JPH0631637B2 - Bearing monitor system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor system for detecting the degree of wear of a bearing, and more particularly, to an appropriate amount of wear in the thrust direction of a submerged bearing used in a canned motor pump or the like. Bearing detection system capable of detecting

[Conventional technology]

In general, a canned motor pump has a rotating part that is completely placed in the liquid to be handled, and there is no part that penetrates the liquid contact part and the outside. It completely solves the problem of suction of air and the outside air, and has an excellent advantage as a process pump.

However, the canned motor pump receives all the radial load and thrust load generated by the rotational movement by the bearing, whereas this bearing is lubricated by the handling liquid and the handling liquid and other usage conditions are various. There are various wear modes. Therefore, since it is not possible to determine the bearing expiration date in advance, once the bearing is installed in the plant, it is not possible to know the bearing wear degree unless it is subjected to a periodic inspection or a failure.

From such a point of view, conventionally, as a wear detecting method for this type of bearing, a mechanical means and an electric means have been proposed and implemented. For example, as a mechanical means, an end nut having a cylindrical hole portion concentric with the shaft of the canned motor shaft is provided at the end of the canned motor shaft,
By arranging a detector consisting of a sealed tube with the tip as a sensing part at a position spaced apart from each side surface of the hole of this end nut by a detector, the bearing is worn in the thrust direction or the radial direction, or in the combined direction of both. However, when this exceeds the allowable wear limit, the shaft rotates eccentrically, and at the same time, each side surface of the hole of the end nut and the sensing part of the detector come into contact with each other and the sensing part ruptures, causing any wear of the bearing. It is configured so that it can be surely detected even in the state (Japanese Utility Model Laid-Open No. 58-46852). Further, as an electrical means, a search coil or the like is provided in the stator winding so that the eccentricity of the rotor due to wear of the bearing can be electrically detected by a change in induced current or a change in apparent angle. (Japanese Unexamined Patent Publication No. 52-52952)
-132309).

[Problems to be solved by the invention]

However, as the conventional bearing monitor described above, in the case of using mechanical means, it is possible to reliably detect wear of the bearing in either the thrust direction or the radial direction with one detector, There is a problem in that it is impossible to predict the degree of wear before the sensor bursts, that is, the life of the bearing. Further, although it is possible to detect the amount of wear, that is, to predict the life of the bearing by electrical means, it is limited to only detecting the amount of wear in the radial direction, and therefore the amount of wear in the thrust direction cannot be detected. There is.

Therefore, the object of the present invention is to be able to properly detect the amount of wear in the thrust direction of the bearing, which was conventionally difficult.
Further, in the same manner, it is possible to provide a bearing monitor system which can detect the amount of wear in the radial direction and can be used together with a conventional bearing monitor by mechanical means.

[Means for solving problems]

A bearing monitor system according to the present invention includes a magnetic field generating element provided at one end of a rotary shaft supported by a bearing, and a magnetic sensor provided in the axial direction and / or radial direction of the rotary shaft which is displaced by wear of the bearing. The body is fixedly arranged at a predetermined interval, and a pulse signal having a voltage level proportional to the distance from the rotary shaft is output by the magnetic sensor as the rotary shaft rotates, and this voltage level is compared with a reference voltage level. By the magnetic sensor provided in the axial direction and / or the radial direction, a signal of a change in the axial direction and / or the radial direction of the magnetic field generated by one magnetic generating element for the amount of wear in the thrust direction and / or the radial direction of the bearing is obtained. The feature is that each is detected independently.

Further, in the above bearing monitoring system, the voltage pulse signal detected by the magnetic sensor is superimposed on a reference voltage level of a sawtooth wave of a predetermined cycle that defines the limit of the wear amount of the bearing and compared, and the pulse signal is The bearing position can be detected by dividing the pulse signal according to the reference voltage level and counting the number of pulses of the divided pulse signal per unit time.

