centrifugal pump

Abstract

To provide a centrifugal pump that is improved in maintainability.SOLUTION: A centrifugal pump 1 includes: an impeller 10; and a casing 2 for accommodating the impeller 10. The casing 2 has a circular shape or elliptical shape when being viewed from an axial direction of a drive shaft 3 of the impeller 10. The casing 2 has a center CL2 which is not coaxial with a center CL1 of the drive shaft 3 of the impeller 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a centrifugal pump having a liner structure in a liquid-contacting portion. [Background technology]

[0002] Among centrifugal pumps, slurry pumps that transport slurry containing a high concentration of solids in the liquid require frequent part replacement because the inner surface of the casing that comes into contact with the liquid is subject to wear and corrosion.For this reason, by providing a liner structure on the liquid-contacting part, running costs are reduced and resources are saved. More specifically, this type of centrifugal pump includes an impeller with multiple blades and a casing with a front casing and a back casing. The impeller is housed in a space defined by the front casing and the back casing. A highly wear-resistant liner is provided on the inner surface of the casing.

[0003] Because the impeller is installed in a defined space within the casing, the liner and casing have a split structure, being divided into multiple parts. In particular, the liner, which is split into multiple parts, includes a front liner that serves as the suction port of the front casing. This allows the liner, which has excellent wear resistance, to be placed inside the casing, allowing the centrifugal pump to be operated for a long period of time by replacing only the liner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2007-533886 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the liners are divided into multiple segments and are made of a hard material with excellent wear resistance, it is difficult to thread the liners, and providing screws to the liners to secure the divided liners inside the casing is undesirable from the standpoint of quality and cost. Therefore, the divided liners are not provided with screws themselves, but are held together by the casing that surrounds them in an assembled state.

[0006] However, because this type of centrifugal pump has a complex liner structure in the liquid-contacting parts, shortening the time required for disassembly and assembly significantly affects maintainability. Furthermore, many conventional centrifugal pumps, not just slurry pumps, have a structure in which the divided surfaces of the casing 202 are fastened together with bolts and nuts 241 and 242, as in the centrifugal pump 200 shown in Figure 5. The same is true for the suction port 204 and discharge port 205 of the casing 202.

[0007] In contrast to this, an example having a clamp-type fastening structure is shown in Fig. 6. As in the centrifugal pump 100 shown in the figure, there are pumps that employ clamp-type fastening structures 141, 142, 143, and 144 for a casing 102. In this centrifugal pump 100, a housing (bearing box) 107 that rotatably supports a drive shaft 103 is provided on a base 120, and a casing 102 is detachably mounted on the front of the housing 107 by clamp-type fastening structures 141, 142, 143, and 144. With this configuration, the time required for disassembling and assembling the casing 102 can be reduced, improving maintainability. However, the liquid-contacting portion of the casing 102 shown in the figure is a single casing without a liner structure, so there is room for further consideration before applying it to a centrifugal pump that has a liner structure in the liquid-contacting portion.

[0008] Here, when a clamp-type fastening structure is adopted to improve maintainability for a casing 202 having a liner structure 230 having multiple liners 231, 232, and 233 in the liquid-contacting portion as shown in Figure 5(b), since the conventional casing 202 has a simple spiral shape as shown in the oblique view of the same Figure (a), when considering incorporating the liners 231, 232, and 233 into the liquid-contacting portion of the casing 202, it is extremely difficult to manufacture a casing and gasket having a clamp-type fastening structure that does not cause water leakage.

[0009] The present invention has been made in light of these problems, and it is an object of the present invention to provide a centrifugal pump having a liner structure in the liquid-contacting part of the casing, which has improved maintainability and allows the disassembly and assembly of the casing to be performed more safely and smoothly. [Means for solving the problem]

[0010] In order to solve the above problems, one aspect of the present invention provides a centrifugal pump comprising an impeller and a casing that houses the impeller, wherein the casing has a front casing on the front side and a back casing on the rear side that are divided along a plane perpendicular to the drive shaft of the impeller, and is formed into a circular or elliptical shape when viewed from the axial direction of the drive shaft of the impeller, and the center of the circle or ellipse is not coaxial with the drive shaft of the impeller.

