Electric water pump

Abstract

To provide an electric water pump in which the simplification of assembly schedule control and / or work process of a stator can be performed to a motor housing.SOLUTION: An electric water pump comprises a motor housing 6 and a stator holder 24. The motor housing comprises: a bottomed cylinder inner wall 14 having a housing 14a for accommodating a rotor 12 on which an impeller 8 is mounted; a cylinder outer wall 15 arranged surrounding the inner wall radially outside; and a connecting wall 16 connecting the end part of the inner wall on the impeller side in the axial direction and the end part of the outer wall in the radial direction. The stator holder comprises: a stator 11 accommodated in a housing space 20 formed between the inner wall and the outer wall; a circular base 25 fixed on the outer end part of the outer wall in the axial direction; and four legs 26, each fixed-end part 26a of which is fixed on the base in the axial direction, and each tip part 26b of which holds and elastically contacts the upper end face 21b of a stator core 21 in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For the purpose of saving energy and resources, there has been a demand for improving the fuel efficiency of automobiles, and there is a trend for auxiliary devices that are powered by engines to be electrified. One such example is an electric water pump for cooling automobiles, as described in Patent Document 1 below.

[0003] This electric water pump has a disk-shaped support member made of a non-magnetic synthetic resin material, a cup-shaped cover member provided to cover one axial end of the support member, a cylindrical fixed member made of a metal material provided at the upper end of the support member, a fixed shaft inserted inside a cylindrical extension portion of a resin portion provided in the center of the support member, a rotor arranged on the outer periphery of one axial end side of the fixed shaft via the extension portion, a pump portion provided on the other axial end side of the fixed shaft, and a cylindrical stator arranged on the outer periphery of the rotor and attached to the base of the support member via the fixed member.

[0004] The stator is press-fitted into the inner circumferential surface of the fixing member and is fixed to the support member by bolts via a stay portion at the lower end of the fixing member, thereby restricting the position of the stator relative to the support member in the thrust and radial directions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-165783 A (see FIG. 1) Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional electric water pump, as described above, in order to assemble the stator to the support member, the stator is first press-fitted and fixed inside the metal fixing member, and in this state, the stay portion of the fixing member is fixed to the support member with a plurality of bolts, thereby assembling the stator to the support member. This requires complicated assembly process management and many work steps, which may lead to a decrease in the efficiency of the assembly work and an increase in the work cost.

[0007] The present invention has been devised in consideration of the technical problems associated with the conventional electric water pumps described above, and one of its objects is to provide an electric water pump that can simplify the assembly process management and work process of the stator to the motor housing. [Means for solving the problem]

[0008] In one preferred embodiment, the motor housing includes a cylindrical inner wall having a bottom and a housing portion for housing a rotor having an impeller attached thereto, a cylindrical outer wall arranged to surround the radial outside of the inner wall, and a connecting wall that connects an axial end of the inner wall on the impeller side to an end of the outer wall from a radial direction; a stator that is accommodated in a cylindrical accommodation space formed between the inner wall and the outer wall and that is arranged coaxially with the rotor; The stator holder is characterized by having a ring-shaped base portion fixed to the axial outer end portion of the outer wall, and a plurality of retaining portions, each having one axial end portion fixed to the base and each having the other axial end portion elastically contacting and retaining the stator. Effect of the Invention

[0009] According to one preferred embodiment of the present invention, the process management and the work process for assembling the stator to the housing can be simplified, resulting in improved efficiency in the assembling work and reduced work costs. [Brief description of the drawings]

