Method for manufacturing stator for axial gap-type motor

Abstract

The present invention relates to a method for manufacturing a stator for an axial gap-type motor, which can minimize core loss due to eddy current by configuring split teeth using a multi-stage laminated core formed by stacking multiple sub-laminated cores having different shapes. According to the present invention, the method for manufacturing a stator comprises the steps of: preparing multiple sub-laminated cores having different shapes by primarily stacking multiple thin steel pieces for each type; preparing multiple divided teeth by secondarily stacking the multiple sub-laminated cores; forming a waterproof coating film on an exposed flat surface of a shoe of the multiple divided teeth, the waterproof coating film being made of a film thinner than a waterproof partition wall; and forming, when injection molding a body case, a front end of each of the multiple divided teeth by an insert molding method to be embedded in the waterproof partition wall.

Description

Manufacturing method of stator for axial gap type electric motor

[0001] The present invention relates to an axial gap type electric motor for a water pump, and more particularly, to a method for manufacturing a stator for an axial gap type electric motor, which can minimize core loss due to eddy current by forming a split tooth using a multi-stage laminated core formed by laminating a plurality of sub-laminated cores of different shapes in an axial gap type electric motor that separates a rotor and a stator using a waterproof partition, thereby increasing the efficiency of the motor and reducing the cost.

[0002] In general, a water pump applied to a vehicle is a device that functions to circulate coolant, and is configured to circulate coolant by rotating a pump impeller by being forcibly driven by a belt to suck in and discharge coolant, and an engine-driven water pump in which a seal unit is assembled inside to prevent coolant from leaking, and an electric water pump that drives an electric motor by electricity provided by a battery or the like, and circulates coolant by rotating an impeller by the electric motor to suck in and discharge coolant are representatively used.

[0003] Among these, the electric water pump has the advantage of increasing engine efficiency and thus improving fuel efficiency compared to the engine-driven water pump because it does not require engine driving power of the vehicle compared to the engine-driven water pump, and furthermore, it provides the advantage of being able to precisely control the temperature of the coolant, and thus has been widely applied to various vehicle models recently.

[0004] Among the above electric water pumps, the canned type electric water pump is a pump driven by an electric motor having a can-shaped sealed container inside a stator, and is structured such that a can structure is inserted between a rotor and a stator, and the hydraulic section is extended to the rotor section so that the rotor is immersed in cooling water, thereby allowing the injected water to appropriately cool the frictional heat generated in the rotor.

[0005] The above can type electric water pump is typically structured so that the magnets and stator core are positioned radially so that water flows into the magnets. However, the stator (core winding part) needs to be structured so that water cannot flow into it, so it has a waterproof structure using a waterproof can or injection molding. As a result, the air gap between the rotor and the stator core increases, resulting in a large magnetic flux loss. Therefore, it is difficult to achieve the desired pump (motor) capacity with a general magnet, so expensive rare earth magnets are generally used.

[0006] In general, water pumps (EWP), compressors, oil pumps, etc. use an internal rotor type motor, but in the case of an inner rotor type motor, the cross-sectional area of ​​the magnet (i.e., the effective area) is small, so rare earth elements are used to achieve performance, resulting in a high unit price.

[0007] In addition, water pump motors are inner rotor type motors, and the rare earth magnets (Nd-Fe-B) used in the rotor contain iron components, which can cause rust when in contact with water. Therefore, the rotor portion also adopts a waterproof structure. Therefore, the air gap between the rotor and the stator of water pump motors is large, which inevitably increases the amount of Nd used in the rotor magnet. However, if a rotor using rare earth magnets is adopted in this way, the manufacturing cost of water pump motors cannot be prevented from increasing.

[0008] The primary reason for using non-rare-earth magnets instead of rare-earth magnets in motors is their relative lower cost. Accordingly, the design goal of a motor is to achieve a motor with magnetic energy equivalent to that of a motor using rare-earth magnets, even when using less expensive, lower-magnetic non-rare-earth magnets.

[0009] Considering these points, the inventor of the present invention has proposed in Korean Patent Publication No. 10-2021-0108844 (Patent Document 1) a water pump having magnetic energy equivalent to that of an electric motor using a rare-earth magnet, even when using a low-cost ferrite magnet, which is a non-rare-earth magnet, by reducing the air gap by completely separating the rotor and the stator in an axial gap type electric motor using a waterproof thin-plate barrier.

[0010] The axial gap type electric motor for a water pump (EWP) of the above patent document 1 uses SMC (Soft Magnetic Composites) as a stator core, so it is not only about three times more expensive than a laminated core, but also has a problem of reduced motor efficiency due to core loss caused by eddy current.

[0011] The present invention has been conceived in consideration of such conventional problems, and its purpose is to provide a method for manufacturing a stator for an axial gap type electric motor, which forms a plurality of split teeth by first laminating a plurality of thin steel sheets to form a plurality of sub-laminated cores of different shapes, and secondarily laminating the obtained plurality of sub-laminated cores, and forms the shoes of the split teeth facing the rotor in a hexagonal shape, thereby maximizing the effective magnetic flux density and minimizing core loss due to eddy current, thereby improving the efficiency of the motor and reducing the cost.

[0012] According to one embodiment of the present invention, a method for manufacturing a stator for an axial gap type electric motor comprises the steps of: preparing a plurality of kinds of thin plate iron sheets by punching and forming them, each of which is formed in a "T" shape from a thin electrical steel sheet and has a pair of flanges extending left and right from a front end but having the same length but different widths; preparing a plurality of sub-laminated cores having different shapes by first laminating the plurality of thin plate iron sheets by type; preparing a plurality of split teeth by secondly laminating the plurality of sub-laminated cores, each of which includes a coil winding portion on which a coil is wound, an exposed plane disposed on an upper end of the coil winding portion, and a shoe having a pair of extended inclined surfaces, each of which has a flange extending to both sides from the exposed plane; It is characterized by including a step of forming a waterproof coating film made of a thinner film than the waterproof bulkhead on the exposed plane of the shoe of the plurality of split teeth; and a step of forming the body case by an insert molding method so that the tip portion of each of the plurality of split teeth is embedded in the waterproof bulkhead when injection molding the body case.

[0013] According to another embodiment of the present invention, a method for manufacturing a stator for an axial gap type electric motor comprises the steps of: preparing a plurality of kinds of thin sheet steel sheets by punching and forming, each of which is formed in a "T" shape from a thin sheet of electrical steel and has a pair of flanges extending from a front end to the left or right, the flanges having the same length but different widths or widths; preparing a plurality of sub-laminated cores having different shapes by first laminating the plurality of thin sheet steel sheets by type; preparing a plurality of split teeth by secondly laminating the plurality of sub-laminated cores, each of which includes a coil winding portion on which a coil is wound, an exposed plane disposed on an upper end of the coil winding portion, and a shoe having a pair of extended inclined surfaces, the shoes having flanges extending to both sides from the exposed plane; And, when injection molding a body case having the waterproof bulkhead, the step of forming a front end of each of the plurality of split teeth by an insert molding method so that it is embedded in the waterproof bulkhead, while simultaneously forming a waterproof coating film made of a thinner film than the waterproof bulkhead on the exposed plane of the shoe and extending from the waterproof bulkhead is characterized by including;

[0014] The upper surface of the above waterproof coating film can be set to form the same plane as the upper surface of the above waterproof bulkhead.

