JP7214536B2 - underwater pump - Google Patents

Description

The technology disclosed herein relates to submersible pumps.

Patent Literature 1 discloses a submersible motor pump that is composed of a motor section and a pump section and that is immersed in pumped liquid. A motor portion of the submersible motor pump is formed with a circulation flow path for cooling water for cooling the motor. A lid casing is attached to the upper end of the pump casing which houses the impeller of the pump. The lid casing is a plate-like member that separates the motor section and the pump section. The lid casing also defines part of the circulation flow path.

JP 2012-57551 A

Due to the structure of the submersible motor pump, the plate-shaped lid casing also functions as a heat exchange section that exchanges heat between the cooling water and the pumped water. Fins are erected on the surface of the lid casing on the side of the pump section so as to increase the heat transfer area and improve the heat exchange efficiency. The fins make the surface of the lid casing on the side of the pump section uneven.

The surface of the lid casing on the side of the pump portion faces the back surface of the main plate of the impeller. If this surface has unevenness, there is a problem that the power for rotating the impeller increases.

In particular, if a back blade is provided on the back of the main plate of the impeller in order to reduce the shaft load, the back blade increases the shaft power, and the fins of the lid casing also increase the shaft power. As a result, there is a problem that the shaft power of the submersible pump is greatly increased.

The technology disclosed herein reduces power loss in submersible pumps.

The technology disclosed herein relates to submersible pumps. submersible pump,
an impeller fixed to the shaft of the motor and immersed in the pumping liquid;
a motor unit that houses the motor;
a partition facing the back surface of the main plate of the impeller and separating the inside of the motor unit from the pumped liquid;
The surface of the partition wall facing the main plate is an uneven surface configured by providing a plurality of at least one of concave and convex portions spaced apart in the circumferential direction ,
Between the partition wall and the main plate, a lid having smaller unevenness than the partition wall is interposed so as to face the uneven surface .

According to this configuration, at least one of concaves and convexes is provided on the surface of the partition facing the main plate of the impeller. The concavity and/or convexity increases the power to rotate the impeller.

In the above configuration, the lid is interposed between the partition wall and the main plate of the impeller. The lid faces the main plate of the impeller. The lid has less unevenness than the surface of the partition. Therefore, power loss during rotation of the impeller is reduced.

the motor unit includes a circulation flow path through which coolant for cooling the motor circulates,
The partition separates the cooling liquid and the pumping liquid, and constitutes a heat exchange section that transfers heat from the cooling liquid to the pumping liquid,
The lid may be provided with at least two passage holes through which the pumped liquid passes.

When the partition wall constitutes the heat exchange part, the recesses and/or protrusions provided on the partition wall increase the heat transfer area of the partition wall. The efficiency of heat exchange between the cooling liquid and the pumped liquid through the partition is improved. Since the partition wall can efficiently dissipate heat from the coolant, the motor can be efficiently cooled.

When the partition constitutes the heat exchange section, the liquid must be supplied to the surface of the partition on the side of the pump section. By providing at least two passage holes in the lid interposed between the partition wall and the impeller, when the impeller rotates, the pumped liquid flows through the passage holes from the pump section side to the partition wall side and passes through the passage holes. Through the hole, it flows from the partition wall side to the pump section side. Since the pumped liquid can be sequentially supplied to the partition wall, it is possible to improve the heat exchange efficiency between the cooling liquid and the pumped liquid via the partition wall.

As a result, both reduction in power loss and efficient cooling of the motor are achieved.

The partition wall has a constant or substantially constant thickness , and has a projection and a recess extending radially outward from a central portion of the partition wall at corresponding positions on the motor section side and the pump section side, respectively. A plurality of grooves may be formed in the circumferential direction so that the cross section along the axis of the shaft is wavy.

When the thickness of the partition wall is constant or substantially constant, the thermal conductivity increases, and when the cross section is made corrugated, the heat transfer area increases, so the heat exchange efficiency between the cooling liquid and the pumped liquid through the partition wall is improved. .

On the other hand, the partition wall has at least concaves or convexes on each of the motor section side and the pump section side. However, this submersible pump has a cover interposed between the partition wall and the impeller, as described above, so that power loss is reduced.

the septum and the lid each extend in a direction perpendicular to the axis of the shaft;
the shaft passes through a central portion of the partition wall and a central portion of the lid;
The passage holes may be provided in each of the radially inner portion and the radially outer portion of the inner portion.

