impeller

Abstract

To provide an open-type impeller capable of improving increase of pump head and efficiency when it is disposed on a centrifugal pump.SOLUTION: An impeller (10) has a circular main plate (11), and a plurality of blades (12) disposed on a surface (11a) of the main plate (11). Each of the plurality of blades (12) has a lower face (12b) fixed to the main plate (11), an upper face (12a) opposed to the lower face, a front edge (12c) at a radial inner side, and opposed two side faces (12d). At least one of the plurality of blades (12) has uneven parts (20) on the front edge (12c). The uneven parts (20) form convexoconcave when observed from one side or both sides of the side faces (12d), and form convexoconcave when observed from the front edge (12c) side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an impeller that is provided in a centrifugal pump or the like that transfers a fluid. [Background technology]

[0002] In recent years, attention has been focused on biomimetics, a technology that mimics and utilizes the diverse functions of living organisms. Nature Technology (registered trademark) is known as an example of a manufacturing company that uses biomimetic technology in electrical products and other products.

[0003] Centrifugal pumps are known as pumps for transporting fluids. They include an impeller. Impellers come in a variety of types, including a closed type in which the blades are sandwiched between a main plate and a shroud, and an open type in which the blades are exposed without a shroud.

[0004] High efficiency is desired for the impellers in such centrifugal pumps. Typically, impellers are designed based on the two-dimensional shape of the blades, but there is a limit to how much efficiency can be improved by simply changing this two-dimensional shape. Patent Document 1 discloses a configuration in which the efficiency of a closed-type impeller with a shroud is improved by providing irregularities on the leading edges of the blades. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-2689 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology disclosed in Patent Document 1 is based on a configuration having a shroud. In the case of a closed-type impeller, it is sufficient to reduce the loss in the closed flow path formed between the impeller and the shroud. However, in the case of an open-type impeller, it is also necessary to reduce the loss in the flow passing near the upper surface of the impeller.

[0007] An object of one aspect of the present invention is to provide an open-type impeller that can increase the head and improve efficiency when it is provided in a centrifugal pump. [Means for solving the problem]

[0008] In order to solve the above problems, an impeller according to one aspect of the present invention is an impeller having a circular main plate that rotates around a rotation axis, and a plurality of blades arranged on a surface of the main plate, wherein the plurality of blades have a lower surface fixed to the main plate, an upper surface opposite to the lower surface, and a radially inner The edge of the a leading edge and two opposing side surfaces, and at least one of the plurality of blades At the radially inner end, the leading edge Contains The uneven portion has a concave-convex portion, and the concave-convex portion forms an uneven portion when viewed from either one side or both sides of the side surface. Along with , and when viewed from the leading edge side too Forming unevenness a portion in which the uneven portion has a distance from a center line passing through the center of the blade in the thickness direction that decreases from the lower surface to the upper surface when viewed from the leading edge side, and the unevenness in the uneven portion as viewed from the leading edge side has a first portion in which the distance from the center line gradually decreases from the lower surface to the upper surface, and a second portion in which the distance becomes suddenly smaller than that of the first portion .

[0009] In order to solve the above problem, a pump according to one aspect of the present invention includes an impeller according to one aspect of the present invention. [Effects of the Invention]

[0010] According to one aspect of the present invention, an open-type impeller can be realized that, when provided in a centrifugal pump, can increase the head and improve efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a centrifugal pump equipped with an impeller according to an embodiment of the present invention. [Figure 2] 1 is a perspective view and an enlarged view of a main part of an impeller according to an embodiment of the present invention; [Figure 3] 3 is a diagram showing the flow of fluid relative to the blades of the impeller shown in FIG. 2. FIG. [Figure 4] FIG. 10 is a diagram illustrating the flow of fluid relative to the blades of an impeller of a comparative example. [Figure 5] 3 is a diagram illustrating the shape of the projections and recesses of the projections and recesses of the impeller shown in FIG. 2, as viewed from the side. FIG. [Figure 6] FIG. 10 is a diagram showing the flow of fluid in an impeller according to a modified example of the present embodiment. [Figure 7] 10A and 10B are diagrams showing an example of forming the unevenness as a convex or concave shape as viewed from the side; [Figure 8] FIG. 10 is an image diagram showing the flow when there are convex portions of different heights. [Figure 9] FIG. 10 is a diagram showing the relationship between the flow velocity distribution of a flow and the size of discontinuous convex portions. [Figure 10] 3A and 3B are diagrams illustrating the shape of the blades of the impeller according to the embodiment. [Figure 11] 10A and 10B are diagrams illustrating the shape of blades of an impeller according to a modified example of the present embodiment. [Figure 12] 3 is a diagram illustrating the shape of the unevenness of the impeller shown in FIG. 2, as viewed from the front edge side of the unevenness portion. FIG. [Figure 13] 10 is a diagram illustrating the shape of the irregularities of the irregularities provided on the leading edge of the blade in the impeller of the modified example, as viewed from the leading edge side. FIG. [Figure 14] 10A and 10B are diagrams illustrating the shape of the uneven portion provided on the leading edge of the blade in an impeller according to another embodiment of the present invention. [Figure 15] 10A and 10B are diagrams illustrating the shape of the uneven portion 20 provided on the leading edge of the blade in the impeller of a modified example according to the present embodiment. [Figure 16] FIG. 2 is a diagram showing the flow of fluid relative to the blades of the impeller of this embodiment, using a cross section of the blade. [Figure 17] FIG. 10 is a diagram showing the flow of fluid relative to the blades of a modified impeller, using a cross section of the blade. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Embodiment 1] Hereinafter, one embodiment of the present invention will be described in detail.

