Pump

Abstract

A pump according to the present disclosure comprises an impeller. The pump according to the present disclosure comprises a resin casing (30) having a volute section (35) formed therein at a position on the outer peripheral side of the impeller when the impeller is in an accommodated state. Holes (315) that are recessed toward the opposite side from the impeller side are formed in the casing (30) in a surface (311) facing the impeller. The present disclosure makes it possible to provide a pump in which molding defects in the casing can reliably be supressed.

Description

Pump

[0001] The present disclosure relates to a pump.

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

[0003] Japanese Patent Application Laid-Open No. 2006-200427

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

[0005] An object of the present disclosure is to obtain a pump capable of more reliably suppressing the occurrence of molding defects in a casing.

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

[0007] According to the present disclosure, it is possible to obtain a pump capable of more reliably suppressing the occurrence of molding defects in a casing.

[0008] FIG. 1 is a plan view showing an example of a pump according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing an example of the pump according to the present embodiment. FIG. 3 is a perspective view of a first shroud and blade portions included in an example of the pump according to the present embodiment as viewed from one side. FIG. 4 is a perspective view of the first shroud and blade portions included in an example of the pump according to the present embodiment as viewed from the other side. FIG. 5 is a rear view showing the first shroud and blade portions included in an example of the pump according to the present embodiment. FIG. 6 is a rear view showing the first shroud and blade portions included in an example of the pump according to the present embodiment. FIG. 7 is a rear view showing a casing included in an example of the pump according to the present embodiment. FIG. 8 is a view showing a partially enlarged view of FIG. 7.

[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 and redundant explanations of substantially identical configurations may be omitted.

[0010] 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.

[0011] 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 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.

[0013] 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).

[0014] 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.

[0015] 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.

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

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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).

[0024] 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.

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

[0026] 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.

[0027] 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.

[0028] 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).

[0029] 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.

[0030] 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.

[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 includes a front shroud 720 that covers the front side (one side in the axial direction) of each blade 710, and a rear shroud 730 that covers the rear side (the other side in the axial direction) of each blade 710. The front shroud 720 corresponds to a first shroud, and the rear shroud 730 corresponds to a second shroud.

[0032] 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.

[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 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Between the front shroud body 721 and the rear shroud 730, there are multiple spaces formed circumferentially, defined by two adjacent blades 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. Each of the centrifugal passages 760 has an inlet 761 on its radially inward opening and a discharge port 762 on its radially outward opening.

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

[0040] The introduction passage 750 is formed to extend axially from the front end 722a (tip) of the cylindrical portion 722 to the through hole 730a of the rear shroud 730. Each of the inlets 761 of the centrifugal flow path 760 is in communication with the introduction passage 750.

[0041] When the impeller 70 with such a configuration rotates, the liquid introduced into the centrifugal flow path 760 from the introduction path 750 through the introduction 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 peripheral side of the impeller 70 is introduced into the volute portion 350 and pressurized in the volute portion 350.

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

[0044] 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.

[0045] In the present 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 peripheral portion of the pump chamber 330 bulges radially outward from the storage portion 450. The outer peripheral portion of the impeller 70 that protrudes radially outward from the magnetic driven portion 80 is disposed in this bulging portion. The impeller 70 is disposed such that the rear surface of the outer peripheral portion (faces the front surface of the inner peripheral portion of the flange portion 440). The rear surface of this outer peripheral portion is the rear surface on the outer peripheral side of the rear shroud 730.

[0046] In the present embodiment, by bringing the rear surface of the peripheral wall 320 into contact with the outer peripheral side of the front surface of the flange portion 440, the storage portion 450 and the pump chamber 330 of the casing 30 are communicated with each other.

[0047] 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 screw 130 from the front side in a state where 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 portion between the casing 30 and the flange portion 440, and the watertightness of the rotating body storage chamber 510 can be ensured.

[0048] At the center of the top wall 310 of the casing 30, a suction pipe 380 connected to the upstream pipe is formed. Inside the suction pipe 380, a suction passage 381 for introducing liquid into the pump chamber 330 is formed. On the other hand, on the peripheral wall 320 of the casing 30, a discharge pipe 390 connected to the downstream pipe is formed. Inside the discharge pipe 390, a discharge passage 391 for discharging the liquid in the pump chamber 330 to the outside (such as the connected pipe) is formed.

