JPS63277888A - Vertical type canned motor pump - Google Patents

Abstract

PURPOSE:To reduce a loss in a bearing part, by respectively providing a spiral- grooved dynamic pressure thrust bearing between a rotor and an impeller and a spiral-grooved dynamic pressure radial bearing in a main shaft in a side opposite to the impeller, in a vertical type pump. CONSTITUTION:A vertical type canned motor pump provides a thrust bearing 11 and a radial bearing 12 between an impeller 4 and a rotor 1 and a radial bearing 13 in a side opposite to the impeller. The bearings 11-13 are formed respectively as the spiral-grooved dynamic pressure bearing which forms a groove for generating a dynamic pressure in a ceramic sintered member. Accordingly, the pump, as far as it rotates, supports a rotary unit by a fluid film enabling a loss in a bearing part to be less decreased.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a canned motor pump.

[Conventional technology]

FIG. 9 is a sectional view of an example of a conventional canned motor pump disclosed in Japanese Patent Publication No. 49-38641.

In the figure, the rotor 1 and stator 2 of the motor are covered with a rotor can 32 and a stator can 33 made of stainless steel, so that the iron core, coil, and secondary conductor do not come into contact with the conveyed liquid.

An impeller 4 is screwed to the tip of the main shaft 3 of the motor, and the main shaft 3 is rotatably supported by a radial bearing 5.6 between the impeller 4 and the rotor 1 and at the end of the rotor 1. The resulting axial thrust is supported by thrust bearings 7 on both sides of the rotor l.

The conveyed liquid flows from the discharge port side to the end side of the motor through the conduction pipe 9 connected from the discharge port 8 of the pump to the end of the motor, and further flows out to the back of the impeller 4. The carrier liquid lubricates the bearing and cools the motor, and the carrier liquid is handled in a state completely isolated from the outside air.

[Problems to be solved by the invention]

Canned motor pumps are employed in cases where it is undesirable for the conveyed liquid to come into contact with the outside air, such as in food products, medicines, toxic liquids, LPG, ultrapure water, and the like.

Therefore, compared to general pumps, the overall structure is sealed and often cannot be disassembled or inspected in detail.In the case of this type of pump, as long as it is operated normally, the casing 10, impeller 4, and motor are There are few failures originating from the rotor 1 and stator 2, and most failures are due to bearing wear.

If the purpose is to prevent the conveyed liquid from leaking outside, wear of the bearing simply shortens the life of the pump, but when conveying food, medicine, or ultrapure water, If this is the case, wear of the bearings may contaminate the conveyed liquid or cause it to deteriorate due to heat, which is not desirable.

Furthermore, considering the reason for adopting a canned motor pump, it is not desirable to repeatedly disassemble and assemble the pump, even if the bearing is simply repaired.

In addition, in the case of a canned motor pump, a load is particularly applied to the thrust bearing, which often causes problems due to wear.

In view of the current situation, the present invention aims to provide a vertical canned motor pump with excellent durability.Furthermore, the present invention provides a vertical canned motor pump that does not substantially contaminate the conveyed liquid. It is an object of the present invention to provide a vertical canned motor pump that prevents local heat generation in the bearing portion and prevents thermal deterioration of the conveyed liquid. It is something.

[Means to solve the problem]

The present invention provides a canned motor pump in which an impeller is provided at one end of a rotor shaft of a vertical motor, and the motor is cooled and the bearing is lubricated by the pump's conveyed liquid itself. A rotating-side thrust support plate fixed to the rotor shaft and having a ceramic rotating-side thrust receiving surface facing downward and perpendicular to the axis; A fixed side thrust support plate having a receiving surface is provided, and a spiral groove for generating dynamic pressure is formed on either one of the facing rotating side thrust receiving surface and the stationary side thrust receiving surface to support downward thrust. A spiral dynamic pressure thrust bearing is formed, and a spiral groove dynamic pressure radial bearing is formed between the inner circumferential surface of the stationary side thrust support plate and the rotor shaft, and a shaft end of the rotor shaft on the opposite side of the impeller The present invention is a vertical canned motor pump characterized by having a spiral groove dynamic pressure bearing formed therein.

(Function) In the vertical canned motor pump of the present invention, the rotating body consisting of the rotor and the impeller is supported by a spiral groove bearing made of a ceramic sintered body.
When the motor rotates, a fluid film is formed in an extremely short period of time, and the rotating body continues to rotate stably and smoothly without solid contact, even on the thrust bearing, which is particularly loaded.