[0013] (1. Outline of centrifugal pump) FIG. 1 is a perspective view of a centrifugal pump 1 equipped with an impeller 10 according to one embodiment of the present invention. In FIG. 1, arrow Y1 indicates the flow of a fluid. As shown in FIG. 1, the centrifugal pump 1 includes a pump section 2 that delivers a fluid and a motor section 3 that drives the pump section 2. The centrifugal pump 1 draws in a fluid through an inlet opening (not shown) provided on the bottom surface of the pump section 2 and discharges the drawn-in fluid from a discharge opening 4 formed on the upper side surface of the pump section 2. The fluid may be a liquid or a gas.

[0014] The pump section 2 includes a pump case 5 having an inlet opening and a discharge opening 4 formed therein, and an impeller 10 is housed inside the pump case 5. A motor case 3a of the motor section 3 is fixed to the pump case 5.

[0015] The motor section 3 is installed on the upper surface of the pump section 2, opposite the lower surface where the inlet opening is located. The motor section 3 includes, for example, a motor case 3a and a stator (not shown) and rotor (not shown) housed inside the motor case 3a. When power is supplied to the stator, the rotor of the motor section 3 rotates, and a rotating shaft (not shown) rotates together with the rotor. The rotating shaft is provided so as to protrude toward the pump section 2, and transmits rotational force to the pump section 2 side, causing the impeller 10 to rotate.

[0016] (2. General structure of impeller) FIG. 2 is a perspective view and an enlarged view of a main portion of an impeller 10 according to one embodiment of the present invention. The impeller 10 is made of, for example, a resin material. As shown in FIG. 2, the impeller 10 has a circular main plate 11 that rotates around a rotation axis (not shown), and a plurality of (e.g., eight) blades 12 of the same shape arranged on a surface 11a, which is one surface in the thickness direction of the main plate 11. The impeller 10 is a so-called open-type impeller, in which the sides of the plurality of blades 12 opposite the main plate 11 are open.

[0017] A D-shaped connecting hole 13 into which the tip of the rotating shaft (not shown) of the motor unit 3 (see FIG. 1) is fitted is provided in the approximate center of the main plate 11. As a result, when the rotating shaft rotates due to the rotational drive of the motor unit 3, the impeller 10 rotates integrally. Note that in this embodiment, the connecting hole 13 is formed directly in the main plate 11, but, for example, a cylindrical connecting member made of a metal material or the like may be attached to the approximate center of the main plate 11 so as to be non-rotatable relative to the main plate 11.

[0018] The blades 12 are arranged side by side at equal intervals in the circumferential direction. A groove flow path 14 is formed between adjacent blades 12, allowing fluid to pass from the radially inner side to the radially outer side. The blades 12 are curved convexly in the counterclockwise direction indicated by arrow Y2. The direction indicated by arrow Y2 is the rotation direction of the impeller 10.

[0019] Each blade 12 has a lower surface 12b fixed to the main plate 11, an upper surface 12a opposite to the lower surface 12b, a radially inner leading edge 12c, and two opposing side surfaces 12d. The leading edge 12c is the radially inner edge of the blade 12. In the case of the impeller 10 shown in Fig. 2, of the two side surfaces 12d, the side surface 12d located on the front side in the rotation direction Y2 is the pressure surface side, and the side surface 12d located on the rear side in the rotation direction Y2 is the suction surface side.

