JP6971662B2 - Impeller - Google Patents

Description

The present invention relates to an impeller used in a centrifugal pump or a mixed flow pump.

Conventionally, a pump that pumps a liquid to the secondary side has been known. Such a pump is known to include an impeller in which a plurality of blades are provided in a shroud (see, for example, Patent Document 1). Such an impeller has a plurality of blades between the front shroud and the back shroud, and is rotated by a connected rotating shaft to increase the pressure of the liquid in the pump casing and pump it to the secondary side.

Special Table No. 10-504621

Generally, inside the impeller, a pressure difference occurs between the back shroud and the front shroud, and a secondary flow is generated. Due to this secondary flow, the loss increases, which causes a decrease in pump efficiency, and the head characteristic curve showing the total head becomes a mountain shape. In the region of the mountain-shaped lift characteristic curve rising to the right, surging occurs and the region becomes unstable. In addition, this secondary flow reduces the amount of work and causes a decrease in head. Therefore, improvement of the secondary flow has been required so that the loss does not increase.

In addition, the impeller causes cavitation in a low flow rate region due to the difference in peripheral speed between the front shroud and the back shroud. As a measure against this cavitation, it is also known that the blades on the entrance side and the back shroud side are retracted from the center side of the back shroud to the outer peripheral edge side. However, this measure has a problem that the secondary flow increases.

Further, in the impeller of Patent Document 1, the secondary flow is suppressed by changing the blade angle, but there is also a problem that the angle change is complicated and it is difficult to design and manufacture.

Therefore, an object of the present invention is to provide an impeller that can improve the secondary flow, does not increase the secondary flow even if measures against cavitation in a low flow rate region are taken, and is easy to design and manufacture. And.

According to one aspect of the present invention, the impeller is configured in a disk shape and is erected on one main surface of a back shroud in which a rotation shaft can be inserted in the center and a back shroud in the axial direction of the back shroud. A plurality of blades having a cross- sectional shape parallel to the blade having a shape that bends at one turning point, and a front shroud having a suction port in the center and covering the plurality of blades and provided facing the back shroud. , wherein the vanes from the inlet side of the side edge of the blade to an intermediate portion toward the outer peripheral side of the back shroud, projects the previous SL-axis back shroud side in the direction away from the center of the back shroud curved Te, the table shroud side the axial direction, curved to protrude toward the center of the table shroud, of the inlet side of the outer surface of the front Symbol vanes, the surface of the radially outer side, the back shroud side The radius of curvature of the blade is the same as the radius of curvature on the front shroud side, and the bending point of the curved cross-sectional shape of the blade is from the intermediate position of the blade to the blade in the direction from the front shroud to the back shroud. It is provided in a range from the front shroud side to the position of 2/3, and the side edge on the inlet side of the blade is formed linearly in a plan view from the axial direction.

The present invention can provide an impeller capable of improving the secondary flow and taking measures against cavitation in a low flow rate region.

The plan view which shows the structure of the impeller which concerns on one Embodiment of this invention. A cross-sectional view showing the configuration of the impeller in an enlarged manner. A cross-sectional view showing the relationship between adjacent blades of the impeller. A cross-sectional view showing the relationship between adjacent blades of the impeller. A cross-sectional view showing the relationship between adjacent blades of the impeller. Explanatory drawing which shows the secondary flow in the blade of the impeller. A cross-sectional view showing the configuration of a conventional impeller in an enlarged manner. Explanatory drawing which shows the secondary flow in the blade of a conventional impeller. Explanatory drawing which compares and shows the performance of the impeller which concerns on one Embodiment and the conventional impeller. FIG. 3 is an enlarged cross-sectional view showing the configuration of an impeller according to another embodiment of the present invention.

Hereinafter, the impeller 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 9.
FIG. 1 is a plan view showing the configuration of the impeller 1 according to the embodiment of the present invention from the front shroud 13 side, FIG. 2 is the configuration of the impeller 1, and in particular, the cross-sectional shape of the blade 12 is shown in FIG. 1 II-II. Sectional views shown in line cross-section, FIGS. 3 to 5 are cross-sectional views showing the relationship with adjacent blades 12 in lines III-III, IV-IV and V-V in FIG. 1, and FIG. 6 is a blade. It is explanatory drawing which shows the analysis result of the flow of liquid in 12.

Further, FIG. 7 is a cross-sectional view showing the cross-sectional shape of the blade 112 of the conventional impeller 101, which compares the performance with the impeller 1 according to the embodiment, and FIG. 8 is an explanatory view showing the analysis result of the liquid flow in the blade 112. be. FIG. 9 is an explanatory diagram showing a comparison of the performances of the impeller 1 and the impeller 101.

