In this article, an impedance debris sensor capable of simultaneously detecting inductance and resistance parameters is presented, which mainly consists of two planar coils in parallel, two excitation silicon steel strips inserted in the inner hole of coils and a built-in silicon steel strip located in the center of channel. The excitation silicon steel strips and the built-in silicon steel strip establish a detection region with a high-gradient magnetic field to improve the sensitivity of the sensor. And the square channel makes full use of the sensitive detection region, thereby further increasing the detection throughput. Experiments have shown that the amplitudes of the inductance and resistance pulses generated by the same particle many times through the detection region are different. The uncertainty of the sensor can be reduced for accurate size information by combining the detection results of the inductance and resistance parameters. By comparing and analyzing the inductance parameter detection result and the resistance parameter detection result, the impedance debris sensor can distinguish and measure 25  μ m iron particle and 85  μ m copper particle. With its high sensitivity, high throughput, and capability of multiparameter detection, this sensor can potentially be used for health monitoring of hydraulic equipment.

An Impedance Debris Sensor Based on a High-Gradient Magnetic Field for High Sensitivity and High Throughput

A multi-function sensor for online detection of contaminants in hydraulic oil

Inductive oil debris sensors have been widely used in the health monitoring of mechanical equipment. Such sensors are important for fault diagnosis, life prediction, and prevention of catastrophic failures. In this article, the concept that the residual voltage caused by the asymmetry of two incentive coils hinders the improvement of the sensor resolution is theoretically demonstrated for the first time. In order to achieve ultrasensitive detection, a novel two-stage autoasymmetrical compensation circuit (AACC) is introduced into the triple-coil debris sensor to automatically suppress the residual voltage in real time. The experimental results show the successful detection of 70 μ m (diameter or D ) ferrous particles and 165 μ m ( D ) nonferrous particles in a sensing channel with a diameter of 43 mm. The AACC is verified effectively to maintain the residual voltage at an ultrasmall value even in the presence of environmental fluctuations, and the sensitivity of the sensor using AACC is more than 31 times that of the sensor without AACC.

Ultrasensitive Inductive Debris Sensor With a Two-Stage Autoasymmetrical Compensation Circuit

A high throughput and high sensitivity sensor for detection of oil metal debris is presented. The sensor is mainly composed of a planar coil, a ferrite core and a flat channel. The adoption of flat channel can increase the throughput without sacrifice of sensitivity. The comparative experiments show that the ferrite core not only eliminates the phenomenon of multiple pulse peaks for detecting individual metal particle in the flat channel, but also can improve the sensitivity of inductance detection and resistance detection. For detecting 130–140 $\mu \text{m}$ iron particles, the inductance amplitude and SNR (signal-to-noise ratio, the SNR is the amplitude divided by the interference noise) of sensor with ferrite core are 1.17 times and 1.22 times higher than those of sensor without ferrite core, respectively. For detecting 160–170 $\mu \text{m}$ copper particles, the inductance amplitude and SNR of sensor with ferrite core are 1.24 times and 1.28 times higher than those of sensor without ferrite core, respectively, and the resistance amplitude and SNR of sensor with ferrite core are 1.09 times and 1.07 times higher than those of sensor without ferrite core, respectively. In addition, the introduction of resistance detection can increase the ability of sensor to detect non-ferromagnetic metal particles. We can detect iron particles with diameter of $40~\mu \text{m}$ onwards and detect copper particles with diameter of $90~\mu \text{m}$ onwards using the sensor with ferrite core combined with inductance and resistance detection methods. This work improves the throughput of microfluidic high-precision detection, which can provide technical support for large-flow oil detection.

Oil Metal Debris Detection Sensor Using Ferrite Core and Flat Channel for Sensitivity Improvement and High Throughput

A multifunction detection sensor for hydraulic oil contaminants based on a microfluidic chip is proposed, which consists of double solenoid coils and a straight microchannel. The inductance detection model of metal particles and capacitance detection model of nonmetal particles are constructed theoretically. In order to further improve detection sensitivity, experiments of effects of silicon steel sheets on the sensitivity of detection are carried out. Experimental results show that the silicon steel sheets can significantly improve the detection sensitivity of metal particles. The inductance amplitude and signal-to-noise (SNR) of iron particles ranging from 60–130 μm and copper particles ranging from 120–180 μm can be increased by at least 7.0–2.4 and 4.5–2.0 times, respectively. We demonstrate the successful detection of 30 μm iron particles and 90 μm copper particles using double solenoid coils with silicon steel sheets. In capacitance detection experiments, the silicon steel sheets can improve the sensitivity of capacitance detection, but the improvement effect is not obvious. We demonstrate the successful detection of 140 μm water droplets and 240 μm bubbles using double solenoid coils with and without silicon steel sheets. The capacitance amplitude and SNR of detecting water droplets ranging from 140–150 μm and bubbles ranging from 240–250 μm can be increased by 37.4–21.9% and 18.5–8.0% using double solenoid coils with silicon steel sheets, respectively.

https://www.mdpi.com/2072-666X/10/6/377/pdf

Multifunctional Detection Sensor and Sensitivity Improvement of a Double Solenoid Coil Sensor.

