Slim axial-gap-type electric motor and electric water pump using same

Abstract

The present invention relates to a slim axial-gap-type electric motor using a multilayer printed circuit board, and an electric water pump using same. The electric motor of the present invention includes a rotor rotatably supported in a fluid flow path between a pump cover and a body case, and a stator which is integrated with the body case and generates a rotating magnetic field to rotationally drive the rotor, wherein the stator includes: a printed circuit board (PCB) which has a plurality of conductive coil patterns formed on each layer and has a plurality of through-holes formed in the center portions of respective coil patterns; a plurality of segmented cores which have teeth inserted into the plurality of through-holes and have head shoe portions exposed to the fluid flow path; and a back yoke which has through-holes that engage with the front end portions of the teeth protruding below the through-holes in the PCB, and the segmented cores core may be made of soft magnetic powder.

Description

Slim axial gap type electric motor and electric water pump using the same

[0001] The present invention relates to a slim axial gap type electric motor and an electric water pump using the same, and more particularly, to a slim axial gap type electric motor and an electric water pump using the same, which can significantly reduce the overall height of the pump while increasing the efficiency of the motor by using a slim stator in which teeth of a split core are joined to through holes of a laminated printed circuit board (PCB) in which a plurality of conductive coil patterns are formed for each layer, and a back yoke is joined to the rear end of the teeth protruding below the through holes.

[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] In addition, in the case of electric vehicles, hybrid vehicles, or fuel cell vehicles, the importance of electric water pumps is increasing compared to engine-driven water pumps because driving is performed with the engine stopped (in the case of hybrid vehicles) or even in situations where an engine to drive a water pump is not provided (in the case of electric vehicles or fuel cell vehicles).

[0005] Meanwhile, 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.

[0006] Korean Patent Publication No. 10-2021-0108844 (Patent Document 1) proposes an axial gap type electric motor for a water pump (EWP), including: a rotor rotatably supported in a fluid flow passage between a pump cover and a body case; a stator disposed in a lower space formed by the body case and an upper cover to generate a rotating magnetic field to rotate the rotor; and a partition disposed on an upper portion of the body case to separate the rotor and the stator; wherein the rotor includes a non-rare earth magnet.

[0007] The conventional electric motor structure of Patent Document 1 has a problem of low assembly productivity, as the stator core of the stator is formed in a "T" shape and is composed of a back yoke formed by laminating a plurality of teeth made of soft magnetic composites (SMC) and a plurality of electrical steel plates interconnecting the plurality of teeth.

[0008] In addition, conventional axial gap type motors for water pumps employ a stator in which coils are wound on a bobbin that forms a coil winding area on the outer periphery of the core while using a long stator core in a "T" shape, and since multiple stator cores are arranged parallel to the axial direction, it has been very difficult for the water pump to have a slim structure in the axial direction.

[0009] The present invention has been devised in consideration of such conventional problems, and its purpose is to provide a slim axial gap type electric motor and an electric water pump using the same, which comprises a plurality of split core heads formed of a soft magnetic powder (SMC) or a plurality of silicon steels laminated and formed by insert molding them into a body case, and then combines the teeth of the split cores protruding toward the rear with the through holes of a coil pattern provided on a laminated printed circuit board (PCB) and the through holes of a back yoke, thereby exposing the shoe portion of the split cores to a fluid flow passage, thereby minimizing the occurrence of air gaps and magnetic flux leakage, thereby increasing the efficiency of the motor, and which can significantly reduce the overall height of the pump while achieving complete waterproofing.

[0010] Another object of the present invention is to provide a slim axial gap type electric motor and an electric water pump using the same, which can increase the efficiency of the motor by minimizing the occurrence of air gaps and leakage flux by inserting teeth of a plurality of split cores made of soft magnetic powder (SMC) or formed by stacking a plurality of silicon steels into the central portion of each coil pattern of a laminated printed circuit board (PCB), assembling a power terminal pin to the laminated printed circuit board (PCB), and then integrating a stator assembly in which a back yoke is combined with the teeth of the split cores protruding from the rear of the laminated printed circuit board (PCB) by insert molding into a body case so that the shoe portion of the split cores is exposed to a fluid flow passage, thereby significantly reducing the overall height of the pump and making it possible to implement complete waterproofing.

