JP2010255568A - Fluid machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively seal shaft penetrating parts by a small and inexpensive structure in a fluid machine including a casing with a divided structure. <P>SOLUTION: Storage grooves 41A, 41B surrounding an inner space 20 in the casing 11 and extending to the shaft penetrating parts 31A, 31B are provided in a fitting face 12a of a lower casing 12, and string-like gaskets 42A, 42B having rectangular cross sections are stored therein. The string-like gaskets 42A, 42B are clamped by the fitting faces of the lower and upper casings, and fastened and closely adhered to an outer periphery of a gland packing 32, positively sealing the shaft penetration parts 31A, 31B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fluid machine such as a pump including a turbo pump such as a centrifugal pump, a mixed flow pump, an axial flow pump, or a water turbine.

  Some casings of fluid machinery have a split structure in which casing halves are fastened with casing bolts and joined at mating surfaces. A gasket may be attached to the mating surface to prevent leakage of liquid from the inside of the casing. As this type of gasket, ring-shaped, string-shaped, and sheet-shaped gaskets are known (for example, see Non-Patent Document 1). Liquid gaskets are also known.

  Conventional ring-shaped or string-shaped gaskets generally have a circular cross-sectional shape. 6A and 6B show an example of a string-like gasket having a circular cross section. A casing 1 of a fluid machine includes a lower casing 2 and an upper casing 3. The mating surfaces 2a and 3a of the lower and upper casings 2 and 3 are joined by tightening a casing bolt (not shown). A rubber string-like gasket 5 having a circular cross section is disposed in the accommodation groove 4 formed in the mating surface 2a of the lower casing 2. 6A, the cross-sectional shape of the string-like gasket 5 is a circular shape that is close to a perfect circle before the lower and upper casings 2 and 3 are assembled. After the casings 2 and 3 are assembled, the casings 2 and 3 are sandwiched between the mating surfaces 2a and 3a to become an elliptical shape. The housing groove 4 extends to a portion (shaft penetrating portion 7) through which the main shaft 6 of the casing 1 passes, and in this portion, the right side wall is opened to the shaft penetrating portion 7 in FIGS. 4 (A) and (B). . A gland packing 8, which is a shaft seal device for the main shaft 6, is attached to the shaft penetrating portion 7. However, since the cross-section of the string-like gasket 5 is elliptical as described above, a gap is generated between the string-like gasket 5 and the gland packing 8 at the locations indicated by reference numerals A1 and A2, and the casing passes through these gaps. The liquid in 1 leaks outside. As described above, the conventional string-like gasket 5 having a circular cross section cannot reliably seal the shaft penetration portion 7 of the casing 1.

  In the case of a sheet-like gasket, in order to increase the surface pressure of the mating surface to ensure a sealing function even when the liquid inside the casing becomes high pressure, use a large casing bolt to tighten the casing half with a strong clamping force. It is necessary to tighten each other. Therefore, it is necessary to provide the casing half with a flange having a large area corresponding to a large casing bolt and a large thickness capable of withstanding a strong tightening force. As a result, the casing is increased in size and weight. Moreover, there is a case where such a large-area flange having a large thickness cannot be provided due to the structure of the fluid machine.

  In the case of a liquid gasket, the sealing function is lowered when the pressure of the liquid inside the casing becomes high.

Shigeru Sugawara, “New version pump and its usage”, Maruzen Co., Ltd., August 30, 1989, P.94-95

  An object of the present invention is to provide a fluid machine having a casing having a split structure, and to reliably seal the shaft through portion of the casing with a small, lightweight, and low-cost structure.

  The present invention includes a pair of casing halves clamped together so as to be joined at a mating surface, a space in which an impeller is disposed is formed, and a shaft penetrating portion through which a main shaft to which the impeller is fixed penetrates A casing provided with a shaft sealing device attached to the shaft penetrating portion and at least one mating surface of the casing half so as to surround the space in the casing and extend to the shaft penetrating portion. Provided is a fluid machine comprising a housing groove and a string-like gasket having a rectangular cross section housed in the housing groove.

  Since the string-shaped gasket has a rectangular cross section, when it is sandwiched between the mating surfaces of a pair of casing halves, the string-shaped gasket is in close contact with the shaft sealing device attached to the shaft penetrating part, and there is a gap between the string-shaped gasket and the shaft sealing device. Does not occur. That is, the shaft penetration part of a casing can be reliably sealed by making a string-like gasket into a rectangular section.

  Since a string-like gasket is used, a necessary sealing function can be secured even if the surface pressure of the mating surface is set lower than when a sheet-like gasket is used. Therefore, it is not necessary to use a large casing bolt for tightening, and it is not necessary to set a large area and thickness of the flange provided in the casing half. As a result, the casing bolt and the casing can be reduced in size and weight.

