Electric water pump

Abstract

Provided is an electric water pump in which the assembly process management and the working process of a stator with respect to a motor housing are simplified. An electric water pump is provided with: a motor case (6) comprising a bottomed cylindrical inner wall (14) having a housing section (14a) for housing a rotor (12) to which an impeller (8) is attached, a cylindrical outer wall (15) disposed so as to surround the outside in the radial direction of the inner wall, and a connecting wall (16) for radially connecting the impeller-side end of the inner wall in the axial direction and the end of the outer wall; a stator (11) housed in a cylindrical housing space (20) formed between the inner wall and the outer wall; and a stator frame (24) having an annular base portion (25) fixed to an axial outer end portion of the outer wall, and four leg portions (26) each having an axial fixed end portion (26a) fixed to the base portion and each tip portion (26b) elastically contacting and held by an axial upper end surface (21b) of the stator (21).

Description

Technical Field

[0001] The invention relates to an electric water pump. Background Art

[0002] In the prior art, in order to save energy and resources and improve the fuel efficiency of automobiles, auxiliary equipment using the engine as a power source also tends to be electrified. As one of them, there is an electric water pump for cooling an automobile described in the following patent document 1.

[0003] The electric water pump comprises: a disc-shaped supporting member formed of a non-magnetic synthetic resin material; a cup-shaped outer shell member arranged in a manner covering one axial end portion of the supporting member; a fixing member formed of a cylindrical metal material arranged at the upper end portion of the supporting member; a fixing shaft inserted through the inner side of a cylindrical extension portion of a resin portion arranged in the center of the supporting member; a rotor arranged on the outer periphery of one axial end side of the fixing shaft through the extension portion; a pump portion arranged on the other axial end side of the fixing shaft; and a cylindrical stator arranged on the outer periphery side of the rotor and arranged on the base of the supporting member through the fixing member.

[0004] Furthermore, the stator is fixed to the support member by bolts through a bracket portion provided at a lower end of the fixing member while being pressed into the inner circumferential surface of the fixing member. Therefore, the position of the stator relative to the support member in the thrust direction and the radial direction is restricted.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-165783 (reference Figure 1 )

[0006] When assembling the stator with respect to the support member of the conventional electric water pump, as described above, the stator is first pressed into and fixed to the inner side of the metal fixing member, and in this state, the bracket portion of the fixing member is fixed to the support member by a plurality of bolts, so that the stator is assembled to the support member. Therefore, complicated installation process management and a large number of work processes have to be performed, which may lead to a decrease in installation work efficiency and an increase in work costs. Summary of the invention

[0007] Problems that the invention will solve

[0008] The present invention has been made in view of the technical problems of the conventional electric water pump, and one of its objects is to provide an electric water pump capable of simplifying the mounting process management of the stator to the motor case and the working process.

[0009] Means for solving the problem As a preferred embodiment, there is provided a motor housing, comprising: a bottomed cylindrical inner wall having a housing portion for housing a rotor on which an impeller is mounted, a cylindrical outer wall arranged to surround the radially outer side of the inner wall, and a connecting wall connecting the end of the inner wall on the impeller side in the axial direction to the end of the outer wall in the radial direction;

[0010] A stator housed in a cylindrical housing space formed between the inner wall and the outer wall and arranged coaxially with the rotor;

[0011] The stator frame comprises: an annular base fixed to the axial outer end of the outer wall, and a plurality of retaining portions, each of which has one axial end fixed to the base and each of which has the other axial end elastically contacting and retained by the stator.

[0012] Effects of the Invention

[0013] According to a preferred embodiment of the present invention, it is possible to simplify the assembly process management and the work process of the stator to the case, and as a result, it is possible to improve the installation work efficiency and reduce the work cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a longitudinal sectional view of the electric water pump according to the embodiment of the present invention.

[0015] Figure 2 It is an exploded perspective view of the electric water pump according to the present embodiment.

[0016] Figure 3 It is a partial perspective view showing a recessed portion provided in the motor case and a convex portion provided in the stator core according to the present embodiment.

[0017] Figure 4 This is a bird's-eye view of the stator frame provided in this embodiment.