[0011] Another object of the present invention is to provide a slim axial gap type electric motor and an electric water pump using the same, which can minimize air gaps and leakage flux generation by inserting teeth of a plurality of split cores into the central portion of each coil pattern of a laminated printed circuit board (PCB), assembling power terminal pins to the laminated printed circuit board (PCB), and integrating a stator assembly in which a back yoke is joined to the teeth of the split cores protruding from the rear of the laminated printed circuit board (PCB) by molding with an insulating heat-dissipating composite material, and then assembling the stator assembly to a body case so that a shoe portion of the split cores is exposed to a fluid flow passage.

[0012] Another object of the present invention is to provide a slim axial gap type electric motor and an electric water pump using the same, which can eliminate auxiliary PCBs for coil wiring and other additional bus bars by directly connecting U, V, W three-phase coils formed on a laminated printed circuit board (PCB) in which a plurality of coils are formed in a conductive coil pattern for each layer and a driving printed circuit board (PCB) in which a motor drive circuit is implemented using a power terminal pin or a lead wire.

[0013] Another object of the present invention is to provide a slim axial gap type electric motor having magnetic energy equivalent to that of an electric motor using a rare earth magnet even when a ferrite magnet, which is a non-rare earth magnet, is used, by reducing the air gap between the rotor and the stator, and an electric water pump using the same.

[0014] According to one embodiment of the present invention, an axial gap type electric motor for an electric water pump (EWP) includes: a rotor rotatably supported in a fluid flow passage between a pump cover and a body case; and a stator integrally formed with the body case to generate a rotating magnetic field to rotate the rotor, wherein the stator includes: a printed circuit board (PCB) having a plurality of conductive coil patterns formed in a spiral shape on each layer of a multilayer board and a plurality of through holes formed in the center of each coil pattern; a plurality of split cores having teeth inserted into the plurality of through holes and positioned so that a shoe portion of a head is exposed to the fluid flow passage; and a back yoke having a through hole engaged with a tip portion of the teeth protruding below the through holes of the printed circuit board (PCB), wherein the split core is characterized in that it is made of a soft magnetic powder (SMC).

[0015] The above-described laminated printed circuit board (PCB) is formed as a multilayer substrate having a plurality of coil patterns formed on each layer to form a U, V, W three-phase coil, and the plurality of coil patterns are connected in series for each of the U, V, and W phases, and the start line at the top of the plurality of coil patterns assigned to each of the U, V, and W phases connected in series is commonly connected to a common electrode terminal to form a neutral point (COM) for Y-connection, and the final end line at the top of the plurality of coil patterns assigned to each of the U, V, and W phases connected in series can be connected to the U, V, and W three-phase output terminals of the inverter circuit via the U, V, and W power terminal pins.

[0016] In addition, the laminated printed circuit board (PCB) may include a multilayer substrate having a plurality of coil patterns connected in series for each U, V, and W phase in each layer; and a lowermost substrate having a common electrode terminal to which the start lines of the uppermost phases of each U, V, and W among the plurality of coil patterns assigned to each U, V, and W phase connected in series to form a neutral point (COM) for Y-connection are commonly connected, and a U, V, and W output terminal to which a U, V, and W power terminal pin is connected to the final end line of each U, V, and W phase among the plurality of coil patterns assigned to each U, V, and W phase connected in series to connect to the U, V, and W three-phase output terminals of an inverter circuit.

[0017] The above multilayer substrate comprises: a first layer substrate in which, among two serially connected coil patterns for each of U, V, and W phases, a first coil pattern having a start line is formed as a spiral conductive pattern that rotates clockwise and is arranged on the left side, and a second coil pattern having an end line among the two coil patterns is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the right side; a second layer substrate in which, among two serially connected coil patterns for each of U, V, and W phases, a third coil pattern having a start line is formed as a spiral conductive pattern that rotates clockwise and is arranged on the right side, and a fourth coil pattern having an end line among the two coil patterns is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the left side; A third layer substrate, in which among the two coil patterns for each of U, V, and W, the fifth coil pattern having a start line is formed as a spiral conductive pattern that rotates clockwise and is arranged on the left side, and the sixth coil pattern having an end line is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the right side; and a fourth layer substrate, in which among the two coil patterns for each of U, V, and W, the seventh coil pattern having a start line is formed as a spiral conductive pattern that rotates clockwise and is arranged on the right side, and the eighth coil pattern having an end line is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the left side; wherein, in each layer, two coil patterns for each of U, V, and W phases can be alternately arranged for each of U, V, and W phases.

