Impeller fixed to rotating shaft of turbo pump and method for manufacturing the same

Abstract

To provide an impeller that provides the same function as a skewed impeller and is easy to manufacture.SOLUTION: There is proposed an impeller that is fixed to the rotating shaft of a turbo pump, and that comprises a main plate and a side plate fixed to the rotating shaft, and a blade part that is disposed between the main plate and the side plate and has a plurality of spiral blades. At the outer peripheral side ends of the plurality of blades, the blade surface facing a rotation direction has a first straight line portion that is connected to the main plate and extends parallel to the rotation axis, and a first curved line portion that is connected to the side plate, continues to the first straight line portion and is smoothly inclined. The blade surface facing away from the rotation direction has a second straight line portion that is connected to the side plate and extends parallel to the rotation axis, and a second curved line portion that is connected to the main plate, continues to the second straight line portion and is smoothly inclined in the same direction as the first curved line portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an impeller fixed to a rotating shaft of a turbo pump, and a method for manufacturing the same. [Background technology]

[0002] Centrifugal pumps such as volute pumps are known as turbo pumps that transfer liquid (e.g., water) by imparting energy to the liquid by rotating an impeller within a casing (see Patent Document 1). The volute pump includes a rotating shaft to which the impeller is fixed, and a casing that houses the impeller and forms a flow path for the liquid. The volute pump pressurizes the liquid within the casing by rotating the impeller within the casing, and discharges the pressurized liquid from a discharge port to the outside. The impellers used in such turbo pumps are manufactured by, for example, casting (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-312187 [Patent Document 2] Japanese Utility Model Application Publication No. 7-26044 Summary of the Invention [Problem to be solved by the invention]

[0004] In an impeller used in a turbo pump, a skew (blade inclination) may be provided so that the blade surfaces of the blades are inclined in the circumferential direction at the outlet side. By providing a skew, for example, it is possible to improve the stability when transferring a flow rate less than the design point, thereby improving the function of the turbo pump. However, providing a skew to an impeller may cause a manufacturing problem due to the complexity of the impeller shape. For example, when an impeller without a skew is manufactured by casting, a wooden mold imitating the blades can be removed by vertically removing it from a sand mold, but when an impeller with a skew is manufactured by casting, it is not possible to vertically remove the wooden mold from the mold, which may make it difficult to manufacture the sand mold.

[0005] The present invention has been made to solve at least one of the above problems, and one of its objects is to provide an impeller that provides the same function as a skewed impeller and is easy to manufacture. [Means for solving the problem]

[0006] According to one embodiment of the present invention, there is proposed an impeller fixed to a rotating shaft of a turbo pump, the impeller comprising a main plate and a side plate fixed to the rotating shaft, and a plurality of blades arranged between the main plate and the side plate, wherein the blade surfaces facing the direction of rotation at the outer peripheral ends of the plurality of blades have a first straight portion connected to the main plate and extending parallel to the rotation axis, and a first curved portion connected to the side plate and continuing to the first straight portion and smoothly inclined, and the blade surfaces facing away from the direction of rotation have a second straight portion connected to the side plate and extending parallel to the rotation axis, and a second curved portion connected to the main plate and continuing to the second straight portion and smoothly inclined in the same direction as the first curved portion. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a side view showing a schematic diagram of an impeller according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a flow path of the impeller shown in FIG. [Diagram 3] FIG. 2 is a side view showing a flow path of the impeller shown in FIG. [Figure 4] FIG. 2 is a perspective view showing a schematic example of a flow path of an impeller without skew. [Diagram 5] FIG. 2 is a side view showing a schematic example of a flow path of an impeller without skew. [Figure 6] FIG. 2 is a perspective view showing a schematic example of a flow path of a skewed impeller. [Figure 7] FIG. 2 is a side view showing a schematic diagram of an example of a flow path of a skewed impeller. [Figure 8] FIG. 2 is a diagram showing a vane mold and a base mold according to one embodiment. [Figure 9] FIG. 2 is a schematic diagram of a base mold in one embodiment. [Figure 10] FIG. 2 is a schematic diagram of a mold according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals and redundant description will be omitted.

