JP2008232121A - Centrifugal pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal pump capable of reducing inconvenience caused by invasion and accumulation of foreign matter such as dirt and contamination in a gap between a pump casing and an impeller, namely, damage and pump failure or the like due to foreign matter getting into a sliding part, by a simple inexpensive means without requiring an expensive separate means. <P>SOLUTION: The centrifugal pump comprises the impeller 2, a pump casing 3 rotatably holding the impeller 2, a suction port 4 of fluid formed on a pump casing 3 opening with facing a center part of the impeller 2, a delivery port 5 of fluid formed on the pump casing 3 opening in a lateral direction to a rotary axis X of the impeller 2. The impeller 2 comprises a plurality of blades 7 arranged and formed around the axis X, and a roughly disk shape tip shroud 8 connecting and integrating the blades 7 at a suction port side ends, and is provided with a sliding part S formed over an outer circumference part tip 8A of the tip shroud 8 and the pump casing 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal pump applied to a drainage pump facility, a submersible pump, and the like.

  As a structure of this type of centrifugal pump, a vertical shaft type disclosed in Patent Document 1 is known, and an impeller, a pump casing that rotatably accommodates the impeller, a fluid suction port, And a fluid discharge port formed in the pump casing. The impeller has a plurality of blades and upper and lower shrouds that connect and integrate the blades at their upper and lower ends so as to serve as a fluid guide surface, and spans the lower end outer peripheral portion of the lower shroud and the pump casing. A sliding portion is formed.

  The sliding part is provided to maintain the pump efficiency, but foreign matter such as dust and mud mixed in the pumping target fluid such as rainwater enters the pump casing through the gap between the impeller and the pump casing. They may accumulate in the pump casing near the sliding part.

  In other words, if foreign matter such as dust enters the suction port from the gap between the outer peripheral edge of the impeller and the pump casing in the pump casing, the dust and mud that has entered once are discharged outside the casing due to the presence of the sliding part. It becomes difficult to be done and stays in the pump casing and accumulates.

Therefore, as disclosed in Patent Document 1, a pocket portion having a lowest height level is formed in the suction port portion of the pump casing, and earth and sand outflow holes communicating with the outside from the pocket portion are provided at a plurality of locations. Measures have been developed to form and provide on-off valves in these sediment outflow holes. According to this countermeasure, by opening a plurality of on-off valves at regular intervals during the operation of the pump, it accumulates in the circumferential clearance space formed in the pump casing, that is, between the pump casing and the lower shroud. Mud and garbage can be discharged regularly. Thus, it is described that it is possible to avoid damage and pump failure due to foreign matter biting into the sliding portion.
JP 2002-089482 A

  Surely, if the on-off valve is opened, the infiltrated and accumulated earth and sand can be discharged, but for that purpose, a control device including a plurality of on-off valves and their driving operation mechanisms, time-lapse means, etc. is necessary. There is a cost problem. In addition, depending on the frequency of opening and closing of the valve, until the opening and closing valve is opened, dust and foreign matter gradually accumulate in the pump casing and remain in the pump casing. There is a risk that inconvenience (damage due to foreign matter biting into the sliding portion and pump failure) cannot be resolved.

  The object of the present invention is to cause inconvenience due to accumulation of foreign matter such as mud and dust from the gap between the pump casing and the impeller and stagnating, that is, damage due to biting of foreign matter into the sliding part. An object of the present invention is to provide a centrifugal pump capable of reducing the occurrence of a pump failure by a simple and inexpensive means without providing an expensive separate means with an on-off valve or a control device.

The invention according to claim 1 includes an impeller 2, a pump casing 3 that rotatably accommodates the impeller 2, a fluid suction port 4, a fluid discharge port 5 formed in the pump casing 3, In a centrifugal pump configured with
The impeller 2 is equipped with a tip shroud 8 formed at the inlet side end, and a sliding portion S formed across the outer peripheral end 8A of the tip shroud 8 and the pump casing 3. It is a feature.

