Pump casing and pump equipped with same

Abstract

To provide a casing for a pump which enables reduction of an interference of the entire casing and a fastening force of the casing while securing a proper seal surface pressure of a rubber liner.SOLUTION: A rubber liner 50 includes a front liner 51 and a back liner 52. The casing 10 includes: a front casing 11 which covers the front liner 51; and a back casing 12 which covers the back liner 52. A flange part 11f of the front casing 11 and a flange part 12f of the back casing 12 have a compression holding structure which compressively holds a seal surface 50s of the rubber liner 50 between fastening surfaces 11m, 12m. Projections 11t, 12t for increasing the seal surface pressure are formed continuously on the respective fastening surfaces 11m, 12m.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pump having a split casing with a split rubber liner installed therein, and more particularly to a casing structure suitable for this type of pump. [Background technology]

[0002] This type of pump, as shown in Figure 5(a), comprises a casing 110 fitted with a rubber liner 150, and an impeller 130 supported on the tip of a shaft 120 protruding into the casing 110, with a storage space for the impeller 130 defined inside the rubber liner 150 (see, for example, Patent Document 1). In this type of pump, the rubber liner 150 and the casing 110 are known to be divided into two halves in the axial direction, front and rear. The use of a split casing 110 and a split rubber liner 150 improves the maintainability of the pump.

[0003] 5(a), the split rubber liner 150 includes a front liner 151 on the axial front side and a back liner 152 on the axial rear side. The split casing 110 includes a front casing 111 that covers the front liner 151 and a back casing 112 that covers the back liner 152. The front casing 111 and the back casing 112 have a plurality of fastening portions 170 at positions spaced apart in the circumferential direction, and the flange portions 151f, 152f of the two rubber liners 151, 152 are clamped from the front and rear by the fastening portions 170 with fastening bolts and nuts 172 between the fastening surface 111m of the flange portion 111f of the front casing 111 and the fastening surface 112m of the flange portion 112f of the back casing 112, and are fixed to each other. As a result, the split rubber liner 150 is held in the axial center within the casing 110 with the flange portions 151f, 152f being compressed together as a whole, demonstrating sealing performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-122402 Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of pump, in order to prevent liquid leakage from the mating surfaces (i.e., sealing surfaces) 150s of the flange portions 151f, 152f of the split rubber liner 150, the flange portions 151f, 152f on the outer periphery of the two rubber liners are fastened to the fastening surfaces 111m, 112m of the split casing 110 from the front and rear in the axial direction by fastening bolts and nuts 172 at fastening portions 170 with a predetermined torque to obtain an appropriate sealing surface pressure. In the past, as shown in Figure 1(a), flange portions 151f, 152f on the outer peripheries of the two front and rear rubber liners were fastened over the entire surfaces of the fastening surfaces 111m, 112m of the two front and rear casings 111, 112. However, the higher the rubber hardness of the rubber liner 150, the greater the fastening reaction force. Therefore, when the rubber hardness is high, the casing 110 needs to be fastened with a greater force.

[0006] On the other hand, if the rubber hardness is low, the pressing force will be small, but an increase in the internal pressure of the pump will make it easier for fluid to leak from the mating surface 150s of the flange portions 151f and 152f of the rubber liner 150. In particular, when the internal pressure of the pump becomes higher, as shown in Figures 11(b) and 11(c), the flange portions 151f and 152f of the rubber liner 150 will protrude significantly outward from the mating surface 150s, resulting in insufficient sealing surface pressure and fluid leakage.

[0007] Therefore, the present invention has been made with an eye on such problems, and its object is to provide a pump casing that can reduce the interference of the entire casing and the tightening force of the casing while ensuring an appropriate sealing surface pressure of the split rubber liner. [Means for solving the problem]

[0008] In order to solve the above problems, a pump casing according to one embodiment of the present invention is used in a pump in which a split rubber liner is installed and an impeller is supported on the tip of a shaft that protrudes inside the casing, thereby defining an accommodation space for the impeller inside the casing, and the split rubber liner is configured to include a front liner on the axial front side and a back liner on the axial rear side, and the casing itself is configured to include a front casing that covers the front liner and a back casing that covers the back liner, and has a clamping and holding structure that clamps and holds the sealing surfaces formed by the opposing rear surface of the flange portion of the front liner and the front surface of the flange portion of the back liner between the fastening surfaces of the flange portions of the front casing and the back casing by tightening them with bolts and nuts from the front and back in the axial direction, and the clamping and holding structure is characterized in that protrusions or steps for increasing sealing surface pressure are continuously formed on the fastening surface of at least one of the flange portions of the front casing and the flange portion of the back casing.

