Pump

Abstract

This pump comprises a casing and an impeller that comprises a first shroud (720) that covers vane parts (710). The casing has a groove part (312) into which the tip (722a) of a suction port mouth part (722) of the first shroud (720) is inserted and an inside wall part (313) that is further toward the inner circumferential side than the groove part (312). A return passage (360) that has a labyrinth structure (361) that is formed by the suction port mouth part (722) and the groove part (312) on the inner circumferential side is formed between the casing and the first shroud (720). The first shroud (720) has an extending part (726) that has an opposing surface (726a) that is opposite an end surface (313a) of the inside wall part (313) that is on the vane part (710) side in the axial direction.

Description

Pump

[0001] The present disclosure relates to a pump.

[0002] Conventionally, a pump is known that includes a casing having a suction passage formed with a suction port for sucking a liquid and a discharge passage formed with a discharge port for discharging the sucked liquid, and an impeller having a suction port mouth portion communicating with the suction passage, which is housed in the casing and rotates about an axis.

[0003] In such a pump, generally, a return path is formed between the casing and the impeller that circulates from the outer peripheral side of the impeller into the suction port mouth portion. However, since the flow of the liquid into the return path has nothing to do with the original pump action, if a large amount of liquid flows into the return path, the pump efficiency decreases.

[0004] Therefore, it has been proposed to provide a labyrinth structure formed by the suction port mouth portion and the groove portion in the return path by forming a groove portion in the casing into which the tip of the suction port mouth portion is inserted. By providing the labyrinth structure in the return path in this way, the flow path resistance in the return path can be increased. Therefore, the flow of the liquid into the return path is suppressed, and it becomes possible to suppress the decrease in the pump efficiency.

[0005] However, when a labyrinth structure is provided on the inner peripheral side of the return path by forming a groove portion in the casing into which the tip of the suction port mouth portion is inserted, the wall portion of the casing exists on the inner peripheral side of the suction port mouth portion. Therefore, a step is formed on the downstream side where the diameter significantly expands between the suction port mouth portion and the wall portion of the casing.

[0006] When such a step is formed, the flow of the main path of the pump from the suction port side may be disturbed, and the pump efficiency may decrease. In addition, since the main path of the pump rapidly expands at this step, a pressure drop occurs in the vicinity of the step, which promotes the flow of the return path. As a result, the pump efficiency may also decrease.

[0007] Therefore, Patent Document 1 below proposes that by interposing a sliding member between the intake mouth portion and the casing to shield the return path, the flow in the return path can be suppressed even when the pressure drops near a step.

[0008] Japanese Patent Publication No. 2008-240655

[0009] The configuration disclosed in Patent Document 1 above can also suppress the decrease in pump efficiency. However, it is preferable to also suppress the generation of sliding losses, noise, and vibration.

[0010] Therefore, the present disclosure aims to provide a pump that can suppress the decrease in pump efficiency while suppressing the generation of sliding loss, noise, and vibration.

[0011] A pump according to one aspect of the present disclosure comprises a casing having an intake passage formed with an intake port for drawing in liquid and a discharge passage formed with an outlet for discharging the drawn-in liquid, and an impeller housed in the casing and rotating about an axis. The impeller comprises a blade portion that accelerates the liquid by rotational centrifugal force and a first shroud covering the side of the blade portion facing the intake passage. The first shroud comprises a shroud body portion on which a plurality of the blade portions are connected in series, and an intake port mouth portion connected to the inner circumference side of the shroud body portion and communicating with the intake passage. The casing has a groove portion into which the tip of the intake port mouth portion is inserted, and an inner wall portion located on the inner circumference side of the groove portion. A return path is formed between the casing and the first shroud, which allows fluid to circulate from the outer circumference side of the impeller into the intake port mouth portion. The return path has a labyrinth structure on its inner circumference formed by the intake mouth portion and the groove portion. The first shroud has an extended portion formed thereon that faces the end face on the wing portion side in the axial direction of the inner wall portion.

[0012] According to this disclosure, it is possible to obtain a pump that can suppress the decrease in pump efficiency while suppressing the generation of sliding loss, noise, and vibration.

[0013] Figure 1 is a plan view showing an example of a pump according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view showing an example of a pump according to this embodiment. Figure 3 is a perspective view of the first shroud and blades of an example of a pump according to this embodiment, viewed from one side. Figure 4 is a perspective view of the first shroud and blades of an example of a pump according to this embodiment, viewed from the other side. Figure 5 is a rear view showing the first shroud and blades of an example of a pump according to this embodiment. Figure 6 is a rear view showing the first shroud and blades of an example of a pump according to this embodiment. Figure 7 is a rear view showing the casing of an example of a pump according to this embodiment. Figure 8 is a partially enlarged view of Figure 2.

[0014] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted.

[0015] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0016] In the following explanation, the direction of rotation of the impeller is defined as the front-to-back direction, and the intake side in that direction is defined as the front side.

[0017] (Embodiment) As shown in Figures 1 and 2, the pump 1 according to this embodiment comprises a pump body 10 that constitutes the outer casing, and a rotating body 20 housed in a rotating body housing chamber 510 formed inside the pump body 10.