[0010] [Figure 1]1 is a vertical sectional view of an electric water pump according to an embodiment of the present invention; [Diagram 2] 1 is an exploded perspective view of an electric water pump according to an embodiment of the present invention; [Diagram 3] 4 is a partial perspective view showing a recess provided in a motor housing and a protrusion provided in a stator core of the embodiment. FIG. [Figure 4] FIG. 2 is an overhead view of a stator holder used in the present embodiment. [Diagram 5] FIG. 4 is a perspective view of the stator holder as viewed from the opposite side. [Figure 6] 1A and 1B show a connection portion between the base and the legs of the stator holder, in which (a) is a perspective view seen from the inside, and (b) is a perspective view seen from the outside. [Figure 7] 10 is a cross-sectional view showing a state in which the tip ends of the legs of the stator holder are abutted against the upper end surface of the stator, causing a part of the base to elastically deform upward. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric water pump according to the present invention will be described below in detail with reference to the drawings. [First embodiment] FIG. 1 is a longitudinal sectional view of an electric water pump according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the electric water pump of the embodiment, and FIG. 3 is a partial perspective view showing a recess provided in a motor housing and a protrusion provided in a stator core of the embodiment.

[0012] The electric water pump 1 is used, for example, in a vehicle cooling system, uses a cooling medium (cooling water) as the working fluid, is incorporated in a circulation circuit connected to a heat exchanger (radiator), and supplies cooling water to, for example, the internal combustion engine, drive motor, inverter, etc. of a hybrid vehicle.

[0013] 1, the electric water pump 1 has a pump section 2, an electric motor section 3 as a drive section that drives the pump section 2, and a control section 4 that controls the operation of the electric motor section 3. In this embodiment, the electric water pump 1 has the pump section 2 disposed on the lower side in FIG. 1, the electric motor section 3 disposed on the central side, and the control section 4 disposed on the upper side, but the arrangement is not limited to this, and they may also be disposed horizontally or in the opposite direction depending on the specifications and the application position.

[0014] 1, the pump section 2 includes a pump chamber 7 formed between a pump housing 5 and a motor housing 6, and an impeller 8 housed in the pump chamber 7. The pump housing 5 is made of, for example, a metal material, and is provided on the rotation shaft of the impeller 8. The pump housing 5 includes a suction pipe 9 that defines a suction passage 9a that opens into the pump chamber 7. The pump housing 5 also includes a discharge pipe 10 that is provided on the side of the pump housing 5 and defines a discharge passage 10a that radially communicates with the pump chamber 7. 2, the pump housing 5 is integrally provided with a plurality of (three in this embodiment) substantially U-shaped plate-like bosses 5a at 120° positions on the outer periphery, and a bolt hole 5b is formed through the center of each of the bosses 5a. The pump housing 5 and the motor housing 6 are sealed by a seal ring 13 interposed between them.

[0015] As shown in FIG. 1, the pump section 2 is adapted to radially discharge cooling water drawn into the pump chamber 7 from the suction passage 9a of the suction pipe 9 by rotating the impeller 8 by the electric motor section 3, and to supply the cooling water to an internal combustion engine or the like from the discharge passage 10a of the discharge pipe 10.

[0016] The electric motor unit 3 is an inner rotor type brushless motor, and as shown in Figures 1 and 2, has a motor housing 6 connected to the upper end of the pump housing 5 by multiple bolts 17 (three in this embodiment) inserted into each bolt hole 5b of each boss portion 5a, a stator 11 which is a fixed part arranged inside the motor housing 6, and a rotor 12 which is a rotor rotatably arranged on the inner side of the stator 11, and the stator 11 and rotor 12 are housed and arranged inside the motor housing 6.

[0017] The motor housing 6 is formed entirely of a synthetic resin material in an approximately cylindrical shape, and has an inner wall 14 having an accommodating portion 14a that accommodates the rotor 12 inside, an outer wall 15 arranged to surround the radial outside of the inner wall 14, and a thin, annular connecting wall 16 that radially connects the axial end of the inner wall 14 facing the impeller 8 to the end of the outer wall 15.

[0018] 1, an upper end wall portion 14b is formed in a substantially disk shape, and a covered cylindrical fixing portion 14c is provided in the center of the upper end wall portion 14b, into which an upper end portion 35a, which is one axial end portion of a support shaft 35 described later, is inserted and fixed. The accommodation portion 14a of the inner wall 14 is formed in a cylindrical shape with a relatively large diameter capable of accommodating the rotor 12.

