JPH06101688A - Discharge characteristic controlling type centrifugal pump - Google Patents

Abstract

PURPOSE:To simplify the construction of a controller in a discharge characteristic controlling type centrifugal pump. CONSTITUTION:A disk 12 opposed through a clearance to the open side end edge of a blade 10 of an impeller 5 is fixed to a spindle 15 coaxial with a impeller main shaft 3. A piston 9 is connected to the spindle 15 to be axially moved together with the spindle. The piston 9 is axially movably fitted in a cylinder 8 so that a variable pressure chamber 20 for pressing the piston 9 against the axial thrust of the disk 12 is formed. An inlet of the variable pressure chamber 20 is connected to a pump discharge section through a pressure responsive valve 28 adjusting the opening to the larger side in response to the increase of the pump discharge pressure to introduce the discharge water into the variable pressure chamber 20, and an outlet of the variable pressure chamber 20 is connected to a pump suction section through a throttle 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises, in a pump casing, an impeller whose one side in the axial direction is open, and a disk which is opposed to the open end with an axial gap. By moving the in the axial direction to adjust the gap,
The present invention relates to a discharge characteristic control type centrifugal pump that controls discharge characteristics.

[0002]

2. Description of the Related Art A centrifugal pump employing this type of control system is disclosed in Japanese Utility Model Laid-Open No. 1-91095. FIG. 4 shows a simplified example of the structure of the above-mentioned prior art. It has a large number of centrifugal blades 104, and one end side in the axial direction, for example, an open impeller 101 whose front end is open, and the above-mentioned blades 104. And a disc 102 facing each other with a gap S in the axial direction therebetween. The spindle 102 to which the disc 103 is fixed is arranged concentrically with the main shaft 106 of the impeller 101 and is movably pumped in the axial direction. It is supported by the casing and is connected to the piston 105 of the servo cylinder 109. The piston 105 divides the inside of the cylinder 109 into two chambers, a first pressure chamber 107 and a second pressure chamber 108.
The inlet of the first pressure chamber 107 is connected to the pump discharge port 111 via the pressure response valve 110, and the second pressure chamber 10 on the opposite side is connected.
The inlet of No. 8 is connected to the discharge port 111 via the throttle 112 to introduce the discharge pressure. The outlets of both chambers 107 and 108 are throttles 120 and 121, respectively.
Is connected to the suction port of the pump, for example.

The pressure responsive valve 110 is located on the discharge port 111 side.
When the secondary pressure becomes higher, the secondary pressure on the first pressure chamber 107 side decreases, and conversely, when the primary pressure becomes lower, the secondary pressure increases.

When the discharge pressure rises and the pressure in the second pressure chamber 108 rises, the secondary pressure of the pressure responsive valve 110 enters.
The pressure in the pressure chamber 107 greatly drops, and both pressure chambers 107,
Due to the difference between the pressure difference between 108 and the thrust of the disc 103 in the axial direction, the piston 105 advances and the gap S becomes large, whereby the discharge pressure decreases, and the piston 105 stays at the set value.
When the discharge pressure decreases, the first pressure chamber 10
Since 7 is larger than the initially set value, the first pressure chamber 107
Of pressure and the thrust of the disk 103, and the second pressure chamber 10
8 causes the piston 105 to retreat with a large thrust to reduce the gap S, thereby increasing the discharge pressure and stopping at the set discharge pressure. In addition, the above-mentioned actual Kaihei 1-91
In addition to the above-described embodiment, No. 095 shows that, as the pressure responsive valve 110, when the primary pressure on the side of the discharge port 111 becomes high, the secondary pressure also rises, and conversely, when the primary pressure becomes low, 2 There is also disclosed a structure in which a structure having a lower secondary pressure is connected to the second pressure chamber side 108 in FIG.

[0005]

In the conventional structure as described above, two pressure chambers must be formed in the cylinder without fail, and a throttle is required for each pressure chamber. A pipe for supplying the discharge pressure to the pressure chamber is required.

