Pump device

Abstract

The invention provides a pump device which suppresses reduction of shape accuracy of a rotor when a driving magnet is fixed through hot riveting and achieves miniaturization of the rotor in the axial direction. A rotor (4) of a pump device is provided with: a rotor member (40) provided with a first cylindrical section (41) extending in the axial direction; and a drive magnet (8) that surrounds the outer periphery of the first cylindrical section and holds the radial bearing (11) inside the first cylindrical section. The drive magnet is provided with: a second cylindrical section (81) extending in the axial direction; and an annular rib (82) protruding radially inward from the other end of the second cylindrical section in the axial direction. The rotor member is provided with: a seat portion (42) protruding radially outward from the first cylindrical portion and supporting an end portion of the second cylindrical portion on one side in the axial direction; and a caulking section (43) that expands radially outward from the end of the other side of the first cylindrical section in the axial direction and overlaps the annular rib (82) from the other side of the first cylindrical section in the axial direction.

Description

Technical Field

[0001] The present invention relates to a pump device including a rotor that rotates integrally with an impeller portion. Background Art

[0002] Patent document 1 describes a pump device that uses a motor to rotate an impeller portion disposed in a pump chamber. The motor includes a rotor that rotates integrally with the impeller portion. The rotor includes a cylindrical portion that holds a cylindrical radial bearing inside, and a cylindrical driving magnet is fixed to the outer circumference of the cylindrical portion. The driving magnet is held between a seat portion that extends radially outward from the cylindrical portion and a rivet portion formed at the front end of the cylindrical portion.

[0003] The rotor is rotatably supported on a fixed shaft by radial bearings. When the rotor rotates, the radial bearings become hot due to friction, etc., and the driving magnets also become hot due to the heat, so that the life of the components is reduced or the magnetic properties of the driving magnets are reduced, which becomes a problem. In the pump device of Patent Document 1, the driving magnets are cooled by the fluid in the pump chamber flowing in the gap between the driving magnets and the cylindrical portion of the rotor. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-183753 Summary of the invention

[0005] In a rotor having a structure in which a driving magnet is held between a seat provided in a cylindrical portion and a caulking portion, the end face of the driving magnet is covered by the caulking portion. When the radial thickness of the driving magnet is thin, the radial width of the end face of the driving magnet is narrow. Therefore, the caulking portion is exposed to the outer periphery of the driving magnet, generating burrs, and the shape accuracy of the rotor may be reduced.

[0006] In addition, in the rotor, the radial bearing held inside the cylindrical portion is pressed against a bearing component such as a washer in the axial direction by the magnetic attraction force generated by the driving magnet. The driving magnet needs to have a size (volume) that can generate the magnetic attraction force required to press the radial bearing against the bearing component. Therefore, the axial dimension of the driving magnet is long, and the axial dimension of the rotor is long.

[0007] Furthermore, when the fluid in the pump chamber is caused to flow into the gap between the cylindrical portion of the rotor and the driving magnet to cool the radial bearing and the driving magnet, it is desirable to ensure a sufficient flow rate in order to enhance the cooling effect.

[0008] In view of the above problems, an object of the present invention is to suppress a decrease in the shape accuracy of a rotor when a driving magnet is fixed by heat caulking and to achieve miniaturization of the rotor in the axial direction.

[0009] Furthermore, another object of the present invention is to form a flow path with a large flow rate inside the driving magnet.

[0010] In order to solve the above-mentioned problems, the pump device of the present invention comprises: a motor, which comprises a rotor and a stator surrounding the outer peripheral side of the rotor; and an impeller part, when the direction along the rotation axis of the rotor is set as the axial direction, the impeller part is arranged in a pump chamber provided on one side of the axial direction relative to the stator, and rotates integrally with the rotor, the rotor comprising: a rotor component, which comprises a first cylindrical portion extending in the axial direction; and a driving magnet, which surrounds the outer periphery of the first cylindrical portion, and a radial bearing is held inside the first cylindrical portion, the driving magnet comprising: a second cylindrical portion, which surrounds the outer periphery of the first cylindrical portion and extends in the axial direction; and an annular rib, which protrudes radially inward from the end of the second cylindrical portion on the other side in the axial direction, the rotor component comprising: a seat portion, which protrudes radially outward from the first cylindrical portion and supports the end of the second cylindrical portion on one side in the axial direction; and a caulking portion, which extends radially outward from the end of the first cylindrical portion on the other side in the axial direction and overlaps with the annular rib from the other side in the axial direction.

[0011] According to the present invention, the driving magnet is held between the seat portion and the riveting portion of the first cylindrical portion provided on the rotor component. The driving magnet is provided with an annular rib protruding radially inward at the end portion located on the front end side (the side provided with the riveting portion) of the first cylindrical portion. In this way, by not forming the driving magnet into a simple cylindrical shape but providing a portion (annular rib) protruding toward the inner circumference, the volume can be ensured even when the length in the axial direction is shortened, and the necessary magnetic attraction force can be ensured. In addition, since the annular rib is provided at the end portion on the side where the riveting portion is provided, the radial width of the end face subjected to the riveting portion is large. Therefore, the possibility of the riveting portion being exposed radially outward from the driving magnet is small, and thus the reduction in the shape accuracy of the rotor caused by hot riveting can be suppressed.

[0012] In the present invention, it is preferred that there is a radial gap between the first cylindrical portion and the second cylindrical portion, and the gap functions as a flow groove for the fluid in the pump chamber to flow, and the other side of the flow groove in the axial direction is blocked by the annular rib and the riveted portion. In this way, the flow groove becomes a depth (radial dimension) corresponding to the protruding dimension of the annular rib, so that the volume of the flow groove can be ensured, and a large amount of fluid can flow between the driving magnet and the first cylindrical portion. Therefore, the cooling effect of the radial bearing maintained on the inner side of the first cylindrical portion and the cooling effect of the driving magnet can be improved. Therefore, the reduction in the life of the components caused by high temperature and the reduction in the magnetic properties of the driving magnet can be suppressed.

[0013] In the present invention, it is preferred that a plurality of magnet side ribs protruding radially inward and extending along the axial direction are circumferentially arranged on the inner circumferential surface of the second cylindrical portion, and the gaps between the ribs adjacent in the circumferential direction function as the flow path grooves. In this way, since the first cylindrical portion can be embedded into the inner side of the magnet side ribs arranged radially, a flow path groove with a large volume can be ensured, and the driving magnet can be assembled with high precision. In addition, since the second cylindrical portion can be strengthened by the magnet side ribs, the strength of the driving magnet can be improved.