  According to a second aspect of the present invention, in the centrifugal pump according to the first aspect, the impeller 2 includes one or a plurality of blades 7 arranged around the axis X thereof, and the blades 7 are arranged at the inlet side end. A base end shroud 6 that is connected and integrated on the opposite side is formed.

  According to a third aspect of the present invention, in the centrifugal pump according to the first aspect, the impeller 2 opens in the direction of the axial center X, and the suction port 2a for sucking fluid and the lateral direction with respect to the axial center X It consists of the tubular flow path 20 provided with the discharge port 2b discharged to the inside.

  According to a fourth aspect of the present invention, in the centrifugal pump according to any one of the first to third aspects, the axial center X is directed vertically and the suction port 4 is directed downward at the lower end of the pump casing 3. The shaft center X is formed in an upright vertical type so that the discharge port 5 is formed on the lateral outer side of the pump casing 3.

  According to the first aspect of the present invention, normally, the sliding portion formed between the suction port side end portion (the inner peripheral side front end portion or the inner peripheral side front end side portion) of the front end shroud and the pump casing is provided at the front end. Since it is formed over the outer peripheral side end of the shroud and the pump casing, the sliding part is located at the end opposite to the inlet port of the tip shroud, and the inlet side end portion of the upstream tip shroud is It will be in a state to be released. Therefore, it is difficult for foreign matter such as dust and mud to enter the circumferential clearance formed between the tip shroud and the pump casing from the spiral chamber side, and foreign matter may enter. Since these foreign substances are easily discharged from the upstream end of the circumferential gap and do not stay or accumulate, inconveniences such as damage to the sliding part and pump failure are avoided. become.

  In other words, since the centrifugal pump is configured so that the upstream side of the circumferential gap portion is an open end and foreign matter can be discharged freely, foreign matter that has entered the circumferential gap portion from the high-pressure spiral chamber as in the prior art. The sliding part does not interfere with the discharge. And it becomes easy to discharge | emit from the open end by the pressure difference of a spiral chamber and a circumferential clearance part.

  As a result, inconvenience due to accumulation of foreign matter such as mud and dust from the gap between this and the impeller in the pump casing and stagnating, that is, damage to the sliding portion due to foreign matter biting into the sliding portion It is possible to provide an improved centrifugal pump that can be realized as a simple and inexpensive means without providing an expensive separate means with an on-off valve or a control device.

  The invention of claim 2 is a centrifugal pump having a closed type impeller equipped with a base end shroud in addition to a front end shroud. There is less risk of staying in or accumulating in the pump casing such as the gap portion.

  The invention of claim 3 is a centrifugal pump having an impeller comprising a tubular flow path having a suction port that opens in the axial direction and sucks fluid and a discharge port that discharges in a direction transverse to the axial center. Therefore, while ensuring the passage of large foreign matters, there is less possibility that foreign matters such as mud and dust will remain or accumulate in the pump casing such as the circumferential gap portion.

  In the case where the centrifugal pump is a vertical shaft type whose rotational axis is directed vertically as in the invention of claim 4, the sliding portion is located at the uppermost end of the circumferential gap portion. It is less likely to enter the circumferential gap portion from the side of the high-pressure spiral chamber (see FIG. 1) than the circumferential gap portion, which is a location for receiving the fluid discharged from the impeller. Even if foreign matter enters the circumferential gap portion, the lower end of the circumferential gap portion is open and is naturally discharged by gravity. There is less risk of continuing or depositing.

  Embodiments of a centrifugal pump according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of a main part of a vertical shaft type centrifugal pump, FIG. 2 is a cross-sectional view showing a seal part, and FIGS. 3 and 4 are main parts showing the spiral pumps of Examples 2 and 3 due to the difference in pump casing. FIG. 5-7 is sectional drawing of the principal part which shows another structure of a sliding part, FIG. 8 is another structural drawing of an impeller.