As shown in FIGS. 1 to 5, the impeller 1 includes a back shroud 11, a plurality of blades 12, and a front shroud 13. In the present embodiment, the back shroud 11, the plurality of blades 12, and the front shroud 13 are integrally configured. When viewed in the posture of FIG. 1, the impeller 1 rotates counterclockwise.

In the impeller 1, the gap between the back shroud 11 and the front shroud 13 generated on the outer peripheral side of the impeller 1 constitutes a liquid discharge port, and the opening 13a provided in the center of the front shroud 13 constitutes a liquid suction port. The impeller 1 is used for a centrifugal pump or a mixed flow pump. For example, the impeller 1 is arranged in the pump casing of the pump and fixed to a rotating shaft connected to the motor. Such an impeller 1 sucks a liquid such as water from the suction port by rotating the rotating shaft by a motor, and increases the pressure of the liquid passing through the inside of the impeller 1 to discharge the liquid from the discharge port. Pump the liquid to.

The back shroud 11 is formed in the center of a disk-shaped base portion 21 and one of the main surfaces of the base portion 21, and the diameter is gradually reduced toward the tip thereof, and the center thereof opens. A trapezoidal protrusion 22 is provided. The opening of the protrusion 22 is inserted and fixed so that the axis of rotation penetrates.

A plurality of blades 12 are arranged between the back shroud 11 and the front shroud 13 at equal intervals in the circumferential direction. In this embodiment, six blades 12 are provided.

The blade 12 is arranged in a direction that is curved in the longitudinal direction and inclined with respect to the circumferential direction of the impeller 1 from the periphery of the protrusion 22 toward the outer peripheral edge of the base portion 21. As shown in FIG. 2, in the blade 12, the cross-sectional shape between the back shroud 11 and the front shroud 13 extends over the entire length in the longitudinal direction, or the side edge on the inlet side of the blade 12, in other words, the edge on the suction side. It has a shape that bends at at least one inflection point from to the outer peripheral side to the middle part.

For example, the blade 12 has at least one inflection in a direction in which at least a part thereof, for example, a range from the center side to the end of the impeller 1 on the suction port side intersects in the longitudinal direction of the blade 12. It has and curves. Further, in other words, the blade 12 is in the height direction, in other words, in the direction orthogonal to the straight line connecting the back shroud 11 and the front shroud 13 and the continuous portion, and the straight line of the blade 12 is located. It is configured to be curved at at least one turning point in the longitudinal direction of the blade 12 at the portion to be curved, in other words, in the direction orthogonal to the tangent line in the direction orthogonal to the straight line at the portion where the straight line of the blade 12 is located. Will be done. In the present embodiment, as shown in FIGS. 2 to 5, the blade 12 has a shape having one inflection point in the height direction from the side edge on the inlet side of the blade 12 to the middle portion toward the outer peripheral side. That is, the cross-sectional shape is integral-shaped, in other words, the cross-sectional shape is curved in a wavy shape so as to be uneven.

As a specific example, the position of the inflection point of the blade 12 having a curved cross-sectional shape is in the height direction of the blade 12, in other words, from the intermediate position between the back shroud 11 and the front shroud 13, and from the front shroud 13 side. It is provided in the range up to the 2/3 position (in the direction toward the back shroud 11).

As a specific example, the blade 12 projects toward the back shroud 11 side in the axial direction of the impeller 1 toward the outer peripheral edge side of the impeller 1, in other words, toward the outer peripheral edge side of the base portion 21 (direction away from the center of the back shroud 11). In the coaxial direction, it is curved so as to protrude toward the other side, that is, the front shroud 13 side, toward the center side of the impeller 1, in other words, the protrusion 22 side (the center side of the back shroud 11). Further, for example, in order to facilitate the design of the side edge on the inlet side, as shown in FIG. 1, the blade 12 is configured such that the side edge on the inlet side of the blade 12 is linear when viewed in a plan view. Will be done.

Further, the center angle θ of the inlet portion of the blade 12 is preferably 0 ° ≦ θ ≦ 70 °, and in the present embodiment, for example, θ = 35 °. Here, the center angle θ is the angle of the edge of the inlet portion of the blade 12 with respect to the center line connecting the center of the impeller 1 and the end portion of the blade 12 in contact with the front shroud 13. When θ> 0 °, the cross-sectional shape of the blade 12 is such that the back shroud 11 side is notched on the inlet side of the blade 12, but it is assumed that the inlet portion of the blade 12 is extended to θ = 0 °. In this case, the cross-sectional shape of the inlet portion of the blade 12 is not linear, but is configured to be curved at at least one inflection point.