[0014] In the present invention, it is preferable that the end of the magnet side rib on the other side in the axial direction is connected to the annular rib. In this way, the second cylindrical portion and the annular rib are connected via the magnet side rib, thereby improving the strength of the driving magnet.

[0015] In the present invention, it is preferred that a plurality of rotor component side ribs protruding radially outward and extending in the axial direction are circumferentially arranged on the outer circumferential surface of the first cylindrical portion, and the front end surface of the magnet side rib abuts against the front end surface of the rotor component side rib, thereby dividing the flow path groove in the circumferential direction. In this way, by forming ribs not only on the driving magnet but also on the rotor component, the depth (radial width) of the flow path groove can be further increased. Therefore, the volume of the flow path groove can be ensured.

[0016] In the present invention, an inlet communicating with the flow path groove is preferably provided between the seat portion and the second cylindrical portion, so that the fluid in the pump chamber can flow into the flow path groove through the gap on the outer peripheral side of the driving magnet.

[0017] In the present invention, it is preferred that the flow path groove comprises: a first groove portion extending in the axial direction; a second groove portion extending in the axial direction on the rear side of the first groove portion in the rotation direction of the rotor; and a third groove portion extending in the circumferential direction and connecting the ends of the first groove portion and the second groove portion on the other side of the axial direction, and the inlet is connected to the first groove portion. In this way, the flow path groove becomes a shape (U-shaped) that connects the first groove portion and the second groove portion extending in the axial direction through the third groove portion to be folded back once in the axial direction. Thus, compared with the case where only a straight flow path is provided, the area in contact with the fluid can be expanded, and the cooling effect can be improved. In addition, when the rotor rotates, the fluid flows to the rear side of the rotation direction due to the inertial force, so the inlet side becomes negative pressure, and the fluid in the pump chamber continues to flow in. Therefore, the cooling effect can be improved.

[0018] In the present invention, it is preferred that the seat is provided with a recessed portion that is recessed toward one side in the axial direction, and the inlet is a gap between the bottom surface of the recessed portion and the end surface of the second cylindrical portion on one side in the axial direction. In this way, a flow path that connects the outer circumference and the inner circumference of the driving magnet can be formed with a simple structure without providing a through hole in the component.

[0019] In the present invention, it is preferred that the first convex portion protruding from the bottom surface of the recess is engaged with the first concave portion provided on the end surface of the driving magnet, and the portions on both sides of the circumferential direction of the first convex portion in the recess form the two inlets. In this way, a rotation-stopping portion for preventing the driving magnet from rotating relative to the rotor component can be provided. In addition, since the angular position of the inlet relative to the driving magnet can be made consistent, the inlet can be provided at an appropriate angular position.

[0020] In the present invention, it is preferred that the impeller portion comprises: a flange portion, which is arranged at the end of one side of the axial direction of the rotor component; and an impeller, which is fixed to the flange portion from one side of the axial direction, and the first cylindrical portion comprises: a connecting portion, which extends along the axial direction between the flange portion and the seat portion; and a magnet retaining portion, which is embedded in the inner side of the driving magnet, the radial bearing is retained on the inner side of the magnet retaining portion, and the inner side of the connecting portion becomes a first space where the fluid of the pump chamber flows through the through hole that radially penetrates the connecting portion, and the first space is connected to the bearing cooling flow path that penetrates the magnet retaining portion along the axial direction. In this way, the fluid of the pump chamber can also flow into the bearing cooling flow path from a position different from the outer peripheral side of the driving magnet (the first space). Therefore, the cooling effect can be improved.

[0021] According to the present invention, even when the length of the driving magnet in the axial direction is shortened, the volume can be ensured and the necessary magnetic attraction force can be ensured. In addition, since an annular rib is provided at the end of the side where the rivet portion is provided, the radial width of the end face on the side receiving the rivet portion is large. Therefore, the possibility of the rivet portion being exposed radially outward from the driving magnet is small, so the reduction in the shape accuracy of the rotor caused by hot rivet pressing can be suppressed.

[0022] Furthermore, in the present invention, since a flow path groove having a depth corresponding to the protruding size of the annular rib can be ensured on the inner side of the driving magnet, a flow path with a large flow rate can be formed. Therefore, the cooling effect of the radial bearing held on the inner side of the first cylindrical portion and the cooling effect of the driving magnet can be improved. Therefore, the reduction in the life of the components and the reduction in the magnetic properties of the driving magnet caused by high temperature can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a perspective view of the appearance of a pump device to which the present invention is applied. Figure 2 Yes Figure 1 The pump device is shown in a sectional view through a plane containing the axis of rotation. Figure 3 is a side view of the rotor. Figure 4 This is an exploded perspective view of the rotor and radial bearing viewed from one side in the axial direction. Figure 5 This is an exploded perspective view of the rotor and radial bearing viewed from the other side in the axial direction. Figure 6 It is a cutaway perspective view of the rotor components. Figure 7 This is a partial cross-sectional view of the rotor, radial bearing, and support shaft cut along a plane containing the axis of rotation. Figure 8 This is a sectional stereogram of the rotor, radial bearing and support shaft cut by a plane perpendicular to the axis of rotation (in Figure 7 AA position section). Fig. 9 This is a sectional stereogram of the rotor, radial bearing and support shaft cut by a plane perpendicular to the axis of rotation (in Figure 7 BB position section). DETAILED DESCRIPTION

[0024] Hereinafter, the pump device 1 according to the embodiment of the present invention will be described with reference to the accompanying drawings. In this specification, the axial direction refers to the direction in which the rotation axis L of the motor 10 extends. One side of the axial direction is set as L1, and the other side of the axial direction is set as L2. The radial direction of the radial inside and the radial outside refers to the radial direction centered on the rotation axis L. The circumferential direction refers to the rotation direction centered on the rotation axis L.