[0018] In this case, the split core may have a cross-section in the shape of a “T”.

[0019] In addition, the split core includes a head having a flat tip and a fan shape; and teeth extending from the head and having a triangular or rectangular shape corresponding to a through-hole of the laminated printed circuit board (PCB); wherein the head is arranged on the front surface of the laminated printed circuit board (PCB), and the teeth can have a tip end coupled to the through-hole of the back yoke after passing through the through-hole of the laminated printed circuit board (PCB).

[0020] According to another embodiment of the present invention, an axial gap type electric motor for an electric water pump (EWP) comprises: a rotor rotatably supported in a fluid flow passage between a pump cover and a body case; a stator disposed in a lower space formed by the body case and an upper cover to generate a rotating magnetic field to rotate the rotor; and a partition wall disposed on an upper portion of the body case to separate the rotor and the stator; wherein the stator comprises a plurality of split cores having a cross-section in a “T” shape and a head integrally formed with the partition wall such that a shoe portion is exposed to the fluid flow passage; a printed circuit board (PCB) having a plurality of conductive coil patterns formed in a spiral shape on each layer of a multilayer substrate, a plurality of through holes formed in the center of each coil pattern, and teeth of the split cores inserted into the through holes; and a back yoke having a through hole engaged with a tip end of the tooth protruding below the through hole of the printed circuit board (PCB).

[0021] The bulkhead of the above body case has a plurality of through holes at positions corresponding to the plurality of split cores, and the heads of the plurality of split cores coupled to the plurality of through holes are positioned so that the shoes are exposed to the fluid flow passage, and the split cores may be made of a soft magnetic powder (SMC).

[0022] The bulkhead of the above body case has a plurality of through holes at positions corresponding to the plurality of split cores, and the heads of the plurality of split cores coupled to the plurality of through holes are positioned so that the shoes are exposed to the fluid flow passage, and the split cores are formed by laminating silicon steel, and can be waterproof-sealed so that the exposed shoes and the bulkhead form the same plane.

[0023] According to one embodiment of the present invention, an electric water pump (EWP) includes a pump housing having a pump cover having an inlet for introducing fluid and an outlet for discharging the introduced fluid, and a body case coupled to a lower portion of the pump cover to form a fluid flow passage between the inlet and the outlet; a rotor rotatably supported in the fluid flow passage; an impeller integrally formed with the rotor on an upper side of the rotor; and a stator integrally formed with the body case to generate a rotating magnetic field to rotate the rotor; wherein the stator comprises a printed circuit board (PCB) having a plurality of conductive coil patterns formed in a spiral shape on each layer of a multilayer substrate and a plurality of through holes formed in the center of each coil pattern; a plurality of split cores having teeth inserted into the plurality of through holes and positioned such that a shoe portion of a head is exposed to the fluid flow passage; And a back yoke having a through hole that is coupled with the tip of the tooth protruding below the through hole of the printed circuit board (PCB); wherein the split core is characterized in that it is made of a soft magnetic powder (SMC).

[0024] The plurality of split cores are formed integrally with a partition wall for separating the rotor and the stator, each of which is positioned on the upper portion of the body case such that the shoe portion of the head is exposed to the fluid flow passage, and the printed circuit board (PCB) can be assembled such that the teeth are inserted into the plurality of through holes of each coil pattern.

[0025] As described above, in the present invention, the heads of a plurality of split cores made of a soft magnetic powder (SMC) or formed by laminating a plurality of silicon steels are integrated by insert molding them into a body case, and then the teeth of the split cores protruding toward the rear are joined to the through-holes of the conductive coil pattern provided on the laminated printed circuit board (PCB) and the through-holes of the back yoke, thereby exposing the shoe portion of the split core to the fluid flow passage, thereby minimizing the occurrence of air gaps and magnetic flux leakage, thereby promoting an increase in motor efficiency, and making it possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0026] The above laminated printed circuit board (PCB) has a plurality of coil patterns formed by patterning a spiral conductive pattern on each layer of the multilayer board.