[0020] The blade 12 has an uneven portion 20 on the leading edge 12c. The uneven portion 20 is uneven when viewed from the side surface 12d (either one or both of the two side surfaces 12d) and also when viewed from the leading edge 12c. The uneven portion 20 is uneven in a direction parallel to the surface 11a of the main plate 11.

[0021] In this embodiment, the uneven portion 20 is provided on the leading edge 12c of all of the plurality of blades 12. However, the uneven portion 20 may be provided on the leading edge 12c of at least one of the plurality of blades 12.

[0022] (3. Leading Edge Configuration) The shape of the leading edge 12c of the blade 12 will be described using two enlarged views of the main part shown in Figure 2. As shown in the enlarged view of reference numeral 201 in Figure 2, the uneven portion 20 forms an uneven shape when viewed from the side surface 12d. Furthermore, as shown in the enlarged view of reference numeral 202 in Figure 2, the uneven portion also forms an uneven shape when viewed from the leading edge 12c. In each of the enlarged views of reference numerals 201 and 202, the uneven portions are highlighted with thick lines.

[0023] (4. Effect of unevenness on the leading edge) The effect of the uneven portion 20 provided on the leading edge 12c will be described using Figures 3 and 4. Figure 3 is a diagram showing the flow of fluid through the blade 12 of the impeller 10 shown in Figure 1. Figure 4 is a diagram showing the flow of fluid through the blade 112 of an impeller of a comparative example. Figures 3 and 4 show a state in which the side surfaces 12d, 112d on the pressure surface side are facing upward.

[0024] 4, in the impeller blade 112 of the comparative example, which does not have the uneven portion 20 on the leading edge 112c, the flow 30 that collides with the leading edge 112c flows from the leading edge 112c to the side surface 112d while adhering to the surface of the blade 112. The flow separates from the side surface 112d midway and becomes a large vortex 33.

[0025] In contrast, as shown in Figure 3, in the blade 12 of this embodiment, the uneven portion 20 is provided on the leading edge 12c, and therefore the flow 30 that collides with the leading edge 12c is separated at the leading edge 12c by the unevenness of the uneven portion 20, and a vortex 31 is generated at the leading edge 12c. The vortex 31 is generated at the convex portion 20a of the unevenness as viewed from the side surface 12d. The generation of the vortex 31 at the leading edge 12c promotes turbulence, which encourages the flow 30 to attach to the side surface 12d. As a result, the portion where the flow 30 flows while attached to the side surface 12d (attachment portion) becomes longer than in the blade 112 of the comparative example.

[0026] Moreover, because the uneven portion 20 has an uneven appearance even when viewed from the leading edge 12c, the difference in flow of the fluid that collides with the leading edge 12c is emphasized in the height direction of the blade 12. At the leading edge 12c, the flow 30 flows along the unevenness in the thickness direction of the blade 12, sinking in the thickness direction from the convex to the concave, and flowing up in the thickness direction from the concave to the convex. The addition of this flow in the thickness direction of the blade 12 emphasizes the convex portion 20a three-dimensionally, generating a more active vortex 31 at the leading edge 12c. This promotes more turbulence than a configuration with only unevenness when viewed from the side surface 12d, and further promotes adhesion of the flow to the side surface 12d.

[0027] As a result, separation of the flow 30 from the side surface 12d of the blade 12 can be suppressed, and the fluid resistance around the blade can be reduced, which in turn can increase the head and improve the efficiency when provided in a centrifugal pump 1.

[0028] In this embodiment, the uneven portion 20 has an uneven configuration on both the pressure surface side and the suction surface side. However, separation of the flow from the side surface 12d of the blade occurs on the side surface 12d on the pressure surface side. Therefore, the uneven portion 20 may have an uneven configuration at least on the pressure surface side.

[0029] (5. Variation of unevenness as seen from the side of the uneven part) Figure 5 is a diagram illustrating the shape of the concave-convex portion 20 of the impeller 10 shown in Figure 2, as viewed from the side surface 12d. The view indicated by reference numeral 501 in Figure 5 is a view from the side surface 112d of a blade 112 having a conventional configuration, and the view indicated by reference numeral 502 is a view from the top surface 112a of the blade 112. When viewed from the side surface 112d, the leading edge 112c of the blade 112 is linearly inclined from the top surface 112a to the bottom surface 112b.

[0030] The diagram indicated by reference numeral 503 is a view of the blade 12 of this embodiment as viewed from the side surface 12d. As shown in the diagram indicated by reference numeral 503, the unevenness as viewed from the side surface 12d can be formed by providing a convex shape that is convex toward the upstream of the flow direction indicated by Y3 on the linear leading edge 112c of the blade 112 of a conventional configuration. In the diagram indicated by reference numeral 503, two convex shapes form two convex portions 20a along the height direction of the blade 12. A concave portion 20b is formed between the two convex shapes. The impeller 10 shown in FIG. 2 has such convex shapes formed as unevenness as viewed from the side surface 12d.

