JP2003148390A - Double suction turbine pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double suction turbine pump which is maintenance-free, capable of being stably operated for a long time and preventing a radial bearing from being damaged by an uneven touch, and improving the reliability. SOLUTION: Blades 2 fixed to a pump shaft 1 are surrounded by a pump casing 3 to form a water passage, both sides of the pump shaft 1 are supported by bearings, both bearings are radial bearings comprising sliding bearings, a seal part and a thrust bearing are formed between both sides of the blades and a fixed part, sliding parts of both radial bearings 4a are formed of a thermoplastic resin, and water pumped by the pump is used for a lubricant of the bearings 4a and 4b and the seal part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double suction centrifugal pump, and more particularly to a double suction centrifugal pump which uses pumped water as a lubricant for bearings and seals.

[0002]

2. Description of the Related Art As a conventional double suction centrifugal pump,
It is equipped with a pump main shaft with fixed blades, a pump casing that surrounds the outer periphery of the blades to form a water passage, and bearings that support the pump main shaft on both sides of the part with the fixed blades. There is a radial bearing composed of a metal or grease-lubricated rolling bearing and a thrust bearing arranged in parallel with the radial bearing, and there is a bearing configured to be held at a position away from the pump casing. Related to this is, for example, the one described in JP-A-9-137795.

[0003]

However, in the above-mentioned prior art, since the bearing is a radial bearing composed of an oil-lubricated white metal or a grease-lubricated rolling bearing, the lubricating oil or grease used in the bearing is used. There is a problem that it needs to be replaced regularly, maintenance-free is difficult, and lubricating oil and grease easily leak.

Further, in the above-mentioned prior art, since the bearing is configured to be held at a position away from the pump casing, the radial support span between both bearings becomes long and it is difficult to suppress vibration during high speed rotation. It was difficult to reduce the size and speed.

An object of the present invention is to obtain a highly reliable double suction centrifugal pump which is maintenance-free and can be stably operated for a long period of time and which can prevent damage to a radial bearing. Another object of the present invention is to obtain a double-suction centrifugal pump that is maintenance-free and can reduce vibration during high-speed rotation to reduce the size and speed of the pump and improve efficiency.

[0006]

In order to achieve the above object, a double suction centrifugal pump, which is one of the typical inventions of the present invention, encloses a pump main shaft having fixed blades and an outer circumference of the blades. In a double-suction centrifugal pump having a pump casing that forms a water passage and bearings that support the pump main shaft on both sides of the portion to which the blades are fixed, the bearings provided on both sides are radial bearings that are slide bearings. In addition, a seal portion and a thrust bearing are formed between both side surfaces of the blade and the fixed portion, and pump water is used as a lubricant for all the bearings. At this time, the sliding portion of the radial bearing may be formed of a thermoplastic resin. Since it is a bi-suction swirl pump with bearings and seals, the bearings can be directly lubricated by pumping water and maintenance is unnecessary. Since pumped water is used as the lubricant, no grease or lubricating oil is needed, and contamination can be prevented. In addition, because it is arranged so that the span of the bearing can be minimized,
The support rigidity of the pump main shaft is high and it is possible to cope with high speed.
Further, it is effective for downsizing the double suction centrifugal pump. On the other hand, since it has been experimentally confirmed that the thermoplastic resin exhibits stable sliding characteristics even in a high load region under pumping lubrication, sufficient load capacity can be obtained. Therefore, in the pump having the thermoplastic resin housed in the bearing portion, stable pump performance can be maintained and high reliability can be secured for a long time. In the high load region, the thermoplastic resin softens the sliding surface of the bearing even if the water film locally breaks, easily flows, smoothes, and becomes easily fit. Since the thermoplastic resin easily flows at the local contact portion, the pump spindle side is not damaged. As described above, with the arrangement of the bearing and the seal portion according to the present invention, the bearing and the seal portion are directly lubricated by pumping water, and the pump having the thermoplastic resin accommodated in the bearing portion and the seal portion is stable for a long period of time. It is possible to provide a double suction centrifugal pump that can maintain pump performance and can be stably operated for a long period of time.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the second and subsequent embodiments, the duplicated description of the configuration common to the first embodiment is omitted. In addition, the same code | symbol in the figure of each Example shows the same thing or equivalent thing.

First, a first embodiment of the present invention will be described with reference to FIGS.
Will be explained. 1 is a longitudinal sectional view of a double-suction centrifugal pump according to a first embodiment of the present invention, FIG. 2 is a front view of a seal and a thrust bearing portion of the double-suction centrifugal pump of FIG. 1, and FIG.
2 is a sectional view taken along the line aa of the seal and the thrust bearing portion of FIG. 2, and FIG. 4 is a pressure distribution chart of the seal and the thrust bearing portion of FIG.