A multi-parameter sensor based on microfluidic chip is presented. The sensor consists of a planar coil and a metal wire inserted into the center hole of coil. It can be used as an inductive sensor or capacitive sensor, so multiple parameters can be detected on one sensor. The vertical channel effectively prevents the clogging of the microchannel, reducing the detection error and improving the service life of the detection chip. The related experiments were carried out on the built detection system, which proved the annular microchannel can force that the metal particles pass through the most sensitive region, therefore the sensitivity of inductance detection is enhanced. And the cross-sectional area of the microchannel increases, so the throughput is higher. For the inductance detection, the signal-to-noise ratio initially increases with the coil turns, but then it has a tendency to decrease. For the capacitance detection, the signal-to-noise ratio decreases with the coil layers. We used the coil with 40 turns, which can ensure the detection sensitivity of the inductance detection and the capacitance detection, to explore the floor level of chip. We successfully detected 40 μm iron particles, 125 μm copper particles, 60 μm water droplets and 120 μm air bubbles.

A multi-parameter on-chip impedance sensor for the detection of particle contamination in hydraulic oil

The invention provides an annular micro-flow channel oil liquid detection device and a manufacturing method thereof. The device comprises a micro-fluidic sensor and a measuring unit. According to different magnetization effect mechanisms of ferromagnetic particles and non-ferromagnetic particles in a spatial magnetic field, the device is used for detecting solid pollutants in oil liquids such as hydraulic oil, lubricating oil and the like. The attributes of the pollutants are distinguished by utilizing an inductance detection method. An annular micro-flow channel is designed for the first time, so that the flux of a to-be-detected oil sample is increased, and the detection time is shortened; and a silicon steel sheet is placed in the micro-flow channel, and the spatial magnetic field of adetection area is gathered, so that the magnetic field intensity of the detection area is increased, and the detection precision of the sensor is improved. The method and the process have the advantages that the manufacturing is simple and reliable, and the cost is reduced. An effective method is provided for oil liquid online monitoring of machine equipment, and fault diagnosis can be carried outon the machine equipment.

Annular micro-flow channel oil liquid detection device and manufacturing method thereof

The invention provides a high-sensitivity hydraulic oil liquid detection device and a manufacturing method thereof. The high-sensitivity hydraulic oil liquid detection device is used for distinguishing and detecting grain pollutants including ferromagnetic metal grains, non-ferromagnetic metal grains, water drops, bubbles and the like in oil liquid. According to the manufacturing method of the device, two plane coils and two solenoid coils are combined and embedded into a microfluidic chip for the first time based on a microfluidic chip technology; the two plane coils are laminated and the solenoid coils are symmetrically arranged at two sides respectively; two silicon steel sheets are added into the two solenoid coils respectively, so that the detection sensitivity of the device is remarkably improved. According to the chip, one sensor unit is used for carrying out voltage detection, so that various grain pollutants in lubricating oil and hydraulic oil are distinguished and detected;a feasible method is provided for online monitoring of the oil liquid through machine equipment and fault diagnosis can be carried out on the machine equipment.

High-sensitivity hydraulic oil liquid detection device and manufacturing method thereof

The invention provides a planar inductive abrasive particle monitoring device and a manufacturing method thereof. The device includes a sensing device, a power unit, an observation unit, an excitation-detection unit and a data processing unit, wherein the sensing device, the power unit, the observation unit, the excitation-detection unit and the data processing unit are electrically connected, during use, oil with abrasive particles is injected by the power unit into the sensing device, an alternating current is applied by the excitation-detection unit for excitation to a planar induction coil, an inductance signal measured by the planar induction coil is detected, the inductance signal is transmitted to the data processing unit through an analog to digital converter, and inductance signaldata is processed and analyzed by the data processing unit to obtain the information of the abrasive particles. The device is advantaged in that through attaching the planar induction coil to an annular silicon steel sheet, the planar induction coil is made to be more sensitive to detect the metal abrasive particles, detection accuracy is improved, accurate monitoring of a hydraulic system can beperformed, the oil is changed in time, failure occurrence is prevented, and fault diagnosis of the machine equipment is performed.

Gu Changzhi

Papers

A multi-parameter on-chip impedance sensor for the detection of particle contamination in hydraulic oil

Annular micro-flow channel oil liquid detection device and manufacturing method thereof

High-sensitivity hydraulic oil liquid detection device and manufacturing method thereof

Planar inductive abrasive particle monitoring device and manufacturing method thereof