[Example 1]
As shown in FIG. 1, the centrifugal pump P according to the first embodiment is a vertical spiral pump P, and an impeller 2 mounted on the lower end of a vertically oriented main shaft 1 accommodated in a main body case 0, A pump casing 3 that rotatably accommodates the impeller 2, a fluid suction port 4 that is formed at the lower end of the pump casing 3 so as to open downward facing the center of the impeller 2, and the impeller 2 And a fluid discharge port 5 formed on the lateral outer side of the pump casing 3 so as to open in a lateral direction with respect to the rotational axis X. The main shaft 1 is configured to be driven and rotated by a prime mover 9 such as an electric motor or an engine.

  The impeller 2 includes a substantially disc-shaped base end side shroud 6 having a boss portion 6a bolted to the main shaft 1 so as not to rotate relative to the main shaft 1, and a plurality of pump blades 7 arranged around the shaft center X at equal angles. In addition, the pump blade 7 is configured in a closed type having a substantially disk-shaped tip shroud 8 that integrally connects and integrates the pump blades 7 at the inlet side end. The tip shroud 8 is thick and has a cross-sectional shape that is curved at 90 degrees, and is formed with a suction port 2 a for fluid suction that fits inside the suction port 4 of the pump casing 3. A state in which a plurality of discharge ports 2b surrounded by the shrouds 6 and 8 on the base end side and the front end side and the outer diameter side ends of the pump blades 7 and 7 adjacent in the circumferential direction are formed around the axis X It has become.

  The pump casing 3 positioned at the lower end as a pump rises from the above-described suction port 4 that is circular in a vertical view, the flange-shaped mounting seat 11 formed around the downward suction port 4, and the mounting seat 11. A throttle case 12 having a curved cross-sectional shape so as to follow the tip shroud 8, a portion of the inner space of the pump casing 3 except for the impeller 2, that is, a fluid discharged from a plurality of discharge ports 2 b. It is configured in a spiral shape having a spiral chamber 10 that is stopped and guided to the discharge port 5 in the lateral direction. In the spiral pump, each discharge port 2b of the closed type impeller 2, that is, a fluid such as water discharged from the entire circumference is received by the spiral chamber 10 and is guided in the circumferential direction to flow quickly to the discharge port 5.

  According to the above-described configuration, when the main shaft 1 is driven and rotated by the prime mover 9 to drive the centrifugal pump P, fluid such as rainwater is sucked into the center of the impeller 2 from the suction port 4 by the rotation of the impeller 2, It rotates with the impeller 2 and is discharged from the entire circumference of the impeller 2 (that is, the discharge port 2 b) by centrifugal force. The discharged fluid is received and guided by the spiral chamber 10 and guided to the discharge port 5. It is discharged.

  As shown in FIGS. 1 and 2, a sliding portion S formed between the outer peripheral end 8 </ b> A of the tip shroud 8 and the upper end of the throttle case 12 in the pump casing 3 is provided. The sliding portion S includes an outer liner ring 13 fitted and fitted to the throttle case portion 12 and an inner liner ring 14 fitted and fitted to the outer peripheral end 8A, and the inner circumferential surface 13a and the inner side of the outer liner ring 13. The outer peripheral surface 14a of the liner ring 14 is arranged so as to face the outer ring 14a in an extremely close proximity. Both the inner and outer liner rings 14 and 13 have concentric cylindrical surfaces with the axis X as the center.

  At the upper end of the throttle case 12 (the lower end of the pump casing 3), a receiving wall 12a for preventing the outer liner ring 13 from coming down is formed. In addition, a circumferential notch 8b that prevents the inner liner ring 14 having a substantially L-shaped cross-section from being pulled upward is formed at the outer peripheral tip 8A of the tip shroud 8.