[0011] In a centrifugal pump according to one aspect of the present invention, the center of the casing is not coaxial with the drive shaft of the impeller, so the suction port or discharge port of the casing and the suction part of the impeller can be located at positions axially opposite to the drive shaft. Therefore, even when applied to a centrifugal pump with a liner structure, a clamp-type fastening structure can be used, improving maintainability.

[0012] In the centrifugal pump according to one aspect of the present invention, it is preferable that the casing has a clamp-type fastening structure at the dividing surface between the front casing and the back casing, at the connection part of the suction port, or at the connection part of the discharge port. Such a configuration is suitable for improving maintainability in a centrifugal pump having a liner structure.

[0013] In the centrifugal pump according to one aspect of the present invention, the casing preferably has a double casing structure with a liner in the liquid-contacting portion of the inner surface of the casing, which is advantageous in terms of improving maintainability in a centrifugal pump with a liner structure.

[0014] In the centrifugal pump according to one aspect of the present invention, it is preferable that the suction port or the discharge port of the casing and the suction portion of the impeller are provided at positions that face each other in the axial direction of the drive shaft. This configuration is more suitable for employing a clamp-type fastening structure to improve maintainability. [Effects of the Invention]

[0015] As described above, according to the present invention, the ease of maintenance is improved. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic plan view illustrating an embodiment of a centrifugal pump according to an aspect of the present invention. FIG. [Figure 2] FIG. 2 is a diagram illustrating a casing portion of the centrifugal pump of FIG. 1, showing a cross section along the axis (YY cross section of FIG. 1). [Figure 3] 2. FIG. 2 is a cross-sectional view of the casing portion taken along the line XX. [Figure 4] 1A to 1C are diagrams (a) to (c) illustrating modified examples of the casing portion of a centrifugal pump according to one embodiment of the present invention, in which FIG. 1A is an example of a rear suction and rear discharge type, FIG. 1B is an example of a front suction and rear discharge type, and FIG. 1C is an example of a front suction and front discharge type. [Figure 5] 1A and 1B are diagrams illustrating an example of a centrifugal pump having a conventional fastening structure and a liner, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view taken along the axis of the drive shaft. [Figure 6] FIG. 1 is a schematic perspective view illustrating an example of a centrifugal pump having a casing with a conventional clamp-type fastening structure that does not have a liner in the liquid-contacting portion. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc. differ from the actual ones, and the dimensional relationships and ratios between the drawings may differ. Furthermore, the embodiments described below are intended to exemplify devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0018] 1 to 3 show an embodiment of a centrifugal pump according to the present invention. The centrifugal pump of this embodiment has a liner structure in the liquid-contacting portion and is equipped with a casing with a clamp-type fastening structure. 1, the centrifugal pump 1 of this embodiment includes a housing (bearing housing) 7 that rotatably supports a drive shaft 3, a suction cover 6, and a casing 2. The drive shaft 3 protrudes rearward from the rear end of the housing 7, and this protruding portion is connected to an output shaft 24 of a motor 23 via a belt transmission mechanism 22 so as to transmit driving force.

[0019] As shown in a vertical cross section of the casing 2 in FIG. 2, the centrifugal pump 1 of this embodiment includes a casing 2 having a split liner 30 provided on the inner surface thereof as a liquid-contacting portion. The casing 2 is divided into two parts along a plane perpendicular to the drive shaft 3, and has a front casing 8 on the axial front side (left side in the figure) and a back casing 9 on the axial back side (right side in the figure). The front casing 8 and the back casing 9 are detachably fixed around the periphery of the divided surface using a clamp-type fastening structure (for example, a one-touch clamp mechanism (for example, a ferrule clamp)).