[0019] As shown in Fig. 1, the outer wall 15 has a base wall portion 15a formed in a thick cylindrical shape and a substantially square plate wall portion 15b integrally provided at the upper end of the base wall portion 15a. The base wall portion 15a has an annular portion 15c integrally formed on the outer periphery of the lower end edge in Fig. 1, and three boss portions 15d are provided at 120° positions on the outer periphery of the annular portion 15c. Each boss portion 15d has an internal threaded hole 15e formed through the center thereof, into which three bolts 17 passing through bolt holes 5b in the three boss portions 5a of the pump housing 5 are screwed to join the pump housing 5.

[0020] 1, the base wall portion 15a has a cylindrical stepped seating portion 15h formed integrally with the base wall portion 15a and protruding inward at a position close to the connecting wall 16 on the inner circumferential surface thereof, on which the lower end face of the outer circumferential portion of the stator core 21 of the stator 11 is seated. As shown in FIGS. 2 and 3, the inner circumferential surface of the base wall portion 15a has a single elongated recess 18 formed along the axial direction. A protrusion 21a protruding radially from the outer periphery of the stator core 21, which will be described later, is fitted into the recess 18 to restrict free rotation of the stator 11 in the circumferential direction.

[0021] The plate wall portion 15b has four cylindrical boss portions 15f at both ends of the upper and lower sides shown in Fig. 2, and four female screw holes 15g are provided in the boss portions 15f, and a control cover 36 (described later) is fixed by bolts 39 screwed into the female screw holes 15g. The plate wall portion 15b also has a pair of left and right recessed grooves 19, 19 on the upper surface of each of the two sides shown in Fig. 2. Each of the recessed grooves 19, 19 is formed to have a substantially rectangular cross section and is elongated along the longitudinal direction of the upper surface of each of the two sides.

[0022] The connecting wall 16 is formed in an annular shape and constitutes the bottom wall of a cylindrical accommodation space 20 formed between the inner wall 14 and the outer wall 15 .

[0023] The stator 11 is entirely housed within the housing space 20 and arranged coaxially with the rotor 12, and has an annular stator core 21 made of a magnetic material, a plurality of bobbins 22 made of a synthetic resin material provided on the stator core 21, and coils 23 wound around the outer periphery of each of the bobbins 22. The stator core 21 has a plurality of teeth on its inner periphery that protrude in an annular shape outside each of the bobbins 22 (each of the coils 23).

[0024] FIG. 4 is an overhead view of the stator holder used in this embodiment, FIG. 5 is an oblique view of the same stator holder from the opposite side, FIG. 6 shows the connection portion between the base and legs of the stator holder, where (a) is an oblique view from the inside and (b) is an oblique view from the outside, and FIG. 7 is a cross-sectional view showing the state in which each tip of each leg of the stator holder is abutted against the upper end surface of the stator, causing part of the base to elastically deform upward.

[0025] As shown in FIG. 1, the stator 11 is accommodated in an accommodation space 20 between an inner wall 14 and an outer wall 15 of the motor housing 6, and is fixed while being positioned in the axial direction (thrust direction) by a stator holder 24.

[0026] The stator holder 24 is formed as a single unit from a synthetic resin material, and as shown in Figures 2, 4 and 5, has a circular base 25, four legs 26 which are retaining parts arranged at approximately 90° positions in the circumferential direction of the base 25 and have fixed ends 26a at each end in the axial direction fixed to the base 25, two long plate-shaped pedestal portions 27, 27 arranged at 180° positions on the outer periphery of the base 25, two mating protrusions 28, 28 arranged on one end face of each of the pedestal portions 27, 27 on the leg 26 side, and two support portions 29 arranged on each of the other end faces opposite the mating protrusions 28, 28 of each of the pedestal portions 27, 27, for a total of four support portions 29.

