JP2001295791A - Volute pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a volute pump capable of reducing in shaft vibration. SOLUTION: The volute pump accommodates an impeller 30 inside a volute casing 10 having a volute flow path 11, which is provided with a partition 13 separating the volute flow path 11 into two, 11-1 and 11-2, along the direction of the volute flow path 11 from a midpoint thereof. The volute flow path 11 and the volute flow path 11-1 are made asymmetrical from the center of rotation of the impeller 30 by providing a starting end of winding a1 of the partition 30 shifted by a predetermined angle α from a position 180 degree progressed from a starting end of winding a2 of the volute casing 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a centrifugal pump.

[0002]

2. Description of the Related Art Conventionally, some centrifugal pumps have a double volute structure as shown in FIG. That is, the spiral pump is configured by housing the impeller 100 inside a spiral casing 80 having a volute flow path 81. The volute flow channel 81 is provided with a partition wall 83 that divides the volute flow channel 81 into two (volute flow channels 81-1 and 81-2) along the direction of the volute flow channel 81 from the middle thereof.

Here, the winding start end a1 of the partition wall 83 is separated from the winding start end a2 of the spiral casing 80 by the impeller 100.
Is installed at a position of 180 ° around the rotation center O of
Thereby, the volute flow path 81 in the portion without the partition wall 83
And the inner volute channel 8 partitioned by the partition wall 83
1-1 is symmetrical with respect to the center O of the rotating shaft 101 of the impeller 100.

The flow area A of the throat portion 90 immediately before the winding start end a1 of the partition wall 83 of the volute flow path 81.
No. 2 is to make the flow rates of the throat portion 91 immediately before the winding start end a2 of the spiral casing 80 the same as that of the throat portion 91 so that the two flow rates are the same. Inefficiency). Volute channel 8
In the vicinity of the ends of 1-1 and 1-2, a diffuser section 85 for increasing the flow path area of both and reducing the flow velocity is provided, and the diffuser sections 8 of both volute flow paths 81-1 and 81-2 are provided.
By making the flow rates of the five portions the same, the merging can be performed smoothly.

Since the volute passage 81 without the partition wall 83 and the inner volute passage 81-1 partitioned by the partition wall 83 are formed symmetrically about the center of rotation O, the flow in the radial direction is reduced. The physical strength is balanced and mutually canceled. Therefore, the static fluid force applied to the impeller 100 by the fluid in each part in the spiral casing 80 is the impeller 1
The balance is achieved around the rotation axis 101 of 00, and the whole is almost canceled. Therefore, the bearing load of the central shaft 101 is reduced, and theoretically, only the weight of the impeller 100 is applied to the rotating shaft 101.

Here, the static fluid force refers to a force acting on the impeller 100 due to the fluid when the impeller 100 is driven in the spiral casing 80, that is, a force in a certain direction (the direction is changed randomly with time). Say no power). On the other hand, when the impeller 100 is driven in the spiral casing 80, a force in the random direction (a force that changes the direction randomly with time) applied to the impeller 100 by the fluid is referred to as a dynamic fluid force.

However, in practice, the static fluid force cannot be completely canceled, and a residual static fluid force remains. As a result, the relationship between the forces applied to the rotating shaft 101 is as shown in FIG. That is, FIG. 9 is a diagram showing vectors of various fluid forces applied to the impeller 100. As shown in the figure, the resultant force of the weight of the impeller 100 and the residual static fluid force is applied to the impeller 100 as the total static force, and at the same time, the dynamic fluid force is randomly set within the range of the dotted circle in the figure. Is added to

Accordingly, the force applied to the impeller 100 is larger in the dynamic fluid force than in the total static force, and the rotating shaft 101 of the impeller 100 is moved in a certain direction with respect to its bearing by the total static force. , And comes into random contact with the entire circumference of the bearing due to the dynamic fluid force. As a result, the dynamic force due to the whirling of the rotating shaft 101 of the impeller 100 is also applied to increase the shaft vibration. There was a problem that it would.

