JPH11324964A - Casing structure for centrifugal multi-stage pump and suction casing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reconcile an increase in the strength and a decrease in the weight of a device and to reduce the cost while eliminating the cutting work of a casing so as to reduce the number of parts items of the casing. SOLUTION: In this pump, plural impellers 3 are housed in a casing in a direction of a driving shaft 2. The casing is formed of a suction casing 4, a discharge casing 5 and a seal cover 15, and the suction casing 4 is formed of steel plates and formed into a plate shape, and has a suction port 4a, and a suction flange 4c and plural holder pieces 4d are welded to the suction casing 4. The discharge casing 5 is formed of steel plates and formed into a cylindrical shape, and has a discharge port 5 in the peripheral wall, and a discharge base 5d with a discharge flange 5c is welded to the discharge casing 5. Further, the seal cover 15 is formed of steel plate and formed into a plate shape and has a hole 15b for passing the driving shaft 2. These suction casing 4, the discharge casing 5, and the seal cover 15 are integrally fastened with each other by a through bolt 10 inserted into a hole of the holder pieces 4d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a casing structure and a suction casing for a centrifugal multistage pump.

[0002]

2. Description of the Related Art Some centrifugal centrifugal pumps have a cross-sectional structure in a side view as shown in FIG.

[0003] To explain the outline, 1 is an electric motor, 2
Is a drive shaft rotated by the electric motor 1. A plurality of impellers 3 are fixed to the drive shaft 2 in series. Reference numeral 4 denotes a suction casing having a suction port 4a, and reference numeral 5 denotes a discharge port 5a on an outer peripheral portion.
And is fixed to the frame 1 a of the electric motor 1.

[0004] An outer cylinder 6 is arranged between the suction casing 4 and the discharge casing 5, and a cylindrical spacer 7 and guide vanes 8 are arranged in the outer cylinder 6 in a stepped manner. Are integrally fastened by through bolts 10 inserted into holes of the suction cover 9. Thus, a passage 11 is formed inside the cylindrical spacer 7 and the guide blade 8 for sequentially guiding the liquid sucked from the suction port 4a to each impeller 3.

[0005] O-rings 12 are attached to both ends of the outer cylinder 6, and the O-rings 12 connect the ends of the outer cylinder 6 with the suction casing 4 and the discharge casing 5 in a watertight manner. .

Reference numeral 13 denotes a discharge liquid chamber which covers the outside of the guide blade 7 at the leftmost position. A shaft sealing device is provided in the center of the chamber 13 to seal a penetrating portion of the drive shaft 2. (Mechanical seal) 14 is provided. This shaft sealing device 14 is a seal cover 1 attached to the center of the discharge casing 5.
5 is supported.

[0007]

In the conventional pump described above, the suction casing 4 and the discharge casing 5 are generally made of resin, which contributes to weight reduction and reduction of production cost, but is inferior in strength. Therefore, a metal seal cover 15 is required in the vicinity of the shaft sealing device 14, and it is necessary to provide a metal suction cover 9 in addition to the suction casing, and to insert the bolt 10 through the metal suction cover 9.

When the discharge liquid pressure becomes high, the suction casing 4 and the discharge casing 5 are made of casting, but in this case, these casings 4 and 5 need to be cut and the weight increases. There is a disadvantage to doing.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a casing structure of a centrifugal multi-stage pump, which makes it possible to increase the strength and reduce the weight while eliminating the need for cutting the suction casing and the discharge casing. It is an object to provide a suction casing.

[0010]

According to the present invention, there is provided a centrifugal multi-stage pump in which a plurality of impellers are accommodated in a casing in the direction of a drive shaft thereof. Formed by a discharge casing and a seal cover, the suction casing is formed in a generally dish shape by a steel plate, has a suction port, and is formed by welding a suction flange and a plurality of holders, and the discharge casing is formed into a substantially cylindrical shape by a steel plate. It is formed, has a discharge port on the peripheral wall, and is welded to a discharge port with a discharge flange, and the seal cover is formed in a dish shape by a steel plate and has a hole through which the drive shaft is penetrated. The suction casing, the discharge casing, and the seal cover are integrally fastened by a through bolt inserted into a hole of the holder.

