Engine Restart Positioning Using Stall-Detected Reverse Rotation

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Solution Overview

Problem

Existing methods for starting single-cylinder internal combustion engines using an electric motor face challenges in determining fixed angles or times for inverse rotation due to the spacing of adjacent compression phases, often requiring additional sensors, which complicates the re-starting process.

Innovation Solution

A starting process involving a positioning step with forward and inverse rotations determined by stall detection and maximum rotation angles, without the need for additional sensors, ensuring precise piston positioning for successful engine re-start.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed inverse rotation angle or time is used for re-starting, then the procedure is simple to implement, but it cannot guarantee successful starting in single-cylinder engines due to the 2π spacing of compression phases

Engineering Contradiction:

Improvesimplicity of re-starting procedureVSAvoidsuccess rate of engine re-start

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system uses feedback from current monitoring during inverse rotation to detect piston stall conditions. When the piston stalls during inverse rotation, it indicates the compression phase has been reached, providing real-time feedback to adjust the rotation control accordingly.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs a preliminary forward rotation before inverse rotation to position the piston away from the compression phase. This preliminary action ensures that the subsequent inverse rotation will successfully reach the compression phase without risking a stall condition.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If additional sensors are added to detect compression phase position, then starting reliability improves, but device complexity increases

Engineering Contradiction:

Improveaccuracy of compression phase detectionVSAvoidnumber of sensors and components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses the existing electric motor's current consumption characteristics to self-diagnose the piston position. The motor controller monitors current variations during rotation, and the piston's mechanical resistance during compression phase creates detectable current peaks, allowing the system to determine position without external sensors.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical position detection sensors with an electrical sensing method. By monitoring the electrical current drawn by the motor during rotation, the system indirectly detects mechanical conditions (piston position and compression phase) through electrical parameters, eliminating the need for separate mechanical sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Power

If the electric motor is sized for maximum torque, then starting capability is ensured, but motor size and cost increase

Engineering Contradiction:

Improvestarting torque capabilityVSAvoidelectric motor size

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The system uses dynamic control strategies including variable rotation speed and torque adjustment during the starting sequence. By optimizing the rotation profile (acceleration rates, hold positions, and transition timing), the system maximizes the utilization of available torque, allowing a smaller motor to achieve the same starting capability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The starting process uses periodic forward and inverse rotations to progressively advance the piston toward the compression phase. This periodic action allows the motor to build up kinetic energy and momentum, reducing the peak torque requirements compared to a single direct starting attempt.

Inventive Principle:

Principle #19Periodic 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

Ensures reliable engine starting with optimized torque and size utilization of the electric motor, guaranteeing successful re-starts by accurately positioning the piston relative to compression phases.

Implementation Method 1

providing the use of an electric motor (12) acting on the driveshaft (13) of the internal combustion engine (1)

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

the piston, inside the cylinder, in the position requesting the lowest possible torque for re-starting, by considering that the latter has to take place during a very short instant

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentEP3175109B1Process for starting an internal combustion engine

Publication Date: 2026.01.07 PIAGGIO & C SPA

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AI summary

A process for starting an internal combustion engine, providing the use of an electric motor acting on the driveshaft of the internal combustion engine, provides a positioning step, activated upon switching-off the engine, and a switching-on step, activated after a starting control, wherein said positioning step comprises: a forward rotation by a predetermined forward rotation angle; a detection of a possible stall state followed, in negative case, by an additional forward rotation until reaching a predetermined maximum forward rotation angle; an inverse rotation by a predetermined angle; and a detection of a possible stall state followed, in negative case, by an additional inverse rotation until reaching a predetermined maximum inverse rotation angle