Since the shaft passes through the central portion of the partition wall and the central portion of the lid, the pumped liquid flows in the radial direction while rotating in the circumferential direction between the partition wall and the main plate of the impeller. By providing passage holes in each of the radially inner portion and the radially outer portion of the lid, it is possible to smoothly flow the pumped liquid through the passage holes. The partition wall is advantageous in efficiently cooling the coolant.

The lid may be attached to the motor section. Alternatively, the lid may be attached to a pump casing that houses the impeller.

As described above, the submersible pump can reduce power loss.

FIG. 1 is a cross-sectional view illustrating the overall configuration of a submersible motor pump. FIG. 2 is an enlarged cross-sectional view illustrating the configuration of a housing portion between the motor portion and the pump portion. The left figure of FIG. 3 is a plan view of the partition, and the right figure is a bottom view of the partition and the lid. FIG. 4 is a sectional view along IV-IV in FIG. FIG. 5 is a diagram comparing characteristics of a submersible motor pump with a lid and without a lid. FIG. 6 is a diagram corresponding to FIG. 2 showing the configuration of a submersible motor pump having a partition different from that in FIG.

Embodiments of a submersible motor-pump will be described below with reference to the drawings. The submersible motor-pump described here is exemplary.

(Overall configuration of submersible motor pump)
FIG. 1 illustrates a submersible motor-pump 1 . The submersible motor pump 1 is, for example, a pump installed in a pump tank in a sewage system. The submersible motor pump 1 is immersed in the pumped liquid. The submersible motor-pump 1 includes a motor section 11 having a motor 31 for driving an impeller 21 and a pump section 12 having the impeller 21 . The submersible motor-pump 1 is arranged vertically so that the motor section 11 is on the upper side and the pump section 12 is on the lower side. The submersible motor pump 1 also has a forced cooling specification in which the motor portion 11 is provided with a circulation passage through which the circulating cooling liquid cools the motor 31, the details of which will be described later. Here, the cooling liquid is cooling water in which water is the main component in this configuration example, and an additive for corrosion prevention is added thereto. However, the coolant may be composed of cooling oil.

The motor section 11 includes a motor 31 and a motor casing 32 that houses the motor 31 . A shaft 33 of the motor 31 is arranged to extend in the vertical direction. The shaft 33 protrudes downward from the lower end of the motor casing 32 .

The motor casing 32 has a substantially cylindrical shape with its upper and lower ends opened. A top opening of the motor casing 32 is closed by a lid portion 34 . A bearing 351 is attached to the lower surface of the lid portion 34 , and this bearing 351 supports the upper end portion of the shaft 33 . A motor cover 39 is attached to the lid portion 34 , and a head cover 36 is attached to the motor cover 39 .

The motor section 11 also has an outer casing 37 . The outer casing 37 is arranged to surround the outer circumference of the motor casing 32 . The outer casing 37 has a substantially cylindrical shape with both ends opened, and its upper end is fixed to the motor cover 39 . The outer peripheral surface of the motor casing 32 and the inner peripheral surface of the outer casing 37 form a circular first flow path 38 through which the coolant flows. The first flow path 38 surrounds the motor 31 . The coolant flowing through the first flow path 38 receives heat from the motor 31 .

Lower ends of the motor casing 32 and the outer casing 37 are closed by the housing 4 . Details of the configuration of the housing 4 will be described later. The housing 4 forms part of the motor section 11 .

The pump section 12 includes an impeller 21 attached to the lower end of the shaft 33 and a pump casing 22 that houses the impeller 21 . This submersible motor pump 1 is a centrifugal pump provided with a centrifugal impeller 21 .

The pump casing 22 has a volute 23 in which the impeller 21 is housed. The volute 23 communicates with a suction port 24 opening at the bottom of the pump casing 22 . The volute 23 also communicates with a laterally projecting outlet 25 in the pump casing 22 . The discharge port 25 is connected to a discharge pipe (not shown).

The upper end of the pump casing 22 is open. A peripheral edge portion of the upper end opening of the pump casing 22 is fixed to the housing 4 .

