Packing pressing member, shaft seal device for centrifugal pump, and centrifugal pump comprising the same

Abstract

To provide a packing pressing member that can uniformly press a ground packing, facilitates replacement of a ground packing and is excellent in maintainability, a shaft seal device for a centrifugal pump and a centrifugal pump comprising the same.SOLUTION: A packing pressing member 40 has an upper split body 41 and a lower split body 42, which are divided into two parts, and has a fastening parts 46 on the left and right sides. Each split body 41, 42 has a pressing cylindrical part 44 that protrudes from a base part 43 and presses a gland packing from the rear in an axial direction, and a rib 45 that protrudes so as to separate from the pressing cylindrical part 44 in a radial direction. A portion between the pressing cylindrical part 44 and the rib 45 forms a hollowed-out part 51 that does not interfere with a rear end of a stuffing box in the axial direction. The top and bottom centers of the base part 43 are opening parts 52, 53 without ribs, where the upper opening part 52 functions as a viewing window to visually check an amount of tightening, and the lower opening part 53 functions as a discharge window to discharge leaking liquid.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a centrifugal pump, and more particularly to a gland packing pressing structure for pressing the gland packing from the axial rear in a shaft seal device of a centrifugal pump. [Background technology]

[0002] A centrifugal pump includes a casing and an impeller supported on the tip of a drive shaft that protrudes into the casing. Depending on the specifications, a shaft seal device using a gland packing is provided at the rear of the impeller (see, for example, Patent Document 1). This type of shaft seal device comprises a stuffing box that is mounted coaxially with the drive shaft at the rear of the casing, and a packing pressing member that presses the gland packing housed in the stuffing box from the axial rear.

[0003] When the gland packing is installed, the gland packing is pressed from the axial rear by the packing pressing member, which generates a force that presses the gland packing against the surface of the drive shaft, and the contact pressure seals off any fluid leaking from inside the casing to the rear of the casing. However, in this type of shaft seal device, in order to cool and lubricate the gland packing, it is necessary to adjust the amount of pressure applied to the gland packing to allow a small amount of fluid to leak out and lubricate it, so the amount of pressure applied to the gland packing is adjusted by the packing pressure member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-140875 A (Figure 2, paragraphs 0004-0005) Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, the packing pressing member is either one-piece or U-shaped (horseshoe-shaped). However, when replacing the gland packing, if the packing pressing member is one-piece, the packing pressing member cannot be removed without disassembling the drive shaft. This makes it difficult to remove the gland packing.

[0006] On the other hand, if the packing pressing member is U-shaped as shown in Fig. 11, it can be removed without disassembling the drive shaft, but if it is simply a U-shaped packing pressing member, it presses only the U-shaped protrusion in the axial direction, so there is a problem that it cannot press the gland packing uniformly (evenly around 360° in the circumferential direction). Therefore, there is still a problem to be solved in stabilizing the amount of fluid leakage.

[0007] In contrast, if the packing pressing member is split into two parts, upper and lower, at the part surrounding the drive shaft as shown in Fig. 10, the packing pressing member can be removed without disassembling the drive shaft, and the pressing parts are evenly arranged over 360°, so the gland packing can be pressed evenly. Therefore, this is preferable as a packing pressing structure that presses the gland packing from the axial rear. However, when the packing pressing member has a split structure, a fastening portion is required to fix the split bodies together. Therefore, if the packing pressing member occupies a large space in the axial direction, the limited maintenance space becomes relatively narrow. Therefore, even when the packing pressing member has a split structure, there is still room for improvement in terms of compactness to secure a larger space for necessary maintenance work.

[0008] Therefore, the present invention has been made with attention to such problems, and it is an object of the present invention to provide a packing pressing member that can press the gland packing uniformly and easily replace the gland packing, and that is easy to maintain, a shaft seal device for a centrifugal pump, and a centrifugal pump equipped with the same. [Means for solving the problem]

[0009] In order to solve the above problems, a packing pressing member according to one aspect of the present invention is used in a shaft seal device provided at the rear of an impeller of a centrifugal pump, and presses a gland packing in a stuffing box of the shaft seal device from the axial rear, the packing pressing member having a two-part structure formed by combining one divided body that is divided vertically or obliquely with the other divided body, and including a base part having a base surface facing the rear end face of the stuffing box, and a pressing cylinder that protrudes cylindrically in the axial direction from the base surface of the base part toward the inside of the stuffing box and presses the gland packing from the axial rear The one split body and the other split body are configured in a state in which they are combined with each other, and the one split body and the other split body have a pair of bolt insertion holes formed axially through the base at positions radially outward from the pressing cylindrical portion so that they can be screwed into the rear end faces of the left and right stuffing boxes, a rib on the base that protrudes axially toward the stuffing box at a position radially outward from the pair of bolt insertion holes and does not interfere with the outer peripheral surface of the stuffing box, and a fastening portion provided on the rib for fastening the one split body to the other split body at a left-right or diagonal position.