In addition, if the temperature of the stator and rotor rises and thermal expansion occurs when power is applied to the motor, the thrust bearing will be able to move between the rotor and the impeller. Since the rotor is provided on the opposite side of the impeller and is supported by a radial bearing, it has a structure that can freely respond to differences in thermal expansion.

〔Example〕

FIG. 1 is a sectional view of a vertical canned motor pump according to an embodiment of the present invention.

In FIG. 1, the rotor 1 and stator 2 of the motor are covered with rotor cans 32 and stator cans 33, which are stainless steel plates, respectively, to prevent the conveyed liquid from being contaminated. A thrust bearing 11 is provided between the impeller 4 and the rotor 1 as a stationary thrust support plate. The inner peripheral surface of the thrust bearing 11 is a radial bearing I
2, and a radial bearing 13 is also provided at the end of the rotor 1 on the side opposite to the impeller.

These bearings 11, 12, and 13 all form part of a spiral groove dynamic pressure bearing, which is a ceramic sintered body with grooves for generating dynamic pressure, and when the motor rotates, the rotating body comes into solid contact. It is supported by dynamic pressure without any stress. A connecting portion of a conductive pipe (not shown) is located at a position (not shown) in the flow path of the discharge port 8 of the pump, and communicates with a screw hole 15 formed in the end casing 14 of the motor.

Therefore, the discharge pressure increases as the pump rotates, and the conveyed liquid is led out from the discharge port 8 and flows into the motor, passing through the radial bearing 13 at the end, the rotor 1, the stator 2, the thrust bearing 11, and the radial bearing 12. Then, it is circulated again inside the pump casing lO, where the bearings are lubricated and the motor is cooled.

Next, the structure of the bearing that is characteristic of the present invention will be described. The bearings 11, 12, and 13 used in the figure are all part of a spiral groove dynamic pressure bearing that uses a hard ceramic sintered body with spiral grooves for generating dynamic pressure formed on the surface. There is.

Regarding the radial bearing 13, the surface of the ceramic shaft sleeve 17, which is fixed to the main shaft 3 by shrink fitting or NAND, is finished into a smooth cylindrical surface, and a herringbone-shaped movement is formed on the surface by shot blasting as a spiral groove. A cylindrical ceramic bearing 13 is provided with pressure generating grooves and a smooth inner surface on the fixed side.

Therefore, when the main shaft 3 rotates, the bearing 13 and shaft sleeve 17
A fluid film of the carrier liquid is formed between the two and the rotating body rotates without solid contact.

Figure 2 shows the thrust bearing 1 installed at the end of the rotor 1.
FIG. 3 is an enlarged cross-sectional view of No. 3.

The inner peripheral surface of the bearing 13 made of a ceramic sintered body is finished in a smooth cylindrical shape, and the shaft sleeve 17 is also finished in a smooth cylindrical surface with a spiral groove about 10 μm deep for generating dynamic pressure. Herringbone groove 1 as
8 is formed by shot blasting. The outer diameter of the shaft sleeve 17 is 20 to 50 μm larger than the inner diameter of the bearing 13.
It has small dimensions and is movable in the direction of the bearing 13. That is, even if a temperature difference occurs between the rotor 1 and the stator 2 when power is applied to the motor, there will be no substantial trouble.

Furthermore, the thrust bearing 11 will be described.

21 is a rotating ceramic sintered body that is fixed to the main shaft 1, which is a rotor shaft, between the rotor 1 and the impeller 4, and has a rotating side thrust receiving surface that is perpendicular to the axis and faces downward. A thrust bearing 11 made of a hard ceramic sintered body serving as a fixed side thrust support plate, which is a disk and has a fixed side thrust receiving surface on the upper surface facing the rotating disk 21, is connected to the adapter ring 26 by the back plate 25. A fixed arrangement is provided to form a thrust bearing.

In this embodiment, a spiral groove for generating dynamic pressure is provided on the upper surface of the thrust bearing 11, and the thrust bearing 11 and the rotating disk 21 form a spiral groove dynamic pressure thrust bearing.

