pump

Abstract

To obtain a pump that can more reliably suppress molding defects in the casing. [Solution] The pump 1 is equipped with an impeller 70. Furthermore, the pump 1 is equipped with a resin casing 30 in which a volute portion 350 is formed on the outer circumference side of the impeller 70 when the impeller 70 is housed. A hole 315 is formed on the surface 311 of the casing 30 facing the impeller 70, with the hole recessed on the side opposite to the impeller 70.

Description

Technical Field

[0001] This disclosure relates to a pump.

Background Art

[0002] Conventionally, as shown in Patent Document 1 below, a pump is known that includes an impeller and a casing in which a volute portion is formed at a portion on the outer peripheral side of the impeller in a state where the impeller is accommodated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such a casing can be formed by resin molding using a mold. And when manufacturing a resin casing using a mold, it is preferable to be able to suppress the occurrence of molding defects such as sink marks and warpage.

[0005] Therefore, an object of the present disclosure is to obtain a pump that can more reliably suppress the occurrence of molding defects in the casing.

Means for Solving the Problems

[0006] A pump according to one aspect of the present disclosure includes an impeller and a resin casing in which a volute portion is formed at a portion on the outer peripheral side of the impeller in a state where the impeller is accommodated, and a hole portion that is recessed on the side opposite to the impeller side is formed on the surface of the casing facing the impeller.

Effects of the Invention

[0007] According to this disclosure, it is possible to obtain a pump that can more reliably suppress the occurrence of molding defects in the casing. [Brief explanation of the drawing]

[0008] [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] This is a rear view showing the first shroud and impeller section of an example pump. [Figure 7] This is a rear view showing the casing of an example of a pump. [Figure 8] This is a magnified view of a portion of Figure 7. [Modes for carrying out the invention]

[0009] 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 or redundant explanations of substantially identical configurations may be omitted.

[0010] The attached 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.

[0011] Furthermore, 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.

[0012] (Embodiment) As shown in FIGS. 1 and 2, the pump 1 according to the present embodiment includes a pump body 10 that forms an outer shell, and a rotating body 20 that is housed in a rotating body housing chamber 510 formed inside the pump body 10.

[0013] The pump body 10 is composed of a casing 30 in which a pump chamber 330 opening rearward is formed, and a drive block 40 in which a storage portion 450 opening forward is formed (see FIG. 2).

[0014] The storage portion 450 of the drive block 40 communicates with the pump chamber 330 of the casing 30, and a rotating body storage chamber 510 that houses the entire rotating body 20 is formed by the storage portion 450 and the pump chamber 330.

[0015] 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 that forms an outer shell.

[0016] The partition wall 410 is made of a synthetic resin, and can be formed of, for example, polyphenylene sulfide (PPS) resin.

[0017] 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 that extends forward from the outer periphery of the bottom portion 420, and a flange portion 440 that protrudes 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.

[0018] The bottom portion 420 and the peripheral wall portion 430 define a storage portion 450 whose front surface is open and whose rear surface is closed by the bottom portion 420.

[0019] Thus, in the present embodiment, the casing 30 and the partition wall 410 constitute a housing 50 in which a rotating body storage chamber 510 for housing the rotating body 20 is formed.

[0020] A cylindrical rib (rear shaft fixing part: shaft support part) 421 is formed in the center of the bottom 420 of the storage compartment 450 (the center of the back of the storage compartment 450), and the rear end of the shaft (rotating shaft) 60 that rotatably supports the rotating body 20 is inserted into this cylindrical rib 421. This shaft 60 can be made of, for example, ceramics.

[0021] The shaft 60 is held in a non-rotatable position by the separation wall 410. Such a configuration can be formed, for example, by making the contour shape of the rear end of the shaft 60 D-shaped and providing a D-shaped portion corresponding to the rear end of the shaft 60 inside the cylindrical rib 421.

[0022] 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.

[0023] 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).

[0024] 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.

[0025] The magnetically driven unit 80 is a rotor housed in the housing unit 450 and rotatably supported by the shaft 60.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Furthermore, in this embodiment, an introduction passage 750, which forms part of the impeller passage 740, is formed radially inside the centrifugal passage 760.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] The casing 30 is made of synthetic resin and can be formed from, for example, polyphenylene sulfide (PPS) resin.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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).

