pump

Abstract

To obtain a pump that can suppress the generation of sliding losses, noise, and vibration while also suppressing a decrease in pump efficiency. [Solution] The pump 1 comprises a casing 30 and an impeller 70, the impeller 70 having a first shroud 720 covering the blade portion 710. The casing 30 has a groove 312 into which the tip 722a of the intake mouth portion 722 of the first shroud 720 is inserted, and an inner wall portion 313 located on the inner circumference side of the groove 312. A return path 360 is formed between the casing 30 and the first shroud 720, having a labyrinth structure 361 on the inner circumference side formed by the intake mouth portion 722 and the groove 312. The first shroud 720 has an extended portion 726 having an opposing surface 726a that faces the end face 313a of the inner wall portion 313 on the blade portion 710 side in the axial direction.

Description

Technical Field

[0001] The present disclosure relates to a pump.

Background Art

[0002] Conventionally, there is known a pump including 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 inlet mouth portion communicating with the suction passage, and an impeller housed in the casing and rotating about an axis.

[0003] In such a pump, generally, a return path that circulates from the outer peripheral side of the impeller into the inlet mouth portion is formed between the casing and the impeller. 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 will decrease.

[0004] Therefore, it has been proposed to provide a labyrinth structure formed by the inlet mouth portion and a groove portion in the return path by forming a groove portion in the casing into which the tip of the inlet 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, so that 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 inlet mouth portion is inserted, the wall portion of the casing exists on the inner peripheral side of the inlet mouth portion. Therefore, a step is formed on the downstream side where the diameter significantly expands between the inlet mouth portion and the wall portion of the casing. When such a step is formed, the flow of the main path of the pump from the inlet side is disturbed, so there is a risk that the pump efficiency will decrease. In addition, since the main path of the pump rapidly expands at the step portion, a pressure drop occurs in the vicinity of the step portion, which promotes the flow of the return path, and there is also a risk that the pump efficiency will decrease accordingly.

[0006] Therefore, as shown in Patent Document 1 below, it has been proposed to interpose a sliding member between the intake mouth portion and the casing to shield the return path, thereby suppressing the flow in the return path even when the pressure drops near the stepped portion. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2008-240655 [Overview of the project] [Problems that the invention aims to solve]

[0008] While the configuration disclosed in Patent Document 1 above can suppress a decrease in pump efficiency, it is preferable to also suppress the generation of sliding losses, noise, and vibration.

[0009] Therefore, the purpose of this disclosure is to provide a pump that can suppress the generation of sliding loss, noise, and vibration while also suppressing a decrease in pump efficiency. [Means for solving the problem]

[0010] 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, an impeller housed in the casing and rotating about an axis, wherein the impeller comprises a plurality of blades that accelerate the liquid by rotational centrifugal force, and a first shroud covering the intake passage side of the blades, the first shroud comprising a shroud body portion on which the plurality of blades are connected, and an intake port mound connected to the inner circumference of the shroud body portion and communicating with the intake passage The impeller comprises a casing and a first shroud, the casing having a groove 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, a return path formed between the casing and the first shroud that circulates from the outer circumference side of the impeller into the intake mouth portion, the return path having a labyrinth structure on the inner circumference side formed by the intake mouth portion and the groove portion, and the first shroud having an extended portion having an opposing surface that faces the end face on the blade portion side in the axial direction of the inner wall portion. [Effects of the Invention]

[0011] According to this disclosure, it is possible to obtain a pump that can suppress the generation of sliding loss, noise, and vibration while also suppressing a decrease in pump efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view showing an example of a pump. [Figure 2] This is a cross-sectional view showing an example of a pump. [Figure 3] This is a perspective view from one side of the first shroud and impeller section of an example pump. [Figure 4] This is a perspective view of the first shroud and impeller section of an example pump, seen from the other side. [Figure 5] This is a rear view showing the first shroud and impeller section of an example pump. [Figure 6]Rear view showing a first shroud and blades included in an example of a pump. [Figure 7] Rear view showing a casing included in an example of a pump. [Figure 8] Figure showing a partially enlarged view of Figure 2.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments will be described in detail with reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters, or duplicate descriptions of substantially the same configurations may be omitted.

[0014] Note that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0015] In the following description, the direction of the rotation axis of the impeller is defined as the front-rear direction, and the suction port side in the rotation axis direction is defined as the front side for description.