[0018] The pump body 10 consists of a casing 30 with a pump chamber 330 that opens to the rear and a drive block 40 with a storage section 450 that opens to the front (see Figure 2).

[0019] The housing section 450 of the drive block 40 is connected to the pump chamber 330 of the casing 30, and the housing section 450 and the pump chamber 330 together form a rotating body housing chamber 510 that houses the entire rotating body 20.

[0020] As shown in Figure 2, the drive block 40 includes a separation wall 410, a magnetic drive unit 460, a control unit 470, and a molded resin 480 forming the outer casing.

[0021] The separation wall 410 is made of synthetic resin and can be formed from, for example, polyphenylene sulfide (PPS) resin.

[0022] The separation wall 410 is formed in the shape of a bottomed cylindrical container that opens forward. The separation wall 410 consists of a bottom portion 420, a peripheral wall portion 430 extending forward from the outer circumference of the bottom portion 420, and a flange portion 440 projecting radially outward from the front edge of the peripheral wall portion 430. In this embodiment, the flange portion 440 is formed over the entire circumference of the peripheral wall portion 430.

[0023] The bottom portion 420 and the peripheral wall portion 430 define a storage compartment 450 in which the front is open and the rear is closed by the bottom portion 420.

[0024] Thus, in this embodiment, a housing 50 is constructed in which a rotating body storage chamber 510 for housing the rotating body 20 is formed by the casing 30 and the separation wall 410.

[0025] A cylindrical rib 421 (rear shaft fixing part: shaft support part) that protrudes forward is formed in the center of the bottom 420 of the storage section 450 (the center of the back of the storage section 450). The rear end of the shaft 60 (rotating shaft) that rotatably supports the rotating body 20 is inserted into the rib 421. The shaft 60 can be made of, for example, ceramics.

[0026] The shaft 60 is held immobilely by the separation wall 410. Such a configuration can be formed, for example, by shaping the contour of the rear end of the shaft 60 into a D shape and providing a D-shaped portion corresponding to the rear end of the shaft 60 inside the cylindrical rib 421.

[0027] In this embodiment, a stator, which serves as a magnetic drive unit 460, is arranged on the outer circumference of the peripheral wall portion 430. By driving the magnetic drive unit 460, a magnetic field is generated that rotates the magnetically driven portion 80 of the rotating body 20, which will be described later. For this reason, the separation wall 410 can also be formed using a metal that does not affect the magnetic drive.

[0028] The rotating body 20 has an impeller 70 as a pump section located at its front and a magnetic drive section 80 located at the rear of the impeller 70. In this embodiment, the impeller 70 and the magnetic drive section 80 are connected via a neck section 90, which is a connecting section (see Figure 2). In this embodiment, the impeller 70, the magnetic drive section 80, and the neck section 90 are integrally formed. That is, the impeller 70 is integrally provided at the front of the magnetic drive section 80 (one end in the direction of the shaft 60).

[0029] The magnetically driven part 80 of the rotating body 20 is housed in the housing part 450, and the impeller 70 is housed in the pump chamber 330. In this embodiment, the pump chamber 330 consists of a circular impeller housing chamber 340 in plan view that houses the impeller 70, and a volute part 350 in plan view that is formed on the outer circumference of the impeller housing chamber 340 and provides a pressure-increasing effect to the liquid.

[0030] The magnetically driven unit 80 is housed in the housing unit 450 and is a rotor that is rotatably supported by the shaft 60.

[0031] The magnetically driven unit 80 consists of a fixed member 810 made of synthetic resin, a magnet unit 820 fixed to the outer circumference of the fixed member 810, and a bearing 830 fixed to the inner circumference of the fixed member 810. The fixed member 810 can be formed using, for example, polyphenylene ether (PPE) resin. The magnet unit 820 can be formed using a permanent magnet such as ferrite or samarium iron (SmFe). The bearing 830 can be formed using a carbon-containing resin sliding material or ceramics.

[0032] In this embodiment, the fixing member 810 is formed integrally with the neck portion 90 and the rear shroud 730, as shown in Figure 2.

[0033] The magnet section 820 is formed of a magnet body 821 and a stainless steel or resin magnet cover 822 that covers the outer surface of the magnet body 821. Alternatively, the magnet cover 822 may be omitted, so that the outer surface of the magnet body 821 is exposed on the outer circumference of the magnetically driven section 80 (rotor). A through hole 831 is formed in the center of the bearing 830, and the rotating body 20 is rotatably supported by inserting the shaft 60 through the through hole 831.

[0034] The magnetically driven unit 80 is arranged such that the magnet portion 820 faces the magnetically driven unit 460 via the peripheral wall portion 430 of the separation wall 410. A gap d1 is formed between the magnet portion 820 and the peripheral wall portion 430 to allow rotation of the magnetically driven unit 80.