Further, when the blade 12 has one inflection point, for example, as shown in FIG. 2, the radius of curvature R1 and R2 of the blade 12 near the entrance are set to the same radius of curvature. Further, R3 and R4 have a radius of curvature obtained by adding or subtracting the wall thickness of the blade 12 to R1 and R2, respectively. For example, in the blade 12 of the present embodiment, for example, the wall thickness of the blade 12 is set to be constant at 5 mm in the present embodiment, and is set to R1 = 30 mm, R2 = 30 mm, R3 = 35 mm, and R4 = 25 mm. ..

The front shroud 13 is formed in a disk shape and has an opening 13a forming a suction port of the impeller 1 in the center.

Next, FIGS. 2, 6 to 9 will be described with respect to the analysis results and performance of the liquid flow of the impeller 1 configured as described above and the conventional impeller 101 as a comparative example. In the performance curve of FIG. 9, the performance result of the impeller 1 according to the present embodiment is shown by a solid line, and the performance result of the impeller 101 of the comparative example is shown by a alternate long and short dash line.

The conventional impeller 101 is provided with measures to suppress the occurrence of cavitation in a low flow rate region, and the blades on the inlet side and the back shroud side are placed on the outer periphery from the center side of the back shroud. It is retracted to the veranda. Further, the conventional impeller 101 and the impeller 1 according to the present embodiment are configured to have the same dimensions except for the cross-sectional shape of the blade, and the specific speed Ns is 450 and the impeller outer diameter is 300 for comparison. bottom. The impeller 101 is provided with six blades 112 between the back shroud 11 and the front shroud 13, and the blades 112 are configured to have a linear cross-sectional shape as shown in FIG. 7.

First, as a result of fluid analysis of the impeller 1 according to the present embodiment, the flow of the liquid flows from the suction port side to the discharge port side of the impeller 1 along the longitudinal direction of the blade 12, as shown by an arrow in FIG. It became a flow extending in the radial direction.

On the other hand, as a result of fluid analysis of the conventional impeller 101, as shown by an arrow in FIG. 8, the liquid flow hits the front shroud 13 on the central side in the longitudinal direction of the blade 112, and then hits the discharge port. It became a flow to move toward. That is, the result is that a secondary flow of liquid is generated.

Further, comparing the performance of the impeller 1 of the present embodiment and the conventional impeller 101, as shown in the characteristic curve shown in FIG. 9, in the impeller 1 of the present embodiment, both the total head and the pump efficiency are conventional. As a result, the performance is improved as compared with the Impeller 101 of. In particular, as shown in the lift characteristic curve of the total head shown in FIG. 9, the impeller 1 resulted in an improvement in the total head even in the low flow rate region. That is, the impeller 1 has a result that the so-called right-up lift characteristic is reduced in the mountain-shaped lift characteristic curve as compared with the impeller 101. By adopting the configuration of the impeller 1 of the present embodiment, the secondary flow in which the liquid sucked from the suction port once hits the front shroud 13 like the conventional impeller 101 is reduced, and the liquid is the suction port of the impeller 1. It is considered that the flow is substantially linear from the to the discharge port, that is, the secondary flow generated by the conventional impeller 101 can be improved.

As a result, by adopting the configuration of the impeller 1 of the present embodiment, a higher total head can be obtained in the case of an impeller having the same outer diameter, and an impeller having a smaller outer diameter can be obtained in the case of the same total head. Therefore, a more compact pump can be provided.

Further, when the performance of the impeller 1 of the present embodiment and the conventional impeller 101 are compared, the result is that the impeller 1 of the present embodiment improves the total head and the pump efficiency in the high flow rate range. It is considered that this is because the configuration of the impeller 1 of the present embodiment can suppress the secondary flow and reduce the loss due to the secondary flow.

As described above, according to the impeller 1 according to the embodiment of the present invention, it is possible to improve the secondary flow by forming the cross-sectional shape of the blade 12 into a wavy shape by providing unevenness at least on the suction port side. Moreover, it is possible to take measures against cavitation in a low flow rate range. Further, the impeller 1 can be used for a centrifugal pump or a mixed flow pump. In other words, the impeller 1 can be used at a specific speed Ns of 100 to 800.

The present invention is not limited to the impeller 1 described in the above embodiment. For example, in the above-mentioned example, the impeller 1 has described the configuration having the front shroud 13, but for example, an inner surface having the same shape as the front shroud 13 is provided on the pump casing, and the inner surface of the pump casing is used instead of the front shroud 13. It may be configured as.

