JP7688568B2 - pump - Google Patents

Description

The present invention relates to a pump that includes a closed impeller having multiple blades between a first plate and a second plate, a rotating shaft to which the impeller is rotatably connected, and a casing that houses the impeller and the rotating shaft.

Reducing the amount of fluid leakage from the sliding parts of closed impellers against the casing of pumps, etc. has long been an issue, and various approaches have been considered.

In general, as shown in the following Patent Document 1 and Non-Patent Document 1, for example, it is common to provide a sliding gap in the annular part in the axial direction. In order to suppress the amount of leakage, it is necessary to increase the pressure loss caused by the pressure difference between the inlet and outlet of the sliding part, so the sliding gap formed in the annular shape is made longer in the axial direction or a labyrinth structure is adopted.

Japanese Utility Model Application Publication No. 56-156999

Japanese Industrial Standards JIS B8327:2013 (Figure C.1 Example of annular gap shape)

The sliding parts of conventional pumps shown in Patent Document 1 and Non-Patent Document 1 have a complex shape because they use a labyrinth shape.

In addition, a centrifugal pump is prone to uneven loads in the radial direction, and as the load increases, the impeller is more likely to rotate beyond the sliding clearance. Narrowing the sliding clearance can reduce leakage, but on the other hand, it can cause the sliding parts to come into contact, resulting in vibration and an increase in shaft power; this tendency can be particularly pronounced when a labyrinth shape is used.

In addition, if the leakage flow path is complicated, such as a labyrinth shape, the properties of the fluid being pumped, for example, if foreign matter is mixed in the fluid, may cause the foreign matter to get caught, leading to wear and corrosion in the sliding parts, and the sliding gap may become larger, increasing the amount of leakage.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a pump that can reduce the amount of leakage without complicating the shape of the pump's sliding parts.

A feature of the pump according to the present invention is that the pump is capable of delivering a liquid and includes a closed-type impeller having a plurality of blades between a first plate and a second plate, a rotating shaft to which the impeller is rotatably coupled, and a casing that houses the impeller and the rotating shaft,
The impeller has a seal portion at one end of the main body portion having a diameter larger than the outer diameter of the main body portion, and the sliding gap between the seal surface of the seal portion and the casing extends in the radial direction of the rotating shaft and has a linear shape from one end to the other end in a longitudinal section .

According to this configuration, the impeller has a seal part at one end of the main body part that has a diameter larger than the outer diameter of the main body part, and the sliding gap between the seal surface of the seal part and the casing extends in the radial direction of the rotating shaft. Therefore, the leakage flow direction, combined with the direction against the centrifugal force, can effectively prevent leakage of fluid while ensuring a sufficient sliding gap.

Furthermore, because the sliding gap has a linear shape extending in the radial direction, it is simpler and less complicated in shape than the conventional configuration that employs a labyrinth shape. Also, the leakage flow direction is against the centrifugal force, which increases the effect of suppressing the amount of leakage, so it is possible to provide a sufficient sliding gap, and even if the impeller rotates, it is possible to avoid vibrations and an increase in shaft power due to contact with the impeller.

In addition, because the shape of the sliding gap is simple, foreign matter is less likely to get caught in the gap, even if the fluid being pumped out is, for example, a slurry containing foreign matter. As a result, wear and corrosion are less likely to occur in the sliding parts, so there is no risk of the sliding gap becoming larger and the amount of leakage increasing. In the unlikely event that wear does occur, the sliding gap can be reset appropriately by shifting the rotating shaft.

In the pump according to the present invention, it is preferable that the sealing surface is aligned in a direction perpendicular to the axis of the rotating shaft.

According to this configuration, the seal portion has a seal surface that runs along a direction perpendicular to the axis of the rotating shaft. Therefore, even if the impeller rotates with some wobble in a direction perpendicular to the axis of the rotating shaft, unlike the sliding gap of a conventional labyrinth shape, the sliding gap can be widened while maintaining the effect of suppressing leakage, and the risk of contact with the rotation of the impeller in the radial direction can be more reliably reduced.

In the pump according to the present invention, it is preferable that the extension portion of the sealing portion that protrudes radially outward from the main body portion has an uneven surface.

With this configuration, the extended portion of the seal portion has an uneven surface, which makes it difficult for fluid to flow along the uneven surface of the seal portion. As a result, it is difficult for a circulating flow of fluid to occur, and the efficiency of fluid delivery can be improved.

In the pump according to the present invention, it is preferable that the extension portion of the seal portion that protrudes radially outward from the main body portion has a portion that extends along the outer surface of the main body portion of the impeller.

With this configuration, the expansion of the seal portion has a portion that extends along the outer surface of the main body of the impeller, making it difficult for a circulating flow of the fluid to occur, thereby improving the efficiency of fluid delivery.