[0010] In addition, in order to solve the above-mentioned problems, a packing pressing member according to another aspect of the present invention is a packing pressing member used in a shaft seal device provided at the rear of the impeller of a centrifugal pump, which presses a gland packing in a stuffing box of the shaft seal device from the axial rear, and has a two-part structure formed by combining one divided body with the other divided body, and includes a base having a base surface facing the rear end face of the stuffing box, a pressing cylindrical part that protrudes cylindrically in the axial direction from the base surface of the base toward the inside of the stuffing box and presses the gland packing from the axial rear, and a pair of bolt insertion holes formed through the base along the axial direction at positions radially outside the pressing cylindrical parts so that a pair of bolts can be fastened thereto. The one divided body and the other divided body are combined with each other in the radial or axial direction.

[0011] In order to solve the above problems, a shaft seal device for a centrifugal pump according to one embodiment of the present invention is a shaft seal device used in a centrifugal pump to lubricate while allowing a small amount of pressurized liquid to leak, and comprises a stuffing box provided at the rear of the impeller of the centrifugal pump, and a packing pressing member attached to the rear end face of the stuffing box and pressing a gland packing contained in the stuffing box from the axial rear, and the packing pressing member has a packing pressing member according to any one of the embodiments of the present invention.

[0012] In order to solve the above-mentioned problems, a centrifugal pump according to one aspect of the present invention includes a pump shaft seal device according to one aspect of the present invention.

[0013] The packing pressing member according to one aspect of the present invention has a two-piece structure formed by combining two separate parts. Therefore, when replacing the gland packing, the packing pressing member can be removed without disassembling the drive shaft, resulting in excellent maintainability. In addition, the pressing cylindrical portion protrudes cylindrically in the axial direction toward the stuffing box and can press the gland packing from the axial rear, and since the pressing portions are also evenly arranged 360° in the circumferential direction, the gland packing can be pressed uniformly. Effect of the Invention

[0014] As described above, according to the present invention, it is possible to provide a packing pressing member that can uniformly press the gland packing and facilitates replacement of the gland packing, and thus has excellent maintainability, a shaft seal device for a centrifugal pump, and a centrifugal pump equipped with the same. [Brief description of the drawings]

[0015] [Figure 1] 1 is an illustration of an embodiment of a centrifugal pump according to an aspect of the present invention, showing a cross section taken along the axis of the drive shaft. [Diagram 2] 1A to 1F are six-sided views of a first embodiment of a packing pressing member according to an aspect of the present invention. [Diagram 3]6A to 6F are six-sided views of a second embodiment of a packing pressing member according to an aspect of the present invention. [Figure 4] 6A to 6F are six-view diagrams ((a) to (f)) of a third embodiment of a packing pressing member according to an aspect of the present invention. [Diagram 5] 13A, 13B, 13C, and 13D are explanatory views of one of the divided bodies constituting a fourth embodiment of a packing pressing member according to one aspect of the present invention ((a) is a front view, (b) is a side view, (c) is a rear view, and (d) is a plan view). [Figure 6] 13A, 13B, 13C, and 13D are explanatory views of the other divided body constituting a fourth embodiment of a packing pressing member according to one aspect of the present invention ((a) is a front view, (b) is a side view, (c) is a rear view, and (d) is a plan view). [Figure 7] 13A to 13D are explanatory views of a split body constituting a fifth embodiment of a packing pressing member according to one aspect of the present invention ((b) is a front view, (a) is a side view, (c) is a rear view, and (d) is a plan view). [Figure 8] 13A and 13B are explanatory views of a process of assembling two split bodies constituting the packing pressing member of the fifth embodiment, in which FIG. 13A shows a state before assembly and FIG. 13B shows a state after assembly. [Figure 9] 13A and 13B are diagrams illustrating the process of assembling the packing pressing member of the fifth embodiment to the shaft seal device, in which (a) shows the two divided bodies facing each other radially, (b) shows the two divided bodies moved radially toward each other and combined, and (c) shows the two divided bodies in the combined state moved axially forward to a position where they can be screwed into the rear end face of the stuffing box. [Figure 10] 1A and 1B are explanatory views of a conventional split-type packing pressing member ((a) is a front view, and (b) is a side view). [Figure 11] 1A and 1B are explanatory views of a conventional U-shaped packing pressing member ((a) is a front view, and (b) is a side view). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 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. are different from the actual ones, and the drawings also include parts where the relationship and ratio of dimensions differ from each other. Furthermore, the embodiments described below are merely examples of 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.