An object of the present invention is to simplify the structure by allowing the second pressure chamber to be substantially eliminated.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to an impeller whose axial one side is open and an axial gap between the open end of the impeller and the pump casing. In a discharge characteristic control type centrifugal pump in which the discharge characteristics are controlled by moving the disks in the axial direction and adjusting the above-mentioned gap, the disk is a spindle coaxial with the impeller main shaft. The spindle is fixed to the pump casing so as to be movable in the axial direction, and a piston is coupled to the spindle so as to be movable in the axial direction together with the spindle, and the piston is fitted in the cylinder so as to be movable in the axial direction. This creates a fluctuating pressure chamber that pressurizes the piston in a direction that opposes the axial thrust of the disc, and the opening of the fluctuating pressure chamber is adjusted to the large side as the pump discharge pressure increases. Change the discharge water When the discharge pressure is higher than the set value of the pressure responsive valve, it is connected to the pump discharge part via the pressure responsive valve introduced into the pressure chamber, and the outlet of the fluctuating pressure chamber is connected to the pump suction part via the throttle. The pressure of the pressure chamber overcomes the thrust to move the disc to the gap opening side, and when the discharge pressure is lower than the set value, the thrust of the disc moves to the gap closing side, and the discharge pressure is set to the set value. I try to keep it.

[0008]

[Operation] When the discharge pressure of the pump becomes smaller than the set value,
The opening of the pressure-responsive valve decreases, the pressure in the fluctuating pressure chamber decreases, and the axial thrust toward the gap closing side of the disc overcomes the pressure in the fluctuating pressure chamber, moving the spindle and disc to the gap closing side. However, this causes the discharge pressure of the pump to rise.

When the discharge pressure of the pump becomes larger than the set value, the opening of the pressure responsive valve increases and the pressure of the fluctuating pressure chamber increases, so that the pressure of the fluctuating pressure chamber overcomes the axial thrust of the disc. , The spindle and the disk are moved to the gap opening side, which reduces the discharge pressure of the pump.

When the pump discharge pressure is at the set value, the pressure in the fluctuating pressure chamber and the thrust of the disc are in equilibrium, the piston does not move, the spindle and the disc are maintained at the same axial position, and the gap is It does not change and the pump discharge pressure is maintained at or near the set value.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a discharge characteristic control type centrifugal pump to which the present invention is applied. In FIG. 1, a bracket 2 is connected to the axial rear of a pump casing 1, and a main shaft 3 rotates on the bracket 2. It is supported freely and immovably in the axial direction. An impeller 5 is fixed to an inner portion of the casing 1 at the front end of the main shaft 3, and an electric motor 7 is provided at the rear end of the main shaft 3.
Is linked to.

The impeller 5 has a large number of centrifugal blades 10 fixed and is open toward the front. A disk 12 for the front wall faces the front edge of the blade 10 with a gap S therebetween. It is arranged.

The disk 12 is integrally fixed to the spindle 15 via a mounting boss portion 14 having a water absorption passage 13, and the water absorption passage 13 has a suction port 17 and a front inner space of the impeller 5. Communicating with the department. The spindle 15 is arranged coaxially with the main shaft 3 and is supported by the casing 1 via a bearing metal 18 and the like so as to be movable in the axial direction.

A cylinder 8 is provided at the front end of the pump casing 1.
Is fixed to the cylinder 8, a piston 9 is fitted in the cylinder 8 so as to be movable in the front-rear direction, and a front end portion of the spindle 15 is projected.
They are connected so as to move integrally in the axial direction.

The cylinder 8 is divided into a rear side variable pressure chamber 20 and a front side low pressure chamber 21 by fitting a piston 9 slidably in the axial direction, and an inlet 23 of the variable pressure chamber 20.
Is connected to the discharge port 19 of the pump via a pressure passage (pipe) 29 having a pressure responsive valve 28, and the pump discharge water is decompressed and introduced into the variable pressure chamber 20. The outlet 24 of the fluctuating pressure chamber 20 passes through an outlet passage (pipe) 27 having a throttle 25, and a low pressure part of the pump (for example, the suction port 17).
Connected to. The low-pressure chamber 21 on the front side is opened under atmospheric pressure through the opening 22 or, as shown by a chain line, the pipe 2
7 to the pump suction port 17.