[0025] (Overall structure) Figure 1 This is a perspective view of the appearance of a pump device 1 to which the present invention is applied. Figure 2 Yes Figure 1 The pump device 1 shown is a cross-sectional view cut along a plane containing the rotation axis L. Figure 1 , Figure 2 As shown, the pump device 1 includes: a housing 2 having a suction pipe 21 and a discharge pipe 22 extending to one side L1 in the axial direction; a motor 10 disposed on the other side L2 in the axial direction relative to the housing 2; and an impeller portion 25 disposed in a pump chamber 20 inside the housing 2. The impeller portion 25 is driven by the motor 10 to rotate around the rotation axis L. In the pump device 1 of the present embodiment, the fluid flowing in the pump chamber 20 is a liquid. The pump device 1 is used under conditions where the ambient temperature or the fluid temperature is easily changed, for example.

[0026] The motor 10 includes: a stator 3 in an annular shape; a rotor 4 disposed inside the stator 3; a support shaft 5 supporting the rotor 4 so as to be rotatable; and a resin housing 6 covering the stator 3. The support shaft 5 is made of metal or ceramic. The impeller 25 rotates integrally with the rotor 4. Figure 2 As shown, in the pump device 1 , the impeller portion 25 and the pump chamber 20 are provided on one side L1 in the axial direction with respect to the stator 3 .

[0027] like Figure 2 As shown, the pump chamber 20 is provided between the housing 2 and the casing 6. The housing 2 includes: an upper wall 23 located on one side L1 of the axial direction of the pump chamber 20; and a side wall 29 surrounding the outer periphery of the pump chamber 20 and extending in the circumferential direction. Figure 1 As shown, the suction pipe 21 extends in the axial direction at the radial center of the housing 2. The discharge pipe 22 extends from the side wall 29 in a direction orthogonal to the rotation axis L of the motor 10.

[0028] like Figure 2 As shown, the stator 3 includes: a stator core 31; an insulator 32, which overlaps with the stator core 31 from one side L1 in the axial direction; an insulator 33, which overlaps with the stator core 31 from the other side L2 in the axial direction; and a plurality of coils 35, which are wound around a plurality of salient poles provided on the stator core 31 via the insulators 32 and 33. The motor 10 is a three-phase motor. Therefore, the plurality of coils 35 include a U-phase coil, a V-phase coil, and a W-phase coil.

[0029] The rotor 4 includes a rotor component 40 made of resin. The rotor component 40 includes: a first cylindrical portion 41 extending in the axial direction; and a flange portion 45 formed at an end portion of one side L1 of the first cylindrical portion 41 in the axial direction. The first cylindrical portion 41 extends from the radial inner side of the stator 3 toward the pump chamber 20 and opens in the pump chamber 20. A cylindrical driving magnet 8 is retained on the outer peripheral surface of the first cylindrical portion 41. The driving magnet 8 is opposite to the stator 3 on the radial inner side. The driving magnet 8 is composed of, for example, a neodymium bond magnet.

[0030] The impeller 24 is connected to the flange portion 45 of the rotor component 40 from one side L1 in the axial direction. In the present embodiment, the impeller portion 25 connected to the first cylindrical portion 41 of the rotor component 40 is constituted by the flange portion 45 and the impeller 24. The impeller 24 includes: a circular plate portion 26 opposite to the flange portion 45 in the axial direction; and a plurality of blade portions 261 protruding from the circular plate portion 26 to the other side L2 in the axial direction. The impeller 24 is fixed to the flange portion 45 via the blade portions 261. A central hole 260 is formed in the center of the circular plate portion 26. The circular plate portion 26 is inclined toward the flange portion 45 side as it moves toward the radial outer side. The plurality of blade portions 261 are arranged at equal angles. Each blade portion 261 is curved into an arc shape from the periphery of the central hole 260 and extends toward the radial outer side.

[0031] In the rotor component 40, a cylindrical radial bearing 11 is held radially inside the first cylindrical portion 41. The rotor 4 is rotatably supported on the support shaft 5 by the radial bearing 11. The end portion of the support shaft 5 on the other side L2 in the axial direction is held in the shaft hole 65 formed in the bottom wall 63 of the housing 6. The housing 2 has three support portions 27 extending from the inner circumferential surface of the suction pipe 21 toward the motor 10. A cylindrical portion 28 opened to the other side L2 in the axial direction is formed on the support portion 27, and the end portion of the support shaft 5 on one side L1 in the axial direction is held in the cylindrical portion 28.

[0032] An annular thrust bearing 12 is installed at the end of one side L1 of the axial direction of the support shaft 5, and the thrust bearing 12 is arranged between the radial bearing 11 and the end surface of the cylinder 28. The radial bearing 11 is pushed onto the thrust bearing 12 from the other side L2 of the axial direction by the magnetic attraction force of the driving magnet 8. Here, the end of the other side L2 of the support shaft 5 and at least a part of the shaft hole 65 are in a D-shaped cross section. In addition, the end of one side L1 of the support shaft 5 and the hole of the thrust bearing 12 are in a D-shaped cross section. Therefore, the support shaft 5 and the thrust bearing 12 are prevented from rotating relative to the housing 6.

[0033] The housing 6 is a resin sealing component 60 that covers the stator 3 from both sides in the radial direction and both sides in the axial direction. The resin sealing component 60 is made of polyphenylene sulfide (PPS). The stator 3 is integrated with the resin sealing component 60 by insert molding. The housing 6 is a partition wall member, having: a first partition wall 61 opposite to the upper wall 23 on one side L1 of the axial direction covering the pump chamber 20; a second partition wall 62 between the stator 3 and the driving magnet 8; and a bottom wall 63 provided at the end of the other side L2 of the second partition wall 62. In addition, the housing 6 has a cylindrical main body 66 that covers the stator 3 from the outside in the radial direction.

[0034] like Figure 1 , Figure 2 As shown, the cover 18 is fixed to the end 64 on the other side L2 of the housing 6 in the axial direction from the other side L2 in the axial direction. Figure 2 As shown, a substrate 19 is arranged between the cover 18 and the bottom wall 63 of the housing 6, and the substrate 19 is provided with a circuit for controlling the power supply to the coil 35. A metal winding terminal 71 is connected to the substrate 19 by soldering, and the winding terminal 71 protrudes from the stator 3 through the bottom wall 63 of the housing 6 to the other side L2 in the axial direction. The housing 6 has a columnar portion 67 protruding from the bottom wall 63 to the other side L2 in the axial direction. The substrate 19 is fixed to the columnar portion 67 by screws.

