JPH0612823U - Bearing wear monitor - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a bearing wear monitor capable of reliably and sufficiently monitoring the transitional wear of a bearing in both radial and thrust directions irrespective of whirling of the rotating shaft or eccentric rotation. [Structure] With respect to a rotating shaft supported by a bearing, a magnetic detecting unit arranged so as to share the central axis thereof, whose magnetic strength monotonously changes in the central axis direction, and the detecting unit arranged symmetrically with respect to the central axis line. A plurality of pairs of magnetic sensors for detecting the strength of the magnetic field from the sensor are provided, and the addition output Q and the subtraction output R are calculated from the outputs from the respective sensors of each pair. As a result, it is possible to transitively monitor all wear of the bearing from the outputs Q and R.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wear monitor for a plain bearing, particularly a sealed plain bearing in a canned motor pump or the like.

[0002]

[Prior art]

 Generally, in a canned motor pump, the radial and thrust loads of the rotating part during operation are all applied to a slide bearing that supports the rotating shaft of the rotating part. However, since the bearing is placed and sealed in the liquid to be handled, a special bearing wear monitor for monitoring the wear of the bearing is generally installed.

By the way, in the conventional bearing wear monitor (mechanical type or electric type), first of all, the mechanical type is provided with a detection unit having a hollow sensing unit at the end of the rotating shaft, and the hollow sensing unit is When is worn in the radial direction, it is destroyed by radial displacement of the rotating shaft, and when worn in the thrust direction, it is destroyed by axial displacement, so that the critical wear in the radial and thrust directions is monitored. In the electric type, a magnetic flux detection coil is provided in the stator, and the electromotive force in this coil increases due to radial displacement of the rotating shaft when the bearing wears, so that the wear degree in the radial direction is monitored. Is configured to.

That is, in the conventional bearing wear monitor, the mechanical type can first monitor the limit wear in both radial and thrust directions, but the transition to the limit wear (residual life) is monitored. I couldn't do it. On the other hand, the electric type can monitor the wear degree (wear change) in the radial direction, but cannot monitor anything in the thrust direction.

Therefore, the present applicant previously developed a new technique capable of solving the above-mentioned difficulties, that is, a technique capable of transitively monitoring wear in both radial and thrust directions, We made a proposal (Practical application No. 3-6269).

This newly proposed bearing wear monitor has a truncated cone-shaped detection unit that shares a central axis with respect to a rotation shaft supported by a slide bearing, and a pair of detection units. It is configured by providing a non-contact displacement sensor that detects the distance from the detection unit. Therefore, according to this technology, if the bearing wears (in this case, the wear is radial or thrust), the distance detected by the sensor from the detector is trapezoidal. Since it changes in proportion to the degree of wear, it is possible to monitor the change in wear in both radial and thrust directions.

[0007]

[Problems to be solved by the device]

 However, it has been found that even the above-mentioned proposed technique (hereinafter referred to as the conventional technique) still has a drawback to be improved.

That is, in the above-mentioned prior art, the wear of the bearing can be monitored by the detection distance that changes according to the degree of wear, but the change in the detection distance is constant with respect to the thrust direction. Although certainly achieved, it was not always possible in the radial direction.

Therefore, in the prior art, there has been a problem that the change in wear in the radial direction is often not reliably and sufficiently monitored. Incidentally, this difficulty was basically due to the fact that the radial displacement of the rotating shaft during radial wear of the bearing could not be constantly and reliably achieved corresponding to the wear. That is, when the bearing is worn in the radial direction, the rotating shaft swirls and rotates (see FIG. 7 of the present invention described in detail below) or eccentrically rotates (see FIG. 12). However, in this case, the change in the detection distance was due to the fact that the change in the detection distance was constantly and reliably achieved in the former case, but could not be achieved in the latter case.

Therefore, an object of the present invention is to provide a bearing wear monitor capable of steadily and reliably monitoring wear of the bearing in both radial and thrust directions.

[0011]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a bearing wear monitor according to the present invention comprises a magnetic detection unit sharing a central axis with respect to a rotary shaft supported by a plain bearing, and a central axis line with respect to the rotary shaft. And a plurality of pairs of magnetic sensors that are arranged symmetrically and that detect the strength of the magnetic field from the detection unit.

In this case, each pair of sensors can be configured to add and / or subtract the detection output values of its respective sensor.

Further, the detection unit is formed of a permanent magnet and / or a permanent magnet and a ferromagnetic material, and the magnetic field strength of the detection unit is constant in the radial direction of the rotation axis and one side in the central axis direction. And / or can be configured to be monotonic towards both sides.

