JPH0425614Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to an improvement of a shaft system monitoring device for a closed type pump, and is suitable for detecting wear of a bushing of a pump for low-temperature liquefied gas, etc.

[Conventional technology]

Sealed pumps, such as submersible motor pumps, have a motor and pump housed in a sealed container.
It is used for various purposes. For example, sealed pumps are also used to pump low-temperature liquefied gases such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG).

As shown in FIG. 3, the schematic structure of such a closed type pump is that a pump shaft 4 of a pump 3 is integrally constructed or connected to the lower end of a motor shaft 2 of a motor 1 having a liquid-resistant structure, and rotates integrally with the lower end of the motor shaft 2. It has become like this,
These motor 1 and pump 3 are housed in an airtight container 5, and liquid is sucked in from a suction port 6 formed on the side of the airtight container 5, enters the pump 3 from an inducer 7, and is heated by a three-stage impeller 8. The compressed air passes between the rotor 9 and stator 10 of the motor 1 and is discharged from an upper discharge port (not shown).

In the shaft system of this sealed pump, a motor shaft 2 has a ball bearing 1 attached to a motor housing 11.
The pump shaft 4 is rotatably supported by a bush 15 attached to a bush support 14 integral with the pump housing 13.

[Problem that the invention attempts to solve]

In such a closed type pump, there is a problem in that when the ball bearing 12 and the bush 15 wear out during operation, the shaft system vibrates, causing damage to the shaft system and the like.

Therefore, countermeasures such as increasing the number of maintenance inspections are required, but open inspections take a long time due to the closed structure, and especially for pumps used for low-temperature liquids such as LNG, which are flammable liquids. It is even more complicated as it requires purging and cool-down (pre-cooling) before operation.

Therefore, a piezoelectric acceleration sensor is attached to the motor housing 11 or the pump housing 13 to monitor the vibration of the shaft system, but even if the displacement is determined by integrating the detected vibration acceleration, it is not always possible to It does not correspond to the amount of wear and tear, and it has not become a sufficient monitoring method to replace open inspection.

This idea was made in view of the prior art, and it is possible to directly detect the amount of wear on bushings, etc., and also to monitor abnormalities in the shaft system by detecting the shaft load that causes wear. The present invention aims to provide a shaft system monitoring device for a sealed pump.

[Means for solving problems]

In order to solve the above-mentioned problems, the shaft system monitoring device for a sealed pump according to the present invention provides a motor for monitoring the pump shaft of a sealed pump in which the motor and the pump are connected via the pump shaft and housed in a sealed container. A pump shaft bushing support that rotatably supports the pump shaft on the opposite side is placed perpendicular to the length direction of the pump shaft and facing the pump shaft to detect displacement in the direction perpendicular to the pump shaft due to wear of the bushing. At the same time, the pump shaft bush support is formed into a wheel shape connected by ribs, and the opposite longitudinal sides of at least one rib are provided with a non-contact type displacement sensor that can be applied to the rib. This is characterized by a load detection sensor that detects the load in the bending direction.

[Effect]

A non-contact displacement sensor is installed inside a sealed pump so as to face the surface of the pump shaft in a direction perpendicular to the axial direction of the pump shaft to directly monitor the amount of wear on the bushing from the amount of movement of the pump shaft in the direction perpendicular to the axis. At the same time, the shaft load that causes wear is removed by the load detection sensors such as strain gauges attached to both sides of the ribs of the wheel-shaped bushing support to which the bushing that rotatably supports the pump shaft is attached. By detecting and monitoring loads in the direction and bending direction, damage to the shaft system can be prevented and overhaul inspections can be carried out at the optimal time.

〔Example〕

An embodiment of this invention will be described in detail below with reference to the drawings.

1 and 2 are a partially enlarged sectional view and a partially planar sectional view of an embodiment of the shaft system monitoring device for a sealed pump according to the present invention.

Shaft system monitoring device 20 for a sealed pump of this invention
is composed of a non-contact displacement sensor 21 for detecting the amount of wear on the bush 15, a load detection sensor 22 for detecting the shaft load, and an arithmetic processor 23 for processing these detected values. ing.

