Piezoelectric Sensor Cage for Fuel Injector Signal Stability
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Solution Overview
Problem
Existing sensor arrangements for force or pressure measurement in fuel injectors face challenges such as complex production processes, potential thermal damage, signal loss, and mechanical degradation due to adhesive or soldering connections, which affect the stability and longevity of the sensor elements.
Innovation Solution
A sensor arrangement where sensor elements are not glued or soldered to end faces, instead being clamped within a non-conductive plastic cage that provides mechanical stability and insulation, allowing for simplified assembly and reduced production costs, with an electrode connected to a busbar for signal transmission, and a force distribution plate for uniform pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor elements are connected via adhesive bond or soldering, then electrical connection is achieved, but thermal damage and mechanical degradation occur
Solution Approach 1:
The patent introduces a cage made of thermally insulating material as an intermediary between the sensor element and the heating element. This cage mediator prevents direct thermal contact while maintaining electrical connection through the electrode, thereby protecting the piezoelectric material from thermal damage during soldering or heating processes.
Solution Approach 2:
The patent segments the connection system into distinct functional components: the cage provides mechanical support and thermal insulation, the electrode provides electrical connection, and the sensor element performs sensing. This segmentation allows each component to optimize its specific function without interfering with others, particularly protecting the sensor from thermal effects.
2Ease of manufacture
If adhesive bonding is used to connect sensor elements, then assembly is achieved, but signal loss and mechanical degradation occur
Solution Approach 1:
The cage acts as a mediator that provides mechanical support and positioning without requiring adhesive bonding. The sensor element is held in place by the cage structure and electrical contact with the electrode, eliminating the need for adhesives that could cause signal loss or mechanical degradation.
Solution Approach 2:
The patent replaces the adhesive bonding mechanism with a mechanical clamping system using the cage. This mechanical support system avoids the chemical and mechanical issues associated with adhesives while maintaining assembly simplicity through the snap-fit or clamp design of the cage.
3Strength
If sensor elements are clamped tightly to ensure mechanical stability, then structural integrity is improved, but signal loss occurs due to unfavorable clamping
Solution Approach 1:
The cage applies localized mechanical support at specific points (clamping zones) rather than uniform tight clamping across the entire sensor element. This local quality approach provides sufficient mechanical stability at critical locations while leaving the piezoelectric material free from excessive stress that would cause signal loss.
Solution Approach 2:
The cage serves as a mediator that distributes mechanical support forces through its structure rather than applying direct point loads to the sensor element. This intermediary structure provides mechanical stability while minimizing stress concentration that would degrade signal quality.
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 configuration simplifies production, enhances mechanical stability, reduces signal loss, and maintains long-term signal integrity by avoiding thermal damage and mechanical degradation, while allowing for precise needle closing time detection in fuel injectors.
Implementation Method 1
at least one sensor element made of a piezoelectric material with two parallel end faces
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The invention relates to a sensor arrangement for force or pressure measurement for installation in a component, in particular a fuel injector for needle closing time detection, comprising, for example, two sensor elements 1a, 1b made of a piezoelectric material with two parallel end faces, each of which forms or receives an electrode, and wherein the sensor elements 1a, 1b are arranged stacked relative to one another. According to the invention, a sensor arrangement is provided whose manufacture is simplified without negatively impacting the function of the sensor arrangement. This is achieved by surrounding the sensor elements 1, 1a, 1b, at least partially, in the region of their side faces, with a cage 3, 3a, 3b, 3c, 3d, 3e, and by clamping the mutually facing end faces of the sensor elements 3, 3a, 3b, 3c, 3d, 3e directly or indirectly in contact.