[0035] like Figure 1As shown, the housing 6 includes a cylindrical connector housing 69 extending radially outward from a main body portion 66 surrounding the outer peripheral side of the stator 3. A connector terminal having one end connected to the substrate 19 is arranged inside the connector housing 69. When the connector is connected to the connector housing 69, a drive current generated by a circuit mounted on the substrate 19 is supplied to each coil 35 through the winding terminal 71. As a result, the rotor 4 rotates around the rotation axis L of the motor 10. As a result, the impeller portion 25 rotates in the pump chamber 20, and the interior of the pump chamber 20 becomes a negative pressure, so that the fluid is sucked into the pump chamber 20 from the suction pipe 21 and discharged from the discharge pipe 22.

[0036] (Drive magnet and radial bearing holding structure) Figure 3 is a side view of the rotor. Figure 4 It is an exploded perspective view of the rotor 4 and the radial bearing 11 as viewed from one side L1 in the axial direction. Figure 5 It is an exploded perspective view of the rotor 4 and the radial bearing 11 as viewed from the other side L2 in the axial direction. Figure 6 It is a cross-sectional perspective view of the rotor member 40 . Figure 7 This is a partial cross-sectional view of the rotor 4, radial bearing 11, and support shaft 5 cut along a plane including the rotation axis. Figure 8 and Fig. 9 This is a cross-sectional perspective view of the rotor 4 , the radial bearing 11 , and the support shaft 5 cut along a plane perpendicular to the rotation axis L. Figure 8 is Figure 7 A partial cross-sectional view cut at the AA position. Fig. 9 is Figure 7 A partial cross-sectional view taken at the BB position.

[0037] like Figure 2 , Figure 5 As shown, the rotor component 40 has an annular seat portion 42 protruding radially outward from the first cylindrical portion 41 at a position away from the flange portion 45 toward the other side L2 in the axial direction. The first cylindrical portion 41 has a magnet retaining portion 410 extending from the seat portion 42 toward the other side L2 in the axial direction. The magnet retaining portion 410 is embedded in the inner side of the driving magnet 8 to retain the driving magnet 8. At this time, the seat portion 42 supports the end of the one side L1 in the axial direction of the driving magnet 8. As shown in FIG. Figure 2 , Figure 3 , Figure 7 As shown, a caulking portion 43 is formed at the end of the other side L2 of the magnet holding portion 410 in the axial direction so as to overlap with the end of the other side L2 of the driving magnet 8 from the other side L2 in the axial direction. Figure 4 , Figure 5 , Figure 7The shape of the rotor member 40 shown is the shape before the front end portion 411 of the other side L2 of the magnet holding portion 410 is crushed, and is the shape before the caulking portion 43 is formed.

[0038] like Figure 4 , Figure 5 As shown, the radial bearing 11 includes a cylindrical portion 110 extending in the axial direction and a large diameter portion 111 provided at one axial end L1 of the cylindrical portion 110. The rotor member 40 is a resin molded product, and the radial bearing 11 is fixed to the magnet holding portion 410 by insert molding.

[0039] like Figure 2 , Figure 7 As shown, the driving magnet 8 includes: a second cylindrical portion 81 extending in the axial direction; and an annular rib 82 protruding radially inward from the end portion of the second cylindrical portion 81 on the other side L2 in the axial direction. The second cylindrical portion 81 and the annular rib 82 are connected in a manner such that the entire cross-sectional shape is an L font. The rotor component 40 and the driving magnet 8 are assembled in the following manner: the magnet holding portion 410 of the rotor component 40 is inserted into the inner side of the second cylindrical portion 81 of the driving magnet 8, and the front end portion 411 of the magnet holding portion 410 is embedded in the inner side of the annular rib 82.

[0040] like Figure 4 , Figure 8 , Fig. 9 As shown in FIG. 1 , the driving magnet 8 has a plurality of magnet side ribs 83 protruding radially inward from the inner circumference of the second cylindrical portion 81. The plurality of magnet side ribs 83 are arranged circumferentially at a certain angle interval. In this embodiment, the magnet side ribs 83 are arranged at six locations at 60 degree intervals. Figure 4 , Figure 5 As shown, the end portion of the magnet-side rib 83 on the other side L2 in the axial direction is connected to the annular rib 82. The magnet holding portion 410 is embedded inside the six magnet-side ribs 83 arranged radially.

[0041] like Figure 4 As shown, on the rotor component 40, notch portions 420 formed by cutting the outer peripheral edge of the seat portion 42 toward the inner peripheral side are provided at multiple positions separated in the circumferential direction. A recessed portion 421 extending in the radial direction is provided at the circumferential center of each notch portion 420. A first convex portion 422 protruding toward the other side L2 in the axial direction is provided at the circumferential center of each recessed portion 421. The first convex portion 422 is connected to the outer peripheral surface of the magnet holding portion 410 and extends to the outer edge of the seat portion 42. The height of the first convex portion 422 in the axial direction is greater than the depth of the recessed portion 421 in the axial direction. In the present embodiment, the notch portions 420 and the recessed portions 421 are provided at three locations at intervals of 120 degrees.

[0042] like Figure 4As shown, the driving magnet 8 has three first recesses 84 and three gate marks 85 alternately arranged at equal angles in the circumferential direction on the end surface of the second cylindrical portion 81 on one side L1 in the axial direction. When the driving magnet 8 is fixed to the magnet holding portion 410, the end surface of the second cylindrical portion 81 on one side L1 in the axial direction is brought into contact with the seat portion 42 from the other side L2 in the axial direction. At this time, the plurality of first protrusions 422 are respectively in contact with the first recesses 84 (see FIG. 1 ) formed on the end surface of the second cylindrical portion 81 on one side L1 in the axial direction. Figure 4 ) are engaged to form a rotation stop portion E. Thus, the driving magnet 8 is prevented from rotating relative to the rotor member 40.

[0043] When the driving magnet 8 is assembled to the outer periphery of the magnet holding portion 410, the front end portion 411 (see Figure 4 , Figure 5 ) protrudes from the end surface of the other side L2 of the driving magnet 8. When manufacturing the rotor 4, the caulking portion 43 is formed by flattening the front end portion 411 of the magnet holding portion 410 (see Figure 3 , Figure 7 , Figure 8 ). The caulking portion 43 overlaps the inner peripheral edge of the annular rib 82 of the driving magnet 8 over the entire circumference from the other side L2 in the axial direction.