Further, in the above-mentioned example, the range of the curved portion of the blade 12 having at least one or more inflection points can be appropriately set. For example, the blade 12 is configured to be curved from the inlet to the exit of the impeller 1. It may be configured to be curved in a range of about 1/3 from the entrance. In the case of the blade 12 that curves within a predetermined range from the inlet, the radii of curvature R1 and R2 gradually increase in diameter as the distance from the center of the rotation axis increases, or the non-curved portion is formed linearly.

Further, the above-mentioned blade 12 has been described as a specific example having a configuration having one inflection point, but the present invention is not limited to this, and the blade 12 may have a configuration having a plurality of inflection points. That is, as long as the configuration can improve the secondary flow, the number of inflection points may be two or three or more. That is, if at least a part of the blade 12 has one or more inflection points between the back shroud 11 and the front shroud 13 and is curved to improve the secondary flow and improve the performance. , It can be appropriately set according to the outer diameter of the impeller 1, the number of blades, the shape, and the like.

Further, in the above-mentioned example, the configuration in which the impeller 1 has six blades 12 has been described, but the impeller 1 is not limited to this, and may be another number.

Further, in the above-mentioned example, the configuration in which all the blades 12 have a cross-sectional shape having at least one inflection point has been described, but the present invention is not limited to this, and for example, the blade 12 having a curved cross-sectional shape is linear. It may be the impeller 1 in which the blades of the above are alternately arranged.

Further, as another embodiment, like the blade 12A of the impeller 1A shown in FIG. 10, the cross-sectional shape bends at two inflection points and extends linearly between the back shroud 11 and the front shroud 13. You may. That is, in the cross-sectional shape, a part may be linear from the back shroud 11 of the impeller 1A toward the front shroud 13, and a part may be curved or bent.

That is, the present invention is not limited to the above embodiment, and can be variously modified at the implementation stage without departing from the gist thereof. In addition, each embodiment may be carried out in combination as appropriate, in which case the combined effect can be obtained. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by a combination selected from a plurality of disclosed constituent requirements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, if the problem can be solved and the effect is obtained, the configuration in which the constituent elements are deleted can be extracted as an invention.
The following is a description equivalent to the invention described in the claims of the original application of the present application.
[1] A back shroud that is configured in a disk shape and has a rotating shaft inserted in the center.
A plurality of blades erected on one main surface of the back shroud and having a cross-sectional shape that bends at at least one inflection point.
Impeller with.
[2] The blade projects and curves in the axial direction of the back shroud in a direction in which the back shroud side is separated from the center of the back shroud, and is curved in the axial direction of the back shroud toward the center of the back shroud on the other side. The impeller according to [1], which protrudes and curves.
[3] The impeller according to [1], wherein the center angle θ on the inlet side of the blade is 0 ° ≤ θ ≤ 70 °.
[4] The inflection point of the curved cross-sectional shape of the blade is provided in the range from the intermediate position in the height direction of the blade to the 2/3 position in the direction toward the back shroud, in [1]. The impeller described.
[5] The impeller according to any one of [2] to [4], which has a suction port in the center, covers the plurality of blades, and has a front shroud provided opposite to the back shroud.

1 ... impeller, 11 ... back shroud, 12 ... blade, 13 ... front shroud, 13a ... opening, 21 ... base, 22 ... protrusion, 101 ... impeller, 112 ... blade.

Claims (2)

A back shroud that is configured in a disk shape and a rotation axis can be inserted in the center,
A plurality of blades that are erected on one main surface of the back shroud and have a cross-sectional shape parallel to the axial direction of the back shroud that bends at one inflection point.
A front shroud provided facing the back shroud, which has a suction port in the center and covers the plurality of blades, and a front shroud.
Equipped with
The vane from the inlet side of the side edge of the blade to an intermediate portion toward the outer peripheral side of the back shroud, the back shroud side in front Symbol axial direction is curved to protrude in the direction away from the center of the back shroud, The front shroud side protrudes and curves toward the center of the front shroud in the axial direction.
Of the inlet side of the outer surface of the front Symbol vanes, the surface of the radially outer side, the radius of curvature of the back shroud side and the radius of curvature of the table shroud side are the same,
The inflection point of the curved cross-sectional shape of the blade is provided in the direction from the front shroud to the back shroud, in a range from the intermediate position of the blade to the position of 2/3 from the front shroud side of the blade. ,
An impeller having a side edge on the inlet side of the blade formed linearly in a plan view from the axial direction. The center angle θ on the inlet side of the blade is 0 ° ≦ θ ≦ 70 °.
The impeller according to claim 1, wherein the center angle θ is the angle of the side edge of the inlet portion of the blade with respect to the center line connecting the center of the impeller and the end portion of the blade in contact with the front shroud.

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