[0015] In addition, the plurality of split teeth may be supported by a pair of extended inclined surfaces of the shoe embedded in the waterproof bulkhead so as to prevent each of the plurality of split teeth from being separated by the magnetic force of the rotor.

[0016] Moreover, the plurality of sheet metal pieces may each include a rectangular body having a preset width and length, and a pair of flange portions extending perpendicularly from both upper sides of the body so that the width thereof gradually narrows, wherein the body is formed in a rectangular shape in which both sides in the longitudinal direction are parallel and the upper side and the lower side are also parallel, and the pair of flange portions may each have a shape in which the lower side extends perpendicularly from the body and the upper side is inclined from the upper side of the body so that the width thereof gradually narrows.

[0017] In this case, the number of layers of the plurality of sub-stacked cores can be set in the range of 2 to 5 layers.

[0018] The above plurality of sub-laminated cores include first and second sub-laminated cores having different shapes obtained by first laminating two types of a plurality of thin plate iron sheets having a "T" shape, each having the same length and width and a pair of flange portions extending left and right from a tip end portion with different lengths; and a third sub-laminated core formed by first laminating a plurality of thin plate iron sheets having a "T" shape, each having the same length but a narrow width and a pair of flange portions extending left and right from a tip end portion with a shorter length than the two types of thin plate iron sheets; wherein the plurality of split teeth can be formed by second laminating the first to third sub-laminated cores, respectively.

[0019] The above waterproof bulkhead has a support shaft receiving portion formed integrally in the center toward the lower space and having a groove formed in the center, and the plurality of split teeth are arranged in a ring shape centered on the support shaft receiving portion and can be arranged parallel to the support shaft.

[0020] A method for manufacturing a stator for an axial gap type electric motor according to the present invention may further include the steps of: winding a coil on a coil winding body of each of a plurality of bobbins, winding a start line and an end line of the coil around first and second alignment guide projections and fixing them; extending the leading ends of the start line and the end line downward; assembling the plurality of bobbins, each of which has a coil wound on the coil winding part of each of the plurality of split teeth; joining an assembly hole of a back yoke to a lower end of the coil winding part protruding from the lower end of the bobbin, and fixing the back yoke; and passing the leading ends of the start line and the end line of the coil through a coil assembly through-hole of a printed circuit board (PCB) and then connecting them to a motor drive circuit.

[0021] In addition, each of the plurality of bobbins includes a coil winding body having a through hole formed in the center into which a coil winding portion of the split teeth is inserted and a coil wound around the outer periphery thereof; and upper and lower flanges formed at both ends of the body to define an area in which the coil is wound, wherein the upper and lower flanges are formed in a hexagonal shape whose width narrows toward the center, and a shoe insertion portion formed around the entrance of the body into which a bottom surface of a shoe of the split teeth is inserted, wherein the shoe of the split teeth is formed in a hexagonal shape and may be formed smaller than the upper flange.

[0022] Moreover, each of the plurality of thin plate steel sheets may be made of electrical steel sheets of S18, and the back yoke may be made of electrical steel sheets of S60.

[0023] In general, it is difficult for SMC (Soft Magnetic Composites) type stator cores to avoid increased core loss due to eddy current.

[0024] As described above, in the present invention, a stator core is formed by combining a plurality of split teeth with an annular back yoke in an axial gap type motor that separates the rotor and the stator using a waterproof bulkhead, and the plurality of split teeth are formed by using a multi-layer laminated core formed by first laminating a plurality of thin steel sheets to form a plurality of sub-laminated cores of different shapes, and secondarily laminating the obtained plurality of sub-laminated cores, and by forming the shoe of the split teeth facing the rotor in a hexagonal shape, the effective magnetic flux density is maximized and the core loss due to eddy current is minimized, thereby promoting an increase in the efficiency of the motor and a reduction in the cost.

[0025] In this case, the unit price of the SMC (Soft Magnetic Composites) type core is 3,700 to 4,900 won / kg, while the silicon steel typically used in laminated cores costs 1,300 to 1,500 won / kg. Therefore, the SMC (Soft Magnetic Composites) type core has a cost burden more than three times higher than that of laminated cores.

[0026] However, in general, the core of the stator facing the rotor in an axial gap type motor can form a core with a high effective magnetic flux density by optimizing the shoe surface of the SMC type core, which is a laminated core obtained by stamping and forming thin silicon steel sheets and laminated with multiple thin iron sheets.

[0027] Accordingly, in the present invention, a plurality of sub-laminated cores of different shapes are formed by first laminating a plurality of thin steel sheets, and a multi-layer laminated core having a hexagonal shoe is formed by second laminating the obtained plurality of sub-laminated cores, thereby forming a plurality of split teeth. Thus, while using a low-cost laminated core, the effective magnetic flux density is maximized like an SMC type core, and core loss due to eddy current is minimized, thereby improving the efficiency of the motor.

[0028] Moreover, in the present invention, the air gap can be minimized by using a waterproof bulkhead between the rotor and the stator to separate them, and by waterproofing the surface of the stator core facing the rotor with an ultra-thin waterproof coating film, so that a ferrite magnet, which is a non-rare earth magnet, can be used.

[0029] The waterproof bulkhead, which is conventionally installed to separate the rotor and the stator, must also support the rotor's support shaft in the center. Therefore, for example, the waterproof bulkhead made of a resin such as PPS must be formed to a thickness of 0.9 mm, and there is a limit to reducing the thickness.

[0030] However, when the surface of the stator core (teeth) made of a laminated core is waterproofed with an ultra-thin waterproof coating film, the waterproof coating film can be formed to a thickness of 0.2 mm, and thus the air gap can be significantly reduced compared to a thick-film waterproof baffle structure, making it possible to use a ferrite magnet with a relatively low magnetic density compared to a rare earth magnet.

[0031] Moreover, the electric motor of the present invention is an axial gap type in which the rotor and stator are opposed to each other with a waterproof bulkhead interposed between them, using ferrite magnets, and can be used in an open structure without the need for a separate magnet waterproof structure, such as a rare earth magnet. That is, since the main component of a ferrite magnet is an oxide of iron (Fe), it does not rust easily, and therefore, unlike when a rare earth magnet (Nd magnet) is used, there is no need to consider a waterproof structure for the surface of the magnet exposed to water. Therefore, when a ferrite magnet is employed in the rotor, a waterproof structure is not required for the part in contact with water, so the air gap can be further reduced. This reduction in the air gap minimizes the leakage magnetic flux between the stator core and the magnets of the rotor, which can help increase the efficiency of the electric motor.

[0032] In this case, the axial gap type electric motor for the water pump (EWP) of the present invention is provided with a support shaft receiving portion in which a support shaft for rotatably supporting the rotor is integrally formed in the center of a waterproof bulkhead of a thick film for separating the rotor and the stator, which is disposed on the upper part of the body case, and the support shaft may be press-fitted and fixed to the support shaft receiving portion.

[0033] In the present invention, even if the support shaft receiving portion is formed in the waterproof bulkhead of the rear film, the air gap between the rotor and the stator core (teeth) is determined by an ultra-thin waterproof coating film formed on the surface of the stator core (teeth), so that the air gap can be determined regardless of the thickness of the waterproof bulkhead.

[0034] FIG. 1 is a perspective view of a water pump using an axial gap type electric motor according to one embodiment of the present invention.

[0035] Figure 2 is a front view of the water pump illustrated in Figure 1.

