JPH08271417A - Apparatus for measuring deterioration of oil - Google Patents

Abstract

PURPOSE: To measure the extent of deterioration of oil accurately regardless of the individual difference among detectors by providing means for blocking the incidence of infrared rays on an infrared detector for the time required for measurement or longer. CONSTITUTION: After chopping infrared rays, an optical path switching plate 15 switches the optical path to 1) block incidence of the infrared rays on detectors 24, 26, 2) pass the infrared rays through a sample cell 21 thence through the detectors 24, 26, or 3) pass the infrared rays through a reference cell 20 thence through the detectors 24, 26. The switching is made at an interval longer than the time required for effecting accurate measurement through the detectors 24, 26. Background value of the detector is then subtracted from the outputs of the detectors 24, 26 obtained by measuring the infrared rays passing through the sample cell and the reference cell. The corrected value is compared the values passed through the sample cell and the reference cell for each output from the detectors 24, 26 thus determining the extent of deterioration of oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the degree of deterioration of oil such as turbine oil of a generator and lubricating oil of an internal combustion engine.

[0002]

2. Description of the Related Art Since a turbine of a generator has to continuously rotate at a high speed for an extremely long time, its lubricating oil must be controlled so that it is always in an optimum state. For example, various additives have been added to lubricating oils used in generator turbines to prevent deterioration due to oxidation, etc. Whether the content of these additives is always within the specified range. It is necessary to take measures such as adding the shortage so that it falls within a predetermined range if it is insufficient.

When inspecting this lubricating oil, an oil deterioration measuring device is used. The structure and operation of a conventional oil deterioration measuring device will be described with reference to FIG. The infrared light generated by the light source 11 is collimated by the parabolic mirror 12 and is narrowed to a predetermined range by the slit 13. The infrared rays that have passed through the slit 13 are chopped by the chopper 14 at a predetermined short cycle (for example, about 1 Hz). As will be described later, since this oil deterioration measuring device uses a pyroelectric element as an infrared detector, chopping of infrared rays is required, and it is not necessary when other infrared detectors are used. There is also. The chopper 14 includes, for example, a passing portion 14a and a blocking portion 14b as shown in FIG.
Are composed of discs alternately arranged, and the infrared rays are interrupted by rotating the discs at an appropriate rotation speed (300 rpm in the above case).

The infrared rays interrupted by the chopper 14 are
The optical path switching plate 15 causes the optical path 17 toward the reference cell 20.
And is sent to one of the optical paths of the optical path 16 toward the sample cell 21. For example, as shown in FIG. 4B, the optical path switching plate 15 is made of a disk in which transmissive portions 15a and reflective portions 15b are alternately arranged. When the transmissive portion 15a is placed in front of the slit 13, infrared rays are emitted from the sample cell 21. Is sent to the optical path 16 to the optical disc, the disc is rotated 90 °, and the reflecting portion 15b is slit 13.
When placed in front of the infrared light is sent to the optical path 17 to the reference cell 20.

The case where infrared rays pass through the optical path switching plate 15 will be described first. The infrared rays are irradiated onto the sample cell 21 by the reflecting mirror 18 and pass through the oil to be measured filled in the cell (or flowing in the cell). At this time, infrared rays are absorbed at a wavelength corresponding to each component of the oil to be measured and its additive. The infrared light that has passed through the sample cell 21 is split by a half mirror 22 into straight light and reflected light. The straight light is sent to a first infrared detector 24 and the reflected light is sent to a second infrared detector 26. A band-pass filter (BPF) 23 is provided at the entrance of the first infrared detector 24 to pass only the absorption wavelength λ1 of the component that serves as an index of oil deterioration, and the entrance of the second infrared detector 26 is provided at the entrance. A bandpass filter 25 that passes only the absorption wavelength λ2 that is unrelated to oil deterioration.
Is provided. Therefore, by comparing the outputs of the infrared detectors 24 and 26, the degree of deterioration of the oil to be measured can be temporarily measured.