[0035] The impeller 70, which functions as a pump located in front of the magnetically driven unit 80, is equipped with multiple blades 710 arranged at approximately equal intervals in the circumferential direction of the impeller 70, which accelerate the liquid by rotational centrifugal force. Furthermore, the impeller 70 is equipped with a front shroud 720 that covers the front side (one side in the axial direction) of the blades 710 and a rear shroud 730 that covers the rear side (the other side in the axial direction) of the blades 710. The front shroud 720 corresponds to a first shroud, and the rear shroud 730 corresponds to a second shroud.

[0036] In this embodiment, the front shroud 720 is composed of a front shroud body portion 721 that tapers in diameter towards the front and has multiple vane portions 710 connected to its front ends, and a cylindrical portion 722 whose rear end 722b is connected to the front end of the front shroud body portion 721 and which is formed to protrude forward. The front shroud body portion 721 corresponds to the shroud body portion, and the cylindrical portion 722 corresponds to the intake mouth portion. The front end of the front shroud body portion 721 is the inner circumference end portion 723.

[0037] On the other hand, the rear shroud 730 is formed in a substantially disc shape, and a through hole 730a is formed in the central part of the rear shroud 730. The fixing member 810 is connected to the peripheral edge of the through hole 730a of the rear shroud 730, that is, the inner circumferential end 731 of the rear shroud 730, via a neck portion 90. In other words, the neck portion 90 corresponds to the connection portion. In this embodiment, the front surface 733 of the rear shroud 730 is a flat surface extending in the radial direction. The front surface 733 of the rear shroud 730 is the inner surface on the second shroud side of the centrifugal flow path 760, which will be described later.

[0038] In this embodiment, the rear shroud 730 and the magnetically driven portion 80 are formed by insert molding. Specifically, with the magnet portion 820 and the bearing 830 inserted into a mold (not shown), resin is filled into the mold to form the rear shroud 730, the neck portion 90, and the fixing member 810. In this way, the rear shroud 730 and the magnetically driven portion 80 are formed as a single unit.

[0039] Each of the blades 710 is roughly plate-shaped and is integrally mounted on the rear surface 725 of the front shroud body 721 with its plate thickness intersecting the axial direction (see Figures 3 to 6). The rear surface 725 of the front shroud body 721 is the inner surface of the first shroud side of the centrifugal flow path 760, which will be described later. In this embodiment, each of the blades 710 is formed in a gentle arc shape with the front side in the direction of rotation being convex.

[0040] Each of the wing portions 710 is provided in the range from the inner circumferential end portion 723 of the front shroud body portion 721 to the outer circumferential end portion 724 of the front shroud body portion 721.

[0041] On the other hand, the rear end of each of the wing portions 710 is attached to the front surface 733 of the rear shroud 730, and each of the wing portions 710 is provided in the range from the inner circumferential end 731 of the rear shroud 730 to the outer circumferential end 732 of the rear shroud 730.

[0042] Between the front shroud main body 721 and the rear shroud 730, there are formed in the circumferential direction a plurality of space portions defined by two adjacent blades 710, the front shroud 720, and the rear shroud 730, with openings on the radially inner side and the radially outer side. Each of the plurality of space portions forms a centrifugal flow path 760 that is a part of the impeller flow path 740 formed within the impeller 70. Each of the centrifugal flow paths 760 has an inlet 761 at the radially inner opening and an outlet 762 at the radially outer opening.

[0043] In the present embodiment, an introduction path 750 that is a part of the impeller flow path 740 is formed on the radially inner side of the centrifugal flow path 760.

[0044] The introduction path 750 is formed to extend in the axial direction from the front end 722a (tip) side of the cylindrical portion 722 to the through hole 730a of the rear shroud 730. Each inlet 761 of the centrifugal flow path 760 communicates with the introduction path 750.

[0045] When the impeller 70 having such a configuration is rotated, the liquid introduced into the centrifugal flow path 760 from the introduction path 750 through the inlet 761 is accelerated by the centrifugal force of the rotating impeller 70 and discharged radially outward from the outlet 762.

[0046] The liquid discharged from the outlet 762 to the outer peripheral side of the impeller 70 is introduced into the volute portion 350 and pressurized in the volute portion 350.

[0047] The casing 30 is made of a synthetic resin and can be formed, for example, of polyphenylene sulfide (PPS) resin. It is also possible to make the casing 30 of metal.

[0048] The casing 30 includes a top wall 310 and a peripheral wall 320 that projects rearward from the periphery of the top wall 310, and is formed in a container shape that opens rearward. The pump chamber 330 described above is defined by the inner surface 311 of the top wall 310 and the inner surface 321 of the peripheral wall 320.

[0049] In this embodiment, the peripheral wall 320 of the casing 30 is located outside the peripheral wall portion 430 of the separation wall 410, and the outer periphery of the pump chamber 330 bulges radially outward from the housing portion 450. The outer periphery of the impeller 70, which protrudes radially outward from the magnetically driven portion 80, is positioned in this bulging portion. The impeller 70 is positioned so that the rear surface of its outer periphery faces the front surface of the inner periphery of the flange portion 440. This rear surface of the outer periphery is the rear surface on the outer periphery side of the rear shroud 730.