A rotating disk 23 is provided as a rotation-side thrust support plate, facing the lower surface of the thrust bearing 11 and fixed to the main shaft 3. When the pump is started, a temporary upward thrust is generated, and this temporary upward thrust is received by the thrust bearing formed by the lower surface of the thrust bearing 11 and the upper surface of the rotating disk 23. A spiral groove for generating dynamic pressure may be provided on the lower surface of the thrust bearing 11. This upward thrust is small and short-lived, so
As shown in the figure, the thrust receiving area may be reduced by making the diameter smaller than that of the upper rotary disk 21. Also, instead of providing a spiral groove for generating dynamic pressure, a simple groove for lubricating fluid may be provided.
It can remain flat.

A rotating disk 21 made of a ceramic sintered body is provided with a back plate 19 fixed to the main shaft 3 and serving as a shaft sleeve through an elastic body 20 such as Delrin plastic, and the rotating disk 21 and thrust bearing 11 are connected to each other. In between, it supports the downward thrust load due to its own weight and the fluid force generated from the rotor I toward the impeller 4 during steady operation. Also,
A small-diameter rotating disk 23 made of a ceramic sintered body positioned at a predetermined dimension via the shaft sleeve 16 and elastic bodies 20' and 20'' to support a thrust load from the opposite direction is mounted on a metal back plate 24. Therefore, the upward thrust load from the impeller 4 toward the rotor 1 that occurs when the pump is started is counteracted by the fluid film between the thrust bearing 11 on the stationary side and the rotating disk 23. It is.

FIG. 3 shows the pattern of grooves for generating dynamic pressure on the surface of a loaf example of the thrust bearing 11.
are formed in large numbers. 29 is a land, and the depth of the groove 28 is about 3 to 50 μm, and the suitable groove depth is determined depending on the viscosity of the conveyed liquid. The two-dot chain line 21 indicates the position T of the outer peripheral edge of the rotating disk 21, the two-dot chain line 26 indicates the position of the inner peripheral edge of the adapter ring 26, and the outer end of the groove 28 is located between the two-dot chain lines 21 and 26. It's open. An arrow 27 indicates the direction of rotation of the rotating disk 23 (ie, the main shaft 3).

The center of the thrust bearing is an opening through which the shaft passes.

When the pump starts up, the first upward thrust generated is received by the thrust bearing formed by the lower surface of the thrust bearing 11 and the upper surface of the rotating disk 23. During steady operation, a downward thrust is generated due to its own weight and fluid force, but when the thrust bearing 11 and the rotating disk 21 approach each other due to this downward thrust, the fluid on the outer periphery moves toward the center due to the action of the dynamic pressure generating groove 2B. Dynamic pressure is generated between the thrust bearing 2 and the rotating disk 21, and the rotating body rotates without solid contact.

A shaft sleeve 16 is fitted on the outside of the cylindrical portion of the back plate 19, facing the inner peripheral surface of the thrust bearing 11. The shaft sleeve 16 is made of a hard ceramic sintered body, and has a smooth cylindrical surface finished with a herringbone groove as a spiral groove for generating dynamic pressure with a depth of about 10 IIm by shot blasting. (such as 18 in FIG. 2) is formed. On the other hand, the inner peripheral surface of the thrust bearing 11 made of a ceramic sintered body is finished into a smooth cylindrical shape. The outer diameter of the shaft sleeve 16 is smaller than the inner diameter of the thrust bearing 11 by about 20 to 50 μm, and the outer peripheral surface of the shaft sleeve 16 and the inner peripheral surface of the thrust bearing 11 form a spiral groove dynamic pressure radial bearing. ing.

Regarding the structure of each part constituting the spiral groove dynamic pressure thrust bearing and the radial bearing, as shown in FIG. 21, elastic body 20°, shaft sleeve 16,
The elastic body 20, the rotating disk 23, and the elastic body 20 are arranged in a stacked manner. Reference numeral 34 denotes a key bound to the keyway 35, which fits into a notch (not shown) provided at the end of the cylindrical portion of the back plate 19 on the impeller side, and is provided on the inner periphery of the back plate 24. The rear plate 19, 24 is fitted into a key groove (not shown) to transmit torque to the rear plate 19, 24, and rotate them together with the main shaft 3. The back plate 19 is the impeller 4
The back plate 24 is axially fixed to the main shaft 3 via a key 34 and an impeller 4.

Since the rotating disks 21 and 23 are ceramic sintered bodies, if a keyway is used on the inner periphery to receive torque from the back plate 19.24, cracks are likely to occur. As shown in the figure, torque is transmitted using the elastic body 20 sandwiched between the two.

