Wear Debris In Lubricating Oil Research Articles

The Optimization of Parallel Resonance Circuit for Wear Debris Detection by Adjusting Capacitance

Wear debris in lubrication oil provides important information for marine engine condition monitoring and faults diagnosis. Inductive sensors have been widely used to detect wear debris in lubrication oil. To improve the sensitivity, the inductive coil is always connected with a capacitor in parallel to form parallel LC resonance-sensing circuit. A previous study optimized the parallel resonance circuit by adjusting the excitation frequency. However, multiple parameters (namely, excitation signal, signal detection circuits, and signal-processing program, etc.) need to be adjusted accordingly for a series of the testing frequencies. To simplify the optimization, we propose a method based on adjusting the parallel capacitance in this work. The impedance (inductance and internal resistance) of the sensing coil and its variation induced by particles are first measured, which are the necessary parameters for establishing the function relationship between the parallel capacitance and the relative impedance variation. With the function relationship, the relative impedance variation is calculated directly, and the optimal capacitance is located at the highest absolute value of it. The experimental results for the ferrous and nonferrous particles match the calculation results well. Interestingly, the optimal capacitance for the nonferrous particle was larger than that of the ferrous particle. We speculate that the difference is generated due to the increased resistance induced by the eddy current effect.

Improving Sensitivity of a Micro Inductive Sensor for Wear Debris Detection with Magnetic Powder Surrounded.

The inductive detection of wear debris in lubrication oil is an effective method to monitor the machine status. As the wear debris is usually micro scale, a micro inductive sensor is always used to detect them in research papers or high-tech products. However, the improvement of detection sensitivity for micro inductive sensors is still a great challenge, especially for early wear debris of 20 μm or smaller diameter. This paper proposes a novel method to improve the detection sensitivity of a micro inductive sensor. Regarding the magnetic powder surrounding the sensor, the magnetic field in the core of the sensor where the wear debris pass through would be enhanced due to the increased relative permeability. Thus, the inductive signal would be improved and the detection sensitivity would be increased. It is found that the inductive signal would linearly increase with increasing the concentration of the magnetic powder and this enhancement would also be effective for wear debris of different sizes. In addition, the detection limit of the micro inductive sensor used in our experiment could be extended to 11 μm wear debris by the proposed method.

A high sensitivity wear debris sensor using ferrite cores for online oil condition monitoring

Detecting wear debris and measuring the increasing number of wear debris in lubrication oil can indicate abnormal machine wear well ahead of machine failure, and thus are indispensable for online machine health monitoring. A portable wear debris sensor with ferrite cores for online monitoring is presented. The sensor detects wear debris by measuring the inductance change of two planar coils wound around a pair of ferrite cores that make the magnetic flux denser and more uniform in the sensing channel, thereby improving the sensitivity of the sensor. Static testing results showed this wear debris sensor is capable of detecting 11 µm and 50 µm ferrous debris in 1 mm and 7 mm diameter fluidic pipes, respectively; such a high sensitivity has not been achieved before. Furthermore, a synchronized sampling method was also applied to reduce the data size and realize real-time data processing. Dynamic testing results demonstrated that the sensor is capable of detecting wear debris in real time with a high throughput of 750 ml min−1; the measured debris concentration is in good agreement with the actual concentration.

An integrated ultrasonic–inductive pulse sensor for wear debris detection

One approach to detect signs of potential machine failure is to detect wear debris in the lubrication oil of a rotating or reciprocating machine because the size and the concentration of wear debris particles in the oil show a direct relationship with the level of wear. In this article, a proof-of-principle integrated wear debris sensor consisting of an ultrasonic pulse sensor and an inductive pulse sensor for detecting wear debris in lubrication oil is presented. The ultrasonic pulse sensor detects all solid debris (metallic and non-metallic debris). A flow recess structure is utilized to ensure that all wear debris passes the acoustic focal region so that all debris can be accurately counted and sized. The inductive pulse sensor detects and counts all metallic debris (ferrous and non-ferrous) based on the inductive Coulter counting principle. By comparing the results from the two sensing components, the sensor is capable of differentiating and detecting non-metallic debris, ferrous metallic debris and non-ferrous metallic debris.

A high throughput inductive pulse sensor for online oil debris monitoring

A high throughput inductive pulse sensor based on inductive Coulter counting principle for detecting metallic wear debris in lubrication oil is presented. The device detects the passage of metallic debris by monitoring the inductance change of a two-layer planar coil with a meso-scale fluidic pipe crossing its center, which is designed to attain high throughput without sacrificing the sensitivity. The testing results using iron and copper particles ranging in size from 50 to 150 μm have demonstrated that the device is capable of detecting and distinguishing ferrous and non-ferrous metallic debris in lubrication oil with a high throughput.

Real-time monitoring of wear debris in lubrication oil using a microfluidic inductive Coulter counting device

A microfluidic device based on an inductive Coulter counting principle to detect metal wear particles in lubrication oil is presented. The device detects the passage of ferrous and nonferrous particles by monitoring the inductance change of an embedded coil. The device was tested using iron and copper particles ranging in size from 50 to 125 μm. The testing results have demonstrated that the device is capable of detecting and distinguishing ferrous and nonferrous metal particles in lubrication oil; such particles can be indicative of potential machine faults in rotating and reciprocating machinery.