[Action]

According to the bearing monitor system of the present invention, the magnetic field generating element is provided at an eccentric position at the end of the rotary shaft supported by the bearing, and the magnetic sensor is held by the sensor holder facing the magnetic field generating element. By arranging them, the magnetic sensor generates a pulse signal having a required voltage level proportional to the distance between the magnetic sensor and the magnetism generating element due to the rotation of the rotating shaft. Therefore, set a reference voltage level that determines the limit distance of the wear amount with respect to the voltage level of this pulse signal,
Moreover, this reference voltage level is superimposed as a sawtooth wave of a predetermined cycle on the pulse signal for comparison, the pulse signal is divided according to the reference voltage level, and the number of pulses per unit time of the divided pulse signal is counted. This makes it possible to properly and easily detect the wear position of the bearing in the thrust direction. In this case, since the magnetic sensor extracts the output signal as a pulse, it is not necessary to align the sensor mounting position with the center of the rotating shaft.

〔Example〕

Next, an embodiment of a bearing monitor system according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 illustrates an example of a bearing monitor system according to the present invention, which is applied to a canned motor constituting a canned motor pump to detect only the wear amount in the thrust direction. In FIG. 1, reference numeral 10
Indicates the rotor shaft of the canned motor.
A thrust washer 12 is provided at each of a front portion (not shown) and a rear end portion of the motor rotor portion of
The rotor shaft 10 is supported by a bearing 14 arranged so as to face the thrust washers 12. The bearing 14 is held by a bearing housing 16 attached to the rear portion of the canned motor, and the bearing housing 16 is configured to surround and seal the rear end portion of the rotor shaft 10. However, an end nut 18 is coaxially provided at the end of the rotor shaft 10, and the sensor holder 20 is made liquid-tight with respect to the bearing housing 16 from the outside by being coaxially opposed to the end nut 18. Insert and place. Therefore, in the present embodiment, a permanent magnet 22 as a magnetism generating element is embedded inside the end nut 18 provided on the rotor shaft 10 so as to face the surface facing the sensor holder 20. On the other hand, also inside the sensor holder 20, the magnetic sensor 24 such as a magnetoresistive element or a Hall element is embedded so as to be directed to the surface facing the end nut 18. In this case, the magnetic sensor 24 is arranged close to the permanent magnet 22 provided on the rotating rotor shaft 10, and the displacement of the rotor shaft 10 in the thrust direction can be detected by the magnitude of the magnetic force. . However, in this case, when the permanent magnet 22 and the magnetic sensor 24 are always opposed to each other and the change in the magnetic force thereof is directly detected, the mounting accuracy of the permanent magnet 22 and the magnetic sensor 24 becomes a problem as the detection accuracy.

Therefore, in the present invention, as shown in the figure, the permanent magnet 2
2 and the magnetic sensor 24 are installed eccentrically with respect to the rotor shaft 10 and the sensor holder 20, respectively.
With the rotation of 0, the magnetic sensor 24 takes out the detection signal as a pulse signal.

Next, the operation of the bearing monitor system of the present embodiment having the above configuration will be described with reference to the characteristic waveform diagrams shown in FIGS. 2 (a), (b) and (c).

First, in FIG. 1, when the bearing 14 is not worn, the separation distance between the permanent magnet 22 and the magnetic sensor 24 is maintained at a set value. At this time, when the canned motor is operated and the rotor shaft 10 rotates, The sensor 24 outputs a pulse signal of a predetermined voltage level proportional to the distance from the permanent magnet 22 [see FIG. 2 (a)]. Therefore,
In this case, the threshold voltage Vs corresponding to the detection voltage of the magnetic sensor 24 for predicting the wear limit is set for the displacement generated in the front-back direction of the shaft due to the wear of the bearings supporting the rotor shaft 10, and this threshold is set. The voltage Vs is superimposed on the output pulse signal of the magnetic sensor 24 as a sawtooth waveform having a predetermined period and compared with the threshold voltage Vs level. At this time, the threshold voltage Vs level is divided into an output pulse signal A having a large voltage value [see FIG. 2 (b)] and an output pulse signal having a small voltage value [see FIG. 2 (c)]. Sample each. As a result, if the separation distance of the magnetic sensor 24 from the permanent magnet 22 is held at the set value,
The number of pulses per unit time is equal to that of the divided output pulse signal A. The number of these pulses can be easily counted by a pulse counter.