  Compared with liquid gaskets, the sealing function does not deteriorate even at high pressure.

  In addition to being able to reduce the size and weight of the casing bolt and casing, the string-like gasket itself is also relatively inexpensive, so that the manufacturing cost can be reduced.

  In the fluid machine of the present invention, the shaft penetrating portion of the casing can be reliably sealed with a small, light and low cost structure.

It is a perspective view showing a horizontal-axis double suction centrifugal pump according to an embodiment of the present invention. The top view of the horizontal-axis double suction vortex pump of an embodiment in the state which removed the upper casing. The top view of a lower casing. (A) And (B) is a typical fragmentary sectional view which shows the lower and upper casing and string-like gasket before and after the assembly of the casing in the horizontal-axis double suction centrifugal pump of the embodiment. The top view of the horizontal-axis double suction vortex pump of the modification in the state which removed the upper casing. (A) And (B) is typical fragmentary sectional drawing which shows the lower and upper casings and string-like gasket before and behind the assembly of the casing in a prior art example.

  1 to 4 show a horizontal-axis double suction centrifugal pump 10 (hereinafter simply referred to as pump 10) according to an embodiment of the present invention.

  The pump 10 includes a casing 11 having a split structure (horizontal split type). Specifically, the casing 11 includes a lower casing 12 and an upper casing 13. The lower casing 12 and the upper casing 13 are fastened so as to be joined at the mating surfaces 12a and 13a by a casing bolt (not shown). The casing bolt is inserted into the through holes 14 provided in the flanges 12 b and 13 b of the lower and upper casings 12 and 13.

  The internal space 20 of the casing 11 is partitioned into a suction chamber 21 and a discharge chamber 22 that are both spiral chambers. The suction chamber 21 communicates with a suction port 23 provided in the lower casing 12, and the discharge chamber 22 communicates with a discharge port 24 provided in the lower casing 12. The discharge chamber 22 accommodates a mixed flow type impeller 25. The inlets 25 a and 25 a of the impeller 25 face the suction chamber 21, and the outlet 25 b opens to the discharge chamber 22. Both ends of the main shaft 26 to which the impeller 25 is fixed extend through the casing 11 and are rotatably supported by bearings 27A and 27B. When the impeller 25 rotates together with the main shaft 26 that is rotationally driven by a drive device (not shown), the liquid sucked from the suction port 23 flows into the inlets 25a and 25a of the impeller 25 through the suction chamber 21. The liquid flowing out from the outlet 25 b of the impeller 25 is discharged from the discharge port 24 through the discharge chamber 22.

  A gland packing 32 as a shaft seal device is attached to a portion (shaft penetrating portion 31A, 31B) through which the main shaft 26 of the casing 11 passes. The gland packing 32 includes a packing 33 that is a braided structure and a packing presser 34. By tightening the packing 33 with the packing retainer 34, the packing 33 is brought into close contact with the outer periphery of the main shaft 26 to perform a sealing function, thereby preventing leakage of liquid from the internal space 20 (suction chamber 21) to the outside of the casing 11. .

  On the mating surface 12a of the lower casing 12, housing grooves 41A and 41B are formed. The individual receiving grooves 41 </ b> A and 41 </ b> B are arranged so as to generally surround the internal space 20 of the casing 11. In addition, one end 41a of each of the housing grooves 41A and 41B extends to one shaft penetrating portion 31A, and the other end 41b extends to the other shaft penetrating portion 31B. In the end portions 41a and 41b, one side wall of the housing grooves 41A and 41B is open to the shaft through portions 31A and 31B (the end portions 41a and 41b and the shaft through portions 31A and 31B communicate with each other). For example, as shown in FIGS. 4A and 4B, at the end 41b of the housing groove 41A, the right side wall in the drawing of the housing groove 41A is open to the shaft penetrating portion 31B. Further, both end portions 41a and 41b of the housing grooves 41A and 42B extend to the outer peripheral surface of the lower casing 12 beyond the shaft penetration portions 31A and 31B.

  String-like gaskets 42A and 42B are accommodated in the individual accommodating grooves 41A and 41B, respectively. The cross-sectional shape of the string-like gaskets 42A and 42B is rectangular. In this specification, the “rectangular shape” includes a square, a rectangle, or a shape that can be regarded as substantially these shapes. For example, a shape in which a corner is rounded or chamfered is also included in the rectangular shape. The string-like gaskets 42A and 42B are disposed without interruption from one end 41a of the housing grooves 41A and 41B to the other end 41b. As shown in FIG. 4 (A), the shape and dimensions of the string-like cross section are set so as to protrude by a predetermined amount from the mating surface 12a of the lower casing 12 before the lower and upper casings 12 and 13 are assembled (tightening). Teenage). The material constituting the string-like gaskets 42A and 42B is preferably a material having elasticity, flexibility, denseness that does not allow liquid to permeate, and toughness that resists clamping force. Examples of the material having such characteristics include rubbers such as natural rubber and synthetic rubber.

