JPH0375816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composite sensor for detecting bearing failure, which detects failure based on the temperature change rate, vibration, etc. of the bearing.

[Prior Art] Conventionally known bearing abnormality monitoring devices often determine whether the bearing is normal or abnormal based on information regarding the temperature or vibration of the bearing. Most of them simply set a threshold value of the temperature or vibration level + α value under normal conditions, and when the input signal value exceeds this threshold, a signal is issued to notify of an abnormality, or the machine is operated. The idea is to stop.

On the other hand, the rate of temperature change, that is, the rate of temperature change, can also be effectively used to monitor abnormalities in the bearing. This temperature change rate is a differential value of temperature with respect to time, and can be determined digitally or electrically. If this information is used as information for temperature control, etc., it is possible to predict future trends in temperature change, and therefore it is possible to make early decisions regarding abnormal temperature rises, etc.

However, digitally differentiating signals generally requires expensive equipment, and electrically differentiating signals requires an electrical differentiation circuit that is susceptible to noise. Addressing these issues, Nara et al.
We have developed a temperature change rate sensor as shown in Figure 5 (Nara, Tamura: see the proceedings of the 45th Annual Meeting of the Japan Society of Applied Physics in 1984 and the 46th Academic Conference of the Japan Society of Applied Physics in 1985). Structurally, the sensor has a cylindrical cross section as shown in the figure, with a head 1 that touches the object to be measured, a link 2 attached to the head, a tail 3 attached to the tip of the link, and an internal It consists of a cover 4 that maintains a vacuum and thermally isolates it from the outside. In this case, the temperature difference between head 1 and tail 3 is approximately proportional to the rate of change of the temperature of head 1 over time. To measure the temperature difference between head 1 and tail 3, a series thermocouple with a hot junction and a reference junction placed at head 1 and tail 3, respectively, is used.

This temperature change rate sensor, as mentioned above,
Although it can be effectively used to detect abnormal temperature rises in bearings, it is still not possible to effectively detect abnormalities in bearings by simply detecting the rate of temperature change. It becomes necessary.

[Problems to be Solved by the Invention] A technical problem of the present invention is to use the temperature change rate sensor described above and make it possible to detect vibration and temperature by slightly modifying it, thereby detecting bearing failures at an early stage. The objective is to obtain a composite sensor for bearing failure detection that makes discovery possible.

[Means for Solving the Problems] In order to solve the above problems, the temperature change rate sensor of the present invention is provided by attaching a link with a tail at the tip in the form of a cantilever to the head that touches the object to be measured.
The above link and tail serve as springs and masses that constitute a vibrator for detecting vibrations, and are thermally isolated from the outside by a cover, measuring the temperature difference between the head and tail, and at the same time functioning as a thin metal wire strain gauge. A thermocouple group is attached to the surface of the link, and a part of the thermocouple group is configured to be usable for temperature detection.

[Operation] If the head of the composite sensor is operated with the head attached to or near a part of the bearing, and the temperature difference between the head and the tail is measured as the temporal rate of change in the temperature of the head using a group of thermocouples, it is possible to Before the temperature reaches a certain dangerous temperature, it is possible to predict the point in time when the temperature will reach a certain dangerous temperature and issue a warning or reduce the load.

Additionally, if the thermocouple group is used as a thin metal wire strain gauge to detect the vibration of the vibrator made up of links and tails at the same time as the above temporal temperature change rate, the same measures as above can be taken due to abnormal vibration. becomes possible.

Furthermore, if the temperature of the bearing gradually increases and reaches a dangerous temperature, the temperature can be detected by some of the thermocouples, and similar measures can be taken if the temperature exceeds a certain threshold. .

[Embodiment] FIGS. 1 to 4 show an embodiment of a composite sensor for bearing failure detection according to the present invention.

This composite sensor for bearing failure detection is designed to detect bearing failure early, and is capable of detecting the temperature change rate, vibration, and even temperature of the bearing with a single sensor. In other words, by knowing the rate of temperature change around the bearing, it is possible to predict that the temperature of the bearing, etc. will reach the dangerous temperature after a certain period of time, before the temperature reaches the dangerous temperature. If the vibration is abnormally large even if there is no risk of reaching a dangerous temperature, a signal indicating that there is an abnormality is output. Furthermore, if the temperature rises very gradually but continuously and reaches a dangerous temperature, it cannot be detected using the above temperature change rate, so a thermocouple that measures the temperature change rate can be used to measure the temperature in proportion to the temperature. It outputs a signal.