Therefore, for example, when the front bearing is worn in the thrust direction and the rotor shaft 10 is displaced, the distance between the permanent magnet 22 and the magnetic sensor 24 increases, and the magnetic sensor 24
The voltage level of the output pulse signal obtained in step 1 is relatively lower than the threshold voltage Vs level [Fig. 2
(a)]. As a result, since the number of pulses of the output pulse signal is larger than that of the output pulse signal A which is divided by comparing the voltage levels [Figs. 2 (b) and (c)], the number of pulses per unit time is changed. The amount of wear of the front bearing in the thrust direction can be detected.

Further, when the rear bearing is worn in the thrust direction and the rotor shaft 10 is displaced, the permanent magnet 22 and the magnetic sensor 24 are moved.
The distance between and becomes smaller, and the voltage level of the output pulse signal obtained by the magnetic sensor 24 becomes relatively higher than the threshold voltage Vs level [FIG. 2 (a)]. As a result, the number of pulses of the output pulse signal A increases in contrast to the output pulse signal A divided by comparing the voltage levels [FIGS. 2 (b) and (c)]. The amount of wear in the thrust direction of the rear bearing can be detected by the number of pulses per hour.

FIG. 3 shows another embodiment of the bearing monitor system according to the present invention, in which only the wear amount of the bearing in the radial direction is detected. That is, the third
In the figure, the end nut 18 attached to the end portion of the rotor shaft 10 is set to have a cylindrical hole portion 26 which is concentric with the shaft, and the tip end portion of the sensor holding body 20 is arranged in the cylindrical hole portion 26 at a predetermined interval. Insert and place them separately. Therefore, in this case, with respect to the end nut 18 and the sensor holding body 20,
The permanent magnet 22 and the magnetic sensor 24 are arranged to face each other in the radial direction. With this configuration, the wear amount of the bearing in the radial direction can be detected by the change in the voltage level of the output pulse signal detected by the magnetic sensor 24. In this case, it is possible to determine the wear position in the radial direction of the bearing by setting the threshold voltage Vs, as in the above-described embodiment.

FIG. 4 is still another embodiment of the bearing monitor system according to the present invention, and shows a case where both the wear amount in the thrust direction and the wear amount in the radial direction of the bearing are simultaneously detected. That is, the present embodiment is a combination of the embodiments shown in FIGS. 1 and 3, and the permanent magnet 22 embedded in the end portion of the end nut 18 with respect to the radial direction of the sensor holding body 20 and the permanent magnet 22. Magnetic sensors 24a and 24b are provided at axial positions. Here, the signals detected by the magnetic sensors in the radial direction and the thrust direction are separately detected using the sawtooth wave shown in FIG. 2 to detect the number of pulses per unit time,
The amount of wear is detected in the same manner as described in the embodiment of FIGS. 1 and 3.

FIG. 5 shows an application example of the bearing monitor system according to the present invention, in which only the wear amount in the thrust direction is electrically detected, and the wear in the radial direction is detected by conventional mechanical means. That is, in this embodiment, similarly to the embodiment shown in FIG. 3, the end nut 18 having the cylindrical hole portion 26 is used, and the tip end portion of the sensor holding body 20 is arranged in the cylindrical hole portion 26 at a predetermined interval. Insert and place them separately. In this case, the permanent magnet 22 is provided at the opening end portion of the end nut 18 so as to project slightly inward, and the tip end portion of the sensor holding body 20 also bulges slightly outward so that the permanent magnet 22 and the shaft are provided therein. Magnetic sensors 24 are provided so as to face each other. Further, in this case, the sensor holder 20 has a hermetically sealed tube structure and is configured as a detector of a conventional bearing monitor by a mechanical means as a sensing part which ruptures the tip thereof due to wear. By configuring in this way, with respect to wear in the thrust direction of the bearing,
The amount of wear can be detected by the bearing monitor system of the present invention described above, and the wear limit of the bearing can be detected by conventional mechanical means for radial wear of the bearing.