[0017] 1, the centrifugal pump 1 of this embodiment includes a frame 10 and a casing 5 attached to the front end face of the frame 10. In the centrifugal pump 1 of this embodiment, an impeller 3 supported at one end of a drive shaft 2 protrudes from within the casing 5, and an expeller 4 is provided behind the impeller 3. The impeller 3 of this embodiment has a plurality of blades 3a on its front surface and a plurality of rear blades 3b on its back surface. The front surface of the casing 5 is the suction side 5in that protrudes forward along the axial direction, and the upper center is the discharge side 5out.

[0018] The base end side of the drive shaft 2 passes through the rear of the casing 5 and extends into the frame 10. A shaft support section 60 having two bearings 61, 62 spaced apart in the axial direction is provided inside the frame 10, and the base end side of the drive shaft 2 is supported horizontally and rotatably by this shaft support section 60. The front side of the bearing 61 is sealed by a seal section 20. A drive pulley, for example, is coaxially attached to the rear end section of the drive shaft 2, and the output of a motor (not shown) is connected to the drive shaft 2 so that it can be transmitted via a drive belt (not shown).

[0019] In the centrifugal pump of this embodiment, a liner 70 made of rubber with excellent wear resistance is attached so as to cover the liquid-contacting portion of the inner peripheral surface of the casing 5. The liner 70 of this embodiment is configured so as to be vertically split into two at approximately the center along a plane perpendicular to the drive shaft 2, and includes a front liner 71 on the axial front side and a back liner 72 on the axial rear side.

[0020] In addition, the casing 5 of this embodiment is a split type that is divided vertically in two at approximately the center along a plane perpendicular to the drive shaft 2, and is composed of a front casing 6 that covers the front liner 71, and a back casing 7 that covers the back liner 72. The front casing 6 is fixed to the front liner 71 and the back liner 72 by means of bolts and nuts 90 so that the front liner 71 and the back liner 72 are sandwiched between the front surface of the back casing 7 and the front casing 6. As a result, an accommodation space for the impeller 3 is defined inside the liner 70.

[0021] A gland packing type shaft seal device 30 is provided behind the expeller 4. The shaft seal device 30 includes a stuffing box 31 that houses a gland packing 32 therein, and a packing pressing member 40 that is attached to the rear end surface of the stuffing box 31 and presses the internal gland packing 32 from the axial rear. In particular, the packing pressing member 40 of this embodiment has a two-part structure that combines an upper divided body (one divided body) 41 and a lower divided body (the other divided body) 42 that are divided vertically (or diagonally) into two.

[0022] More specifically, as shown in a six-sided view in Fig. 2, the packing pressing member 40 of the first embodiment is configured by combining an upper division body 41 and a lower division body 42 in a radial direction. The upper division body 41 and the lower division body 42 each have a base portion 43 and a pressing cylindrical portion 44, which are configured in a cooperative state by combining them in a radial direction. The upper division body 41 and the lower division body 42 of this embodiment have the same shape. Furthermore, the upper division body 41 and the lower division body 42 are made of the same resin.

[0023] The base 43 of each of the divided bodies 41, 42 has a base surface 43b facing the rear end surface of the stuffing box 31. The pressing cylindrical portion 44 of each of the divided bodies 41, 42 protrudes cylindrically in the axial direction from the base surface 43b of the base 43 toward the inside of the stuffing box 31 and is capable of pressing the gland packing 32 from the axial rear over the entire circumference.