[0044] In the present embodiment, the number of poles of the driving magnet 8 is 6, and the number of slots of the stator 3 is 9. Therefore, on the outer peripheral surface of the driving magnet 8, the N pole and the S pole are magnetized three poles alternately. As described above, the driving magnet 8 has magnet side ribs 83 at six locations. The position where the magnet side ribs 83 are formed can be, for example, the position where the magnetic flux density is the largest, that is, the circumferential center of each magnetic pole.

[0045] (Flow path for cooling) like Figure 2 , Figure 7 As shown in FIG. 1 , the rotor 4 of this embodiment is provided with a radial gap between the magnet holding portion 410 of the rotor member 40 and the driving magnet 8. The gap functions as a flow path F for the fluid flowing in the pump chamber 20. The flow path F is connected to the pump chamber 20 via the inlet 44 (see FIG. 1 ) provided between the second cylindrical portion 81 of the driving magnet 8 and the seat portion 42 of the rotor member 40. Figure 3 ), and the gap G1 between the driving magnet 8 and the second partition wall 62 of the housing 6 (refer to Figure 2 The fluid passing through the pump chamber 20 flows in the flow path groove F, the driving magnet 8 and the magnet holding portion 410 are cooled, and the radial bearing 11 is cooled via the magnet holding portion 410.

[0046] like Figure 3As shown, the inlet 44 is provided between the second cylindrical portion 81 of the driving magnet 8 and the seat portion 42, and is open to the radially outer side. As described above, the seat portion 42 is provided with a recessed portion 421 recessed toward one side L1 in the axial direction, and the inlet 44 is formed by the end surface of the second cylindrical portion 81 on one side L1 in the axial direction and the recessed portion 421. The inlet 44 is provided at one location on each side in the circumferential direction of the stop portion E, which is a stop portion where the first convex portion 422 of the rotor component 40 and the first concave portion 84 of the driving magnet 8 are engaged.

[0047] like Figure 4 , Figure 5 As shown, the rotor component 40 includes a plurality of rotor component side ribs 50 formed on the outer peripheral surface of the magnet holding portion 410 of the first cylindrical portion 41. The rotor component side ribs 50 extend in the axial direction with a certain width. The end of one side L1 of the rotor component side rib 50 in the axial direction is connected to the seat portion 42. In this embodiment, as the rotor component side rib 50, there are two types of ribs, a first rib 51 extending to the front end portion 411 of the other side L2 of the magnet holding portion 410 and a second rib 52 having a shorter length in the axial direction than the first rib 51.

[0048] like Figure 8 , Fig. 9 As shown, on the outer peripheral surface of the magnet holding portion 410, rotor component side ribs 50 are provided at six locations at intervals of 60 degrees. The rotor component 40 and the driving magnet 8 are assembled into a state in which the angular positions of the rotor component side ribs 50 and the magnet side ribs 83 are consistent by fitting the above-mentioned anti-rotation portion E. The circumferential width of the rotor component side ribs 50 is larger than the circumferential width of the magnet side ribs 83. The gap between the magnet holding portion 410 and the driving magnet 8 is divided in the circumferential direction by the front end surface of the rotor component side ribs 50 abutting against the front end surface of the magnet side ribs 83. Thus, a flow path groove F extending in the axial direction is formed.

[0049] Figure 4 , Figure 5 , Figure 8 , Fig. 9 The R1 direction shown is the front side of the rotation direction of the rotor 4, and the R2 direction is the rear side of the rotation direction of the rotor 4. Figure 5 As shown in FIG. 1 , the flow path groove F includes: a first groove portion F1 extending in the axial direction; a second groove portion F2 extending in the axial direction at the rear side R2 of the first groove portion F1 in the rotation direction of the rotor 4; and a third groove portion F3 extending in the circumferential direction and connecting the ends of the first groove portion F1 and the second groove portion F2 on the other side L2 in the axial direction. That is, a portion of the flow path groove F forms a substantially U-shaped groove that is folded back once in the axial direction.

[0050] like Figure 5As shown, the third groove F3 extends circumferentially on the other side L2 of the axial direction of the second rib 52. The magnet side rib 83 abutting against the second rib 52 extends further to the other side L2 than the second rib 52. Therefore, a gap (see FIG. 1 ) serving as the third groove F3 is formed between the front end of the magnet side rib 83 abutting against the second rib 52 and the outer peripheral surface of the magnet holding portion 410. Fig. 9 ).

[0051] like Figure 5 As shown, the recessed portion 421 forming the inlet 44 is set at an angle position consistent with the first groove portion F1. Among the first groove portion F1, the second groove portion F2 and the third groove portion F3 that form a U-shaped flow path as a whole, the third groove portion F3 and the second groove portion F2 are set at the rear side R2 in the rotation direction relative to the first groove portion F1 connected to the inlet 44 (recessed portion 421). Therefore, when the rotor 4 rotates in the R1 direction, due to the inertial force, the fluid in the first groove portion F1 moves in the R2 direction, flows in the third groove portion F3 and the second groove portion F2, and generates Figure 5 As a result, the first groove F1 has a negative pressure, so the fluid flows into the first groove F1 from the inlet 44. Therefore, during the rotation of the rotor 4, the fluid flows in the flow path groove F along the Figure 5 The D direction shown shows continuous flow.

[0052] The radially outer portion of the second groove portion F2 of the seat portion 42 is a flat surface that supports the drive magnet 8, so no wide opening such as the inlet 44 is formed on the radially outer side of the second groove portion F2. Therefore, the first groove portion F1, the second groove portion F2, and the third groove portion F3 that form the U-shaped flow path generate a differential pressure between the inflow side and the outflow side, so that the fluid easily flows in.

[0053] like Figure 8 As shown, six flow path grooves F divided by six rotor component side ribs 50 and magnet side ribs 83 extending in the axial direction are provided between the magnet holding portion 410 and the driving magnet 8. Here, among the six rotor component side ribs 50, four are first ribs 51 extending to the front end portion of the other side L2 of the magnet holding portion 410, and the other two are second ribs 52 whose length in the axial direction is shorter than that of the first ribs 51. The first ribs 51 and the second ribs 52 are alternately arranged in the circumferential direction. Therefore, four of the six flow path grooves F form flow paths connected in a U shape via the third groove portion F3 formed on the other side L2 of the second rib 52 as described above, and the other two form flow paths extending in a straight line from the seat portion 42 to the annular rib 82.