[0016] (Embodiment) As shown in FIGS. 1 and 2, the pump 1 according to the present embodiment includes a pump body 10 that constitutes an outer shell, and a rotating body 20 that is housed in a rotating body housing chamber 510 formed inside the pump body 10.

[0017] The pump body 10 is composed of a casing 30 in which a pump chamber 330 that opens to the rear is formed, and a drive block 40 in which a storage portion 450 that opens to the front is formed (see FIG. 2).

[0018] And, the storage portion 450 of the drive block 40 communicates with the pump chamber 330 of the casing 30, and a rotating body housing chamber 510 that houses the entire rotating body 20 is formed by the storage portion 450 and the pump chamber 330.

[0019] As shown in FIG. 2, the drive block 40 has a partition wall 410, a magnetic drive unit 460, a control unit 470, and a mold resin 480 forming an outer shell.

[0020] The partition wall 410 is made of synthetic resin and can be formed, for example, of polyphenylene sulfide (PPS) resin.

[0021] This partition wall 410 is formed in a bottomed cylindrical container shape that opens forward, and is composed of a bottom portion 420, a peripheral wall portion 430 extending forward from the outer periphery of the bottom portion 420, and a flange portion 440 protruding radially outward from the front edge portion of the peripheral wall portion 430. In the present embodiment, the flange portion 440 is formed over the entire circumferential direction of the peripheral wall portion 430.

[0022] And the bottom portion 420 and the peripheral wall portion 430 define a storage portion 450 that has an open front surface and a rear surface closed by the bottom portion 420.

[0023] As described above, in the present embodiment, the casing 30 and the partition wall 410 constitute a housing 50 in which a rotor housing chamber 510 for housing the rotor 20 is formed.

[0024] At the center of the bottom portion 420 of the storage portion 450 (the center of the inner back portion within the storage portion 450), a cylindrical rib (rear shaft fixing portion: shaft support portion) 421 protruding forward is formed, and the rear end portion of a shaft (rotating shaft) 60 that rotatably supports the rotor 20 is inserted into this cylindrical rib 421. This shaft 60 can be formed, for example, of ceramics.

[0025] Note that the shaft 60 is held non-rotatably by the partition wall 410. Such a configuration can be formed, for example, by making the contour shape of the rear end portion of the shaft 60 D-shaped and providing a D-shaped portion corresponding to the rear end portion of the shaft 60 inside the cylindrical rib 421.

[0026] Furthermore, in this embodiment, a stator serving as a magnetic drive unit 460 is arranged on the outer circumference of the peripheral wall portion 430. By driving this 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.

[0027] The rotating body 20 has an impeller 70 as a pump section located at the 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 (connecting section) 90 (see Figure 2). In this embodiment, the impeller 70, the magnetic drive section 80, and the neck section (connecting 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 axis 60).

[0028] The magnetically driven part 80 of the rotating body 20 is housed in the housing section 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 section 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.

[0029] The magnetically driven unit 80 is a rotor housed in the housing unit 450 and rotatably supported by the shaft 60.

[0030] The magnetically driven unit 80 consists of a fixed member 810 made of synthetic resin, a magnet part 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 made from, for example, polyphenylene ether (PPE) resin. The magnet part 820 can be made from a permanent magnet such as ferrite or SmFe. The bearing 830 can be made from a carbon-containing resin sliding material or ceramics.

[0031] Furthermore, in this embodiment, the fixing member 810 is integrally formed with the neck portion (connecting portion) 90 and the rear shroud (second shroud) 730, as shown in Figure 2.

[0032] Furthermore, the magnet section 820 is formed from 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 (rotor) 80.

[0033] Furthermore, a through hole 831 is formed in the center of the bearing 830, and by inserting the shaft 60 through this through hole 831, the rotating body 20 is supported so as to be able to rotate freely.

[0034] In this configuration, the magnetically driven rotor 80 is positioned such that the magnet portion 820 faces the magnetic drive portion 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 rotor 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 (first shroud) 720 that covers the front side (one side in the axial direction) of each blade 710, and a rear shroud (second shroud) 730 that covers the rear side (the other side in the axial direction) of each blade 710.

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

[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 circumference end 731 of the rear shroud 730, via a neck portion (connecting portion) 90. In this embodiment, the front surface 733 of the rear shroud 730 (the inner surface on the second shroud side of the centrifugal flow path 760, which will be described later) is a flat surface that extends in the radial direction.