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] In this embodiment, the impeller flow path 740 is configured to discharge liquid flowing in from the axial front toward the radially outward direction.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] In this embodiment, as described above, a flange portion 380b is formed at the tip of the suction pipe 380. The suction pipe 380 and the upstream pipe are connected by butting the flange portion 380b with the flange portion formed at the tip of the upstream pipe and fixing them with a fastening member such as a quick fastener.

[0072] Thus, if the casing 30 is equipped with an intake pipe (pipe section) 380 into which a flange portion 380b is formed, the casing 30 becomes larger in the radial direction. In particular, when connecting to an upstream pipe (pipe) with a large diameter, the diameter of the intake pipe (pipe section) 380 into which the upstream pipe (pipe) is inserted during connection also becomes larger. Furthermore, if a flange portion 380b is formed on such a large-diameter intake pipe (pipe section) 380, the radial width of the casing 30 becomes even larger.

[0073] Furthermore, in this embodiment, a volute portion 350 is formed in a spiral shape on the outer circumference of the casing 30. This volute portion 350 is formed such that its cross-sectional area gradually increases from the starting point 350a to the ending point 350b. Specifically, the width (radial length) and height (axial length) gradually increase from the starting point 350a to the ending point 350b.

[0074] Furthermore, when attempting to resin mold (integrally mold) such a casing 30, that is, a casing 30 provided with a volute section 350 in which the flow path expands in a helical shape, and a suction pipe 380 into which the joint portion of the upstream piping is inserted during connection, using a mold, it is not possible to construct a mold in the inner diameter direction of the helical flow path expansion portion of the casing 30, and in the axial direction on the impeller 70 side of the suction port 381a and flange section 380b. As a result, this part of the casing 30 becomes thick-walled (lumpy), which may lead to molding defects such as sink marks and warping.

[0075] Therefore, in this embodiment, by forming a hole 315 in the thick-walled portion (block-like portion) located behind the flange portion 380b of the casing 30, it is possible to more reliably suppress molding defects such as sink marks and warping in the casing 30, even when resin molding is performed using a mold.

[0076] In this case, it is conceivable to form a hole 315 on the side of the casing 30, but in this embodiment, a volute portion 350 in which the flow path expands in a spiral shape is provided on the outer circumference of the casing 30, and in order to form a hole 315 on the side of the casing 30, it is necessary to form the hole 315 in front of the volute portion 350. However, when a volute portion 350 in which the height (axial length) gradually increases is formed on the casing 30, it was not possible to secure a sufficient area for forming a hole 315 in front of the volute portion 350.

[0077] Alternatively, the suction tube 380 could be formed from a separate component and fixed to the casing 30 using methods such as retaining or screw fastening. However, forming the suction tube 380 from a separate component may increase manufacturing and management costs due to the increased size and number of parts, and may also lead to variations in shape or connection problems.

[0078] Therefore, when molding the casing 30 with resin, it is preferable to mold the suction pipe 380 as an integral part of the casing.

[0079] Therefore, in this embodiment, even when a casing 30, which is provided with a volute portion 350 in which the flow path expands in a spiral shape and an intake pipe 380 having a flange portion 380b, is resin-molded using a pair of molds divided in one direction, a hole portion 315 can be formed in the thick-walled portion (block-like portion).

[0080] Specifically, a recessed hole 315 is formed on the inner surface (the surface facing the impeller 70) 311 of the top wall 310 of the casing 30, with the recess facing forward (opposite side from the impeller 70).

[0081] This allows for the formation of holes 315 in the casing 30 without interference from the flange portion 380b, even when resin molding is performed using a pair of molds divided in the axial direction (a mold with a simple configuration). This makes it easier to manufacture a casing 30 that is less prone to molding defects such as shrinkage and warping.

[0082] Furthermore, in this embodiment, multiple holes 315 are formed on the inner surface (the surface facing the impeller 70) 311 of the top wall 310.

[0083] Furthermore, the distance L1 between the inner circumferential end face 315a of the hole 315 and the inner circumferential end face 311a of the inner surface (surface facing the impeller 70) 311 is set to be within the range of -40% to +20% of the diameter (maximum radial length) D1 of the hole 315. In addition, the distance L2 between the outer circumferential end face 315b of the hole 315 and the outer circumferential end face 311b of the inner surface (surface facing the impeller 70) 311 is set to be within the range of -40% to +20% of the diameter (maximum radial length) D1 of the hole 315.

[0084] This prevents the formation of extremely thick or thin sections in the casing 30, and also prevents the opening area of ​​the hole 315 from becoming extremely large. This also ensures that the moldability of the casing 30 is maintained while suppressing a decrease in pump efficiency.

