JPH03124999A - Lubricalting water feeding method to bearing of induction motor-driven pump - Google Patents

Abstract

PURPOSE:To surely feed the lubricating water to a bearing and perform control by feeding the lubricating water to the bearing of a pump main spindle when the detected phase difference of a power circuit is larger than the intermediate value between aerial and pumping operations, and stopping the lubricating water when it is smaller. CONSTITUTION:A phase detector 10 detecting the phase difference between the voltage and current and outputting a detected signal corresponding to it is connected to the power circuit IMC of an induction motor IM, and the detected signal outputted from it is fed to a water feed control means 11. The water feed control means 11 compares the detected signal with the preset value which is the intermediate value of the phase difference between aerial and pumping operations, it outputs an opening control signal to the valve 9C of a lubricating water feed system 9 when the detected signal is larger than the preset value based on the compared result, and it outputs a closing control signal when the detected signal is smaller. When the valve 9C is opened by the control signal, the lubricating water is fed to bearings 5 and 8 of a pump main spindle 2 from the lubricating water feed system 9 to lubricate and cool the bearings 5 and 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for supplying lubricating water to the bearings of a pump whose drive source is an induction motor.

[Prior Art] For example, ceramic bearings are used as bearings for indoor shaft pumps, which are lubricated and cooled by self-pumped water and can continue stable operation.

This type of bearing operates dry for a very short period of time immediately after the pump is started, and after this short period of time, it is immediately lubricated and cooled by self-pumped water and begins stable operation. That is, in ceramic bearings, dry operation is limited to a short time.

On the other hand, with the rapid progress of urbanization, the amount of rainwater flowing into drainage pump stations installed in waterways is rapidly increasing in volume. In such a situation, even if the water level in the water intake well at the drainage pump station falls below the pumping cutoff water level of the indoor shaft pump, dry operation is continued, and advance standby operation or air control operation that precedes the pump operation status is recommended. We are responding by doing this.

The indoor shaft pump used in the advance standby operation and the air management operation continues to operate dry for a long time, and during this period, no lubricating water is supplied to the bearings. Therefore, it has not been possible to use a ceramic bearing, which limits the dry operation time to a short time, in a chamber shaft pump that performs advance standby operation or air control operation.

One possible solution to this problem is to supply lubricating water to the bearing from the outside, but in this case, it is not possible to continue supplying lubricating water from the outside even during pumping operation. It's meaningless. Therefore, by measuring the water level in the water suction well, there is a method for supplying lubricating water to the bearings when the water level drops to a preset water level, that is, lower than the pumping start water level of the chamber shaft pump. He had been hired.

[Problems to be Solved by the Invention] However, in this method of supplying lubricating water to the bearing based on the water level of the water suction well, cases where the water surface of the water suction well is calm and undulating are taken into account. Normally, it was necessary to set the water level at which the supply of lubricating water was stopped to a high level, taking into account the situation where the water was rippling.

However, in such a control method, when the water surface is relatively calm, lubricating water is supplied even though pumping operation is in progress. In other words, the wasted supply of lubricating water continues for a long time, making it impossible to prevent unnecessary water from being poured into the bearing.

The present invention was made by focusing on the fact that in a pump using an induction motor as a drive source, as the load on the pump becomes lighter, the phase difference between the voltage and current of the induction motor's power supply increases. The object of the present invention is to provide a method for supplying lubricating water to a bearing of an induction motor-driven pump, which can reliably supply lubricating water to the bearing while controlling it to the minimum necessary level.

[Means for Solving the Problems] In order to achieve the above object, the method of supplying lubricating water to the bearings of an induction motor-driven pump according to the invention detects the phase difference between voltage and current in the power circuit of the driving induction motor. , When this detected phase difference is larger than a set value that is an intermediate value of each phase difference during submerged operation and pumped water operation, lubricating water is supplied to the bearing of the pump main shaft, and the detected phase difference is increased to the set value. , the supply of lubricating water to the bearing of the pump main shaft is stopped.

[Function] By doing the above, when the induction motor is operated at the rated load or an actual load close to it due to pump operation, the phase difference between the detected voltage and current is small and does not reach the set value. , the supply of lubricating water to the bearing of the pump main shaft is stopped.

In addition, if the induction motor is operated with no load or light load due to air operation, the detected phase difference becomes larger than the set value and lubricating water is supplied to the bearing of the pump main shaft. be done.

[Embodiment] FIG. 1 shows an induction motor-driven chamber shaft pump to which the method of supplying lubricating water to the bearings of an induction motor-driven pump according to the invention is applied. In FIG. 1, the main shaft 2 of the chamber shaft pump 1 is fixed to a bearing 5 fixed to the base of the guide vane 4 above the impeller 3 and at approximately the same height as the floor 7 of the water suction well 6. It is rotatably supported by a bearing 8 and rotationally driven using an induction motor IM as a drive source.

The bearings 5 and 8 are each made of ceramic such as silicon carbide, and are each provided with a lubricating water supply system 9.
Lubricant water for lubrication and cooling is supplied from the

The lubricating water supply system 9 includes a lubricating water supply source 9A, a pipe line 9B that communicates the lubricating water supply source 9A with the bearings 5 and 8, and a valve such as a solenoid valve or an electric ball valve interposed in the pipe line 9B. It is composed of 9C. Therefore, when the valve 9C is opened, lubricating water is supplied from the lubricating water supply source 9A to the bearing 5.8, and when the valve 9C is closed, the lubricating water supply to the bearing 5.8 is stopped.

