JP2023096418A - centrifugal pump - Google Patents

Abstract

To provide a centrifugal pump in which the efficiency of the pump is hard to decrease even when a dimension of a discharge port and a dimension of a connection destination are different.SOLUTION: A centrifugal pump 1 includes a housing 2 and an impeller 3, wherein the housing 2 has a main body portion 4 defining a space for housing the impeller 3 and a nozzle portion 5 extending from the main body portion 4, and a flow channel 6 extends across the main body portion 4 and the nozzle portion 5. A partition wall 7 is disposed on at least the nozzle portion 5, and the flow channel 6 is divided into a first flow channel 61 on the impeller 3 side and a second flow channel 62 on an inner wall side of the housing 2 by the partition wall 7. A cross-sectional area of the nozzle portion 5 at a distal end 51 from the main body portion 4 of the nozzle portion 5 is larger than a cross-sectional area of the nozzle portion 5 at a proximal end 52 connected to the main body portion 4, and an enlarged part 71 where a width of the partition wall 7 on a cross-section passing through a center axis of the nozzle portion 5 is larger than a width at the proximal end 52, is disposed on at least a part of the partition wall 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to centrifugal pumps.

Centrifugal pumps are widely used as one type of pump that urges fluid. The centrifugal pump includes a housing and an impeller housed in the housing, and the fluid urged radially outward by the centrifugal force of the rotating impeller flows along the inner wall of the housing to the discharge port. It is configured to be guided to

JP 2017-44197 A JP 2008-8154 A JP 2014-214741 A

Since centrifugal pumps are used in a wide variety of facilities, there are also a wide variety of sizes of pipes to which discharge ports are to be connected. On the other hand, there have been cases where the dimensions of the ideal discharge port of the pump, which is required from the viewpoint of efficient supply of the centrifugal pump, do not match the dimensions of the piping to which it should be connected. In such a case, the pump and the connection destination are connected via an adjustment nozzle portion for adjusting the pipe diameter, and a vortex is generated by the change in the cross-sectional area of the flow path in the adjustment nozzle portion. , which could reduce the efficiency of the pump.

Therefore, there is a demand for a centrifugal pump in which the efficiency of the pump does not easily decrease even when the ideal size of the discharge port differs from the size of the connection destination.

A centrifugal pump according to the present invention comprises a housing and an impeller housed in the housing,
The housing has a body portion defining a space for housing the impeller, a nozzle portion extending from the body portion, and a spiral in which a flow path extends across the body portion and the nozzle portion. In the pump, a partition wall is provided in at least the nozzle portion inside the housing, and the flow path is divided into a first flow path on the impeller side and a second flow path on the inner wall side of the housing by the partition wall. and a cross-sectional area of the nozzle portion at a distal end of the nozzle portion from the body portion is larger than a cross-sectional area of the nozzle portion at a proximal end connected to the body portion. , at least a portion of a portion of the partition wall provided in the nozzle portion has an enlarged portion in which the width of the partition wall in an arbitrary cross section passing through the central axis of the nozzle portion is larger than the width at the proximal end. is provided.

In this configuration, the diameter of the nozzle portion is expanded from the proximal end on the main body side to the distal end on the connection destination side to achieve size matching with the connection destination, and at the same time, the partition wall is partially enlarged. This prevents the cross-sectional area of the flow path from sharply increasing as the diameter of the nozzle portion increases. As a result, even if the dimensions of the discharge port and the dimensions of the connection destination are different, the efficiency of the pump is less likely to decrease.

Preferred embodiments of the present invention are described below. However, the scope of the present invention is not limited by the preferred embodiments described below.

As one aspect of the centrifugal pump according to the present invention, the partition wall extends to the vicinity of the distal end of the nozzle part, and the cross-sectional area of the partition wall in the vicinity of the distal end is It is preferably smaller than the maximum cross-sectional area of the partition wall in the enlarged portion.

According to this configuration, it is possible to further prevent the generation of vortices in the nozzle section.

As one aspect of the centrifugal pump according to the present invention, among the enlarged portions, the maximum portion in which the cross-sectional area of the partition wall has the maximum value is located closer to the distal end than the center between the proximal end and the distal end. is preferably provided on the side of the

According to this configuration, it is possible to further prevent the generation of vortices in the nozzle section.