As the non-contact displacement sensor 21, for example, a sensor that detects displacement using eddy current is used,
A bracket 24 is attached to the lower surface of the bush support 14 to which the bush 15 that supports the pump shaft 4 is attached.
It is mounted so as to face the pump shaft 4 with a slight gap therebetween. That is, the bush support 14 to which the non-contact displacement sensor 21 is attached via the bracket 24 is connected to the pump shaft 4.
This is to support a bushing 15 that rotatably supports this pump shaft 4 on the side opposite to the side to which the motor 1 is connected, and as shown in FIG. It has a wheel-like configuration with an annular pump shaft support section and three radial ribs 14a connecting this to the pump housing 13. Rib 14 of this bushing support 14
A bracket 24 is attached to the lower surface of the pump shaft 4, and a non-contact displacement sensor 21 is arranged in the radial direction (in the direction of the rib 14a) perpendicular to the length direction of the pump shaft 4, with a slight gap between the bracket 24 and the surface of the pump shaft 4. They are installed facing each other. Further, as the load detection sensor 22, for example, a strain gauge is used, and is attached to both sides of the rib 14a of the bush support 14, which is arranged in a plane perpendicular to the axis of the pump shaft 4. The load in the expansion/contraction direction and the bending direction of the rib 14a is detected from the amount of strain.

The lead wires of the non-contact displacement sensor 21 and the load detection sensor 22 pass through the pump housing 13 and also through the closed container 5 to be led out and connected to the arithmetic processor 23.

According to the shaft system monitoring device 20 for a sealed pump configured as described above, the distance between the pump shaft 4 and the non-contact displacement sensor 21 can always be detected even when the pump is operated in a sealed state, and the distance between the pump shaft 4 and the non-contact displacement sensor 21 can be detected based on this detected value. Therefore, the amount of wear of the bush 15 supporting the pump shaft 4 in the direction orthogonal to the pump shaft 4 can be known, and the closed container 5 can be monitored without opening it.

In addition, the load detection sensors 22 attached to both sides of the ribs 14a of the bush support 14 can directly measure the loads applied to the bush 15 in the stretching and bending directions, which is effective in analyzing the causes of wear on the bush 15. By comparing the design loads in the expansion/contraction direction and the bending direction, it is possible to determine whether an open inspection is necessary.

Therefore, the bush 15 supporting the pump shaft 4
Accidents such as the inducer 7 interfering with the pump housing 13 and being damaged due to wear can be prevented, and the number of overhaul inspections can be significantly reduced.

In the above embodiment, an eddy current type displacement sensor is used as a non-contact displacement sensor.
This is not limited to this, but any other type of device may be used as long as it can detect the load applied to the bush in the expansion/contraction direction and the bending direction in the direction perpendicular to the pump axis, and can detect displacement without being affected by the liquid flowing inside the pump. That's fine.

Furthermore, the load detection sensor is not limited to the strain gauge, but may be any other sensor.

Furthermore, although the installation position of these sensors was set to monitor the bushing farthest from the motor, other bushings, ball bearings, etc. may be targeted, or they may be installed at a plurality of locations.

[Effect of idea]

As specifically explained above with one embodiment, according to this invention, a non-contact displacement sensor is installed inside a closed pump so as to face the surface of the pump shaft in a direction perpendicular to the axial direction of the pump shaft. Since the load detection sensors are installed on both sides of the ribs of the wheel-shaped bushing support to which the bushing that rotatably supports the pump shaft is attached, the amount of movement of the bushing in the direction perpendicular to the pump shaft can be measured. In addition to being able to directly monitor the amount of wear,
The axial load applied to the bushing, which causes wear, can be directly measured as a load in the stretching and bending directions using a load detection sensor such as a strain gauge. The status of the shaft can be known with certainty.

Furthermore, the number of times the sealed container is opened can be significantly reduced, and maintenance and inspection can be prevented from being delayed and causing major damage.

Furthermore, since the load applied to the bush in the expansion/contraction direction and the bending direction in the direction perpendicular to the pump axis is measured, it is easy to analyze the cause of wear and take appropriate measures.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the system for monitoring the shaft system of a closed pump according to this invention. FIG. 2 is a vertical cross-sectional view of an example of an application target. 4...Pump, 13...Pump housing, 1
4...butsuyu support, 15...butsuyuu, 2
0... Shaft system monitoring device for sealed pump, 21... Non-contact displacement sensor, 22... Load detection sensor,
23... Arithmetic processor, 24... Bracket.

Claims (1)

[Scope of utility model registration request] A pump shaft bushing support that rotatably supports the pump shaft on a side opposite to the electric motor of a closed type pump in which an electric motor and a pump are connected via a pump shaft and housed in a closed container. ,
A non-contact displacement sensor is installed to face the pump shaft perpendicularly to the length direction of the pump shaft and can detect displacement in the direction perpendicular to the pump shaft due to wear of the bushing, and the pump shaft bush support is connected with a rib. a closed type, characterized in that the rib is formed in the shape of a wheel, and load detection sensors for detecting loads in the stretching and bending directions applied to the rib are attached to both opposing sides in the longitudinal direction of at least one rib; Pump shaft system monitoring device.