[0020] The tip 3s of the drive shaft 3 protrudes from the center of the back casing 9 into the inside of the casing 2. An impeller 10 is cantilevered on the tip 3s of the drive shaft 3. The area surrounding the tip 3s of the drive shaft 3 forms the suction portion 10a of the impeller 10. The suction portion 10a of the impeller 10 is located at a position opposite to the drive shaft 3 in the axial direction. A shaft seal device 21 is disposed between the back casing 9 and the housing 20 on the axial rear side of the impeller 10 so as to surround the drive shaft 3. A cheese-shaped suction cover 6 is provided in the center of the back casing 9 so as to protrude toward the rear side of the back casing 9.

[0021] The suction cover 6 is provided with a suction port 4 at the same height as the axis CL1 of the drive shaft 3 of the impeller 10 and protruding in a direction perpendicular to the drive shaft 3. On the axial front side of the impeller 10, at the center of the upper part in the radial direction of the front casing 8, there is a discharge port 5 having a cylindrical inner surface, the axis CL3 of which is aligned with the axis CL1 of the drive shaft 3. flat The openings are formed in rows at positions facing the drive shaft 3 in the axial direction. On the back side of the suction cover 6, a housing 7 is placed and fixed on a base frame 20. The back side of a back casing 9 is fixed to the front side surface of the suction cover 6. Within the housing 7, the drive shaft 3 is supported with its axis horizontal by a bearing (not shown).

[0022] In the centrifugal pump 1 of this embodiment, the drive shaft 3 is driven by the motor 23 via the belt transmission mechanism 22, causing the impeller 10 to rotate in the desired direction, thereby sucking in a fluid such as slurry through the suction port 4 and discharging the fluid from the discharge port 5. The split-type liner 30 is made of a material with excellent wear resistance, and has a front liner 31 that is the liquid-contacting portion on the inner surface of the front casing 8 and covers the liquid-contacting portion on the front side of the casing 2, and a back liner 32 that is the liquid-contacting portion on the inner surface of the back casing 9 and covers the liquid-contacting portion on the back side of the casing 2. The front liner 31 and the back liner 32 are detachable along the axial direction of the drive shaft 3.

[0023] The suction cover 6 is lined with a rubber cover lining 33 so as to cover the liquid-contacting portion of its inner circumferential surface. An annular rubber packing 35 is fitted to the connection portion of the front liner 31 on the discharge port 5 side. An annular rubber packing 36 is fitted to the connection portion of the back liner 32 on the suction port 4 side. The divided liners 30 are not provided with screws themselves, but are held together by the casing 2 and suction cover 6 that surround the liners 30 when assembled as shown in Figure 2. The front and rear of the cover lining 33 are also fixed around its periphery using one-touch clamping mechanisms (e.g., ferrule clamps) 41, 42.

[0024] The centrifugal pump 1 according to this embodiment has the following structural features. First, when the casing 2 is viewed from the front (in the axial direction of the drive shaft 3 of the impeller 10), a typical centrifugal pump has a volute-shaped casing as shown in Fig. 5(a). In contrast, when the centrifugal pump 1 of this embodiment has a casing 2 viewed from the front (in the axial direction of the drive shaft 3 of the impeller 10), the shape is a simple circle (or ellipse), as shown in Fig. 3.

[0025] Second, the centrifugal pump 1 of this embodiment is a non-coaxial type in which the center CL2 of the circular casing 2 is eccentric with respect to the center CL1 of the drive shaft 3, and the center CL2 of the casing 2 and the center CL1 of the drive shaft 3 of the impeller 10 are not coaxial. As shown in the figure, although this embodiment is a non-coaxial centrifugal pump, the flow path of the pumped fluid is formed so as to describe a smooth involute curve. Thirdly, in the centrifugal pump 1 according to this embodiment, when viewed from the side (perpendicular to the axis CL1 of the drive shaft 3 of the impeller 10), as shown in FIG. 2, the front liner 31 and the back liner 32 can be inserted and removed along the axial direction from the plane that divides the casing 2 into two (the plane that is perpendicular to the axis CL1 of the drive shaft 3).