At this time, a small step is formed by providing a slight step at both ends of the discharge casing, and an annular groove into which an O-ring is fitted is formed at the root of each small diameter portion.

According to the present invention, since the casing is made of a steel plate, the strength is increased as compared with the resin, and the weight is reduced as compared with the casting. Further, the processing accuracy of the casing is improved, and the cutting processing is not required.

The casing is formed of three parts,
The number of parts is smaller than before. Further, the provision of the small-diameter portions at both ends of the discharge casing makes it possible to perform high-quality machining of the peripheral edges of the suction casing and the seal ring.

[0014]

FIG. 1 is a sectional side view showing a centrifugal multistage pump according to one embodiment of the present invention, FIG. 2 is a front view of the pump, and FIG. 3 shows a suction casing used for the pump. FIG. 4 is a sectional view showing a peripheral portion of a suction casing used in the pump, and FIG. 5 is a view showing a final stage guide blade used in the pump. In these figures,
Substantially the same parts as those of the prior art are denoted by the same reference numerals.

In the pump according to the present embodiment, the casing forming the outer shell is formed by a suction casing 4, a discharge casing 5 and a seal cover 15, as shown in FIG.

Here, the entire suction casing 4 is formed in a generally dish shape from a steel plate. More specifically, FIG.
The steel plate is bent into a dish shape as shown in Fig.
b, a main body k1 having a suction port 4a is formed at the center, and a steel plate suction flange 4c is welded to the suction port 4a, and a steel plate is formed at four places around the main body k1. In addition to welding the holder piece 4d in an overhang shape, the mounting plate 4e for connecting the leg 16 is welded.

The discharge casing 5 is formed entirely of a steel plate into a substantially cylindrical shape, and more specifically, forms a cylindrical main body k2 having a discharge port 5a on the peripheral wall. 4 are provided at both ends to form small-diameter portions 5b, annular grooves m are formed at the roots of the small-diameter portions 5b, and a discharge flange 5c made of steel plate is provided at the discharge port 5a. The outlet metal 5d is welded.

The seal cover 15 is formed in a dish shape by a steel plate as a whole. More specifically, the steel plate is bent to form a short cylindrical portion 15a at a peripheral edge, and a hole through which the drive shaft 2 penetrates is formed at a central portion. 15b.

The through bolt 10 is screwed into the frame 1a of the electric motor 1 while being inserted into the hole of each holder piece 4d of the suction casing 4, and the suction casing 4, the discharge casing 5 and the seal cover 15 are connected to these through bolts. 10 is fastened integrally with the electric motor 1.

At this time, the cylindrical portion 4b of the suction casing 4 is fitted to the small diameter portion 5b at one end of the discharge casing 5,
The small-diameter portion 5b at the other end has a cylindrical portion 15a of the seal cover 15.
To the outside. Reference numeral 12 denotes an O-ring which is formed in an outer ring in the annular groove m of the small-diameter portion 5b, and has a relatively large diameter to maintain a strong watertight state between the small-diameter portion 5b and the cylindrical portions 15a and 4b. .

The discharge liquid chamber 13 has such an axial length that the mechanical seal 14 can be accommodated between the seal cover 15 and the last stage guide blade 8.

Here, the guide vanes 8 at the last stage are as follows. That is, as shown in FIG.
A circular recess 8a for surrounding the impeller 3 is formed on the front surface opposite to the above, and a plurality of arc-shaped convex blades 8b are provided on an outer peripheral edge outside the recess. A guide path w is formed.

On the other hand, on the back surface facing the seal cover 15, three leg portions 8c and resistance blades 8d inclined in a required direction related to the liquid flow in the discharge liquid chamber 13 project backward. It is provided in.

At this time, the leg portion 8c is provided in a plate shape so as to extend along a plurality of circumferential portions of the peripheral edge portion of the guide blade 8,
The resistance blade 8d is formed integrally with one specific leg 8c.

