Adjustable output constant current source for auxiliary power unit oil level measurement

By designing an adjustable output constant current source and switching between different current networks, the aging problem of the PT100 sensor under high current was solved, improving measurement accuracy and lifespan, and ensuring the accuracy of lubricating oil level measurement.

CN224383628UActive Publication Date: 2026-06-19KEDING TECHNOLOGY (WUXI) CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
KEDING TECHNOLOGY (WUXI) CO LTD
Filing Date
2025-09-17
Publication Date
2026-06-19

AI Technical Summary

Technical Problem

In the existing technology, the PT100 temperature sensor of the auxiliary power unit of aero-engine operates under high current for a long time, which leads to a decrease in measurement accuracy and sensor aging, affecting measurement accuracy and lifespan.

Method used

An adjustable output constant current source was designed. By switching between a first current network and a second current network, a constant current source of 1mA, 5mA, 50mA or 70mA was provided. Combined with an operational amplifier unit and a drive unit, the PT100 sensor was protected to avoid long-term high-current operation.

Benefits of technology

It effectively protects the PT100 sensor, slows down the aging process, improves measurement accuracy and lifespan, and ensures the accuracy of lubricating oil level measurement.

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Abstract

This application provides an adjustable output constant current source for measuring the lubricating oil level of an auxiliary power unit, belonging to the field of lubricating oil level measurement technology. Based on the voltage provided by a reference source, a second chip switches between the first and second networks. Further adjustments are made through an amplifier circuit and a drive power supply, allowing the measuring PT100 to operate at a high measuring current for a short period when measuring the lubricating oil level in an aero-engine auxiliary power unit. Both current networks are adjustable. This avoids the measuring resistor PT100 from operating at high current for extended periods, preventing resistance drift and thus slowing down equipment aging and protecting the stability of the measuring resistor.
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