JP2007332890A - Resin submerged pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To capacitively increase displacement of a submerged pump, while improving portability, by reducing weight of the submerged pump. <P>SOLUTION: In this resin submerged pump 6, a rotary shaft 15 of a motor 18 is extended to one side, and an impeller 17 is installed in an extended part of this rotary shaft. The motor and the impeller are stored in casings 10, 11 and 13. A water suction port 20 is formed in an outer peripheral part of the casings. At the same time, the casings have a resin suction casing 11 forming a suction flow passage between the suction port and the impeller. A plurality of ribs 20 are arranged at an interval in the peripheral direction in the suction casing. An anti-suction side end part of these ribs extends up to a large diameter part from the smallest diameter part of an outer cylinder 11a of the suction casing of forming a wall surface opposed to the tip side of the impeller. A line formed of the anti-suction side end part of the ribs is formed at an obtuse angle to an average flow line of the suction flow passage or an average inclination of a suction port part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin submersible pump, and more particularly to a resin submersible pump suitable for being mounted on a drainage pump vehicle.

  An example of a conventional submersible pump used in a drainage pump vehicle is described in Patent Document 1. In the submersible pump described in this publication, in order to reduce the fluid loss in the pump casing and effectively cool the submersible motor, the suction port is formed in the outer peripheral portion over almost the entire circumference of the pump casing. Further, an impeller is disposed inside the pump casing. This impeller is attached to the protruding end of the shaft of the electric motor. In the pump suction port, the angle formed by the center of the flow line of the fluid flowing in the cross section including the shaft and the shaft on the motor side is set to 75 degrees or less.

  An example of a resin pump is described in Patent Document 2. The pump described in this publication is provided with a resin semi-open impeller, and a portion parallel to the main plate is formed on the blade open side so that a shape for obtaining a desired output can be easily confirmed.

JP 2001-115985 A JP-A-7-243398

  There are two types of drainage pump trucks: one that throws the submersible pump into the water by mechanical means such as a crane, and the other that throws it into the water with the help of humans. In the case of small and medium rivers, the latter is often used, and it is desired that a submersible pump can be easily put into a flooding river using only human hands. In the conventional submersible pump described in Patent Document 1, the pump efficiency is improved to reduce the weight. However, there is a limit to the weight reduction by improving the pump efficiency, and in order to increase the capacity of the submersible pump. There is a need for weight reduction by new methods.

  As a method for reducing the weight of the pump, it has been proposed to use a resin for the pump part. In Patent Document 2, the centrifugal impeller and the pump casing are made of synthetic resin. However, since the pump described in this publication is a stationary type, no consideration is given to the fact that the pump is portable and to be dropped in water, which is required for a submersible pump for drainage. In addition, if it is made of resin, it becomes possible to enlarge the pump, but in that case, it is not considered that the resin portion is sand eroded by sand contained in the water sucked into the resin portion. .

  The present invention has been made in view of the above problems of the prior art, and an object thereof is to reduce the weight of the submersible pump and improve the portability. Another object of the present invention is to increase the capacity of the submersible pump.

  A feature of the present invention that achieves the above object is that a rotating shaft of a motor extends to one side, an impeller is attached to an extended portion of the rotating shaft, and the motor and the impeller are accommodated in a casing. In the pump, a water suction port is formed in an outer peripheral portion of the casing, and the casing includes a suction casing that forms a suction flow path between the suction port and the impeller, a motor casing, and a discharge casing. A plurality of stationary blades are attached to the casing at intervals in the circumferential direction, and the suction casing, the discharge casing, and the stationary blades are made of resin, and the suction casing is provided with a plurality of ribs at intervals in the circumferential direction. The suction side end portion extends to a larger diameter portion than the minimum diameter portion of the outer cylinder of the suction casing that forms the wall surface facing the tip side of the impeller, and the anti-suction side end portion of the rib Formed to line, in which was formed to have an obtuse angle with respect to the average inclination of the suction opening of the mean streamlines or suction casing suction channel formed by the suction casing.

  In this feature, it is preferable to form a plurality of grooves at intervals in the circumferential direction from the suction side end of the impeller to the suction side of the inner surface of the outer casing of the suction casing. It is preferable to form a plurality of protrusions on the wall surface from the suction side end of the impeller to the suction side at intervals in the circumferential direction. Further, the groove or the protrusion may be extended in the axial direction, and the motor casing, the suction casing, and the discharge casing may be sequentially connected in the axial direction to form a cylindrical casing.

  According to the present invention, since the main part of the submersible pump is made of resin, the weight is reduced and the portability of the submersible pump is improved. In addition, according to the present invention, sand erosion due to the swirling back flow at the leading edge of the pump impeller is reduced, so that a high specific speed impeller can be used, and the amount of drainage can be increased.