[0009] In a pump casing according to one aspect of the present invention, a flange portion on the outer periphery of the split casing has a continuous protrusion (protruding rib portion) or step portion formed on the sealing surface of the split rubber liner. This allows the necessary interference to be maintained at the top of the protrusion or step portion while reducing the overall interference of the flange portion on the outer periphery of the rubber liner. Therefore, with a pump casing according to one aspect of the present invention, the overall interference can be reduced while ensuring appropriate sealing surface pressure, significantly reducing the tightening force. Furthermore, the protrusion (protruding rib portion) or step portion is expected to prevent or suppress outward bulging of the flange portion of the rubber liner. Here, in a pump casing according to one embodiment of the present invention, it is preferable that the outer surface of the flange portion of the split rubber liner is covered by a cover portion with the outer edge of at least one of the flange portions of the front casing and the flange portion of the back casing.

[0010] In addition, in order to solve the above-mentioned problems, a pump casing according to another embodiment of the present invention is used in a pump in which a split rubber liner is installed and an impeller is supported on the tip of a shaft that protrudes inside the casing, thereby defining an accommodation space for the impeller inside the split rubber liner, the split rubber liner including a front liner on the axial front side and a back liner on the axial rear side, and the casing itself is a split casing including a front casing that covers the front liner and a back casing that covers the back liner, and is provided with a clamping and holding structure that clamps and holds the sealing surfaces formed by the opposing rear surface of the flange portion of the front liner and the front surface of the flange portion of the back liner between the fastening surfaces of the flange portions of the front casing and the back casing with bolts and nuts from the front and back in the axial direction, and the clamping and holding structure is characterized in that it has a covering portion that covers the outer peripheral surfaces of the flange portions of the two front and rear rubber liners with the outer edge of at least one of the flange portions of the front casing flange and the flange portion of the back casing flange.

[0011] In a pump casing according to another aspect of the present invention, the cover presses the outer peripheral surface of the flange of the split rubber liner, preventing or suppressing the flange of the rubber liner from bulging outward beyond the cover, even if the rubber liner is made of soft rubber. This is excellent for maintaining an appropriate seal surface pressure. This allows the interference of the entire casing and the tightening force of the casing to be reduced while ensuring an appropriate seal surface pressure of the split rubber liner.

[0012] The clamping structure of the present invention is provided with both a protrusion or step portion for increasing the sealing surface pressure and a cover portion, and the combined effect of these makes it possible to ensure sufficient pressure resistance even when the casing is tightened with a light force. It is also preferable that an arbitrary clearance is provided between the mating surfaces of the two front and rear casings, so that the tightening force can be adjusted according to the pressure resistance. [Effects of the Invention]

[0013] As described above, according to the present invention, it is possible to reduce the interference of the entire casing and the tightening force of the casing while ensuring an appropriate sealing surface pressure of the split rubber liner. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram of a centrifugal pump, which is one embodiment of a pump including a pump casing according to one aspect of the present invention, and shows a cross section along the axis. [Figure 2] 2A and 2B are explanatory views of the main part of the pump casing shown in FIG. 1, in which FIG. 2A is a ZZ cross-sectional view in FIG. 1, and FIG. 2B is an OEF cross-sectional view in FIG. [Figure 3] 10A and 10B are diagrams illustrating a modified example (first modified example) of the clamping and holding structure of the pump casing. [Figure 4] 10A and 10B are diagrams illustrating a modified example (second modified example) of the clamping and holding structure of the pump casing. [Figure 5] The figures are explanatory diagrams of an example of a pump equipped with a conventional pump casing, in which (a) shows a cross section of the main part along the axis, and (b) and (c) show images of the state in which the flange part of the rubber liner is deformed due to an increase in the internal pressure of the pump (indicated by the arrow in the figure). DETAILED DESCRIPTION OF THE INVENTION

[0015] 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 drawings also include portions where the relationship and ratio of dimensions differ from each other. Furthermore, the embodiments described below are intended to exemplify devices and methods for embodying the technical ideas of the present invention, and the technical ideas of the present invention do not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0016] As shown in FIG. 1, the centrifugal pump of this embodiment comprises a housing 40, a casing 10 provided in front of the housing 40, an impeller 30 supported on the tip of a shaft 20 protruding into the casing 10, an expeller 35 provided behind the impeller 30, and a seal ring type shaft seal section 60 provided behind the expeller 35.