The double-suction centrifugal pump is used as a pump for supplying clean water, and includes a pump main shaft 1, blades 2, a pump casing 3, a radial bearing 4a, thrust bearings 4b and 4c, and seal portions 5b and 5c. The casing cover 6 and the seal 7 are provided.

Pump spindle 1 made of stainless steel
Are horizontally supported by the pump casing 3 via bearings, and one end portion of the pump is projected to the outside of the pump casing 3. A coupling portion 8 connected to the drive mechanism is attached to this one end portion. The blade 2 is the pump main shaft 1
It is configured to be fixed to the outer circumference of the central portion of the pump, rotate with the pump main shaft 1, suck water from both sides, and discharge the water in the outer circumferential direction. The pump casing 3 surrounds the outer periphery of the blade 2, and has a thrust bearing and a support portion 3b of the seal portion near the side surface of the blade 2 and radial bearing support portions 3a on both side surfaces facing the water passage. A radial bearing 4a, a thrust bearing 4b, and a seal portion 5 that support the pump main shaft 1.
b are arranged on both sides of the blade 2.

The two radial bearings 4a, which are cylindrical plain bearings, are fixed in close contact with bearing support portions 3a provided on both side surfaces of the pump casing 3, and the pump main shaft 1
The blades 2 are rotatably and slidably supported on both sides of the blade 2. The pump casing portion located on the water passage side (inner side) of the radial bearing 4a has a gap with the pump main shaft 1 so that the inner side of the radial bearing 4a communicates with the water passage in the pump casing 3. It is configured.
As a result, the pump casing 3 is attached to the radial bearing 4a.
Pumped water is supplied to the internal waterway. Further, the radial bearing 4a is provided with a plurality of grooves (not shown) penetrating in the axial direction at horizontal positions. As a result, pumped water is guided from the water passage to the plurality of grooves, and the sliding surface of the radial bearing 4a is reliably lubricated.

Here, the thermoplastic resin material 10 is processed into a ring shape, the radial bearing 4a is manufactured, press-fitted and fixed to the pump casing 3 and directly attached. However, a resin layer is formed only on the sliding surface to form a backing metal. It may be manufactured by attaching it to the etc.
When the resin layer is formed only on the sliding surface using the thermoplastic resin material, specifically, it has a three-layer structure (back metal-intermediate layer-resin), and the back metal (material: corrosion-resistant material such as SUS316) has an intermediate layer. A sintered filter (material: a corrosion-resistant material such as SUS316) is joined by nickel brazing or the like, and a thermoplastic resin material is press-fitted onto the surface of the joined sintered filter and attached by utilizing the anchor effect.

As the thermoplastic resin material, a polyether ether ketone resin (hereinafter referred to as PEEK resin) or a polyphenylene sulfide resin (hereinafter referred to as PPS resin) is used with or without carbon fibers mixed therein.

FIG. 2 shows a front view of the thrust bearing 4b and the seal portion 5b formed near the side surface 3b of the blade 2. The position of point A in the figure indicates the outer diameter of the thrust bearing 4b, and has the same dimension as the outer diameter of the blade. Point B in the figure indicates the inner diameter of the seal portion 5b. The thrust bearing 4b and the seal portion 5b are formed by processing a step on the surface facing the blade side surface. As shown in the figure, there are four stepped portions in the circumferential direction. The same steps are processed at all four locations. The range from the point C to the point A in the figure in which the step is processed is used for the thrust bearing 4b, and the range from the point C to the point B in the figure is used for the seal portion 5b.

FIG. 3 is a sectional view taken along the line aa of FIG. The thrust bearing 4b is a portion from the point C to the point A that has been machined and removed. Since the seal portion 5b is not stepped, the gap formed between the side surface of the blade and the side surface of the blade can be reduced, so that it can be used as a seal portion.

FIG. 4 shows the thrust bearing 4b and the seal portion 5b.
The pressure distributions at points A, B, and C of the portion forming the are shown. A
The pressure at the point corresponds to the pump discharge pressure, and the pressure at the point B corresponds to the pump suction pressure. The range from point C to point A is the pump discharge pressure, which is a constant value. In the range from point C to point B, the pump discharge pressure drops linearly to the pump suction pressure. In the conventional example, the pump discharge pressure linearly drops from the pump discharge pressure to the pump suction pressure in the range from point A to point B.

