JP2626828B2 - Lubricating water supply method for bearing of induction motor driven pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for supplying lubricating water to bearings of a pump driven by an induction motor.

[Prior Art] For example, as a bearing for a vertical shaft pump, a ceramic bearing that is lubricated and cooled by self-lifting water and can continue stable operation is employed.

In this type of bearing, the dry operation is performed for a very short time immediately after the start of the pump, and after this short time elapses, lubrication and cooling are immediately performed by the self-lifting water, and stable operation is started. That is, in the ceramic bearing, the 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 stations installed in waterways has become large and rapid. In such a situation, the dry operation is continued even when the water level of the suction well at the drainage pump station is equal to or lower than the pumping cutoff water level of the vertical shaft pump, and the preliminary standby operation or the air management operation that precedes the operation state of the pump is performed. Yes, it is.

In the vertical shaft pump used for the preceding standby operation and the air management operation, the dry operation will be continued for a long time,
During this time, lubrication water is not supplied to the bearing. Therefore, it has not been possible to adopt a ceramic bearing having a dry operation time limited to a short time for a vertical shaft pump that performs the preliminary standby operation or the air management operation.

As a means for solving such a problem, it is conceivable to supply lubricating water to the bearing from the outside.In this case, it is not possible to continue supplying lubricating water from the outside despite the pumping operation. It is meaningless. Therefore, a method of supplying lubricating water to the bearing is adopted by measuring the water level of the water absorption well, and when the water level falls to a predetermined water level, that is, a water level lower than the pumping start water level of the vertical shaft pump. It had been.

[Problems to be Solved by the Invention] However, as described above, in the method of supplying lubricating water to the bearing based on the water level of the water absorption well, consideration is given to the case where the water surface of the water absorption well is calm and the case where it is wavy. Usually, in consideration of the case where the lubrication is wavy, it is necessary to set the supply stop water level of the lubricating water to a relatively high level with a margin.

However, in such a control method, when the water surface is relatively calm, lubricating water is supplied even though the bearings are being pumped and lubricated and cooled by self-pumping. become. That is, wasteful supply of lubricating water is continued for a long time, and waste of power consumption due to unnecessary supply of lubricating water to the bearing from the outside is inevitable.

The present invention has been made in view of the above circumstances,
The load of the induction motor for driving the pump is reduced during the in-air operation, so that the primary current and the input power of the induction motor are reduced, and the primary load of the induction motor for driving the pump is increased during the pumping operation. By effectively utilizing the increased input power, the external lubricating water can be accurately supplied to the bearings regardless of the water surface condition of the water intake well, and the lubricating water supply amount and power It is an object of the present invention to provide a method of supplying lubricating water to bearings of an induction motor driven pump that can minimize consumption.

[Means for Solving the Problems] In order to achieve the above object, a lubricating water supply method for a bearing of an induction motor driven pump according to the present invention includes the steps of: , Is switched from pumping operation to air operation, and
When the water level of the water intake well rises to the pumping start water level that is set higher than the pumping cutoff water level due to the in-air operation, a primary pump driving induction motor that is a driving source of a pump that is switched from the in-air operation to the pumping operation. Means for detecting current or input power, the primary level of detection by the detecting means in a state where the water level of the suction well drops to the pumping cutoff water level with the pumping operation and the pump is switched to the air operation. When the current or the input power becomes smaller than a first set value which is set as an intermediate value between the maximum primary current or the maximum input power during the in-air operation and the minimum primary current or the minimum input power during the pumping operation, Externally start supplying lubrication water for cooling and lubrication to the bearings supporting the main shaft, and the water level of the water intake well rises to the above-mentioned pumping start water level due to aerial operation The primary current or input power detected by the detection means in a state where the pump is switched to the pumping operation is the maximum primary current or maximum input power during in-air operation and the minimum primary current or maximum input power during pumping operation. When an intermediate value is larger than a second set value which is equal to or larger than the first set value,
The supply of lubricating water for external lubrication and cooling to a bearing that supports the pump main shaft is stopped.