  Accordingly, mud and dust are sucked together with the drainage operation, so that mud and dust are inserted into the circumferential gap portion 15 (which is also the inner space portion of the pump casing 3) 15 between the tip shroud 8 and the throttle case portion 12. Even if a foreign substance such as enters, the circumferential gap portion 15 is an open space at the lower end and naturally falls off due to gravity. Therefore, even if it enters temporarily, it does not stay or accumulate. It will not occur. In the vertical shaft type pump of the first embodiment, since the sliding portion S is provided at the upper end of the circumferential gap portion 15, it is difficult for foreign matter to enter from the spiral chamber side. Since there is no choice but to move upward from the side, there is an advantage that foreign matter such as mud and dust is difficult to enter structurally.

[Example 2]
As shown in FIG. 3, the centrifugal pump according to the second embodiment is basically the same as the vertical shaft spiral pump according to the first embodiment shown in FIG. 1, and only the shape of the lower portion of the pump casing 3 is different. That is, the pump casing 3 includes a main body casing portion 3A having a spiral chamber 10 and a lower casing 3B attached to the annular bottom surface 3a. The lower casing 3B includes an annular flange portion 16 that is bolted to the main body case portion 3A, and a straight cylindrical suction case portion 17. The lower end of the suction case portion 17 forms a suction port 4 having a large diameter. is doing. The sliding portion S has the same structure as that shown in FIG. Further, the lower casing 3B may be configured such that the flange portion 16 and the suction case portion 17 are integrally formed, or may be configured such that the flange portion 16 and the suction case portion 17 are integrated by an integrating means such as a bolt.

  In the structure of the second embodiment, the circumferential gap portion 15 is a large space whose lower end is largely opened. Accordingly, it is difficult for mud and foreign matter to enter the circumferential gap portion 15 temporarily, and it is easy to be discharged downward as compared with the structure of the first embodiment. Problems with deposition have been wiped out. Further, in the centrifugal pump P of the second embodiment, even if it is used as a horizontal axis type pump whose axis X is oriented horizontally, even if foreign matter remains on the suction case part 17, it moves sideways and is discharged. Therefore, it is difficult for foreign matter to bite into sliding parts such as the sliding part S.

Example 3
As shown in FIG. 4, the centrifugal pump according to the third embodiment is basically the same structure as the vertical shaft type centrifugal pump of the first embodiment shown in FIG. 1, and only the lower part of the pump casing 3 is different. That is, the pump casing 3 has a configuration in which the lower casing 3B of the second embodiment shown in FIG. 3 is omitted, and is composed only of the main body case portion 3A that is a portion that supports the sliding portion S. Yes. Accordingly, the bottom surface 3a (same as the bottom surface 3a in FIG. 3) is the lowermost end as the casing. In this case, the suction port 4 is constituted by the impeller 2, specifically, the suction port 2 a of the tip shroud 8. The seal portion S is the same as that of the first and second embodiments, and is formed across the outer peripheral portion tip 8A of the tip shroud 8 and the lower end portion of the pump casing 3.

  In this case, since there is no portion covering the tip shroud 8 in the pump casing 3, there is a disadvantage that foreign matter such as mud and dust enters or accumulates in the circumferential gap portion 15 as shown in FIGS. A centrifugal pump that does not occur fundamentally.

  Next, a case where some other structures of the sliding portion are applied to the centrifugal pump having the structure shown in FIG. 4 as an example will be briefly described. As shown in FIG. 5, the sliding portion S of another structure 1 is provided with an outer liner ring 13 having an L-shaped cross section at the inner peripheral portion of the lower end of the pump casing 3, and the outer peripheral surface 8 a of the tip shroud 8 and the outer side. The inner ring surface 13a of the liner ring 13 is arranged so as to be opposed in close proximity.