[0024] A pair of bolt insertion holes 47 are formed in the base 43 of each of the segments 41, 42 at left and right positions of a mating surface 48, penetrating the base 43 along the axial direction. The pair of bolt insertion holes 47 are formed at left and right radially outward of the pressing cylindrical portion 44, at positions where they can be screwed into the rear end surface 31r of the stuffing box 31, so that a pair of bolts and nuts 54 can be fastened. The base 43 is formed with a pressing portion 43g, which is a portion of the packing pressing member 40 (segments 41, 42) that is pressed by the bolt 54. In addition, a rib 45 is provided on the edge of the base 43 of each divided body 41, 42, protruding in the axial direction toward the stuffing box 31. The top and bottom of the base 43 are openings 52, 53 without ribs 45. The rib 45 is provided at a position radially outward of a pair of bolt insertion holes 47 with respect to the base 43 and does not interfere with the outer peripheral surface of the stuffing box 31. Fastening portions 46 are provided on the left and right sides of the outer surfaces of the ribs 45. The fastening portions 46 protrude to the left and right sides and are capable of fastening the upper divisional body 41 and the lower divisional body 42 to each other at left and right (or diagonal) positions.

[0025] Next, the effects of the packing pressing member 40, the centrifugal pump shaft seal device 30, and the centrifugal pump 1 including the same according to this embodiment will be described. As described above, the packing pressing member 40 of this embodiment has a two-piece structure in which an upper part 41 and a lower part 42, which are divided into two parts vertically (or diagonally), are combined radially. Therefore, when replacing the gland packing 32, the packing pressing member 40 can be removed without disassembling the drive shaft 2. In addition, the pressing cylindrical portion 44 protrudes cylindrically in the axial direction toward the inside of the stuffing box 31 and is capable of pressing the gland packing 32 from the axial rear over the entire circumference, and therefore the pressing surfaces 44m are also evenly arranged 360° in the circumferential direction, so that the gland packing 32 can be pressed uniformly.

[0026] Furthermore, since the gland packing 32 lubricates while leaking a small amount of liquid, it is not desirable to place screws below the packing pressing member 40. However, according to the packing pressing member 40 of this embodiment, the packing pressing member 40 has a two-piece structure divided vertically (or diagonally) and the upper half body 41 and the lower half body 42 are fastened to each other at a left-right (or diagonal) position by the fastening portion 46. Therefore, no fastening screws are placed below the packing pressing member 40, and contamination of the fastening screws by leaked liquid is prevented.

[0027] Furthermore, according to the packing pressing member 40 of this embodiment, the fastening operation is performed at the left and right (or diagonal) positions of the two-piece structure that is divided into upper and lower parts, so that the tool is inserted and removed at the left and right or diagonal positions, making the fastening operation easy to perform visually and providing excellent maintainability.

[0028] In particular, according to the packing pressing member 40 of this embodiment, a rib 45 is provided on the base surface 43b of the base 43 at a position that does not interfere with the outer peripheral surface of the stuffing box 31, and a gap is formed between the pressing cylindrical portion 44 and the rib 45, thereby defining a cutout portion 51 that can be positioned up to a position overlapping with the rear end face 31r of the stuffing box 31 in the axial direction.

[0029] As a result, compared to the conventional two-part structure, the axial dimension can be made more compact thanks to the presence of the hollowed-out portion 51. This allows a larger working space (maintenance space) to be secured, and tools can easily enter the working space when tightening the bolts and nuts 54, further improving the ease of disassembly and assembly of the liquid-contacting parts [Invention 1, Inventions 8 and 9].

[0030] Here, in the packing pressing member 40 of this embodiment, if the upper section 41 and the lower section 42 have the same shape, then it is sufficient to use two of the same sections as the components of the packing pressing member 40, and it is only necessary to stock parts with one specification, which is advantageous in terms of reducing costs [Invention 4].

[0031] Furthermore, in the packing pressing member 40 of this embodiment, if the upper section 41 and the lower section 42 are made of the same resin, corrosion resistance is improved, which is particularly suitable for manufacturing using a 3D printer [Invention 5].

[0032] In addition, in the packing pressing member 40 of this embodiment, if there are no ribs 45 on the upper and lower sides of the base surface 43b, it is preferable for improving the ease of disassembly and assembly of the liquid-contacting part. It is also preferable as a drain path for the fluid leaking from the lower opening 53 [Invention 6].

[0033] That is, in the packing pressing member 40 of this embodiment, the periphery of the base 43 is reinforced by inserting ribs 45 at intervals in the radial direction of the pressing cylindrical portion 44, but if the openings 52, 53 are provided without ribs 45 only on the top and bottom of the base surface 43b, the upper opening 52 functions as a "check window", and the adjustment of the crushing allowance of the gland packing 32 and the checking of the degree of pressing can be made easier by visually checking the pressing cylindrical portion 44. And the lower opening 53 functions as a "drain window (hole)" for leaking liquid.