[0027] In addition, in the present invention, a plurality of split cores made of soft magnetic powder (SMC) or formed by laminating a plurality of silicon steels are inserted into through holes provided in the center of each coil pattern of a laminated printed circuit board (PCB), a power terminal pin is assembled to the laminated printed circuit board (PCB), and a stator assembly having a back yoke joined to the teeth of the split cores protruding from the rear of the laminated printed circuit board (PCB) is integrally formed by insert molding the body case so that the shoe portion of the split core is exposed to the fluid flow passage, thereby minimizing the air gap and minimizing the generation of magnetic flux leakage, thereby promoting an increase in motor efficiency, and making it possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0028] In this case, it is preferable to insert insulating paper for insulation between the plurality of split cores and the laminated printed circuit board (PCB) and between the laminated printed circuit board (PCB) and the back yoke.

[0029] When the above stator assembly is integrated into the body case by insert molding, an insulating heat-dissipating composite material can be used.

[0030] Moreover, in the present invention, a plurality of coils are formed on a laminated printed circuit board (PCB) in which a conductive coil pattern is formed for each layer, and a motor drive circuit is directly connected to the outside using a power terminal pin or a lead wire, one end of which is located inside a connector housing, thereby eliminating auxiliary PCBs for coil wiring and other additional bus bars.

[0031] In addition, in the present invention, a plurality of split core teeth made of a soft magnetic powder (SMC) or formed by stacking a plurality of silicon steels are inserted into the central portion of each coil pattern of a laminated printed circuit board (PCB), a power terminal pin is assembled to the laminated printed circuit board (PCB), a stator assembly in which a back yoke is joined to the teeth of the split cores protruding from the rear of the laminated printed circuit board (PCB) is molded with an insulating heat-dissipating composite material to form an integral body, and then assembled to a body case, thereby minimizing the air gap and minimizing the generation of magnetic flux leakage by exposing the shoe portion of the split core to a fluid flow passage, thereby promoting an increase in motor efficiency, and making it possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0032] When integrating the above stator assembly by molding, the insulating heat-dissipating composite material may be a BMC (Bulk Molding Compound) material with a heat-dissipating effect among insert molding materials.

[0033] In this case, when the stator assembly is installed in an injection mold and molded with BMC (Bulk Molding Compound), the tip of the teeth or part of the back yoke of the split core may be exposed to serve as a position guide during insert molding.

[0034] In addition, in the present invention, when the thin plate partition formed integrally in the body case between the rotor and the stator is removed and the stator assembly is integrated by insert molding into the body case, the air gap is minimized by insert molding into the body case so that the shoe portion of the split core is exposed to the fluid flow passage, and at the same time, the leakage flux is minimized by combining the back yoke with the teeth of the split core, thereby promoting an increase in the efficiency of the motor, and complete waterproofing can be implemented while significantly reducing the overall height of the pump.

[0035] As a result, the present invention enables a reduction in the air gap, thereby providing a slim axial gap type motor having magnetic energy equivalent to that of a motor using a rare earth magnet containing Nd, even when using a non-rare earth magnet, such as a ferrite magnet. In addition, the use of a rare earth magnet containing bonded Nd can promote an increase in the performance of the motor.

[0036] Furthermore, the electric motor of the present invention is an axial gap type with a rotor and stator facing each other, and thus can be used in an open structure without the need for a separate magnetic waterproof structure such as a rare earth magnet. Therefore, compared to conventional electric motors employing rare earth magnets, the air gap can be further reduced, thereby increasing the efficiency of the electric motor.

[0037] In addition, in the present invention, a plurality of coil patterns patterned on a laminated printed circuit board (PCB) can be formed, and a Y-connection (neutral point) of a U, V, W three-phase coil can be easily implemented using a laminated printed circuit board (PCB).

[0038] In the present invention, a slim structure can be realized by having a slim stator and arranging the main printed circuit board (PCB) for the motor drive circuit outside the pump housing, and it is also possible to arrange the main printed circuit board (PCB) for the motor drive circuit inside the pump housing.

[0039] Fig. 1 is a perspective view of an electric water pump using an axial gap type electric motor according to the present invention.

[0040] FIG. 2 is an axial cross-sectional view of an electric water pump using an axial gap type electric motor according to a first embodiment of the present invention.

[0041] FIG. 3 is a front view of an electric water pump using an axial gap type electric motor according to a second embodiment of the present invention.

[0042] FIG. 4 is a plan view of an electric water pump using an axial gap type electric motor according to a second embodiment of the present invention.

[0043] Figures 5a and 5b are cross-sectional views taken along line AA and line BB of Figure 4, respectively.