Since the thrust bearing 4b is constructed in the range from the point C to the point A of the step, this range is equivalent to the pump discharge pressure, and the force for pressing the blade can be increased as compared with the conventional case. As a result, the action of the hydrostatic bearing is exhibited, and it can be used as a thrust bearing. Further, the force for pressing the blades is increased in the area shown by the shaded area as compared with the conventional example, and it becomes possible to suppress the vibration in the axial direction.

In the range from the point C to the point B, which constitutes the seal portion, the pressure drops linearly from the pump discharge pressure to the pump suction pressure. Since the amount of leakage from the seal portion is proportional to the cube of the gap formed with the blade side surface, it can be set to an appropriate value by setting the gap small.

Here, the thrust bearing 4b and the seal portion 5b are made of a thermoplastic resin material, and bolts or the like (not shown).
Although it is directly fixed to the thrust bearing and the support portion 3b of the seal portion by means of, the thrust bearing and seal portion with the back metal having the resin layer formed only on the sliding surface are manufactured, and the bolt (not shown) is provided through the back metal. For example, it may be fixed to the thrust bearing and the support portion 3b of the seal portion. When a resin layer is formed using a thermoplastic resin material only on the sliding surface, it has a three-layer structure (back metal-intermediate layer-resin), as in radial bearings.
The back metal (material: corrosion-resistant material such as SUS316) is bonded to the sintered filter (material: corrosion-resistant material such as SUS316) of the intermediate layer with nickel braze, and the surface of the bonded sintered filter is covered with a thermoplastic resin material. It is press-fitted and attached using the anchor effect.

In the double suction centrifugal pump of this embodiment, since the radial bearing 4a, the thrust bearing 4b, and the seal portion 5b use pumped water of the pump as a lubricant,
The conventional lubricating oil and grease are no longer needed, maintenance-free can be realized, and the surrounding pollution due to the leakage of lubricating oil and grease can be eliminated, making it an environmentally friendly pump.

Further, since the radial bearings 4a supporting both sides of the pump main shaft 1 are held by the water passage portion of the pump casing 3 and the thrust bearings are arranged in the vicinity of the side surfaces of the blades, the conventional pump casing is not required. Both radial bearings 4a, as compared with those that support the bearings at distant positions
The span between them can be reduced, which can increase the bearing support rigidity.

As a result, the vibration of the pump during high speed rotation can be reduced, and the size and speed of the pump can be reduced and the efficiency of the pump can be improved. Further, since the sliding portions of both the radial bearings 4a and the thrust bearings 4b are formed of a thermoplastic resin material, swelling like a conventional thermosetting resin (for example, phenol resin) under water lubrication using pumped water. Almost no shape change occurs due to, a stable low friction coefficient is obtained even in a high load region, and the initial bearing sliding surface shape can be maintained for a long period of time. As a result, the reliability for long-term operation is significantly improved. Also, both radial bearings 4a
Also, the thermoplastic resin material forming the sliding portion of the thrust bearing 4b softens the sliding surface even if the water film locally breaks due to uneven contact with the pump main shaft 1 in the high load region. Flow easily occurs, smoothing progresses, and the pump main shaft 1 and the vanes 2 are stabilized in a state of conforming to their side surfaces. In this way, the thermoplastic resin material easily flows when it locally contacts, so that damage to the main shaft side and the blade side surface can be prevented. Therefore, stable pump performance can be maintained and high reliability is ensured for a long period of time.

In order to confirm the effect of using a thermoplastic resin material for the sliding portion of the bearing, a sliding element test was performed on various materials using a combination of a ring-shaped rotating side material and a ring-shaped stationary side material to determine the critical surface pressure, And, the sliding surface was inspected for damage. As the operating condition, the fixed side material has 6 radial grooves for water lubrication.
Rotate the rotating side material for about 30 minutes at the surface pressure (limit surface pressure) at which the peripheral speed is constant at a constant 5 m / s and the friction coefficient starts to rise, while the main formation is performed and water is lubricated on the sliding surface with water. .

The results of this sliding element test are shown in Table 1.

[0025]

[Table 1] As is clear from Table 1, by using PEEK-based resin and PPS-based resin in water lubrication and combining a two-layer stainless steel or cemented carbide coating, an extremely high limit surface pressure of 5 MPa or more was obtained, and after-test sliding From the observation result of the moving surface, it was confirmed that neither rotation side damage nor fixed side damage was observed. In particular,
In the combination of the cemented carbide coating and the PEEK resin, the test piece No. As is clear from No. 1, the extremely high limit surface pressure of 7 MPa (the limit surface pressure of 5MP due to the combination of the two-layer stainless steel of test piece No. 2 and PEEK resin)
A higher limit surface pressure of 40% was obtained compared to a. The double-layer stainless steel has a Vickers hardness of 600.
In the above, as the cemented carbide coating, a nickel binder type cemented carbide having corrosion resistance was used.