[0036] Figures 3a and 3b are axial cross-sectional views of a water pump according to the present invention, respectively.

[0037] Figure 4 is a cross-sectional view taken along line BB of Figure 2.

[0038] Figures 5 and 6 are an exploded perspective view and a completely exploded perspective view, respectively, of an assembly of a water pump according to one embodiment of the present invention.

[0039] Figures 7a and 7b are cross-sectional views taken along the CC line and the DD line, respectively, of the stator illustrated in Figure 6.

[0040] FIG. 8a and FIG. 8b are a perspective view and an exploded perspective view, respectively, of a stator according to one embodiment of the present invention.

[0041] FIGS. 9A to 9D are a perspective view, an exploded view, a cross-sectional view, and a perspective view of a split tooth, respectively, showing an assembly of a split tooth and a bobbin according to one embodiment of the present invention.

[0042] FIGS. 9E and 9F are exploded perspective views of the first to third sub-laminated cores used in manufacturing a split tooth according to one embodiment of the present invention, respectively, and plan views showing thin iron sheets used in the sub-laminated cores.

[0043] Fig. 10 is a manufacturing process diagram showing a method for manufacturing a stator according to one embodiment of the present invention.

[0044] Hereinafter, a preferred embodiment according to the present invention will be described with reference to the attached drawings.

[0045] In this process, the sizes and shapes of components depicted in the drawings may be exaggerated for clarity and convenience. Furthermore, terms specifically defined in consideration of the structure and operation of the present invention may vary depending on the intent or custom of the user or operator. Definitions of these terms should be based on the content throughout this specification.

[0046] When current flows through a wire wound around a coil, a magnetic field is generated through the coil's center according to Ampere's circuital law. Coils are widely used in electronic components such as electromagnets, inductors, transformers, electric motors, and generators.

[0047] Adding a ferromagnetic or ferrimagnetic material to the center of the coil can increase the magnetic field by hundreds or thousands of times. The coil's magnetic field penetrates the core material, magnetizing it, and the strong magnetic field of the core adds to the field generated by the wire.

[0048] The degree to which the magnetic field is enhanced by the core depends on the permeability of the core material. Because frequency-dependent energy losses can occur due to adverse effects such as eddy currents and hysteresis, it is desirable to use different core materials for coils used at different frequencies.

[0049] Because of the electrical conductivity of metals, when solid, one-piece metal cores are used in alternating current (AC) applications such as transformers and inductors, a changing magnetic field induces large eddy currents circulating within them, i.e., closed loops of current in a plane perpendicular to the magnetic field.

[0050] Current flowing through the resistance of a metal heats the metal through Joule heating, resulting in significant power loss. Therefore, solid iron cores are not used in transformers or inductors, replaced by non-conductive cores such as laminated or powdered iron cores or ferrite.

[0051] A laminated magnetic core consists of a stack of thin iron sheets coated with an insulating layer, arranged as parallel as possible to the magnetic flux lines. The insulating layer acts as a barrier to eddy currents, allowing them to flow only in narrow loops within the thickness of each single layer. Since the current in an eddy current loop is proportional to the loop area, this prevents most current from flowing, reducing eddy currents to a very small level. Since power dissipation is proportional to the square of the current, dividing a large core into narrower layers significantly reduces power losses. This suggests that thinner layers lead to lower eddy current losses.

[0052] In the present invention, a stator core is formed by combining a ring-shaped back yoke with a plurality of split teeth, and the plurality of split teeth use a multi-layer laminated core formed by laminating a plurality of sub-laminated cores of different shapes, thereby increasing the effective magnetic flux density and minimizing core loss due to eddy current, thereby improving the efficiency of the motor.

[0053] The axial gap type electric motor employing the non-rare earth magnet of the present invention is applied to a water pump (EWP), a compressor, an oil pump, etc., and in the following description, the axial gap type electric motor is applied to a water pump (EWP) as an example.

[0054] Referring to FIGS. 1 to 7b, a water pump (EWP) (200) using an axial gap type electric motor according to the present invention largely includes a pump housing (10), an axial gap type electric motor (100), an impeller (20), and a driver (50).

[0055] The above pump housing (10) has an inlet (11a) for introducing a fluid such as a coolant at the center of one end, an outlet (11b) for discharging the introduced fluid is formed extending at one end of the other end, a pump cover (11) having an open center at the other end, a body case (12) having an inverted cup shape that covers the open portion of the pump cover (11) to form a fluid flow passage (P) inside the pump cover (11), and has a lower space (15) at the lower side of the fluid flow passage (P), and an upper cover (13) that forms a sealed lower space (15) inside the body case (12) and houses a stator (40) of an electric motor (100) and a driver (50) for driving the stator (40), and is coupled to the lower end of the body case (12).

[0056] The above pump cover (11) and body case (12) are preferably formed in a cylindrical shape and have a mutually fixed joint structure.

[0057] For example, four fixing extensions (11c, 12a) are protruded between the pump cover (11) and the body case (12) for mutual fixing connection, and fixing screws or fixing bolts are fastened to the connecting holes formed in the center of the fixing extensions (11c, 12a).

[0058] Among the four fixing extensions (11c, 12a) above, one fixing extension (12a) of the body case (12) has an alignment groove formed to align the coupling position with the fixing extension (11c) of the pump cover (11), and the fixing extension (11c) of the pump cover (11) has a coupling protrusion formed to be coupled to the alignment groove.

[0059] In addition, a circular protrusion and a circular groove are formed on each flange between the pump cover (11) and the body case (12), and an O-ring (17a) for sealing is inserted into the groove.

[0060] Furthermore, a sealing O-ring (17b) can be inserted into the joint between the body case (12) and the upper cover (13) to maintain the sealing state of the lower space (15). In addition, it is also possible to realize a more perfect sealing state by joining the joint between the body case (12) and the upper cover (13) using a laser welding method.

[0061] A connector housing (13b) is extended from the lower surface of the upper cover (13) to which a terminal terminal (18) for applying a driving signal to the driver (50) from the outside is arranged.

[0062] The pump cover (11), body case (12) and upper cover (13) forming the above pump housing (10) can be formed using a resin such as, for example, PPS (Poly Phenylene Sulfide).

[0063] An impeller (20) having a rotor (30) of an electric motor (100) integrally formed on the lower side is disposed in a fluid flow passage (P) of a folded portion between the inlet (11a) and the outlet (11b) of the pump cover (11).

[0064] In addition, the open bottom of the pump cover (11) is extended to secure a wider space than the inlet (11a) so that the impeller (20) can be placed in the fluid flow passage (P), and a flange is extended to form a groove structure on the upper part of the body case (12) corresponding to the open bottom of the pump cover (11).

[0065] The impeller (20) has a plurality of blades (23) radially arranged between a circular upper plate (21) and a lower plate (22) so as to discharge a fluid such as cooling water flowing in from an inlet (11a) through an outlet (11b) arranged on the side. The upper plate (21) has a through hole formed in the center and has a shape with a diameter that increases from the top to the bottom, and the lower plate (22) is formed as a circular plate that surrounds the upper side and a part of the outer surface of the rotor (30). Accordingly, the lower plate (22) functions as a rotor support, and the lower plate (22) and the rotor (30) can be integrated by an insert molding method.

[0066] In addition, a bearing housing (24) is formed to protrude downward in the central portion of the lower plate (22), and a sleeve bearing (61) that rotatably supports the rotor (20) on a support shaft (60) is built into the bearing housing (24).