[0054] (Bearing cooling flow path) like Figure 6As shown, the first cylindrical portion 41 of the rotor member 40 has a connecting portion 412 extending in the axial direction between the flange portion 45 and the seat portion 42. One side L1 of the first space H on the inner side of the connecting portion 412 in the axial direction is opened at the center of the flange portion 45 and communicates with the pump chamber 20. In addition, the first space H is communicated with the pump chamber 20 via a through hole 46 that penetrates the connecting portion 412. The through hole 46 is provided at two locations on opposite sides in the radial direction. Figure 2 As shown, the end of the support shaft 5 extends into the first space H and is inserted into the cylinder 28 disposed in the first space H. A portion of the large diameter portion 111 of the radial bearing 11 is disposed in the first space H and abuts against the thrust bearing 12 .

[0055] A flow path groove 47 with an arc-shaped cross section extending in the axial direction is provided on the inner peripheral surface of the connecting portion 412. Each flow path groove 47 is connected to a bearing cooling flow path 48 that penetrates the magnet holding portion 410 in the axial direction. The flow path groove 47 and the bearing cooling flow path 48 are provided at two locations on opposite sides in the radial direction. The end portion on the other side in the axial direction of the bearing cooling flow path 48 is spaced apart from the gap G2 (see FIG. 1 ) between the bottom wall 63 of the housing 6 and the magnet holding portion 410. Figure 2 Therefore, the fluid of the pump chamber 20 that flows in from the outer peripheral side of the through hole 46 and the flange portion 45 flows through the bearing cooling flow path 48, thereby cooling the radial bearing 11 and the magnet holding portion 410.

[0056] (Main effects of this embodiment) As described above, the pump device 1 of the present embodiment includes: the motor 10 including the rotor 4 and the stator 3 surrounding the outer circumference of the rotor 4; and the impeller portion 25, which is arranged in the pump chamber 20 provided on the one side L1 in the axial direction relative to the stator 3 when the direction along the rotation axis L of the rotor 4 is defined as the axial direction, and rotates integrally with the rotor 4. The rotor 4 includes: the rotor member 40 including the first cylindrical portion 41 extending in the axial direction; and the driving magnet 8 surrounding the outer circumference of the first cylindrical portion 41 and holding the radial bearing 11 inside the first cylindrical portion 41. The driving magnet 8 includes: the second cylindrical portion 81 surrounding the outer circumference of the first cylindrical portion 41 and extending in the axial direction; and the annular rib 82 protruding radially inward from the end of the second cylindrical portion 81 on the other side L2 in the axial direction. The rotor component 40 includes: a seat portion 42, which protrudes radially outward from the first cylindrical portion 41 to support the end of one side L1 of the axial direction of the second cylindrical portion 81; and a rivet portion 43, which extends radially outward from the end of the other side L2 of the axial direction of the first cylindrical portion 41 and overlaps with the annular rib 82 from the other side L2 of the axial direction.

[0057] According to the present embodiment, the driving magnet 8 is held between the seat 42 of the first cylindrical portion 41 provided in the rotor component 40 and the rivet portion 43. The driving magnet 8 is provided with an annular rib 82 protruding radially inward at the end portion located on the front end side (the side provided with the rivet portion 43) of the first cylindrical portion 41. In this way, by not forming the driving magnet 8 into a simple cylindrical shape, but providing a portion (annular rib 82) protruding toward the inner circumference, the volume can be ensured even when the length in the axial direction is shortened, and the necessary magnetic attraction force can be ensured. In addition, since the annular rib 82 is provided at the end portion of the side where the rivet portion 43 is provided, the radial width of the end face that bears the rivet portion 43 is large. Therefore, the possibility of the rivet portion 43 being exposed radially outward from the driving magnet 8 is small, so that the reduction in the shape accuracy of the rotor 4 caused by hot riveting can be suppressed.

[0058] In the present embodiment, there is a radial gap between the first cylindrical portion 41 and the second cylindrical portion 81, and the gap functions as a flow groove F for the flow of fluid in the pump chamber 20. The other side L2 of the flow groove F in the axial direction is blocked by the annular rib 82 and the rivet portion 43. With such a structure, the flow groove F becomes a depth (radial dimension) corresponding to the protruding dimension of the annular rib 82, so that the volume of the flow groove F can be ensured, and a large amount of fluid can flow between the driving magnet 8 and the first cylindrical portion 41. Therefore, the cooling effect of the radial bearing 11 maintained on the inner side of the first cylindrical portion 41 and the cooling effect of the driving magnet 8 can be improved. Therefore, the reduction in the life of the components caused by high temperature and the reduction in the magnetic properties of the driving magnet 8 can be suppressed.

[0059] In the present embodiment, a plurality of magnet side ribs 83 protruding radially inward and extending in the axial direction are arranged circumferentially on the inner circumferential surface of the second cylindrical portion 81, and the gaps between the magnet side ribs 83 adjacent to each other in the circumferential direction function as flow grooves F. With such a structure, the first cylindrical portion 41 can be embedded inside the radially arranged magnet side ribs 83, so that a flow groove F with a large volume can be ensured, and the driving magnet 8 can be assembled with high precision. In addition, since the second cylindrical portion 81 can be reinforced by the magnet side ribs 83, the strength of the driving magnet 8 can be improved.

[0060] In this embodiment, the end portion of the magnet-side rib 83 on the other axial side L2 is connected to the annular rib 82. Thus, the second cylindrical portion 81 and the annular rib 82 are connected via the magnet-side rib 83, thereby improving the strength of the driving magnet 8.

[0061] In this embodiment, a plurality of rotor component side ribs 50 are arranged along the circumferential direction on the outer circumferential surface of the first cylindrical portion 41, protruding radially outward and extending along the axial direction. The front end surface of the magnet side rib 83 is brought into contact with the front end surface of the rotor component side rib 50, thereby dividing the flow path F in the circumferential direction. In this way, ribs are formed not only on the driving magnet 8 but also on the rotor component 40, thereby further increasing the depth (radial dimension) of the flow path F. Therefore, the volume of the flow path F can be ensured.

[0062] In this embodiment, the inlet 44 communicating with the flow groove F is provided between the seat portion 42 and the second cylindrical portion 81 , so that the fluid in the pump chamber 20 can flow into the flow groove F through the gap G1 on the outer peripheral side of the driving magnet 8 .