FIG. 10 is a graph showing the flow rate-efficiency characteristics of a centrifugal pump. As shown in the figure, the maximum efficiency of the centrifugal pump is the flow area A1, A2 of the throat portions 90, 91.
Is determined by the area (namely, the flow velocity). For this reason, in order not to lose the maximum efficiency of the pump, when there are a plurality of volute channels 81 and 81-1 as in the above-mentioned volute pump,
The flow area A1, A2 of the throat parts 90, 91 is set so that the flow velocity of each throat part 90, 91 becomes equal. That is, if the solid curve shown in FIG. 10 is the flow rate-efficiency characteristic of the two volute flow paths 81 and 81-1, as shown in FIG. It becomes a curve.

However, in recent years, there has been a demand for a centrifugal pump having a wider flow rate range with a certain efficiency or more even if the maximum efficiency is somewhat reduced, but the above-mentioned conventional centrifugal pump cannot satisfy this requirement. That is, in FIG. 11, the flow rate range of the pump exhibiting the efficiency of A% or more of the highest efficiency is as shown in the figure, but a wider flow rate range is required.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a centrifugal pump capable of reducing shaft vibration.

Another object of the present invention is to provide a centrifugal pump capable of exhibiting a certain degree of efficiency over a wide flow rate range.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a volute pump in which an impeller is housed inside a volute casing having a plurality of volute passages. The winding start end is set at an angle other than a uniform angle when viewed from the rotation center of the impeller. That is, the angle is set at 180 ° ± α ° when there are two volute channels, and at 120 ° ± α ° when there are three volute channels.

Here, when there are two volute channels, the following is performed. That is, a centrifugal pump in which an impeller is housed inside a volute casing having a volute flow path, and a partition wall for separating the volute flow path into two along the direction of the volute flow path is provided in the volute flow path. In the above, the winding start end of the volute flow path in the portion without the partition wall and the winding start end of the inner volute flow path partitioned by the partition wall are asymmetrically viewed from the rotation center of the impeller.

Further, the present invention is characterized in that, in a centrifugal pump having a plurality of volute flow paths, the flow area of each throat section is set so that the flow velocity in the throat section of each volute flow path is different.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic side sectional view showing a centrifugal pump according to one embodiment of the present invention. As shown in FIG. 1, the spiral pump is configured by housing an impeller 30 inside a spiral casing 10 having a volute flow channel 11. The volute flow channel 11 is provided with a partition wall 13 that divides the volute flow channel 11 into two (volute flow channels 11-1 and 11-2) along the direction of the volute flow channel 11 from the middle thereof.

In this embodiment, the winding start end of the partition wall 13 (ie, the winding start end of the volute flow path 11-1) a1 is changed to the winding start end of the spiral casing 10 (ie, the winding start end of the volute flow path 11). It is installed at a position of 180 ° + α ° (a position other than a uniform angle) around the rotation center O of the impeller 30 from the (starting end) a2. That is, the volute channel 11 in the portion without the partition 13 and the inner volute channel 11-1 partitioned by the partition 13 are configured to be slightly asymmetric with respect to the center O of the rotation shaft 31 of the impeller 30. I have.

At this time, the flow path area A of the throat section 20 immediately before the winding start end a1 of the partition wall 13 of the volute flow path 11 is set.
2 is a flow area A of the throat portion 21 of the volute flow path 11-1 immediately before the winding start end a2 of the spiral casing 10.
A1 = (180 + α) · (A1 + A2) / (360) A1 = (180−α) · (A1 + A2) / (360) It is necessary to keep the efficiency of the system good. Further, the flow rates of the diffuser portions 15 of the two volute flow paths 11-1 and 11-2 are made the same so that the merging can be performed smoothly.

