JPH1078411A - Method and device for measuring magnetic powder concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for measuring magnetic powder concentration wherein accurate zero point correction is automatically performed regardless of zero point correction sense of an operator even in the case where a lubricant to be inspected of change of circumferential temperature and high temperature is measured as a sample, and magnetic powder concentration can be always accurately measured by performing measurement in a stable state. SOLUTION: A detection coil L3 is disposed in the magnetic path of an exciting coil 1 capable of inserting a magnetic powder mixed sample S, and magnetic powder concentration contained in the sample S is found on the basis of induced voltage induced in the detection coil L3. At the time when insertion and non-insertion states of the sample S in the exciting coil L1 are detected the non-insertion state is detected, zero point correction data are found, and at the time when the insertion stated is detected, zero point correction is automatically performed on the basis of the zero point correction data found just before detection. Magnetic powder concentration is found on the basis of the induced voltage induced in the detection coil L3 at a time point when insertion of the sample S is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention indirectly diagnoses deterioration such as abrasion damage of bearings of various machines by measuring the concentration of magnetic powder such as iron powder mixed in lubricant such as lubricating oil or grease. More specifically, the method and apparatus for measuring the concentration of magnetic powder to be described will be described in detail. To be more specific, a sample mixed with magnetic powder can be inserted into at least one of an excitation coil or a detection coil arranged in a magnetic path of the excitation coil, and the detection coil The present invention relates to a method and an apparatus for measuring the concentration of magnetic powder contained in a sample, based on an induced voltage induced in the sample.

[0002]

2. Description of the Related Art Conventionally, as a magnetic powder concentration measuring device, a measuring means configured to insert a sample mixed with magnetic powder into at least one of an excitation coil and a detection coil arranged in a magnetic path of the excitation coil, A processing means for outputting the concentration of the magnetic powder contained in the sample based on the induced voltage induced in the detection coil, and a manual operation unit for zero correction are configured, and the measurer places the sample on the coil. Prior to insertion, the measurement was performed after the zero point was corrected by operating the manual operation unit. Here, the mechanism for zero point correction includes adjustment of the reference voltage of the operational amplifier for amplifying the output from the detection coil, adjustment of the offset voltage, and subtraction processing of the zero point fluctuation after the output stage of the operational amplifier. The manual operation unit is configured with a volume, a switch, and the like for operating the mechanism for zero point correction described above.

[0003]

In the above-described conventional magnetic powder concentration measuring apparatus, the zero point fluctuates due to a change in impedance of the coil due to a change in the ambient temperature of the apparatus and a temperature characteristic of a circuit element constituting the processing means. In addition, the reliability of the measured value cannot be compensated unless the zero point is adjusted by operating the manual operation unit for zero correction prior to the measurement.However, the operation of manually performing the zero correction at each measurement is extremely troublesome. Yes, I often forgot to operate the manual operation unit. Furthermore, when collecting a test lubricant, which is a sample, from a rotating machine or the like, since the temperature of the lubricant is higher than the ambient temperature, measured values are taken for a long time until the temperature of the lubricant decreases to the ambient temperature. There was a disadvantage that it was not stable. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for measuring the concentration of a magnetic powder, which can more easily and accurately measure in view of the above-mentioned conventional problems.

[0004]