[0038] Furthermore, in this embodiment, the rear shroud 730 and the magnetically driven part 80 are formed by insert molding. That is, with the magnet part 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 part (connecting part) 90 and the fixing member 810, thereby integrally forming the rear shroud 730 and the magnetically driven part 80.

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

[0040] Each wing portion 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 blade portion 710 is attached to the front surface (the inner surface on the second shroud side of the centrifugal flow path 760) 733 of the rear shroud 730, and each blade portion 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 body 721 and the rear shroud 730, there are multiple circumferentially formed spaces defined by two adjacent blade sections 710, 710, the front shroud 720, and the rear shroud 730, with openings on the radially inward and radially outward sides. Each of these spaces forms a centrifugal passage 760, which is part of the impeller passage 740 formed within the impeller 70. The radially inward opening of each centrifugal passage 760 serves as an inlet 761, and the radially outward opening serves as an outlet 762.

[0043] Furthermore, in this embodiment, an introduction passage 750, which forms part of the impeller passage 740, is formed radially inside the centrifugal passage 760.

[0044] This inlet passage 750 is formed to extend axially from the front end (tip) 722a side of the cylindrical portion 722 to the through hole 730a of the rear shroud 730, and the inlet 761 of each centrifugal passage 760 is in communication with the inlet passage 750.

[0045] When the impeller 70 with this configuration is rotated, the liquid introduced into the centrifugal flow path 760 from the inlet passage 750 through the inlet port 761 is accelerated by the centrifugal force of the rotating impeller 70 and discharged radially outward from the discharge port 762.

[0046] The liquid discharged from the discharge port 762 to the outer circumference of the impeller 70 is then introduced into the volute section 350, where it is pressurized.

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

[0048] The casing 30 comprises a top wall 310 and a peripheral wall 320 that protrudes rearward from the periphery of the top wall 310, and is formed in the shape of a container that opens to the rear. 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] Furthermore, 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. At this time, the impeller 70 is positioned such that the rear surface of its outer periphery (the rear surface on the outer periphery side of the rear shroud 730) faces the front surface of the inner periphery of the flange portion 440.

[0050] In this embodiment, the rear surface of the peripheral wall 320 is brought into contact with the outer circumferential surface 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 multiple 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. At this time, 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] Furthermore, 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, opening 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 fastening 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] Furthermore, in this embodiment, with the impeller 70 positioned in the pump chamber 330, the suction passage 381 is connected to the introduction passage 750 of the impeller passage 740.

[0055] Specifically, the rear end 380a of the suction pipe 380 is made to protrude into the pump chamber 330, and an outlet 381b that opens to the rear is formed on 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] Furthermore, 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 fastening 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 this inlet 391a. The discharge port 391b opens in a direction intersecting the axial direction (perpendicular in this embodiment).

[0060] In this embodiment, the discharge passage 391 is formed to extend tangentially near the end point 350b of the spirally formed volute section 350. That is, the liquid in the discharge passage 391 flows mainly tangentially near the end point 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. This 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] Furthermore, the casing 30 is provided with a front shaft fixing part (shaft support part) 370 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 this front shaft fixing part 370.

[0063] Incidentally, 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, reference numeral 110 denotes a bearing plate that receives the thrust load applied to the bearing 830. This bearing plate 110 is positioned on both the front and rear sides of the bearing 830 and prevents wear on the parts of the casing 30 that face the magnetic driven part 80 (the rear end of the cylindrical bearing part 372 and the front end of the rib 421) when the magnetic driven part 80 is rotated.

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

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

[0068] In this embodiment, the impeller flow path 740 is configured 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 protrusion 371 is placed in the introduction passage 750 as a flow direction changing section, and this protrusion 371 changes the flow direction of the liquid flowing axially to be closer to the radial direction. This makes it possible to introduce the liquid from the inlet 761 into the centrifugal passage 760 more smoothly.

[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 part 820 of the rotating body 20 is attracted to and repelled by the magnetic drive unit 460, causing the magnetic driven part 80 to rotate around the shaft 60, thereby causing the impeller 70 to rotate around the shaft 60 which extends back and forth.

[0072] As the impeller 70 rotates, the liquid introduced into the impeller flow path 740 via the intake passage 381 from the intake port 381a 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 then 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] Thus, 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] Furthermore, 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 from the outer circumference of the impeller 70 into the cylindrical portion (intake mouth) 722.