[0031] The diagram indicated by reference numeral 504 is a view from the side surface 12d of the blade 12A included in the impeller of a modified example of this embodiment. As shown in the diagram indicated by reference numeral 504, the unevenness seen from the side surface 12d can also be formed as a concave shape that is concave toward the downstream of the flow direction indicated by Y3 on the linear leading edge 112c of the blade 112 of a conventional configuration. In the diagram indicated by reference numeral 504, concave shapes are formed in two locations along the height direction of the blade 12A, thereby forming three convex portions 20a. Note that when forming concave shapes, two convex portions 20a are formed so that one concave shape is sandwiched between them.

[0032] Figure 6 is a diagram showing the fluid flow in an impeller according to a modified example of this embodiment. As shown in Figure 6, in this case as well, as in Figure 3, vortices 31 are generated at leading edge 12c, promoting turbulence and encouraging flow 30 to adhere to side surface 12d, thereby lengthening the portion of flow 30 that adheres to side surface 12d and flows. Furthermore, because the surface is uneven when viewed from the leading edge 12c side, convex portion 20a is emphasized three-dimensionally, allowing for the generation of more active vortices 31 at leading edge 12c.

[0033] At least one convex portion 20a in the unevenness as viewed from the side surface 12d may be provided, but multiple convex portions 20a may also be provided along the direction in which the leading edge 12c extends (the height direction of the blade 12), as shown in the figures indicated by the reference numerals 503 and 504.

[0034] With this configuration, vortices 31 can be generated at multiple locations in the direction in which leading edge 12c extends. Therefore, the portion in which flow 30 flows along side surface 12d of the blade becomes longer over a wide area in the height direction of blade 12, and fluid resistance around the blade can be reduced more effectively.

[0035] When multiple convex portions 20a are provided, the multiple convex portions 20a may be provided continuously or discontinuously with a gap between each convex portion 20a. Furthermore, when there are multiple convex portions 20a, they may be connected by a curve in the height direction of the blade 12. This configuration can promote vortex generation at the convex portions 20a while smoothing the flow of fluid on the surfaces of the convex portions 20a. Therefore, unnecessary fluid resistance can be suppressed.

[0036] Furthermore, when there are multiple convex portions 20a, the heights of the multiple convex portions 20a may be uniform. In other words, when the unevenness seen from the side surface 12d is formed in a convex shape, the convex amount of the convex shape is uniform, and when the unevenness seen from the side surface 12d is formed in a concave shape, the concave amount of the concave shape is uniform.

[0037] Fig. 7 is a diagram showing an example of forming the unevenness as viewed from the side surface 12d side in a convex or concave shape. The diagram indicated by reference numeral 701 in Fig. 7 is an example of forming the unevenness as viewed from the side surface 12d side in a convex shape. The diagram indicated by reference numeral 702 is an example of forming the unevenness as viewed from the side surface 12d side in a concave shape.

[0038] When forming a convex shape, as shown in the diagram indicated by the reference numeral 701, a line L1 parallel to the baseline L connecting the upper surface 12a and the lower surface 12b at the leading edge 12c is drawn upstream in the flow direction indicated by Y3, and the apex of the convex shape is aligned with the position of the line L1.

[0039] When forming a concave shape, as shown in the diagram indicated by the reference numeral 702, a line L2 parallel to the baseline L is drawn downstream in the flow direction indicated by Y3, and the bottom of the concave shape is aligned with the position of the line L2.

[0040] By aligning the heights of the multiple convex portions 20a, it is possible to generate vortices 31 that are less likely to interfere with each other. If the heights of the convex portions 20a are not uniform, as shown in FIG. 8, vortices 31A generated at relatively tall convex portions 20a among the multiple convex portions 20a will obstruct the flow flowing into adjacent convex portions 20a. This makes it easier for the vortices 31 to interfere with each other, resulting in mutual loss. This does not promote turbulence, weakening the effect of promoting flow adhesion to the side surface 12d. FIG. 8 is an image diagram showing the flow when convex portions 20a of different heights are present.

[0041] Furthermore, convex portion 20a may be provided at a position closer to upper surface 12a than the midpoint between upper surface 12a and lower surface 12b. With this configuration, vortices 31 are generated near upper surface 12a, promoting turbulence, thereby encouraging the flow to adhere not only to the side surface of blade 12 but also to upper surface 12a of the blade.