〔The invention's effect〕

As is apparent from the above-mentioned embodiments, according to the present invention,
A magnetism generating element such as a permanent magnet is provided at the end of the rotor shaft supported by a bearing, and a sensor holder provided with a magnetic sensor facing the magnetism generating element is spaced from the rotor shaft end by a predetermined distance. With the fixed arrangement, the magnetic sensor generates a pulse signal with a voltage level proportional to the distance from the magnetism generating element as the rotor shaft rotates, so this pulse signal is compared with a predetermined threshold voltage to generate a pulse signal. By dividing and sampling the signal, it is possible to easily detect the wear amount of the bearing in the thrust direction, which has been conventionally difficult.

Further, according to the bearing monitor system of the present invention, not only the amount of wear in the thrust direction of the bearing, but also the amount of wear in the radial direction of the bearing can be detected by changing the arrangement of the magnetic generation element and the magnetic sensor. Further, according to the bearing monitor system of the present invention, it is possible to use the conventional bearing wear detector by mechanical means to detect the amount of wear particularly in the thrust direction and improve the function and performance of the bearing monitor system. You can

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part of a rotor shaft end portion of a canned motor showing an embodiment of a bearing monitor system according to the present invention, and FIGS. 2 (a), (b) and (c) are shown in FIG. FIG. 3 is a characteristic waveform diagram showing the correlation between the sensor output pulse signal and the amount of wear of the bearing in the bearing monitor system shown in FIG. 3, and FIG. 3 shows another embodiment of the bearing monitor system according to the present invention at the rotor shaft end of the canned motor. Cross-sectional side view of essential parts,
FIG. 4 is a sectional side view of a main part of a rotor shaft end portion of a canned motor showing still another embodiment of the bearing monitor system according to the present invention, and FIG. 5 is a canned view showing an application example of the bearing monitor system according to the present invention. It is a principal part cross-sectional side view of the rotor shaft end part of a motor. 10 ... Rotor shaft, 12 ... Thrust washer 14 ... Bearing, 16 ... Bearing housing 18 ... End nut, 20 ... Sensor holder 22 ... Permanent magnet, 24 ... Magnetic sensor 26 ... Cylindrical hole

Claims (2)

[Claims] 1. A sensor holder provided with a magnetic field generating element at one end of a rotary shaft supported by a bearing, and a magnetic sensor provided with a magnetic sensor in the axial direction and / or the radial direction of the rotary shaft which is displaced by wear of the bearing. They are fixedly arranged apart from each other, and a pulse signal having a voltage level proportional to the distance from the rotating shaft is output by a magnetic sensor as the rotating shaft rotates, and this voltage level is compared with a reference voltage level to determine the thrust direction of the bearing. And / or a signal of a change in the axial direction and / or the radial direction of the magnetic field generated by one magnetic generating element for the wear amount in the radial direction is independently provided by the magnetic sensors provided in the axial direction and / or the radial direction. Bearing monitoring system characterized by detecting. 2. The bearing monitor system according to claim 1, wherein the voltage pulse signal detected by the magnetic sensor is superposed on a reference voltage level of a sawtooth wave having a predetermined cycle which defines the limit of wear of the bearing. The bearing monitor is configured to detect the wear position of the bearing by dividing the pulse signal according to the reference voltage level and counting the number of pulses per unit time of the divided pulse signal. system.