[0067] Considering that the above sleeve bearing (61) comes into contact with a fluid, it is preferable to use an oilless bearing such as a carbon bearing or a plastic bearing.

[0068] Meanwhile, the water pump (200) according to the present invention, as shown in FIGS. 3 to 9e, employs an axial gap type electric motor (100) including a core-type stator (40) arranged in a sealed lower space (15) inside the body case (12) as a driving means for rotating the impeller (20), and a rotor (30) arranged opposite the stator (40) in a fluid flow passage (P) outside the body case (12).

[0069] First, the rotor (30) is configured as a single body with the impeller (20) by sequentially installing a ring-shaped back yoke (31) and a magnet (32) on the lower surface of the lower plate (22). The magnet (32) of the rotor (30) may be formed of a plurality of N-pole and S-pole split magnet pieces, or a magnet in which the N-pole and S-pole are multi-polarly split and magnetized in a ring-shaped magnet may be used. The back yoke (31) may be formed by, for example, punching an electro-galvanized iron (EGI) plate into a ring shape and installing it on the back surface of the magnet (32) to form a magnetic circuit.

[0070] A thick waterproof partition (16) is installed on the upper part of the body case (12) to separate the stator (40) and the rotor (30), thereby implementing a completely waterproof structure for the stator (40). That is, the stator (40) placed in the sealed lower space (15) inside the body case (12) can be completely blocked from contact with water by the waterproof partition (16).

[0071] In the central portion of the above waterproof bulkhead (16), a support shaft receiving portion (12e) formed integrally with the lower portion of the support shaft (60) by an insert molding method is formed extending into the lower space (15), and a rotor (30) is rotatably supported on the support shaft (60) through a sleeve bearing (61).

[0072] The above-mentioned support shaft receiving portion (12e) has a three-step stepped groove (19) formed in the center, and a support shaft (60) is installed in the center of the groove (19), i.e., the third-step stepped portion, and a sleeve bearing (61) and the lower portion of the bearing housing (24) are supported in the first and second-step stepped portions of the groove (19), respectively. In this case, a support washer (62) is inserted in the second-step stepped portion of the groove (19) to minimize friction with the lower portion of the sleeve bearing (61).

[0073] A washer (63) is attached to the upper portion of the above support shaft (60), and a fixing bolt (64) is fastened to the support shaft (60) to prevent the rotor (30) and impeller (20) from being separated from the support shaft (60). The fixing bolt (64) prevents the washer (63), which minimizes friction when the rotor (30) and impeller (20) rotate, from being separated.

[0074] The waterproof bulkhead (16) for separating the stator (40) and the rotor (30) on the upper portion of the body case (12) may be formed to have a thickness equal to or thicker than the cylindrical portion (12c) of the body case (12) so that the support shaft (60) formed in the support shaft receiving portion (12e) can have sufficient support strength when the rotor (30) and the impeller (20) rotate.

[0075] In the present invention, as described later, the air gap between the magnet (32) of the rotor (30) and the shoes (412) of the plurality of split teeth (41) forming the stator core (45) of the stator (40) is designed to have a significantly reduced gap compared to a conventional structure. That is, an ultra-thin waterproof coating film (14) having a thickness of about 0.2 mm is formed on the exposed plane (414a) of the shoe (412) of the tooth (41) facing the magnet (32) of the rotor (30).

[0076] In this case, as described later, the plurality of split teeth (41) are formed integrally with their respective ends embedded in the waterproof bulkhead (16), as illustrated in Fig. 7b. In this case, a waterproof coating film (14) may be formed in advance on the rectangular exposed plane (414a) of the shoe (412) of the plurality of split teeth (41).

[0077] In addition, the waterproof coating film (14) can be formed together with the waterproof bulkhead (16) when forming the body case (12) by an insert molding method in which the tip portions of the plurality of split teeth (41) are embedded in the waterproof bulkhead (16) during injection molding. As a result, the upper surface of the waterproof coating film (14) is set to form the same plane as the upper surface of the waterproof bulkhead (16).

[0078] Accordingly, in the motor of the present invention, the overall air gap is determined to be 1.1 mm, which is the minimum distance of 0.9 mm between the magnet (32) and the waterproof bulkhead (16) plus 0.2 mm of thickness of the waterproof coating film (14), but the air gap of the conventional structure is determined to be 1.8 mm, which is the minimum distance of 0.9 mm between the magnet (32) and the waterproof bulkhead (16) plus 0.9 mm of thickness of the waterproof bulkhead (16).

[0079] In the electric motor of the present invention, the air gap is greatly shortened compared to the air gap of a conventional structure in which the stator core is placed in the internal space of a waterproof bulkhead, and thus the leakage magnetic flux is greatly reduced.

[0080] As a result, in the present invention, by forming a waterproof coating film (14) with a relatively thin thickness on the exposed plane (414a) of the shoe (412) of the tooth (41) facing the magnet (32) of the rotor (30), a ferrite magnet, which is a non-rare earth magnet that can be purchased at a low price, can be used as the magnet of the rotor (30), as described below.

[0081] As a result, the electric motor (100) of the present invention is an axial gap type in which the rotor (30) and the stator (40) face each other with an ultra-thin waterproof coating film (14) therebetween, and can be used in an open structure without the need for a separate waterproof magnet structure such as a rare earth magnet. That is, since the electric motor (100) according to the present invention uses a ferrite magnet as the magnet (32) of the rotor (30), even if it is operated for a long time in contact with the cooling water flowing in the fluid flow passage (P) inside the pump cover (11), the performance of the magnet does not deteriorate. Therefore, the electric motor (100) of the present invention can further reduce the air gap and increase efficiency compared to a conventional electric motor that employs a rare earth magnet having a waterproof magnet structure.

[0082] In addition, in the present invention, it is possible to reduce the air gap by separating the rotor (30) and the stator (40) using an ultra-thin waterproof coating film (14), so that even if a ferrite magnet, which is a non-rare earth magnet, is used, an axial gap type motor having the same magnetic energy as a motor using a rare earth magnet containing Nd can be implemented.

[0083] The above support shaft (60) may be formed integrally by insert molding in a manner in which a portion of the support shaft (60) is inserted into a support shaft receiving portion (12e) integrally formed in the central portion of the waterproof bulkhead (16) during injection molding of the body case (12), or may be fixed by being pressed into the support shaft receiving portion (12e) integrally formed in the central portion of the waterproof bulkhead (16). In this case, a portion of the support shaft receiving portion (12e) extends from the waterproof bulkhead (16) to the lower space (15) and has a sufficient contact area to firmly support the lower portion of the support shaft (60).

[0084] Below, a stator of an axial gap type motor according to one embodiment of the present invention is described.

[0085] As shown in FIGS. 3 to 9e, the stator (40) is placed in a lower space (15) that maintains a sealed state and is formed integrally with a waterproof bulkhead (16) and an ultra-thin waterproof coating film (14), and is placed axially opposite to the rotor (30) to form an axial gap type motor.

[0086] The above stator (40) includes a stator core (45) having a plurality of split teeth (41) and an annular back yoke (42) that interconnects the plurality of split teeth (41) to form a magnetic circuit, as shown in FIGS. 8a to 9e, a plurality of bobbins (43) made of an insulating material that are joined to the outer periphery of the coil winding portion (410) of each of the plurality of split teeth (41), and a coil (44) wound on the outer periphery of the bobbin (43).

