing with engine and transmission speed adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bow spring rotates at high speed in the dual-mass flywheel, then the dual-mass flywheel can effectively uncouple nonuniformity of rotation between the engine and transmission, but the bow spring sticks within the bow spring channel due to centrifugal forces causing failures during shifting

Engineering Contradiction:

Improvedrivetrain reliabilityVSAvoidbow spring sticking

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The control device generates a torque-transmitting engagement before the shifting process completes, ensuring the bow spring is already in the correct position and the static friction is overcome, preventing sticking during the actual shift

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device changes the torque parameter dynamically during shifting by generating a torque-transmitting engagement that exceeds the static friction threshold, allowing the bow spring to move freely between positions without sticking

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the clutch is manually opened and closed for shifting, then gear changes can be made, but sudden movements or failures occur during the shifting process causing occupant discomfort

Engineering Contradiction:

Improvegear shifting capabilityVSAvoidsudden movements during shifting

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The control device detects clutch state and transmission ratio changes, then responds by generating a torque-transmitting engagement to maintain smooth operation during the shifting process

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control device initiates torque-transmitting engagement before the shifting process completes, preparing the drivetrain to absorb the transition smoothly and prevent sudden movements

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the bow spring is held in position by static friction from centrifugal force, then the dual-mass flywheel can maintain stable operation, but the bow spring cannot move to different positions when needed during shifting

Engineering Contradiction:

Improvebow spring position stabilityVSAvoidbow spring position flexibility

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The control device dynamically adjusts the torque parameter during operation, generating a torque-transmitting engagement when position change is needed and allowing static friction to maintain stability during normal operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control device changes the torque parameter to exceed the static friction threshold during shifting, enabling the bow spring to move between positions while maintaining stability during steady-state operation

Inventive Principle:

Principle #35Parameter changes

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 prevents bow spring slipping and associated jerking during shifting and acceleration, enhancing drivetrain smoothness and occupant comfort by maintaining the bow spring's position through controlled torque engagement, reducing the likelihood of drivetrain failures.

Implementation Method 1

the bow spring rotates together with the dual-mass flywheel and is pushed against an inner wall of the bow spring channel on account of centrifugal forces

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the static friction of the bow spring in the bow spring channel, which static friction is caused by centrifugal force

Methodology Applied

Scientific EffectStatic friction: Static Friction

Data Source

PatentUS10844915B2Method and control unit for avoiding failure in the drivetrain of a vehicle

Publication Date: 2020.11.24 BAYERISCHE MOTOREN WERKE AG

AI summary

A method for controlling a drivetrain of a vehicle during a shift process is described. The drivetrain includes a drive engine which is connected via a bow spring dual-mass flywheel to a transmission which can be uncoupled by way of a clutch. The bow spring dual-mass flywheel includes a bow spring which is arranged in a bow spring channel. The method includes detecting that the clutch is closed within the scope of a shift process. Furthermore, the method includes generating a torque intervention at the bow spring dual-mass flywheel independently of a torque request by a driver of the vehicle, in such a way that the bow spring is arranged on the same side of the bow spring dual-mass flywheel after the closing of the clutch as before the opening of the clutch.