[0017] The impeller 30 is cantilevered in the space within the casing 10. The impeller 30 of this embodiment has a plurality of blades 30a on its front surface and a plurality of rear blades 30b on its rear surface. The front surface of the casing 10 defines a suction side 10in that juts out forward along the axial direction, and the upper center defines a discharge side 10out. The base end side of shaft (rotating shaft) 20 penetrates the rear of casing 10 and extends into housing 40. A journal support 42 having two bearings 42a, 42b spaced apart in the axial direction is provided inside housing 40, and the base end side of shaft 20 is supported horizontally and rotatably by journal support 42. An output shaft of a motor (not shown) is connected to the rear end of shaft 20 so as to transmit driving force.

[0018] In the centrifugal pump of this embodiment, a highly wear-resistant rubber liner 50 is attached to cover the liquid-contacting portion of the inner circumferential surface of the casing 10. The liner 50 of this embodiment is configured so as to be separable into two halves approximately in the center along a plane perpendicular to the shaft 20, and is configured to include a front liner 51 on the axial front side and a back liner 52 on the axial rear side. In addition, the casing 10 of this embodiment is a split type that is split in two approximately in the middle along a plane perpendicular to the shaft 20, and is composed of a front casing 11 that covers the front liner 51 and a back casing 12 that covers the back liner 52.

[0019] The back surface of the back casing 12 is fixed to the front surface of the housing 40 with fixing bolts and nuts 82. The front casing 11 is fixed to the front surface of the back casing 12 with the front liner 51 and the back liner 52 sandwiched between them and the front surface of the back casing 12 with the bolts and nuts 72 of the fastening portion 70. This defines an accommodation space for the impeller 30 inside the liner 50. In the centrifugal pump of this embodiment, the fastening portions 70 are provided at four locations spaced apart from each other in the circumferential direction, as shown in FIG.

[0020] As shown in an enlarged view of the essential parts in Figure 2(b), the centrifugal pump of this embodiment has a clamping and holding structure in which a sealing surface 50s formed by the opposing rear surface of the flange portion 51f of the front liner 51 and the front surface of the flange portion 52f of the back liner 52 is clamped and held between the fastening surface 11m of the flange portion 11f of the front casing 11 and the fastening surface 12m of the flange portion 12f of the back casing 12 by bolts and nuts 72 of the fastening parts 70 from the front and rear in the axial direction. In the clamping and holding structure of this embodiment, protrusions 11t, 12t for increasing the sealing surface pressure are formed continuously along the sealing surface 50s on the fastening surfaces 11m and 12m of both the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12.

[0021] The radial formation position of the protrusions 11t, 12t can be any position in the width direction (short direction) of the clamping surfaces 11m and 12m as long as the sealing surface 50s can be clamped and held in place, but it is preferable to form them along the inner edges of the clamping surfaces 11m and 12m, which are closer to the flow path. Furthermore, the radial formation positions of the protrusions 11t and 12t can be any position in the width direction (short direction) of the sealing surface 50s as long as they can tighten and hold the sealing surface 50s, but it is preferable to form them along a position as close as possible to the inner edge of the sealing surface 50s, which is closer to the flow path.

[0022] In this embodiment, protrusions 11t and 12t are formed along the inner edges of the fastening surfaces 11m and 12m at positions as close as possible to the inner edge of the seal surface 50s, and at positions facing each other in the axial direction. The protrusions (11t or 12t) for increasing the seal surface pressure can be provided on at least one of the fastening surfaces 11m and 12m. Furthermore, the clamping and holding structure of this embodiment has cover portions 11c and 12c that cover the outer peripheral surfaces of the flange portions 51f and 52f of the two rubber liners 51 and 52 with the outer edges of the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12. The cover portion (11c or 12c) can be provided on the outer edge of at least one of the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12.

[0023] In this embodiment, the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12 are each formed with cover portions 11c, 12c facing each other at the front and rear of the axial direction so as to surround the outer peripheral surfaces 51t, 52t of the sealing surface 50s of the rubber liner 50. When the pump is not operating, a radial gap is provided between the outer peripheral surface 51t of the flange portion 51f and the cover portion 11c, and similarly, a radial gap is provided between the outer peripheral surface 52t of the flange portion 52f and the cover portion 12c. Between the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12, in this embodiment between the opposing cover portions 11c and 12c, a gap is provided that allows the axial opposing distance to be adjusted when the sealing surface 50s of the rubber liner 50 is clamped and held.