[0087] The axial gap type electric motor (100) of the present invention includes a rotor (30) having an annular magnet (32) and a stator (40) having a plurality of split teeth (41) arranged in an annular shape facing the annular magnet (32).

[0088] In this case, when the plurality of split teeth (41) and the plurality of bobbins (43) are configured as six, for example, as shown in FIG. 8a and FIG. 8b, it is preferable that each of the split teeth (41) and the bobbin (43) be formed evenly within a circumferential angle of 60 degrees.

[0089] In addition, since the plurality of split teeth (41) and the plurality of bobbins (43) are arranged with their leading ends toward the center as shown in FIG. 4, as described later, the upper and lower flanges (431a, 431b) of the plurality of bobbins (43) have a leading end in a trapezoidal shape and a rear end in a rectangular shape combined to form an overall hexagonal shape while minimizing the distance between adjacent flanges to secure the maximum coil winding area inside.

[0090] The above plurality of bobbins (43) each have a through hole (432) formed inside into which a coil winding part (410) of a split tooth (41) is inserted, a coil winding body (430) on the outer periphery of which a coil (44) is wound, and upper and lower flanges (431a, 431b) are formed at both ends of the body (430) to define an area in which the coil (44) is wound.

[0091] Around the entrance of the above body (430), a shoe insertion part (433) into which the bottom surface of the shoe (412) of the tooth (41) is inserted is provided, and the shoe insertion part (433) is formed in a shape corresponding to the shape of the bottom surface of the shoe (412) of the split tooth (41).

[0092] In addition, the lower flange (431b) has first and second alignment guide protrusions (434, 435) protruding in a “U” shape to align the start line and end line of the coil (44) at regular intervals after winding them around one turn and fixing them.

[0093] The above coil winding body (430) is formed into a hexagonal shape overall by combining a square shape at the rear end and a trapezoidal shape at the front end, and the upper and lower flanges (431a, 431b) are formed to extend perpendicularly from both ends of the body (430), and the rectangular shape at the rear end and the trapezoidal shape at the front end are combined to form an overall hexagonal shape. The shape of the shoe insertion portion (433) also forms an approximately hexagonal shape overall.

[0094] The plurality of split teeth (41) according to the present invention include a plurality of laminated structures each having a “T” shape, as shown in FIGS. 9d and 9e, for example, at least three layers of first to third sub-laminated cores (Laminated cores) (41a-41c).

[0095] The number of layers of the sub-laminated cores (41a-41c) required to form the above-mentioned split teeth (41) can be varied in the range of 2 to 5 layers as needed, and have the same length (L).

[0096] The split tooth (41) in which the first to third sub-laminated cores (41a-41c) are laminated and combined is formed into an overall “T” shape, and includes a coil winding portion (410) in which a bobbin (43) made of an insulating material is coupled to the outer periphery to wind the coil (44); and a shoe (412) having an exposed plane (414a) arranged on the upper end of the coil winding portion (410) and a pair of extended inclined surfaces (414b, 414c) formed on the front surface by extending flanges on both sides from the exposed plane (414a).

[0097] The above split teeth (41) may be formed in a hexagonal shape so that the coil winding part (410) and the shoe (412) correspond to the body (430) or upper and lower flanges (431a, 431b) of the bobbin (43).

[0098] The first sub-laminated core (41a) includes a first coil winding portion (410a) having a rectangular cross-section and a first shoe (412a) formed to extend left and right on the upper portion of the first coil winding portion (410a), the second sub-laminated core (41b) includes a second coil winding portion (410b) having a rectangular cross-section and a second shoe (412b) formed to extend left and right on the upper portion of the second coil winding portion (410b), and the third sub-laminated core (41c) includes a third coil winding portion (410c) having a rectangular cross-section and a third shoe (412c) formed to extend left and right on the upper portion of the third coil winding portion (410c).

[0099] In this case, the first sub-laminated core (41a) and the second sub-laminated core (41b) have first and second coil winding parts (410a, 410b) of the same width (W1) and the same volume. However, the first shoe (412a) of the first coil winding part (410a) is formed to extend longer left and right than the second shoe (412b) of the second coil winding part (410b).

[0100] In addition, in the embodiment illustrated in FIG. 9e, the widths (W1) of the first sub-laminated core (41a) and the second sub-laminated core (41b) are exemplified as being the same, but it is also possible for the width (W1) of the first sub-laminated core (41a) to be formed wider than the width of the second sub-laminated core (41b).

[0101] Moreover, the width (W2) of the third sub-laminated core (41c) is formed to be narrower than the widths (W1) of the first sub-laminated core (41a) and the second sub-laminated core (41b), and the third shoe (412c) of the third sub-laminated core (41c) is formed to extend shorter to the left and right than the second shoe (412b) of the second coil winding portion (410b).

[0102] It is preferable that the first shoe (412a) of the first coil winding portion (410a), the second shoe (412b) of the second coil winding portion (410b), and the third shoe (412c) of the third sub-laminated core (41c) be set so that the left and right extension lengths gradually decrease to correspond to the hexagonal shape of the upper flange (431a) of the bobbin (43), as shown in FIG. 9d.

[0103] The reason for forming the split tooth (41) according to the present invention into a multi-layered structure is to maximize the area of ​​the shoe (412) facing the annular magnet (32) of the rotor (30) within a preset limited circumferential angle, and to increase the efficiency of the motor by increasing the effective magnetic flux density by reducing the leakage magnetic flux between the magnet (32) and the shoe (412) by maximizing the area of ​​the shoe (412).

[0104] The first to third sub-laminated cores (41a-41c) are prepared by forming a plurality of thin plate iron sheets (411) in a "T" shape by punching a thin electrical steel plate (silicon steel) as shown in FIG. 9f, and then, as shown in FIG. 9e, by laminating a plurality of thin plate iron sheets (411) in a "T" shape at a preset thickness.

[0105] In this case, the plurality of thin plate iron pieces (411) each include a rectangular body (411a) having a preset width and length, and a pair of flange portions (411c, 411d) extending perpendicularly from both sides of the upper end of the body (411a) so that the width thereof gradually narrows.

[0106] The above main body (411a) is formed into a rectangular shape with both sides in the longitudinal direction being parallel, and the upper side (411b) and the lower side also being parallel, and a pair of flange portions (411c, 411d) each have a lower side extending perpendicularly from the main body (411a) and an upper side having a shape inclined from the upper side (411b) of the main body (411a) so that the width of the flange portion gradually narrows.

[0107] The thin plate iron sheet (411) for the first and second sub-laminated cores (41a, 41b) is set to have the same width (W1) and length (L), and only the length of a pair of flange portions (411c, 411d) is manufactured to be different.

[0108] However, the sheet metal plate (411) for the third sub-laminated core (41c) has the same length (L) as the sheet metal plate (411) for the first and second sub-laminated cores (41a, 41b), but the width (W2) and the extension length of the pair of flange portions (411c, 411d) are formed shorter.

[0109] When a plurality of thin plate iron pieces (411) for the first to third sub-laminated cores (41a-41c) are prepared, the thin plate iron pieces (411) are laminated in a plurality of layers at a preset thickness to form the first to third sub-laminated cores (41a-41c), respectively.

[0110] After that, by stacking the first to third sub-stacked cores (41a-41c) again, one split tooth (41) as shown in Fig. 9d can be obtained, and a plurality of split teeth (41), for example, six split teeth (41) required to construct the stator (40) are prepared in the same manner as above.