[0009] FIG. 1 is a side view showing a schematic diagram of an impeller according to an embodiment of the present invention. The impeller 10 shown in FIG. 1 is fixed to a rotating shaft (not shown) of a turbo pump such as a centrifugal pump, and is configured to pump liquid with the rotation of the rotating shaft. The impeller 10 includes a main plate 12, a side plate 14, and a blade portion 20. The main plate 12 and the side plate 14 are fixed to a rotating shaft (not shown) of the turbo pump. The blade portion 20 is disposed between the main plate 12 and the side plate 14, and is sandwiched between the main plate 12 and the side plate 14. The blade portion 20 may be fixed to the rotating shaft via the main plate 12 and the side plate 14, or may be fixed directly to the rotating shaft. In FIG. 1, the outer peripheral end surface of one blade 22 in the blade portion 20 is hatched.

[0010] 2 and 3 are a perspective view and a side view showing the flow path of the impeller 10 shown in FIG. 1. That is, in FIG. 2 and FIG. 3, the flow path through which the liquid passes is defined by the main plate 12, the side plate 14, and the blade portion 20 in the impeller 10. The blade portion 20 has a plurality of blades 22 (five in the example shown in FIG. 2 and FIG. 3) that are arranged at equal intervals in the circumferential direction and extend in a spiral shape. In FIG. 2 and FIG. 3, the gaps in the spiral flow path correspond to the blades 22, and the blade portion 20 and the blades 22 are indirectly shown. The plurality of blades 22 each have the same shape. The plurality of blades 22 have a blade surface 24 that faces the rotation direction and serves as a pressure surface, and a blade surface 26 that faces away from the rotation direction and serves as a negative pressure surface. The gaps between the plurality of blades 22 become the flow path of the liquid to be pumped by the turbo pump. 2 and 3, the blade surface 24 and the blade surface 26 of one blade 22 are shown hatched. As the impeller 10 rotates, liquid is transferred from the flow path inlet 16 on the inner circumference side to the flow path outlet 18 on the outer circumference side.

[0011] The shape of the outer peripheral end (outlet end) of the blades 22 will be described. At the outer peripheral end of the blades 22, the blade surface 24 facing the rotation direction has a first straight portion 241 connected to the main plate 12 and extending parallel to the rotation axis Xc (see FIG. 3), and a smoothly inclined first curved portion 242 connected to the side plate 14 and continuing to the first straight portion 241. In other words, the first straight portion 241 has one end connected to the main plate 12 and extends in the blade height direction of the blades 22 (up and down direction in FIG. 1 and FIG. 3). As an example, the first straight portion 241 occupies an area of ​​40%, 50%, or 60% of the blade height Hw at the outer peripheral end from the main plate 12. The first curved portion 242 extends continuously from the other end of the first straight portion 241 to the side plate 14. The first curved portion 242 is smoothly inclined from the first straight portion 241 in the direction in which the liquid flow path widens. Here, "smoothly inclined" can be said to mean that the curved portion is substantially tangent continuous, and preferably curvature continuous. It is particularly preferable that the first curved portion 242 is formed with a constant curvature Ra from the first straight portion 241 to the side plate 14. As an example, the curvature Ra is approximately half the blade height Hw at the outer circumferential end.

[0012] At the outer peripheral end of each of the blades 22, the blade surface 26 facing away from the rotation direction has a second straight portion 261 connected to the side plate 14 and extending parallel to the rotation axis Xc, and a second curved portion 262 connected to the main plate 12 and continuing to the second straight portion 261 with a smooth inclination. The straight portion 261 is diagonally positioned with respect to the first straight portion 241, and the second curved portion 262 is diagonally positioned with respect to the first curved portion 242. For example, the second straight portion 261 occupies 40%, 50%, or 60% of the blade height Hw at the outer circumferential end from the side plate 14. The second straight portion 261 may have the same length as the first straight portion 241. The second curved portion 262 extends continuously from the other end of the second straight portion 261 to the main plate 12. The second curved portion 262 is smoothly inclined from the second straight portion 261 in the direction in which the liquid flow path widens. For example, in the circumferential direction, the length L1 of the first curved portion 242 and the length L2 of the second curved portion 262 are the same. It is particularly preferable that the second curved portion 262 is formed with a constant curvature Rb from the second straight portion 261 to the main plate 12. The curvature Rb is, for example, approximately half the blade height Hw of the outer circumferential end portion. The curvature Rb may be the same as the curvature Ra of the first curved portion 242, and the first curved portion 242 and the second curved portion 262 may have the same shape.

