U-Shaped Contact Spring for Pressure Measuring Glow Plug
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Solution Overview
Problem
Contact springs in pressure measuring glow plugs introduce interference signals that degrade measurement accuracy due to non-axial and tilting forces resulting from installation tolerances and vibrations.
Innovation Solution
A U-shaped, bent metal contact spring with a reduced width in its middle section and expanding ends, which reduces tilting resistance and maintains low electrical resistance, is used to connect the glow pin to the center pole, allowing for improved measurement accuracy by orienting the contact spring in a defined radial direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact spring is used to electrically connect the glow pin to the center pole, then electrical connection is achieved, but interference signals are generated that reduce measurement accuracy
Solution Approach 1:
The contact spring has non-uniform width along its length, with the middle section having reduced width compared to the end sections. This local variation in geometry creates different stiffness characteristics in different regions, allowing the spring to better accommodate tilting moments while maintaining electrical contact functionality.
Solution Approach 2:
The width parameter of the contact spring is changed along its length to optimize performance. The middle section has a smaller width to reduce tilting resistance, while the end sections have larger width to ensure stable electrical contact and provide mounting surfaces.
2Measurement precision
If the contact spring width is reduced in the middle section to minimize tilting moment resistance, then measurement accuracy improves, but electrical resistance increases
Solution Approach 1:
The contact spring has non-uniform width along its length, with the middle section having reduced width compared to the end sections. This local variation in geometry creates different stiffness characteristics in different regions, allowing the spring to better accommodate tilting moments while maintaining electrical contact functionality.
Solution Approach 2:
The width parameter of the contact spring is changed along its length to optimize performance. The middle section has a smaller width to reduce tilting resistance, while the end sections have larger width to ensure stable electrical contact and provide mounting surfaces.
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 significantly reduces the impact of contact spring interference on measurement accuracy, ensuring precise pressure readings by minimizing the dependence of the spring constant on radial orientation and preventing heat loss.
Implementation Method 1
The U-shaped, bent metal strip forms a spring having two legs
Implementation Method 2
the electrical resistance of the contact spring is still small enough to prevent any problematic heat loss from arising
Data Source
AI summary
Described is a pressure measuring glow plug with a housing, a glow pin, which projects out of the housing and can be displaced in its longitudinal direction relative to the housing against a restoring force. A sensor acquires the position of the glow pin or a pressure acting on the glow pin, and a center pole is arranged in the housing and electrically connected to the glow pin via a contact spring. This disclosure provides that the contact spring is a U-shaped, bent metal strip, which in a middle section has a reduced width, and broadens from the middle section toward its two ends.