In order to achieve this object, a first characteristic configuration of the magnetic powder concentration measuring method according to the present invention is as described in claim 1 of the claims. A sample mixed with magnetic powder is inserted into at least one of the detection coils arranged in the magnetic path of the exciting coil, and the concentration of the magnetic powder contained in the sample is determined based on an induced voltage induced in the detection coil. A method for measuring the concentration of magnetic powder to be determined, wherein the insertion of the sample into the coil, a non-insertion state is detected, and when the non-insertion state is detected, zero point correction data is obtained and the insertion state is detected. Sometimes, the zero correction is automatically performed based on the zero correction data obtained immediately before the detection. A second characteristic configuration of the magnetic powder concentration measuring method according to the present invention is, as described in claim 2 of the claims section, in addition to the above-described first characteristic configuration, insertion of the sample into the coil. Is completed, or the concentration of the magnetic powder contained in the sample is determined based on the induced voltage induced by the detection coil at the time when a predetermined time has elapsed after the insertion of the sample into the coil. Furthermore, the first characteristic configuration of the magnetic powder concentration measuring device according to the present invention is, as described in claim 3 of the claims section, at least one of an excitation coil and a detection coil arranged in a magnetic path of the excitation coil. On the other hand, a magnetic powder comprising: a measuring means configured to be able to insert a sample mixed with magnetic powder; and a processing means for outputting the concentration of magnetic powder contained in the sample based on an induced voltage induced in the detection coil. A concentration measuring apparatus, wherein the sample is inserted into the coil, sample detection means for detecting a non-insertion state, and input zero point correction data when the non-insertion state is detected,
When the insertion state is detected, a correction means for automatically performing zero correction based on zero point correction data input immediately before the detection is provided. The second characteristic configuration of the magnetic powder concentration measuring apparatus according to the present invention is, as described in claim 4 of the claims section, in addition to the above-mentioned first characteristic configuration, the processing means further comprises: At the time when the insertion into the coil is completed, or after the insertion of the sample into the coil, the concentration of the magnetic powder contained in the sample is determined based on the induced voltage induced by the detection coil at the time when a predetermined time has elapsed. The point is that it is configured so as to be obtained. The third characteristic configuration of the magnetic powder concentration measuring device according to the present invention is, as described in claim 5 of the claims section, in addition to the above-described first or second characteristic configuration, A pair of excitation coils connected in series is arranged so that the magnetic fields of the respective excitation coils face each other, and a detection coil is arranged at a position where the combined magnetic field of the pair of excitation coils becomes zero. The point is that the sample in which the magnetic powder is mixed into the coil is configured to be freely inserted and removed.

The operation will be described below. The correction means
When the sample detection means detects that the sample has not been inserted into the coil, zero point correction data, that is, data for making the output of the detection coil zero, is input constantly or periodically. When the insertion of the sample into the coil is detected by the sample detection means, the zero point is automatically corrected based on the zero point correction data input immediately before, regardless of whether the operator is conscious of zero point correction. . Therefore, appropriate zero correction is always performed at the time of measurement. The measurement by the processing means should be performed after the sample is securely inserted into the coil.However, when it cannot be accurately determined whether or not the sample has been securely inserted, or as described above, the sample is collected from a rotating machine or the like. When the sample, which is the high-temperature test lubricant, is inserted into the coil, the ambient temperature of the coil may fluctuate and the zero point may fluctuate. In such a case,
The output of the device fluctuates from time to time, making it difficult for an operator to read the output. Therefore, when the insertion of the sample into the coil is completed, or after the insertion of the sample into the coil,
When the predetermined time has elapsed, the concentration of the magnetic powder contained in the sample is obtained based on the induced voltage induced by the detection coil, so that the concentration of the magnetic powder can be accurately measured.
Here, the time when the insertion of the sample into the coil is completed, or the time when a predetermined time has elapsed after the insertion of the sample into the coil,
For example, when the insertion of the sample is detected by the detection means, when the stability of the measured magnetic powder concentration value is confirmed,
This refers to a point in time when a predetermined time has elapsed from the point in time when the insertion of the sample is detected by the detection means. As detection means, a pair of excitation coils connected in series, and arranged so that the magnetic field of each excitation coil is opposed, and a detection coil is disposed at a position where the combined magnetic field by the pair of excitation coils becomes zero, If a sample containing magnetic powder mixed into one of the excitation coils can be inserted and removed freely, there will be local temperature fluctuations in the excitation coil on the side where the high-temperature sample is inserted, and the excitation current will change due to changes in internal resistance. However, since the pair of exciting coils are connected in series, the exciting current of the other exciting coil also changes, so that the magnetic balance does not fluctuate. Therefore, the fluctuation factor of the zero point can be reduced. It is. As a result, even when a test lubricant higher than the ambient temperature is collected from the rotating machine, the magnetic powder concentration can be measured accurately without waiting for the lubricant temperature to stabilize.

[0006]