In the figure, 17 is the shaft sleeve, 18 is the impeller 3
, And 19 is a drain port.

In this embodiment configured as described above,
When the through-bolt 10 is tightened, the suction casing 4 becomes the discharge casing 5 as well as the cylindrical spacer 7 and the guide vanes 8.
Is pressed toward the front surface of the seal cover 15.

As a result, the legs 8 of the last stage guide vanes 8
c is strongly pressed against the seal cover 15, and the guide blade 8, the cylindrical spacer 7, and the suction casing 4 are strongly pressed against each other by the reaction force caused by the pressure, and are integrally fixed to the frame 1 a of the electric motor 1. You. At this time, the leg 8c
That the guide vanes 8 are formed along the circumferential direction of the guide vanes 8, the guide vanes 8, the cylindrical spacers 7 and the suction casing 4 are fixed stably and firmly.

When the electric motor 1 is rotated, liquid is sucked from the suction port 4a, and the liquid is passed through the passage 11 formed by the cylindrical spacer 7 and the guide blade 8, and the first and second stage impellers 3. , And reaches the impeller 3 at the last stage.

The liquid exiting the last stage impeller 3 flows in the outward guide path w of the last stage guide blade 8 in the centrifugal direction and reaches the discharge liquid chamber 13. Most of the liquid that has reached here flows in the discharge liquid chamber 13 on the centrifugal direction side of the leg 8c in the circumferential direction thereof and is sent out from the discharge port 5a.

By the way, the liquid on the center side of the leg portion 8c in the discharge liquid chamber 13 is vibrated by the liquid or the like, and the impeller is caused by the flow of the liquid flowing out of the outward guide path w of the guide blade 8 at the last stage. 3 is rotated in the rotation direction. When such a rotational flow of the liquid occurs, the liquid flow collides with the resistance blade 8d and is suppressed.

Further, the liquid that has collided with the resistance blade 8d flows toward the center of the discharge liquid chamber 13 due to the inclination of the resistance blade 8d, and flows through the periphery of the mechanical seal 14 in the discharge liquid chamber 13 in the centrifugal direction. This flow generates a liquid flow that constantly supplies new liquid to the mechanical seal 14 during the rotation of the electric motor 1, and lubricates the sliding surface 14a.

[0032]

According to the present invention configured as described above,
The following effects are obtained. According to the first aspect, since the suction casing and the discharge casing are formed of a steel plate, it is possible to achieve both an increase in strength and a reduction in weight.

In addition, these casings do not require cutting because the machining accuracy is improved as compared with the case where they are made into a cast article. Further, the discharge casing also serves as a conventional outer cylinder, and the suction casing replaces the conventional suction cover. Since they are also used, the number of parts of the casing is reduced, which contributes to a reduction in production cost.

Further, since the bending radius of the bent portion at the root of the cylindrical portion of the suction casing and the seal cover can be made larger than that in the case where the small diameter portion does not exist, excessive stress acts on this bent portion. The generated cracks will not occur.

According to the third aspect, the same effect as the first aspect is obtained for the suction casing.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a centrifugal multistage pump according to one embodiment of the present invention.

FIG. 2 is a front view of the pump.

FIG. 3 is a view showing a suction casing used for the pump.

FIG. 4 is a sectional view showing a peripheral portion of a suction casing used for the pump.

5A and 5B show a guide vane at the last stage used in the pump, wherein A is a view from the front side and B is a view from the rear side.

FIG. 6 is a side sectional view showing a conventional centrifugal multistage pump.