The impeller 21 is not limited to the illustrated example, and various types of impellers can be adopted. A main plate 211 of the impeller 21 is provided with a rear blade 212 that reduces the axial load.

The housing 4 is arranged between the lower ends of the motor casing 32 and the outer casing 37 and the upper end of the pump casing 22 . The housing 4 includes a first member 41 and a second member 42, as also shown in FIG.

The first member 41 is fixed to the lower end of the motor casing 32 and the lower end of the outer casing 37 . The first member 41 has a substantially flat plate shape. The first member 41 closes the lower end opening of the motor casing 32 and the lower end opening of the outer casing 37 . A through hole through which the shaft 33 of the motor 31 passes is formed in the central portion of the first member 41 . A bearing 412 that supports the shaft 33 is held by the first member 41 . A plurality of communication holes 411 communicating with the first flow path 38 are formed in the outer peripheral portion of the first member 41 . 1 and 2, only one communication hole 411 is shown.

The second member 42 is arranged below the first member 41 . The second member 42 has a substantially cylindrical shape. The upper end of the second member 42 is fixed to the lower surface of the first member 41 . The lower end of the second member 42 is fixed to the upper end of the pump casing 22 .

The lower end of the second member 42 is open. A partition wall 6 is attached to the lower end of the second member 42 . The lower end of the second member 42 is closed by the partition wall 6 . The partition 6 also closes the top opening of the pump casing 22 . As will be described later, a lid 7 is interposed between the partition wall 6 and the main plate 211 of the impeller 21 .

A second flow path 421 and a third flow path 422 are formed inside the second member 42 . The second flow path 421 and the third flow path 422 are connected to the first flow path 38 through the communication holes 411 respectively. 1 and 2, the communication hole 411 that connects the second channel 421 and the first channel 38 is not shown. The first flow path 38, the second flow path 421, and the third flow path 422 constitute a circulation flow path through which the coolant circulates.

The partition wall 6 forms part of the third flow path 422 . The partition wall 6 separates the cooling liquid of the motor section 11 and the pumping liquid of the pump section 12 . The partition wall 6 also functions as a heat exchange section that exchanges heat between the cooling liquid and the pumped liquid.

The second flow path 421 and the third flow path 422 communicate with each other around the shaft 33 . That is, part of the circulation flow path is provided around the shaft 33 inside the housing 4 .

The housing 4 accommodates a mechanical seal 5 therein. The mechanical seal 5 seals the shaft 33 by being attached to the shaft 33 . The mechanical seal 5 is arranged at a communicating portion between the second flow path 421 and the third flow path 422 .

A circulation vane 51 is attached to the shaft 33 . The circulation vane 51 is arranged at a communicating portion between the second flow path 421 and the third flow path 422 . When the shaft 33 rotates, the circulation vanes 51 rotate together with the shaft 33 . When the circulation blades 51 rotate, the coolant is forced to flow from the second flow path 421 to the third flow path 422 along the shaft 33 . As a result, as indicated by thick black arrows in FIGS. and partition wall 6. The cooling liquid receives heat from the motor 31 around the motor 31 and radiates heat to the pumped liquid near the partition wall 6 .

(Structure of partition wall)
FIG. 3 shows partition 6 and lid 7 . The left figure of FIG. 3 is a plan view of the partition 6, and the right figure is a bottom view of the partition 6 and the lid 7. As shown in FIG. In other words, the left figure shows the surface of the partition wall 6 on the cooling liquid side, and the right figure shows the surfaces of the partition wall 6 and the lid 7 on the liquid side.

The partition wall 6 is disk-shaped and widens in a direction orthogonal to the shaft 33 . A through hole 61 through which the shaft 33 passes is formed in the central portion of the partition wall 6 . The partition 6 also has a corrugated cross section along the central axis of the shaft 33 in the circumferential direction of the partition 6, as shown in the cross-sectional view of FIG. A ridge 62 projecting from the pump section side to the motor section side is formed on the surface of the partition wall 6 facing the motor section, and the partition wall 6 has a protrusion 62 that protrudes from the pump section side toward the motor section side. A concave groove 63 is formed.

As described above, the partition wall 6 functions as a heat exchange section that exchanges heat between the cooling liquid and the pumped liquid. The heat transfer area of the partition wall 6 can be increased by making the cross section of the partition wall 6 wavy, thereby providing the partition wall 6 with the projection 62 on the motor side and the groove 63 on the pump side.