[0063] In the present embodiment, the flow path groove F comprises: a first groove portion F1 extending in the axial direction; a second groove portion F2 extending in the axial direction on the rear side (R2 direction) of the rotation direction of the rotor 4 relative to the first groove portion F1; and a third groove portion F3 extending in the circumferential direction and connecting the ends of the first groove portion F1 and the second groove portion F2 on the other side L2 in the axial direction. The inlet 44 is connected to the first groove portion F1. That is, the flow path groove F of the present embodiment is a shape (U-shaped) that is formed by connecting the first groove portion F1 and the second groove portion F2 extending in the axial direction through the third groove portion F3 to be folded once in the axial direction. Thus, compared with the case where only a linear flow path is provided, the area in contact with the fluid can be expanded, so the cooling effect can be improved. In addition, when the rotor 4 rotates, the fluid flows to the rear side (R2 direction) in the rotation direction due to the inertial force, so the inlet 44 side becomes negative pressure, and the fluid in the pump chamber 20 continues to flow in. Therefore, the cooling effect can be improved.

[0064] In the present embodiment, a recessed portion 421 recessed toward one side L1 in the axial direction is provided on the seat portion 42, and the inlet 44 is a gap between the bottom surface of the recessed portion 421 and the end surface of the one side L1 in the axial direction of the second cylindrical portion 81. Therefore, the inlet 44 that connects the outer circumference and the inner circumference of the driving magnet 8 can be formed with a simple structure without providing a through hole in the component.

[0065] In the present embodiment, the first convex portion 422 protruding from the bottom surface of the concave portion 421 is fitted with the first concave portion 84 provided on the end surface of the driving magnet 8, and the portions on both sides of the first convex portion 422 in the concave portion 421 in the circumferential direction form two inlet ports 44. In this way, a rotation stop portion E for preventing the driving magnet 8 from rotating relative to the rotor member 40 can be provided. In addition, since the angular position of the inlet port 44 relative to the driving magnet 8 can be made consistent, the inlet port 44 can be provided at an appropriate angular position.

[0066] In the present embodiment, the impeller portion 25 includes: a flange portion 45 provided at an end portion of one side L1 of the rotor member 40 in the axial direction; and an impeller 24 fixed to the flange portion 45 from one side L1 in the axial direction. The first cylindrical portion 41 includes: a connection portion 412 extending in the axial direction between the flange portion 45 and the seat portion 42; and a magnet holding portion 410 embedded in the inner side of the driving magnet 8, and the radial bearing 11 is held in the inner side of the magnet holding portion 410. The inner side of the connection portion 412 becomes a first space H in which the fluid of the pump chamber 20 flows through the through hole 46 penetrating the connection portion 412 in the radial direction, and the first space H is connected to the bearing cooling flow path 48 penetrating the magnet holding portion 410 in the axial direction. By providing such a structure, the fluid of the pump chamber 20 can also flow into the bearing cooling flow path 48 from a position different from the gap G1 on the outer peripheral side of the driving magnet 8 (the center of the flange portion 45). Therefore, the cooling effect can be improved.

[0067] (Other methods) The present invention includes the same method as the above-mentioned rotor 4 except that the flow path groove F is not provided between the driving magnet 8 and the magnet holding part 410. That is, the present invention includes a structure in which the outer peripheral surface of the magnet holding part 410 and the inner peripheral surface of the second cylindrical part 81 of the driving magnet 8 are in close contact with each other without generating a gap.

[0068] The present invention can take the following structures. (1) A pump device comprising: A motor including a rotor and a stator surrounding an outer circumference of the rotor; an impeller portion, which is arranged in a pump chamber provided on one side of the axial direction relative to the stator when the direction along the rotation axis of the rotor is defined as an axial direction, and rotates integrally with the rotor, The rotor includes: a rotor member including a first cylindrical portion extending in the axial direction; and a driving magnet surrounding an outer circumference of the first cylindrical portion, wherein a radial bearing is held inside the first cylindrical portion. The driving magnet comprises: a second cylindrical portion surrounding the outer periphery of the first cylindrical portion and extending in the axial direction; and an annular rib protruding radially inward from an end portion of the second cylindrical portion on the other side in the axial direction. The rotor component includes: a seat portion that protrudes radially outward from the first cylindrical portion and supports the end portion of the second cylindrical portion on one side in the axial direction; and a rivet portion that extends radially outward from the end portion of the first cylindrical portion on the other side in the axial direction and overlaps with the annular rib from the other side in the axial direction.

[0069] (2) In the pump device of (1) above, A radial gap is provided between the first cylindrical portion and the second cylindrical portion, and the gap functions as a flow path groove for the flow of fluid in the pump chamber. The other side of the flow path groove in the axial direction is blocked by the annular rib.

[0070] (3) In the pump device of (2) above, On the inner circumferential surface of the second cylindrical portion, a plurality of magnet side ribs are arranged along the circumferential direction, protruding radially inward and extending along the axial direction. The gaps between the magnet side ribs adjacent to each other in the circumferential direction function as the flow path grooves.

[0071] (4) In the pump device of (3) above, An end portion of the magnet-side rib on the other side in the axial direction is connected to the annular rib.

[0072] (5) In the pump device of (3) or (4) above, A plurality of rotor member side ribs are arranged on the outer peripheral surface of the first cylindrical portion in the circumferential direction, protruding radially outward and extending in the axial direction. The front end surface of the magnet-side rib abuts against the front end surface of the rotor member-side rib, thereby dividing the flow path groove in the circumferential direction.

[0073] (6) In the pump device of any one of (2) to (5) above, An inlet port communicating with the flow path groove is provided between the seat portion and the second cylindrical portion.

[0074] (7) In the pump device of (6) above, The flow path groove comprises: a first groove portion extending in the axial direction; a second groove portion extending in the axial direction at a rear side of the first groove portion in the rotation direction of the rotor; and a third groove portion extending in the circumferential direction and connecting the ends of the first groove portion and the second groove portion on the other side of the axial direction. The inlet is communicated with the first groove portion.

[0075] (8) In the pump device of (6) or (7) above, The seat portion is provided with a recessed portion recessed toward one side in the axial direction, The inlet port is a gap between a bottom surface of the recessed portion and an end surface of the second cylindrical portion on one side in the axial direction.