[0085] Furthermore, in this embodiment, multiple holes 315 are formed on the inner surface (the surface facing the impeller 70) 311 such that the minimum distance L3 between adjacent holes 315 in the circumferential direction is within the range of -20% to +20% of the diameter D1 of the hole 315 (the maximum tangential distance of the circular arc A1 as the circumference at the center C1).

[0086] This configuration creates multiple axially elongated columnar holes 315 along the circumferential direction. By using axially elongated columnar holes 315, the holes 315 can be formed using pin members when molding the casing 30 with a mold, thereby enabling the casing 30 to be manufactured at a lower cost. Furthermore, by using axially elongated columnar holes 315, turbulence in the vortex flow within each hole 315 can be minimized, thereby preventing a decrease in pump efficiency.

[0087] In this embodiment, multiple (15 in this embodiment) elongated, roughly cylindrical (roughly circular) holes 315 are formed along the circumferential direction. This allows the holes 315 to be formed using existing pins.

[0088] As described above, in this embodiment, multiple elongated, roughly cylindrical (roughly circular) holes 315 are formed along the circumferential direction on the inner surface (the surface facing the impeller 70) 311.

[0089] Furthermore, by providing such holes 315 on the inner surface (the surface facing the impeller 70) 311, the casing 30 is configured to be optimal in terms of moldability and pump efficiency. The reasons for this are explained below.

[0090] First, from the viewpoint of moldability of the resin of the casing 30 (prevention of shrinkage and warping), it is most desirable that the hole shape of the inner surface (the surface facing the impeller 70) 311 be plate-shaped (for example, inner and outer cylinders and radial ribs connecting them). The plate-shaped grooves (holes) formed in this case may be wide or narrow.

[0091] On the other hand, from the standpoint of pump efficiency (energy efficiency of pump 1), if the inner surface (the surface facing the impeller 70) 311 is a smooth plane, no unnecessary vortex flow is generated, resulting in the highest pump efficiency.

[0092] Furthermore, if the vortices generated when holes are formed are made to be "small" and "smooth," the loss of pump efficiency will be reduced.

[0093] However, in the case of holes composed of the plate shape described above, the hole shape is angular, so the vortex flow generated when the hole is formed becomes a "large" and "turbulent" vortex flow. Therefore, in the case of holes composed of a plate shape, the loss of pump efficiency is large.

[0094] Thus, while the moldability of the resin of the casing 30 can be ensured when the holes are made in a plate shape, the loss of pump efficiency becomes significant.

[0095] On the other hand, if the inner surface (the surface facing the impeller 70) 311 is made into a smooth plane, the pump efficiency will be the highest, but it will become impossible to ensure the moldability of the resin of the casing 30.

[0096] In contrast, if the hole shape of the inner surface (the surface facing the impeller 70) 311 is made approximately circular (round hole), the vortex flow that occurs when the hole is formed can be made "smaller" and "smoother," thus reducing the loss of pump efficiency due to the vortex flow.

[0097] Therefore, by providing multiple roughly circular holes 315 along the circumferential direction, and making the diameters D1 and D2 of the holes 315, the distance L1 between the inner circumferential end face 315a of the hole 315 and the inner circumferential end face 311a of the inner surface (the surface facing the impeller 70) 311, the distance L2 between the outer circumferential end face 315b of the hole 315 and the outer circumferential end face 311b of the inner surface (the surface facing the impeller 70) 311, and the distance L3 between adjacent holes 315 in the circumferential direction roughly the same length, the moldability of the resin of the casing 30 can be sufficiently ensured, although not to the same extent as a plate shape, and the loss of pump efficiency due to vortex flow can also be reduced.

[0098] Therefore, as in this embodiment, a configuration in which multiple elongated, substantially cylindrical (approximately circular) holes 315 are formed along the circumferential direction on the inner surface (the surface facing the impeller 70) 311 is the optimal configuration from the viewpoint of moldability of the casing 30 and pump efficiency.

[0099] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0100] (Technical 1) A pump comprising an impeller and a resin casing in which a volute portion is formed on the outer circumference side of the impeller when the impeller is housed, wherein a hole is formed on the surface of the casing facing the impeller, with the hole recessed on the side opposite to the impeller.

[0101] This prevents the formation of thickened sections in the casing, making it possible to more reliably suppress molding defects such as sink marks and warping in the casing during resin molding. Thus, the pump described in Technology 1 can suppress the formation of thickened sections in the casing, thereby suppressing molding defects such as sink marks and warping.