  The significance of drainage pumps with excellent maneuverability has been recognized in order to quickly respond to river flooding caused by frequent heavy rains in recent years. Along with this, drainage pump vehicles have become widespread, and the total drainage volume of submersible pumps has increased. In the case of drainage by a drainage pump car, the pump car will be equipped with a set of facilities necessary for drainage including a submersible pump, and will be dispatched to the drainage site where flooding occurs due to river flooding. At the flood site, a submersible pump is thrown into the water to pump and drain the water.

  This will be described with reference to FIG. The drainage pump vehicle 7 is equipped with a submersible pump 6 and equipment necessary for drainage work. That is, the drain pump car 7 includes a power take-out device (PTO) 1 for taking out the power generated in the pump car 7, a generator 2 that generates power using the power taken out by the PTO 1, and a generator 2. Submersible pump 6 for draining with supplied electric power 6, inverter panel 4 for controlling the rotational speed of submersible pump 6 when driving submersible pump 6, operation panel 3 disposed between inverter panel 4 and generator 3, drain pump 6 And a drainage hose 5 for guiding the water discharged from the drainage to the drainage river.

  At the flood site, the drainage pump car 7 is driven to the shore. Then, the power of the drain pump car 7 is taken out via the PTO 1 and the generator 2 loaded on the drain pump car 7 is driven by the power obtained from the PTO 1. At this time, the electric power supplied from the generator 2 is supplied to the submersible pump 6 via the inverter panel 4. The submersible pump 6 and the inverter panel 4 are connected by an electric cable 8. At the same time, the drain hose 5 is connected to the submersible pump 6. When the submersible pump is dropped into the water, the flood water is drained to the river side through the drain hose 5.

  By the way, when draining from a flooding river using the submersible pump 6, the submersible pump 6 is operated on a system head curve determined from the difference in water level between the drainage destination river and the flooding river. However, until the discharge head of the submersible pump 6 overcomes the river revetment and forms a siphon, it operates on a system head curve different from the system head curve determined from the water level difference between the revetment and the flooding river. The

  In other words, in the operation determined from the difference in the water level between the revetment embankment and the flooding river that appears in the initial operation of the submersible pump 6, the submersible pump 6 is operated in a low flow area, so that it is relatively easy to form a siphon until now. A low specific speed pump with a small capacity and high head was used. When a high specific speed pump with a large capacity and a low head is used as the submersible pump, the low flow rate operation at the time of siphon formation at the beginning of the operation overlaps with the unstable region, and there is a possibility that a swirl backflow may occur from the leading edge of the impeller.

  The swirl backflow has a higher flow rate in the lower flow rate region, and in an extremely low flow rate operation near the deadline, the flow becomes as high as the peripheral speed of the center part of the impeller. Therefore, in the low flow rate region, sand erosion due to river water sediment occurs in the suction casing, and there is a risk that the resin-made part, particularly the root portion of the rib tip in the suction casing, where stress concentration is likely to occur, may be eroded. This problem is solved by the submersible pump according to the present invention described below.

  Several embodiments of the submersible pump according to the present invention will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional view of an embodiment of a resin submersible pump. The submersible pump 50 shown in the present embodiment is an outer peripheral suction and axial discharge type pump, and an impeller 17 is attached to an extending portion of the rotary shaft 15 constituting the rotor 18 b of the motor 18.

  In FIG. 1, the rotating shaft 15 of the motor 18 extends greatly to the right, and the bearings 16 a and 16 b rotatably support the intermediate portion and the left end side of the rotating shaft 15. A stator 18 a that forms the motor 18 together with the rotor 18 b is held in a cylindrical motor casing 13. The left end side surface of the motor casing is covered with an end cover 14 in which a bearing holding portion for holding the bearing 16b is formed. The end cover 14 is formed with a terminal for supplying electric power to the motor 18 and a terminal for transmitting various measurement signals of the pump.

  On the right side surface of the motor casing 13, a bearing housing 12 having a bearing holding portion for holding the bearing 16b is attached. A suction casing 11 having an outer diameter substantially the same as that of the bearing housing 12 and the motor casing 13 is attached to the right side surface of the bearing housing 12.

  The suction casing 11 has an inner cylinder 11b located on the left side in the figure and an outer cylinder 11a located on the right side in the figure, and a plurality of ribs arranged between the inner cylinder 11b and the outer cylinder 11a at intervals in the circumferential direction. 20 is connected. An opening (suction port) 24 is formed over the substantially entire outer periphery of the suction casing 11 to enable suction of the outer periphery. The outer periphery of the suction port 24 is covered with a strainer 22 to prevent dust and the like from entering the pump.