[0014]

[Action]

 When the bearing wears, whether the wear is radial or thrust, the strength of the magnetic field from the detector detected by each pair of sensors changes in proportion to the degree of wear. Therefore, the change of wear can be monitored in both radial and thrust directions. Moreover, in this case, in particular, the detection output values of the respective sensors of each set are added and / or subtracted and then used for the judgment of wear, so that the rotary shaft is eccentrically rotated during wear in the radial direction. Even in such a case, it becomes possible to reliably and sufficiently monitor the transition of the degree of wear.

[0015]

Embodiment An embodiment of the bearing wear monitor according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a canned motor pump to which the bearing wear monitor of the present invention is applied. Therefore, in FIG. 1, the canned motor pump is composed of a pump unit 10 and a motor unit 12, and a rotary shaft 14 of the pump is a liquid-tight seal defined by both ends 16 and 18 of the motor unit 12 and a can 20. It is arranged in a space, and its both ends are supported by rear and front slide bearings 26 and 28 via sleeves 22 and 24, respectively.

However, in the bearing wear monitor of the present invention, with respect to the rotary shaft 14 supported by the bearings 26 and 28, the frames 30 and 32 are provided so as to share the central axis with respect to the rotary shaft 14. Magnetic detection units 34 and 36 arranged in parallel with each other, and a plurality of pairs of magnetic sensors 38 arranged on the outside of the can 20 symmetrically with respect to the rotating shaft 14 and detecting the magnetic field intensity from the detection units 34 and 36. , 40 are provided.

Here, in the monitor devices 42 and 44, the detection portions 34 and 36 are formed in a truncated cone shape, as will be apparent from FIGS. 2A and 2B which are enlarged. The magnetic intensity (see FIG. 3 (a)) from the detectors 34, 36 detected by the sensors 38, 40 is constant in the radial direction of the rotation shaft 14, but in the central axis direction, that is, in the figure. As shown in FIGS. 2 (a) and 2 (b), when the rotary shaft 14 is displaced in the axial direction t, the rotary shaft 14 monotonously changes toward one side. The detection unit 30 (32) is formed by a single permanent magnet 30a [FIG. 3 (b)] or a composite body of the permanent magnet piece 30b and the ferromagnetic body 30 [FIG. 38 (40) is formed of a Hall element or a coil and is arranged outside the can 20. As shown in FIG. 4, the detecting portion is a symmetric truncated cone 30 'and is formed of an integral permanent magnet 30a' or a composite of permanent magnet pieces 30b 'and a ferromagnetic body 30c'. You can In this case, the magnetic intensity detected by the detection unit 30 (32) changes symmetrically and monotonically toward both sides of the central axis.

In the present invention, as shown in FIG. 5, the output P (Pa, Pb) from each sensor 38, 40 of each detected pair is centered on the reference value P n with respect to the radial displacement t. Then, although it changes monotonically from the maximum value Pmax to the minimum value Pmin, as shown in FIG. 6, they are respectively calculated and set to the addition output Q and the subtraction output R.

Next, the operation of the bearing wear monitor of the present invention having such a configuration will be described. First, as shown in FIG. 7, when the plain bearing 26 wears and the rotary shaft 14 swings around, the output from the monitor device 42 shows that when the wear is not in the thrust direction but in the radial direction, The subtraction output R (FIG. 8) is converted from the reference value (smooth line) R0 when there is no wear into the offset waveforms R1 and R2 corresponding to the wear amount. On the other hand, the additive calculation force Q (FIG. 9) is converted from the reference value (zero) Q0 into AC waveforms Q1 and Q2 centered on zero. When the wear is not in the radial direction but in the thrust direction, the subtraction output R (Fig. 10) is converted from the reference value (smooth line) R0 to the constant values R1 and R2 corresponding to the wear amount, and the addition is performed. The output Q (FIG. 11) maintains the reference value (zero) Q 0 and keeps Q1 and Q2. When the wear is in both the radial and thrust directions, the output (subtraction output R and addition output Q) from the monitor device 42 becomes a composite waveform of the respective outputs described above. In this case, since the addition output indicates wear in the radial direction, the absolute value of the addition output is multiplied by a constant, and this value is subtracted from the value of the subtraction output to determine the function of wear in the thrust direction. It can be easily requested.

Next, as shown in FIG. 12, when the sliding bearing 26 wears and the rotating shaft 14 rotates eccentrically, in this case, the output from the monitor device 42 is the subtracted output R (FIG. 13). In addition, the added outputs Q (FIG. 14) are output from the reference values (smooth lines) R0 and Q0, respectively, which are constant values (not AC waveforms) corresponding to the wear amount R1, R2 and Q1, Q2 and Q1 ', Converted to Q2 '. Therefore, it is clearly distinguished from the case of whirling rotation described above, and in this case, the wear amount in the thrust direction is measured from the subtraction output R, and the wear amount in the radial direction is obtained from the two pairs of addition outputs R and R '. Calculated and measured. The direction of wear in the thrust direction is determined by which of the slide bearings 26, 28 is worn in FIG. 1, and can be easily determined by comparing both monitor devices 42, 44.