[0042] In this case, the convex portion 20a may be provided within 30% of the top surface. With this configuration, vortices 31 are generated within 30% of the top surface, promoting turbulence, which effectively encourages the flow to adhere to the top surface 12a of the blade.

[0043] Furthermore, when multiple convex portions 20a are provided, as shown in Figure 9, the convex portions 20a located closer to the lower surface 12b may be configured to be larger in size as viewed from the side surface 12d than the convex portions 20a located closer to the upper surface 12a.

[0044] 9 is a diagram showing the relationship between the flow velocity distribution of the flow and the size of the discontinuous convex portions 20a. As shown in Fig. 9, the velocity of the flow 30 increases as it approaches the upper surface 12a from the lower surface 12b. Vortices 31 are easily generated on the upper surface 12a side where the velocity of the flow 30 is high, but vortices 31 are difficult to generate on the lower surface 12b where the velocity of the flow 30 is low.

[0045] Therefore, by making the convex portion 20a larger on the lower surface 12b side where the flow is slower and making the convex portion 20a smaller on the upper surface 12a side where the flow is faster, it is possible to generate vortices 31 evenly in the height direction of the blade 12 (12A). As a result, the distance of the part where the fluid adheres to the side surface 12d of the blade and flows can be made uniform in the height direction of the blade 12 (12A).

[0046] Here, the size of the convex portion 20a refers to the size in the height direction of the blade 12 (12A), and may include the height (protrusion amount) of the convex portion 20a itself. Furthermore, when the size of the convex portion 20a is changed, the shape of the convex portion 20a may be made similar when viewed from the side surface 12d. By making the shape of the convex portion 20a uniform, the state of the generated vortex 31 can be made uniform.

[0047] (6. Manufacturing Constraints) As described above, the impeller 10 in this embodiment is made of, for example, a resin material. In this case, the shape of the upper surface 12a when viewed in a plan view from the normal direction of the surface 11a of the main plate 11 needs to be smaller than the shape of the lower surface 12b when viewed in a plan view from the normal direction (constraint) so that the impeller can be removed from a mold.

[0048] Figure 10 is a diagram illustrating the shape of the blade 12 of the impeller 10 according to this embodiment. The diagram 1001 in Figure 10 is a top view of the blade 12, and the diagram 1002 is a cross-sectional view of the diagram 1001 taken along line AA. The diagram 1003 is a front view of the pressure surface side of the blade 12 as seen from the leading edge 12c side.

[0049] Due to the above constraints, as shown in the diagram indicated by the reference numeral 1002, the length of the leading edge 12c in the direction in which the blade 12 extends becomes shorter from the lower surface 12b toward the upper surface 12a when viewed from the side surface 12d, and under this condition, the leading edge 12c forms an uneven shape. In other words, the length of the leading edge 12c in the direction in which the blade 12 extends is gradually shortened from the lower surface 12b toward the upper surface 12a, and the length of the leading edge 12c is divided into a first region M1 where the length gradually shortens from the lower surface 12b toward the upper surface 12a, and a second region M2 where the length becomes shorter than the first region M1 more rapidly. There is an inflection point between the first region M1 and the second region M2.

[0050] Similarly, due to the above constraints, as shown in the drawing of reference numeral 1003, when viewed from the leading edge 12c side, the distance from the center line L4 passing through the center of the thickness direction of the blade 12 becomes smaller as one moves from the lower surface 12b to the upper surface 12a, and under this condition, the leading edge 12c forms an uneven shape. In other words, as one moves from the lower surface 12b to the upper surface 12a, the distance from the center line L4 becomes Sudden The third part (the 2 Part) M3 and the third part M3 slow The fourth part (the 1 The third portion M3 and the fourth portion M4 are inflection points. The third portion M3 and the fourth portion M4 are shown in the drawing 1003 in an emphasized manner.

[0051] Figure 11 is a diagram illustrating the shape of a blade 12A of an impeller according to a modified example of this embodiment. In Figure 11, reference numeral 1101 is a top view of the blade 12A, and reference numeral 1102 is a cross-sectional view taken along line AA of reference numeral 1101. Reference numeral 1103 is a front view of the pressure surface side of the blade 12A as viewed from the leading edge 12c side.

[0052] Due to the above constraints, the leading edge 12c of the modified blade 12A also has an uneven shape under the condition that the length of the blade 12 in the direction of extension becomes shorter from the lower surface 12b toward the upper surface 12a as shown in the diagram indicated by the reference numeral 1102 when viewed from the side surface 12d. That is, the blade 12 has a first region M1 where the length of the blade 12 in the direction of extension gradually becomes shorter from the lower surface 12b toward the upper surface 12a, and a second region M2 where the length becomes shorter than the first region M1 more abruptly. There is an inflection point between the first region M1 and the second region M2.