[Explanation of symbols]

 2 Drive shaft 4 Suction casing 4a Suction port 4c Suction flange 4d Holder piece 5 Discharge casing 5a Discharge port 5b Small diameter portion 5c Discharge flange 5d Discharge mouthpiece 10 Through bolt 12 O ring 15 Seal cover 15b Hole m Annular groove Δr Step

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[Procedure amendment]

[Submission date] May 15, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4 ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 10, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

According to the present invention, there is provided a centrifugal multi-stage pump in which a plurality of impellers are accommodated in a casing in the direction of a drive shaft thereof. The suction casing is formed from a discharge casing and a seal cover, and the suction casing is formed in a generally dish shape by a steel plate.The suction casing has a suction port, a suction flange and a plurality of holders are welded, and the suction casing is externally fitted to one end. An annular groove in which a small step is formed by providing a slight step at both ends of the discharge casing in which a seal cover is externally fitted at the other end, and an O-ring is fitted at the base side of each small diameter part. On the other hand, the seal cover is formed in a dish shape by a steel plate and has a hole through which the drive shaft passes. Over by through bolts inserted through the hole of the holder, it forms a structure in which small diameter portion edge and the suction casing and the inner surface of the seal cover of the discharge casing ends are fastened together form contacts.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

At this time, an O-ring having a relatively large diameter is fitted into the annular groove, and the O-ring is used to press and contact the suction casing fitted on the discharge casing and the back side of the seal cover. And

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The discharge casing 5 is formed entirely of a steel plate into a substantially cylindrical shape, and more specifically, forms a cylindrical main body k2 having a discharge port 5a on the peripheral wall. 4 are formed at both ends to form small-diameter portions 5b, and annular concave grooves m for fitting O-rings are formed at the bases of the small-diameter portions 5b. The discharge port 5a is made of steel. The formed discharge flange 5d with the discharge flange 5c is welded.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

At this time, the cylindrical portion 4b of the suction casing 4 is fitted to the small diameter portion 5b at one end of the discharge casing 5,
The small-diameter portion 5b at the other end has a cylindrical portion 15a of the seal cover 15.
To the outside. Reference numeral 12 denotes an O-ring fitted into an annular groove m formed on the base side of the small-diameter portion 5b, and a suction casing 4 and a seal cover 15 fitted on the discharge casing 5 using a relatively large diameter. The back side of the camera is held in a strong watertight state.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

[0032]

According to the present invention configured as described above,
The following effects are obtained. According to the first aspect, since the suction casing and the discharge casing are formed of a steel plate, it is possible to achieve both an increase in strength and a reduction in weight. Particularly, a small step is formed at both ends of the discharge casing to form a small-diameter portion, and an annular concave groove is formed at the base side of the small-diameter portion to form a suction casing at one end and a seal cover at the other end. The O-ring having a relatively large diameter is fitted into the annular groove, and the back side of the suction casing and the seal cover which are fitted on the discharge casing by the O-ring. A pressure-contacting means, and a small-diameter portion edge provided with a slight step at both ends of the discharge casing and an inner surface side of the suction casing and the seal cover are integrally tightened and fixed with a through bolt in a state of contact. What has been done contributes to stabilizing the position of the O-ring, stabilizing the quality during assembly, and improving workability.

Claims (3)

[Claims] 1. A centrifugal multi-stage pump in which a plurality of impellers are accommodated in a casing in a drive shaft direction thereof, wherein the casing is formed of a suction casing, a discharge casing and a seal cover, and the suction casing is generally made of a steel plate. The discharge casing is formed in a dish shape, has a suction port, and is welded to a suction flange and a plurality of holders.The discharge casing is formed in a substantially cylindrical shape by a steel plate, has a discharge port in a peripheral wall, and has a discharge flange. The seal cover is formed of a steel plate in a dish shape and has holes through which the drive shaft passes.The suction casing, the discharge casing, and the seal cover have holes in the holder. A casing structure of the centrifugal multi-stage pump, wherein the casing is integrally fastened by a through bolt inserted through the casing. 2. A small diameter portion is formed by providing a small step at both ends of a discharge casing having a suction casing fitted on one end and a seal cover fitted on the other end. The casing structure for a centrifugal multistage pump according to claim 1, wherein an annular groove into which the O-ring is fitted is formed. 3. A suction casing for a centrifugal multi-stage pump, wherein the suction casing is formed in a substantially dish shape by a steel plate, has a suction port, and is welded to a suction flange and a plurality of holders.