As one aspect of the centrifugal pump according to the present invention, it is preferable that the cross-sectional area of the nozzle portion monotonically increases from the proximal end to the distal end.

According to this configuration, it is possible to further prevent the generation of vortices in the nozzle section.

As one aspect of the centrifugal pump according to the present invention, it is preferable that both the cross-sectional area of the first flow path and the cross-sectional area of the second flow path monotonously increase in the nozzle portion.

According to this configuration, it is possible to further prevent the generation of vortices in the nozzle section.

As one aspect of the centrifugal pump according to the present invention, it is preferable that the partition wall is provided over the main body portion and the nozzle portion.

According to this configuration, in a so-called double volute pump, it is possible to prevent the generation of vortices in the nozzle portion.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

1 is a cross-sectional view of a centrifugal pump according to an embodiment; FIG. It is a cross-sectional view of a nozzle portion of a centrifugal pump according to a first modification. It is a cross-sectional view of a nozzle portion of a centrifugal pump according to a second modification. It is a cross-sectional view of a nozzle portion of a centrifugal pump according to a third modification. It is a cross-sectional view of a nozzle portion of a centrifugal pump according to a fourth modification. FIG. 11 is a cross-sectional view of a nozzle portion of a centrifugal pump according to a fifth modification; It is a sectional view of a centrifugal pump concerning a modification. It is a cross-sectional view of a nozzle portion of a centrifugal pump according to a comparative example.

An embodiment of a centrifugal pump according to the present invention will be described with reference to the drawings. An example in which the centrifugal pump according to the present invention is applied to a centrifugal pump 1 (hereinafter simply referred to as "pump 1") used for the purpose of urging water will be described below.

[Structure of centrifugal pump]
The pump 1 comprises a housing 2 and an impeller 3 housed in the housing 2 (Fig. 1). The components of the pump 1 are not only the housing 2 and the impeller 3, but also a motor for driving the impeller 3, for example. Description and illustration of other components of are omitted. Specifications commonly used in the art can be applied to these other components.

The housing 2 has a body portion 4 defining a space for housing the impeller 3 and a nozzle portion 5 extending from the body portion 4 . The body portion 4 has a substantially cylindrical shape, and the nozzle portion 5 extends in a tangential direction of the cylindrical shape. Generally, the operation of the pump 1 is such that the water sucked from the primary side of the pump 1 by the impeller 3 is urged radially outward of the impeller 3 and flows along the inner wall of the main body 4 to the nozzle portion 5 . It is guided and expelled from the distal end 51 of the nozzle portion 5 .

A flow path 6 extends across the body portion 4 and the nozzle portion 5 . Channel 6 serves to guide the fluid urged by impeller 3 to distal end 51 of nozzle portion 5 . Moreover, a partition wall 7 is provided inside the housing 2 across the main body portion 4 and the nozzle portion 5 . The flow path 6 is divided by the partition wall 7 into a first flow path 61 on the impeller side (diameter direction inner side) and a second flow path 62 on the inner wall side (radial direction outer side) of the housing 2 . Note that the first channel 61 is sometimes called a volute-side channel or the like in this field. Also, the second flow path 62 is sometimes called a bypass-side flow path or the like in this field.

The nozzle portion 5 has a distal end 51 that is an end on the far side from the body portion 4 and a proximal end 52 that is an end connected to the body portion 4 . The distal end 51 is a part that functions as a discharge port of the pump 1 and is normally connected to a structure (piping, equipment, etc.) connected to the secondary side of the pump 1 . Therefore, the cross-sectional area of the nozzle portion 5 at the distal end 51 is determined in consideration of the dimensions of the structure. In the pump 1 according to this embodiment, the cross-sectional area of the nozzle portion 5 at the distal end 51 is larger than the cross-sectional area of the nozzle portion 5 at the proximal end 52 . The term “cross-sectional area” in the description of the present embodiment refers to the cross-sectional area of a cross section perpendicular to the flow path 6 unless otherwise specified. In addition, the cross-sectional area of the nozzle portion 5 refers to the area of the region defined by the inner wall of the nozzle portion 5 in the cross section. is the sum of the cross-sectional areas of

In this embodiment, the cross-sectional area of the nozzle portion 5 monotonously increases from the proximal end 52 to the distal end 51 . More specifically, the nozzle portion 5 has a truncated conical shape that widens from the proximal end 52 to the distal end 51 . Reflecting this truncated cone shape, the outer wall of the nozzle portion 5 is drawn as a straight line expanding from the proximal end 52 toward the distal end 51 in the cross-sectional view of FIG.