[0044] Figure 6 is an exploded perspective view of each module of an electric water pump using an axial gap type electric motor according to a second embodiment of the present invention.

[0045] Figure 7 is a completely exploded perspective view of an electric water pump using an axial gap type electric motor according to a second embodiment of the present invention.

[0046] FIG. 8 and FIG. 9a are a cross-sectional view and an exploded perspective view, respectively, of a stator of an axial gap type motor according to the present invention.

[0047] Figure 9b is a cross-sectional view of a split core applied to a stator according to the present invention.

[0048] FIGS. 10A to 10E are plan views each showing the first to fifth layer PCB pattern diagrams of a laminated printed circuit board (PCB) according to the present invention.

[0049] Fig. 11 is an equivalent circuit of a coil wiring circuit formed by a plurality of coil patterns of a laminated printed circuit board (PCB) according to the present invention.

[0050] Figures 12 and 13 are manufacturing process diagrams showing a method for manufacturing a stator for an axial gap type electric motor according to the present invention.

[0051] Hereinafter, a preferred embodiment according to the present invention will be described with reference to the attached drawings.

[0052] 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.

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

[0054] Referring to FIG. 1, an electric water pump (EWP) (100) using an axial gap type motor according to a first embodiment of the present invention largely includes a pump housing (10), an axial gap type motor (200), and an impeller (20).

[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 (14) outside the fluid flow passage (P), and an upper cover (13) in which a stator (40) of an electric motor (200) built into the sealed lower space (14) inside the body case (12) is built and is coupled to the lower end of the body case (12).

[0056] The pump cover (11) above has an O-ring (17) attached to the outer circumference of the inlet (11a) to be used for sealing when combined with the fluid supply unit that supplies fluid.

[0057] In the present invention, the driver for driving the stator (40) may be placed outside the pump housing (10) to form a slim electric water pump (EWP) (100). However, it is also possible for the driver to be formed integrally on a laminated printed circuit board (PCB) placed inside the pump housing (10).

[0058] The above pump cover (11) and body case (12) are preferably formed in a cylindrical shape and have a mutually fixed connection structure. Between the pump cover (11) and the body case (12), a fixing screw or fixing bolt (11e) is fastened to a coupling hole (11d, 12b) provided in a plurality of protrusions (11c, 12a) protruding from the outer periphery of the pump cover (11) and the body case (12) for mutually fixed connection.

[0059] Additionally, an O-ring (19) for sealing can be inserted into the outer peripheral portion where the pump cover (11) and the body case (12) are mutually joined.

[0060] Moreover, an O-ring (18) is inserted into the joint between the body case (12) and the upper cover (13) to maintain the sealing state of the lower space (14).

[0061] In addition, it is possible to achieve a more perfect sealing state by joining the joint between the body case (12) and the upper cover (13) using a laser welding method.

[0062] A connector housing (13a) is integrally extended from the lower portion of one side of the upper cover (13) to apply a driving signal from a driver disposed externally to a laminated printed circuit board (PCB) (50) required to form a stator (40) disposed inside the housing (10). U, V, W power terminal pins (55c) connected to the laminated printed circuit board (PCB) (50) are built into the interior of the connector housing (13a).

[0063] 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).

[0064] An impeller (20) having a rotor (30) of an electric motor (200) integrally formed on the lower side is disposed in the fluid flow passage (P) of the folded portion between the inlet (11a) and the outlet (11b) of the pump cover (11).

[0065] 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 groove structure is formed in the upper part of the body case (12) corresponding to the open bottom of the pump cover (11) in which a rotor (30) formed integrally with the lower part of the impeller (20) is placed.

[0066] The above 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 (21a) formed in the center and has a shape of a narrow upper and lower plate with a diameter that increases from the upper side to the lower side, and the lower plate (22) is formed as a circular plate that surrounds the upper side and the outer periphery of the rotor (20).

[0067] The above pump cover (11) has a flange formed to extend from the lower portion of the body that accommodates the impeller (20) inside so as to have the same outer diameter as the outer diameter of the body case (12). A plurality of reinforcing ribs (11f) are formed radially on the outer circumference of the body to reinforce the strength of the body.

[0068] Accordingly, the lower plate (22) is formed with the same diameter as the upper plate (21) corresponding to the diameter of the flange. In this case, the lower plate (22) and the rotor support (33) of the rotor (30) can be integrated using an insert molding method.