[0013] Here, an impeller of a comparative example will be described. Fig. 4 and Fig. 5 are a perspective view and a side view showing an example of a flow path of an impeller without a skew, and Fig. 6 and Fig. 7 are a perspective view and a side view showing an example of a flow path of an impeller with a skew. In Fig. 4 to Fig. 7, the blade portion and the blade are indirectly shown, as in Fig. 2 and Fig. 3. The impeller of the comparative example shown in Fig. 4 to Fig. 7 is different from the impeller 10 of the present embodiment in the shape of the outer peripheral end of the multiple blades 22, and is otherwise generally the same. At the outer peripheral end of the multiple blades 122 (blade portion 120) in the impeller 110 shown in Fig. 4 and Fig. 5, both the blade surface 124 facing the rotation direction and the blade surface 126 facing away from the rotation direction extend along the rotation axis Xc from the main plate to the side plate. In addition, at the outer peripheral end of the multiple blades 222 (blade portion 220) in the impeller 210 shown in Figures 6 and 7, both the blade surface 224 facing the rotation direction and the blade surface 226 facing away from the rotation direction are linearly inclined with respect to the rotation axis Xc from the main plate to the side plate. Such a blade inclination is also called skew. In the impeller 210 with skew shown in Figures 6 and 7, the pressure field in the blade flow path can be optimized compared to the impeller 110 without skew shown in Figures 4 and 5, and for example, stability can be improved when transporting a low flow rate. On the other hand, if the outer peripheral end of the multiple blades is skewed, the shape of the impeller becomes complicated, and it may be difficult to form the vicinity of the skew in particular.

[0014] In contrast, in the impeller 10 of this embodiment, the blade surface 24 facing the rotation direction and the blade surface 26 facing away from the rotation direction are formed at the outer circumferential end of the multiple blades 22 so as to have straight portions (first straight portion 241, second straight portion 261) and curved portions (first curved portion 242, second curved portion 262) at diagonal positions. The impeller 10 of this embodiment can optimize the pressure field in the blade flow path similar to the skewed impeller 210. Furthermore, the impeller 10 of this embodiment can be manufactured more easily than the skewed impeller 210.

[0015] Next, a manufacturing method of the impeller 10 of this embodiment will be described. The impeller 10 of this embodiment can be manufactured by casting, for example. However, the impeller 10 is not limited to being manufactured by casting, and may be manufactured by bending, cutting, or additive manufacturing using an AM device. The impeller 10 may also be manufactured by connecting a plurality of members by welding or bonding, for example, by forming the main plate 12, the side plate 14, and the blade portion 20 separately. A method of manufacturing the impeller 10 by casting will be further described below as an example.

[0016] In a method for manufacturing the impeller 10 according to one embodiment by casting, first, a blade mold is prepared that imitates the plurality of blades 22A whose outer circumferential ends are formed to extend parallel to the rotation axis from the main plate side to the side plate side. As an example, the blade mold can be a mold having the same shape as the blade portion 120 of the non-skewed impeller 110 shown in Figs. 4 and 5. The blade mold can be used by any method. The blade mold can be made by cutting wood or resin, or by additive manufacturing using an AM device. Next, a base mold (base core) is formed using the blade mold. The base mold can be formed, for example, by filling molding sand around the blade mold and solidifying it. FIG. 8 is a diagram showing a blade mold and a base mold in one embodiment. FIG. 8 shows an outer peripheral end of one blade 22A of the blade mold and a base mold 310. When the base mold 310 is formed, the blade mold is removed from the base mold 310. FIG. 9 is a diagram showing a base mold in one embodiment. In this embodiment, the blade mold can be removed by pulling it out vertically from the base mold 310 because the outer peripheral end of the multiple blades 22A is formed without skew. This makes it easier to form the base mold 310 than when the impeller 210 with skew shown in FIG. 6 and FIG. 7 is used as the blade mold.

[0017] Next, a mold (core) is formed by cutting the portions of the base mold corresponding to the first curved portion 242 and the second curved portion 262. FIG. 10 is a diagram showing a mold in one embodiment. As shown in FIG. 10, a part of the base mold 310 formed with a vane mold without a skew is cut, so that the mold 320 has a portion 322 corresponding to the first curved portion 242 and a portion 324 corresponding to the second curved portion 262. The uncut portion of the base mold 310 formed with a vane mold without a skew constitutes the portions corresponding to the first straight portion 241 and the second straight portion 261. In this way, by forming and cutting the base mold 310 using a vane mold without a skew, the mold 320 of the impeller 10 can be easily formed. Then, the impeller 10 can be cast using the mold 320 thus formed, so that the above-mentioned impeller 10 can be easily manufactured.