Therefore, according to the present invention, even when the ambient temperature changes or a high-temperature lubricant to be measured is measured as a sample, it is automatically accurate regardless of the operator's awareness of zero point correction. Since the zero point correction is performed and the measurement is performed in a stable state, it is possible to provide a magnetic powder concentration measuring method and a device capable of always accurately measuring the magnetic powder concentration. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the magnetic powder concentration measuring method and apparatus according to the present invention will be described below. As shown in FIG. 1, the magnetic powder concentration measuring device includes a pair of equivalent exciting coils L1 and L2 connected in series inside a housing 1,
The magnets are arranged on a vertical common axis P so that the magnetic fields generated by the exciting coils L1 and L2 face each other.
Above, the detection coil L3 is disposed such that the combined magnetic field by the pair of excitation coils L1 and L2 becomes zero, that is, the common axis P and the axis overlap at the center of both coils L1 and L2. A pair of exciting coils L1, L2 and the detecting coil L3 are surrounded by a magnetic shield member to constitute a measuring means, and a power supply means 2 for supplying an exciting current to the exciting coils L1, L2 is provided. Processing means 3 for calculating and deriving the magnetic powder concentration from the output signal of the coil L3 is provided. An insertion hole 1a for inserting a non-metallic sample container made of glass, resin or the like in which the sample S mixed with the magnetic powder is sealed is formed on the upper surface of the housing 1, and the insertion hole 1a is inserted through the insertion hole 1a. The sample container is inserted into one of the excitation coils L1 immediately below the insertion hole 1a in a state where the flange formed at the upper end is supported on the upper surface of the support portion 1b of the housing 1. Excitation coil L1
Is arranged. Further, the support portion 1b is provided with a sample detecting means 4 composed of a photoelectric sensor, and is configured to be able to detect whether the sample container is inserted into or not inserted into the exciting coil L1. Incidentally, the sample detecting means 4 can be constituted by a mechanical sensor such as a micro SW other than the photoelectric sensor.

The power supply means 2 comprises a power supply circuit 2a,
A transmitting circuit 2b for outputting an AC exciting current of about 30 kHz to 200 kHz;
Is a first amplifier circuit 3a for amplifying the output signal of the detection coil L3, and a synchronous detection circuit 3 for synchronously detecting the amplified signal with the output signal of the transmission circuit 2b and outputting a DC voltage.
b, a second amplification circuit 3c for amplifying the output of the synchronous detection circuit 3b, an A / D conversion circuit 3d for quantizing the signal amplified by the second amplification circuit 3c, and a predetermined conversion of the quantized data. An arithmetic processing unit 3e for calculating and deriving the concentration of the magnetic powder contained in the sample S based on the equation; and a driving unit for driving the sample detecting unit 4 to detect a detection signal of the sample container from the sample detecting unit 4 in the arithmetic processing unit. A sample detecting means driving unit 3g input to the sample processing unit 3e and a display unit 3f using, for example, a liquid crystal for displaying the calculation result by the calculation processing unit 3e. A change in magnetic balance due to a change in the magnetic permeability inside the excitation coil L1 according to the concentration is obtained by measuring the induced voltage of the detection coil L3, and is converted into the concentration of the magnetic powder contained in the sample S.

The detection coil L3 is screwed with a ferrite core as an iron core FC having a thread formed on a peripheral portion thereof. The sample S is not inserted into the excitation coil L1 or is inserted. When an induced voltage is generated in the detection coil L3 due to a displacement of the detection coil L3 in a state where the sample S does not include the magnetic powder, the position of the detection coil L3 is changed in a manufacturing stage. The zero point can be easily adjusted by adjusting the position of the iron core FC in the direction of the axis P, and the detection coil L3
It is configured to reduce the magnetic resistance inside and improve the detection sensitivity. Note that a self-resetting type span adjustment switch (not shown) is attached to the housing 1, and a signal thereof is input to the arithmetic processing unit 3 e.