[0069] In addition, a bearing housing (62) is formed to protrude downward in the center of the rotor support (33), and a sleeve bearing (61) that rotatably supports the rotor support (33) of the rotor (30) is installed in the bearing housing (62), and a thrust bearing (63) is inserted into the lower side of the sleeve bearing (61).

[0070] The lower part of a support shaft (60) having a cross-section in the shape of a "U" is insert-molded and fixed to the central portion of the bulkhead (12d) formed on the upper portion of the body case (12). In this case, a hollow portion (60a) having a screw tap formed therein is formed in the central portion of the support shaft (60), and by fastening a fixing bolt (24) to the hollow portion (60a), the impeller (20) and the rotor support (33) of the rotor (30) can be rotatably supported on the support shaft (60).

[0071] 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.

[0072] Meanwhile, the present invention employs an axial gap type electric motor (200) including a slim stator (40) arranged in a sealed lower space (14) inside the body case (12) and a rotor (30) arranged opposite the stator (40) in a fluid flow passage (P) outside the body case (12) as a driving means for rotating the impeller (20).

[0073] First, the rotor (30) is formed 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) is installed on the back surface of the magnet (32) to form a magnetic circuit.

[0074] The above back yoke (31) may be formed of, for example, a laminate of electrogalvanized steel sheets (EGI steel sheets).

[0075] A thin plate partition (12d) is installed on the upper part of the body case (12) to separate the stator (40) and the rotor (30), thereby enabling a completely waterproof structure for the stator (40). That is, the stator (40) placed in the sealed lower space (14) inside the body case (12) can be completely blocked from contact with water.

[0076] The above bulkhead (12d) is formed with a relatively thin thickness compared to the cylindrical portion of the body case (12), so that the magnet of the rotor (30) can be a ferrite magnet, which is a non-rare earth magnet, as described below.

[0077] That is, the electric motor (200) of the present invention is an axial gap type in which the rotor (30) and the stator (40) face each other with a thin plate partition (12d) therebetween, 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, even if the electric motor (200) according to the present invention is operated for a long time in a state in which the magnet (32) of the rotor (30) is 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 (200) of the present invention can further reduce the air gap and increase efficiency compared to an electric motor that employs a rare earth magnet having a magnet waterproof structure.

[0078] In addition, in the present invention, when applying a longitudinal-axis type motor having the same outer diameter as a general internal-rotor type motor, it is possible to reduce the air gap by separating the magnet of the rotor (30) and the core of the stator (40) using a thin plate partition (12d), 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.

[0079] However, in the present invention, it is also possible to improve the torque of the motor by using a bonded Nd magnet as the magnet of the rotor (30).

[0080] The above support shaft (60) can be integrally formed by insert molding in which a part of the support shaft (60) is inserted into the central portion of the partition wall (12d) during injection molding of the body case (12), or can be fixed by pressing into the support shaft receiving portion (12c) formed integrally in the central portion of the partition wall (12d).

[0081] A portion of the above-mentioned support shaft receiving portion (12c) extends from the bulkhead (12d) to the lower space (14) and has a sufficient contact area to firmly support the lower end of the support shaft (60).

[0082] Hereinafter, a slim stator of an axial gap type motor according to one embodiment of the present invention will be described with reference to FIGS. 7 to 13.

[0083] First, as shown in FIGS. 8 and 9, a laminated printed circuit board (PCB) (50) having a plurality of through holes (51a) formed therein and a back yoke (42) having a plurality of through holes (42a) formed therein are prepared, and then the teeth (41c) of the plurality of split cores (41) are first inserted into the through holes (51a) of the laminated printed circuit board (PCB) (50), and the tip portions of the teeth (41c) protruding from the bottom of the laminated printed circuit board (PCB) (50) are coupled to the through holes (42a) of the back yoke (42), thereby preparing a slim stator (40).

[0084] The above plurality of split cores (41) each have a head (41b) located at the front end and a tooth (41c) extending from the head (41b) to the rear end, and have a cross-section in the shape of the letter “T”, and are positioned so that the shoe (41a), which is the front end surface of the head (41b), is exposed to the fluid flow passage (P).

[0085] The above back yoke (42) forms a magnetic circuit and is composed of a circular body (42c) having a central through hole (42b) formed in the center thereof, and a plurality of through holes (42a) formed at equal intervals in the circular body (42c) into which teeth (41c) of a plurality of split cores (41) are inserted and joined.