The axial center portion of the inner cylinder 11b has a cylindrical shape extending in the axial direction, and is fitted to the rotary shaft 15 with a gap. A portion between the attachment portion of the inner cylinder 11b to the bearing housing 12 and the shaft center portion has a trumpet shape so as to form a suction flow path. A mechanical seal 19 is attached to a portion of the rotating shaft 15 located on the back side of the inner cylinder 11b, and prevents water or the like from entering the motor 18 side. The outer cylinder 11a has a U-shaped vertical cross-sectional shape, the left part forms a suction channel with the inner cylinder 11b, and the right part forms the wall surface of the channel of the impeller 17 to be described in detail later. Form. Further, the right end portion is formed in a flange shape and engages with the flange portion of the outer cylinder 10a of the discharge casing 10 formed in a substantially cylindrical shape.

  The rotating shaft 15 of the motor 18 extends further leftward from the inner cylinder 11 b of the suction casing 11, and a diagonal flow impeller 17 is fitted into this extending portion and formed at the end of the rotating shaft 15. A nut is engaged and fixed to the bolt. The mixed flow impeller 17 is an open type impeller, and the outer cylinder 11a of the suction casing 11 forms a flow path wall surface as described above.

  An inner cylinder 10 b of the discharge casing 10 is disposed adjacent to the boss portion of the mixed flow impeller 17. The inner cylinder 10b of the discharge casing 10 has a cylindrical portion and a dome portion, and a plurality of stationary blades 21 are arranged at intervals in the circumferential direction on the outer periphery of the cylindrical portion. The outer diameter side of the stationary blade 21 is fixed to the inner surface of the outer cylinder 10 a of the discharge casing 10. A hose fitting 23 a for attaching a drainage hose is attached to the flange portion of the outer cylinder 10 a of the discharge casing 10, and a discharge port 25 is formed. A drainage hose 23c is attached to the hose attachment 23a via a hose fitting 23b.

  In the submersible pump 6 shown in this embodiment configured as described above, when the impeller 17 rotates, water is sucked into the submersible pump 6 obliquely as shown by an arrow 26 through the strainer 22 from the suction port 25. It is. Then, the pressure is increased by the impeller 17, moves to the right side as indicated by an arrow 27, and flows into the drainage hose 23 through the stationary blade 21 and the discharge casing 10.

  Here, the submersible pump 6 shown in the present embodiment is a so-called resin submersible pump, and the discharge casing 10, the suction casing 11, and the stationary blade 21 are made of resin. Thereby, the weight of the submersible pump 6 is reduced, and workability when the submersible pump 6 is thrown into the river is improved. Further, the impeller 17 is an impeller having a high specific speed of 1000 or more, which has a large amount of drainage, and the number of drain pumps necessary for draining from the river is reduced. Thereby, drainage preparation time is shortened, and quick drainage work becomes possible.

  As mentioned above, during drainage operation, the submersible pump 6 is operated on the system head curve determined by the difference in water level between the drainage destination river and the small and medium rivers. Until then, drive on the system head curve determined by the water level difference from the revetment. In this case, it is necessary to increase the total head, and the submersible pump 6 is operated in a low flow rate region.

  When the submersible pump 6 is operated near the point of use, the drainage is discharged from the suction port 24 through the impeller 17 along the meridional shape of the flow path and flows out to the outlet 25 side. On the other hand, when the submersible pump 6 is operated in a low flow rate region, a swirl reverse flow is generated from the front edge of the impeller 17. If the length of the rib 20 attached to the outer cylinder portion 11a of the suction casing 11 is long, the swirling backflow collides with the tip root portion of the rib 20, and the earth and sand contained in the drainage is removed from the root portion of the rib 20. May cause sand erosion.

  Therefore, in the submersible pump 6 of the present embodiment, the length of the rib 20 in the flow path direction is shorter than that of the conventional one. Specifically, the root position inner diameter Db, which is the connection position between the rib 20 and the inner wall surface of the outer cylinder 11a of the suction casing 11 and is closest to the impeller 17, is the minimum diameter of the inner wall surface of the outer cylinder 11a. De or higher. Furthermore, the angle α formed between the tip of the rib 20 on the side opposite to the suction port and the average streamline of the suction flow in the meridional section of the suction casing 11 is 90 degrees or more. Instead of the average streamline, the average inclination of the flow path in the vicinity of the suction port 24 in the meridian plane cross section can be used.

