Pressure-Measuring Plug With Ring-Shaped Sensing Structure
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Solution Overview
Problem
Existing pressure-measuring plugs for combustion engines face issues with hysteresis, sealing, and sensitivity to external influences like temperature, and require additional holes in the engine head, leading to increased costs and practical challenges.
Innovation Solution
A pressure-measuring plug with a ring-shaped sensing structure and internal thread for mounting a rod-shaped element, allowing for easy assembly and disassembly, and integration with existing spark plugs without requiring an extra hole in the engine head, featuring a steel body for grounding and a sealing profile for robust sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is integrated into the spark plug, then the pressure measurement function is achieved, but the product lifetime mismatch causes reliability issues and the entire assembly must be replaced when one component fails
Solution Approach 1:
The pressure-measuring plug is divided into separate functional components: a pressure sensor assembly with ring-shaped sensing structure and an inner core, and a rod-shaped element for spark plug functionality. The internal thread allows these segments to be assembled and disassembled independently, enabling replacement of only the failed component rather than the entire integrated assembly.
2Reliability
If an extra hole is drilled in the engine head for pressure sensor placement, then pressure measurement is enabled, but manufacturing costs and practical complexity increase
Solution Approach 1:
The pressure-measuring plug utilizes the existing spark plug hole in the engine head for dual purposes: pressure measurement and spark plug functionality. The rod-shaped element with external thread mounts into the inner core of the pressure sensor assembly, allowing the same opening to serve both functions simultaneously, eliminating the need for an additional hole and reducing manufacturing costs.
3Volume of moving object
If the sensing structure is integrated in the plug body, then the hole dimension is limited, but the rod-shaped element mounting capability is reduced
Solution Approach 1:
The rod-shaped element is nested within the inner core of the ring-shaped sensing structure. The internal thread of the inner core receives the external thread of the rod-shaped element, creating a nested configuration where the spark plug component is housed inside the pressure sensor assembly. This nesting approach maintains compact dimensions while providing versatile mounting capability for different rod-shaped elements.
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
The solution provides a reliable, cost-effective, and long-lasting pressure-measuring plug that is robust to harsh engine conditions, reducing hysteresis and stress, and allowing for separate replacement of spark plug components without affecting the pressure sensor, while maintaining optimal performance.
Implementation Method 1
EP2138819A1 and EP2444786A1 disclose a piezo-resistive pressure-measuring plug for a combustion engine for measuring a pressure. The piezo-resistive pressure-measuring plug comprises a plug body for insertion into a cylinder of the combustion engine, a rod that is arranged in the plug body, a sensing structure comprising a piezo-resistive element.
Data Source
Figure 1~3
Figure 4
AI summary
Disclosed is a pressure-measuring plug (100) for a combustion engine. The pressure-measuring plug comprises a plug body (102) and a ring-shaped sensing structure (104). The plug body comprises an external thread (102A) for mounting the plug body into a cylinder head of the combustion engine. The ring-shaped sensing structure comprises an outer section (104A) and an inner core (104B). A proximal end of the plug body is attached to the outer section. The inner core comprises a through hole (104C) for receiving a rod-shaped element (106). The ring-shaped sensing structure allows the inner core (104B) to move relatively to the outer section (104A) along a cylinder axis (105) of the ring-shaped sensing structure. The inner core (104B) further comprises an internal thread (104B1) for mounting in the through hole (104C) a rod-shaped element (106) with an external thread.