[0027] The base 25 is formed in a relatively thin annular plate shape, and is provided with protrusions 25a that are approximately trapezoidal in plan view and protrude radially outward from the outer periphery to which the fixed ends 26a of the legs 26 are joined. As shown in Fig. 1, the base 25 is provided, on the inner periphery of the lower surface on the leg 26 side, with a cylindrical wall 30 that can fit into the inner periphery of the axial outer end of the base wall portion 15a of the outer wall 15 of the motor housing 6, i.e., the inner periphery of the upper end opening 20a of the accommodation space 20 on the plate wall portion 15b side.

[0028] As shown in Figures 4 and 5, each leg 26 is formed in a long, thin plate shape of uniform width, and the length L from the fixed end 26a to the tip 26b, which is the other end on the stator core 21 side, is set to a length such that the tip 26b elastically abuts against the axial upper end surface 21b of the stator core 21 when the base 25 abuts against the axial end surface of the accommodating space 20 of the plate wall portion 15b.

[0029] 4 and 6(a) and (b), a pair of slits 31, 31 is provided on both sides of the fixed end 26a of each leg 26 from the base 25 to the vicinity of each protruding portion 25a. Then, after the stator 11 is accommodated in the accommodation space 20, when the tip edge of each tip portion 26b is pressed axially against the axial upper end surface 21b of the stator core 21 to abut, the vicinity of each protruding portion 25a of the base 25 between both slits 31, 31 is flexed upward as shown by the dashed line in FIG. 7, thereby applying an elastic force to each leg 26.

[0030] The two fitting protrusions 28, 28 are formed in a substantially rectangular cross section, extend in the tangential direction of the base 25, i.e., extend along the longitudinal direction of the pedestal portions 27, 27, and are adapted to be fitted in the two recessed grooves 19, 19 of the motor housing 6 in the axial direction. The fitting protrusions 28, 28 are vibration welded together in a state where they are fitted into the respective recessed grooves 19, 19. That is, the base 25 is welded together by vibration welding in a state where the fitting protrusions 28, 28 are fitted into the respective recessed grooves 19, 19 while abutting against the hole edge of the upper end opening 20a of the accommodation space 20, and where the tip portions 26b of the legs 26 are in elastic contact with the upper end surface 21b of the stator core 21 in the axial direction.

[0031] Each of the two support pillars 29, 29 is fixed to both longitudinal ends of each base portion 27, 27, and is formed into a small-diameter cylindrical shape with a mushroom-shaped head 29a, 29a at each tip that can elastically deform inward. Each of the fungus-like heads 29a, 29a can be snap-fitted (mechanically coupled) into each of four small fixing holes 37a provided in a circuit board 37, which will be described later.

[0032] 1 and 2, the rotor 12 is formed in a cylindrical shape, with multiple permanent magnets 32 held on its outer periphery, and the entire inner periphery including the permanent magnets 32 is molded with a magnetic pole holding portion 33 made of synthetic resin. The magnetic pole holding portion 33 has an impeller 8 integrally provided at the tip end of a cylindrical shaft portion on the inner periphery side of the rotor 12. Also, a cylindrical portion 34 into which a support shaft 35 is inserted is provided inside the magnetic pole holding portion 33.

[0033] The support shaft 35 has an upper end 35a, which is one end in the axial direction, inserted and fixed into the fixed portion 14c, while the other end, which is a lower end 35b, is inserted and fixed into a cup-shaped holding portion 9b that is integral with the suction pipe 9 and disposed in the suction passage 9a. The rotor 12 is disposed such that its outer circumferential surface faces the inner circumferential surface of the stator core 21 via the inner wall 14 in the radial direction, with a cylindrical air gap between them.

