Laser Welded Plastic Sensor Housing for Fluid-Tight Sealing
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Solution Overview
Problem
Existing methods for producing electronic sensors with sealed housings face challenges in achieving reliable tightness, especially in wet applications, due to inadequate connections, mechanical stress, and high costs associated with sealing materials and processes like ultrasonic welding.
Innovation Solution
A method involving laser welding of an inner sleeve made from one plastic material with a connection piece made from a second plastic material, having different transmission properties, followed by gluing the housing blank into a housing sleeve, to create a reliable and tight seal without mechanical stress and additional materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If housing parts are connected by gluing, then assembly is simple, but connection strength and tightness are inadequate
Solution Approach 1:
The housing is divided into multiple parts (first housing part, second housing part, third housing part) that are connected through laser welding at specific contact points, allowing localized strong connections rather than relying on overall gluing strength
Solution Approach 2:
The gluing process is replaced with laser welding technology, substituting a chemical bonding method with a thermal joining method that provides superior connection strength and reliability for tight sealing requirements
2Reliability
If seals made of elastic material are used, then tightness is improved, but assembly difficulties and mechanical stress increase
Solution Approach 1:
Elastic sealing rings are replaced with laser-welded joints between housing parts, substituting a mechanical sealing system with a permanent structural connection that eliminates assembly difficulties and mechanical stress on sealing components
Solution Approach 2:
The connection method changes from mechanical (sealing rings under compression) to thermal (laser welding), fundamentally altering how tightness is achieved and eliminating the need for elastic deformation and compression of sealing materials
3Strength
If ultrasonic welding is used, then connection strength is improved, but costs and mechanical stress increase
Solution Approach 1:
Ultrasonic welding is replaced with laser welding, substituting a mechanical vibration-based joining method with an optical-thermal method that eliminates the need for complex sonotrode holders and reduces overall production costs
Solution Approach 2:
The welding mechanism changes from ultrasonic vibration to laser radiation, fundamentally altering the energy input method and eliminating the need for specialized ultrasonic welding equipment and fixtures
4Reliability
If housing is filled with hardening plastic, then tightness is improved, but mechanical stress and adhesion problems occur
Solution Approach 1:
The potting material is completely removed from the housing, extracting the problematic encapsulation step and replacing it with laser welding and gluing methods that achieve tightness without introducing adhesion issues or mechanical stress during curing
Solution Approach 2:
Chemical bonding through potting material adhesion is replaced with thermal joining through laser welding, substituting a method reliant on surface adhesion with one that creates direct structural bonds between housing parts
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 method results in highly reliable, moisture- and dust-resistant sensors with high IP protection, suitable for damp environments, and simplifies the production process with reduced material and cleaning efforts, while maintaining mechanical and electronic component integrity.
Implementation Method 1
connected in a fluid-tight manner to one another by laser welding at at least one contact point
Implementation Method 2
laser radiation used for laser welding
Data Source
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Figure 7
AI summary
The method involves fitting electronic components to be connected with a sensor element in an inner sleeve (30), and mounting the inner sleeve in a housing sleeve, where the inner sleeve is formed from a plastic material. The inner sleeve is connected with a connection piece (40) in a fluid-tight manner at a contact point (43) for producing a housing blank (20) by laser welding. The connection piece is formed from another plastic material, where the two plastic materials have different transmission characteristics. The housing blank is sticked into the housing sleeve.