[Operation] According to the present invention, the activated pump is switched from the pumping operation to the aerial operation due to a decrease in the water level of the suction well due to its pumping operation, and the water level of the intake well is increased due to the aerial operation. During the pumping operation, the pump driving induction motor is operated at a rated load or an actual load close to the rated load, and the primary operation of the induction motor is continued during the pumping operation. The current or input power also increases according to the load, and during the air operation, the pump driving induction motor is operated with a light load or no load, and the primary current or the input power of the induction motor also decreases according to the load. . As described above, in a state where the pump is switched to the pumping operation in accordance with the rise in the water level of the water intake well, the primary current or the input power of the induction motor becomes larger than that in the air operation, and the detected primary current or the input power becomes the first and the input power. When the value becomes larger than the second set value, the supply of lubricating water for external lubrication and cooling to the bearing that supports the pump main shaft is stopped, and the bearing is lubricated and cooled by self-lifting water. In the state where the pump is switched to the air operation due to the decrease in the water level of the water intake well, the primary current or the input power of the induction motor becomes significantly smaller than that of the pumping operation, and the detected primary current or the input power becomes the first set value. When it becomes smaller, the supply of lubricating water for lubrication and cooling is started from the outside to the bearing that supports the pump main shaft, and the bearing receives external lubricating water. It will be lubricated and cooled I. As a result, the lubrication and cooling functions for the bearings are maintained during both the pumping operation and the in-air operation, so that a stable pump operation can be continued. It is possible to minimize.

[Embodiment] Fig. 1 is a schematic diagram showing an example of an apparatus for externally supplying lubricating water to bearings 5 and 8 which support a main shaft 2 of an induction motor driven vertical pump 1 by employing the method of the present invention. is there. In FIG. 1, a main shaft 2 of a vertical pump 1 has a bearing 5 fixed to a base of a guide vane 4 above an impeller 3 and a water absorption well 6.
The bearing 8 is rotatably supported by a bearing 8 fixed at substantially the same level as the floor surface 7 and is rotationally driven by the induction motor IM as a drive source.

Each of the bearings 5 and 8 is formed of ceramics such as silicon carbide,
Is supplied with lubricating water for lubrication and cooling.

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

A current detector 10 that detects a primary current of the induction motor IM and outputs a detection signal corresponding thereto is connected to a power circuit IMC of the induction motor IM. The detection signal output from the current detector 10 is sent to the water injection control means 11. The water injection control means 11 compares the detection signal with a preset set value, and in the comparison, when the detection signal is smaller than the first set value, sends the open control signal to the valve 9C of the lubricating water supply system 9. When the detection signal is larger than the second set value,
The closed control signal is output to 9C. The primary current of the induction motor IM increases as the load increases. The first and second set values are determined by an induction motor as in a pumping operation.
Predetermined primary current value between the primary current value when the IM is operating at or near the rated load and the primary current value when operating at no load or light load such as in air operation That is, it is set to a value between the primary current value at the minimum load when pumping is performed and the maximum primary current value when pumping is not performed.
And the second set value may be the same,
The second set value may be slightly larger than the first set value.

In the vertical shaft pump 1, the impeller 3 is disposed above the pump-specific minimum water level LWL which sucks air when the depth of the suction port is less than this, and the impeller 3 is located below the inlet of the impeller 3, ie, the impeller. It is provided with an intake pipe 13 which is opened to the chamber and in which a water / water switching intake valve 12 is interposed midway. Therefore, when the water level drops, the minimum water level (pumping cutoff water level) LWL
, The intake valve 12 is opened, air is sent into the inlet of the impeller 3 to switch from pumping operation to air operation, and when the water level rises, the water level of the water intake well is changed to the inlet level HWL of the impeller 3.
Is reached, the intake valve 12 is closed, and it is possible to switch from the in-air operation to the water pumping operation while sucking up residual air.

The opening and closing of the intake valve 12 is performed based on a signal which is output to the intake valve 12 by detecting the pumping start water level HWL or the minimum water level LWL by a water level gauge not shown.

Next, a procedure for supplying lubricating water to the bearings 5 and 8 will be described.