[0076] Thus, 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 (inlet mouth) 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, resulting in a decrease in pump efficiency.

[0077] Therefore, in this embodiment, a groove 312 is formed in the casing 30 into which the front end (tip) 722a of the cylindrical portion (inlet mouth) 722 is inserted, thereby providing a labyrinth structure 361 formed by the cylindrical portion (inlet mouth) 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 (tip) 722a of the cylindrical part (inlet mouth) 722 is inserted, the wall portion (inner wall portion 313) of the casing 30 will be present on the inner circumference side of the cylindrical part (inlet mouth) 722. As a result, a step is formed between the cylindrical part (inlet mouth) 722 and the wall portion (inner wall portion 313) of the casing 30, which expands significantly on the downstream side. When such a step is formed, the flow in the main path of the pump from the inlet 381a side becomes turbulent, which may reduce the pump efficiency. In addition, because 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, which may also reduce the pump efficiency.

[0079] Therefore, this embodiment is designed to more reliably suppress a decrease in pump efficiency.

[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 (first 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] As described above, in this embodiment, an extended portion 726 is formed on the front shroud (first shroud) 720, having an opposing surface (front: one side in the axial direction) 726a that faces the end surface (rear surface: the other side in the axial direction: the end surface on the 710 side in the axial direction) 313a of the inner wall portion 313. This prevents the formation of a step that significantly widens in diameter downstream between the cylindrical portion (inlet mouth) 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 (first shroud) 720 is provided with an extended portion 726 having an opposing surface (front: one side in the axial direction) 726a that faces the end surface (rear surface: the other side in the axial direction: the end surface on the 710 side in the axial direction) 313a of the inner wall portion 313, thereby making the labyrinth structure 361 formed in the return path 360 a more complex structure. This makes it possible to more reliably suppress the flow of liquid into the return path 360.

[0084] Furthermore, 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 a 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] Furthermore, in this embodiment, the inner surface 726b of the extension portion 726 and the rear surface (inner surface) 725 of the front shroud body portion (shroud body portion) 721 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 ensures more reliable suppression of liquid flow to the return path 360, thereby improving pump efficiency.

[0088] Furthermore, in this embodiment, the end face (rear face: the other side in the axial direction: the end face on the 710 side in the axial direction) 313a of the inner wall portion 313 and the opposing face (front face: the one side in the axial direction) 726a of the extended portion 726 are made to be 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. Furthermore, by making the end face (rear face: the other side in the axial direction: the end face on the 710 side in the axial direction) 313a of the substantially parallel inner wall portion 313 and the opposing face (front face: the one side in the axial direction) 726a of the extension 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. In this case, the projection 314 is formed around the entire circumference. Furthermore, the outer surface (outer surface) 314a of the projection 314 is a vertical surface extending in the front-rear direction (axial direction), and the inner surface (inner surface) 314b is an inclined surface that slopes rearward and outward. This helps to suppress disturbance in the flow of liquid within the volute portion 350.

[0091] Furthermore, a notch 727 is formed in the impeller 70 at the portion 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 portion (shroud body portion) 721. In this way, a notch 727 having a surface 727a that is substantially parallel to the surface of the projection 314 (inner surface 314b) is formed behind the projection 314. In this embodiment, this 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 to have a more complex structure, thereby more reliably suppressing the flow of liquid into the return path 360.

[0093] Specifically, a labyrinth structure 362, formed by protrusions 314 and notches 727, is also formed on the outer circumference of 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.

[0094] Furthermore, 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, thereby improving pump efficiency. In addition, by making the inner surface 314b of the protrusion 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 is designed to suppress a decrease in pump efficiency without placing other components in the return path 360 by changing the shape of the main path and the return path 360 of the pump 1. Furthermore, by not placing other components in the return path 360, it is possible to suppress 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 vortex flow due to the presence of other components.

[0096] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0097] (Technology 1) 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, wherein the impeller comprises a plurality of blades that accelerate the liquid by rotational centrifugal force and a first shroud covering the intake passage side of the blades, wherein the first shroud comprises a shroud body portion on which the plurality of blades are connected and an intake port mouth portion connected to the inner circumference of the shroud body portion and communicating with the intake passage A pump wherein the casing has a groove 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 is formed between the casing and the first shroud, which circulates from the outer circumference side of the impeller into the intake mouth portion, and the return path has a labyrinth structure on the inner circumference side formed by the intake mouth portion and the groove portion, and the first shroud has an extended portion which has an opposing surface that faces the end face on the blade portion side in the axial direction of the inner wall portion.

