JPH0758078B2 - Operating method and operating device for self-priming pump - Google Patents

Description

The present invention relates to a driving method and a driving device for improving the self-priming characteristic of a self-priming pump.

[Conventional technology]

Generally, self-priming pumps are roughly classified into the following two types, that is, (a) a centrifugal (spiral) pump is devised so that the pump itself operates as a vacuum pump from the start to the end of self-priming. And (b) a vacuum pump provided separately in conjunction with the pump main shaft performs the priming action of the pump body and the suction pipe at the same time when the pump main shaft is activated.

The present invention belongs to (a) above, and an example thereof will be described with reference to the drawings. 1 is a casing of a self-priming centrifugal pump, and a suction port 2 is provided above one side (left side in the figure). In the interior of the casing 1, a suction chamber 3 communicated with the suction port 2 is provided with partition walls 4, 4 and an impeller 5, a diffuser 6 surrounding the impeller 5, and an air / water separation chamber 7 and the like at the upper portion. It is provided separately from the pump chamber 8.

A check valve (flap valve) 9 is provided in the upper part of the suction chamber 3 so as to be separated from the suction port 2, so that water necessary for self-priming the inside of the pump can be provided before the operation. In addition to ensuring this, the backflow of water when the pump is stopped is prevented, and the inside of the pump is always filled with water. In the figure, 10 is a constant speed electric motor, 11 is an electric motor shaft, 12 is a partition flange, 13 is a shaft sealing device (mechanical seal), and 14 is a drain plug.

When the pump is started, make-up water (priming water) is injected into the pump casing 1 and the impeller 5 is rotated in a state of being filled with water, so that the make-up water in the suction chamber 3 is sucked from the inlet of the impeller 5 and The air is discharged from the car 5 into the pump chamber 9, but at this time the suction chamber 3 becomes a negative pressure, so the check valve 10 is opened to suck the air on the suction side from the suction port 2 and to the pump chamber 9 together with the air. Is ejected. The steam-water mixture discharged into the pump chamber 9 is separated in the steam-water separation chamber 8, only water is returned into the diffuser 6, enters the blade of the rotating impeller 5, and enters the suction chamber 3 into the impeller. Together with the newly sucked air, it is discharged again to the pump chamber 9, separated again in the steam separation chamber 8, the air is removed from the discharge port 12, and the water returns to the impeller 5 again. By repeating such operations, the air on the suction side is gradually exhausted and the self-priming action proceeds.

As a means for returning only the water separated in the steam separation chamber 8 into the blade of the impeller 5, for example, two diffusers (1
Divided into pairs, and surround each of the impellers,
There are those arranged substantially symmetrically on the left and right, and those in which the pump chamber 8 and the suction chamber 3 are made to communicate with each other through a valved circulation passage.

[Problems to be Solved by the Invention]

The self-priming characteristics of the self-priming pump described above are greatly affected by the peripheral speed of the impeller. That is, when the peripheral speed of the impeller is high, the self-priming time is short and good self-priming characteristics are obtained. However, when the peripheral speed is low, the self-priming time is long or the self-priming is not possible. It is in.

On the other hand, the determination of the peripheral speed of the impeller has hitherto been influenced only by the size required to obtain the required total pump head during steady operation. In other words, the peripheral speed of the impeller is a peripheral speed that satisfies the pump performance during steady operation, and structural improvements have been made to improve the self-priming characteristics.
There was a problem that the effect was not sufficient.

Further, conventionally, a method of controlling the operation by changing the rotation speed of the impeller is known, but all of these control methods are
The pressure and flow rate were controlled to save energy during steady operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for operating a self-priming pump that solves the above-mentioned problems of the prior art and improves self-priming characteristics.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the operating method of the present invention is characterized in that, in the self-priming pump, the rotation speed during self-priming operation is set to be higher than that during steady operation by using a variable speed device.

Further, in the self-priming pump, a means for detecting the self-priming action and a variable speed device interlocking with the sensing means are provided, and the impeller in the self-priming operation is operated at a speed higher than the rotation speed in the steady operation. It is characterized by rotating.

[Work]

The self-priming pump goes into a steady operation after the self-priming operation after starting, but during the self-priming operation, air and water are mixed in the impeller, and the apparent specific gravity of the fluid is small. Therefore, the shaft power during self-priming operation is much smaller than that during steady operation. Therefore, during the self-priming operation, the rotation speed can be increased until the load becomes the same as in the steady operation.

According to the operating method of the present invention, after the engine is started, the maximum rotation speed is set to the above value, and thus, good self-priming characteristics, that is, a large self-priming height and a short self-priming time can be obtained.

Also, during steady operation of the pump, when a large amount of air is sucked in, the pump action is temporarily interrupted, and when a situation (phenomenon) that requires self-priming action occurs again, the period during which the pump discharge pressure is decreasing By the detection means such as a sensor for detecting the inside, the rotation speed of the impeller is increased during the operation of the detection means such as the sensor, that is, during the self-priming action, so that the self-priming time is shortened,
The pump operation at steady state is promptly restarted.

〔Example〕

Next, a self-priming pump for implementing the operating method of the present invention will be described with reference to the drawings.

The main body of the self-priming pump in the above drawings is no different from the conventional one described above, and the inside of the casing 1 surrounds the suction chamber 3 communicated with the suction port 2 via the check valve 9 and the impeller 5. The diffuser 6 and the pump chamber 8 having the water / water separation chamber 7 on the upper side are separated by the partition walls 4, 4, and at the time of start-up, makeup water (priming water) in the casing 1 is sucked from the inlet of the impeller 5 and the pump chamber Only the water discharged into 8 and separated in the steam separation chamber 7 is returned to the inside of the impeller, mixed with the suction side air and steam, and discharged again into the pump chamber 8 to repeat such operation. While promoting self-priming.

Then, during the self-priming operation after the start, as described above, the inside of the impeller is in a mixed state of air and water, and the apparent specific gravity of the fluid is small. Therefore, the impeller driven via the shaft 11 of the electric motor 20. The axial force of No. 5 is much smaller than that during steady operation.

Therefore, in this embodiment, the variable speed electric motor 20 is used as the electric motor, and after the start, the self-priming operation is performed at the maximum rotation speed of the variable speed electric motor 20. Upon entering, the pump discharge pressure at that time is detected by a pressure sensor or the like, and the rotation speed of the electric motor 20 is automatically reduced to the rotation speed during steady operation.

According to this embodiment, by increasing the rotation speed of the impeller 5 and increasing the peripheral speed of the impeller 5 during the self-priming operation as described above, the self-priming action is promoted and good self-priming characteristics are obtained. That is, a large self-priming height and a short self-priming time can be obtained.

In addition, since the variable speed electric motor 20 is used in this embodied system, after the self-priming action is completed, even after the pump enters the steady operation, the optimum head according to the usage state (environmental conditions),
By changing the rotation speed so as to obtain the amount of water and controlling the pressure and the flow rate, it is possible to achieve the energy saving effect without waste.

The switching of the rotation speed of the impeller described above is done by detecting the end of self-priming action with a pressure sensor as described above, as well as by installing it on a pressure switch, discharge side pipe, etc., and opening and closing (ON, A method (means) for detecting using an electrode that turns off) is conceivable, or a timer that is set to operate at the same time as starting and cut off after a lapse of a certain time is used to make the impeller maximum rotation speed at the same time as the pump starts. It is also possible to drive with a relay and activate the relay when the timer expires to switch to the rotation speed during steady operation.

Further, a detecting means such as a pressure sensor, a pressure switch, an electrode, etc. for detecting that the pump discharge pressure value is equal to or lower than a predetermined value to detect that self-priming is being performed is provided, and the detecting means and the variable speed electric motor are interlocked. It is also possible to allow it. With such a configuration, during a steady operation of the pump, when a large amount of air is sucked in, the pump action is temporarily interrupted, and a situation (phenomenon) in which self-priming action is required occurs again,
Since the rotational speed of the impeller is increased during the operation of the detecting means, that is, during the self-priming operation, the self-priming time is shortened, and the pump operation in the steady state is restarted promptly.

In the above-described embodied device, the device in which the impeller is configured by a spiral pump impeller has been described, but it is needless to say that it can be similarly applied to a self-priming pump configured by a centrifugal pump (Wesco pump) impeller. Although the device using the variable speed electric motor as the variable speed device has been described, it is also possible to drive the self-priming pump by the constant speed electric motor via the transmission to increase the rotation speed during the self-priming to a value higher than that in the steady state. .

〔The invention's effect〕

As described above, according to the present invention, the rotation speed during self-priming operation of the self-priming pump is made larger than that during steady operation to improve self-priming characteristics, and large self-priming height and short self-priming performance. The sucking time can be obtained. Therefore, the self-priming time is shortened and the steady-state pump operation is promptly restarted not only at the time of start-up but also when a large amount of air is sucked in and the pump action is temporarily interrupted during the pump operation.

Further, since the variable speed device is used, the rotational speed during steady operation is changed to control the pressure and the flow rate, so that the optimum operation corresponding to the use condition can be performed and an energy saving effect can be achieved.

[Brief description of drawings]

The drawings are cross-sectional views showing an embodiment of a self-priming pump for carrying out the operating method of the present invention. 1 ... Pump casing, 2 ... Suction port, 3 ... Suction chamber, 4 ... Partition wall, 5 ... Impeller, 6 ... Diffuser,
7 ... Air-water separation chamber, 8 ... Pump chamber, 9 ... Check valve, 1
0,20 …… motor, 11 …… motor shaft.

Claims (2)

[Claims] 1. A method of operating a self-priming pump, wherein the rotation speed of the self-priming pump during self-priming operation is set higher than that during steady operation by using a variable speed device. 2. A self-priming pump, which is provided with a means for detecting a self-priming action and a variable speed device interlocking with the sensing means, so that the impeller during the self-priming operation can be operated at a rotational speed during steady operation. An operating device for a self-priming pump, which is adapted to rotate at a high speed.