However, since the infrared rays that have passed through the sample cell 21 pass through not only the oil to be measured but also the glass wall of the container of the sample cell 21 and the like, it is not possible to accurately measure the degree of deterioration only by the above measurement results. . Therefore, the optical path switching plate 15 is rotated by 90 °, the infrared light of the same light source 11 is reflected, and this time the reference cell 20, which is the same cell as the sample cell 21, is passed. Air or clean oil is put in the reference cell 20. After that, the specific wavelengths λ1 and λ2 selected by the bandpass filters 23 and 25 are the same as above.
The intensity of the infrared rays of the above is measured by both infrared detectors 24 and 26. By correcting the measured value using this strength value, the deterioration degree of the measured oil can be measured.

In the above description, the turbine oil of the generator is taken as an example, but the oil deterioration measuring device can be used for measuring deterioration of lubricating oil of other general machines.

[0008]

An infrared detector used in such an oil deterioration measuring device outputs a current only when an infrared ray to be measured is incident, and the output is zero when no infrared ray is incident. Ideally, the actual detector outputs a small current (dark current) even when no infrared ray is incident. In particular, in the case of an infrared detector using a pyroelectric element, this dark current has a magnitude that cannot be ignored. Since the value of the dark current generally differs for each infrared detector, in the configuration of the conventional oil deterioration measuring device as described above, the individual difference of the infrared detector may affect the deterioration measuring value. There is.

The present invention has been made to solve such a problem, and its purpose is to eliminate the influence of the dark current of the infrared detector, and to avoid the influence of individual difference of the detector. An object is to provide a device capable of measuring the degree of oil deterioration.

[0010]

SUMMARY OF THE INVENTION An oil deterioration measuring apparatus according to the present invention made to solve the above-mentioned problems is a measurement time required for an infrared detector to measure infrared rays from a light source between a sample optical path and a reference optical path. By switching at the above time intervals so that the infrared rays pass through the oil to be measured only in the sample optical path, measure the intensity of the infrared rays that have passed through both optical paths with an infrared detector, and measure the deterioration degree of the oil by comparing. The oil deterioration measuring device is characterized in that it is provided with a means for preventing infrared rays from entering the infrared detector for a time longer than the above measurement required time.

[0011]

[Operation and effect] As described above, all infrared detectors have background output due to dark current, etc., and there are individual differences in their values. Can not do it. In addition, the intensity of any infrared detector cannot be accurately measured unless the infrared ray is measured for a certain time (this is called the measurement required time) depending on the principle of the infrared measurement. . Therefore, when the infrared light from the light source is sent to the sample optical path or the reference optical path, the infrared light must be sent for a time longer than the measurement required time, and in the dark current measurement, the infrared ray does not enter for the time longer than the measurement required time. If the state is not maintained, stable background output cannot be obtained. In the oil deterioration measuring device according to the present invention, since means for preventing the infrared rays from entering the infrared detector for a time longer than the required measurement time is provided, by measuring the output of the infrared detector during this period, The ground value can be grasped correctly. Therefore, by subtracting the background value thus measured from the output value measured for the infrared rays that have passed through the sample optical path and the reference optical path, it is possible to measure the correct oil deterioration degree in which the individual difference of the infrared detector is corrected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the oil deterioration measuring device according to the present invention will be described with reference to FIGS. The basic configuration of the oil deterioration measuring device of this embodiment is the same as that of the conventional device described above, but the optical path switching plate 15 is not limited to the transmitting portion 15a and the reflecting portion 15b as shown in FIG. 4B. As shown in FIG. 3 (a), it also has a blocking section 15 c. The blocking unit 15c is
This is a portion that does not send the infrared light that has passed through the slit 13 and is chopped by the chopper 14 to any of the sample optical path 16 and the reference optical path 17 and blocks it there. It should be noted that the blocking portion 15c may be coated with a paint that sufficiently absorbs infrared rays, and as shown in FIG. 3 (b), the inclination of the surface of that portion is changed so that the infrared rays can pass through both optical paths 16 and 17. You may make it reflect in directions other than. Further, not only the rotary type but also the parallel moving type as shown in FIG. Further, a plate for blocking infrared rays may be provided separately from the optical path switching plate 15 so as to move it in and out of the optical path, or the slit 13 may be movable so that the slits 13 block the infrared rays. Good.