[0034] As shown in Figures 1 and 2, the control unit 4 has a control cover 36 fixed to the upper surface of the plate wall portion 15b of the outer wall 15 by multiple (four in this embodiment) bolts 39, and a circuit board 37 fixed to each support portion 29 of the stator holder 24.

[0035] The control cover 36 is formed in a rectangular box shape from a heat transfer material such as an aluminum alloy and functions as a heat sink, with an annular outer peripheral wall 36a abutting against an end face of the plate wall portion 15b of the motor housing 6 in the axial direction and connected to the plate wall portion 15b by four bolts 39. That is, the control cover 36 is integrally provided with a frame-shaped protrusion on the outer peripheral edge on 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 an internal threaded hole 15g of each boss portion 15f of the plate wall portion 15b to be connected to the plate wall portion 15b.

[0036] The circuit board 37 is formed in a substantially rectangular shape, and a plurality of electronic components 38, which are electronic elements, are attached at predetermined positions. The circuit board 37 has four fixing small holes 37a formed through both longitudinal ends thereof, into which the mushroom-shaped heads 29a of the support parts 29 are elastically inserted. The circuit board 37 has, for example, an internal bus bar connected to the lead wires 23a of the coils 23 of the stator 11 via terminals. [Functions and Effects of the Electric Water Pump of the Present Embodiment] The operation and effect of the electric water pump of this embodiment will be described below.

[0037] The various components, such as the support shaft 35, rotor 12, and impeller 8, are previously assembled inside the pump housing 5 and the motor housing 6, and the pump housing 5 is connected to the lower end of the base wall portion 15a of the outer wall 15 by bolts 17.

[0038] To position and fix the stator 11 in the accommodation space 20 of the motor housing 6 via the stator holder 24, first, the stator 11 is inserted into the accommodation space 20 from the upper end opening 20a located at the top in Fig. 1 and accommodated therein. Then, the lower end surface 21c of the outer periphery of the stator core 21 seats on the upper surface of the seating portion 15h on the inner periphery of the base wall portion 15a, and further axial movement is restricted.

[0039] Furthermore, when the stator 11 is inserted into the housing space 20 in this manner, the protrusions 21a on the outer peripheral surface of the stator core 21 are aligned with and fitted into the recesses 18 on the inner peripheral surface of the base wall portion 15a of the outer wall 15 in the axial direction. This allows the stator 11 to be held in a predetermined axial and rotational position while being restricted from free rotation in the circumferential direction.

[0040] Thereafter, the stator holder 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 rotational position of the stator holder 24 is positioned so that each of the mating protrusions 28, 28 matches each of the concave grooves 19, 19, and the mating protrusions 28, 28 are inserted while fitting into each of the concave grooves 19, 19.

[0041] Then, with the tip portions 26b of the legs 26 of the stator holder 24 in contact with the upper end surface 21b of the stator core 21, the base portion 25 of the stator holder 24 is pressed toward the stator 11. Then, as described above, the legs 26 press the stator core 21 toward the seating portion 15h by the elastic force generated at 6 through the slits 31. In this state, the fitting protrusions 28, 28 and the recessed grooves 19, 19 are welded and fixed by vibration welding. As a result, the stator 11 is elastically positioned and fixed in the axial direction (thrust direction).

[0042] 1, when the circuit board 37, on which electronic components 38 have already been attached, is pushed into the support columns 29 of the stator holder 24 while aligning the small fixing holes 37a with the mushroom-shaped heads 29a, the circuit board 37 is mechanically fixed to the support columns 29 by a snap fit. It is also possible to fix the circuit board 37 to the support columns 29 in advance before inserting the legs 26 of the stator holder 24 into the housing space 20.

[0043] Thereafter, the control cover 36 is fixed to the plate wall portion 15b of the outer wall 15 with four bolts 39, thereby completing the assembly work of the entire electric water pump 1.