[0034] As described above, according to the packing pressing member 40 of the present embodiment, it is possible to provide a packing pressing member 40 that can uniformly press the gland packing 32 and facilitates replacement of the gland packing 32, and thus has excellent maintainability, a centrifugal pump shaft seal device 30, and a centrifugal pump 1 equipped with the same. The packing pressing member, the shaft seal device for a centrifugal pump, and the centrifugal pump equipped therewith according to the present invention are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit and scope of the present invention.

[0035] For example, in the above-described first embodiment, an example was shown in which the mating surface 48 was set along a plane horizontal to the central axis, but this is not limited to this. In a second embodiment, as shown in FIG. 3, the mating surface 48 may be configured from a combination of multiple surfaces, and in a third embodiment, as shown in FIG. 4, the mating surface 48 may be set along a plane oblique to the central axis.

[0036] Furthermore, for example, in the above embodiment, an example was shown in which the fastening portion 46 is provided by protruding to the left and right sides, but this is not limited to this. For example, as long as the upper section 41 and the lower section 42 can be fastened together, the fastening portion 46 can be formed in another suitable position that does not have a protruding structure.

[0037] However, by forming the fastening portion 46 in a protruding structure as in the above embodiment, it becomes easier to handle tools, visibility improves, and workability improves. Furthermore, if the fastening portion 46 is not formed as a protruding structure, for example, if the ribs 45 of the upper division body 41 and the lower division body 42 are moved outward, the packing pressing member 40 itself will become larger. Therefore, by forming the fastening portion 46 as a protruding structure, the packing pressing member 40 itself can be made smaller, and this, together with the two-part structure of the upper division body 41 and the lower division body 42, contributes to improving workability when assembling the packing pressing member 40 to the centrifugal pump 1.

[0038] Furthermore, if the fastening portion 46 does not have a protruding structure, when the drive shaft 2 has a large diameter, the fastening portion 46 needs to be held at a position that sandwiches the two-piece structure at a distance equal to or greater than the diameter of the drive shaft 2, making it difficult to hold the packing pressing member 40 during the fastening operation. On the other hand, if the fastening portion 46 has a protruding structure, the fastening portion 46 can be held at a protruding position regardless of the diameter of the drive shaft 2, making it easier to hold the upper section 41 and the lower section 42 of the two-piece structure.

[0039] In addition, for cooling and lubrication, the gland packing 32 is operated while allowing water to leak from the inside of the stuffing box 31 toward the atmosphere, and the leakage point for this purpose is the pressing cylindrical portion 44, which is the mating surface between the through hole 50 and the stuffing box 31. Therefore, if the fastening portion 46 does not have an overhanging structure, the position of the fastening bolt of the fastening portion 46 will be close to the water leakage part. Therefore, there is a risk of corrosion if the leaked liquid gets on the fastening bolt of the fastening portion 46. In contrast, by making the fastening portion 46 have an overhanging structure, it is possible to ensure an appropriate distance from the water leakage part and reduce the risk of corrosion.

[0040] In addition, in each of the first to third embodiments described above, an example has been shown in which the packing pressing member 40 is formed by combining the upper section 41 and the lower section 42 only radially. However, this is not limited to this, and the packing pressing member 40 can be formed by combining the two sections 41, 42 with each other in the radial or axial direction.

[0041] As a specific example, a fourth embodiment of the packing pressing member is shown in Figures 5 and 6. The fourth embodiment is an example in which one packing pressing member 40 is configured by combining two divided bodies 41, 42 with each other from the radial direction or the axial direction.

[0042] As shown in Fig. 5, in the fourth embodiment, a part of the pressing cylindrical portion 44 in one divided body 41 is formed from a convex arc portion 44a having a generally U-shape that opens downward. On the other hand, as shown in Fig. 6, in the fourth embodiment, the remaining component part of the pressing cylindrical portion 44 in the other divided body 42 is formed from a convex arc portion 44b having a generally arc shape that opens upward.