That is, the elastic body 20 is provided with protrusions 36 shown in FIG. 8
Fit as shown in the figure to transmit torque. The structure between the rotating disk 23 and the back plate 24 is similar. In addition, rotating disk 2
1. There is also an elastic body 2 between the shaft sleeve 16 and the rotating disk 23.
0'' and 20' in a similar structure. In this way, the rotating disk 19, 23 and the shaft sleeve 16 rotate together with the main shaft 3. Note that the relationship between the concave and convex portions may be reversed. .

The elastic bodies 20.20' and 20'' alleviate manufacturing errors and assembly errors of the back surface Fi, 19.24, rotation!2-plate 21.23, shaft sleeve 16, and thrust bearing 11 by their elastic deformation, and the thrust bearing It has the effect of smoothing the movement of the surface, but in addition to this, by configuring it as described above, it can be combined with the rotating disk 21, 23 of the ceramic sintered body in a shape that is less likely to cause stress concentration. , elastic deformation can reduce impact and prevent cracking and destruction of ceramics.

The preferred hard ceramic sintered body is SiC.
Sintered body, A 1.0. These include sintered bodies, 5i3Na sintered bodies, and the like. When constructing a thrust bearing or a radial bearing using these materials, the surfaces that rub against each other are first made into smooth planes or cylindrical surfaces of a predetermined shape, and then the areas corresponding to the lands are covered with resin and shot blasted. By doing so, desired grooves for generating dynamic pressure are formed.

Although it depends on the viscosity of the conveyed liquid, taking water as an example, it is desirable that the entire surface of the thrust bearing 11 and the opposing rotating disks 21 and 23 have a waviness of 1 μm or less, and the maximum surface It is also desirable that the roughness of the land (smooth surface) be 0.3 μm or less.

In the embodiment shown in FIG. 2, the groove 28 for generating dynamic pressure is formed on the thrust bearing 11, but it may also be formed on the surface of the rotating disk 21, 23, in which case both surfaces of the thrust bearing are smooth surfaces. Therefore, i1!28 for dynamic pressure generation is not formed.

In addition, a spiral pattern in which the fluid flows out from the center toward the outer periphery along the spiral groove can also be used.
It is possible to achieve exactly the same effects. The outer edge of this poem is closed by a land to prevent dynamic pressure from escaping.

If the directions of the spiral grooves are selected so that when the main shaft 3 rotates, the flow of fluid on both sides of the thrust bearing 11 is toward the center on one side and toward the outer periphery on the other side, a spiral groove dynamic pressure thrust bearing can be formed. The flow flows through smoothly, increasing the lubrication effect and dynamic pressure stopping effect, as well as 2it! By increasing the cooling effect of each part, the cooling effect of each part is increased.

Also in the radial bearing 12.13, the shaft sleeve 16.
The outer circumference of 17 may be made smooth and a herringbone groove may be provided on the inner surface of radial bearing 12.13.

No matter which side of the radial bearing 12.13 or the shaft sleeve 16.17 the herringbone groove is provided, if it is made asymmetrical so that the flow has directionality with respect to the axial direction, the cooling fluid can be You can choose the direction of the flow. For example, the flow can be directed from the radial bearing 13 to the rotor 1, from the stator 2 to the thrust bearing 11, from the radial bearing 12 to the thrust bearing 11, to the impeller 4, or by providing a fluid outlet between the stator 2 and the thrust bearing 11, Bearings 13 - rotor 1, stator 2 → flow path serving as outlet and back of impeller 4 → thrust bearing 11 → radial bearing 12
- Thrust bearing 11-i outlet passages may be provided in parallel to allow low-temperature fluid to pass through the radial bearing 12 and thrust bearing 11 without passing the high-temperature fluid that has passed through the rotor 1 and stator 2.

The thrust bearing 11 is not integrally made of ceramic, but may be formed by fixing ceramic plates to both surfaces and the inner peripheral surface of a metal disk using an adhesive, brazing, or the like.

