Variable Rate Dampening in Starter Motors

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Solution Overview

Problem

Starter motors for diesel engines with dual mass flywheels experience premature failure due to inability to effectively dampen both low frequency high impact and high frequency low impact loads, as existing dampening members can only address one type of load.

Innovation Solution

A starter motor design incorporating variable rate dampening members that provide different spring rates for high frequency low amplitude oscillations and high amplitude short-duration impacts, using a combination of coil springs and rubber cushions or clip springs positioned around a stationary gear to absorb oscillations and impacts in both rotational directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single rate dampening member is used, then the structure is simple, but it cannot effectively dampen both low frequency high impact and high frequency low impact loads

Engineering Contradiction:

Improvedampening capability for different load typesVSAvoiddampening member structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The dampening member is segmented into multiple spring elements with different spring rates (first spring rate and second spring rate). Each spring element is designed to handle specific frequency ranges, allowing the system to dampen both low frequency high impact loads and high frequency low impact loads simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dampening member transitions from a static single-rate spring to a dynamic multi-rate spring system that automatically adjusts its effective spring rate based on the frequency and amplitude of the applied loads. This dynamic adaptation enables effective dampening across varying operating conditions without requiring complex active control mechanisms.

Inventive Principle:

Principle #15Dynamics

2Reliability

If a multi-rate dampening member is used, then dampening for both load types is achieved, but the manufacturing complexity increases

Engineering Contradiction:

Improvestarter motor lifespanVSAvoiddampening member fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The dampening member utilizes composite spring structures combining materials or designs with different spring rates in a single integrated component. This approach achieves the reliability benefits of multi-rate dampening while streamlining the manufacturing process compared to assembling multiple separate springs.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different portions of the dampening member are designed with locally optimized properties - some sections have higher spring rates for high frequency dampening while other sections have lower spring rates for low frequency impact absorption. This local differentiation allows the entire component to handle multiple load types effectively.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If dampening members are positioned only on one side of the stationary gear, then the structure is simpler, but dampening in both rotational directions is not provided

Engineering Contradiction:

Improvedampening coverage for rotational directionsVSAvoidnumber of dampening members

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The dampening member configuration utilizes asymmetric positioning combined with the inherent bidirectional dampening capability of the spring structure. This allows effective dampening in both rotational directions while maintaining a relatively simple overall structure that does not require complete symmetry in component placement.

Inventive Principle:

Principle #4Asymmetry

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 starter motor effectively prolongs its lifespan by absorbing a broad range of oscillations and impacts, preventing premature failure and allowing for customization of spring rates to match engine natural frequencies, thus ensuring smooth operation under varying conditions.

Implementation Method 1

variable rate dampening members provide variable rate dampening such that when the starter motor experiences high frequency, low amplitude oscillations the dampening members provide a first spring rate, and when the starter motor experiences a high amplitude impact for a short duration of time, the dampening members provide a second spring rate that is stronger than the first spring rate

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS7360464B2Variable rate impact and oscillation absorber in starter motors

Publication Date: 2008.04.22 FORD GLOBAL TECH LLC

AI summary

A starter motor is provided having a starter motor housing with an electric motor mounted therein. A stationary gear base mounted onto the starter motor housing and includes a plurality of pockets formed therein and spaced thereabout. A stationary gear is rotatably mounted within the stationary gear base for limited rotational movement and includes a plurality of legs that extend into the pockets. One or more variable rate dampening members are positioned within the pockets, circumferentially between the legs of the stationary gear and inner walls of the pockets. The variable rate dampening members provide variable rate dampening such that when the starter motor experiences high frequency, low amplitude oscillations the dampening members provide a first spring rate and when the starter motor experiences a high amplitude impact for a short duration of time, the dampening members provide a second spring rate that is stronger than the first spring rate.