[0043] 5 and 6, one divided body 41 has a step 43c formed as a surface facing axially rearward at a position axially setback from the base 43 so that the portions corresponding to the base 43 can also be fitted together in the axial direction when fitted together radially (see FIG. 5(b)). In contrast, the other divided body 42 has a step 43d formed as a surface facing axially forward at a position axially setback from the base 43 (see FIG. 6(b)). This allows the step 43c and the step 43d to form mating surfaces, and they can be combined radially or axially to form one packing pressing member 40.

[0044] In the packing pressing member 40 of the fourth embodiment, one divided body 41 and the other divided body 42 can be combined from the radial direction or the axial direction to form a cylindrical pressing cylinder portion 44. Therefore, since the packing pressing member 40 of the fourth embodiment has a two-part structure combined from the radial direction or the axial direction, the packing pressing member 40 can be removed without disassembling the drive shaft 2 when replacing the gland packing 32. In addition, the gland packing 32 can be pressed from the axial rear over the entire circumference [Invention 2].

[0045] 7 to 9 show a fifth embodiment of the packing pressing member as an example in which the packing pressing member 40 is configured by combining two divided bodies 41, 42 with each other in the radial direction. The fifth embodiment is an example in which the two divided bodies 41, 42 are combined with each other in the radial direction to configure one packing pressing member 40. The fifth embodiment is also an example in which the two divided bodies 41, 42 have the same shape.

[0046] Specifically, as shown in FIG. 7, the divided body 41 (42) of the fifth embodiment has a convex arc portion 44c that forms half of the pressing cylindrical portion 44 and opens in a substantially U-shape. The base portion 43 of the convex arc portion 44c protrudes in the circumferential direction, and bolt insertion holes 47 are formed axially on the left and right sides. Ribs 45a, 45b, and 45c are formed around the base portion 43 at intervals in the circumferential direction. That is, a plurality of openings (outer peripheral openings 55) without ribs 45a, 45b, and 45c are formed at intervals in the circumferential direction around the base portion 43. This is suitable for further improving the disassembly and assembly of the liquid contact portion. It is also suitable as a drain path for fluid leaking from the outer peripheral openings 55 [Invention 7]. Here, in the divided bodies 41 (42) of the fifth embodiment, a front contact portion 43e, a rear contact portion 43f and a restricting portion 43m are formed in the front-rear and circumferential directions of the base portion 43 so that the divided bodies 41 (42) can be combined with each other from the radial direction. In addition, the divided body 41 (42) of the fifth embodiment is formed with a pressing portion 43g and a fitting portion 43h. The pressing portion 43g forms a portion of the packing pressing member 40 (the divided bodies 41, 42) that is pressed by the bolt 54. The engagement portion 43h is formed at the tip of the pressing portion 43g, and engages with the restricting portion 43m.

[0047] The fifth embodiment of the divided body 41 having the above-mentioned configuration uses two identical divided bodies 41, as shown in Figure 8(a), and combines one of the divided bodies 41 rotated 180 degrees in the circumferential direction with the other divided body 42 (41).

[0048] When assembling them, they are moved radially from the state shown in FIG. 1(a) so that they face each other radially on the same plane perpendicular to the axis, and then assembled by fitting the mating portion 43h into the restricting portion 43m. As a result, as shown in Fig. 1(b), a pressing cylindrical portion 44 that protrudes cylindrically in the axial direction from the base surface of the base portion 43 toward the inside of the stuffing box and presses the gland packing from the axial rear is formed as the packing pressing member 40. At the same time, a pair of bolt insertion holes 47 are formed in the base portion 43 at positions radially outward of the pressing cylindrical portion 44 that can be screwed into the rear end faces of the left and right stuffing boxes, so that a pair of bolts can be fastened thereto. Furthermore, when the restricting portion 43m and the engagement portion 43h are fitted together, the movement of one divided body 41 and the other divided body 42 in the axial direction is restricted.

[0049] In the case of the packing pressing member 40 of the fifth embodiment, as shown in Figure 9(a), one divided body 41 and the other divided body 42 of the same shape rotated 180 degrees are arranged radially opposite each other on the same plane perpendicular to the axis with respect to the shaft seal device 30. Next, as shown in Fig. 1(b), the gland packing 32 can be assembled by moving the gland packing 32 radially so that the engagement portion 43h fits into the restriction portion 43m. Next, as shown in Fig. 1(c), the assembled packing pressing member 40 can be moved axially forward and fixed with bolts and nuts 54, so that the gland packing 32 can be pressed from the axial rear over the entire circumference.