Note that the through hole 38 provided in the radial bearing 13 and the through hole 3I formed in the thrust bearing 11 are flow paths through which the conveyed liquid circulates inside the motor, ensuring the flow rate of the liquid necessary for cooling the motor. It is for the purpose of

〔Effect of the invention〕

The vertical canned motor pump of the present invention includes a bearing that combines a spiral groove dynamic pressure thrust bearing using a ceramic sintered body and a radial bearing between the rotor of the motor and the impeller, and the side of the rotor opposite to the impeller. The main shaft of the pump is also equipped with a spiral driven pressure radial bearing that uses a ceramic sintered body, so not only radial bearings with low loads, but also thrust bearings with heavy loads can be used to prevent the pump from rotating. As long as the rotating body is supported by the fluid film. Therefore, the loss of the bearing part is not only extremely small, but there is virtually no damage to the bearing part, so there is no need to repair the bearing part of a canned motor pump, which was required in the past.Furthermore, the bearing part does not have solid sliding. Therefore, heat generation is extremely low, and even if the conveyed liquid is easily altered by heating, it can be transported stably.Furthermore, since there is no solid sliding, the pump itself generates abrasion powder and the conveyed liquid is Furthermore, even if there is thermal expansion of the motor, it can escape through the IJ free end radial bearing, so it can be used under a wide range of temperature conditions, making it extremely useful in practice. be.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of a spiral groove dynamic pressure radial bearing, Fig. 3 is a plan view of the spiral groove of a thrust bearing, and Fig. 4 is a vicinity of the rotating disk. 5.6.7.8 are the longitudinal sectional views of 1. and 1. of FIG. 4, respectively.
A cross-sectional view along lines II, ■, and ■, and FIG. 9 are a longitudinal cross-sectional view of the conventional example. 1... Rotor, 2... Stator, 3... Main shaft, 4
... Impeller, 5... Radial bearing, 6... Radial bearing, 7... Thrust bearing, 8... Discharge port,
9... Conduction vibe, 10... Casing, 11...
・Thrust bearing, 12... Radial bearing, 13...
Radial bearing, 14... End casing, 15...
・Screw hole, 16... Shaft sleeve, 17... Shaft sleeve, 18... Groove, 19... Back plate, 20... Elastic body, 21... Rotating disk, 23... Rotating disk, 24・
... Back plate, 25... Back plate, 26... Adapter ring, 27... Rotation direction, 28... Dynamic pressure generation groove, 2
9... Land, 31... Through hole, 32... Rotor can, 33... Stator can, 34... Key,
35...Keyway, 36...Protrusion, 37...Recess 3
8...Through hole.

Claims (2)

[Claims] (1) In a canned motor pump that includes an impeller at one end of the rotor shaft of a vertical motor and cools the motor and lubricates the bearings using the pump's conveyed liquid itself, the rotor is disposed between the rotor and the impeller. A rotating thrust support plate fixed to the shaft and having a downwardly facing ceramic rotating thrust bearing surface perpendicular to the axis, and a fixed ceramic fixed thrust bearing located opposite to the rotating thrust bearing surface on the upper surface. a fixed side thrust support plate having a surface, and a spiral groove for generating dynamic pressure is formed on either one of the facing rotating side thrust receiving surface and the stationary side thrust receiving surface to support downward thrust. A spiral dynamic pressure thrust bearing is formed, a spiral groove dynamic pressure radial bearing is formed between the inner circumferential surface of the stationary side thrust support plate and the rotor shaft, and a spiral groove dynamic pressure radial bearing is formed at the shaft end of the rotor shaft on the opposite side of the impeller. A vertical canned motor pump characterized by being equipped with a spiral groove dynamic pressure bearing. (2) In a canned motor pump that is equipped with an impeller at one end of the rotor shaft of the vertical motor and cools the motor and lubricates the bearings using the pump's conveyed fluid itself, the rotor is disposed between the rotor and the impeller. A rotating side thrust support plate fixed to the shaft and having a pair of ceramic rotating side thrust receiving surfaces that are perpendicular to the axis and facing each other; A fixed-side thrust support plate having a fixed-side thrust receiving surface is provided, and a spiral groove for generating dynamic pressure is formed on either one of the facing rotating-side thrust receiving surface and the fixed-side thrust receiving surface, so that they mutually Two sets of spiral dynamic pressure thrust bearings are formed to support thrust in opposite directions, a spiral groove dynamic pressure radial bearing formed between the inner circumferential surface of the stationary side thrust support plate and the rotor shaft, and the rotor shaft. A vertical canned motor pump characterized by comprising: a spiral groove hydrodynamic bearing formed at the shaft end on the opposite side of the impeller.