The partition wall 7 is a member integrally provided over the main body portion 4 and the nozzle portion 5 . However, since the portion provided in the main body portion 4 and the portion provided in the nozzle portion 5 have different characteristics, both will be described below. A centrifugal pump having a partition wall 7 extending over the body portion 4 and the nozzle portion 5, like the pump 1 according to the present embodiment, may be referred to as a double volute pump.

The partition wall 7 in the body portion 4 generally extends along an arc having a common center with the body portion 4 and the impeller 3 . As a result, the flow paths 6 (the first flow path 61 and the second flow path 62 ) in the main body 4 are defined in an arc shape that shares the center with the impeller 3 . The cross-sectional area of the partition wall 7 in the body portion 4 is substantially constant. Note that "substantially constant" means that the cross-sectional area is constant at least in terms of design, and is not required to be constant including errors. Further, even if the cross-sectional area of the details differs from that of the main part due to deformation (such as rounding) that is usually applied in manufacturing the pump 1 as an industrial product, it falls within the category of "substantially constant".

The partition wall 7 in the nozzle portion 5 extends to the distal end 51 side. Unlike the partition wall 7 in the body portion 4, the cross-sectional area of the partition wall 7 in the nozzle portion 5 is not constant. The partition wall 7 in the nozzle portion 5 is provided with an enlarged portion 71 . The enlarged portion 71 is a portion where the width of the partition wall 7 in an arbitrary cross section passing through the central axis of the nozzle portion 5 is larger than the width at the proximal end 52 . Here, the central axis of the nozzle portion 5 is an axis connecting the center of the cross section of the nozzle portion 5 at the proximal end 52 and the center of the cross section of the nozzle portion 5 at the distal end 51 . Moreover, the width of the partition wall 7 in an arbitrary cross section passing through the central axis of the nozzle portion 5 is, for example, the vertical width of the portion representing the partition wall 7 in FIG. In addition, the largest portion 72 , which is the portion having the largest cross-sectional area of the enlarged portion 71 , is located closer to the distal end 51 than the center between the proximal end 52 and the distal end 51 .

The cross-sectional area of the partition wall 7 monotonously increases continuously from the proximal end 52 to the maximum portion 72 and monotonously decreases continuously from the maximum portion 72 to the distal end 51 . Since the maximum portion 72 is provided at a position closer to the distal end 51 than the proximal end 52, the absolute value of the increase rate of the cross-sectional area of the partition wall 7 from the proximal end 52 to the maximum portion 72 is It is smaller than the absolute value of the rate of increase of the cross-sectional area of the partition wall 7 from 72 to the distal end 51 (it becomes a negative value).

The rate of increase in the cross-sectional area of the partition wall 7 is the cross-sectional area index (dimensionless) obtained by dividing the cross-sectional area of the partition wall 7 by the cross-sectional area of the partition wall 7 at the proximal end 52 (tongue). , as a function of the distance index (dimensionless) of the distance from the proximal end 52 divided by the inner diameter at the distal end 51 of the nozzle portion 5 . If the absolute value of the increase rate of the cross-sectional area of the partition wall 7 is relatively large, the flow of water in the flow path 6 (the first flow path 61 and the second flow path 62) may be obstructed, leading to a loss of pump output. be. From this point of view, it is preferable that the increase rate of the cross-sectional area of the partition wall 7 is 0 or more and 15 or less in the region from the proximal end 52 to the maximum portion 72 . Moreover, in the region extending from the maximum portion 72 to the distal end 51, the increase rate of the cross-sectional area of the partition wall 7 is preferably -30 or more and 0 or less, more preferably -30 or more and -10 or less.