A plurality of ridges 62 are formed at intervals in the circumferential direction. Each of the plurality of ridges 62 extends radially outward from the edge of the through hole 61 in the partition wall 6 .

A rectifying path 64 for rectifying the cooling liquid is formed between adjacent ridges 62 . Here, as shown in FIG. 2, the projection 62 has a protruding end (that is, upper end) spaced from the wall of the housing 4 at a distance H. As shown in FIG. Since the gap H is relatively narrow, the flow of the coolant flows between the ridges 62 rather than the flow passing between the projecting ends of the ridges 62 and the wall of the housing 4 . Flow through rectifier path 64 becomes dominant. The projecting end of the ridge 62 may be brought into contact with the wall of the housing 4 so that the gap H is eliminated.

Each ridge 62 is curved in the circumferential direction from radially inward to outward. The curved direction of the ridges 62 coincides with the rotational direction of the shaft 33 indicated by the dashed line in FIG. As a result, the plurality of straightening paths 64 extend radially outward from the radially inner side, and each straightening path 64 is curved in the circumferential direction from the radially inner side to the outer side. there is The curving direction of the rectifying path 64 is the direction along the rotation direction of the shaft 33 . As shown in the left diagram of FIG. 3, each rectifying path 64 has a narrow radial inner width W1 and a wide radial outer width W2. The width of each rectifying path 64 gradually increases from the radially inner side toward the outer side.

As described above, the coolant flows along the shaft 33 near the shaft 33 at the mounting position of the mechanical seal 5 from the motor section side to the pump section side. Thereafter, the coolant flows radially inwardly outward along the surface of the partition wall 6 (see black arrows in FIG. 3). Since the cooling liquid flows radially along the surfaces of the partition walls 6 over the entire partition walls 6, the efficiency of heat exchange between the cooling liquid and the pumped liquid through the partition walls 6 is improved.

In addition, since the rectification path 64 is curved in the circumferential direction, the flow path length of the rectification path 64 can be made longer than in the case where the rectification path 64 is not curved. The heat transfer area of the partition wall 6 can be increased by increasing the length of the flow path. This configuration can increase the heat exchange efficiency of the partition wall 6 without increasing the outer diameter of the partition wall 6 .

Furthermore, as the width of the rectifying passage 64 gradually widens, the kinetic energy is converted into pressure energy by the diffuser effect while the coolant flows in the rectifying passage 64 radially outward from the central portion of the partition wall 6 . can be converted efficiently. With this configuration, the energy loss at the radially outward outlet of each rectifying path 64 can be reduced.

A concave groove 63 on the pump portion side of the partition wall 6 corresponds to the ridge 62 . Therefore, a plurality of grooves 63 are formed at intervals in the circumferential direction. Each of the plurality of grooves 63 extends radially outward from the edge of the through hole 61 in the partition wall 6 . Each groove 63 is curved in the circumferential direction from radially inward to outward. The pumped liquid flows radially along the concave grooves 63 .

The thickness of the partition wall 6 is constant or substantially constant as shown in FIG. Since the thickness of the wall separating the cooling liquid flowing along the straightening path 64 formed between the ridges 62 and the pumping liquid flowing inside the concave groove 63 is relatively thin, the cooling liquid and the pumping liquid are separated from each other. promotes heat exchange between The constant or substantially constant thickness of the partition walls 6 and the expansion of the heat transfer area combine to increase the heat exchange efficiency of the partition walls 6 . The partition wall 6 is made of cast iron, which has a relatively low thermal conductivity, from the viewpoint of durability and wear resistance. Even if the partition wall 6 is made of cast iron with low thermal conductivity, the partition wall 6 can efficiently cool the coolant. Moreover, since the cross section of the partition wall 6 is corrugated, the rigidity of the partition wall 6 can be ensured even if the thickness is reduced. If the thickness of the partition wall 6 is made as thin as possible, it is more advantageous for improving the heat exchange efficiency.