[0053] Similarly, due to the above constraints, as shown in the diagram indicated by reference numeral 1103, when viewed from the leading edge 12c side, the distance from the center line L4 passing through the center of the blade 12 in the thickness direction decreases from the lower surface 12b to the upper surface 12a, forming an uneven shape under this condition. In other words, the blade 12 has a third region (first portion) M3 where the distance from the center line L4 gradually decreases from the lower surface 12b to the upper surface 12a, and a fourth region (second portion) M4 where the distance becomes more abruptly smaller than the third region M3. An inflection point exists between the third region M3 and the fourth region M4. Note that the third region M3 and the fourth region M4 are emphasized in the diagram indicated by reference numeral 1003.

[0054] (7. Variation of unevenness as seen from the leading edge of the uneven part) Fig. 12 is a diagram illustrating the shape of the concaves and convexes of the concave-convex portion 20 in the impeller shown in Fig. 2, as viewed from the leading edge 12c side. The diagram 1201 in Fig. 12 is a diagram viewed from the side surface 12d side of the blade 12. The diagrams 1202 to 1205 are cross-sectional views taken along lines AA to DD in the diagram 1201. The cross-sections along lines AA to DD are cross-sections of the blade 12 parallel to the surface 11a of the main plate 11. Hereinafter, the cross-section parallel to the surface 11a of the main plate 11 will be referred to as the cross-section of the blade.

[0055] In the blade 112 of the conventional configuration, the leading edge 112c has a convex curved shape in cross section, and the curvature is uniform in the height direction of the blade 112 (see the drawing of reference numeral 502 in FIG. 5).

[0056] In contrast, as shown in Fig. 12, the curvature of the convex curved shape of the leading edge 12c in the cross section of the blade 12 varies in the height direction of the blade 12. By varying the curvature of the convex curved shape in the height direction of the blade 12, concaves and convexes are formed as viewed from the leading edge 12c side. In the example of Fig. 12, the curvature varies from large to small from the upper surface 12a to the lower surface 12b.

[0057] That is, in the cross section, the leading edge 12c has a convex curved shape, and the curvature of this convex curved shape changes in the height direction of the blade 12. In other words, by changing the curvature of the convex curved shape of the leading edge 12c in the cross section of the blade 12 in the height direction of the blade 12, unevenness as seen from the leading edge 12c side is formed. With this configuration, unevenness as seen from the leading edge 12c side can be easily created despite the manufacturing constraints described above.

[0058] Fig. 13 is a diagram illustrating the shape of the unevenness of uneven portion 20 provided on leading edge 12c of blade 12A in an impeller of a modified example, as viewed from leading edge 12c. Diagram 1301 in Fig. 13 is a diagram viewed from side surface 12d of blade 12A. Diagrams 1302 to 1307 are cross-sectional views taken along lines AA to FF in diagram 1301. The cross sections taken along lines AA to FF are transverse cross-sections of blade 12A.

[0059] As shown in Fig. 13, in blade 12A as well, the curvature of the convex curved shape of leading edge 12c in the cross section of blade 12 changes in the height direction of blade 12, thereby forming concaves and convexes as viewed from leading edge 12c. In the example of Fig. 13, the curvature changes from small to large and then from large to small from upper surface 12a to lower surface 12b.

[0060] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0061] In the impeller according to this embodiment, the relationship between the concave and convex portions 20 provided on the leading edge 12c of the blade 12B when viewed from the side surface 12d matches the relationship between the concave and convex portions or the convex and convex portions when viewed from the leading edge 12c. This is the difference from the impeller 10 according to the above-described embodiment.

[0062] Specifically, the convex or concave portions of the unevenness as viewed from the leading edge 12c correspond to the convex portions 20a of the unevenness as viewed from the side surface 12d, and the concave portions 20b of the unevenness as viewed from the side surface 12d correspond to the convex or concave portions of the unevenness as viewed from the leading edge 12c. With this configuration, the convex portions 20a that generate the vortex 31 can be made to stand out even more three-dimensionally, promoting the generation of the vortex.