As described above, according to the bearing wear monitor of the present invention, the transitional wear of the bearing in both radial and thrust directions can be accurately and sufficiently monitored regardless of whirling or eccentric rotation of the rotating shaft. can do. Moreover, whirling or eccentric rotation of the rotating shaft can be clearly determined, and the thrust direction can be monitored together. Therefore, it is possible to clearly determine the bearing replacement time, which can greatly improve the reliability of the device.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and many improvements and modifications can be made without departing from the spirit thereof.

[0024]

[Effect of device]

 As described above, the bearing wear monitor according to the present invention is arranged symmetrically with respect to the rotating shaft supported by the slide bearing, with respect to the rotating shaft and the magnetic detection unit sharing the central axis with respect to the rotating shaft. By providing a plurality of pairs of magnetic sensors that detect the strength of the magnetic field from the detection section, the transitional wear of the bearing in both radial and thrust directions can be prevented regardless of whirling of the rotating shaft or eccentric rotation. Therefore, it is possible to reliably and sufficiently monitor the bearing, the bearing replacement timing can be clearly determined, and the reliability of the device can be significantly improved. Moreover, according to the present invention, the whirling of the rotary shaft or the eccentric rotation can be clearly determined, and the thrust direction can be monitored together.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment in which a bearing wear monitor according to the present invention is applied to a canned motor pump.

FIG. 2 is a partially enlarged view of the monitor device shown in FIG.
Shows the state when both front and rear bearings were not worn, and (b) shows the state when the front bearing in both bearings was worn.

3 is an enlarged explanatory view of the magnetic detector shown in FIG. 2, (a)
Indicates the characteristics of the magnetic strength detected by the magnetic sensor,
(B) and (c) show examples of magnetic detector configurations.

FIG. 4 is an enlarged explanatory view corresponding to FIG. 3 showing another embodiment of the magnetic detector, (a) showing characteristics of magnetic strength detected by the magnetic sensor, and (b) and (c). Shows examples of the configurations of the magnetic detectors.

FIG. 5 is a graph showing an output P of the magnetic sensor according to the radial displacement t of the magnetic detector.

FIG. 6 is a graph showing the characteristics of the addition output Q and the subtraction output R of two magnetic sensors forming a pair with the rotation period T of the rotating shaft.

FIG. 7 is a cross-sectional view of essential parts showing a whirling and rotating state of a rotating shaft.

FIG. 8 is a graph showing a characteristic of a subtraction output R during whirling rotation of a rotating shaft due to radial wear of a bearing.

FIG. 9 is a graph showing the characteristics of the added output Q when the rotating shaft whirls and rotates due to radial wear of the bearing.

FIG. 10 is a graph showing the characteristic of the subtraction output R when the rotating shaft whirls and rotates due to wear of the bearing in the thrust direction.

FIG. 11 is a graph showing the characteristics of the added output Q when the rotating shaft whirls due to wear in the thrust direction of the bearing.

FIG. 12 is a cross-sectional view of essential parts showing an eccentric rotation state of a rotating shaft.

FIG. 13 is a graph showing a characteristic of a subtraction output R when the rotating shaft is eccentrically rotated due to bearing wear.

FIG. 14 is a graph showing a characteristic of an added output Q when the rotating shaft is eccentrically rotated due to bearing wear.

[Explanation of symbols]

10 pump part 12 motor part 14 rotary shaft 16,18 end part 20 can 22,24 sleeve 26,28 slide bearing 30,30 ', 3
2 Frames 30a, 30a 'Integrated permanent magnets 30b, 30b'
Permanent magnet pieces 30c, 30c 'Ferromagnetic material 34, 36 Magnetic detector 38, 40 Magnetic sensor 42, 44 Monitor device

Claims (3)

[Scope of utility model registration request] 1. A rotary shaft supported by a slide bearing,
A bearing comprising: a magnetic detection unit that shares a central axis with respect to the rotation axis; and a plurality of pairs of magnetic sensors that are arranged symmetrically about the central axis with respect to the rotation axis and that detect the strength of the magnetic field from the detection unit. Wear monitor. 2. The bearing wear monitor according to claim 1, wherein each pair of sensors is formed by adding and / or subtracting the detection output value of each sensor. 3. The detector comprises a permanent magnet and / or a permanent magnet and a ferromagnetic material, and the strength of the magnetic field of the detector is constant in the radial direction of the rotation axis and one and / or both sides in the central axis direction. The bearing wear monitor according to claim 1, wherein the bearing wear monitor is configured so as to change monotonically.