Hall Sensor Piston Position Sensing for Compression Ratio Measurement

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Solution Overview

Problem

Existing measuring devices for internal combustion engines face challenges in directly and precisely measuring the compression ratio without interfering with the engine's operation or modifying its geometry, particularly in the restricted space defined by the cylinder block.

Innovation Solution

A measuring device comprising a target passage detector, a Hall effect sensor, and a hinged configuration that allows precise placement within the cylinder block without damaging the internal surfaces, using a target on the piston's skirt or connecting rod to detect the piston's position at bottom dead center, facilitating accurate compression ratio measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a target passage detector is integrated into the cylinder block to measure piston position, then measurement precision is improved, but the device complexity and risk of damaging cylinder internal surfaces increase

Engineering Contradiction:

Improvepiston position measurementVSAvoidmeasuring device structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The measuring device is divided into two separate parts: a target passage detector carried by the piston and a sensor fixed on the cylinder block. This segmentation allows each component to be optimized independently - the detector moves with the piston while the sensor remains stationary, reducing overall system complexity while maintaining measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A magnetic target is introduced as an intermediary element that couples the moving piston to the stationary sensor. The target carries magnetic elements that interact with the Hall effect sensor without requiring direct mechanical contact or complex integration into the cylinder block, thereby simplifying the measuring device structure while enabling precise position detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If additional measuring elements are placed in the cylinder block space, then measurement capability is improved, but the harmful factors affecting engine operation increase

Engineering Contradiction:

Improvecompression ratio measurementVSAvoidinterference with engine operation

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The target passage detector is extracted from the cylinder block and transferred to the piston itself. This removes the measuring element from the restricted cylinder block space, eliminating interference with engine operation while maintaining the ability to measure piston position and compression ratio through the magnetic target-sensor interaction.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical integration of a sensor into the cylinder block is replaced with a magnetic field-based detection system. The Hall effect sensor detects the position of magnetic elements on the piston target wirelessly through the cylinder block material, eliminating the need for physical integration that would interfere with engine operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a fixed sensor arrangement is used in the cylinder block, then device complexity is reduced, but measurement precision deteriorates due to space constraints

Engineering Contradiction:

Improvesensor arrangementVSAvoidpiston position detection

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The measuring device transitions from a static sensor arrangement to a dynamic system where the target passage detector moves with the piston. This dynamic configuration allows the detector to maintain optimal positioning relative to the combustion chamber throughout the piston stroke, improving measurement precision while keeping the overall device complexity low through the simplicity of the magnetic target-sensor interaction.

Inventive Principle:

Principle #15Dynamics

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

Enables direct and precise measurement of the piston's position and compression ratio without altering the engine's geometry, ensuring reliable operation and easy installation/maintenance, while avoiding interference with the engine's moving parts.

Implementation Method 1

The passage detector is a Hall effect sensor

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3631375B1Motor comprising a measuring device for an internal combustion engine comprising a target passing detector

Publication Date: 2021.03.24 MCE 5 DEV

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AI summary

The invention relates to an internal combustion engine comprising a connecting rod and a target arranged on one of the lateral reinforcing walls of the piston or on the small end of the connecting rod, a crankcase defining at least one cylinder and having at least one bore opening out under the cylinder. The engine comprises a measuring device (9) arranged in the bore of the crankcase and having a target passage detector (10), a connector (11) and at least one cable connecting the passage detector (10) to the connector (11). The target is arranged opposite the passage detector (10), when the piston is near a bottom dead centre position.