[0050] In this embodiment, the rear surface of the peripheral wall 320 is brought into contact with the outer circumference of the front surface of the flange portion 440, thereby connecting the storage portion 450 and the pump chamber 330 of the casing 30.

[0051] The casing 30 is attached to the separation wall 410 by a plurality of screws 130. Specifically, the casing 30 is fixed to the separation wall 410 by inserting the screws 130 from the front while the peripheral wall 320 of the casing 30 is in contact with the flange portion 440 of the separation wall 410. A sealing material 100 such as a packing is interposed at the joint between the casing 30 and the flange portion 440 to ensure the watertightness of the rotating body housing chamber 510.

[0052] A suction pipe 380 connected to the upstream piping is formed in the center of the top wall 310 of the casing 30, and a suction passage 381 for introducing liquid into the pump chamber 330 is formed inside the suction pipe 380. On the other hand, a discharge pipe 390 connected to the downstream piping is formed in the peripheral wall 320 of the casing 30, and a discharge passage 391 for discharging the liquid in the pump chamber 330 to the outside (connected piping, etc.) is formed inside the discharge pipe 390.

[0053] The suction pipe 380 is projected forward from the center of the top wall 310, and an inlet 381a is formed at the tip of the suction pipe 380, which opens forward to draw liquid into the suction passage 381. The suction passage 381 communicates with the flow path of the upstream piping connected to the suction pipe 380 via the inlet 381a formed on the upstream side. Specifically, the suction pipe 380 and the upstream piping are connected by fixing them with a fixing member such as a quick fastener while the flange portion 380b formed at the tip of the suction pipe 380 and the flange portion formed at the tip of the upstream piping are abutted together.

[0054] In this embodiment, with the impeller 70 positioned in the pump chamber 330, the suction passage 381 communicates with the introduction passage 750 of the impeller passage 740.

[0055] Specifically, the rear end 380a of the suction pipe 380 protrudes into the pump chamber 330, and an outlet 381b that opens to the rear is formed at the protruding rear end 380a. By inserting the outlet 381b of the rear end 380a into the inlet passage 750, the suction passage 381 is connected to the inlet passage 750. The outlet 381b of the suction passage 381 also serves as the inlet for the inlet passage 750.

[0056] In this embodiment, an annular groove 312 is formed on the outer circumference of the rear end portion 380a that protrudes into the pump chamber 330, and the rotation of the impeller 70 is guided by inserting the front end portion 722a of the cylindrical portion 722 into the groove 312.

[0057] In this embodiment, both the intake passage 381 and the introduction passage 750 are arranged to extend in the front-rear direction. Therefore, the liquid in the intake passage 381 and the liquid in the introduction passage 750 flow mainly from the front to the rear in the axial direction. That is, the suction passage 381 and the introduction passage 750 have the axial front side as the upstream side and the axial rear side as the downstream side.

[0058] On the other hand, the discharge pipe 390 is provided to protrude outward from the side of the peripheral wall 320, and a discharge port 391b is formed at the tip of the discharge pipe 390 that opens outward and discharges liquid to the outside from the discharge passage 391 (see Figure 7). The discharge passage 391 communicates with the flow path of the downstream piping connected to the discharge pipe 390 via the discharge port 391b formed on the downstream side. Specifically, the discharge pipe 390 and the downstream piping are connected by fixing them with a fixing member such as a quick fastener while the flange portion 390a formed at the tip of the discharge pipe 390 and the flange portion formed at the tip of the downstream piping are abutted together.

[0059] The discharge passage 391 has an inlet 391a formed on its upstream side and is connected to the end point 350b of the volute section 350 via the inlet 391a. The discharge port 391b opens in a direction intersecting the axial direction (in this embodiment, a perpendicular direction).

[0060] In this embodiment, the discharge passage 391 is formed to extend tangentially near the endpoint 350b of the spirally formed volute section 350. That is, the liquid in the discharge passage 391 flows mainly tangentially near the endpoint 350b of the volute section 350.

[0061] In this way, by extending the discharge passage 391, which communicates with the endpoint 350b of the volute section 350, in the tangential direction near the endpoint 350b of the volute section 350, a tongue portion 324 is formed on the peripheral wall 320 of the casing 30 near the endpoint 350b of the volute section 350. The tongue portion 324 branches the volute section 350 and the discharge passage 391, and the starting point 350a of the volute section 350 is formed between the tip of the tongue portion 324 and the outer circumference of the impeller 70.

[0062] The casing 30 is provided with a front shaft fixing portion 370 (shaft support portion) located in the center of the rotating body storage chamber 510, and the front end of the shaft 60 is fixed to the rear of the front shaft fixing portion 370.

[0063] As described above, the shaft 60 is held immobilely by the separation wall 410, and the casing 30 and the separation wall 410 are fixed together by screws 130. Therefore, the relative rotation of the shaft 60 with respect to the casing 30 can be restricted even without immobilizing the front end of the shaft 60 by the casing 30. Thus, it is not necessary to immobilize the front end of the shaft 60 by the casing 30. However, it is also possible to immobilize the front end of the shaft 60 by the casing 30.