In the pump according to the present invention, it is preferable that the sealing surface has an uneven surface.

With this configuration, the seal surface of the seal portion has an uneven surface, making it difficult for the fluid to pass through the sliding gap (leakage flow path), so leakage of the fluid can be more reliably prevented.

In the pump according to the present invention, it is preferable that the seal portion is configured separately from the main body portion of the impeller.

With this configuration, the seal portion is constructed separately from the main body of the impeller, making it easier to carry out maintenance work such as replacing the seal portion. Furthermore, by preparing multiple seal portions with different thicknesses, it becomes easier to adjust the size of the sliding gap.

1 is a partial cross-sectional view of a centrifugal pump to which the present invention is applied. FIG. 2 is an enlarged view of a main part of FIG. 1 . FIG. 11 is a partial cross-sectional view of a volute pump according to another embodiment. FIG. 11 is a partial cross-sectional view of a volute pump according to another embodiment. FIG. 11 is a partial cross-sectional view of a volute pump according to another embodiment.

An embodiment of the pump according to the present invention will be described with reference to the drawings.

In this embodiment, the pump according to the present invention is described as being used in a centrifugal pump, but the pump according to the present invention is not limited to this centrifugal pump and can also be used in other pump structures.

As shown in FIG. 1, the volute pump 1 in this embodiment includes a closed impeller 2, a vertically extending rotating shaft 3 to which the impeller 2 is rotatably connected, and a casing 4 that houses the impeller 2 and the rotating shaft 3.

The rotating shaft 3 is rotatably supported on the casing 4, and the impeller 2 is integrally connected to the rotating shaft 3 by a key.

A prime mover such as an electric motor (not shown) is engaged with the rotating shaft 3, and the impeller 2 is rotated by the driving force of the prime mover. In the pump of this embodiment, the rotating shaft 3 is provided along the vertical direction, so the impeller 2 rotates along a horizontal plane that crosses the rotating shaft 3. Note that, although the rotating shaft 3 in this embodiment is provided along the vertical direction, this is not limited to this configuration, and the rotating shaft 3 may also be provided along the horizontal direction.

The impeller 2 in this embodiment is composed of a main body portion and an annular seal portion 5.

The main body portion has a disk-shaped upper plate 20 (an example of a first plate) located on the upper side in the axial direction, a disk-shaped lower plate 21 (an example of a second plate) located on the lower side in the axial direction, and a number of blades 22 provided between the upper plate 20 and the lower plate 21 to connect them to each other. Although not shown, the multiple blades 22 are each formed so as to spread out radially from the center in the radial direction.

A suction port 23 having a cylindrical inner surface is formed on the lower surface 25 of the main body, and a discharge port 24 is provided axially above the main body. A flow path through which the fluid flows is formed between the suction port 23 and the discharge port 24.

The seal portion 5 has a larger outer diameter in the radial direction of the impeller 2 than the underside 25 of the main body portion of the impeller 2, and the portion that protrudes laterally outward (radially outward) from the main body portion is called the extension portion 50.

As shown in FIG. 2, the seal portion 5 in this embodiment is configured separately from the main body portion of the impeller 2 and is fixed to the underside 25 of the main body portion by bolts or the like. However, this configuration is not limited, and the seal portion 5 may be configured integrally with the main body portion of the impeller 2. In any case, the seal portion 5 is configured to be provided at the lower end of the main body portion of the impeller 2.

The seal portion 5 of the impeller 2 constitutes the sliding portion of the impeller 2 relative to the casing 4, and the bottom surface of the seal portion 5 forms the seal surface 51.

That is, the impeller 2 has a seal portion 5 at the lower end of the main body portion, the seal portion 5 having a diameter larger than the outer diameter of the main body portion, and the sliding gap S1 between the seal surface 51 of the seal portion 5 and the casing 4 extends in the radial direction of the rotating shaft 3.

In this embodiment, the sealing surface 51 is provided along a direction perpendicular to the axis of the rotating shaft 3, but this is not necessarily limited to this configuration.

The casing 4 is provided with an annular liner member 40 having an outer diameter similar to that of the seal portion 5. The liner member 40 is disposed below and facing the seal portion 5, and a sliding gap S1 is provided between the seal portion 5 and the liner member 40.

A circular space S2 is formed between the casing 4 and the lower plate 21 of the impeller 2.

When the impeller 2 rotates due to the driving of the rotating shaft 3, the fluid to be pumped is sucked in through the suction port 23 and discharged through the discharge port 24, as shown by the arrow in Figure 2.

At this time, the rotational energy of the impeller 2 is applied as a centrifugal force to the fluid flowing inside, and the rotational energy of the impeller 2 is converted into pressure energy and kinetic energy, so that the pressure of the fluid on the discharge port 24 side becomes relatively higher than the pressure of the fluid on the suction port 23 side.