Here, as shown in FIG. 4, the corrugation of the partition wall 6 is inclined with respect to the central axis of the shaft 33 in a cross section along the central axis of the shaft 33 (see angle θ). As a result, the width of the groove 63 in the circumferential direction increases from the bottom toward the opening. That is, the width of the groove 63 in the circumferential direction increases from the upper end portion toward the lower end opening in FIG. Although not shown, the radial width of the groove 63 also increases from the bottom toward the opening. In the pump tank in which the submersible motor pump 1 is installed, the pumped liquid contains dust and the like, and the dust and the like may accumulate in the grooves 63 of the partition wall 6 having a corrugated cross section. If the partition wall 6 is formed so that the width of the groove 63 expands toward the opening, dirt and the like are easily scraped out of the groove 63 by the flow of pumped liquid during operation of the submersible motor pump 1 . It is possible to prevent dust and the like from accumulating in the concave groove 63 . It is possible to prevent the heat exchange efficiency of the partition wall 6 from deteriorating due to accumulation of dust and the like in the recessed groove 63 of the partition wall 6 . Here, the inclination angle θ of the waveform can be set to an appropriate angle. The tilt angle θ may be set within a range of 3 to 15°, for example.

Further, forming the corrugations so that the width of the grooves 63 of the partition walls 6 is widened can serve as a draft angle when the partition walls 6 are produced using a mold, which is advantageous from the standpoint of manufacturing the partition walls 6 as well. .

On the motor portion side of the partition wall 6, adjacent ridges 62 form a rectifying passage 64 for the cooling liquid, and on the pump portion side, a groove 63 forms a flow path for pumped liquid. be. These flow paths allow the cooling liquid to flow smoothly on both the motor section side and the pump section side with the partition wall interposed therebetween, thereby increasing the heat exchange efficiency of the partition wall 6 . The coolant can be efficiently cooled, and the motor 31 of the submersible motor pump 1 can be efficiently cooled.

Here, the surface of the partition wall 6 on the side of the pump section is the surface facing the main plate 211 of the impeller 21 . The concave grooves 63 formed on this surface form irregularities on the surface of the partition wall 6 on the side of the pump section. This unevenness increases the power for rotating the impeller 21 . In particular, since the main plate 211 of the impeller 21 is formed with the rear blades 212, the combination of the rear blades 212 and the grooves 63 may significantly increase the power loss of the submersible motor-pump 1. .

Therefore, the submersible motor pump 1 has the lid 7 interposed between the partition wall 6 and the main plate 211 of the impeller 21 . The lid 7 is an annular member that is thinner than the partition wall 6 . At least the surface of the lid 7 facing the main plate 211 of the impeller 21 is flat. The surface of the lid 7 is less uneven than the surface of the partition wall 6 on the pump section side. The lid 7 covers the entire surface of the partition wall 6 on the side of the pump section. Note that the illustration on the right side of FIG. 3 omits part of the lid 7 . A lid 7 is attached to the partition wall 6 . As shown in FIG. 4, a predetermined gap is provided between the lid 7 and the surface of the partition wall 6 on the side of the pump section.

Since the surface of the lid 7 facing the main plate 211 of the impeller 21 is flat, power loss during rotation of the impeller 21 is reduced.

Here, the partition wall 6 is a member that exchanges heat between the cooling liquid and the pumped liquid as described above. If the entire surface of the partition wall 6 is covered with the lid 7, the pumped liquid cannot be supplied to the surface of the partition wall 6 on the side of the pump section. Therefore, through holes 71 and 72 are formed in the lid 7 as shown in the right diagram of FIG. The passage holes 71 and 72 respectively penetrate the lid 7 in the thickness direction and connect the partition wall 6 side with the lid 7 therebetween and the main plate 211 side of the impeller 21 . A plurality of passage holes 71 and 72 are provided in the circumferential direction. The through holes 71 and 72 are evenly arranged in the circumferential direction, although only part of them are shown in FIG. The through hole 71 is provided radially inward. The through hole 72 is provided radially outward.

Between the partition wall 6 and the main plate 211 of the impeller 21, the pumped liquid flows in the radial direction while rotating in the circumferential direction. As indicated by solid arrows in FIG. 2, when the impeller 21 rotates, the pumped liquid flows from the pump section side to the partition wall side through the radially outward passage holes 72, It flows from the partition wall side to the pump portion side through the passage hole 71 . Since the pumped liquid can be sequentially supplied to the partition wall 6 by providing the through holes 71 and 72 on the radially inner side and the outer side, respectively, the heat exchange efficiency between the cooling liquid and the pumped liquid via the partition wall 6 is improved. can be improved.