[0049] The suction pipe 380 is protruding so as to extend forward from the center of the top wall 310. At the tip of the suction pipe 380, a suction port 381a that opens forward and sucks liquid into the suction passage 381 is formed. The suction passage 381 communicates with the flow path of the upstream pipe connected to the suction pipe 380 through the suction port 381a formed on the upstream side. Specifically, in a state where the flange portion 380b formed at the tip of the suction pipe 380 and the flange portion formed at the tip of the upstream pipe are abutted, the suction pipe 380 and the upstream pipe are connected by fixing with a fixing member such as a quick fastener.

[0050] In the present embodiment, with the impeller 70 disposed in the pump chamber 330, the suction passage 381 communicates with the introduction passage 750 of the impeller flow path 740.

[0051] Specifically, the rear end portion 380a of the suction pipe 380 is projected into the pump chamber 330, and an outlet 381b that opens rearward is formed in the projected rear end portion 380a. By inserting the outlet 381b of the rear end portion 380a into the introduction passage 750, the suction passage 381 is made to communicate with the introduction passage 750. The outlet 381b of the suction passage 381 also serves as the inlet of the introduction passage 750.

[0052] In the present embodiment, an annular groove portion 312 is formed on the outer periphery of the rear end portion 380a projected into the pump chamber 330. By inserting the front end 722a of the cylindrical portion 722 into the groove portion 312, the rotation of the impeller 70 is guided.

[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 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.

[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 the inlet 391a. The discharge port 391b opens in a direction intersecting the axial direction (in this embodiment, a perpendicular direction).

[0056] 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.

[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. 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.

[0058] 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.

[0059] 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, 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).

[0062] 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.

[0063] 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.

[0064] In this embodiment, the impeller flow path 740 is formed 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 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.

[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 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.

[0068] 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.

[0069] 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.

[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 fixing them together with a fastening member such as a quick fastener while the flange portion 380b and the flange portion formed at the tip of the upstream pipe are abutted against each other.

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

[0073] In this embodiment, a volute portion 350 is formed in a spiral shape on the outer circumference of the casing 30. The 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] When 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, is resin-molded (integrally molded) 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 (lump-shaped), which may lead to molding defects such as sink marks and warping.

[0075] According to this embodiment, a hole 315 is formed in the thick-walled portion (block-like portion) located behind the flange portion 380b of the casing 30. This makes it 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] While it is conceivable to form a hole 315 on the side of the casing 30, in this embodiment, a volute portion 350 is provided on the outer circumference of the casing 30, where the flow path expands in a spiral shape. Therefore, 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 with gradually increasing height (axial length) is formed on the casing 30, it was not possible to secure 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 could increase manufacturing and management costs due to the increased size and number of parts, and could 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 integrally with it.

[0079] In this embodiment, even when a casing 30, which is provided with a volute portion 350 that 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, holes 315 can be formed in the thick-walled portion (block-like portion).

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

[0081] By doing so, even when resin molding is performed using a pair of molds divided in the axial direction (a mold with a simple configuration), the holes 315 can be formed in the casing 30 without being obstructed by the flange portion 380b, and the casing 30 can be manufactured more easily with reduced molding defects such as sink marks and warping.

[0082] In this embodiment, a plurality of holes 315 are formed in the inner surface 311 of the top wall 310.

[0083] 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 311 is within the range of -40% to +20% of the diameter D1 (maximum radial length) of the hole 315. Furthermore, 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 311 is within the range of -40% to +20% of the diameter D1 of the hole 315.

[0084] This prevents the formation of extremely thick or thin sections in the casing 30, and prevents the opening area of ​​the hole 315 from becoming extremely large. This makes it possible to achieve both the moldability of the casing 30 and the suppression of a decrease in pump efficiency.

[0085] In this embodiment, multiple holes 315 are formed on the inner surface 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 creates multiple elongated columnar holes 315 along the circumferential direction. By making the holes 315 elongated columnar in the axial direction, the holes 315 can be formed using a pin member when molding the casing 30 using a mold, making it possible to manufacture the casing 30 at a lower cost. By making the holes 315 elongated columnar in the axial direction, turbulence in the vortex flow in each of the holes 315 can be minimized, thereby suppressing 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] In this embodiment, multiple elongated, roughly cylindrical (or roughly circular) holes 315 are formed on the inner surface 311 along the circumferential direction.