[0063] Fig. 14 is a diagram illustrating the shape of the uneven portion 20 provided on the leading edge 12c of the blade 12B in the impeller according to this embodiment. In Fig. 14, the diagram designated by reference numeral 1401 is a top view of the blade 12B, and the diagram designated by reference numeral 1402 is a cross-sectional view taken along line AA of the diagram designated by reference numeral 1401. The diagram designated by reference numeral 1403 is a front view of the pressure surface side of the blade 12B as viewed from the leading edge 12c side. Furthermore, the diagrams designated by reference numerals 1404 to 1406 are cross-sectional views taken along lines BB to DD of the diagram designated by reference numeral 1403. The cross-sections taken along lines BB to DD are transverse cross-sections of the blade 12B.

[0064] As shown in Fig. 14, in blade 12B, the curvature of the convex curved shape of leading edge 12c in the cross section of blade 12B changes in the height direction of blade 12B in accordance with the unevenness as seen from side surface 12d. In the example of Fig. 14, the curvature gradually changes from being larger at concave portion 20b (see drawings indicated by reference numerals 1404 and 1406) to being smaller at convex portion 20a (see drawing indicated by reference numeral 1405). Note that line L5 in drawing indicated by reference numeral 1403 is a line connecting points that emphasize the unevenness as seen from the leading edge 12c, and drawing indicated by reference numeral 1403 illustrates the unevenness in an emphasized manner.

[0065] Fig. 15 is a diagram illustrating the shape of the uneven portion 20 provided on the leading edge 12c of the blade 12C in an impeller according to a modified example of this embodiment. In Fig. 15, the diagram designated by reference numeral 1501 is a top view of the blade 12C, and the diagram designated by reference numeral 1502 is a cross-sectional view taken along line AA of the diagram designated by reference numeral 1501. The diagram designated by reference numeral 1503 is a front view of the pressure surface side of the blade 12C as viewed from the leading edge 12c side. Furthermore, the diagrams designated by reference numerals 1504 to 1506 are cross-sectional views taken along lines BB to DD of the diagram designated by reference numeral 1503. The cross-sections taken along lines BB to DD are transverse cross-sections of the blade 12C.

[0066] 15, in the blade 12C, the curvature of the convex curved shape of the leading edge 12c in the cross section gradually changes from being smaller at the concave portion 20b (see the diagrams denoted by reference numerals 1504 and 1506) to being larger at the convex portion 20a (see the diagram denoted by reference numeral 1505). Note that the line L5 in the diagram denoted by reference numeral 1503 is a line connecting points that emphasize the concaves and convexes as viewed from the leading edge 12c side, and the diagram denoted by reference numeral 1503 is illustrated so that the concaves and convexes are emphasized.

[0067] The effects of the configurations shown in Figures 14 and 15 will be described using Figures 16 and 17. Figure 16 is a diagram showing the flow of fluid through impeller blade 12B of this embodiment, using a cross section of blade 12B. Figure 17 is a diagram showing the flow of fluid through impeller blade 12C of a modified example, using a cross section of blade 12C. Figures 16 and 17 show the state in which side surface 12d on the pressure surface side faces upward. In Figures 16 and 17, the magnitudes shown in parentheses indicate the magnitudes of the curvatures of the corresponding parts.

[0068] As shown by arrow Y5 in Figures 16 and 17, the fluid flows downward in the thickness direction of blade 12B or 12C in the area where the curvature changes from small to large. Conversely, the fluid flows upward in the thickness direction of blade 12B or 12C in the area where the curvature changes from large to small. This difference in the flow in the thickness direction (arrow Y5) combined with the irregularities seen from side surface 12d that generate convex portion 20a that generates vortex 31 further emphasizes convex portion 20a in a three-dimensional manner. As a result, more active vortices 31 are generated at leading edge 12c, further promoting the flow's adhesion to side surface 12d.

[0069] 〔summary〕 An impeller according to a first aspect of the present invention is an impeller having a circular main plate that rotates around a rotation axis, and a plurality of blades arranged on the surface of the main plate, wherein the plurality of blades have a lower surface fixed to the main plate, an upper surface opposite the lower surface, a radially inner leading edge, and two opposing side surfaces, and at least one of the plurality of blades has an uneven portion on the leading edge, and the uneven portion forms an uneven portion when viewed from either one or both of the side surfaces, and also forms an uneven portion when viewed from the leading edge side.

[0070] A second aspect of the present invention is directed to the impeller of the first aspect, wherein the uneven portion forms unevenness on the pressure surface side.

[0071] An impeller according to a third aspect of the present invention is the impeller of the first or second aspect, wherein the relationship of the concave-convex portions when viewed from the side surface matches the relationship of the concave-convex or convex-concave portions when viewed from the leading edge side.