[0111] As described above, the split teeth (41) formed by stacking the first to third sub-stacked cores (41a-41c) have an overall “T” shape as shown in FIG. 9d, and each includes a coil winding portion (410) on which a coil (44) is wound around the outer periphery, and a shoe (412) that extends perpendicularly to both sides from the tip of the coil winding portion (410) to expand to a larger area than the coil winding portion (410) and opposes the magnet (32) of the rotor (30).

[0112] In this case, the split tooth (41) has a shoe (412) arranged at the tip end with flanges extending to both sides, and is provided with an exposed plane (414a) located at the center of the tip end and parallel to the lower end of the coil winding portion (410), and a pair of extended inclined planes (414b, 414c) extending left and right to form inclined planes from the exposed plane (414a).

[0113] A waterproof coating film (14) made of a thinner film than the waterproof bulkhead (16) is formed on the exposed plane (414a) of the shoe (412), and the pair of extended inclined surfaces (414b, 414c) are embedded in and supported by the waterproof bulkhead (16).

[0114] That is, the plurality of split teeth (41) are supported by a pair of extended inclined surfaces (414b, 414c) of the shoe (412) being embedded in the waterproof bulkhead (16), so that the waterproof bulkhead (16) is formed to extend so as to prevent the split teeth (41) from being separated by the magnetic force of the magnet (32) of the rotor (30).

[0115] An ultra-thin waterproof coating film (14) having a thickness of, for example, about 0.2 mm is formed on the exposed plane (414a) of the shoe (412) of the split tooth (41) facing the magnet (32) of the rotor (30), and the upper surface of the waterproof coating film (14) can be set to form the same plane as the upper surface of the waterproof bulkhead (16).

[0116] The above back yoke (42) is connected at right angles to a plurality of split teeth (41) to form a magnetic circuit, and is formed by laminating thin electrical steel plates (silicon steel) with a predetermined thickness, similarly to the teeth. To this end, the back yoke (42) has a plurality of coupling holes (42c) in which a plurality of split teeth (41) are coupled to an annular body (42a) having a through hole (42b) formed in the center. In this case, the plurality of split teeth (41) must be arranged on the same circumference in the same direction as the axial direction at a predetermined distance from the support shaft (60), and therefore, the plurality of coupling holes (42c) of the back yoke (42) are arranged on the same circumference.

[0117] The outer circumference of the annular body (42a) has a plurality of, for example, three protrusions (42d), and a through hole formed in each of the three protrusions (42d) is used to fasten the back yoke (42) to the through hole of the fixing protrusion (12f) with a fixing screw or bolt. In addition, the outer circumference of the annular body (42a) has a plurality of, for example, three recesses (42e), and when assembling the back yoke (42) to the inner circumference of the cylindrical portion (12c) of the body case (12) in order to assemble the back yoke (42) with the rear end of the plurality of split teeth (41), the recesses (42e) serve to guide the assembly position of the back yoke (42) as three fixing protrusions (12d) for fixing a printed circuit board (PCB) (51) are inserted.

[0118] In addition, the stator core (45) of the present invention has a plurality of split teeth (41) arranged on the same circumference at a constant distance from the support shaft (60) in the same direction as the axial direction, and the rear ends of the plurality of split teeth (41) are each connected to a plurality of assembly holes (42c) of the back yoke (42).

[0119] A driver (50) is installed at the lower portion of the stator (40) to generate a rotating magnetic field by applying a driving signal to the U, V, and W three-phase coils (44) of the stator (40). The driver (50) includes a printed circuit board (PCB) (51) on which various electronic components forming a motor drive circuit are mounted.

[0120] Three fixing through holes (52) are formed on the outer periphery of the printed circuit board (PCB) (51) to fix the printed circuit board (PCB) (51) to the body case (12). In addition, the start line and end line of the coil (44) are assembled into the coil assembly through holes (53) of the printed circuit board (PCB) (51) and soldered.

[0121] As illustrated in FIGS. 3 and 4, six fixing projections (12d, 12f) for fastening fixing screws or fixing bolts are protruded from the inner periphery of the cylindrical portion (12c) of the body case (12). The number of the fixing projections (12d, 12f) may be formed corresponding to the number of the plurality of split teeth (41) of the stator (40). For example, when the split teeth (41) are composed of six as illustrated in FIG. 4, the number of the fixing projections (12d, 12f) may also be six, formed at the same circumferential angle on the inner periphery of the cylindrical portion (12c) of the body case (12) to partition and support the six split teeth (41).

[0122] A female thread for fastening a fastening screw or fastening bolt is formed in the center of the above-mentioned fixing protrusions (12d, 12f). The three fixing protrusions (12f) are used to fasten the back yoke (42), and the remaining three fixing protrusions (12d) are used to fasten the printed circuit board (PCB) (51).

[0123] Fig. 10 is a manufacturing process diagram showing a method for manufacturing a stator according to one embodiment of the present invention.

[0124] Below, a method for manufacturing a stator according to the present invention is described with reference to FIG. 10.

[0125] First, for example, using S18, which has a relatively higher silicon content than S60, as a non-oriented electrical steel (silicon steel) of 0.3 to 0.5T, as a thin plate, three types of thin plate iron sheets (411) for the first to third sub-laminated cores (41a to 41c) in a "T" shape as shown in Fig. 9f are prepared by punching and forming multiple pieces, and then each type is laminated at a preset thickness to manufacture the first to third sub-laminated cores (41a to 41c) as shown in Fig. 9e (S11).

[0126] Thereafter, the first to third sub-laminated cores (41a-41c) obtained are laminated to manufacture a plurality of split teeth (41). In this case, the split teeth (41) include a coil winding portion (410) to which a bobbin (43) is coupled and a shoe (412) facing a magnet (32) of a rotor (30).

[0127] After that, an exposed plane (414a) of a shoe (412) facing the magnet (32) of the rotor (30) is coated with epoxy, for example, to a thickness of 0.2 mm, to form an ultra-thin waterproof coating film (14) (S12).

[0128] In addition, after winding the coil (44) on the body (430) of the bobbin (43), the start line and end line of the coil (44) are wound around the alignment guide protrusions (434, 435) for one turn and fixed, and then the ends of the start line and end line are aligned at a constant interval and extended to a predetermined length (S17).

[0129] Next, a plurality of split teeth (41) having an ultra-thin waterproof coating film (14) formed on an exposed plane (414a) of a shoe (412) are arranged in a ring shape with the support shaft receiving portion (12e) as the center, as shown in FIG. 7b, and the exposed surface of the waterproof bulkhead (16) arranged on the upper portion of the body case (12) and the waterproof coating film (14) of the teeth (41) form a plane of the same height, and injection molding is performed so that only a pair of extended inclined surfaces (414b, 414c) of the shoe (412) of the teeth (41) is insert-molded into the waterproof bulkhead (16), thereby forming the body case (12) (S13).

[0130] In the above embodiment description, it is exemplified that a plurality of split teeth (41) are used in which an ultra-thin waterproof coating film (14) is formed on the exposed plane (414a) of the shoe (412) so that the exposed surface of the waterproof bulkhead (16) arranged on the upper part of the body case (12) and the waterproof coating film (14) of the teeth (41) form a plane of the same height, but the present invention is not limited thereto.

