Fuel Injector Force Sensor Strain Gauge Integration
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Solution Overview
Problem
Existing fuel injectors face complex and costly manufacturing processes due to the need for precise contact surfaces for pressure sensors, which are difficult to access and require multi-part housing constructions.
Innovation Solution
A fuel injector design featuring a force sensor with a strain gauge element connected to a disk-shaped sealing membrane, eliminating the need for a contact surface and using a single-part housing, with the strain gauge positioned at an axial distance from the sealing element to prevent contact during deformation, and a welded connection between the carrier and sealing elements for secure sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor with a contact surface at the base of the recess is used, then the sensor can be positioned in the recess, but the manufacturing complexity and cost increase due to the need for precise, difficult-to-access contact surfaces
Solution Approach 1:
The patent replaces the traditional pressure sensor that requires a mechanical contact surface with a strain gauge element that measures strain directly on the sealing membrane. This substitution eliminates the need for a precisely machined contact surface at the base of the recess, as the strain gauge measures deformation of the membrane itself, thereby resolving the contradiction between measurement precision and manufacturing complexity
Solution Approach 2:
The patent uses the sealing membrane as a dual-functional element: it serves both as a seal and as the measurement element for the strain gauge. The strain gauge is arranged on the side of the sealing membrane facing away from the recess, allowing it to measure membrane deformation without requiring a contact surface at the recess base, thus simplifying manufacturing while maintaining measurement accuracy
2Ease of manufacture
If a multi-part housing construction is used to form the receiving space, then the contact surface can be accessed for manufacturing, but the device complexity increases
Solution Approach 1:
The patent merges the sealing function and the measurement function into a single integrated structure. The strain gauge is mounted on the sealing membrane itself, eliminating the need for a separate receiving space with a contact surface. This consolidation reduces device complexity by removing unnecessary structural elements while maintaining manufacturability
Solution Approach 2:
The patent extracts the measurement function from the housing structure and relocates it to the sealing membrane. By placing the strain gauge on the membrane rather than requiring a contact surface in the housing, the design eliminates the need for complex multi-part housing constructions, thereby reducing device complexity while preserving manufacturing ease
3Volume of moving object
If the strain gauge element is positioned close to the sealing element, then the structure is compact, but the strain gauge may contact the bottom of the recess during deformation
Solution Approach 1:
The patent positions the strain gauge element on the side of the sealing membrane facing away from the recess, utilizing the third dimension (axial direction) to resolve the conflict. This spatial arrangement ensures that during membrane deformation, the strain gauge does not contact the recess bottom, maintaining measurement reliability without requiring excessive space
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 design simplifies manufacturing, ensures accurate force measurement, and provides a reliable, cost-effective solution with reduced component tolerances and easier assembly, while maintaining the integrity of the sealing and measurement processes.
Implementation Method 1
the sensor element is designed in the form of a force sensor with at least one strain gauge element
Implementation Method 2
a welded connection between the carrier and sealing elements for secure sealing
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a fuel injector (10), in particular a common-rail injector for self-igniting internal combustion engines, comprising an injector housing (11) in which a sensor element is arranged in a low-pressure region (45) for at least indirectly detecting a fuel pressure prevailing in a high-pressure region (20), the sensor element resting against an elastically deformable sealing element (69) on the side remote from the high-pressure region (20), said sealing element sealing a receiving space (66) for the sensor element. According to the invention, the sensor element is designed in the form of a force sensor (75) having at least one strain measuring element, the force sensor (75) being connected to the sealing element (69).