Piston-Integrated Target Layout for Compression Ratio Sensing
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Solution Overview
Problem
Existing internal combustion engine piston designs face challenges in accurately measuring compression ratio without interfering with the engine's geometry or operation, particularly when integrating a target and sensor system within the restricted space of the cylinder block.
Innovation Solution
A piston design where the target is carried by a holding body located inside the piston, with a flexible arm clipped to the skirt, allowing precise positioning without modifying the cylinder geometry, and a Hall effect sensor detector placed outside the skirt's sweep zone for direct measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a target and sensor system are integrated within the cylinder block to measure compression ratio, then measurement precision is improved, but the device complexity increases and the available space is reduced
Solution Approach 1:
The target is nested within the piston's internal space, specifically positioned in the cavity formed by the skirt and piston body. This allows the measurement component to be housed within the existing piston structure without adding external complexity to the cylinder block assembly.
Solution Approach 2:
The target is positioned in the vertical dimension within the piston cavity, allowing the sensor to detect its position as the piston moves vertically in the cylinder. This utilizes the existing vertical motion dimension of the piston without requiring additional spatial dimensions.
2Measurement precision
If additional components are placed within the cylinder block volume, then measurement capability is improved, but the ease of manufacture deteriorates due to precise positioning requirements
Solution Approach 1:
The target is merged with the piston structure, being carried by the piston body and positioned within its internal cavity. This integration ensures that the target moves with the piston as a single unit, eliminating the need for separate positioning mechanisms and reducing manufacturing complexity.
Solution Approach 2:
The piston's own internal cavity serves as the housing for the target, eliminating the need for additional external mounting structures. The piston structure itself provides the positioning and support for the measurement component.
3Measurement precision
If a target is fixed to the piston to enable non-contact sensing, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The target is nested within the piston's internal cavity, utilizing the existing space rather than adding external components. This reduces the overall device complexity while maintaining the measurement functionality.
Solution Approach 2:
The target serves as a simple geometric marker that copies the piston's position without requiring complex mechanisms. Its simple shape and positioning allow for straightforward detection by the sensor.
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 precise and direct measurement of piston position without damaging the cylinder or affecting engine operation, facilitating the adjustment of compression ratio and improving energy efficiency.
Implementation Method 1
The sensor is fixed to the cylinder block and detects the proximity of a target fixed to the piston or connecting rod. This target can be a Hall effect sensor, in which case it comprises a magnetic element or a metallic mass.
Data Source
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Figure 5
AI summary
The invention relates to a piston (1) for an internal combustion engine, comprising a skirt (2) defining an inner space of the piston (1) and having a skirt bottom (6); and a target (10) arranged under the skirt bottom (6) to engage with a passage detector (11) arranged in the engine. The target (10) is supported by a holding body (14) held at least partially inside the inner space of the piston (1). The invention likewise relates to an engine comprising such a piston.