[0018] The present embodiment described above can also be described as the following embodiment. [Mode 1] According to mode 1, an impeller fixed to a rotating shaft of a turbo pump is proposed, comprising a main plate and a side plate fixed to the rotating shaft, and a blade section having a plurality of spiral blades arranged between the main plate and the side plate, and at the outer circumferential end of the plurality of blades, a blade surface facing the direction of rotation has a first straight portion connected to the main plate and extending parallel to the rotation axis, and a first curved portion connected to the side plate and continuing to the first straight portion, and a blade surface facing away from the direction of rotation has a second straight portion connected to the side plate and extending parallel to the rotation axis, and a second curved portion connected to the main plate and continuing to the second straight portion, and smoothly inclined in the same direction as the first curved portion. According to mode 1, it is possible to provide an impeller that produces the same function as a skewed impeller and is easy to manufacture.

[0019] [Mode 2] According to Mode 2 in the configuration of Mode 1, the first curved portion and the second curved portion have the same length in the circumferential direction.

[0020] [Feature 3] According to feature 3, in feature 1 or 2, the first curved portion and the second curved portion have the same shape.

[0021] [Mode 4] According to Mode 4, in Modes 1 to 3, each of the first curved portion and the second curved portion is configured to have a curved shape with a constant curvature.

[0022] [Mode 5] According to Mode 5, a manufacturing method for manufacturing the impellers of Modes 1 to 4 is proposed, and the manufacturing method includes the steps of preparing an impeller mold imitating a plurality of impellers whose outer circumferential ends extend parallel to the rotation axis from the main plate side to the side plate side, forming a base mold using the impeller mold, cutting portions of the base mold corresponding to the first curved portion and the second curved portion to form a mold, and casting the impeller using the mold. According to Mode 5, the impellers of Modes 1 to 4 can be easily manufactured by casting.

[0023] Although the embodiment of the present invention has been described above, the above-mentioned embodiment of the invention is intended to facilitate understanding of the present invention and does not limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention naturally includes equivalents thereof. Furthermore, within the scope of being able to solve at least a part of the above-mentioned problems or to achieve at least a part of the effects, any combination of the embodiments and modifications is possible, and any combination or omission of each component described in the claims and specification is possible. [Explanation of symbols]

[0024] 10...Impeller 12…Main plate 14…Side panel 20…Wing 22...Feather 24...Feather surface 241...1st straight line part 242…First curve part 26...wing surface 261…Second straight line part 262…Second curve part 20A…Feather-shaped blades 310...Base mold (base core) 320…Mold (core)

Claims

1. An impeller fixed to a rotating shaft of a turbo pump, A main plate and a side plate fixed to the rotating shaft; a blade portion disposed between the main plate and the side plate and having a plurality of spiral blades; Equipped with At the outer circumferential end of the plurality of blades, a blade surface facing the rotation direction has a first straight portion connected to the main plate and extending parallel to the rotation axis, and a first curved portion connected to the side plate and continuing to the first straight portion, and is smoothly inclined; a blade surface facing away from the rotation direction has a second straight line portion connected to the side plate and extending parallel to the rotation axis, and a second curved line portion connected to the main plate and continuing to the second straight line portion, the second curved line portion being smoothly inclined in the same direction as the first curved line portion. Impeller.

2. The impeller according to claim 1 , wherein the first curved portion and the second curved portion have the same length in the circumferential direction.

3. The impeller of claim 1 , wherein the first curvilinear portion and the second curvilinear portion have the same shape.

4. The impeller according to claim 1 , wherein each of the first curved portion and the second curved portion is configured to have a curved shape with a constant curvature.

5. A manufacturing method for manufacturing the impeller according to claim 1, comprising the steps of: preparing a vane mold simulating a plurality of vanes, each of which has an outer peripheral end extending parallel to a rotation axis from a main plate side to a side plate side; forming a base mold using the vane mold; forming a mold by cutting portions of the base mold corresponding to the first curved portion and the second curved portion; casting the impeller using the mold; A method for manufacturing an impeller, comprising:

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