[0044] As described above, according to this embodiment, in order to assemble the stator 11 to the motor housing 6, the stator 11 can be fixed in the accommodation space 20 of the motor housing 6 while being positioned in the thrust direction by using the stator holder 24. That is, the stator holder 24 fits the fitting protrusions 28, 28 into the recessed grooves 19, 19 of the stator 11 accommodated in the accommodation space 20 of the motor housing 6, and while the legs 26 are flexibly deformed, the stator holder 24 elastically contacts the axial upper end surface 21b of the stator core 21 and presses the stator in the direction of the seating portion 15h in the accommodation space 20. In this state, the fitting protrusions 28, 28 and the recessed grooves 19, 19 are welded and fixed by vibration welding. Therefore, the stator 11 is reliably fixed in the accommodation space 20 while being positionally regulated in the thrust direction by the stator holder 24.

[0045] Therefore, since the stator 11 can be fixed inside the motor housing 6 using only the stator holder 24, the complicated process management required in the prior art described in the above publication is no longer necessary, and the number of assembly steps is reduced, making the overall assembly work easier. As a result, the efficiency of the assembly work for the stator 11 can be improved and the cost can be reduced.

[0046] In this embodiment, the slits 31 that impart elastic force enabling bending deformation to the legs 26 of the stator holder 24 are continuously formed on both sides of each leg 26 from each fixed end 26a to the vicinity of each protrusion 25a, improving the bending deformation of each leg 26. This makes it possible to impart sufficient elastic holding force to the stator 11. In this way, the stator 11 is supported by the elastic force of each leg 26 of the stator holder 24, and the transmission of vibrations and the like is effectively suppressed by these legs 26.

[0047] As mentioned above, when inserting the stator holder 24 into the accommodating space 20 of the motor housing 6, the radial positioning of the stator holder 24 with respect to the motor housing 6 is achieved by fitting the respective mating protrusions 28, 28 formed on the respective base portions 27, 27 of the stator holder 24 into the respective concave grooves 19, 19 formed in the outer wall 15, and a strong connection is obtained by welding and fixing this position.

[0048] Furthermore, since the motor housing 6 and the stator holder 24 are formed from the same synthetic resin material, the fitting protrusions 28, 28 and the recessed grooves 19, 19 can be easily joined together by vibration welding.

[0049] In particular, since the motor housing 6 is made of a synthetic resin material rather than a metal material, it is possible to sufficiently suppress the occurrence of iron loss due to leakage magnetic flux from the stator 11. As a result, the decrease in motor efficiency of the electric motor unit 3 can be suppressed.

[0050] By forming the motor housing 6 and the stator holder 24 from synthetic resin material, as mentioned above, the two can be fixed together by welding, which makes the fixing work easier and prevents the heat of the electric motor section 3 and the coolant from being transmitted to the circuit board 37.

[0051] In addition, when the base 25 of the stator holder 24 is placed against the hole edge of the upper end opening 20a of the accommodation space 20 of the outer wall 15, the cylindrical wall 30 is fitted into the inner peripheral surface of the upper end opening 20a of the accommodation space 20 of the outer wall 15 in a so-called spigot-fit manner, as shown in Fig. 1, to thereby perform radial positioning of the stator holder 24 relative to the outer wall 15 easily and reliably. Moreover, the cylindrical wall 30 functions as a reinforcing rib for the base 25, thereby increasing the rigidity of the base 25.

[0052] Furthermore, when the stator 11 is inserted axially into the housing space 20, the protrusions 21a of the stator core 21 are aligned with the recesses 18 of the outer wall 15 and fitted into them axially, thereby preventing rotation in the circumferential direction and positioning the stator 11 within the housing space 20 through the fitting of the protrusions and recesses. This facilitates the assembly work of the stator 11 and, together with the axial support by the stator holder 24, enables reliable positioning within the housing space 20.

[0053] The present invention is not limited to the configuration of the above embodiment. For example, the welding method between each of the grooves 19, 19 of the motor housing 6 and each of the mating protrusions 28, 28 of the stator holder 24 can be ultrasonic vibration welding, heat welding, or other welding methods in addition to the vibration welding method.