[0064] In this embodiment, the front shaft fixing portion 370 is integrally formed with the casing 30 via a plurality of support ribs 373 extending from the inner surface of the suction pipe 380 toward the pump chamber 330. The front shaft fixing portion 370 consists of a cone-shaped projection 371 that protrudes toward the front and a cylindrical bearing portion 372 connected to the rear of the projection 371 to support the front end of the shaft 60.

[0065] In Figure 2, the bearing plate 110 receives the thrust load applied to the bearing 830. The bearing plate 110 is positioned on both the front and rear sides of the bearing 830, and when the magnetic drive unit 80 is rotated, it suppresses wear on the parts of the casing 30 that face the magnetic drive unit 80 (the rear end of the cylindrical bearing portion 372 and the front end of the rib 421).

[0066] In this embodiment, the cone-shaped projection 371 is positioned within the inlet passage 750 of the impeller flow path 740 with the impeller 70 located in the pump chamber 330. The projection 371 has a tapered tip that faces upstream, and the flow path of the liquid introduced into the inlet passage 750 is altered by the projection 371.

[0067] Thus, the protrusion 371 has the function of changing the direction of liquid flow, and in this embodiment, the protrusion 371 corresponds to the flow direction changing part.

[0068] In this embodiment, the impeller flow path 740 is formed to discharge liquid flowing in from the axial front toward the radially outward direction.

[0069] In other words, the direction in which the liquid primarily flows when introduced into the introduction passage 750 (axial direction) and the direction in which the liquid primarily flows when discharged from the discharge port 762 of the centrifugal passage 760 (radial direction) intersect.

[0070] Therefore, in this embodiment, a protruding portion 371 is placed in the introduction passage 750 as a flow direction changing portion, and the protruding portion 371 changes the flow direction of the liquid flowing axially to be closer to the radial direction. In this way, the liquid can be introduced more smoothly from the introduction port 761 into the centrifugal passage 760.

[0071] The pump 1, configured in this way, is driven by the control unit 470 energizing the magnetic drive unit 460. Specifically, by energizing the magnetic drive unit 460 and generating a magnetic field in the magnetic drive unit 460, the magnet portion 820 of the rotating body 20 is attracted to and repelled by the magnetic drive unit 460, causing the magnetic driven portion 80 to rotate around the shaft 60. As a result, the impeller 70 rotates around the shaft 60 which extends in the front and rear directions.

[0072] As the impeller 70 rotates, the liquid introduced into the impeller flow path 740 from the intake port 381a via the intake passage 381 is discharged from the discharge port 762 to the outer circumference of the impeller 70. The liquid discharged to the outer circumference of the impeller 70 is basically introduced into the volute section 350, where it is pressurized. After this, the pressurized liquid is introduced into the discharge passage 391 and discharged to the outside of the pump 1 via the discharge port 391b.

[0073] As described above, a pump flow path F is formed inside the pump body 10, extending from the inlet 381a to the outlet 391b. Liquid drawn into the pump body 10 from the inlet 381a flows through the pump flow path F and is discharged from the outlet 391b.

[0074] In this embodiment, the pump flow path F includes the suction passage 381, the impeller flow path 740 (inlet passage 750 and centrifugal passage 760), the volute section 350, and the discharge passage 391 as described above.

[0075] In this embodiment, a certain clearance is provided between the casing 30 and the impeller 70 to ensure the rotation of the impeller 70. As a result, a portion of the liquid introduced into the impeller flow path 740 from the intake port 381a and discharged to the outer circumference of the impeller 70 from the discharge port 762 recirculates through the clearance into the cylindrical portion 722 from the outer circumference of the impeller 70.

[0076] In this embodiment, a return path 360 is formed between the casing 30 and the impeller 70, through which liquid circulates from the outer circumference of the impeller 70 into the cylindrical portion 722. However, if a large amount of liquid flows through the return path 360, some of the accelerated and pressurized liquid will not be discharged, thus reducing the pump efficiency.

[0077] In this embodiment, a groove 312 is formed in the casing 30 into which the front end 722a of the cylindrical portion 722 is inserted, thereby providing a labyrinth structure 361 formed by the cylindrical portion 722 and the groove 312 in the return path 360. This increases the flow resistance in the return path 360, thereby suppressing the flow of liquid into the return path 360.

[0078] However, if a labyrinth structure 361 is provided on the inner circumference side of the return path 360 by forming a groove 312 in the casing 30 into which the front end 722a of the cylindrical portion 722 is inserted, the wall portion of the casing 30 (inner wall portion 313) will be present on the inner circumference side of the cylindrical portion 722. As a result, a step is formed between the cylindrical portion 722 and the inner wall portion 313 that widens significantly downstream. When such a step is formed, the flow in the main path of the pump from the intake port 381a side is disturbed, which may reduce the pump efficiency. As the main path of the pump widens abruptly at the step, a pressure drop occurs near the step, which promotes the flow in the return path 360, and as a result, the pump efficiency may also decrease.