[0098] This prevents the formation of a significant diameter gap downstream 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, preventing a decrease in pump efficiency.

[0099] Thus, with the pump of Technology 1, it becomes possible to suppress the decrease in pump efficiency without placing any components in the return path. As a result, it becomes possible to suppress the generation of sliding losses, noise, and vibration. Therefore, with the pump of Technology 1, it is possible to suppress the generation of sliding losses, noise, and vibration while suppressing the decrease in pump efficiency. Furthermore, by not placing any components in the return path, it becomes possible to suppress the generation of impurities due to wear of components and the generation of vortices 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) The pump according to Technology 1, wherein the opening diameter of the extended portion is substantially the same as the opening diameter of the inner wall portion.

[0102] This makes it possible to more reliably suppress turbulence in the main flow path of the pump, thereby more reliably suppressing a 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] (Technical 3) The pump according to Technical 1 or Technical 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.

[0104] This minimizes pressure drops and vortex formation, allowing for greater control of liquid flow in the return path and ultimately improving pump efficiency.

[0105] (Technology 4) A pump according to any one of the technologies 1 to 3, wherein the end face and the opposing face are substantially parallel.

[0106] This design allows for minimizing the cross-sectional area of ​​the return path while ensuring a predetermined clearance when a certain axial clearance is required between the casing and the impeller. 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 pump efficiency.

[0107] (Technical 5) A protrusion is formed on the surface of the casing facing the impeller. A pump according to any one of the technologies 1 to 4, wherein a notch is formed in the portion of the impeller corresponding to the projection, the notch having a surface substantially parallel to the surface of the projection.

[0108] This allows for a more complex structure in the return path, thereby further suppressing the flow of liquid into the return path.

[0109] [others] The details of the pump described herein have been explained above, but it will be obvious to those skilled in the art that the pump 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. Furthermore, it is possible to combine the components described in the above embodiments and their variations to create new embodiments.

[0111] Furthermore, in the above embodiment and its modifications, the opening diameter of the extension portion 726 and the opening diameter of the inner wall portion 313 are shown as being 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. This also prevents the formation of a step with a significantly wider diameter on the downstream side, thereby suppressing a pressure drop near the inner circumference of the return path 360 (near the discharge port 360b). This suppresses the flow of liquid into the return path 360 and prevents 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, thereby applying reverse pressure to the return path.

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

[0113] Furthermore, in the above embodiment and its modified examples, the end face 313a of the inner wall portion 313 and the opposing surface 726a of the extension portion 726 are shown as horizontal planes (planes perpendicular to the rotation axis direction). However, it is also possible to make the end face 313a of the inner wall portion 313 and the opposing surface 726a of the extension portion 726 as inclined surfaces.

[0114] Furthermore, the casing, impeller, and other detailed specifications (shape, size, layout, etc.) can be modified as needed. [Industrial applicability]

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

[0116] 1 pump 30 Casing 311 Inner self 312 Groove 313 Inner wall 313a End face 314 Protrusion 360 Return Route 361 Labyrinth structure 381a Inlet 391 Discharge path 391b Discharge port 60 axes 70 Impeller 710 Blade section 720 Front Shroud (First Shroud) 721 Shroud main body 722 Cylindrical section (inhalation port mouth section) 722a Front end (tip) 725 Rear surface (inner surface) 726 Extension section 726a Opposing surface 726b Inner surface 727 Notch

Claims

1. 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, A casing is housed in the aforementioned impeller, which rotates around an axis, Equipped with, The aforementioned impeller is Multiple blades that accelerate the liquid by rotational centrifugal force, A first shroud covering the intake passage side of the vane portion, Equipped with, The first shroud is, A shroud body portion on which multiple wing portions are connected, The air intake mouth portion is connected to the inner circumference of the shroud body and communicates with the air intake passage, Equipped with, The casing has a groove 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. A return path is formed between the casing and the first shroud, which allows air 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. The first shroud has an extended portion formed thereon, which has an opposing surface that faces the end face on the wing side in the axial direction of the inner wall portion. pump.

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

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

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

5. A protrusion is formed on the surface of the casing facing the impeller. 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. The pump according to claim 1 or claim 2.

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