[0054] In addition, in the above embodiment, the mating protrusions 28, 28 of the stator holder 24 and the recessed grooves 19, 19 of the motor housing 6 are welded and fixed, but it is also possible to weld the lower surface of the base 25 and the hole edge of the upper end opening 20a of the accommodating space 20.

[0055] Furthermore, the pump section 2 is not limited to the configuration of the above embodiment, and may have other configurations. [Explanation of symbols]

[0056] 1...electric water pump, 2...pump section, 3...electric motor section, 4...control section, 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 section, 15...outer wall, 15a...base wall section, 15b...plate wall section, 16...connecting wall, 18...recess, 19...recessed groove, 20...accommodation space, 2 1...stator core, 21a...convex portion, 21b...upper end surface (one end surface), 24...stator holder, 25...base, 25a...protruding portion, 26...leg portion, 26a...fixed end (one end) 26b...tip portion (other end), 27...pedestal 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 cover, 37...circuit board.

Claims

1. a rotor having an impeller attached thereto; a motor housing including a cylindrical inner wall having a bottom and a housing portion for housing the rotor therein, a cylindrical outer wall arranged to surround the radial outside of the inner wall, and a connecting wall connecting an axial end of the inner wall on the impeller side to an end of the outer wall from a radial direction; a stator that is accommodated in a cylindrical accommodation space formed between the inner wall and the outer wall and that is arranged coaxially with the rotor; a stator holder including a ring-shaped base portion fixed to an outer end portion of the outer wall in the axial direction, and a plurality of holding portions each having one end portion fixed to the base and each having the other end portion elastically contacting and holding the stator; An electric water pump comprising:

2. 2. The electric water pump according to claim 1, The electric water pump, wherein each of the holding portions is constituted by a plurality of legs extending toward one end face of the stator in the axial direction.

3. 2. The electric water pump according to claim 1, an end portion of the retaining portion that is connected to the base portion and has a pair of radially extending slits formed on both sides of the end portion, the end portion being configured to be flexibly deformed in the axial direction via the two slits;

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

5. 2. The electric water pump according to claim 1, The motor housing is integrally formed from a synthetic resin material, The electric water pump is characterized in that the stator holder is also integrally formed from a synthetic resin material, and a base portion of the stator holder is welded and fixed to an axial outer end portion of the outer wall.

6. 2. The electric water pump according to claim 1, At least two grooves are formed along a tangential direction on the outer surface of the outer end of the outer wall in the axial direction; At least two pedestal portions are provided on an outer periphery of a base portion of the stator holder, and at least two fitting protrusions that fit into the respective recessed grooves are provided on end faces of the stator side of each of the pedestal portions, The electric water pump according to claim 1, wherein the recessed grooves and the fitting protrusions are fixed to each other by welding in a state in which the fitting protrusions are fitted into the recessed grooves in the axial direction.

7. 7. The electric water pump according to claim 6, an electric water pump characterized in that a plurality of support pillars are protruding from the surface of each base portion opposite the position where each fitting protrusion is formed, and a locking portion is provided at the tip of each support pillar to be elastically inserted and locked into a small fixing hole formed in a circuit board.

8. 2. The electric water pump according to claim 1, The stator holder is characterized in that it has a cylindrical wall that protrudes from the inner peripheral edge of the base in the same direction as each of the retaining portions and is axially engageable with the inner peripheral surface of the axial outer end portion of the outer wall.

9. 2. The electric water pump according to claim 1, A recess is provided along the axial direction on an inner peripheral surface of an outer wall of the motor housing, the inner peripheral surface facing the accommodation space. an outer surface of the stator is provided with a protrusion that fits axially into the recess.

10. 2. The electric water pump according to claim 1, An electric water pump, wherein an electric motor having the motor housing, the rotor, and the stator is a three-phase brushless motor.

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