[0026] Fourth, in a conventional centrifugal pump 200 shown in FIG. 5, the axis of the discharge port 205 is perpendicular to the drive shaft 203 of the impeller 210, whereas in the centrifugal pump 1 of this embodiment, the axis CL1 of the drive shaft 3 of the impeller 10 and the axis CL3 of the discharge port 5 are parallel to each other. Fifth, in the centrifugal pump 1 of this embodiment, the suction port 4 of the casing 2 and the suction portion 10a of the impeller 10 are located on the drive shaft 3 side. By combining these structural features, the centrifugal pump 1 of this embodiment can achieve both a clamp-type fastening structure and a liner structure.

[0027] The centrifugal pump according to the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the centrifugal pump 1 in the above embodiment is shown as an example in which the shape of the casing 2 when viewed from the front (axial direction of the drive shaft 3 of the impeller 10) is a simple circle, but this is not limited to this, and the shape of the casing when viewed from the front (axial direction of the drive shaft 3 of the impeller 10) may also be elliptical.

[0028] Furthermore, in the centrifugal pump 1 of the above embodiment, the positions of the suction port 4 and the discharge port 5 of the casing 2 are an example of a rear suction / front discharge type, but this is not limited to this. For example, the positions of the suction port 4 and the discharge port 5 can be a rear suction / rear discharge type as shown in Figure 4(a), a front suction / rear discharge type as shown in Figure 4(b), or a front suction / front discharge type as shown in Figure 4(c).

[0029] The non-coaxial centrifugal pumps shown in the above embodiments and their modifications also improve maintainability. In particular, the non-coaxial centrifugal pump according to the present invention has a compact configuration as shown in the above embodiments and modifications, and can be adapted to various configurations. Although the non-coaxial centrifugal pump according to the present invention is suitable for a liner type, it is not limited to a liner type. Since the axial disassembly is significantly improved, the pump is suitable for applications such as an inline pump installed in the middle of a pipe (e.g., a boost pump). [Explanation of symbols]

[0030] 1. Centrifugal pump 2 Casing 3 drive shaft 4 Intake port 5 Outlet 6 Intake cover 7 Housing (bearing box) 8 Front casing 9 Back casing 10 Impeller 11 Main feather (feather) 20 base frame 21 Shaft sealing device 22 Belt transmission mechanism 23 Motor 24 output shaft 30 Liner 31 Frontliner 32 Backliner 33 Cover lining 40 One-touch clamp CL1 Axis of the impeller drive shaft CL2 Casing center axis CL3 Center axis of outlet

Claims

[Claim 1] A centrifugal pump comprising an impeller and a casing that houses the impeller, The casing has a double casing structure in which a liner that comes into contact with the liquid is replaceably fitted in the liquid-contacting portion of the inner surface of the casing, and further has a front casing on the front side and a back casing on the rear side that are divided into two along a plane perpendicular to the drive shaft of the impeller, and the liner is divided into a front liner fitted in the front casing and a back liner fitted in the back casing, and the front liner and the back liner are detachable from the front casing and the back casing, and the shape when viewed from the axial direction of the drive shaft of the impeller is formed to be circular or elliptical, and the centre of the circle or ellipse is not coaxial with the drive shaft of the impeller, The impeller is supported at a tip of the drive shaft of the impeller so that a main blade faces the drive shaft side of the impeller, a shaft seal device is disposed on the bearing housing side of the drive shaft of the impeller; The suction port of the casing is provided between the main blade of the impeller and the shaft seal device, A centrifugal pump characterized in that the discharge port of the casing is formed so that its axis is non-coaxial and parallel to the axis of the drive shaft of the impeller.

Images