In FIG. 2, the disc 12 is configured such that, during operation, a thrust force is generated in the direction of closing the gap S, that is, in the axial direction to the rear, due to the difference in water pressure between the front and rear of the disc 12. . In addition, an annular portion 26 is formed on the front surface of the disk 12 against such a thrust, so that the large thrust (thrust force) can be reduced and adjusted.

In FIG. 3 showing the details of the pressure responsive valve 28, the case 30 of the pressure responsive valve 28 is the upper case portion 3
2 and the lower case portion 31, and the outer peripheral edge portion of the diaphragm 33 is held at the joint portion between the two case portions 31 and 32. The diaphragm 33 is positioned substantially at right angles to the center line 0-0 of the case 30, and
The inside of 0 is divided into upper and lower parts.

The lower case portion 31 is formed with an inlet 35 connected to the upstream side portion of the pressure passage 29 and an outlet 36 connected to the downstream side portion. The inlet 35 and the outlet 36 are inside the lower case portion 31. Communicates with the chamber on the inlet side and the chamber on the outlet side. These chambers are separated by a partition wall 37 provided inside the lower case portion 31, and communicate with each other only through a valve port 38 formed in the partition wall 37.

The valve port 38 is provided concentrically with the center line 0-0 of the case 30, and the upper end of the valve rod 40 has the diaphragm 3 at its upper end.
It is directly connected to the support plate 41 fixed to the central portion of the lower surface of the plate 3.
The lower end of the valve rod 40 is connected to the valve body 42.

The valve body 42 is provided concentrically with the valve port 38 and at a position on the inlet 35 side. A valve seat 46 is formed on the upper surface of the partition wall 37 around the valve opening 38.
A spring bearing plate 50 is fixed to the upper surface of the central portion of the diaphragm 33.

The spring receiving plate 50 has a compression coil spring 51.
The bottom edge of is seated. The spring 51 has a case center line 0-
It extends concentrically with 0, and its upper end is seated on the spring receiver 52. The spring receiver 52 has a projection on the outer periphery thereof fitted in a groove provided on the cylindrical inner surface of the upper case portion 32 in a non-rotatable manner and slidable in a direction parallel to the center line 0-0. . A screw hole into which the screw shaft 53 is screwed is formed in the center of the spring receiver 52. The upper end of the screw shaft 53 projects upward from the hole of the upper case portion 32, and a handle 55 for rotating operation is attached to the projecting end. A stopper 56 is attached to the screw shaft 53 inside the upper case portion 32 and above the spring bearing 52.

According to the above structure, when the water pressure supplied from the inlet 35 decreases, the diaphragm 33 is pushed by the spring 51 and moves downward, and accordingly, the valve rod 40 and the valve body 4 are moved.
2 moves downward, and the opening degree of the valve opening 38 decreases. That is, the pressure responsive valve 28 is in the closed state or the opening degree reduced state.

When the water pressure supplied from the inlet 35 increases, the supplied water pressure pushes up the diaphragm 33 against the elastic force of the spring 51. Thereby, the valve body 42
Is pushed up, and the opening degree of the valve opening 38 increases.

When the water pressure supplied from the inlet 35 is a predetermined set value, as is apparent from the above description, the valve body 42 is
The valve opening 38 is opened in a state where the opening degree is reduced, and the pressure responsive valve 28 is in a half open state.

Of course, by operating the handle 55 to change the compression state of the spring 51, the movement characteristics of the diaphragm 33 with respect to the supply water pressure, that is, the pressure responsive valve 2
It is possible to adjust the opening / closing characteristics of No. 8 and adjust the set value according to various specifications.