A method of using the oil deterioration measuring apparatus of this embodiment will be described with reference to FIG. First, the oil to be measured is put (or allowed to flow) in the sample cell 21, and new oil is put in the reference cell 20. The light source 11 is turned on, the chopper 14 is rotated at the speed (300 rpm), and the blocking portion 15c of the optical path switching plate 15 is placed in front of the slit 13. As a result, infrared rays are not sent to either the sample optical path 16 or the reference optical path 17, and the infrared detector 2
Infrared rays do not enter 4 and 26. In this state, the required measurement time t0 of the infrared detectors 24 and 26 (depending on the accuracy required for the oil deterioration measurement, for example, in the case of an infrared detector using a pyroelectric element, about several tens of seconds) Just hold. As a result, the states of both infrared detectors 24 and 26 are stabilized, and the background current is stably output from both detectors 24 and 26. This value (background value) is stored for each of the detectors 24 and 26.

Next, the optical path switching plate 1 shown in FIGS. 3 (a) and 3 (b).
In the case of 5, the optical path switching plate 1 of FIG.
In the case of 5, the transparent portion 1 is moved by moving a predetermined distance.
5a is placed in front of the slit 13 and infrared rays are sent to the sample optical path 16. As a result, the infrared rays pass through the oil to be measured in the sample cell 21 and enter both infrared detectors 24 and 26. Finally, the optical path switching plate 15 is further rotated or moved in parallel so that the reflection portion 15b comes to the front of the slit 13 and infrared rays are sent to the reference optical path 17. This causes the infrared light to pass through the new oil in the reference cell 20 and enter both infrared detectors 24, 26. At the time of measuring these infrared rays, the infrared rays are made to enter the detectors 24 and 26 for a required measurement time t0 or more (FIG. 2).

Each detector 24 obtained by measuring the infrared ray passing through the sample cell and the infrared ray passing through the reference cell,
From the output of 26, the background value stored as described above is subtracted. By comparing the value after performing the background correction in this way for each output of each detector 24, 26 (that is, for each wavelength λ1, λ2) between the sample cell passage value and the reference cell passage value, Calculate the degree of deterioration of the measured oil. In the above embodiment, the infrared detectors 24, 2
Although the example in which the pyroelectric element is used has been described in No. 6, even when other types of infrared detectors are used, the present invention is similarly applied to provide a time when infrared rays do not enter the detector at all. With, background correction can be performed. If another type of infrared detector is used, the chopper 14 may be unnecessary.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an oil deterioration degree measuring apparatus that is an embodiment of the present invention.

FIG. 2 is a time chart showing how to use the oil deterioration measuring device of the embodiment.

3A and 3B are a plan view and a side view showing three types of optical path switching plates used in the oil deterioration measuring apparatus of the embodiment.

FIG. 4 is a plan view of a chopper and an optical path switching plate used in a conventional oil deterioration measuring device.

[Explanation of symbols]

11 ... Light source 12 ... Parabolic mirror 13 ... Slit 14 ... Chopper 15 ... Optical path switching plate 16 ... Sample optical path 17 ... Reference optical path 18, 19 ... Reflector 20 ... Reference cell 21 ... Sample cell 22 ... Half mirror 23, 25 ... Band pass filter 24, 26 ... Infrared detector t0 ... Required measurement time

Claims (1)

[Claims] 1. An infrared ray from a light source is switched between a sample optical path and a reference optical path at a time interval longer than a measurement required time of an infrared detector so that the infrared ray passes through an oil to be measured only in the sample optical path, and both optical paths are provided. In an oil deterioration measuring device that measures the degree of oil deterioration by measuring the intensity of infrared light that has passed through the infrared detector and comparing it, the infrared rays are prevented from entering the infrared detector for a time longer than the above measurement required time. A device for measuring the degree of deterioration of oil, which is provided with a means for doing so.