[0079] According to this embodiment, the decrease in pump efficiency can be more reliably suppressed.

[0080] Specifically, as shown in Figures 3 to 6 and Figure 8, an extended portion 726 is formed around the entire circumference of the inner side of the front shroud 720. The front surface of the extended portion 726 faces the rear surface of the inner wall portion 313, which is located on the inner circumference side of the groove portion 312.

[0081] Thus, in this embodiment, an extended portion 726 is formed on the front shroud 720, having an opposing surface 726a (front: one side in the axial direction) that faces the end surface 313a (rear surface: the other side in the axial direction: the end surface on the 710 side in the axial direction) of the inner wall portion 313. By doing so, a step that significantly widens in diameter downstream is not formed between the cylindrical portion 722 and the wall portion (inner wall portion 313) of the casing 30. This suppresses the occurrence of a pressure drop near the inner circumference of the return path 360 (near the discharge port 360b), thereby suppressing the flow of liquid into the return path 360 and preventing a decrease in pump efficiency.

[0082] Thus, in this embodiment, a decrease in pump efficiency can be suppressed without arranging other components in the return path 360. This also suppresses the generation of sliding losses, noise, and vibration, as well as the generation of impurities due to wear of other components and the generation of vortices due to the presence of other components.

[0083] Furthermore, in this embodiment, the front shroud 720 is provided with an extended portion 726 having an opposing surface 726a that faces the end face 313a of the inner wall portion 313, thereby making the labyrinth structure 361 formed in the return path 360 more complex. This makes it possible to more reliably suppress the flow of liquid into the return path 360.

[0084] In this embodiment, the extended portion 726 is formed such that its opening diameter is approximately the same as the opening diameter of the inner wall portion 313.

[0085] This makes it possible to more reliably suppress turbulence in the flow of the main path of pump 1, and thus more reliably suppress the decrease in pump efficiency. In addition, the flow in the main path becomes smoother, and the flow in the main path can block the outlet (discharge port 360b) of the return path 360. This makes it possible to further increase the flow resistance in the return path 360, thereby improving pump efficiency.

[0086] In this embodiment, the inner surface 726b of the extension portion 726 and the rear surface 725 of the front shroud body portion 721 (shroud body portion) are connected to form a substantially continuous curved surface. Specifically, the surface formed by the inner surface 726b of the extension portion 726 and the rear surface 725 of the front shroud body portion is a smooth convex curved surface without any recesses or bends.

[0087] This minimizes pressure drops and vortex flow generation on the inner surface 726b of the extension portion 726 and the rear surface 725 of the front shroud body. This also allows for more reliable suppression of liquid flow to the return path 360, thereby improving pump efficiency.

[0088] Furthermore, in this embodiment, the end face 313a of the inner wall portion 313 and the opposing surface 726a of the extended portion 726 are substantially parallel.

[0089] This makes it possible to minimize the cross-sectional area of ​​the return path 360 while ensuring a predetermined clearance when it is necessary to provide a certain clearance between the casing 30 and the impeller 70. By making the end face 313a of the substantially parallel inner wall portion 313 and the opposing face 726a of the extended portion 726 substantially perpendicular to the rotation axis, the flow resistance of the return path 360 can be maximized when a predetermined clearance is ensured. This makes it possible to further improve the pump efficiency.

[0090] In this embodiment, a projection 314 is formed on the surface (inner surface 311) of the casing 30 facing the impeller 70. Specifically, a projection 314 is formed on the top wall 310 of the casing 30 at the outermost part of the impeller 70 (front shroud 720), projecting rearward (towards the impeller 70) and having a triangular cross-sectional shape. The part of the top wall 310 where the projection 314 is formed is a wall that defines the inner circumference of the volute portion 350, and the projection 314 is formed by making the rear end of this wall projection rearward. The projection 314 is formed around the entire circumference. The outer surface 314a (outer circumference side surface) of the projection 314 is a vertical surface extending in the front-rear direction (axial direction), and the inner surface 314b (inner circumference side surface) is an inclined surface that slopes rearward and outward. This suppresses turbulence in the flow of liquid within the volute portion 350.

[0091] A notch 727 is formed in the impeller 70 at a location corresponding to the projection 314, having a surface 727a that is substantially parallel to the surface of the projection 314 (inner surface 314b). Specifically, an inclined surface that slopes rearward and outward is formed at the outermost front end of the front shroud body 721 (shroud body). In this way, a notch 727 is formed behind the projection 314, having a surface 727a that is substantially parallel to the surface of the projection 314 (inner surface 314b). In this embodiment, the notch 727 is also formed around the entire circumference.

[0092] Thus, in this embodiment, by forming the protrusion 314 and the notch 727 corresponding to the protrusion 314, the return path 360 is made more complex in structure, and the flow of liquid into the return path 360 can be suppressed more reliably.

[0093] Specifically, a labyrinth structure 362 is formed on the outer circumference of the return path 360, consisting of protrusions 314 and notches 727. This increases the flow resistance in the return path 360, thereby suppressing the flow of liquid into the return path 360.

