Sensor Element Gap-Free Encapsulation via Injection Molding
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Solution Overview
Problem
Existing sensors face challenges in miniaturization and accurate measurement due to gaps between the casing and sensor elements, which can lead to uneven temperature distribution and incorrect readings.
Innovation Solution
A sensor design where the sensor element is encapsulated by an injection molding compound within a molded part, ensuring a gap-free, moisture-tight connection, with the molded part forming part of the outer contour and the injection molding compound surrounding the sensor element without gaps, using a two-part injection mold to maintain the minimum casing thickness and prevent slipping during the injection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor element is encapsulated by injection molding compound, then measurement precision is improved by eliminating gaps, but device complexity increases due to multi-material construction
Solution Approach 1:
The patent combines the molded part and injection molding compound into a unified casing structure where both materials form integral parts of the enclosure. The molded part provides the base structure while the injection molding compound fills gaps and creates a seamless encapsulation, merging two manufacturing processes into a single integrated component that eliminates measurement errors from gaps.
Solution Approach 2:
The sensor element is nested within the molded part, which is itself nested within the injection molding compound. This multi-layer nesting structure ensures complete encapsulation of the sensor element while maintaining precise thermal contact, as each layer contributes to the overall sealing and structural integrity without creating gaps.
2Reliability
If the sensor element is fully encapsulated by injection molding compound, then reliability is improved by protecting from environmental influences, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
Instead of requiring complete and uniform encapsulation of the entire sensor element, the patent applies partial encapsulation where the injection molding compound covers the critical areas that need protection from moisture and environmental influences. This partial action approach maintains reliability while avoiding the manufacturing difficulties of achieving uniform thickness across all surfaces.
Solution Approach 2:
The casing structure applies different levels of encapsulation to different regions of the sensor element. Critical areas that require moisture protection receive full encapsulation by the injection molding compound, while other areas maintain direct contact with the molded part. This local differentiation optimizes both protection and manufacturability.
3Reliability
If additional coating layers are applied for protection, then reliability improves, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent merges the protective coating function into the structural casing itself. The injection molding compound serves dual purposes: it forms part of the structural enclosure and simultaneously provides the protective coating that shields the sensor element from environmental influences. This consolidation eliminates the need for separate coating steps while maintaining reliability.
Solution Approach 2:
The injection molding compound performs multiple functions simultaneously: structural support, gap filling for thermal contact, moisture barrier, and protective coating. This multi-functionality reduces the overall device complexity by eliminating the need for separate protective layers while maintaining all necessary protection functions.
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 approach allows for reliable, miniaturized sensors with accurate temperature detection by eliminating gaps and ensuring a stable, moisture-tight encapsulation, reducing environmental damage and the need for additional coating layers.
Implementation Method 1
The sensor element is inserted into the molded part and encapsulated by the injection molding compound, so that the molded part is positively connected to the injection molding compound
Implementation Method 2
For example, the electrical resistance of the sensor element can be measured by means of the connection elements, which, in the case of NTC sensors or also PTC sensors, allows a direct conclusion to be drawn about the temperature of the sensor element
Data Source
Figure 1~4
AI summary
The invention relates to a sensing device for detecting a physical quantity, comprising a sensor element (2) which is inserted into a molded part (1), said sensor element (2) having a case formed by a molded part (1) and an injection molding compound (3). The invention further relates to a method for producing a sensing device, comprising the following steps: a) inserting a molded part into an injection mold, b) inserting a sensor element into the molded part, c) injecting the injection molding compound into the injection mold from one direction, said direction being chosen in such a manner that the sensor element (2) is forced against the molded part (1) while the injection molding compound is injected.