Piezo Fuel Injector Sensor Assembly
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Solution Overview
Problem
Existing fuel injectors with piezoelectric sensors face challenges in production simplicity and functional testing, leading to potential mechanical and electrical issues during assembly and operation.
Innovation Solution
A fuel injector design featuring a piezo element with two electrode layers and insulating layers formed through the sintering process, along with a compact assembly structure and specific housing features, such as a cover-shaped housing made of Invar, ensures easy assembly, robust connections, and effective insulation, allowing for precise geometric accuracy and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric elements are used to detect fuel pressure and nozzle needle position, then measurement precision is improved, but device complexity increases due to multiple electrode layers and insulating layers requiring separate assembly
Solution Approach 1:
The patent combines multiple components (piezoelectric element, electrode layers, and insulating layers) into a single integrated measuring device assembly. This merging eliminates the need for separate assembly of these components, reducing device complexity while maintaining the precise measurement capability provided by the piezoelectric elements
2Ease of manufacture
If piezoelectric elements with multiple layers are assembled separately, then manufacturing flexibility is improved, but ease of manufacture deteriorates due to complex assembly procedures
Solution Approach 1:
The measuring device is designed as an integrated assembly where the piezoelectric element, electrode layers, and insulating layers form a unified structure. This integration simplifies the manufacturing process by eliminating complex multi-step assembly procedures while maintaining the functional benefits of the layered piezoelectric structure
3Reliability
If functional testing is performed after assembly, then production efficiency is improved, but reliability deteriorates due to inability to detect defects early
Solution Approach 1:
The integrated measuring device assembly allows functional testing to be performed on the complete assembly before installation in the fuel injector. This preliminary testing approach enables early detection of defects in the piezoelectric elements and their connections, improving reliability without significantly impacting production efficiency since the assembly is already integrated
4Volume of stationary object
If connection lines are arranged outside the assembly cross section, then ease of connection is improved, but volume increases due to larger radial installation space
Solution Approach 1:
The connection lines are arranged within the cross-section of the measuring device assembly, nesting them inside the existing structure rather than placing them externally. This nesting approach reduces the overall volume of the measuring device while the connection lines remain accessible for electrical connection through the assembly structure
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 simplifies production, enhances insulation, and provides a robust and reliable measuring device capable of accurately detecting fuel pressure, maintaining optimal performance across varying temperatures and operational conditions.
Implementation Method 1
a sensor element designed as a piezoelectric element is glued to the surface of the injector housing... the piezo element glued in the area of the deformation area generates voltage signals depending on the deformation
Implementation Method 2
the piezo element together with the insulating layers as an assembly formed in the sintering process
Implementation Method 3
a deformation area is formed on the injector housing at the mounting location of the piezo element, which bulges all the more elastically outwards, the greater the fuel pressure in the inlet bore
Data Source
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AI summary
The invention relates to a fuel injector (10), in particular a common-rail injector, with an injector housing (11) in which a high-pressure chamber (15) is formed, which can be supplied with pressurized fuel via a supply bore (19) arranged in the injector housing (11), with at least one injection opening (12) formed in the injector housing (11) and connected at least indirectly to the high-pressure chamber (15) for injecting fuel into the combustion chamber of an internal combustion engine, with an injection element (16) that releases or closes the at least one injection opening (12), and with a measuring device (30) for at least indirectly detecting the pressure in the high-pressure chamber (15) or the supply bore (19), wherein the measuring device (30) is configured to detect an elastic deformation of a deformation area (27) arranged in operative connection at least indirectly with the supply bore (19) or the high-pressure chamber (15).and wherein the measuring device (30) comprises a piezoelectric element (41) which is housed in a housing (35) connected to the injector housing (11).