[0018] Figure 5 This is a perspective view of the stator frame as viewed from the opposite side.

[0019] Figure 6 The figures show the connection between the base and the leg of the stator frame. (a) is a perspective view from the inside, and (b) is a perspective view from the outside.

[0020] Figure 7 This is a cross-sectional view showing a state in which the front end portions of the legs of the stator frame are caused to collide with the upper end surface of the stator and a part of the base portion is elastically deformed upward.

[0021] Description of Reference Numerals

[0022] 1…Electric water pump, 2…Pump unit, 3…Electric motor unit, 4…Control unit, 5…Pump housing, 6…Motor housing, 7…Pump chamber, 8…Impeller, 9…Suction pipe, 10…Discharge pipe, 11…Stator, 11…Rotor, 14…Inner wall, 14a…Accommodation unit, 15…Outer wall, 15a…Base wall, 15b…Plate wall, 16…Connecting wall, 18…Concave portion, 19…Groove, 20…Accommodation space, 21…Stator core, 21… a…convex portion, 21b…upper end surface (one end surface), 24…stator frame, 25…base, 25a…protrusion, 26…foot, 26a…fixed end (one end), 26b…front end (the other end), 27…base portion, 28…engaging convex portion, 29…support portion, 29a…mushroom-shaped head (locking portion), 30…cylindrical wall portion, 31…slit, 35…support shaft, 36…control housing, 37…circuit board. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the electric water pump according to the present invention will be described in detail based on the drawings.

[0024] (First Embodiment)

[0025] Figure 1 is a longitudinal sectional view of an electric water pump according to an embodiment of the present invention, Figure 2 is an exploded perspective view of the electric water pump of this embodiment. Figure 3 It is a partial perspective view showing a recessed portion provided in the motor case and a convex portion provided in the stator core according to the present embodiment.

[0026] The electric water pump 1 is, for example, a device used in a cooling device of a vehicle, uses a cooling medium (cooling water) as a working fluid, is assembled in a circulation loop connected to a heat exchanger (radiator), and is, for example, a device that supplies cooling water to an internal combustion engine, a drive engine, an inverter, etc. of a hybrid vehicle.

[0027] like Figure 1 As shown in FIG. 1 , the electric water pump 1 includes a pump unit 2, an electric motor unit 3 as a driving unit for driving the pump unit 2, and a control unit 4 for controlling the operation of the electric motor unit 3. Figure 1 In the figure, although the pump unit 2 is arranged on the lower side, the electric motor unit 3 is arranged on the central side, and the control unit 4 is arranged on the upper side, it is not limited to this arrangement and can also be arranged horizontally or in reverse according to specifications or applicable positions.

[0028] like Figure 1As shown, the pump unit 2 includes a pump chamber 7 formed between a pump housing 5 and a motor housing 6 and an impeller 8 accommodated in the pump chamber 7. The pump housing 5 includes a suction pipe 9 formed of, for example, a metal material and provided on the rotation axis of the impeller 8 to form a suction passage 9a opening into the pump chamber 7. The pump unit 2 also includes a discharge pipe 10 provided on a side portion of the pump housing 5 to form a discharge passage 10a communicating with the pump chamber 7 in a radial direction.

[0029] like Figure 2 As shown, the pump housing 5 is integrally provided with a plurality of (three in this embodiment) plate-like bosses 5a in a U-shape at a 120° position on the outer periphery, and a bolt hole 5b is formed through the center of each boss 5a. It should be noted that the pump housing 5 and the motor housing 6 are sealed by a sealing ring 13 sandwiched between the two.

[0030] like Figure 1 As shown, the pump unit 2 rotates the impeller 8 by the electric motor unit 3 to discharge the cooling water sucked into the pump chamber 7 from the suction passage 9a of the suction pipe 9 in the radial direction and supplies it to the internal combustion engine or the like from the discharge passage 10a of the discharge pipe 10.