[0131] In the present invention, it is also possible to use a plurality of split teeth (41) on which an ultra-thin waterproof coating film (14) is not formed on the exposed plane (414a) of the shoe (412) and then insert-molded into a waterproof bulkhead (16) positioned on the upper portion of the body case (12), and then form an ultra-thin waterproof coating film (14) on the exposed plane (414a) of the shoe (412).

[0132] When injection molding the above body case (12), it is preferable that one end of the support shaft (60) be insert-molded into the groove (19) of the support shaft receiving portion (12e) and become integrated.

[0133] In addition, when injection molding the above body case (12), a support washer (62) may be inserted into the groove (19) of the support shaft receiving portion (12e) to minimize friction with the lower portion of the sleeve bearing (61), so that insert molding can be performed.

[0134] Next, a bobbin (43) having a coil (44) wound on the coil winding portion (410) of the tooth (41) extending toward the lower portion of the body case (12) is assembled (S14). In this case, the extension portions of the start line and end line of the coil (44) are directed toward the lower portion of the body case (12).

[0135] After that, the lower part of the coil winding part (410) protruding from the lower part of the bobbin (43) is joined to the assembly hole (42c) of the back yoke (42), and a fixing screw or fixing bolt is fastened to the through hole of the projection (42d) to prevent the back yoke (42) from coming off (S15). In this case, when the lower part of the coil winding part (410) is joined to the assembly hole (42c) of the back yoke (42) formed by laminating non-oriented electrical steel (silicon steel) of S60 thin plate, the bobbin (43) acts as a stopper that determines the assembly depth.

[0136] Additionally, the diameter of the back yoke (42) is set smaller than the circumference formed by the start line and the tip of the end line of the coil (44).

[0137] After that, the start and end wire ends of the coil (44) facing the bottom of the body case (12) are exposed to the bottom of the printed circuit board (PCB) (51) by passing through 12 through holes formed with coil assembly through holes (53) of the printed circuit board (PCB) (51), and then fixing screws or bolts are first fastened to three PCB fixing through holes (52) to fix the printed circuit board (PCB) (51), and then the start and end wire ends of the coil (44) exposed to the bottom of the printed circuit board (PCB) (51) are soldered and connected to the motor drive circuit of the printed circuit board (PCB) (51) (S16).

[0138] The water pump (200) according to the present invention may be configured as a BLDC motor having, for example, a 12-pole-9-slot or 8-pole-6-slot structure, with an axial gap type electric motor (100). When the electric motor (100) has an 8-pole-6-slot structure, when the coil (44) of the stator (40) is wound around six teeth (41) in a U, V, and W three-phase structure to form a circuit, the coils (U1-U2, V1-V2, W1-W2) may be wound around two split teeth (41) for each of the U, V, and W phases.

[0139] As described above, the axial gap type electric motor (100) for a water pump according to the present invention has a stator (40) disposed in a lower space (15) inside a body case (12), which is a waterproof space completely separated from a fluid flow passage (P) inside a pump cover (11), a rotor (30) formed integrally with an impeller (20) and disposed in the fluid flow passage (P), and the stator (40) and the rotor (30) have a structure separated by a thick-film waterproof partition (16).

[0140] In addition, in the present invention, a plurality of split teeth (41) of a stator (40) facing a magnet (32) of a rotor (30) are formed by forming a plurality of thin electrical steel plates (silicon steel plates) in a "T" shape, each having the same length (L) but different widths (W1, W2), and a pair of flange portions (411c, 411d) extending left and right from a tip portion, by punching and laminating a plurality of each type of thin steel plates (411) to prepare first to third sub-laminated cores (41a-41c), and then laminating the obtained first to third sub-laminated cores (41a-41c).

[0141] Moreover, the above-described plurality of split teeth (41) are formed of a laminated core formed by laminating first to third sub-laminated cores (41a-41c) of different shapes, and an ultra-thin waterproof coating film (14) is formed on an exposed plane (414a) forming the leading edge of a shoe (412), and a pair of extended inclined surfaces (414b, 414c) are insert-molded between the waterproof bulkhead (16) of the thick film of the body case (12).

[0142] Accordingly, in the axial gap type electric motor (100) for a water pump according to the present invention, the air gap between the stator (40) and the rotor (30) is set by an ultra-thin waterproof coating film (14) formed on the tip exposed plane (414a) of the split tooth (41) and the magnet (32) having an open structure without requiring a magnetic waterproof structure.

[0143] As a result, the electric motor (100) of the present invention can minimize the air gap compared to a conventional electric motor in which the tip of the tooth is arranged inside the waterproof bulkhead (16) of the thick film, thereby minimizing the leakage magnetic flux, and thus can achieve the same efficiency and torque increase as an electric motor using a rare earth magnet even when a ferrite magnet, which is a non-rare earth magnet, is used.

[0144] In addition, the electric motor (100) of the present invention is an axial gap type electric motor that uses a waterproof partition (16) to separate the rotor (30) and the stator (40), and the plurality of split teeth (41) use a multi-layer laminated core formed by laminating a plurality of sub-laminated cores (41a-41c) of different shapes, thereby increasing the effective magnetic flux density and minimizing core loss due to eddy current, thereby promoting an increase in the efficiency of the motor.

[0145] When a water pump control signal is applied to the driver (50) from a water pump (200) control device inside a vehicle, the driver (50) applies a drive signal to the stator coil (44) of the axial gap type motor (100) from the driver (50) when receiving a rotor position signal from a hall sensor (not shown), and the stator (40) generates a rotating magnetic field from a plurality of split teeth (41).

[0146] When a rotating magnetic field is generated from the plurality of split teeth (41) of the above stator (40), the rotor (30) placed in the fluid flow passage (P) through the ultra-thin waterproof coating film (14) rotates around the support shaft (60) together with the impeller (20), and as a result, cooling water is introduced from the inlet (11a) of the pump cover (11) according to the rotation of the impeller (20), and the introduced cooling water is discharged to the outlet (11b) along the fluid flow passage (P).

[0147] In the present invention, the impeller (20) and the rotor (30) disposed inside the fluid flow passage (P) are driven by the stator (40) of the electric motor (100) disposed outside the fluid flow passage (P) in a magnetic coupling manner, thereby realizing complete waterproofing of the stator (40) of the axial gap type electric motor (100).

[0148] Moreover, in the present invention, since the stator (40) of the electric motor (100) is completely isolated from the fluid flow passage (P), a separate waterproofing treatment can be omitted, and thus the air gap between the rotor (30) and the stator (40) of the electric motor (100) can be set to an optimal state, thereby improving the efficiency of the electric motor (100).

[0149] Although the present invention has been described and illustrated with specific preferred embodiments as examples, the present invention is not limited to the above embodiments, and various changes and modifications may be made by a person having ordinary skill in the art to which the invention pertains within a scope that does not depart from the spirit of the present invention.

[0150] The present invention relates to an axial gap type electric motor employing a non-rare earth magnet, and can be particularly applied to a longitudinal permanent magnet synchronous motor. The electric motor can be applied to a water pump (EWP), compressor, oil pump, etc. for cooling devices that circulate coolant for electrical components, batteries, fuel cell stacks, etc., in hybrid, electric, and fuel cell vehicles.