The specific specifications of each of the above parts are set so that each part operates as follows in relation to the above operation of the pressure responsive valve 28. When the discharge pressure of the pump decreases to a value smaller than the set value, the opening degree of the pressure responsive valve 28 decreases, and the pressure supply to the fluctuating pressure chamber 20 is stopped or nearly stopped. In this state, the pressure in the fluctuating pressure chamber 20 drops, so that the thrust force of the disk 12 in the axial rearward direction overcomes the pressure in the fluctuating pressure chamber 20, and the piston 9 and the spindle 1
5 and the disk 12 are moved rearward to narrow the gap S. As a result, the discharge pressure of the pump rises.

When the discharge pressure of the pump increases to a value larger than the set value, the opening degree of the pressure responsive valve 28 increases to the open state or a state close to it, and the variable pressure chamber 20 receives the discharge pressure or the discharge pressure. Near pressure is supplied. In this state, the pressure in the fluctuating pressure chamber 20 increases, so the fluctuating pressure chamber 20
Pressure overcomes the rearward thrust of the disc 12 to move the piston 9, the spindle 15 and the disc 12 forward, thereby widening the gap S. This reduces the discharge pressure of the pump.

When the pump discharge pressure is at the set value, the pressure responsive valve 28 is in a half-open state, and a relatively low pressure is supplied to the variable pressure chamber 20. In this state, the forward pressure of the variable pressure chamber 20 and the backward thrust of the disk 12 are balanced, and the piston 9 does not move. Therefore, the spindle 15 and the disk 12 are also maintained at the same axial positions, the gap S does not change, and the pump discharge pressure is maintained at a set value or a value in the vicinity thereof. As described above, the pump discharge pressure is always maintained at or near the set value.

[0029]

As described above, according to the invention of the present application, (1) Fluctuations using the thrust force in the axial direction of the disc caused by the water pressure difference generated before and after the disc during operation and the pressure of the pump discharge water. Since the axial position of the disc is adjusted by balancing with the pressure of the pressure chamber, the pressure difference between the two chambers in the cylinder and the three thrust forces in the axial direction of the disc, as in the past, are used. Compared to the structure that adjusts the gap, the structure of the chamber on the side opposite to the fluctuating pressure chamber can be opened under atmospheric pressure to be a very simple structure, or it can be abolished ultimately. Will be even easier.

(2) Since the chamber on the side opposite to the fluctuating pressure chamber can be simplified or omitted, the throttles and pipes associated therewith can also be omitted, and the structure can be further simplified.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a discharge characteristic control type centrifugal pump to which the present invention is applied.

FIG. 2 is an enlarged view of a blade portion in FIG.

FIG. 3 is an enlarged vertical cross-sectional view of the pressure responsive valve.

FIG. 4 is a simplified vertical sectional view of a conventional example.

[Explanation of symbols]

 1 Pump Casing 5 Open Type Impeller 8 Cylinder 9 Piston 12 Disc 15 Spindle 17 Suction Port (Suction Port) 19 Discharge Port (Discharge Port) 20 Variable Pressure Chamber 25 Throttle 28 Pressure Response Valve

Claims (1)

[Claims] 1. A pump casing is provided with an impeller whose one side in the axial direction is open, and a disc facing the open end with an axial gap, and the disc is moved in the axial direction. In the discharge characteristic control type centrifugal pump for controlling the discharge characteristic by adjusting the gap, the disc is fixed to the spindle coaxial with the impeller main shaft, and the spindle is movable in the axial direction. The piston is connected to the spindle so as to be movable in the axial direction together with the spindle, and the piston is fitted in the cylinder so as to be movable in the axial direction. A variable pressure chamber that pressurizes the piston is formed at the inlet of the variable pressure chamber, and the opening of the variable pressure chamber is adjusted to the large side according to the increase of the pump discharge pressure, and a pressure response valve that introduces discharge water into the variable pressure chamber is provided. Connected to the pump discharge part Then, connect the outlet of the fluctuating pressure chamber to the pump suction part through a throttle, and when the discharge pressure is higher than the set value of the pressure-responsive valve, the pressure of the fluctuating pressure chamber overcomes the thrust and moves the disc to the gap opening side. When the discharge pressure is lower than the set value, it is configured to move to the gap closing side by the thrust of the disc, and the discharge pressure is maintained at the set value. Centrifugal pump.