  FIG. 4 is a longitudinal sectional view showing the suction portion and the impeller portion of the submersible pump 6 shown in FIG. The flow indicated by the broken line A at the specification point changes as indicated by a two-dot chain line B in the low flow rate operation, and a backflow is generated from the front edge of the impeller 17. However, since the rib 20 attached to the outer cylinder part 11a of the suction casing 11 is substantially parallel to the swirling backflow, the collision angle of the swirling backflow is smaller than before. As a result, it is possible to prevent sand erosion that occurs at the root portion of the tip of the rib 20 attached to the outer cylinder portion 11a of the suction casing 11.

  Another embodiment of the submersible pump 6 according to the present invention is shown in a longitudinal sectional view centering on the impeller 17 in FIG. Unlike the submersible pump 6 of the above-described embodiment, the resin submersible pump 6 of the present embodiment is the inner wall surface of the outer cylinder 11a of the suction casing 11 and is near the inlet of the impeller 17 at a plurality of intervals in the circumferential direction. A groove 28 is formed. The groove 28 extends in the axial direction at a portion on the suction side that is the upstream side of the impeller 17.

  During the low flow range operation, it is possible to suppress the reverse flow speed generated from the leading edge of the impeller 17 and reduce the reverse flow speed, thereby reducing the collision angle. Therefore, it can suppress that the earth and sand contained in drainage carry out the sand erosion of the root part of the rib 20 attached to the outer cylinder part 11a of the suction casing 11, and also the durability with respect to sand erosion increases. In place of the groove 28 of the embodiment shown in FIG. 2, a plurality of protrusions 29 may be formed as shown in FIG. Also in this case, the projection 29 extends in the axial direction to the vicinity of the impeller 17. According to this example, the durability against sand erosion is further increased as in the embodiment shown in FIG.

It is a longitudinal cross-sectional view of one Example of the submersible pump which concerns on this invention. It is a principal part longitudinal cross-sectional view of the other Example of the submersible pump which concerns on this invention. It is a principal part longitudinal cross-sectional view of the modification of the submersible pump which concerns on this invention. It is a figure explaining the flow of a pump. It is a figure explaining the use condition of a drainage pump vehicle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... PTO, 2 ... Generator, 3 ... Operation panel, 4 ... Inverter panel, 5,23 ... Drain hose, 6 ... Submersible pump (drainage pump), 7 ... Drain pump car, 8 ... Electric cable, 9 ... Fuel conveyance Car: 10 ... Discharge casing, 10a ... Outer cylinder of discharge casing, 10b ... Inner cylinder of discharge casing, 11 ... Suction casing, 11a ... Outer cylinder of suction casing, 11b ... Inner cylinder of suction casing, 12 ... Bearing housing, 13 ... Motor casing, 14 ... End cover, 15 ... Rotating shaft, 16a, 16b ... Bearing, 17 ... Impeller, 18 ... Motor, 18a ... Stator,
18b ... rotor, 19 ... mechanical seal, 20 ... rib, 21 ... stationary blade, 22 ... strainer, 24 ... suction port, 25 ... discharge port, 26, 27 ... water flow, 28 ... groove, 29 ... projection, A ... flow at the specification point, B ... flow in the low flow operation area.

Claims (5)

In the resin submersible pump that extends the rotating shaft of the motor to one side, attaches the impeller to the extended portion of the rotating shaft, and houses the motor and the impeller in the casing,
A water suction port is formed on the outer periphery of the casing, and the casing includes a suction casing that forms a suction flow path between the suction port and the impeller, a motor casing, and a discharge casing. A plurality of stationary blades are attached at intervals in the circumferential direction, the suction casing, the discharge casing, and the stationary blades are made of resin, and a plurality of ribs are provided in the suction casing at intervals in the circumferential direction. The suction side end portion extends to a larger diameter portion than the minimum diameter portion of the outer cylinder of the suction casing forming a wall surface facing the tip side of the impeller, and a line formed by the anti-suction side end portion of the rib is formed. Made of resin, characterized in that it has an obtuse angle with respect to the average streamline of the suction flow path formed by the suction casing or the average inclination of the suction port of the suction casing Medium pump.   2. The resin according to claim 1, wherein a plurality of grooves are formed on the inner wall surface of the outer casing of the suction casing and spaced from each other on the suction side from the suction side end of the impeller in the circumferential direction. Submersible pump.   2. The resin according to claim 1, wherein a plurality of protrusions are formed on an inner wall surface of an outer cylinder of the suction casing and spaced from each other on the suction side of the impeller on the suction side. Submersible pump.   The resin submersible pump according to claim 2 or 3, wherein the groove or protrusion extends in the axial direction. 2. The resin submersible pump according to claim 1, wherein the motor casing, the suction casing, and the discharge casing are sequentially connected in the axial direction to form a cylindrical casing.

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