Segmented Pinion Gear for Engine Starter Synchronization

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Solution Overview

Problem

Existing engine starter systems face challenges in achieving reliable synchronization and phase matching between the pinion gear and ring gear during engine restart, particularly when the ring gear is rotating, leading to noise, wear, and delays due to complex configurations, RPM differences, and friction issues.

Innovation Solution

The engine starter system incorporates a pinion unit with a first pinion gear for synchronization and a second pinion gear for rotation force transmission, allowing for stable meshing even with RPM differences, using a push-out mechanism and specific tooth shapes to ensure precise alignment and reduce friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex synchronization mechanism is used to achieve precise RPM matching between pinion gear and ring gear, then meshing reliability is improved, but device complexity and size increase

Engineering Contradiction:

Improvemeshing reliabilityVSAvoidsynchronization mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pinion gear is divided into two distinct segments: a first pinion gear for synchronization that engages with the ring gear during idle stop restart, and a second pinion gear for normal operation. This segmentation allows each segment to be optimized for its specific function, simplifying the overall synchronization mechanism while maintaining reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A synchronization friction surface is introduced as an intermediary element between the first pinion gear and the ring gear. This friction surface enables passive speed synchronization through friction contact during meshing, eliminating the need for complex active control mechanisms while ensuring reliable engagement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If passive speed synchronization by friction is used to simplify the mechanism, then device complexity is reduced, but complete synchronization with phase matching cannot be achieved

Engineering Contradiction:

Improvesynchronization mechanism complexityVSAvoidphase matching accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the pinion gear system are given different properties: the first pinion gear has a synchronization friction surface for passive speed matching, while the second pinion gear has standard gear teeth for torque transmission. This local differentiation enables both simplified synchronization and reliable phase-matched engagement

Inventive Principle:

Principle #3Local quality

3Productivity

If the pinion gear is brought into contact with the ring gear after synchronization by slip, then meshing is achieved, but noise and wear increase due to phase mismatch

Engineering Contradiction:

Improvemeshing speedVSAvoidnoise and wear

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The synchronization friction surface performs preliminary speed matching between the first pinion gear and the ring gear before final meshing engagement. This preliminary action ensures that when the gears come into full contact, their speeds are already synchronized, preventing impact, noise, and wear that would occur from mismatched speeds

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The friction between the synchronization surface and the ring gear, which could be considered a harmful factor causing slip, is converted into a beneficial mechanism for passive speed synchronization. This friction enables the first pinion gear to automatically match the ring gear's speed during idle stop restart without complex control systems

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enables reliable synchronization and phase matching at contact, minimizing noise, wear, and delay, while maintaining a compact design and reducing the risk of bouncing and transmission loss.

Implementation Method 1

a first pinion gear having a tooth shape for synchronization, for first colliding with the ring gear upon start of meshing with the ring gear

Methodology Applied

Scientific EffectCollision: Impact Force

Implementation Method 2

synchronization up to a predetermined difference in RPM by friction of a portion of the mechanism

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP2650529B1engine

Publication Date: 2020.03.11 MITSUBISHI ELECTRIC CORP

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AI summary

Provided is an engine starter which carries out, even when a pinion gear is meshed while a ring gear is rotating, more reliable synchronization and phase matching at the moment of a contact. The engine starter includes: a starter motor; a pinion unit (30) for sliding in an axial direction on an output shaft of the starter motor; and a ring gear (100) which meshes with a pinion pushed out by a push-out mechanism (60) and receives a transmission of a rotational force of the starter motor to thereby start an engine, and the pinion portion (30) includes a pinion gear divided in the axial direction into two pinion gears which are a first pinion gear (35) having a protruded shape for synchronization, for first colliding with the ring gear upon start of meshing with the ring gear, and a second pinion gear (34) for serving to transmit the rotational force after the meshing.