[0031] The electric motor unit 3 is an inner rotor type brushless motor such as Figure 1 as well as Figure 2 As shown, it has: a motor case 6, which is connected by a plurality of (three in this embodiment) bolts 17 inserted into the bolt holes 5b of the bosses 5a at the upper end of the pump case 5; a stator 11, which is a stator arranged inside the motor case 6; and a rotor 12, which is a rotor rotatably arranged on the inner circumference of the stator 11. The stator 11 and the rotor 12 are accommodated and arranged inside the motor case 6.

[0032] The motor housing 6 is formed as a whole using synthetic resin material into a substantially cylindrical shape, and comprises: an inner wall 14 having a housing portion 14a for housing the rotor 12 on the inner side, an outer wall 15 arranged in a radially outer manner surrounding the inner wall 14, and a thin-walled annular connecting wall 16 that radially connects the end of the inner wall 14 on the axial side of the impeller 8 and the end of the outer wall 15.

[0033] The inner wall 14 is formed into a thin-walled bottomed cylindrical shape. Figure 1 In the embodiment, the upper end wall portion 14b on the upper side is formed into a substantially disk shape, and a covered cylindrical fixing portion 14c is provided at the center of the upper end wall portion 14b, into which an upper end portion 35a, an axial end portion of a support shaft 35 described later, is inserted and fixed. In addition, the housing portion 14a of the inner wall 14 is formed into a relatively large diameter cylindrical shape capable of housing the rotor 12.

[0034] like Figure 1As shown, the outer wall 15 includes a base wall portion 15 a formed in a thick cylindrical shape and a substantially square plate wall portion 15 b integrally provided at an upper end portion of the base wall portion 15 a . Figure 1 In the embodiment, the base wall portion 15a integrally has an annular portion 15c on the outer periphery of the lower end edge, and three boss portions 15d are provided at 120° positions on the outer periphery of the annular portion 15c. Three bolts 17 penetrating through the bolt holes 5b of the three boss portions 5a of the pump housing 5 are screwed into the internal threaded hole 15e formed through the center, so that each boss portion 15d is connected to the pump housing 5.

[0035] In addition, if Figure 1 As shown, the base wall portion 15a is formed with a cylindrical step-shaped seating portion 15h protruding inwardly at a position close to the inner peripheral surface of the connecting wall 16, and the lower end surface of the outer peripheral portion of the stator core 21 of the stator 11 is seated. Figure 2 as well as Figure 3 As shown, a single elongated recess 18 is formed in the inner peripheral surface of the base wall 15a in the axial direction. The recess 18 engages with a protrusion 21a radially protruding from the outer periphery of a stator core 21 described later to restrict the free rotation of the stator 11 in the circumferential direction.

[0036] The plate wall portion 15b is Figure 2 The four cylindrical bosses 15f at the two ends of the upper and lower sides are provided with four internal thread holes 15g, and the control housing 36 described later is fixed by bolts 39 screwed into the internal thread holes 15g. Figure 2 The upper surfaces of the two side portions are provided with a pair of left and right grooves 19, 19. Each groove 19, 19 is formed in a substantially rectangular cross-section and is formed elongated along the longitudinal direction of the upper surfaces of the two side portions.

[0037] The connecting wall 16 is formed in an annular shape, and constitutes a bottom wall of a cylindrical housing space 20 formed between the inner wall 14 and the outer wall 15 .

[0038] The stator 11 is entirely housed inside the housing space 20 and is coaxially arranged with the rotor 12, and includes a ring-shaped stator core 21 of magnetic material, a plurality of winding tubes 22 of synthetic resin material provided on the stator core 21, and a coil 23 wound around the outer periphery of each winding tube 22. The stator core 21 has a plurality of tooth-like portions on the inner periphery side, protruding in a ring shape from the outer side of each winding tube 22 (each coil 23).

[0039] Figure 4 is a bird's-eye view of the stator frame provided in this embodiment, Figure 5 is a perspective view of the stator frame viewed from the opposite side. Figure 61 is a diagram showing the connection between the base and the leg of the stator frame. (a) is a perspective view from the inside, and (b) is a perspective view from the outside. Figure 7 This is a cross-sectional view of a state in which the front ends of the legs of the stator frame collide with the upper end surface of the stator and a part of the base is elastically deformed upward. Figure 1 As shown, the stator 11 is accommodated in the accommodation space 20 between the inner wall 14 and the outer wall 15 of the motor case 6 , and is positioned and fixed in the axial direction (thrust direction) by the stator frame 24 .

[0040] The stator frame 24 is integrally formed of a synthetic resin material. Figure 2 , Figure 4 as well as Figure 5 As shown, it has: a circular ring-shaped base 25; fixed end portions 26a arranged at a position approximately 90° in the circumferential direction of the base 25, each of which is fixed to a retaining portion of the base 25, namely four legs 26; two long plate-shaped pedestals 27, 27 arranged at a position 180° from the outer circumference of the base 25; two engaging protrusions 28, 28 arranged on one end surface of each leg 26 side of each pedestal 27, 27; and two supporting pillars 29, a total of four, arranged on the other end surface of each pedestal 27, 27 on the opposite side of the engaging protrusions 28, 28.

[0041] The base 25 is formed in a relatively thin-walled annular plate shape, and a protrusion 25a protruding radially outward in a substantially trapezoidal shape in a plan view is provided at the outer peripheral edge connected to each fixed end 26a of each leg 26. Figure 1 As shown, the base 25 is provided with a cylindrical wall 30 at the lower inner peripheral edge on the side of each foot 26, and the cylindrical wall 30 can be embedded with the inner peripheral surface of the axial outer end of the base wall portion 15a of the outer wall 15 of the motor housing 6, that is, it can be embedded with the inner peripheral surface of the upper end opening portion 20a of the storage space 20 on the side of the plate wall portion 15b.

[0042] like Figure 4 as well as Figure 5 As shown, each leg 26 is formed into a slender plate of the same width, and the length L from the fixed end 26a to the other end on the side of the stator core 21, that is, the front end 26b is set to be the length of the front end 26b elastically abutting against the axial upper end face 21b of the stator core 21 when the base 25 abuts against the axial end face of the storage space 20 of the plate wall portion 15b.

[0043] In addition, if Figure 4 as well as Figure 6As shown in (a) and (b), a pair of slits 31, 31 are provided on both sides of the fixed end 26a of each leg 26, extending from the base 25 to the vicinity of each protrusion 25a. After the stator 11 is accommodated in the accommodation space 20, when the front end edge of each front end 26b is pressed from the axial direction and abutted against the axial upper end surface 21b of the stator core 21, the vicinity of each protrusion 25a of the base 25 between the two slits 31, 31 is as shown in FIG. Figure 7 As shown by the single-dot chain line, the legs 26 are bent and deformed upward to impart elastic force to each leg portion 26.

[0044] The cross-section of the two engaging protrusions 28, 28 is formed into a substantially rectangular shape, and extends in the tangential direction of the base 25, that is, extends along the length direction of the pedestal 27, 27, and is axially engaged with the two grooves 19, 19 of the motor housing 6. In addition, when each engaging protrusion 28, 28 is engaged with each groove 19, 19, the two are vibration-welded. That is, when the base 25 abuts against the hole edge of the upper end opening 20a of the storage space 20, when each engaging protrusion 28, 28 is engaged with each groove 19, 19, and when each front end 26b of each leg 26 elastically contacts the upper end surface 21b of the stator core 21 from the axial direction, the two are welded and joined by the vibration welding method.

[0045] The two support columns 29, 29 are respectively arranged and fixed to both ends of the bases 27, 27 in the longitudinal direction, and are respectively formed into small-diameter cylindrical shapes, and mushroom-shaped heads 29a, 29a that can be elastically deformed inward are respectively provided at the front ends.

[0046] The mushroom-shaped heads 29 a and 29 a can be snap-fitted (mechanically connected) to four small fixing holes 37 a provided in a circuit board 37 to be described later.

[0047] like Figure 1 as well as Figure 2 As shown in the figure, the rotor 12 is formed into a cylindrical shape, a plurality of permanent magnets 32 are held on the outer periphery, and the entire inner periphery including the permanent magnets 32 is molded by a magnetic pole holding portion 33 of a synthetic resin material. The magnetic pole holding portion 33 is provided integrally with the impeller 8 at the front end of the cylindrical shaft portion provided on the inner periphery of the rotor 12. In addition, a cylindrical portion 34 into which a support shaft 35 is inserted is provided inside the magnetic pole holding portion 33.

[0048] One axial end portion of the support shaft 35, namely the upper end portion 35a, is inserted and fixed to the fixing portion 14c, while the other end portion, namely the lower end portion 35b, is integrally provided with the suction pipe 9 and is inserted and fixed to the cup-shaped holding portion 9b disposed in the suction passage 9a. The rotor 12 is arranged so that the outer peripheral surface thereof is radially opposed to the inner peripheral surface of the stator core 21 through the inner wall 14 and a cylindrical air gap.

[0049] like Figure 1 as well as Figure 2 As shown, the control unit 4 includes a control housing 36 fixed to the upper surface of the plate wall portion 15 b of the outer wall 15 by a plurality of (four in this embodiment) bolts 39 and a circuit board 37 fixed to each support portion 29 of the stator frame 24 .

[0050] The control housing 36 is formed into a rectangular box shape using a heat transfer material such as an aluminum alloy material, and has a function as a heat dissipation device. The annular outer peripheral wall 36a abuts against the end surface of the plate wall portion 15b of the motor housing 6 from the axial direction and is connected by four bolts 39. That is, the control housing 36 is integrally provided with a frame-shaped protrusion on the outer peripheral edge of the plate wall portion 15b side, and four boss portions 36b are provided at the four corners of the frame-shaped protrusion. Each bolt 39 inserted into a bolt insertion hole 36c formed in the center of each boss portion 36b is screwed into the internal thread hole 15g of each boss portion 15f of the plate wall portion 15b and is connected to the plate wall portion 15b.

[0051] The circuit board 37 is formed in an approximately rectangular shape, and a plurality of electronic components 38 as electronic elements are mounted at predetermined positions. In addition, the circuit board 37 is formed with four fixing holes 37a formed at both ends in the longitudinal direction, into which the mushroom-shaped heads 29a of the pillars 29 are elastically inserted. For example, a bus bar provided inside the circuit board 37 is connected to the lead wires 23a of the coils 23 of the stator 11 through terminals.

[0052] (Operation and Effect of the Electric Water Pump of the Present Embodiment)

[0053] Hereinafter, the effects of the electric water pump according to the present embodiment will be described.

[0054] The supporting shaft 35 , the rotor 12 , the impeller 8 and other components are assembled in advance inside the pump housing 5 and the motor housing 6 , and the lower end of the base wall portion 15 a of the outer wall 15 is connected to the pump housing 5 by bolts 17 .

[0055] Then, when the stator 11 is positioned and fixed by the stator frame 2 in the storage space 20 of the motor housing 6, the stator 11 is first moved from the position Figure 1 The upper opening 20a is inserted into and accommodated in the accommodation space 20. Thus, the lower end surface 21c of the outer peripheral portion of the stator core 21 is seated on the upper surface of the seat portion 15h provided on the inner peripheral surface of the base wall portion 15a, and the axial movement thereon is restricted.

[0056] In addition, when the stator 11 is inserted into the housing space 20, the convex portion 21a provided on the outer peripheral surface of the stator core 21 and the concave portion 18 provided on the inner peripheral surface of the base wall portion 15a of the outer wall 15 are aligned and fit together from the axial direction. Therefore, the stator 11 is restricted from free rotation in the circumferential direction and is held at a predetermined axial and rotational position.

[0057] Then, the stator frame 24 is held and each leg 26 side is inserted into the storage space 20 from the upper end opening 20a. At this time, the stator frame 24 is inserted while being positioned in the rotation position in such a way that each engaging protrusion 28, 28 is aligned with each groove 19, 19, so that each engaging protrusion 28, 28 is engaged with each groove 19, 19.

[0058] Then, the base 25 of the stator frame 24 is pushed in the direction of the stator 11, with the front end 26b of each leg 26 of the stator frame 24 abutting against the upper end surface 21b of the stator core 21. In that case, as described above, each leg 26 pushes the stator core 21 in the direction of the seat 15h by the elastic force generated at 6 through each slit 31. In addition, in this state, the engaging protrusions 28, 28 and the grooves 19, 19 are welded and fixed by the vibration welding method. Therefore, the stator 11 is elastically positioned and fixed in the axial direction (thrust direction).

[0059] Next, if Figure 1 As shown, when the fixing small holes 37a of the circuit substrate 37 on which the electronic components 38 are pre-installed are aligned with the mushroom-shaped heads 29a of the pillars 29 of the stator frame 24 and pushed in, the circuit substrate 37 is mechanically fixed to the pillars 29 by snap connection. It should be noted that the circuit substrate 37 can also be fixed to the pillars 29 in advance before the legs 26 of the stator frame 24 are inserted into the storage space 20.

[0060] Then, by fixing the control housing 36 to the plate wall portion 15 b of the outer wall 15 with four bolts 39 , the entire assembly of the electric water pump 1 is completed.

[0061] As described above, according to the present embodiment, when the stator 11 is assembled with respect to the motor case 6, the stator frame 24 can be used to position the stator 11 in the storage space 20 of the motor case 6 in the thrust direction and fix it at the same time. That is, the stator frame 24 makes each engaging protrusion 28, 28 engage with each groove 19, 19 with respect to the stator 11 accommodated in the storage space 20 of the motor case 6, and makes each leg 26 bend and deform, and elastically contacts the axial upper end surface 21b of the stator core 21, and pushes the stator toward the seat 15h in the storage space 20. In this state, the engaging protrusions 28, 28 and the grooves 19, 19 are welded and fixed by the vibration welding method. Therefore, the stator 11 is reliably fixed while being positionally restricted in the storage space 20 in the thrust direction by the stator frame 24.

[0062] Therefore, since the stator 11 can be fixed to the motor housing 6 using only the stator frame 24, complicated process management as in the prior art described in the above publication is not required, and the assembly process is reduced, making the overall assembly work easier. As a result, the assembly efficiency of the stator 11 is improved and the cost is reduced.

[0063] In the present embodiment, since the slits 31 that impart elastic force to the legs 26 of the stator frame 24 to enable flexural deformation are continuously formed on both sides from the fixed end portions 26a of the legs 26 to the vicinity of the protrusions 25a, each leg 26 has good flexural deformation properties. Therefore, sufficient elastic holding force can be imparted to the stator 11. Thus, since the stator 11 is supported by the elastic force of each leg 26 of the stator frame 24, the transmission of vibrations and the like is effectively suppressed by the legs 26.

[0064] In addition, as described above, when the stator frame 24 is inserted into the storage space 20 of the motor housing 6, the stator frame 24 is radially positioned relative to the motor housing 6 by engaging the respective engaging protrusions 28, 28 of the respective pedestals 27, 27 formed on the stator frame 24 in the respective grooves 19, 19 formed on the outer wall 15, and is further fixed by welding to obtain a strong combined state.

[0065] Furthermore, since the motor case 6 and the stator frame 24 are formed of the same synthetic resin material, the respective fitting protrusions 28 , 28 and the respective recesses 19 , 19 can be easily connected by vibration welding.

[0066] In particular, since the motor case 6 is formed of a synthetic resin material instead of a metal material, it is possible to sufficiently suppress iron loss caused by magnetic flux leaking from the stator 11. As a result, it is possible to suppress a decrease in the engine efficiency of the electric motor unit 3.

[0067] The motor case 6 and the stator frame 24 are formed of synthetic resin material. As described above, the two can be fixed by welding, so the fixing work is easy and the heat of the electric motor unit 3 and the heat of the cooling water can be suppressed from being transferred to the circuit board 37 .

[0068] In addition, when the stator frame 24 places the base 25 against the edge of the hole of the upper end opening 20a of the storage space 20 disposed on the outer wall 15, as shown in FIG. Figure 1 As shown, the cylindrical wall 30 is so-called inlaid with the inner circumference of the upper end opening 20a of the storage space 20 of the outer wall 15 to perform radial positioning. Therefore, the radial positioning work of the stator frame 24 relative to the outer wall 15 can be easily and reliably performed. In addition, the cylindrical wall 30 functions as a reinforcing rib of the base 25, so that the rigidity of the base 25 can be improved.

[0069] In addition, when the stator 11 is inserted into the storage space 20 from the axial direction, the convex portion 21a of the stator core 21 is aligned with the concave portion 18 of the outer wall 15 and axially engaged, so that the stator 11 is prevented from turning around and positioned in the circumferential direction in the storage space 20 by the engagement of the concave and convex. Therefore, the installation work of the stator 11 is easy, and the stator 11 can be reliably positioned in the storage space 20 while being supported in the axial direction by the stator frame 24.

[0070] The present invention is not limited to the structure of the embodiment. For example, the welding method between the grooves 19, 19 of the motor case 6 and the engaging protrusions 28, 28 of the stator frame 24 may be ultrasonic vibration welding, heat welding or other welding methods in addition to the vibration welding method.

[0071] In the above embodiment, the fitting protrusions 28 , 28 of the stator frame 24 are welded to the grooves 19 , 19 of the motor case 6 , but the lower surface of the base 25 and the edge of the hole of the upper end opening 20 a of the storage space 20 may also be welded to fix them.

[0072] In addition, the pump unit 2 is not limited to the structure of the above-described embodiment, and may have other structures.

Claims

1. An electric water pump, characterized in that: have: A rotor having an impeller mounted thereon; A motor housing, comprising: a bottomed cylindrical inner wall having a housing portion for housing the rotor inside, a cylindrical outer wall arranged to surround the radially outer side of the inner wall, and a connecting wall connecting the axial end of the inner wall on the impeller side to the end of the outer wall in a radial direction; A stator housed in a cylindrical housing space formed between the inner wall and the outer wall and arranged coaxially with the rotor; The stator frame comprises: an annular base fixed to the axial outer end of the outer wall, and a plurality of retaining portions, each of which has one axial end fixed to the base and each of which has the other axial end elastically contacting and retained by the stator.

2. The electric water pump according to claim 1, characterized in that: Each of the holding portions is composed of a plurality of leg portions extending in the direction of one end surface in the axial direction of the stator.

3. The electric water pump according to claim 1, characterized in that: Each of the holding portions has a pair of slits formed in the radial direction on both sides of one end portion connected to the base portion, and each one end portion of each of the holding portions is provided to be able to bend and deform in the axial direction through the two slits.

4. The electric water pump according to claim 3, characterized in that: The base has a protrusion protruding radially outward on an outer surface connected to each end of each holding portion, The slit is formed from both sides of one end portion of the holding portion to the vicinity of the protruding portion.

5. The electric water pump according to claim 1, characterized in that: The motor housing is integrally formed of a synthetic resin material. The stator frame is also integrally formed of a synthetic resin material, and a base portion of the stator frame is fixed to an axially outer end portion of the outer wall by welding.

6. The electric water pump according to claim 1, characterized in that: At least two grooves are formed on the outer surface of the axial outer end of the outer wall along the tangential direction. At least two pedestals are provided on the outer periphery of the base of the stator frame, and at least two engaging protrusions engaged with the grooves are provided on the end surfaces of the two pedestals on the stator side. In a state where each fitting protrusion is fitted into each groove in the axial direction, each groove and each fitting protrusion are fixed by welding.

7. The electric water pump according to claim 6, characterized in that: A plurality of support portions are protrudingly provided on the surface of each seat portion opposite to the formation position of each engaging protrusion, and a locking portion is provided at the front end portion of each support portion, and the locking portion is elastically inserted into and locked in a small fixing hole formed in the circuit board.

8. The electric water pump according to claim 1, characterized in that: The stator frame includes a cylindrical wall that protrudes from an inner peripheral edge of the base portion in the same direction as the respective holding portions and is axially engageable with an inner peripheral surface of an axially outer end portion of the outer wall.

9. The electric water pump according to claim 1, characterized in that: A recess is provided in the axial direction on the inner peripheral surface of the outer wall of the motor housing facing the inner peripheral surface of the storage space. The stator has an outer surface provided with a convex portion that is fitted into the concave portion in the axial direction.

10. The electric water pump according to claim 1, characterized in that: The electric motor including the motor case, the rotor, and the stator is a three-phase brushless motor.

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