With the above-described configuration related to the cross-sectional area of the partition wall 7 and the above-described configuration related to the cross-sectional area of the nozzle portion 5, the cross-sectional area of the flow path 6 (the first flow path 61 and the second flow path 62) is It increases gently from the end 52 to the maximum portion 72 and steeply increases from the maximum portion 72 to the distal end 51 . Therefore, the cross-sectional area of the channel 6 monotonically increases from the proximal end 52 to the distal end 51, although the gradient of increase differs depending on the site. In the present embodiment, the shapes of the nozzle part 5 and the partition wall 7 are adjusted so that the cross-sectional area of the first channel 61 and the cross-sectional area of the second channel 62 are substantially the same in the range of the enlarged portion 71. It is

The body portion 4, the nozzle portion 5, and the partition wall 7, which are the substantial portions that constitute the housing 2, can be integrally manufactured by a known method such as casting. However, the method of manufacturing the housing 2 is not particularly limited.

[Modification]
Modified examples of the nozzle portion and the partition wall will be described below. In any of the modifications, as in the above embodiment, even if the dimensions of the discharge port and the dimensions of the connection destination are different, it is possible to realize a centrifugal pump in which the efficiency of the pump is less likely to decrease.

In the nozzle portion 5A according to the first modification shown in FIG. 2, the maximum portion 73 is formed in a shape that protrudes more on the first channel side than on the second channel side. Therefore, in this modification, the cross-sectional area of the second flow path is larger than the cross-sectional area of the first flow path in the nozzle portion 5A.

In the nozzle portion 5B according to the second modification shown in FIG. 3, the ratio of the enlarged portion 74 to the length of the nozzle portion 5B is smaller than that of the above embodiment. A maximum portion 75 is also provided at the distal end of the partition wall.

In the nozzle portion 5C according to the third modification shown in FIG. 4, the cross-sectional area of the maximum portion 76 is smaller than that of the above embodiment. Therefore, in this modified example, the rate of change of the cross-sectional area of the channel 6 in the region from the proximal end to the maximum portion 76 is greater than in the above embodiment.

In the nozzle part 5D according to the fourth modification shown in FIG. 5 and the nozzle part 5E according to the fifth modification shown in FIG. 6, the outer shape on the first channel side and the outer shape on the second channel side are asymmetrical. . Specifically, the outer shape of the nozzle portions 5D and 5E on the second flow path side is a truncated cone surface as in the above embodiment. On the other hand, on the first channel side of the nozzle parts 5D and 5E, there are provided a proximal end side region 53 that expands at a gentler slope than the second channel side, and a distal end side region 54 that expands sharply. ing. In the nozzle portion 5D, a surface 77 of the partition wall on the side of the first flow path is formed linearly, and in the nozzle portion 5E, a surface 78 on the side of the first flow path expands radially outward.

[Other embodiments]
Finally, another embodiment of the centrifugal pump according to the present invention will be described. It should be noted that the configurations disclosed in the respective embodiments below can also be applied in combination with configurations disclosed in other embodiments unless there is a contradiction.

In the above embodiment, the configuration in which the partition wall 7 extends to the vicinity of the distal end 51 has been described as an example. However, in the present invention, the partition wall may not extend to the vicinity of the distal end, and for example, the end of the partition wall may be provided in the middle of the nozzle portion. In addition, "extending to the vicinity of the distal end" means that the end of the partition wall is located at a position that can be identified with the distal end, but it does not require that it be completely the same. . For example, the end of the partition wall may be recessed from the distal end of the nozzle section no more than 15% of the inner diameter at the distal end of the nozzle section.

In the above-described embodiment, the configuration in which the partition wall 7 extends over the main body portion 4 and the nozzle portion 5 has been described as an example. However, in the centrifugal pump according to the present invention, it is sufficient that the partition wall is provided at least in the nozzle portion. For example, a centrifugal pump 1A (FIG. 7) in which the partition wall 7 is provided only in the nozzle portion 5 and not provided in the main body portion 4 can also be one aspect of the present invention. The centrifugal pump 1A is a so-called single volute pump.

In the above embodiment, the configuration in which the maximum portion 72 is provided closer to the distal end 51 than to the proximal end 52 has been described as an example. However, in the present invention, the maximum portion may be provided at a position closer to the proximal end.