  As shown in FIG. 4B, when the lower and upper casings 12 and 13 are assembled, the string-like gaskets 42A and 42B are sandwiched between the mating surfaces 12a and 13a by tightening the casing bolts (not shown). The cross-sectional shapes of the gaskets 42A and 42B are deformed. As a result, the mating surfaces 12a and 13a are in close contact with the upper and lower surfaces in the figure of the string-like gaskets 42A and 42B, and pass through the mating surfaces 12a and 13a from the internal space 20 (the suction chamber 21 and the discharge chamber 22) to the outside of the casing 11. Prevent liquid leakage. That is, the string-like gaskets 42A and 42B perform the sealing function of the mating surfaces 12a and 13a.

  As shown in FIG. 4B, when the lower and upper casings 12 and 13 are assembled and sandwiched between the mating surfaces 12a and 13a, one side of the cross-section of the string-like gaskets 42A and 42B (FIG. 4B ) Is in close contact with the outer peripheral surface of the gland packing 32 (specifically, the packing 33) without a gap. Referring also to FIG. 6 (B), in the case of the string-like gasket 5 having a circular cross section, a gap is generated between the string-like gasket 5 deformed into an elliptical shape and the gland packing 8 at locations indicated by reference signs A1 and A2. The liquid in the casing 1 leaks outside through these gaps. However, as shown in FIG. 4B, in the case of the string-like gaskets 42A and 42B of the present embodiment having a rectangular cross section, one of the cross-sectional shapes of the string-like gaskets 42A and 42B including the portions indicated by reference numerals A1 and A2 The entire side portion of the gland closely adheres to the outer peripheral surface of the gland packing 32 without a gap. Accordingly, by making the cross-sectional shape of the string-like gaskets 42A and 42B rectangular as in the present embodiment, the shaft penetration portions 31A and 31B of the casing 11 are reliably sealed, and liquid leakage from this portion is prevented. it can.

  Further, in the present embodiment, since the string-like gaskets 42A and 42B are used, a necessary sealing function can be ensured even if the surface pressure of the mating surfaces 12a and 13a is set lower than when the seal-like gasket is used. . Therefore, it is not necessary to use a large-sized casing bolt for tightening, and it is not necessary to set the area and thickness of the flanges 12b and 13b provided in the lower and upper casings 12 and 13 to be large. As a result, the casing bolt and the casing 11 can be reduced in size and weight.

  Furthermore, as compared with a liquid gasket, the sealing function does not deteriorate even when the pressure of the liquid in the internal space 20 of the casing 11 becomes high.

  Furthermore, in addition to being able to reduce the size and weight of the casing bolt and the casing 11, the string-like gaskets 42A and 42B themselves are also inexpensive, so that the manufacturing cost can be reduced.

  The present invention is not limited to the embodiments, and various modifications are possible. For example, a mechanical seal 52 may be employed instead of the gland packing 32 as a shaft seal device for the main shaft 6 as shown in FIG. In addition to the lower casing 12, the housing groove 41 may be provided in the upper casing 13, or the housing groove 41 may be provided only in the upper casing 13. Furthermore, the present invention is not limited to the horizontal-axis double suction centrifugal pump as in the embodiment, but can be applied to various types of turbo pumps and can also be applied to water turbines.

DESCRIPTION OF SYMBOLS 1 Casing 2 Lower casing 2a Matching surface 3 Upper casing 3a Matching surface 4 Accommodating groove 5 String-like gasket 6 Main shaft 7 Shaft penetration 8 Ground packing 10 Horizontal shaft double suction centrifugal pump 11 Casing 12 Lower casing 12a Matching surface 12b Flange 13 Upper casing 13a Mating surface 13b Flange 14 Through hole 20 Internal space 21 Suction chamber 22 Discharge chamber 23 Suction port 24 Discharge port 25 Impeller 25a Inlet 25b Outlet 26 Main shaft 27A, 27B Bearing 31A, 31B Shaft through portion 32 Gland packing 33 Packing 34 Packing retainer 41A, 41B receiving groove 41a, 41b end 42A, 42B string-like gasket 52 mechanical seal

Claims (1)

A pair of casing halves that are fastened together so as to be joined at the mating surfaces are provided, a space in which the impeller is arranged is formed, and a shaft penetrating portion through which the main shaft to which the impeller is fixed is provided. A casing,
A shaft sealing device attached to the shaft penetrating portion;
A housing groove formed on at least one mating surface of the casing half so as to surround a space in the casing and extend to the shaft penetrating portion;
A fluid machine comprising: a string-like gasket having a rectangular cross section housed in the housing groove.

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