A phase difference detector 10 that detects a phase difference between voltage and current and outputs a detection signal corresponding to the phase difference is connected to the power circuit IMC of the induction motor IM. This phase difference detector 10
The detection signal outputted by is sent to the water injection control means 11. The water injection control means 11 compares the detection signal with a preset setting value, and when the detection signal is larger than the setting value based on the comparison result, sends an opening control signal to the valve 9C of the lubricating water supply system 9. , and when the detection signal is smaller than the set value, a closing control signal is output to the valve 9c. induction motor I
In M, due to the presence of the excitation current whose phase is delayed by 90 degrees with respect to the power supply voltage, the lighter the load, the larger the phase difference between the voltage and the current becomes. In view of this, the above set value is determined by the phase difference when the induction motor IM is operated at the rated load or an actual load close to it, such as during pumping operation, and when there is no load or light load, such as during submerged operation. The phase difference is set to correspond to any phase difference between the two when operating.

In addition, in the chamber shaft pump 1, the impeller 3 is disposed above the lowest water level LWL inherent to the pump, which sucks air if the suction port depth is less than this, and the impeller 3 is disposed below the impeller 3, that is, the impeller An intake pipe 13 is provided which opens into the vehicle interior and has an air/water switching intake valve 12 interposed therebetween. Therefore, when the water level falls, when the water level reaches a predetermined level between the pumping start water level HWL at the impeller inlet level and the lowest water level (pumping cutoff water level) LWL, the intake valve 12 is opened to send air into the inlet of the impeller 3. Switches from pumping operation to submerged operation, and when the water level rises, when the water level in the water intake well reaches the inlet level HWL of the impeller 3, the intake valve 12 is opened,
The system switches from aerial operation to pumping operation while sucking up residual air.

The opening and closing of the intake valve 12 is performed based on a signal outputted from the pumping start water level HWL or the lowest water level LWL to the intake valve 12 by detecting the pumping start water level HWL or the lowest water level LWL using a water level gauge (not shown).

Next, the procedure for supplying lubricating water to the bearing 5.8 will be explained.

In the operating state of the chamber shaft pump 1 in which the main shaft 2 is rotationally driven, if the water level in the water suction well 6 is equal to or higher than the pumping start water level HWL, the intake valve 12 of the intake pipe 13 is closed, and the impeller 3 Pumping operation is performed because water is sucked up. In this case, the bearing 5.8 will be lubricated and cooled by the self-lifted water sucked up by the impeller 3.

Even if the water level drops below the pumping start water level HWL due to continued pumping operation, the intake valve 12 will remain closed until the water level falls to the pumping cutoff water level LWL, and the bearings 5 and 8 will be closed due to self-pumping. Lubrication and cooling continue.

As described above, when the induction motor IM is operated under actual load during pumping operation, the phase difference between the voltage and current of the power circuit of the induction motor is small, and the phase difference between the voltage and current of the power circuit of the induction motor IM is small. The output detection signal is smaller than the set value set by this water injection control means 11. Therefore, the valve 9C is closed by the control signal output from the water injection control means 11, and the lubricating water supply system 9 is supplied to the pump main shaft 2.
The supply of lubricating water to the bearings 5 and 8 is stopped.

When the water level drops to around the pumping cutoff water level LWL, the intake valve 1
2 is opened to send air to the inlet of the impeller 3, and the pumping operation is switched to the air operation.

When the induction motor IM is under no load or light load due to air operation, the phase difference increases, and the detection signal output from the phase difference detector 10 to the water injection control means 11 becomes larger than the set value. As a result, the control signal output from the water injection control means 11 is switched to open the valve 9c. By opening the valve 9C, lubricating water is supplied from the lubrication supply system 9 to the bearings 5 and 8 of the pump main shaft 2, and the bearings 5 and 8
lubrication and cooling will be provided.

As described above, when the chamber shaft pump 1 is switched to submerged operation and the bearings 5 and 8 are no longer lubricated by self-pumped water, they are quickly lubricated by the lubricating water supplied from the lubricating water supply system 9 and stabilized. Operation can be continued, and unnecessary supply of lubricating water during pumping operation can be reliably avoided.

As the submerged operation continues, the water level in the water intake well 6 rises,
When the pumping start water level HWL is reached, the pumping operation is switched to as described above, and the bearings 5 and 8 are lubricated by the self-pumping water.

In this way, the submersible operation of the indoor shaft pump 1 lubricates and cools the bearing 5°8 with the lubricating water supplied from the lubricating water supply system 9, so it is a preliminary standby operation in which dry operation continues for a long time. Ceramic bearings 5 and 8 can also be used in chamber shaft pumps that perform atmospheric control operation.

It goes without saying that the invention is not limited to the above-mentioned chamber shaft pump, but can also be applied to other pumps that can be operated in air.

[Effects of the Invention] According to claim 1, lubricating water can be reliably supplied to the bearings during submerged operation to continue stable operation, and lubricating water is not wasted on the bearings during pumping operation. Therefore, it is possible to use ceramic bearings even in pumps that perform advance standby operation or air management operation, which has the effect of improving versatility.

Moreover, since the amount of lubricating water supplied to the bearing can be suppressed to the necessary minimum, it is possible to save lubricating water and power for supplying it.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a chamber shaft pump employing the method of the invention. 2...Main shaft 5.8...Ceramic bearing (bearing) 9...Lubricating water supply system 10...Phase difference detector 11...Water injection control means ■G-Induction motor IMC...Power circuit

Claims (1)

[Claims] (1) Detect the phase difference between the voltage and current in the power circuit of the drive induction motor, and when this detected phase difference is larger than the set value, which is the intermediate value of the phase differences during air operation and pumped water operation, the pump A bearing of an induction motor-driven pump, characterized in that lubricating water is supplied to a bearing of a main shaft, and when the detected phase difference is smaller than the set value, the supply of lubricating water to the bearing of a pump main shaft is stopped. Lubricating water supply method.