PEEK for forming a thermoplastic resin material
It has been found that by mixing carbon fibers with a resin or a PPS resin, the mechanical strength of the thermoplastic resin material is improved, and the carbon fiber portions serve as water pools, exhibiting a remarkably excellent lubricating effect. It was

FIG. 5 shows a second embodiment of the present invention. Figure 6
Shows a bb sectional view of FIG. 5. This embodiment is different from the above-mentioned first embodiment in the following points.

This embodiment is different from the first embodiment in that the thrust bearing 4b is a taper land bearing having a sliding surface formed with a taper portion 4b2. Groove 4
The tapered portion 4b2 is processed in the circumferential direction so as to communicate with b1. The seal portion 5b1 also serves as a land portion. The angle of the tapered portion, the number of tapered portions, the width, etc. are determined by the magnitude of the thrust load, and are not particularly limited. According to the present invention, since the taper land bearing is used, the thrust load capacity can be increased.

FIG. 7 shows a third embodiment. This embodiment is different from the above-mentioned first embodiment in the following points.

This embodiment is different from the first embodiment in that the side surface 2a of the blade 2 and the thrust bearing 4b facing the blade 2 and the sliding surface constituting the seal portion 5b are tapered surfaces 4b3 and 5b2. It is different. According to the present invention, at the initial stage of assembling the pump casing 3, since the thrust bearing 4b and the seal portion 5b facing the side surface outer periphery of the blade 2 can be set in a wide state, interference can be prevented and the assembling workability is improved.

FIG. 8 shows a fourth embodiment. This embodiment is different from the above-mentioned first embodiment in the following points.

In the present embodiment, the thrust bearings 4b4, 4b5 and the seal portion 5 provided at the opposite positions on the side surface of the blade 2 are provided.
This is different from the first embodiment in that b3 and 5b4 are asymmetrical. According to the present invention, since the load capacity of the thrust bearing 4b5 is larger than that of the thrust bearing 4b4, the blade 2 is preloaded in one direction (from the thrust bearing 4b5 to the thrust bearing 4b4 direction), and the axial direction is further increased. Vibration can be reduced.

Here, the preload is applied in the right direction in the drawing, but the preload may be applied in the left direction in the drawing, and the preload direction is not particularly limited.

FIG. 9 shows a fifth embodiment. FIG. 10 shows FIG.
7 shows a CC sectional view of FIG. In the present embodiment, the above-mentioned second
Differences from the embodiment are as follows.

This embodiment differs from the second embodiment in that a taper land bearing having the thrust bearing 4b and a tapered portion 4b6 formed on the sliding surface is provided on the inner peripheral side B1. The taper portion 4b6 communicates with the groove portion 4b7 and extends in the circumferential direction.
Is being processed. The seal portion 5b5 also serves as the land portion. According to the present invention, since dynamic pressure is generated in the tapered land bearing portion as the blade 2 rotates, a sufficient load capacity can be obtained even if the thrust bearing is provided at this position.

FIG. 11 shows a sixth embodiment. This embodiment is different from the above-mentioned first embodiment in the following points.

In this embodiment, the bearing on one side is formed by the radial bearing 4a which is a sliding bearing, and the bearing on the other side is formed by the radial bearing 4a which is a sliding bearing and the thrust bearing 9 arranged in parallel therewith. In addition, only the seal portion 5b6 is provided between one side surface of the blade 2 and the fixed portion, and the seal portion 5b7 and the thrust bearing 4b are provided between the other side surface and the fixed portion, which is different from the first embodiment. To do.

According to the present invention, the load capacity of the thrust bearing 4b is larger than that of the thrust bearing 9, so that the blade 2 is preloaded in one direction (from the thrust bearing 4b to the thrust bearing 9). It is effective in reducing vibration in the axial direction. Further, in the case of the double-suction centrifugal pump, since the shape of the blades 2 is symmetrical, the axial thrust load is small, and the small thrust bearing 9 arranged at the shaft end has sufficient load capacity. Thrust bearing 9 provided at the shaft end
Since the stirring loss can be reduced as compared with the case where the diameter is provided in the blade 2 portion, it is effective in improving pump efficiency.