[0050] In this way, even the packing pressing member 40 of the fifth embodiment has a two-part structure assembled from the radial direction, so that when replacing the gland packing 32, the packing pressing member 40 can be removed without disassembling the drive shaft 2. Also, the gland packing 32 can be pressed all around from the axial rear [Invention 3]. [Explanation of symbols]

[0051] 1. Centrifugal pump 2 Drive shaft 3 Impeller 3a Feather 3b back feather 4 Expeller 5 Casing 5in suction side 5out discharge side 6 Front casing 7 Back casing 10 Frames 20 Seal part 30 Shaft sealing device 31 Stuffing Box 32 Gland packing 40 Packing pressing member 41 Upper division body (one of the division bodies) 42 Lower division body (other division body) 43 Base 43b Base surface 43e Front contact part 43f Rear contact part 43g Pressing part 43h Engagement part 43m Regulatory Section 44 Pressing cylinder 44m pressing surface 45 Ribs 46 Fastening Part 47 Bolt insertion hole 48 Mating surface 50 through holes 51 "Hollow-out section" 52 Upper opening "Inspection window" 53 Lower opening "Drain window (hole)" 54 Bolts and nuts 55 Outer periphery opening 60 axis branches 61,62 Bearings 70 Raina 71 Frontliner 72 Backliner 90 Bolts and nuts

Claims

1. A packing pressing member used in a shaft seal device provided at the rear of an impeller of a centrifugal pump, pressing a gland packing in a stuffing box of the shaft seal device from the axial rear, The device has a two-part structure formed by combining one divided body that is divided vertically or diagonally with the other divided body, a base portion having a base surface facing a rear end surface of the stuffing box; a pressing cylindrical portion that protrudes in an axial direction from a base surface of the base portion toward the inside of the stuffing box and presses the gland packing from the axial rear side; a pair of bolt insertion holes formed in the base along the axial direction at positions where the bolts can be screwed into rear end surfaces of the left and right stuffing boxes radially outward from the pressing cylindrical portion; a rib extending in the axial direction toward the stuffing box at a position radially outward of the pair of bolt insertion holes on the base and not interfering with an outer peripheral surface of the stuffing box; a fastening portion provided on the rib for fastening the one divided body and the other divided body to each other at a left-right or oblique position; a packing pressing member comprising said one divided body and said other divided body combined with each other.

2. A packing pressing member used in a shaft seal device provided at the rear of an impeller of a centrifugal pump, pressing a gland packing in a stuffing box of the shaft seal device from the axial rear, The device has a two-part structure formed by combining one divided part with the other divided part, a base portion having a base surface facing a rear end surface of the stuffing box; a pressing cylindrical portion that protrudes in an axial direction from a base surface of the base portion toward the inside of the stuffing box and presses the gland packing from the axial rear side; a pair of bolt insertion holes formed in the base along the axial direction at positions where the bolts can be screwed into rear end surfaces of the left and right stuffing boxes radially outward from the pressing cylindrical portion; a packing pressing member comprising said one divided body and said other divided body joined together in a radial or axial direction.

3. the one divided body and the other divided body each include a restricting portion and a mating portion which are fitted to each other, The packing pressing member according to claim 2, wherein, in a state in which the restricting portion and the engaging portion are fitted together, axial movement of the one divided body and the other divided body is restricted.

4. 3. The packing pressing member according to claim 1, wherein the one divided body and the other divided body have the same shape.

5. 3. The packing pressing member according to claim 1, wherein the one divided body and the other divided body are made of the same resin.

6. 2. The packing pressing member according to claim 1, wherein the base portion has upper and lower openings without the ribs.

7. A rib is provided on the base at a position radially outward of the pair of bolt insertion holes and not interfering with an outer peripheral surface of the stuffing box, the rib extending in the axial direction toward the stuffing box, 3. The packing pressing member according to claim 2, wherein a plurality of openings, each having no rib, are formed around the periphery of the base portion and spaced apart in the circumferential direction.

8. A shaft seal device used in a centrifugal pump for lubrication while slightly leaking pumped liquid, a stuffing box provided at a rear portion of an impeller of the centrifugal pump; and a packing pressing member attached to a rear end surface of the stuffing box and pressing a gland packing housed in the stuffing box from a rear side in the axial direction, A shaft seal device for a centrifugal pump, comprising the packing pressing member according to any one of claims 1 to 3 as the packing pressing member.

9. A centrifugal pump comprising the shaft seal device for a centrifugal pump according to claim 8.

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