As shown in Figures 1 and 2, the sensor for detecting bearing failure has a structure in which a flat link 12 with a tail 13 at its tip is attached in a cantilevered manner to a head 11 that touches the object to be measured. , cover them airtight with a cover 14 to keep the inside vacuum,
It is thermally isolated from the outside. The link 12 and tail 13 function as a spring and mass that constitute a vibrator for detecting vibrations.

To measure the temperature difference between the head 11 and the tail 13, which is approximately proportional to the temporal rate of change in the temperature of the head 11, as shown in FIG. By attaching and connecting them as shown in FIG. 4, a DC voltage proportional to the temperature difference between the head 11 and the tail 13 generated in the thermocouple groups 15a to 15b can be measured by the voltmeter 16.
At the same time, these thermocouple groups 15a to 15d are connected via a Wheatstone bridge and used as a thin metal wire strain gauge using an AC carrier wave. is a spring and the tail 13 is a mass so that the vibration of the vibrator can be detected. Further, one element 17 of the same thermocouple group is used for temperature detection and is connected to a thermocouple thermometer.

Note that the DC component flowing through the Wheatstone bridge for strain measurement is connected to external capacitors 18 and 1.
8, and in the voltmeter 16 for measuring the temperature change rate, the effects of the alternating current component of the carrier wave and noise are removed by averaging.

The thermal characteristics of the sensor described above are determined by the cross-sectional area and length of the link 12, the volume of the tail 13, the specific heat, and their thermal conductivity, and are also important characteristics as a vibrator for vibration measurement. The frequency is determined by the moment of inertia of the link 12, its length, modulus of longitudinal elasticity, and the moment of inertia of the tail 13 relative to the head portion. Although these values may not always satisfy the conditions required for the above-mentioned sensor, depending on the relationship between the vibration frequency to be measured and the natural frequency of the sensor, it is possible to use the acceleration type, velocity type, or displacement type depending on the relationship between the vibration frequency to be measured and the sensor's natural frequency. This makes it possible to use the sensor not only for precision measurements but also as a sensor for detecting bearing failures.

Note that it is advantageous to use vapor deposition, sputtering, and etching methods to manufacture the thermocouple groups 15a to 15d.

The composite sensor having the above configuration is used with its head 11 attached to a part of the bearing or in the vicinity, for the purpose of early detection of bearing failure.
By measuring the temperature difference between the head 11 and the tail 13 with the voltmeter 16 described above as a time rate of change in the temperature of the head 11, it is possible to approach the dangerous temperature before the temperature of the bearing etc. reaches the dangerous temperature. It becomes possible to take measures such as emitting a warning or reducing the load by anticipating this.

In addition, at the same time as the above temperature change rate, the thermocouple group 15
Using a to 15d as thin metal wire strain gauges,
By detecting the vibration of the vibrator made up of the link 12 and the tail 13, even if there is no risk of the bearing reaching a dangerous temperature, it is possible to take the same measures as above if the vibration is abnormally large. becomes.
In order to detect this vibration, it is necessary to attach the sensor to the bearing so that the flat surface of the flat link 12 is orthogonal to the direction of vibration.

Furthermore, if the temperature of the bearing increases very gradually but continuously and reaches a dangerous temperature, it is impossible to detect an abnormality based on the temperature change rate, so only one series thermocouple is used to set the reference junction to room temperature or zero temperature. A signal proportional to temperature is extracted as a signal, and if the temperature exceeds a certain threshold, an alarm is issued.
It is possible to take measures such as reducing the load.

[Effects of the Invention] According to the composite sensor for bearing failure detection of the present invention described in detail above, a temperature change rate sensor capable of measuring the temperature difference between the head and the tail as a temporal rate of change in the head temperature is used. By making some modifications to it, it is now possible to detect vibrations and temperature as well.
Bearing failures can be detected early.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the composite sensor for detecting bearing failure of the present invention, FIG. 2 is a plan sectional view thereof,
FIG. 3 is a sectional view of the link in the above embodiment, FIG. 4 is an explanatory diagram showing the circuit configuration of a thermocouple group attached to the link, and FIG. 5 is a sectional view showing the configuration of a known temperature change rate sensor. be. 11...Head, 12...Link, 13...Tail, 14...Cover, 15a to 15d...Thermocouple group.

Claims (1)

[Claims] 1 A link with a tail at the tip is attached in a cantilevered manner to the head that touches the object to be measured, and the link and tail are used as a spring and mass that constitute a vibrator for detecting vibrations, and are covered with a cover. A thermocouple group that is thermally isolated from the outside and functions as a thin metal wire strain gauge while measuring the temperature difference between the head and tail can be attached to the surface of the link above, and a part of the thermocouple group can be used for temperature detection. A composite sensor for bearing failure detection characterized by: