JPH08219083A - Pumping device with self-control function - Google Patents

Abstract

PURPOSE: To provide a pumping device having self-control mechanism provided at a pump itself so as to control discharge pressure to be constant to load fluctuation. CONSTITUTION: A pumping device is provided with a vortex chamber 7 disposed at the suction port 6 of a centrifugal pump, and a contraflow pipeline communicated with the peripheral part of the vortex chamber 7 from the discharge port of the centrifugal pump. The outflow port 12a of the contraflow pipeline and the inflow port 10 of a transported fluid are so formed that a transported fluid flowing backward from the discharge port 11 of the pump collides with the transported fluid flowing into the peripheral part of the vortex chamber 7 so as to throttle the transported fluid and thereby to obtain a sharp diode characteristic, thus having the function of self-controlling the discharge pressure of the pump to be almost constant to the load fluctuation of the pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump device having a self-control function which constantly controls the discharge pressure of the pump to be substantially constant against fluctuations in the pump load.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing the lift (H) / flow rate (Q) characteristics of a conventional general centrifugal pump. As shown in the figure, when the discharge side load (pipe line resistance) changes, the operating point of the pump shifts from the point A to the point B, and the discharge pressure (H) and flow rate (Q) of the pump change. To do. The change in the discharge pressure may cause an inconvenience, for example, causing an increase or decrease in the water pressure on the demand side.

Therefore, in the conventional centrifugal pump, in order to keep the discharge pressure of the pump constant against the fluctuation of the load,
Various methods have been taken. As an example, there is provided a rotation speed control device for controlling the rotation speed of the pump, and the pump rotation speed is controlled according to the fluctuation of the pump load, or a pressure control valve is provided at the pump discharge port to change the pump load. There is a method of controlling the pressure control valve.

[0004]

However, all of the above-mentioned conventional methods require addition of special equipment such as a rotational speed control device and a pressure control valve having a complicated structure, and a drive device therefor, and the entire pump device. There is a problem in that it is complicated and expensive and requires complicated work such as installation and adjustment.

The present invention has been made in view of the above problems, and controls the discharge pressure to be constant with respect to a change in load.
An object of the present invention is to provide a pump device in which the pump itself has a self-control mechanism.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to a vortex chamber arranged at the suction port of a centrifugal pump and a backflow pipe communicating from the discharge port of the centrifugal pump to the outer peripheral portion of the vortex chamber. And a passage is provided, and the outlet of the backflow pipe and the inlet of the transport fluid are squeezed by colliding the transport fluid flowing back from the discharge port of the pump with the transport fluid flowing into the outer peripheral portion of the vortex chamber. It is characterized in that a steep diode characteristic is obtained so as to have a function of always self-controlling the discharge pressure of the pump to be substantially constant with respect to the fluctuation of the pump load.

The backflow pipe is arranged so that a backflow fluid flows in a tangential direction of an outer peripheral portion of the vortex chamber and the transport fluid flows in a substantially radial direction of the vortex chamber and collides with the backflow fluid. The angle formed by the flow direction of the backflow fluid and the flow direction of the transport fluid is greater than 90 °.

[0008]

According to the present invention, as described above, the vortex chamber and the reverse flow passage communicating from the discharge port to the outer peripheral portion of the vortex chamber are provided in the suction port of the centrifugal pump, and the transport fluid flowing backward from the pump discharge port is swirled. It is configured so as to collide with the transport fluid flowing into the outer peripheral portion of the chamber. Therefore, a steep diode characteristic is obtained in the relationship between the pressure and the flow rate in the vortex chamber. That is, when the pressure of the backflow fluid becomes higher than a certain value, the inflow amount of the transport fluid is throttled, and when the pressure of the backflow fluid falls below the certain value, the inflow amount of the transport fluid increases. By feeding back such characteristics of the vortex chamber, the discharge pressure of the pump can be self-controlled to be substantially constant with respect to changes in the pump load.

In particular, the angle formed by the flow of the backflow fluid that flows in the tangential direction at the outer peripheral portion of the vortex chamber and the flow of the transport fluid that flows in the substantially radial direction is greater than 90 °, and the collisions should be made in a slightly opposite direction. As a result, the diode characteristic can be made steeper, and as a result, the pressure fluctuation on the discharge side of the pump can be made smaller.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 1 is a view showing the structure of a centrifugal pump device according to the present invention. Reference numeral 1 is a pump casing, reference numeral 2 is an impeller housed in the pump casing 1, and reference numeral 3 is a pump main shaft. The impeller 2 is fixed to one end of the pump main shaft 3. The pump main shaft 3 is rotatably supported by bearings 4 and 5. In the centrifugal pump device having the above structure, the pump main shaft 3 is indirectly or directly connected to the main shaft of a drive motor (not shown) via a reduction mechanism or the like. When the drive motor is rotated, the impeller 2 rotates via the pump main shaft 3.

By the rotation of the impeller 2, the transport fluid such as water is sucked from the transport fluid inlet 10, flows into the vortex chamber 7, and further passes through the pump suction port 6 to be pressurized by the impeller 2. , Is discharged from the pump discharge port 11. Incidentally, reference numeral 1
3 is a sealing mechanism. The backflow pipe line 12 is connected between the pump discharge port 11 and the outer peripheral portion of the vortex chamber 7 which is an inlet port of the transport fluid.

FIG. 2 shows a cross section of the vortex chamber 7 taken along the line AA in FIG. As shown in the figure, the outlet 12a of the backflow conduit 12 is provided so that the backflow fluid from the outlet 12a is ejected in the tangential direction of the outer peripheral portion of the vortex chamber 7. The inlet 10 for the transport fluid flowing into the vortex chamber 7 is
With respect to the radial direction. Inlet 10
The transport fluid flowing in from the outflow port 12 a of the backflow pipe 12
It is arranged so as to collide with the backflow fluid ejected from. Then, the backflow fluid gives a swirl force to the transport fluid to generate a swirl flow shown by an arrow in the figure. Reference numeral 9 in the drawing denotes a stay, which supports the vortex chamber 7 and imparts a moving direction of a radial component to the swirling flow to guide it to the suction port 6.

FIG. 3 shows the configuration of the control circuit of this pump device. The pressure of the transport fluid at the inlet 10 of the vortex chamber 7 is P _S , and the flow rate is Q _S. The pressure of the backflow fluid in the vortex chamber outer periphery P _C, the flow rate Q _C. Let P _{0 be} the pressure of the transporting fluid at the pump suction port 6 and Q ₀ be the flow rate. The pressure of the transport fluid at the pump discharge port 11 that is pressurized by the impeller 2 of the pump is P ₁ . At this pressure P ₁ , the flow rate Q ₁ is supplied to the load side via the line resistance R ₁ . Further, the flow rate Q _f passes through the backflow pipe 12, and is fed back to the outer peripheral side of the vortex chamber 7 as a backflow fluid having a pressure P _C and a flow amount Q _C by the line resistance R ₁₁ .

FIG. 4 is a model of the shape of the vortex chamber 7. Here, the diameter of the backflow conduit 12 is b _c , and the diameter of the inlet of the transport fluid is b _s . The outer radius of the vortex chamber is r ₁ and the diameter of the suction port is r ₀ . The arrow in the figure indicates the swirling direction of the fluid. The flow direction of the transport fluid inflow port 10 is substantially the radial direction of the vortex chamber 7, but deviates from the radial direction by the supply port angle β. The supply port angle β of the vortex chamber 7 is set to be a negative value, that is, the angle formed by the inflow direction of the backflow fluid and the inflow direction of the transport fluid is larger than 90 °, and the two are slightly opposed to each other. By colliding,
The diode characteristic of the vortex chamber can be made steeper.

Based on the control circuit of FIG. 3 and the model shown in FIG. 4, the basic equations of the control characteristics are as shown in equations (1) to (7).

[0017]

[Equation 1]

The pumping characteristics of the pump can be calculated using these equations. In addition, the characteristics of the vortex chamber modeled in Fig. 4 are calculated by Bichara (Analysis and Modeling of
theVortex Amplifier, Trans. ASME Journal of Basic
This can be calculated by modifying the tangential velocity Vθ _i of Engineering, Vol.91 (1969), pp.755-763) as in equation (8).

FIG. 5 shows an example of the calculation result of the pressure / flow rate characteristic of the vortex chamber. Regarding the relationship between the pressure P and the flow rate Q, the discharge pressure P ₁ of the pump is high, that is, the pressure P _{C of the} backflow fluid.
The state having a large difference between the suction side pressure P ₀ throttled flow rate Q ₀ is substantially constant value, it is seen that the diode characteristics that the flow rate Q ₀ is sharply increased to obtain a low state pressure P _1.

In the figure, the dotted line shows the case where the supply port angle β of the transport fluid in the vortex chamber is −25 °, the solid line shows the case of 0 °, and the alternate long and short dash line shows the case of + 25 °. As is clear from this calculation result, by setting the supply port angle β to a negative value, that is, the angle formed by the flow direction of the backflow fluid and the flow direction of the transport fluid is larger than 90 °. By setting, a steep diode characteristic can be obtained.

FIG. 6 shows calculated values of pump head (H) / flow rate (Q) characteristics when feedback control of the pump is performed using the vortex chamber having the characteristics shown in FIG. FIG.
It is the experimental value which confirmed the calculation result shown in FIG. 6 by experiment.

In the figure, the alternate long and short dash line indicates the case where the feedback control by the vortex chamber is not performed, and the dotted line indicates the supply port angle β of -2.
The case is 5 °, and the solid line is the case where the supply port angle β is 0 °. The bottom line in the figure is the supply port angle β +2
This is the case when the angle is 5 °.

As is apparent from these figures, when the discharge side pressure of the pump is fed back to the suction side by using the vortex chamber having a steep diode characteristic, the pump is compared with the case without feedback control. Discharge pressure P ₁
It can be seen that can be controlled fairly flat regardless of the fluctuation of the flow rate Q ₁ . This effect is particularly remarkable when the supply port angle β is negative and the diode characteristics are steep.

In the above embodiment, an example in which the transport fluid inlet and the backflow conduit outlet are provided at one location in the vortex chamber has been described, but two or more locations may be provided. . Further, a control valve or the like may be provided in the middle of the backflow conduit to adjust the control fluid pressure flowing in the backflow conduit. As a result, it is possible to control the pump discharge pressure more effectively with respect to the fluctuation of the pump load so as to be constant, and to reduce the loss in the vortex element.

[0025]

As described above, according to the present invention, a vortex chamber is provided at the suction port of a centrifugal pump, and a backflow pipe communicating from the discharge port of the centrifugal pump to the vortex chamber is provided. The pump discharge pressure can be controlled to be substantially constant with respect to the load fluctuation on the pump discharge side by a relatively simple means in which the fluid ejected from the outlet collides with the transport fluid flowing into the vortex chamber. . That is, the self-control function of the pump itself has an excellent effect that the discharge pressure can be maintained substantially constant at low cost without using a frequency conversion device or the like.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a structure of a centrifugal pump device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is an explanatory diagram showing a control circuit of a centrifugal pump device according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a model of a vortex chamber of the centrifugal pump device according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing calculation results of pressure / flow rate characteristics of a vortex chamber.

FIG. 6 is an explanatory diagram showing calculation results of pressure / flow rate characteristics of a centrifugal pump.

FIG. 7 is an explanatory diagram showing experimental results of pressure / flow rate characteristics of a centrifugal pump.

FIG. 8 is an explanatory diagram showing pressure / flow rate characteristics of a conventional centrifugal pump.

[Explanation of symbols]

 1 Pump casing 2 Impeller 3 Pump main shaft 4,5 Bearing 6 Pump suction port 7 Vortex chamber 10 Vortex suction port 11 Pump discharge port 12 Reverse flow line 13 Seal mechanism

Claims (2)

[Claims] 1. A vortex chamber disposed at a suction port of a centrifugal pump,
A backflow conduit communicating from the discharge port of the centrifugal pump to the outer peripheral portion of the vortex chamber is provided, and the transport fluid that flows backward from the discharge port of the pump and the flow port of the transport fluid is By colliding with the transport fluid flowing into the outer peripheral portion of the vortex chamber to squeeze the transport fluid to obtain steep diode characteristics,
A pump device having a self-control function, characterized in that it has a function of constantly controlling the discharge pressure of the pump to be substantially constant against fluctuations in the pump load. 2. The backflow conduit is arranged so that a backflow fluid flows in a tangential direction of an outer peripheral portion of the vortex chamber and the transport fluid flows in a substantially radial direction of the vortex chamber and collides with the backflow fluid. 2. The pump device with a self-control function according to claim 1, wherein an angle formed by the flow direction of the backflow fluid and the flow direction of the transport fluid is larger than 90 °.