[0076] (9) In the pump device of (8) above, A first protrusion protruding from the bottom surface of the recessed portion engages with a first recessed portion provided on an end surface of the driving magnet to form a rotation-stopping portion for preventing the driving magnet from rotating relative to the rotor member. Parts of the recessed portion on both sides of the first recessed portion in the circumferential direction form the inflow ports at two locations adjacent to the rotation stopper in the circumferential direction.

[0077] (10) In the pump device described in any one of (1) to (9) above, The impeller portion includes: a flange portion provided at an end portion of the rotor member on one side in the axial direction; and an impeller fixed to the flange portion from one side in the axial direction. The first cylindrical portion includes: a connecting portion extending in the axial direction between the flange portion and the seat portion; and a magnet holding portion embedded inside the driving magnet, the radial bearing being held inside the magnet holding portion. The inner side of the connecting portion becomes a first space through which the fluid in the pump chamber flows via the through hole that penetrates the connecting portion in the radial direction. The first space communicates with a bearing cooling flow path that penetrates the magnet holding portion in the axial direction. Explanation of symbols

[0078] 1. Pump device, 2. Housing, 3. Stator, 4. Rotor, 5. Support shaft, 6. Housing, 8. Driving magnet, 10. Motor, 11. Radial bearing, 12. Thrust bearing, 18. Cover, 19. Base plate, 20. Pump chamber, 21. Suction pipe, 22. Discharge pipe, 23. Upper wall, 24. Impeller, 25. Impeller part, 26. Disc part, 27. Support part, 28. Cylinder part, 29. Side wall, 31 . stator core, 32, 33. insulator, 35. coil, 40. rotor component, 41. first cylindrical portion, 42. seat portion, 43. rivet portion, 44. inlet, 45. flange portion, 46. through hole, 47. flow path groove, 48. bearing cooling flow path, 50. rotor component side rib, 51. first rib, 52. second rib, 60. resin sealing component, 61. first partition wall, 62. second partition wall Partition wall, 63. Bottom wall, 64. End, 65. Shaft hole, 66. Main body, 67. Columnar portion, 69. Connector housing, 71. Winding terminal, 81. Cylindrical portion, 82. Annular rib, 83. Magnet side rib, 84. First recess, 85. Gate mark, 110. Cylindrical portion, 111. Large diameter portion, 260. Central hole, 261. Blade portion, 410. Magnet holding portion, 411. Front end portion, 412. Connecting portion, 420. Notch portion, 421. Recess, 422. First convex portion, E. Stop portion, F. Flow path groove, F1. First groove portion, F2. Second groove portion, F3. Third groove portion, G1, G2. Gaps, H. First space, L. Rotation axis, L1. One side of the axis direction, L2. The other side of the axis direction, R1. The front side of the rotation direction, R2. The rear side of the rotation direction.

Claims

1. A pump device, characterized in that: have: a motor including a rotor and a stator surrounding an outer circumference of the rotor; and an impeller portion, which is arranged in a pump chamber provided on one side of the axial direction relative to the stator when the direction along the rotation axis of the rotor is defined as an axial direction, and rotates integrally with the rotor, The rotor includes: a rotor component including a first cylindrical portion extending in the axial direction; and a driving magnet surrounding an outer circumference of the first cylindrical portion, wherein a radial bearing is held inside the first cylindrical portion. The driving magnet includes: a second cylindrical portion that surrounds the outer periphery of the first cylindrical portion and extends in the axial direction; and an annular rib that protrudes radially inward from an end portion of the second cylindrical portion on the other side in the axial direction. The rotor component comprises: a seat portion, which protrudes radially outward from the first cylindrical portion and supports the end portion of the second cylindrical portion on one side of the axial direction; and a rivet portion, which extends radially outward from the end portion of the first cylindrical portion on the other side of the axial direction and overlaps with the annular rib from the other side of the axial direction.

2. The pump device according to claim 1, characterized in that A radial gap is provided between the first cylindrical portion and the second cylindrical portion, and the gap functions as a flow path groove through which the fluid in the pump chamber flows. The other side of the flow path groove in the axial direction is blocked by the annular rib and the caulking portion.

3. The pump device according to claim 2, characterized in that On the inner circumferential surface of the second cylindrical portion, a plurality of magnet side ribs are arranged along the circumferential direction, protruding radially inward and extending along the axial direction. The gaps between the magnet side ribs adjacent to each other in the circumferential direction function as the flow path grooves.

4. The pump device according to claim 3, characterized in that An end portion of the magnet-side rib on the other side in the axial direction is connected to the annular rib.

5. The pump device according to claim 3, characterized in that A plurality of rotor member side ribs are arranged on the outer peripheral surface of the first cylindrical portion in the circumferential direction, protruding radially outward and extending in the axial direction. The front end surface of the magnet-side rib abuts against the front end surface of the rotor member-side rib, thereby dividing the flow path groove in the circumferential direction.

6. The pump device according to claim 2, characterized in that An inlet port communicating with the flow path groove is provided between the seat portion and the second cylindrical portion.

7. The pump device according to claim 6, characterized in that The flow path groove comprises: a first groove portion extending along the axial direction; and a second groove portion extending along the axial direction at a rear side of the first groove portion in the rotation direction of the rotor; and a third groove portion extending in the circumferential direction and connecting the ends of the first groove portion and the second groove portion on the other side of the axial direction, The inlet is communicated with the first groove portion.

8. The pump device according to claim 6, characterized in that The seat portion is provided with a recessed portion recessed toward one side in the axial direction, The inlet port is a gap between a bottom surface of the recessed portion and an end surface of the second cylindrical portion on one side in the axial direction.

9. The pump device according to claim 8, characterized in that A first convex portion protruding from the bottom surface of the concave portion is fitted into a first concave portion provided on the end surface of the driving magnet. The inflow ports are formed at two locations in the recessed portion at both sides of the first convex portion in the circumferential direction.

10. The pump device according to claim 1, characterized in that The impeller portion includes: a flange portion provided at an end portion of the rotor member on one side in the axial direction; and an impeller fixed to the flange portion from one side in the axial direction. The first cylindrical portion includes: a connecting portion extending in the axial direction between the flange portion and the seat portion; and a magnet holding portion embedded in the inner side of the driving magnet, and the radial bearing is held in the inner side of the magnet holding portion. The inner side of the connecting portion becomes a first space through which the fluid in the pump chamber flows via the through hole that penetrates the connecting portion in the radial direction. The first space communicates with a bearing cooling flow path that penetrates the magnet holding portion in the axial direction.

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