In the operating state of the vertical shaft pump 1 in which the main shaft 2 is rotationally driven, if the water level of the 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
The pumping operation is performed because the water is sucked up.
In this case, the bearings 5 and 8 are lubricated and cooled by the self-pumping water drawn by the impeller 3.

Even if the water level falls below the pumping start water level HWL due to the continuation of the pumping operation, the closed state of the intake valve 12 is maintained until the water level drops to the pumping cutoff water level LWL, and the bearings 5 and 8 by self-pumping operate. Lubrication and cooling are continued.

In the state where the pumping operation is performed, the induction motor IM is in the actual load operation, and the detection signal of the primary current of the induction motor IM by the current detector 10 is the second set value set by the water injection control means 11. Greater than. Therefore, the valve 9C is closed by the control signal output from the water injection control means 11, and the supply of the lubricating water from the lubricating water supply system 9 to the bearings 5, 8 of the pump main shaft 2 is stopped.

When the water level drops near the pumping cutoff water level LWL, the intake valve 12
And air is fed into the inlet of the impeller 3 to switch from pumping operation to air operation.

As described above, when the induction motor IM is in no-load or light load due to the in-air operation, the primary current of the induction motor IM is significantly reduced, and the detection signal becomes smaller than the first set value of the water injection control means 11. As a result, the control signal output from the water injection control means 11 is switched to one that opens the valve 9C. Valve 9C
Opening of the lubrication supply system 9, the bearings 5 of the pump main shaft 2,
Lubricating water is supplied to 8, and lubrication and cooling of the bearings 5, 8 are performed.

As described above, when the vertical shaft pump 1 is switched to the in-air operation and the bearings 5 and 8 are not lubricated by the self-pumping water, the lubricating water supplied from the lubricating water supply system 9 quickly lubricates the lubricating water and the stable operation. Can be continued, and the needless supply of lubricating water during the pumping operation can be reliably eliminated.

By continuing the aerial operation, when the water level of the suction well 6 rises and reaches the pumping start water level HWL, the operation is switched to the pumping operation as described above. Therefore, the induction motor IM is operated at the rated load or an actual load close thereto. As a result, the primary current of the induction motor IM rises more than in air operation, and when the detection signal of the rising primary current reaches the second set value, the bearing 5 by the lubricating water supply system 9 , 8 is stopped and the bearings 5, 8 are lubricated by self-lifting.

As described above, the lubricating water supplied from the lubricating water supply system 9 lubricates and cools the bearings 5 and 8 during the aerial operation of the vertical shaft pump 1, so that the preliminary standby operation in which the dry operation is continued for a long time Ceramic bearings 5 and 8 can also be used for vertical shaft pumps that perform air management operation.

FIG. 2 is a schematic configuration diagram showing another example of a device for externally supplying lubricating water to bearings 5 and 8 which support the main shaft 2 of the induction motor driven vertical shaft pump 1 by employing the method of the present invention. However, the vertical pump for supplying lubricating water to the bearings by the apparatus of FIG. 2 is the same as the vertical pump 1 of FIG. 1, and is omitted in FIG. Also, the lubricating water supply system 9 is the same as that shown in FIG. 1, and a detailed description thereof will be omitted here.

In the device shown in FIG. 2, the power circuit of the induction motor IM
A power detector 10 'for detecting a primary current and an input voltage of the induction motor IM to obtain input power of the induction motor IM and outputting a detection signal corresponding to the input power is connected to the IMC. The detection signal output from the detector 10 'is sent to the water injection control means 11'. The water injection control means 11 'compares the detection signal with a preset set value, and when the detection signal is smaller than the first set value, as in the case of FIG. 1, the valve 9C of the lubricating water supply system 9 The control signal is output to the valve 9C when the detection signal is larger than the second set value. The input power of the induction motor IM naturally increases as the load increases, as does the primary current. The first and second set values are an input power value when the induction motor IM is operated at the rated load or an actual load close to the rated load as in the case of the pumping operation, and a no-load value as in the case of the in-air operation. Or a predetermined input power value corresponding to the input power during the input power value when operating at a light load,
That is, the value is set to a value between the input power value at the minimum load when pumping is performed and the maximum input power value when pumping is not performed. As in the case described with reference to FIG. 1, the first setting value and the second setting value may be the same value, but may be different setting values as needed.