Since the volute flow path 11 and the volute flow path 11-1 are configured asymmetrically in this manner, the static fluid force applied to the impeller 30 by the fluid in each part in the spiral casing 10 is reduced by the rotation axis of the impeller 30. Unbalanced around 31 generates residual static fluid force.

In other words, in this embodiment, the residual static fluid force is positively left, so that the relationship between the force applied to the impeller 30 and the weight of the impeller 10 is shown in FIG. (Total static force) is made larger than the dynamic fluid force. With this configuration, the rotating shaft 31 can be pressed in a fixed direction against the bearing by the total static force, and as a result, the rotating shaft 31
Does not swing around the entire circumference, and the shaft vibration decreases.

In addition, compared to a single volute pump without a partition, a double volute pump with a partition originally has a small static fluid force, so that the bearing load does not increase more than necessary and the increase in bearing capacity is small. Can be suppressed.

FIG. 3 is a schematic sectional side view showing a centrifugal pump according to another embodiment of the present invention. The difference between the centrifugal pump shown in FIG. 1 and the centrifugal pump shown in FIG.
The only difference is that the winding start end a1 of the partition wall 13 is located at a position of 180 ° -α ° about the rotation center O of the impeller 30 from the winding start end a2 of the spiral casing 10. Even with such a configuration, the part of the volute flow path 11 without the partition 13 and the inner volute flow path 11-1 partitioned by the partition 13 are slightly asymmetric with respect to the center O of the rotating shaft 31 of the impeller 30. It can be configured to be.

At this time, the flow path area A of the throat section 20 immediately before the winding start end a1 of the partition wall 13 of the volute flow path 11 is obtained.
2 is a flow area A of the throat portion 21 of the volute flow path 11-1 immediately before the winding start end a2 of the spiral casing 10.
A1 = (180−α) · (A1 + A2) / (360) A1 = (180 + α) · (A1 + A2) / (360) It is necessary to keep the efficiency of the system good. Further, the flow rates of the diffuser portions 15 of the two volute flow paths 11-1 and 11-2 are made the same so that the merging can be performed smoothly.

If the volute flow path 11 and the volute flow path 11-1 are configured to be asymmetrical in this manner, the fluid in each part in the spiral casing 10 is applied to the impeller 30 by the static fluid force as described above. The residual static fluid force can be positively generated without being balanced around the rotating shaft 31 of the vehicle 30, and as a result, the relationship between the forces applied to the rotating shaft 31 becomes as shown in FIG. The force obtained by adding the residual static fluid force and the weight of the impeller 30 (total static force) can be made larger than the dynamic fluid force, and the rotating shaft 31 is pressed against the bearing in a certain direction by the total static force. As a result, the rotating shaft 31 does not swing around the entire circumference, and the shaft vibration is reduced.

FIG. 5 is a schematic sectional side view showing a centrifugal pump according to another embodiment of the present invention. 8, the winding start end a1 of the volute flow path 11-1 and the volute flow path 1 are similar to the conventional example shown in FIG.
Although the winding start end part a2 is set at a position 180 ° around the rotation center O of the impeller 30, that is, at a symmetrical position, the throat of each of the volute flow paths 11, 11-1 is set. By making the flow passage areas A2 and A1 of the portions 20 and 21 different, the flow velocities are made different. In addition, the diffuser part 15 of both the volute flow paths 11-1 and 11-2.
Is the same as in the above embodiments in that the flow speed of the portion is made the same and the merge is smooth.

With this configuration, as shown in FIG.
The respective pump efficiencies (indicated by dotted lines) in the respective volute flow paths 11 and 11-1 are different, and the total efficiency (indicated by solid lines) obtained by dividing the two by 2 is slightly lower in the maximum efficiency, but to some extent The flow rate range where the efficiency is higher than the efficiency (for example, A% of the maximum efficiency) is widened.