That is, by interposing the lid 7 between the partition wall 6 and the main plate 211 of the impeller 21 and providing passage holes 71 and 72 in the lid 7, the power loss of the submersible motor pump 1 can be reduced and the motor 31 can be It is compatible with efficient cooling.

FIG. 5 is a diagram comparing the shaft power and the total lift when the lid is attached and when the lid is not attached. The upper diagram in FIG. 5 shows the relationship between the flow rate (horizontal axis) and the shaft power (vertical axis). The flow rate increases toward the right of the figure. The shaft power increases as you move up the figure. The lower diagram of FIG. 5 shows the relationship between the flow rate (horizontal axis) and the total head (vertical axis). The flow rate increases toward the right of the figure. The total head increases as you move up the figure.

As can be seen from FIG. 5, by attaching the lid 7, the shaft power is lower and the total lift is higher in all flow ranges than when the lid 7 is not attached. From FIG. 5, it can be confirmed that a large power reduction effect obtained by attaching the lid 7 can be obtained.

The submersible motor-pump 1 disclosed herein is not limited to the structure shown in FIGS. For example, FIG. 6 shows a modification of the submersible motor-pump 10 . In this submersible motor pump 10, the partition wall 60 is configured in a flat plate shape instead of a wavy cross section. The partition wall 60 has fins 601 projecting toward the pump section. Thereby, the partition wall 60 is intended to expand the heat transfer area. On the other hand, the surface of the partition wall 60 on the side of the pump section has unevenness due to the fins 601 .

For the partition wall 60 having this configuration as well, by interposing the lid 7 between the partition wall 60 and the main plate 211 of the impeller 21, power loss can be reduced in the same manner as described above.

Although illustration is omitted, the partitions 6 and 60 may be attached to the pump casing 22 .

Moreover, each configuration described above may be combined with each other within a possible range.

Further, motor pumps to which the technology disclosed herein can be applied are not limited to the motor pumps illustrated in FIGS. The technology disclosed herein can be applied to motor pumps with various configurations.

For example, the unevenness on the surface of the partition facing the main plate of the impeller is not limited to the unevenness for the purpose of increasing the heat transfer area described above.

Reference Signs List 1, 10 submersible motor pump 11 motor section 21 impeller 211 main plate 31 motor 33 shaft 38 first flow path (circulation flow path)
421 second channel (circulation channel)
422 third channel (circulation channel)
6 partition 60 partition 7 lids 71, 72 passage hole

Claims (6)

an impeller fixed to the shaft of the motor and immersed in the pumping liquid;
a motor unit that houses the motor;
a partition facing the back surface of the main plate of the impeller and separating the inside of the motor unit from the pumped liquid;
The surface of the partition wall facing the main plate is an uneven surface configured by providing a plurality of at least one of concave and convex portions spaced apart in the circumferential direction ,
A submersible pump , wherein a lid having unevenness smaller than that of the partition is interposed between the partition and the main plate so as to face the uneven surface .
The submersible pump according to claim 1,
the motor unit includes a circulation flow path through which coolant for cooling the motor circulates,
The partition separates the cooling liquid and the pumping liquid, and constitutes a heat exchange section that transfers heat from the cooling liquid to the pumping liquid,
The submersible pump, wherein the lid is provided with at least two passage holes through which the pumped liquid passes. The submersible pump according to claim 2,
The partition wall has a constant or substantially constant thickness , and has a projection and a recess extending radially outward from a central portion of the partition wall at corresponding positions on the motor section side and the pump section side, respectively. A submersible pump in which a plurality of grooves are formed in a circumferential direction so that a cross section along the axis of the shaft is wavy. The submersible pump according to claim 2 or 3,
the septum and the lid each extend in a direction perpendicular to the axis of the shaft;
the shaft passes through a central portion of the partition wall and a central portion of the lid;
The submersible pump, wherein the passage holes are provided in each of a radially inner portion and a radially outer portion of the inner portion. In the submersible pump according to any one of claims 1 to 4,
The submersible pump, wherein the lid is attached to the motor section. In the submersible pump according to any one of claims 1 to 4,
The submersible pump, wherein the lid is attached to a pump casing that houses the impeller.

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