Single-Coil Starter Switch with Drive Spring for Low Current Control

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Solution Overview

Problem

Conventional starters with dual-coil electromagnetic switches require high operating currents, complex circuitry, and increased costs due to the need for multiple parts and processes, making them inefficient and costly.

Innovation Solution

A starter system utilizing a single-coil electromagnetic switch with a separate starting circuit, where the switch coil is electrically separated from the motor circuit, reducing the number of parts and simplifying the circuit composition, and employing a drive spring to manage the pinion gear's movement, allowing for a smaller pinion gear mass and lower operation currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a dual-coil electromagnetic switch is used to increase magnetic force for moving the pinion gear and clutch, then the attracting force is improved, but the operating current increases to about 40 amperes which cannot be controlled directly by a switch with ECU

Engineering Contradiction:

Improveattracting forceVSAvoidoperating current

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The patent segments the load by separating the pinion gear from the clutch, so only the pinion gear is moved by the electromagnetic switch. This reduces the moving mass and allows for a single-coil design with lower operating current that can be directly controlled by the ECU.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the dual-coil electromagnetic switch with a single-coil electromagnetic switch combined with a drive spring mechanism. The spring provides additional mechanical force to move the pinion gear, allowing the electromagnetic coil to operate at lower current levels while achieving the same effect.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Force

If a dual-coil electromagnetic switch with attracting coil and holding coil is used, then the magnetic force is increased, but the number of parts and manufacturing processes increases

Engineering Contradiction:

Improvemagnetic forceVSAvoidnumber of parts

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent merges the functions of the attracting coil and holding coil into a single coil. The single coil performs both attraction and holding functions, eliminating the need for separate coils and reducing the number of parts and manufacturing processes.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a drive spring as an intermediary mechanical element that works together with the single electromagnetic coil to achieve the desired pinion gear movement. The spring provides additional force and stores energy, allowing the coil to be simpler while still achieving the required effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the pinion gear and clutch move together as a unit, then the structure is simplified, but the mass of the movable body increases requiring higher magnetic force

Engineering Contradiction:

ImprovestructureVSAvoidmass of movable body

Core Design Contradiction:

Device complexityVSWeight of moving object

Solution Approach 1:

The patent segments the movable components by separating the pinion gear from the clutch. Only the pinion gear is attached to and moved by the electromagnetic switch's shift lever, while the clutch remains separate. This significantly reduces the moving mass that the electromagnetic switch must move.

Inventive Principle:

Principle #1Segmentation

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 reduces the number of parts and manufacturing processes, lowers costs, and simplifies the circuitry, enabling direct control of the electromagnetic switch by the ECU without the need for a starter relay, while maintaining efficient engine starting performance.

Implementation Method 1

a plunger having the switch coil therein that moves in response to magnetism that the switch coil generates

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

employing a drive spring to manage the pinion gear's movement

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8169281B2Starter for engines and its starting circuit

Publication Date: 2012.05.01 DENSO CORP

AI summary

The starter has a system of pushing the pinion gear in the direction of the anti-motor side by using the attracting power of the electromagnetic switch via the shift lever. The switch coil of the electromagnetic switch is constituted of one coil that is electrically separated from the motor circuit. The mass of pinion gear is set to 100 g or less, the switch extrusion power stored in the drive spring is set to 70 N (Newton) or less, and the operation current of the electromagnetic switch is set to 12 amperes or less. With this starter, since the switch coil and the motor circuit can be electrically separated, the terminal for connection for connecting the conventional attracting coil and conventional “M terminal bolt” can be abolished. Further, by setting the operation current of the electromagnetic switch 10 to 12 amperes or less, it is possible to control the operation current directly by the ECU.