[0024] Next, the operation and effects of the centrifugal pump of this embodiment will be described. In the centrifugal pump of this embodiment, the impeller 30 is rotated to increase the pressure of the fluid being pumped, and the fluid is transferred from the suction side 10in of the casing 1 to the discharge side 10out. In conventional centrifugal pumps, such as slurry pumps, flange portions 151f and 152f on the outer peripheries of the two front and rear rubber liners are fastened over the entire fastening surfaces 111m and 112m of flange portions 111f and 112f of the two front and rear casings 111 and 112, as in the centrifugal pump shown in FIG.

[0025] However, as mentioned above, the higher the rubber hardness of the rubber liner 150, the greater the tightening reaction force, so if the rubber hardness is high, it is necessary to tighten the casing 110 with greater force. On the other hand, if the rubber hardness is low, the pressing force will be smaller, but an increase in the pump internal pressure will make it more likely that liquid will leak from the mating surface 150s of the rubber liner 150, which is in contact with the flange portions 151f and 152f.

[0026] In contrast to this, in the centrifugal pump of this embodiment, as shown in FIG. 2(b), the fastening surfaces 11m, 12m of the flange portions 11f, 12f on the outer periphery of the split-type casing 10 are provided with continuous protrusions (convex rib portions) 11t, 12t that run along the sealing surface 50s of the rubber liner 50. This makes it possible to reduce the overall interference of the flange portions 51f, 52f on the outer periphery of the rubber liner 50 while maintaining the necessary interference by pressing the topmost portions of the protrusions 11t, 12t. Therefore, according to the casing 10 of this embodiment, it is possible to reduce the interference of the entire casing 10 while ensuring an appropriate sealing surface pressure of the rubber liner 50, and to significantly reduce the tightening force of the casing 10. Furthermore, it is expected that the protrusions (convex rib portions) 11t, 12t will prevent or suppress the flange portions 51f, 52f of the rubber liners 51, 52 from bulging outward.

[0027] In addition, in the casing 10 of this embodiment, covering portions 11c, 12c are provided that cover the outer peripheral surfaces 51t, 52t of the flange portions 51f, 52f of the two rubber liners 51, 52 with the outer edges of at least one of the flange portions 11f of the front casing 11 and the flange portion 12f of the back casing 12 (both in this embodiment). As a result, according to the casing 10 of this embodiment, the cover portions 11c, 12c press against the outer peripheral surfaces of the flange portions 51f, 52f of the rubber liners 51, 52, thereby preventing or suppressing the flange portions 51f, 52f of the rubber liner 50 from bulging outward beyond the cover portions 11c, 12c, even if the rubber liner 50 is made of soft rubber. Therefore, the casing 10 of this embodiment is excellent in maintaining an appropriate seal surface pressure. As a result, the interference of the entire casing 10 and the tightening force of the casing 10 can be reduced while ensuring an appropriate seal surface pressure of the rubber liner 50.

[0028] In particular, in the casing 10 of this embodiment, as shown in Figure 2(b), when the pump is not in operation, a radial opposing gap is provided between the outer peripheral surface 51t of the flange portion 51f and the cover portion 11c, and a radial opposing gap is provided between the outer peripheral surface 52t of the flange portion 52f and the cover portion 12c. This intentionally allows the flange portions 51f, 52f of the rubber liner 50 to initially deform when they bulge outward, thereby preventing them from bulging radially inward during deformation and disrupting the flow. In other words, if there is no opposing gap and no escape route is secured for the volume occupied by the rubber crushing allowance, there is a risk that they will bulge radially inward during deformation, disrupting the flow.

[0029] As described above, the pump casing of this embodiment makes it possible to reduce the interference of the entire casing 10 and the tightening force of the casing 10 while ensuring an appropriate sealing surface pressure of the rubber liner 50. The pump casing according to the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, as a clamping and holding structure, continuous protrusions (convex rib portions) 11t, 12t are provided on the fastening surfaces 11m, 12m along the sealing surface 50s of the rubber liner 50, and cover portions 11c, 12c that cover the outer peripheral surfaces 51t, 52t of the flange portions of the rubber liner 50 are provided on the outer edges of the flange portions 11f, 12f, but this is not limited to this.

[0030] For example, the clamping and holding structure may be provided with either protrusions (protruding portions) 11t, 12t that continue along the sealing surface 50s of the rubber liner 50, or covering portions 11c, 12c that cover the outer peripheral surfaces 51t, 52t of the flange portions of the rubber liner 50. 3, for example, the clamping and holding structure is an example in which only cover portions 11c and 12c are provided to cover the outer peripheral surfaces 51t and 52t of the flange portion of the rubber liner 50. As in the above embodiment, a gap T is provided between the opposing cover portions 11c and 12c, which allows the axial opposing distance to be adjusted when the sealing surface 50s of the rubber liner 50 is clamped and held.