Claims

1. A method for manufacturing a stator for an axial gap type electric motor, wherein a rotor rotatably supported in a fluid flow passage of a pump housing and a stator disposed in a lower space to rotate the rotor are separated by a waterproof bulkhead of a body case having an inverted cup shape. A step of preparing a plurality of types of thin sheet steel sheets by punching and forming them, each of which is formed in a "T" shape from a thin sheet of electrical steel sheet and has the same length but different widths and a pair of flange portions that differ only in length extending left and right from the tip; A step of first laminating the plurality of thin steel plates by type to prepare a plurality of sub-laminated cores of different shapes; A step of preparing a plurality of split teeth including a coil winding part in which a coil is wound by secondarily stacking the plurality of sub-stacked cores, an exposed plane disposed on the upper part of the coil winding part, and a shoe having a pair of extended inclined surfaces with flanges extending from the exposed plane on both sides; A step of forming a waterproof coating film made of a thinner film than the waterproof bulkhead on the exposed plane of the shoe of the plurality of split teeth; and A method for manufacturing a stator for an axial gap type electric motor, comprising: a step of forming, by an insert molding method, the tip end of each of the plurality of split teeth so that it is embedded in the waterproof bulkhead when injection molding the body case; 2. In paragraph 1, A method for manufacturing a stator for an axial gap type electric motor, wherein the upper surface of the waterproof coating film is set to form the same plane as the upper surface of the waterproof bulkhead.

3. In paragraph 1, A method for manufacturing a stator for an axial gap type electric motor, wherein a pair of extended inclined surfaces of the shoe are embedded in the waterproof bulkhead and supported so as to prevent the plurality of split teeth from being separated by the magnetic force of the rotor.

4. In paragraph 1, The above plurality of thin plate iron pieces each include a rectangular body having a preset width and length and a pair of flange portions extending perpendicularly from both sides of the upper end of the body so that the width thereof gradually narrows. The above body is formed into a rectangular shape with both sides in the longitudinal direction being parallel and the upper and lower sides being parallel. A method for manufacturing a stator for an axial gap type electric motor, wherein the pair of flange portions each have a lower side extending perpendicularly from the main body and an upper side having a shape inclined from the upper side of the main body so that the width gradually narrows.

5. In paragraph 1, A method for manufacturing a stator for an axial gap type electric motor, wherein the number of layers of the plurality of sub-laminated cores is set in the range of 2 to 5 layers.

6. In paragraph 5, The above multiple sub-stacked cores First and second sub-laminated cores having different shapes obtained by first laminating two types of multiple thin steel sheets having a "T" shape with the same length and width and a pair of flanges extending from the tip to the left and right with different lengths; and A third sub-laminated core is formed by first laminating a plurality of thin plate iron sheets having a "T" shape, which have the same length but a narrow width and a pair of flanges extending from the tip to the left and right shorter than the two types of thin plate iron sheets; A method for manufacturing a stator for an axial gap type electric motor, wherein the plurality of split teeth are each formed by second-layering the first to third sub-laminated cores.

7. In paragraph 1, The above waterproof bulkhead is formed integrally in the center in the direction of the lower space and has a support shaft receiving portion with a groove formed in the center. A method for manufacturing a stator for an axial gap type electric motor, wherein the above plurality of split teeth are arranged in a ring shape centered on the support shaft receiving portion and are arranged parallel to the support shaft.

8. In paragraph 1, A step of winding a coil on a body for coil winding of each of a plurality of bobbins, then winding and fixing the start and end wires of the coil on the first and second alignment guide projections, and then extending the ends of the start and end wires downwards; A step of assembling each of the plurality of bobbins, each of which has a coil wound on each of the plurality of split teeth; A step of fixing the back yoke after joining the assembly hole of the back yoke to the lower part of the coil winding part protruding from the lower part of the bobbin; and A method for manufacturing a stator for an axial gap type electric motor, further comprising: a step of passing the start wire and the end wire of the coil through a coil assembly through-hole of a printed circuit board (PCB) and then connecting the end wire to a motor drive circuit.

9. In paragraph 8, The above plurality of bobbins are each A coil winding body having a through hole formed in the center into which the coil winding part of the split tooth is inserted and a coil wound around the outer periphery; and The body includes upper and lower flanges to define the area where the coil is to be wound at both ends, The upper and lower flanges are formed in a hexagonal shape with the width narrowing toward the center, A shoe insertion portion is formed around the entrance of the above body into which the bottom of the shoe of the above split teeth is inserted, A method for manufacturing a stator for an axial gap type electric motor, wherein the shoe of the above split teeth is formed in a hexagonal shape and is formed smaller than the upper flange.

10. In paragraph 8, The above plurality of thin plate steel sheets are each made of S18 electrical steel plates, The above back yoke is a method for manufacturing a stator for an axial gap type electric motor made of S60 electrical steel plate.

11. A method for manufacturing a stator for an axial gap type electric motor, wherein a rotor rotatably supported in a fluid flow passage of a pump housing and a stator disposed in a lower space for rotating the rotor are separated by a waterproof bulkhead of a body case having an inverted cup shape. A step of preparing a plurality of types of thin sheet steel sheets by punching and forming them, each of which is formed in a "T" shape from a thin sheet of electrical steel sheet and has the same length but different widths and a pair of flange portions that differ only in length extending left and right from the tip; A step of first laminating the plurality of thin steel plates by type to prepare a plurality of sub-laminated cores of different shapes; A step of preparing a plurality of split teeth including a coil winding part in which a coil is wound by secondarily stacking the plurality of sub-stacked cores, an exposed plane disposed on the upper part of the coil winding part, and a shoe having a pair of extended inclined surfaces with flanges extending from the exposed plane on both sides; and A method for manufacturing a stator for an axial gap type electric motor, comprising: a step of forming a waterproof coating film made of a thinner film than the waterproof bulkhead on an exposed plane of the shoe while forming a body case having the waterproof bulkhead by an insert molding method so that the tip portion of each of the plurality of split teeth is embedded in the waterproof bulkhead when injection molding; 12. In paragraph 11, A method for manufacturing a stator for an axial gap type electric motor, wherein the upper surface of the waterproof coating film is set to form the same plane as the upper surface of the waterproof bulkhead.

13. In paragraph 11, A method for manufacturing a stator for an axial gap type electric motor, wherein a pair of extended inclined surfaces of the shoe are embedded in the waterproof bulkhead and supported so as to prevent the plurality of split teeth from being separated by the magnetic force of the rotor.

14. In paragraph 11, The above plurality of thin plate iron pieces each include a rectangular body having a preset width and length and a pair of flange portions extending perpendicularly from both sides of the upper end of the body so that the width thereof gradually narrows. The above body is formed into a rectangular shape with both sides in the longitudinal direction being parallel and the upper and lower sides being parallel. A method for manufacturing a stator for an axial gap type electric motor, wherein the pair of flange portions each have a lower side extending perpendicularly from the main body and an upper side having a shape inclined from the upper side of the main body so that the width gradually narrows.

15. In paragraph 11, The above multiple sub-stacked cores First and second sub-laminated cores having different shapes obtained by first laminating two types of multiple thin steel sheets having a "T" shape with the same length and width and a pair of flanges extending from the tip to the left and right with different lengths; and A third sub-laminated core is formed by first laminating a plurality of thin plate iron sheets having a "T" shape, which have the same length but a narrow width and a pair of flanges extending from the tip to the left and right shorter than the two types of thin plate iron sheets; A method for manufacturing a stator for an axial gap type electric motor, wherein the plurality of split teeth are each formed by second-layering the first to third sub-laminated cores.

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