JP2509600Y2 - Bearing wear monitor - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear monitor for plain bearings, especially sealed plain bearings in canned motor pumps and the like.

[0002]

2. Description of the Related Art Generally, in a canned motor pump, the radial and thrust loads of a rotating portion during operation are all applied to a slide bearing that supports a rotating shaft of the rotating portion. However, the bearing is placed in the handling liquid,
Being hermetically sealed, this bearing is generally equipped with a special bearing wear monitor to monitor its wear.

By the way, the conventional bearing wear monitor (mechanical type or electric type) is such that, first of all, a mechanical type is provided with a detecting portion having a hollow detecting portion at the end of the rotary shaft, and the hollow detecting portion is a bearing. Is damaged by radial displacement of the rotary shaft when it is worn in the radial direction, and broken by axial displacement when it is worn in the thrust direction, so as to monitor the limit wear in the radial and thrust directions. In the electric type, a magnetic flux detecting 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, thereby monitoring the degree of wear in the radial direction. Is configured.

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 has previously developed and proposed 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. (Practical application Hei 3-626
No. 9).

This newly proposed bearing wear monitor corresponds to a truncated cone-shaped detecting portion which shares a central axis with respect to the rotating shaft supported by the slide bearing, and the detecting portion. A non-contact displacement sensor that detects the distance from the detection unit is provided. Therefore,
According to this technique, when the bearing wears (in this case, the wear is radial or thrust),
The distance from the detection part detected by the sensor changes in proportion to the degree of wear because the detection part is trapezoidal.
It is possible to monitor the course of wear in both radial and thrust directions.

[0007]

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 and reliable in the thrust direction. Although 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 at the time of 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 rotary shaft whirls (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.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bearing wear monitor capable of monitoring the wear of a bearing in both radial and thrust directions in a transitive, reliable and sufficient manner.

[0011]

In order to achieve the above object, a bearing wear monitor according to the present invention includes a magnetic field sharing a central axis with respect to a rotary shaft supported by a slide bearing. a detection unit, and the magnetic sensor pairs for detecting the intensity of the magnetic field from the disposed centerline axis of symmetry relates rotary shaft wherein the detection portion is provided.

Further , the detection unit is a permanent magnet and / or
Alternatively, it is formed from a permanent magnet and a ferromagnetic material. This inspection
It is common that the strength of the magnetic field at the exit is constant in the radial direction of the rotation axis.
Monotonic to one and / or both sides in the direction of the central axis
The detector is configured to change.

In this case, each pair of sensors has its own
Addition and / or subtraction of the detection output value of the sensor
Can be configured as follows.

[0014]

When the bearing wears, whether the wear is radial or thrust, the strength of the magnetic field from the detectors detected by each pair of sensors changes in proportion to the degree of wear. Therefore, the wear profile 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 determination of wear, so that the rotation shaft temporarily rotates eccentrically 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]

Embodiments of the bearing wear monitor according to the present invention will now be described 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 space defined by both ends 16 and 18 of the motor unit 12 and a can 20. Is disposed inside the sleeve 22, and the both ends of the sleeve 22 are
Rear and front slide bearings 26, 2 respectively via 24
It is configured to be supported by eight.

However, in the bearing wear monitor of the present invention, the rotating shaft 1 supported by the both bearings 26, 28 is supported.
4, the magnetic detection parts 34 and 36 are arranged via the frames 30 and 32 so as to share the central axis with respect to the rotating shaft 14, and the magnetic detecting parts 34 and 36 are arranged outside the can 20 symmetrically about the central axis with respect to the rotating shaft 14. Monitor devices 42 and 44 are provided which are composed of a plurality of pairs of magnetic sensors 38 and 40 for detecting the strength of the magnetic field from the detection units 34 and 36.

Here, in the monitor devices 42 and 44, the detecting portions 34 and 36 are formed in a truncated cone shape, as is apparent from the enlarged views of FIGS. 2 (a) and 2 (b). The magnetic strength from the detectors 34, 36 detected by the sensors 38, 40 [see FIG. 3 (a)] is constant in the radial direction of the rotary shaft 14, but in the central axis direction, that is, in FIG. As shown in (a) and (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) may be the integral permanent magnet 30a [FIG. 3 (b)] or the permanent magnet piece 3
Forming a complex of 0b and ferromagnetic 30 c [FIG 3 (c)], the sensor 38 (40) is formed from a Hall element or a coil or the like, disposed outside of the can 20. In addition, as shown in FIG. 4, the detection unit is a symmetrical truncated cone 30 '.
It is also possible to form the unitary permanent magnet 30a 'or a composite body of the permanent magnet piece 30b' and the ferromagnetic body 30c '. Then, in this case, the detection unit 3
The magnetic intensity detected at 0 (32) symmetrically and monotonically changes 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 pair detected is centered on the reference value Pn with respect to the radial displacement t, Maximum value Pmax to minimum value Pmin
Although it is monotonically changing up to, it is respectively calculated as shown in FIG. 6 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 the above structure will be described. First, as shown in FIG. 7, when the sliding bearing 26 wears and the rotary shaft 14 whirls and rotates, 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 the reference value (smooth line) R when not worn.
The offset waveforms R1 and R2 corresponding to the wear amount are converted from 0. On the other hand, the addition output 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 a constant value R1, R corresponding to the wear amount from the reference value (smooth line) R0.
2, while the addition output Q (FIG. 11) maintains the reference value (zero) Q0 at Q1 and Q2. When the wear is in both radial and thrust directions, the output (the subtraction output R and the 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, the sliding bearing 26
When the rotating shaft 14 is eccentrically rotated due to wear, the output from the monitor device 42 in this case is the subtraction output R (see FIG.
3) and the added output Q (FIG. 14) are output R1, R2 and Q1, which are constant values (not AC waveforms) corresponding to the wear amount from the reference values (smooth lines) R0 and Q0, respectively.
It is converted into Q2 and Q1 ', 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 calculated from the two pairs of addition outputs R and R '. To be measured. The direction of wear in the thrust direction is determined by which of the slide bearings 26, 28 is worn in FIG.
It can be easily determined by comparing 2, 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 reliably and sufficiently monitored regardless of whirling or eccentric rotation of the rotating shaft. You can Moreover,
The 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 when the bearing should be replaced, and thus the reliability of the device can be significantly improved.

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]

As described above, the bearing wear monitor according to the present invention is provided with respect to the rotary shaft supported by the slide bearing.
By providing a magnetic sensor pairs for detecting the intensity of the magnetic field from the disposed centered axis symmetrical magnetic detector unit to share the center axis relates the rotation axis and relates to the rotary shaft the detector, a radial bearing And transient wear in both thrust directions can be reliably and sufficiently monitored regardless of whirling of the rotating shaft or eccentric rotation, and the bearing replacement timing can be clearly determined and the reliability of the device can be improved. Can be greatly improved. Moreover, according to the present invention, the whirling or eccentric rotation of the rotary shaft 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 (1)

(57) [Scope of utility model registration request] 1. A rotary shaft supported by a slide bearing,
Wherein the magnetic detection unit that shares the central axis relates the rotation axis, wherein arranged in the central axis symmetrically about the rotation axis is provided and a magnetic sensor pairs for detecting the intensity of the magnetic field from the detection unit, the detection unit, Permanent magnet and / or permanent magnet and strong
The magnetic field strength of the detection unit is the radius of the rotation axis.
Direction is constant and one side and / or also in the direction of the central axis
A bearing wear monitor characterized by being configured to change monotonically toward both sides .