[0094] The flow within the volute section 350 can block the inlet (inlet 360a) of the return path 360. This increases the flow resistance in the return path 360, further improving pump efficiency. Furthermore, by making the inner surface 314b of the projection 314 and the surface 727a of the notch 727 approximately parallel, the flow resistance of the return path 360 can be maximized when a predetermined clearance is secured. This further improves pump efficiency.

[0095] As described above, the pump 1 according to this embodiment can suppress a decrease in pump efficiency without placing other members in the return path 360 by changing the shape of the main path and the return path 360 of the pump 1. By not placing other members in the return path 360, it is possible to suppress sliding losses, noise, vibration, generation of impurities due to wear of other members, and generation of vortex flow due to the presence of other members.

[0096] (Note) The above description of embodiments discloses the following technology.

[0097] (Technology 1) The pump of Technology 1 comprises a casing having an intake passage formed with an intake port for drawing in liquid and a discharge passage formed with an outlet for discharging the drawn-in liquid, and an impeller housed in the casing and rotating about an axis. The impeller comprises a blade portion that accelerates the liquid by rotational centrifugal force and a first shroud covering the side of the blade portion facing the intake passage. The first shroud comprises a shroud body portion to which a plurality of the blade portions are connected in series, and an intake port mouth portion connected to the inner circumference side of the shroud body portion and communicating with the intake passage. The casing has a groove portion into which the tip of the intake port mouth portion is inserted, and an inner wall portion located on the inner circumference side of the groove portion. A return path is formed between the casing and the first shroud, which circulates from the outer circumference side of the impeller into the intake port mouth portion. The return path has a labyrinth structure on its inner circumference formed by the intake mouth portion and the groove portion. The first shroud has an extended portion formed thereon that faces the end face on the wing portion side in the axial direction of the inner wall portion.

[0098] According to the pump of Technology 1, a step that significantly widens on the downstream side can be prevented from being formed between the intake mouth and the inner wall of the casing, thereby suppressing pressure drops near the inner circumference of the return path. As a result, the flow of liquid into the return path is suppressed, and a decrease in pump efficiency can be prevented.

[0099] According to the pump of Technology 1, it is possible to suppress the decrease in pump efficiency without placing any components in the return path. As a result, it is also possible to suppress the generation of sliding loss, noise, and vibration. Therefore, it is possible to suppress the decrease in pump efficiency while suppressing the generation of sliding loss, noise, and vibration. Furthermore, by not placing any components in the return path, it is possible to suppress the generation of impurities due to wear of components and the generation of vortex flow due to the presence of components, thereby more reliably suppressing the decrease in pump efficiency.

[0100] Furthermore, by providing the first shroud with an extended portion having an opposing surface that faces the end face of the inner wall, it becomes possible to make the labyrinth structure formed in the return path more complex, thereby further suppressing the flow of liquid into the return path.

[0101] (Technology 2) In addition to the configuration of Technology 1, the pump of Technology 2 has an opening diameter of the extension portion that is approximately the same as the opening diameter of the inner wall portion.

[0102] According to the pump of Technology 2, it becomes possible to more reliably suppress turbulence in the flow of the main path of the pump, thereby more reliably suppressing the decrease in pump efficiency. In addition, the flow in the main path becomes smoother, and the flow in the main path can block the outlet of the return path. As a result, the flow resistance in the return path can be increased, making it possible to further improve pump efficiency.

[0103] (Technology 3) In addition to the configuration of Technology 1 or Technology 2, the pump of Technology 3 is connected such that the inner surface of the extension portion and the inner surface of the shroud body portion form a substantially continuous curved surface.

[0104] According to the pump of Technology 3, it is possible to minimize pressure drops and the generation of vortices, which in turn allows for greater suppression of liquid flow into the return path, thereby improving pump efficiency.

[0105] (Technology 4) The pump of Technology 4 has, in addition to the configuration of any of Technology 1 to Technology 3, the end face and the opposing face are substantially parallel.

[0106] According to the pump of Technology 4, when it is necessary to provide a certain axial clearance between the casing and the impeller, it is possible to minimize the cross-sectional area of ​​the return path while ensuring the predetermined clearance. Furthermore, by making the end face and the opposing face approximately parallel, it becomes possible to maximize the flow resistance of the return path when the predetermined clearance is ensured, thereby further improving the pump efficiency.

[0107] (Technology 5) The pump of Technology 5, in addition to the configuration of any of Technology 1 to Technology 4, has a projection formed on the surface of the casing facing the impeller, and a notch is formed in the part of the impeller corresponding to the projection, having a surface substantially parallel to the surface of the projection.

[0108] According to the pump of technology 5, it becomes possible to make the return path a more complex structure, thereby making it possible to further suppress the flow of liquid into the return path.

[0109] [Other] The contents of the pump relating to this disclosure have been described above, but it will be obvious to those skilled in the art that the invention is not limited to these descriptions and that various modifications and improvements are possible.

[0110] For example, this disclosure can be applied to embodiments in which the configurations shown in the above embodiments and their variations are modified, replaced, added, or omitted. It is also possible to combine the components described in the above embodiments and their variations to create new embodiments.