[0102] Furthermore, by forming a hole on the surface of the casing facing the impeller, which is recessed on the opposite side from the impeller, it becomes possible to form the hole in the casing using a pair of molds divided in one direction, even when the outer diameter of the pipe section increases due to the flange section, such as when a pipe section with a flange section for connecting to piping is formed in the casing. In other words, even when using a pair of molds divided in one direction, it becomes possible to form the hole in the casing without being obstructed by the flange section. In particular, even when the diameter of the pipe section increases and the thickness of the area between the flange section and the surface facing the impeller increases, it becomes possible to form the hole using a mold with a simple structure, making it easier to manufacture casings that are less prone to molding defects such as sink marks and warping.

[0103] (Technology 2) The pump according to Technology 1, wherein a plurality of holes are formed.

[0104] This method avoids the formation of extremely thick or thin sections in the casing, as well as the creation of extremely large opening areas in the holes, thus enabling a balance between ensuring the moldability of the casing and suppressing a decrease in pump efficiency.

[0105] (Technology 3) The pump according to Technology 1 or Technology 2, wherein the distance between the inner circumferential end face of the hole and the inner circumferential end face of the opposing surface is within the range of -40% to +20% of the maximum radial length of the hole, and the distance between the outer circumferential end face of the hole and the outer circumferential end face of the opposing surface is within the range of -40% to +20% of the maximum radial length of the hole.

[0106] This method avoids the formation of extremely thick or thin sections in the casing, as well as the creation of extremely large opening areas in the holes, thus enabling a balance between ensuring the moldability of the casing and suppressing a decrease in pump efficiency.

[0107] (Technical 4) The pump according to Technical 2 or Technical 3, wherein a plurality of holes are formed on the opposing surfaces such that the minimum distance between adjacent holes in the circumferential direction is within the range of -20% to +20% of the maximum distance in the tangential direction of the circumference at the center of the hole.

[0108] This method allows for the formation of multiple columnar holes along the circumferential direction. By forming multiple columnar holes along the circumferential direction, it is possible to minimize turbulence in the vortex flow within each hole, thereby preventing a decrease in pump efficiency. Furthermore, since the holes can be formed using pin members when molding the casing with a mold, the casing can be manufactured at a lower cost.

[0109] (Technology 5) A pump according to any one of the technologies from Technology 1 to Technology 4, wherein the hole portion is substantially circular.

[0110] This way, the hole can be formed using existing pins.

[0111] [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.

[0112] 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.

[0113] Furthermore, while the above embodiment and its modifications illustrate a roughly cylindrical (roughly circular) hole 315, it is possible to have holes of various shapes, such as a roughly rectangular prism (roughly square) shape. It is also possible to make the back side of the hole roughly hemispherical.

[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 more reliably suppress molding defects in the casing, 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 surface (facing the impeller) 311a End face on the inner circumference side 311b End face on the outer circumference 315 Hole 315a End face on the inner circumference side 315b End face on the outer circumference 350 Volute section 70 Impeller A1 Circumference Center of hole C1 D1 Diameter (maximum radial length of the hole) D2 Diameter (maximum tangential distance from the center of the hole to the circumference) Distance between the inner end face of the hole L1 and the inner end face of the opposing surface Distance between the outer end face of the L2 hole and the outer end face of the opposing surface L3 Distance between adjacent holes in the circumferential direction

Claims

1. The impeller and A resin casing in which the impeller is housed and a volute portion is formed on the outer circumference side of the impeller, Equipped with, A hole is formed on the surface of the casing facing the impeller, with the hole recessed on the side opposite to the impeller. pump.

2. Multiple holes are formed, The pump according to claim 1.

3. The distance between the inner circumferential end face of the hole and the inner circumferential end face of the opposing surface is set to be within the range of -40% to +20% of the maximum radial length of the hole, while the distance between the outer circumferential end face of the hole and the outer circumferential end face of the opposing surface is set to be within the range of -40% to +20% of the maximum radial length of the hole. The pump according to claim 1 or claim 2.

4. Multiple holes are formed on the opposing surfaces such that the minimum distance between adjacent holes in the circumferential direction is within the range of -20% to +20% of the maximum tangential distance at the center of the hole. The pump according to claim 2.

5. The aforementioned hole is approximately circular in shape. The pump according to claim 1 or claim 2.

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