[0072] The impeller according to aspect 4 of the present invention is any one of aspects 1 to 3 above, in which the convex portion of the unevenness as viewed from the side is located closer to the upper surface than the midpoint between the upper surface and the lower surface.

[0073] An impeller according to a fifth aspect of the present invention is any one of the first to fourth aspects, wherein a plurality of convex portions in the concave-convex portions as viewed from the side surface are provided along the direction in which the leading edge extends.

[0074] In a sixth aspect of the present invention, the impeller of the fifth aspect is such that the heights of the plurality of convex portions are uniform.

[0075] An impeller according to a seventh aspect of the present invention is the impeller of the fifth or sixth aspect, wherein the plurality of protruding portions are connected by a curve in the direction in which the leading edge extends.

[0076] An impeller according to aspect 8 of the present invention is any one of aspects 5 to 7 above, wherein the multiple convex portions closer to the lower surface are larger in size as viewed from the side than the convex portions closer to the upper surface.

[0077] The impeller according to aspect 9 of the present invention is any one of aspects 1 to 8 above, wherein in a cross section parallel to the surface, the leading edge has a convex curved shape, and the curvature of the convex curved shape varies in the height direction of the blade.

[0078] The impeller according to aspect 10 of the present invention is any one of aspects 1 to 9 above, wherein the unevenness as viewed from the leading edge side has a first portion in which the distance from a center line passing through the center of the thickness direction of the blade gradually decreases from the lower surface to the upper surface, and a second portion in which the distance becomes suddenly smaller than the first portion.

[0079] A pump according to an eleventh aspect of the present invention includes the impeller according to any one of the first to tenth aspects.

[0080] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0081] The present disclosure includes a technical idea focusing on the fins of humpback whales, that is, the present invention relates to biomimetics. [Explanation of symbols]

[0082] 1. Centrifugal pump (pump) 10 impeller 12, 12A, 12B, 12C, 12C blade 11 Main plate 11a surface 12a top surface 12b Bottom side 12c leading edge 12d side 14 Groove channel 20 Uneven part 20a Convex part 20b concave part 30 Flow 31 Vortex L4 Chuo Line Y2 rotation direction

Claims

1. An impeller having a circular main plate that rotates around a rotation axis and a plurality of blades arranged on a surface of the main plate, each of the plurality of blades has a lower surface fixed to the main plate, an upper surface opposite to the lower surface, a leading edge that is a ridge line of an end portion on an inner side in the radial direction, and two opposing side surfaces; At least one of the plurality of blades has an uneven portion including the leading edge at an end portion on the inner side in the radial direction, The uneven portion is a portion that forms an uneven shape when viewed from either one side or both sides of the side surface and also forms an uneven shape when viewed from the leading edge side, When viewed from the leading edge side, the uneven portion has a distance from a center line passing through a center in a thickness direction of the blade that decreases from the lower surface to the upper surface, The unevenness of the uneven portion, as viewed from the leading edge side, has a first portion in which the distance from the center line gradually decreases from the lower surface to the upper surface, and a second portion in which the distance from the center line suddenly becomes smaller than the first portion.

2. The impeller according to claim 1 , wherein the uneven portion forms unevenness on the pressure surface side.

3. The impeller according to claim 1 or 2, wherein the relationship of the concave and convex portions when viewed from the side surface matches the relationship of the concave and convex portions or the relationship of the convex and convex portions when viewed from the leading edge.

4. The impeller according to claim 1 , wherein the convex portions of the irregularities as viewed from the side are located closer to the upper surface than to a midpoint between the upper surface and the lower surface.

5. The impeller according to claim 1 , wherein a plurality of convex portions in the concave-convex portions as viewed from the side are provided along the direction in which the leading edge extends.

6. If the distance between a straight line connecting the bottoms of the plurality of recessed portions in the unevenness seen from the side and the radially inner end of the convex portion is defined as the height of the convex portion, The impeller according to claim 5 , wherein the plurality of protruding portions have the same height.

7. The impeller according to claim 5 or 6, wherein the plurality of protruding portions are connected by a curve in the direction in which the leading edge extends.

8. Among the plurality of convex portions, when viewed from the side surface, a convex portion having concave portions on both sides thereof along the extending direction is defined as a first convex portion, 8. The impeller according to claim 5, wherein the first convex portions located closer to the lower surface have a larger dimension in the height direction of the blades than the first convex portions located closer to the upper surface.

9. In a cross section parallel to the surface, the leading edge has a convex curved shape; The impeller according to any one of claims 1 to 8, wherein the curvature of the convex curved shape varies in the height direction of the blade.

10. A pump comprising an impeller according to any one of claims 1 to 9.

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