Hereinafter, a method of using the above-described magnetic powder concentration measuring device will be described with reference to a flowchart shown in FIG. When the power switch (not shown) of the device is turned on,
First, the A / D conversion circuit 3d to the arithmetic processing unit 3e
Then, the data of the detection coil L3 input to (1) is input (S1). In a state where the insertion of the sample container is not detected by the sample detecting means 4 (S2), the input data is stored as zero point correction data in a storage circuit (not shown) provided in the arithmetic processing unit 3e, The display unit 3
The magnetic powder concentration is displayed as "0%" in f (S3, S4).
The input of the zero point correction data is performed every predetermined time, for example, every several hundred milliseconds, and is always updated to the latest data. this is,
This is to correct the subsequent fluctuation of the zero point adjusted by adjusting the position of the iron core FC in the manufacturing stage and the fluctuation caused by the environmental temperature of the measuring means and the processing means 3. While the insertion of the sample container is detected by the sample detecting means 4 (S2), it is detected whether or not the span adjustment switch (not shown) is operated. Set (S6). The zero point correction data is subtracted from the input data to perform zero point correction (S7),
If the span adjustment flag is set, the process proceeds to the span adjustment step. More specifically, after turning on the span adjustment switch, the operator sets the reference concentration (magnetic powder concentration 5%).
Is inserted into the excitation coil L1. At this time, a magnetic powder concentration is calculated and derived from the input data after the zero point correction using a predetermined conversion formula, and the result is 5%. Correct the conversion formula so that
Is displayed on the display unit 3f, the magnetic powder concentration is set to "5".
% "And resets the span adjustment flag (S9 to S13). Specifically, voltage data calculated and derived from input data (input voltage) when a reference sample having a concentration of 5% is inserted. If the span adjustment flag has been reset in step S8, it is determined that span adjustment has been completed, and a predetermined conversion formula is applied to the input data after zero correction. Is used to calculate and derive the magnetic powder concentration, and display the result on the display unit 3f (S14, S15) .Data input from the detection coil L3 is performed every several hundred milliseconds (for example, 300 milliseconds). The input of data is repeated while the previous input data and the present input data are fluctuating, and when data having a change amount or change rate of less than a predetermined value is input several times (for example, three times) continuously, the data is stable. did Judgment is made, the density value is stored in a storage circuit (not shown) provided in the arithmetic processing unit 3e, and the stored density value is displayed on the display unit 3f, so that the subsequent input data varies. Even if the display data is not changed, the operator can easily read the data.

Here, the determination as to whether or not the detected density value is stable is based on whether or not the condition that the amount of change or the rate of change of the input data becomes a predetermined value or less several times as described above. Although the measurement should be performed after the sample is securely inserted into the excitation coil, the insertion of the sample container is detected by the sample detection means 4, but the sample is not positioned at a predetermined position. If it is not possible to accurately determine whether or not the plug has been inserted correctly, or if a sample, which is a high-temperature lubricant sample collected from a rotating machine, is inserted into the excitation coil, the ambient temperature of the coil will fluctuate. The zero point may fluctuate, and in such a case, it is to avoid the inconvenience that it becomes difficult for an operator to read an accurate output because the output of the apparatus fluctuates every moment. That is, after the insertion of the sample container is detected by the sample detection means 4, several times (for example, three times), when data in which the amount of change or the rate of change is less than the predetermined value is input continuously, the sample container is detected. Since it is determined that the setting to the predetermined position is completed, the value at that time is held and displayed, and the display data of the density value is prevented from fluctuating due to the fluctuation of the input data due to the subsequent temperature fluctuation. is there.

Therefore, in order to avoid the above-mentioned problems, it is necessary to set the time when the insertion of the sample container into the excitation coil L1 is completed or the time when a predetermined time has elapsed after the insertion of the sample container into the excitation coil L1. The procedure is not limited to the above procedure as long as the density of the magnetic powder contained in the sample is obtained based on the induced voltage induced by the detection coil L3 and the value is held. For example, as shown in FIG. 3, the sample detecting means 4 comprising a photoelectric sensor is connected to the exciting coil L1.
Is arranged on the side of the detection coil L3 so as to be detected at the time when the insertion of the sample container is completed, and the data calculated and derived based on the input data at the time of the detection is provided. You may comprise so that it may hold | maintain. In this case, the zero point correction data may be sampled during the insertion of the sample container.
The second sample detecting means 4 'is provided at the end of the first port and on the side of the insertion port 1a, and data inputted immediately before the detection of the sample container by the second sample detecting means 4' is used as zero point correction data. Is preferred. Further, data calculated and derived based on data input at a time when a predetermined time elapses from the time when the insertion of the sample is detected by the detection means 4 to the time when the setting to the predetermined position is completed is held. You may comprise. When the sample detector 4 detects that the sample container has been pulled out, the process returns to step S1 to prepare for the next measurement (S18).