In the above embodiment, the configuration in which the cross-sectional area of the nozzle portion 5 monotonously increases from the proximal end 52 to the distal end 51 has been described as an example. However, in the present invention, the change tendency of the cross-sectional area of the nozzle portion is not limited to monotonous increase.

In the above embodiment, the configuration in which the cross-sectional area of the flow path 6 monotonically increases from the proximal end 52 to the distal end 51 has been described as an example. However, in the present invention, the change tendency of the cross-sectional area of the flow path in the nozzle portion is not limited to monotonous increase.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are examples in all respects, and that the scope of the present invention is not limited by them. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the scope of the present invention. Therefore, other embodiments modified without departing from the gist of the present invention are naturally included in the scope of the present invention.

The invention is further illustrated by the following examples. However, the following examples do not limit the present invention.

The flow of water during operation of the centrifugal pumps (Examples 1 to 6) having the nozzle portions of each shape shown in FIGS. 1 to 6 was simulated by computational fluid dynamics. In each simulation, the cross-sectional area of the nozzle section at the proximal end was 25% of the cross-sectional area of the nozzle section at the distal end, and the diameter of the nozzle section at the distal end was 200 mm.

Further, as a comparative example, a simulation was performed under the same conditions for a centrifugal pump having a nozzle portion 8 having the shape shown in FIG. In the nozzle part 8 according to the comparative example, the partition wall 9 is not provided with an enlarged portion, and the cross-sectional area of the partition wall 9 is substantially constant from the proximal end to the distal end. Also in the simulation of the comparative example, the cross-sectional area of the nozzle portion at the proximal end was set to 25% of the cross-sectional area of the nozzle portion at the distal end, and the diameter of the nozzle portion at the distal end was set to 200 mm.

Based on the simulation results, the hydraulic efficiency values of Examples 1 to 6 and Comparative Example were calculated. In each example, the flow rate point for calculating the hydraulic efficiency value was the same, and the flow rate point was set to the larger water flow side than the maximum efficiency point flow rate of the pump. Table 1 shows the hydraulic efficiency values for each example. In all examples, higher hydraulic efficiency values were obtained than in the comparative example, indicating that the centrifugal pump according to the present invention has high efficiency.

Table 1: Hydraulic Efficiency Values for Examples and Comparisons

INDUSTRIAL APPLICABILITY The present invention can be used, for example, in centrifugal pumps.

Reference Signs List 1 : centrifugal pump 2 : housing 3 : impeller 4 : body portion 5 : nozzle portion 51 : distal end 52 : proximal end 6 : flow path 61 : first flow path 62 : second flow path 7 : partition wall 71 : Enlarged part

Claims (6)

A housing and an impeller housed in the housing,
The housing has a body portion defining a space for housing the impeller, a nozzle portion extending from the body portion, and a spiral in which a flow path extends across the body portion and the nozzle portion. a pump,
A partition wall is provided in at least the nozzle portion inside the housing,
The flow path is divided into a first flow path on the impeller side and a second flow path on the inner wall side of the housing by the partition wall,
a cross-sectional area of the nozzle portion at a distal end of the nozzle portion from the body portion is larger than a cross-sectional area of the nozzle portion at a proximal end connected to the body portion;
At least part of a portion of the partition wall provided in the nozzle portion has an enlarged portion in which the width of the partition wall in an arbitrary cross section passing through the central axis of the nozzle portion is larger than the width at the proximal end. Centrifugal pump provided. The partition wall extends to the vicinity of the distal end of the nozzle part, and the cross-sectional area of the partition wall in the vicinity of the distal end is the maximum value of the cross-sectional area of the partition wall in the enlarged portion. Centrifugal pump according to claim 1, which is smaller. 3. Among the enlarged portions, a maximum portion in which the cross-sectional area of the partition wall has a maximum value is provided closer to the distal end than a center between the proximal end and the distal end. A centrifugal pump as described in . The centrifugal pump according to any one of claims 1 to 3, wherein the cross-sectional area of the nozzle portion monotonically increases from the proximal end to the distal end. 5. The centrifugal pump according to claim 4, wherein both the cross-sectional area of the first flow path and the cross-sectional area of the second flow path monotonously increase in the nozzle portion. The centrifugal pump according to any one of claims 1 to 5, wherein the partition wall is provided across the main body portion and the nozzle portion.

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