  As shown in FIG. 6, the seal portion S of another structure No. 2 is provided with an outer liner ring 13 having a rectangular cross section at the inner peripheral portion of the lower end of the pump casing 3, and the outer peripheral surface 8 a of the tip shroud 8 and the outer liner ring 13. The inner peripheral surface 13a is arranged so as to be opposed in close proximity to each other. However, a circumferential retaining portion 18 that supports the outer liner ring 13 from below is formed at the lower end of the pump casing 3. As shown in FIG. 7, another structure No. 3 is obtained by forming a plurality of upper and lower circumferential grooves 19 on the inner peripheral surface 13 a of the outer liner ring 13 in the other structure 2 shown in FIG. 6. The circumferential groove 19 forms a sliding portion S having a labyrinth portion.

[Another Example]
The centrifugal pump shown in FIGS. 3 and 4 may be of a horizontal axis type in which the rotation axis X of the main shaft 1 is oriented horizontally and the spiral chamber axis Y is oriented vertically. When the centrifugal pump of FIG. 3 is a horizontal axis type, there is a possibility that foreign matter may enter the circumferential gap portion 15 from the suction port 4 side, but it opens greatly due to the pressure difference between the spiral chamber and the circumferential gap portion. It is easy to be discharged to the outside from the open end, so that it does not stay or accumulate, and therefore, the risk of damage due to biting of the invading foreign matter into the sliding portion is reduced. In addition, as shown in FIG. 4, in the centrifugal pump having a structure in which the portion covering the tip shroud in the pump casing is omitted, foreign matter does not stay in the same manner as in the case of the vertical shaft type. It is not to be. Furthermore, instead of the peripheral surface of the outer end of the tip shroud, the lower surface of the outer end may be used as the sliding portion.

As shown in FIGS. 8A and 8B, a tubular body having a suction port 2a that opens in the direction of the axis X and sucks fluid and a discharge port 2b that discharges in the direction transverse to the axis X. A centrifugal pump having an impeller (corresponding to claim 3) composed of the flow path 20 and a so-called non-clog impeller 2 is also possible. Even in this case, the sliding portion S is formed at the outer peripheral end of the tip shroud 8. One or a plurality of discharge ports 2b may be provided.

Sectional drawing (Example 1) which shows the structure of the principal part of a vertical axis | shaft spiral pump FIG. 1 is an enlarged sectional view showing a sliding portion in FIG. Sectional drawing which shows the structure of the principal part of a spiral pump (Example 2) Sectional drawing which shows the structure of the principal part of a spiral pump (Example 3) The expanded sectional view which shows the 1st another structure of the sliding part in FIG. The expanded sectional view which shows the 2nd another structure of the sliding part in FIG. FIG. 4 is an enlarged sectional view showing a third different structure of the sliding portion in FIG. A non-clog type impeller is shown, (a) is a longitudinal sectional view, (b) is a sectional view taken along line ZZ in (a).

Explanation of symbols

2 Impeller 2a Suction port 2b Discharge port
DESCRIPTION OF SYMBOLS 3 Pump casing 4 Suction port 5 Discharge port 6 Base end shroud 7 Blade 8 Tip shroud 8A Outer peripheral end 20 Tubular flow path A Centrifugal pump X Impeller rotational axis S Sliding portion

Claims (4)

A centrifugal pump having an impeller, a pump casing that rotatably accommodates the impeller, a fluid suction port, and a fluid discharge port formed in the pump casing;
The impeller is a centrifugal pump provided with a tip shroud formed at an inlet side end, and a sliding portion formed across an outer peripheral end of the tip shroud and the pump casing.   2. The centrifuge according to claim 1, wherein the impeller is formed with one or a plurality of blades arranged around an axis thereof, and a proximal shroud that connects and integrates the blades on the side opposite to the inlet side end. pump.   The centrifugal impeller according to claim 1, wherein the impeller includes a tubular flow path that is open in the axial direction and includes a suction port that sucks fluid and a discharge port that discharges in a lateral direction with respect to the axial center. pump.   The shaft center is vertically oriented so that the shaft center is vertically oriented, the suction port is formed downward at the lower end of the pump casing, and the discharge port is located laterally outside the pump casing. The centrifugal pump as described in any one of Claims 1-3 comprised by the vertical shaft type.

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