In the above description, as a mechanism for automatically performing zero point correction, output data of the detection coil L3 input before the sample container is inserted into the excitation coil L1 is sent to the arithmetic processing unit 3e as zero point correction data. In the above description, the zero-point correction data is stored in a storage circuit (not shown) provided, and the zero-point correction data is subtracted from the output data of the detection coil L3 input after the sample container is inserted into the excitation coil L1. In addition to the digital arithmetic processing, a volume for automatically switching and adjusting one of the input voltages so that the second amplifier circuit 3c is constituted by an operational amplifier and its inverted input value is equal to the non-inverted input value. A circuit or a switch circuit may be provided to output a signal for adjustment from the arithmetic processing unit 3e. The above-mentioned magnetic powder concentration measuring device can employ any method as long as it uses the electromagnetic induction method. In addition to the above-described magnetic balance type electromagnetic induction method, as shown in FIG. Alternatively, a simple electromagnetic induction method using a single excitation coil L1 and a single detection coil L3 may be employed, or a single excitation coil may be provided on a common axis as shown in FIG. A differential detection coil type electromagnetic induction method in which the coil L1 is sandwiched between a pair of detection coils L3 and L4 may be employed. Here, in the one adopting the electromagnetic induction method of the magnetic balance type,
One or both of the excitation coil and the detection coil are coils to be inserted into the sample container. In the method shown in FIGS. 4 and 5, only the detection coil is a coil to be inserted into the sample container. In the case where the above-described electromagnetic induction method of the magnetic balance type is employed, a case where the iron core FC is installed in the detection coil L3 so as to be freely adjustable has been described. However, the effect of the present invention can be obtained without the iron core FC. . Further, a pair of equivalent exciting coils L1 and L2 connected in series is connected to each of the exciting coils L1 and L2.
The magnetic field generated by the pair of exciting coils L1 and L2 is located on the vertical common axis P so that the magnetic field generated by the two coils L1 and L2 is zero. Although the detection coil L3 is arranged so that the common axis P and the axis overlap at the center of L2, the excitation coils L1 and L2 are not necessarily equivalent.
That is, the number of turns and the impedance need not be equal. In that case, the pair of exciting coils L1 and L2
The detection coil L3 may be arranged at a position where the combined magnetic field due to is zero. Further, if the exciting coils L1 and L2 are arranged so that the magnetic fields generated by the exciting coils L1 and L2 face each other, it is not always necessary to arrange them on the common axis P. Coil L1, L2
The detection coil L3 may be arranged at a position where the combined magnetic field due to is zero.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a magnetic powder concentration measuring device.

FIG. 2 is a flowchart.

FIG. 3 is a configuration diagram of a magnetic powder concentration measuring apparatus showing another embodiment.

FIG. 4 is a configuration diagram of a magnetic powder concentration measuring apparatus showing another embodiment.

FIG. 5 is a configuration diagram of a magnetic powder concentration measuring apparatus showing another embodiment.

[Explanation of symbols]

 L1, L2 excitation coil L3 detection coil FC iron core M measuring means

Claims (5)

[Claims] 1. A structure in which a sample mixed with magnetic powder is inserted into at least one of an excitation coil and a detection coil arranged in a magnetic path of the excitation coil, and the detection coil is configured to detect the voltage based on an induced voltage induced in the detection coil. A method for measuring the concentration of magnetic powder contained in a sample, comprising: inserting the sample into the coil, detecting a non-insertion state,
Magnetic powder concentration measurement for obtaining zero-point correction data when a non-insertion state is detected and automatically zero-correcting based on the zero-point correction data obtained immediately before the detection when an insertion state is detected. Method. 2. When the insertion of the sample into the coil is completed, or after the insertion of the sample into the coil,
2. The magnetic powder concentration measuring method according to claim 1, wherein a concentration of the magnetic powder contained in the sample is obtained based on an induced voltage induced by the detection coil at a point in time when a predetermined time has elapsed. 3. A measuring means configured to allow a sample mixed with magnetic powder to be inserted into at least one of an exciting coil or a detecting coil disposed in a magnetic path of the exciting coil, and an induced voltage induced in the detecting coil. A magnetic powder concentration measuring device comprising: a processing unit that outputs a magnetic powder concentration contained in the sample based on the sample detection unit that detects a state of insertion and non-insertion of the sample into the coil; Correction means is provided for inputting zero correction data when the insertion state is detected, and automatically performing zero correction based on the zero correction data input immediately before the detection when the insertion state is detected. A magnetic powder concentration measurement device. 4. The induction induced by the detection coil at a time when the insertion of the sample into the coil is completed or at a time when a predetermined time has elapsed after the insertion of the sample into the coil. 4. The apparatus according to claim 3, wherein a concentration of the magnetic powder contained in the sample is determined based on a voltage.
The magnetic powder concentration measuring device as described in the above. 5. The sample detecting means arranges a pair of excitation coils connected in series so that magnetic fields generated by the respective excitation coils face each other, and is located at a position where a combined magnetic field generated by the pair of excitation coils becomes zero. 5. The magnetic powder concentration measuring device according to claim 3, wherein a detection coil is arranged, and a sample mixed with magnetic powder is freely inserted into and removed from one of the excitation coils.