In FIG. 2 as well, when the vertical shaft pump (not shown) performs the pumping operation and the induction motor IM is in the actual load operation, the detection signal of the input power of the induction motor IM is supplied to the water injection control means 1.
Therefore, the valve 9C is closed by a control signal output from the water injection control means 11 'and the bearings 5, 8 of the pump main shaft 2 are supplied from the lubricating water supply system 9. Is stopped. Also,
When the vertical shaft pump operates in the air and the induction motor IM becomes no load or light load, the detection signal of the input power of the induction motor IM becomes smaller than the first set value of the water injection control means 11 ', and the water injection control means The valve is controlled by the control signal output from 11 '
9C is opened, and the bearings 5 and 5 of the pump
8 is supplied with lubricating water.

That is, the lubrication and cooling of the bearings 5 and 8 are performed by the lubricating water supplied from the lubricating water supply system 9 only during the in-air operation, also by the method according to the second invention described with reference to FIG. During the pumping operation, the supply of the lubricating water from the lubricating water supply system 9 is stopped, and the lubrication and cooling of the bearings 5 and 8 can be performed by self-pumping.

Needless to say, the first and second inventions can be applied not only to the vertical shaft pump as described above, but also to other pumps capable of performing aerial operation.

[Effects of the Invention] As described above, according to the present invention, the load of the pump driving induction motor greatly changes during the pumping operation and the air operation, and the primary current and input power of the induction motor also change accordingly. By making effective use of the change in size, regardless of the water surface condition of the water intake well, the aerial operation will be able to supply lubricating water to the bearings accurately from the outside to maintain stable operation. In addition, during pumping operation in which predetermined lubrication and cooling are maintained by self-pumping, the supply of unnecessary lubricating water from outside to the bearing can be stopped. Therefore, it is possible to use a ceramic bearing as a bearing for a main shaft of a pump performing a preliminary standby operation, an air management operation, etc., not only to improve versatility, but also to reduce the amount of lubricating water supplied to the bearing from the outside. The lubricating water and the power required to supply the lubricating water can be reduced to a minimum necessary amount, thereby reducing wasteful consumption.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an apparatus that employs the method of the present invention, and FIG. 2 is a schematic configuration diagram illustrating another example of the apparatus. 2 Main shaft 5, 8 Ceramic bearing (bearing) 9 Lubricating water supply system 10 Current detector 10 'Power detector 11, 11' Water injection control means IM Induction motor IMC … Power circuit

Claims (1)

(57) [Claims] When the water level of the intake well drops to the pumping cutoff level with the pumping operation, the pumping operation is switched to the aerial operation, and the water level of the suction well becomes higher than the pumping shutoff level with the aerial operation. Having a means for detecting the primary current or input power of a pump driving induction motor that is a drive source of a pump that is switched from aerial operation to pumping operation when rising to a set pumping start water level that is set high, the pumping operation Accordingly, the primary current or input power detected by the detection means in a state where the water level of the suction well drops to the pumping cutoff water level and the pump is switched to the in-air operation is the maximum primary current or the maximum in the in-air operation. When the input power and the minimum primary current during the pumping operation or a first set value set as an intermediate value between the minimum input powers become smaller than the first set value, the bearing for supporting the pump main shaft is supported. Supply of lubricating water for lubrication and cooling from outside, and the detection in a state where the water level of the water intake well rises to the pumping start water level due to aerial operation and the pump is switched to the pumping operation The primary current or input power detected by the means is an intermediate value between the maximum primary current or maximum input power during in-air operation and the minimum primary current or minimum input power during pumping operation, and is equal to or higher than the first set value. An induction motor-driven pump, which stops supply of lubricating water for external lubrication and cooling to a bearing that supports the pump main shaft when the value exceeds a second set value that is set to a large value. Lubrication water supply method for bearings.