[0031] Furthermore, in the above embodiment, the protrusions 11t, 12t are formed continuously along the seal surface 50s as a clamping and holding structure for increasing the seal surface pressure, but this is not limited to this. For example, as shown in another modified example in FIG. 4, as a clamping and holding structure, steps 11d, 12d that become recessed ridges on the inner circumferential side may be formed continuously along the seal surface 50s on at least one of the opposing surfaces of the flange portion 11f of the front casing 11 and the flange portion 12f of the back casing 12.

[0032] In the example shown in the figure, steps 11d and 12d are provided on both flanges 11f and 12f. With this configuration, a localized clamping pressure holding structure is created by the step between steps 11d and 12d, which form grooves on the inner periphery, and the outer periphery, so that sufficient pressure resistance can be ensured even when the casing 10 is tightened with a light force by increasing the sealing surface pressure. However, by providing the clamping and holding structure with both protrusions 11t, 12t or step portions 11d, 12d for increasing the sealing surface pressure, and cover portions 11c, 12c, the combined effect of these makes it possible to ensure sufficient pressure resistance even when the casing 10 is tightened with a light force. [Explanation of symbols]

[0033] 10 Casing 10in suction side 10out discharge side 11 Front casing 11f (Front casing) flange 11m (Front casing) fastening surface 11c Cover 11t protrusion 12 Back casing 12f (Back casing) flange 11m (Back casing) fastening surface 12c Cover 12t protrusion 20 Shaft (rotating axis) 30 impeller 30a feather 30b back feather 35 expeller 40 Housing 42 axis branch 50 Liner 51 Frontliner 51f (Front liner) flange 52 Backliner 52f (Backliner) flange 50s sealing surface 60 Shaft seal 70 Fastening part 72 Fastening bolts and nuts 82 Fixing bolts and nuts

Claims

1. A split rubber liner is installed inside the pump, and an impeller is supported on the tip of a shaft protruding into the pump, so that an accommodating space for the impeller is defined inside the split rubber liner. The split rubber liner includes a front liner on the axial front side and a back liner on the axial rear side. The split casing itself includes a front casing that covers the front liner and a back casing that covers the back liner. a clamping and holding structure for clamping and holding a sealing surface formed by the rear surface of the flange portion of the front liner and the front surface of the flange portion of the back liner, between the fastening surfaces of the flange portion of the front casing and the flange portion of the back casing, by fastening fastening portions that the front casing and the back casing respectively have with bolts and nuts from the front and rear in the axial direction, The bolt of the bolt-nut assembly has a bolt large diameter portion formed in a longitudinal center portion thereof with a larger diameter than other portions thereof, and is disposed between the fastening portion of the front casing and the fastening portion of the back casing with an opposing gap formed in the axial direction, The nuts of the bolt-nut assembly are two nuts attached to both ends of the bolt, The clamping and holding structure is a projection or a step portion for increasing a sealing surface pressure is continuously formed on the fastening surface of at least one of the flange portion of the front casing and the flange portion of the back casing; The bolt further includes two cover portions that are disposed closer to the flange portion of the split rubber liner than the large diameter portion of the bolt and that cover the outer peripheral surface of the flange portion of the split rubber liner with the outer edges of the flange portion of the front casing and the flange portion of the back casing, The two cover portions protrude axially more than other portions on the surface of the front casing facing the back casing and on the surface of the back casing facing the front casing, and have an axial opposing gap between them.

2. 2. The pump casing according to claim 1, wherein when the pump is not operating, a radial gap is provided between the outer peripheral surface of the flange portion of the split rubber liner and the cover portion.

3. an outer edge of a flange portion of the front casing and an outer edge of a flange portion of the back casing are formed opposite to each other at the front and rear in the axial direction so as to surround an outer periphery of the sealing surface of the split rubber liner, 3. A pump casing as described in claim 1 or 2, wherein a gap is provided between the outer edge of the flange portion of the front casing and the outer edge of the flange portion of the back casing, such that the axial opposing distance can be adjusted when the sealing surface of the split rubber liner is clamped and held.

4. A pump comprising: a split casing in which a split rubber liner is installed; and an impeller supported on a tip of a shaft protruding into the split casing, wherein an accommodation space for the impeller is defined inside the split rubber liner, A pump comprising the pump casing according to any one of claims 1 to 3 as the split casing.

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