[0089] Providing such holes 315 on the inner surface 311 results in an optimal configuration from the viewpoint of moldability and pump efficiency of the casing 30. The reasons for this will be explained below.

[0090] 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 311 be plate-shaped (for example, inner and outer tubes 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 311 is a smooth plane, no unnecessary vortex flow is generated, resulting in the highest pump efficiency.

[0092] 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 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 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, multiple approximately circular holes 315 are provided along the circumferential direction, and 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 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 311, and the distance L3 between adjacent holes 315 in the circumferential direction are made to be approximately the same length. In this way, although it is not as good as a plate shape, the moldability of the resin of the casing 30 can be sufficiently ensured, and the loss of pump efficiency due to vortex flow can also be reduced.

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

[0099] (Note) The above description of embodiments discloses the following technology.

[0100] (Technology 1) The pump of Technology 1 comprises 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. A hole is formed on the surface of the casing facing the impeller, which is recessed on the side opposite to the impeller.

[0101] According to the pump of Technology 1, it is possible to suppress the formation of thickened areas in the casing, and to more reliably suppress molding defects such as sink marks and warping in the casing during resin molding. According to the pump of Technology 1, it is possible to suppress the formation of thickened areas in the casing, and to suppress molding defects such as sink marks and warping.

[0102] By forming a recessed hole on the surface of the casing facing the impeller, on the side opposite 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, such as when a pipe section with a flange 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. In particular, even when the diameter of the pipe section is large and the thickness of the area between the flange and the surface facing the impeller increases, it becomes possible to form the hole using a mold with a simple structure. As a result, casings with suppressed molding defects such as sink marks and warping can be manufactured more easily.

[0103] (Technology 2) The pump of Technology 2 has a plurality of holes, and the plurality of holes are the same as the holes described in Technology 1.

[0104] According to the pump of Technology 2, it is possible to avoid the formation of extremely thick or thin sections in the casing, and to avoid the opening area of ​​the holes becoming extremely large. Therefore, it is possible to achieve both ensuring the moldability of the casing and suppressing the decrease in pump efficiency.

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

[0106] According to the pump of Technology 3, it is possible to avoid the formation of extremely thick or thin sections in the casing, and to avoid the opening area of ​​the holes becoming extremely large. Therefore, it is possible to achieve both ensuring the moldability of the casing and suppressing the decrease in pump efficiency.

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

[0108] According to the pump of Technology 4, multiple columnar holes can be formed 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 suppressing a decrease in pump efficiency. When forming the casing using a mold, the holes can be formed using pin members, allowing for the manufacture of the casing at a lower cost.

[0109] (Technology 5) The pump of Technology 5 has the configuration of any of Technology 1 to Technology 4, plus the hole portion is approximately circular.

[0110] According to the pump of technology 5, a hole can be formed using an existing pin.

[0111] [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.

[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. It is also possible to combine the components described in the above embodiments and their variations to create new embodiments.

[0113] In the above embodiment and its modifications, the hole 315 is shown as being approximately cylindrical (approximately circular). However, the hole 315 can be made into various shapes, such as approximately rectangular prism (approximately square). The back side of the hole can also be made into an approximately hemispherical surface.

[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 more reliably suppress the occurrence of molding defects in the casing. 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 311a Inner end face 311b Outer end face 312 Groove 315 Hole 315a Inner end face 315b Outer end face 320 Peripheral wall 321 Inner surface 324 Tongue 330 Pump chamber 340 Impeller housing chamber 350 Volute section 350a Starting point 350b End point 370 Front shaft fixing section 371 Projection 372 Bearing section 373 Support rib 380 Suction pipe 380a Rear end section 380b Flange section 381 Suction passage 381a Suction 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 (inlet mouth section) 722a Front end (tip) 722b Rear end 723 Inner circumference end 724 Outer circumference end 725 Rear surface 730 Rear shroud (second shroud) 730a Through hole 731 Inner circumference end 732 Outer circumference end 733 Front 740 Impeller flow path 750 Inlet path 760 Centrifugal flow path 761 Inlet 762 Outlet 80 Magnetic 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 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, the hole being recessed on the side opposite to the impeller.

2. The pump according to claim 1, having a plurality of holes, wherein the plurality of holes are the holes.

3. The pump according to claim 1 or claim 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.

4. The pump according to claim 2, wherein 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, and the plurality of holes are formed on the opposing surfaces.

5. The pump according to claim 1 or claim 2, wherein the hole is substantially circular.

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