In this embodiment, since the flow rates of the two throat portions 20 and 21 located at symmetrical positions are different, the pressure distribution of the two volute flow paths 11 and 11-1 is changed to change the pressure balance. As shown in FIG. 6, the residual static fluid force increases, and a force obtained by adding the residual static fluid force and the weight of the impeller 30 (total static force), similarly to the above embodiments.
Can be larger than the dynamic fluid force, and the axial vibration of the rotating shaft 31 can be reduced.

This embodiment may be applied to an embodiment in which the positions of the throat portions 20 and 21 are not symmetrical as shown in FIGS. In the above embodiment, the flow path area A2 of the throat section 20 is changed to the flow path area A2 of the throat section 21.
1 and the flow velocity is made different from each other. On the contrary, the flow area A2 of the throat section 20 is made larger than the flow area A1 of the throat section 21 so that the flow velocity becomes different. May be different.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims and the technical idea described in the specification and the drawings. Is possible. It should be noted that any shape or material not directly described in the specification and the drawings is within the scope of the technical idea of the present invention as long as the effects and effects of the present invention are exhibited. For example, in the above embodiment, the rotation shaft 31
Is installed on the horizontal axis, so that the impeller 30
However, if the rotating shaft 31 is set to be the vertical axis, the weight of the impeller 30 does not need to be added to the total static force, in which case the residual static fluid force is the same as the total static force. The volute flow path may be made asymmetric so that the total static force is greater than the dynamic fluid force.

[0030]

As described above in detail, according to the present invention, since the volute flow path is asymmetric and the residual static fluid force is actively generated and used, the total static force is reduced. It can be larger than the dynamic fluid force, and the rotating shaft can be pressed in a certain direction against the bearing by the total static force,
As a result, there is an excellent effect that the rotating shaft does not swing around the entire circumference and the shaft vibration can be reduced.

Further, according to the present invention, since the flow areas of the throat portions of the respective volute flow paths are set so that the flow speeds thereof are different, it is possible to provide a centrifugal pump capable of exhibiting a certain degree of efficiency over a wide flow rate range.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship between forces applied to a rotating shaft 31;

FIG. 3 is a schematic sectional side view showing a centrifugal pump according to another embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between forces applied to a rotating shaft 31;

FIG. 5 is a schematic sectional side view showing a centrifugal pump according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship between forces applied to a rotating shaft 31;

FIG. 7 is a view showing a flow rate-efficiency characteristic of the centrifugal pump shown in FIG. 5;

FIG. 8 is a schematic side sectional view showing a conventional centrifugal pump.

FIG. 9 is a diagram showing a relationship between forces applied to a rotating shaft 101.

FIG. 10 is a diagram showing a flow rate-efficiency characteristic of a centrifugal pump.

FIG. 11 is a diagram showing a flow rate-efficiency characteristic of a conventional centrifugal pump.

[Explanation of symbols]

 Reference Signs List 10 spiral casing 11, 11-1, 11-2 volute flow path a1 winding start end of partition 13 a2 winding start end of spiral casing 13 partition 15 diffuser 30 impeller 31 rotating shaft

Claims (3)

[Claims] 1. A spiral pump in which an impeller is housed inside a spiral casing having a plurality of volute flow paths, wherein winding start ends of the plurality of volute flow paths are uniform when viewed from the rotation center of the impeller. A centrifugal pump characterized by being installed at an angle other than the angle. 2. An impeller is housed inside a spiral casing having a volute flow path, and a partition wall is provided in the volute flow path to separate the volute flow path into two along the direction of the volute flow path. In the centrifugal pump, the winding start end of the volute flow path in the portion without the partition and the winding start end of the inner volute flow path partitioned by the partition are asymmetrical as viewed from the rotation center of the impeller. Features a centrifugal pump. 3. A centrifugal pump having a plurality of volute flow paths, wherein the flow area of each throat section is set such that the flow velocity in the throat section of each volute flow path is different.