As a result, some of the fluid discharged from the discharge port 24 may pass through the annular space S2 toward the sliding gap S1, and leak out through the sliding gap S1 (leakage flow path) into the flow path where the suction port 23 is located.

However, in the pump of this embodiment, the seal portion 5 of the impeller 2 forms a seal surface 51 that extends in the radial direction, which lengthens the leakage flow path and thereby prevents fluid leakage.

Furthermore, because the sliding gap S1 has a linear shape extending in the radial direction, the shape is simpler and less complicated than the conventional configuration that employs a labyrinth shape. As a result, the impeller 2 is less likely to rotate in the sliding gap S1, and vibrations and increases in shaft power due to contact with the impeller 2 are also suppressed.

In addition, because the shape of the sliding gap S1 is simple, foreign matter is less likely to get caught in the gap, even if the fluid being pumped out is, for example, a slurry containing foreign matter. As a result, wear and corrosion are less likely to occur in the sliding parts, and there is no risk of the sliding gap S1 becoming larger and the amount of leakage increasing.

Other embodiments
If the size or structure of the pump makes it impossible to secure sufficient space near the impeller 2 inside the casing 4, contact between the expansion portion 50 of the seal portion 5 and the leaking fluid may cause a circulating flow or stirring, resulting in an increase in the shaft power of the pump. In this case, for example, a structure for suppressing the increase in shaft power may be added to the seal portion as follows.

(1) As shown in FIG. 3, in order to prevent the flow of fluid along the sealing portion 5 in the annular space S2, the expansion portion 50 of the sealing portion 5 may be configured to have an uneven surface.

(2) As shown in FIG. 4, in order to suppress the occurrence of a circulating flow of fluid in the annular space S2, the expansion portion 50 of the seal portion 5 may be configured to have a portion that extends along the lower plate 21 (the outer surface of the main body portion) of the impeller 2.

(3) Although not shown, the expansion portion 50 of the sealing portion 5 may be configured to generate an upward flow in the annular space S2. With this configuration, since the expansion portion 50 of the sealing portion 5 is configured to generate an upward flow, it is difficult for a circulating flow of the fluid to occur above the sealing portion 5, and the efficiency of the fluid delivery can be improved.

Also, as shown in FIG. 5, the sealing surface 51 of the sealing portion 5 may be configured to have an uneven surface so that the fluid is less likely to pass through the leakage flow path.

Although the present invention has been described above with reference to the drawings, it goes without saying that the present invention is not limited to the configurations shown in the drawings, and can be embodied in various forms without departing from the spirit and scope of the present invention.

The pump according to the present invention can be suitably used, for example, as a centrifugal pump.

1 Centrifugal pump 2 Impeller 20 Upper plate (first plate)
21 Lower plate (second plate)
22 Blade 23 Suction port 24 Discharge port 25 Underside 3 Rotating shaft 4 Casing 40 Liner member 5 Seal portion 50 Expanded portion 51 Seal surface S1 Sliding gap S2 Annular space

Claims (6)

A pump capable of delivering a liquid includes a closed-type impeller having a plurality of blades between a first plate and a second plate, a rotating shaft to which the impeller is rotatably coupled, and a casing that houses the impeller and the rotating shaft,
The impeller has a seal portion at one end of the main body portion, the seal portion having a diameter larger than the outer diameter of the main body portion, and the sliding gap between the seal surface of the seal portion and the casing extends in the radial direction of the rotating shaft and has a linear shape from one end to the other end in longitudinal section . The pump according to claim 1, wherein the sealing surface is aligned in a direction perpendicular to the axis of the rotating shaft. A pump including a closed-type impeller having a plurality of blades between a first plate and a second plate, a rotating shaft to which the impeller is rotatably coupled, and a casing that houses the impeller and the rotating shaft,
the impeller has a seal portion at one end of the main body portion, the seal portion having a diameter larger than an outer diameter of the main body portion, and a sliding gap between a seal surface of the seal portion and the casing extends in a radial direction of the rotating shaft;
A pump in which an extended portion of the sealing portion that protrudes radially outward from the main body portion has an uneven surface. A pump including a closed-type impeller having a plurality of blades between a first plate and a second plate, a rotating shaft to which the impeller is rotatably coupled, and a casing that houses the impeller and the rotating shaft,
the impeller has a seal portion at one end of the main body portion, the seal portion having a diameter larger than an outer diameter of the main body portion, and a sliding gap between a seal surface of the seal portion and the casing extends in a radial direction of the rotating shaft;
A pump wherein the sealing portion has an extension portion that protrudes radially outward from the main body portion and that extends along an outer surface of the main body portion of the impeller. 5. A pump as claimed in claim 3 or 4 , wherein the sealing surface comprises a textured surface. The pump according to any one of claims 1 to 5, wherein the seal portion is configured as a separate body from the main body portion of the impeller.

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