[0111] In the above embodiment and its modifications, an example was given in which the opening diameter of the extension portion 726 and the opening diameter of the inner wall portion 313 are approximately the same. However, it is also possible to make the opening diameter of the extension portion 726 smaller than the opening diameter of the inner wall portion 313. Even in this case, it is possible to prevent the formation of a step that significantly widens on the downstream side, thereby suppressing a pressure drop near the inner circumference of the return path 360 (near the discharge port 360b), suppressing the flow of liquid into the return path 360, and suppressing a decrease in pump efficiency. When the opening diameter of the extension portion 726 is smaller than the opening diameter of the inner wall portion 313, it is also possible to suppress recirculation by introducing liquid from the discharge side of the return path to apply reverse pressure to the return path.

[0112] The extended portion 726 can also be simply composed of a projection (flange-shaped projection) that protrudes toward the center (axis 60).

[0113] In the above embodiment and its modifications, an example was given in which the end face 313a of the inner wall portion 313 and the opposing surface 726a of the extended portion 726 are horizontal planes (planes perpendicular to the direction of rotation axis). However, it is also possible for the end face 313a of the inner wall portion 313 and the opposing surface 726a of the extended portion 726 to be inclined surfaces.

[0114] The casing, impeller, and other detailed specifications (shape, size, layout, etc.) can also be modified as needed.

[0115] As described above, the pump according to this disclosure can suppress the generation of sliding loss, noise, and vibration while suppressing a decrease in pump efficiency. Therefore, the pump according to this disclosure can be used as a pump for various purposes, including household and commercial use.

[0116] 1 Pump 10 Pump body 100 Seal material 110 Bearing plate 130 Screw 20 Rotating body 30 Casing 310 Top wall 311 Inner surface 312 Groove 313 Inner wall 313a End face 314 Protrusion 314a Outer surface 314b Inner surface 320 Peripheral wall 321 Inner surface 324 Tongue 330 Pump chamber 340 Impeller housing chamber 350 Volute section 350a Starting point 350b End point 360 Return path 360a Inlet 360b Discharge port 361, 362 Labyrinth structure 370 Front shaft fixing part 371 Protrusion 372 Bearing part 373 Support rib 380 Suction pipe 380a Rear end 380b Flange section 381 Intake passage 381a Intake port 381b Outlet 390 Discharge pipe 390a Flange section 391 Discharge passage 391a Inlet 391b Discharge port 40 Drive block 410 Separation wall 420 Bottom section 421 Rib 430 Peripheral wall section 440 Flange section 450 Storage section 460 Magnetic drive section 470 Control section 480 Molded resin 50 Housing 510 Rotating body storage chamber 60 Shaft 70 Impeller 710 Blade section 720 Front shroud (first shroud) 721 Front shroud body section (shroud body section) 722 Cylindrical section (intake mouth section) 722a Front end (tip) 722b Rear end 723 Inner end 724 Outer end 725 Rear surface 726 Extension 726a Opposing surface 726b Inner surface 727 Notch 727a Surface 730 Rear shroud (second shroud) 730a Through hole 731 Inner end 732 Outer end 733 Front surface 740 Impeller flow path 750 Inlet path 760 Centrifugal flow path 761 Inlet 762 Outlet 80 Magnetically driven part 810 Fixing member 820 Magnet part 821 Magnet body 822 Magnet cover 830 Bearing 831 Through hole 90 Neck part

Claims

1. A casing having an intake passage formed with an intake port for drawing in liquid and an outlet passage formed with an outlet for discharging the drawn-in liquid; an impeller housed in the casing and rotating about an axis; the impeller comprising: a blade portion for accelerating liquid by rotational centrifugal force; and a first shroud covering the side of the blade portion facing the intake passage; the first shroud comprising: a shroud body portion to which the blade portion is connected; and an intake mouth portion connected to the inner circumference of the shroud body portion and communicating with the intake passage; the casing having a groove portion into which the tip of the intake mouth portion is inserted, and an inner wall portion located on the inner circumference side of the groove portion; and a return path forming between the casing and the first shroud, allowing fluid to circulate from the outer circumference of the impeller into the intake mouth portion. The return path has a labyrinth structure formed by the intake mouth portion and the groove portion on its inner circumference, and the first shroud has an extended portion formed thereon that faces the end face on the blade portion side in the axial direction of the inner wall portion, in a pump.

2. The pump according to claim 1, wherein the opening diameter of the extended portion is substantially the same as the opening diameter of the inner wall portion.

3. The pump according to claim 1 or claim 2, wherein the inner surface of the extension portion and the inner surface of the shroud body portion are connected in such a way that they form a substantially continuous curved surface.

4. The pump according to claim 1 or claim 2, wherein the end face and the opposing face are substantially parallel.

5. The pump according to claim 1 or claim 2, wherein a projection is formed on the surface of the casing facing the impeller, and a notch is formed in the portion of the impeller corresponding to the projection, having a surface substantially parallel to the surface of the projection.

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