[0039]

According to the present invention, it is possible to obtain a highly reliable double suction centrifugal pump which is maintenance-free and can be stably operated for a long period of time, and which is capable of preventing damage due to uneven contact of the radial bearing.

Further, according to the present invention, it is possible to obtain a double-suction centrifugal pump which is maintenance-free and which is capable of reducing vibration during high-speed rotation, downsizing the pump, and improving efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a double-suction centrifugal pump according to a first embodiment of the present invention.

2 is a thrust bearing of the double-suction centrifugal pump of FIG. 1,
It is a front view of a seal part.

3 is a cross-sectional view of the thrust bearing and the seal portion taken along the line aa of FIG.

FIG. 4 is an explanatory diagram of pressure distribution of a thrust bearing and a seal portion of the present invention.

FIG. 5 is a front view of a thrust bearing and a seal portion of a double-suction centrifugal pump according to a second embodiment of the present invention.

6 is a bb sectional view of the thrust bearing and the seal portion of FIG.

FIG. 7 is a vertical sectional view of a double-suction centrifugal pump according to a third embodiment of the present invention.

FIG. 8 is a vertical sectional view of a thrust bearing and a seal portion of a double-suction centrifugal pump according to a third embodiment of the present invention.

FIG. 9 is a front view of a thrust bearing and a seal portion of a double-suction centrifugal pump according to a fourth embodiment of the present invention.

10 is a cross-sectional view of the thrust bearing and the seal portion taken along the line CC in FIG.

FIG. 11 is a vertical sectional view of a double-suction centrifugal pump according to a fifth embodiment of the present invention.

[Explanation of Codes] 1 ... Pump main shaft, 2 ... Blades, 3 ... Pump casing, 3
a, 3b ... Bearing support part, 4a ... Radial bearing, 4b ... Thrust bearing, 5b ... Seal part, 4b1, 4b3, 4b4
... grooves, 4b2, 4b5 ... taper part, 6 ... casing cover, 7 ... seal, 8 ... coupling part, 9 ... axial end thrust bearing, 1010a ... thermoplastic resin material.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04D 29/66 F04D 29/66 A F16J 15/18 F16J 15/18 C (72) Inventor Hideki Akiwa Ibaraki Prefecture 603 Kintate-cho, Tsuchiura City Industrial Machinery Systems Division, Hitate Manufacturing Co., Ltd. (72) Inventor Kazuo Amano 603 Kintate-cho, Tsuchiura City, Ibaraki Pref. CA15 CA21 CA46 CA54 CA58 DA11 DA13 3J043 AA17 BA04 CA03 CA12 CB13 DA01 DA05

Claims (6)

[Claims] 1. A pump main shaft having fixed blades, a pump casing that surrounds the outer circumference of the blades to form a water passage, and bearings that support the pump main shaft on both sides of a portion to which the blades are fixed. In a double-suction centrifugal pump, the bearings provided on both sides are formed by radial bearings consisting of sliding bearings, and seals and thrust bearings are formed between both side surfaces of the blade and the fixed portion, and the pump is used as a lubricant for all the bearings. A double-suction centrifugal pump characterized by using pumped water. 2. The double-suction centrifugal pump according to claim 1, wherein the sliding parts of the radial bearings are made of a thermoplastic resin. 3. The double-suction centrifugal pump according to claim 2, wherein a sliding portion of the thrust bearing is formed of a thermoplastic resin. 4. The double-suction centrifugal pump according to claim 3, wherein the sliding portion of the seal portion is formed of a thermoplastic resin, and pumped water of the pump is used as a lubricant for the seal portion. Double suction centrifugal pump. 5. The double-suction centrifugal pump according to claim 2, 3 or 4, wherein the sliding portion and the sealing portion of the bearing are made of polyetheretherketone resin or polyphenylene sulfide resin. Double suction centrifugal pump. 6. A pump main shaft having fixed blades, a pump casing that surrounds the outer periphery of the blades to form a water passage, and bearings that support the pump main shaft on both sides of the portion to which the blades are fixed. In the double-suction centrifugal pump, the bearing on one side is formed by a radial bearing consisting of a sliding bearing, and the bearing on the other side is formed by a radial bearing consisting of a sliding bearing and a thrust bearing arranged in parallel with the radial bearing. Only the seal part is provided between one side surface and the fixed part, the seal part and the thrust bearing are provided between the other side surface and the fixed part, and the both radial bearings, the thrust bearing, and the sliding part of the seal are formed of thermoplastic resin. A double-suction centrifugal pump characterized by using pumped water as a lubricant for all these bearings and seals.