[0086] The slim stator (40) of the present invention is assembled and installed in a lower space (14) that maintains a sealing state, and as a result, it is arranged axially opposite to the rotor (30) with a thin plate partition (12d) therebetween, so that an axial gap type motor can be formed.

[0087] In addition, as in the manufacturing method illustrated in Fig. 12, a slim stator (40) may be prepared first, and then integrally formed using an insert molding method during injection molding of the body case (12).

[0088] Furthermore, as in the manufacturing method illustrated in Fig. 13, when the body case (12) is injection-molded, the head (41b) of the split core (41) made of soft magnetic powder (SMC) or silicon steel is integrally formed by insert molding, and in this case, the shoe (41a) of the split core (41) can be positioned so as to be exposed to the fluid flow passage (P).

[0089] In addition, it is also possible to first prepare a body case (12) in which a plurality of through holes (12e) are formed at positions corresponding to the plurality of split cores (41) in the bulkhead (12d), and then assemble and combine a split core (41) made of a soft magnetic powder (SMC) or silicon steel into the through holes (12e) of the body case (12).

[0090] In this case, the head (41b) of the split core (41) is assembled into the through hole (12e) of the body case (12), and the shoes (41a) of the plurality of split cores (41) are positioned so that they are exposed to the fluid flow passage (P), and then the boundary between the shoes (41a) and the through hole (12e) can be waterproofed and sealed using epoxy or urethane.

[0091] Below, the slim stator (40) of the present invention is described in detail.

[0092] The above slim stator (40) uses a laminated printed circuit board (PCB) (50) in which a plurality of coil patterns (U1-U6, V1-V6, W1-W6) are formed by being patterned in a spiral conductive pattern on each layer of a multilayer substrate (51), and a plurality of through holes (51a) are formed inside the plurality of coil patterns (U1-U6, V1-V6, W1-W6). All of the plurality of through holes (51a) may be formed in a triangular or rectangular shape.

[0093] The above slim stator (40) forms a plurality of coil patterns (U1-U6, V1-V6, W1-W6) patterned on a laminated printed circuit board (PCB) (50) of a multilayer substrate, and can easily implement a common electrode terminal (52) that forms a neutral point (COM) for Y-connection required when driving a stator (40) of three U, V, and W coils in a 6-step manner using a printed circuit board (PCB) of a multilayer substrate (51).

[0094] In the present invention, the driver for driving the stator (40) may be placed outside the pump housing (10) to form a slim electric water pump (EWP) (100), or it may be formed integrally with the laminated printed circuit board (PCB) (50).

[0095] The plurality of split cores (41) that are combined by inserting the lower ends of the teeth (41c) into the plurality of through-holes (51a) above each have a head (41b) having a flat tip and a fan-shaped shape, and a tooth (41c) that extends from the head (41b) and protrudes through the through-hole (51a) of the laminated printed circuit board (PCB) (50) in a triangular or rectangular shape corresponding to the through-hole (51a).

[0096] The above plurality of split cores (41) may each be formed of soft magnetic powder (SMC: Soft Magnetic Composites) or may be formed by laminating a plurality of silicon steels.

[0097] The above-described plurality of split cores (41) may each be made of isotropic magnetic materials having high magnetic permeability, low coercivity and high saturation magnetic induction, such as Fe-Ni, Fe-Co, and Fe-Si alloy powders, as soft magnetic powders (SMC). If the split cores (41) are manufactured using compression molding or extrusion molding using such soft magnetic powders (SMC), they can be formed into a 3D structure, and the cores have isotropic properties.

[0098] In the present invention, the split core (41) can be easily manufactured using a soft magnetic powder (SMC), and a “rounding (R)” required for forming a curve can be easily formed in the shoe portion to obtain a back EMF (Back Electromotive Force) waveform of a sine curve to prevent the occurrence of noise and vibration when the rotor of the driving motor rotates.

[0099] The split core (41) of the present invention can be formed by mixing amorphous metal powder with a binder and forming it in addition to compression molding of a soft magnetic powder (SMC), or by mixing amorphous metal powder, spherical soft magnetic powder (SMC), and a binder in a predetermined ratio. In this case, compared to using 100% of the amorphous metal powder, mixing spherical soft magnetic powder (SMC) in a predetermined ratio can resolve the difficulty of high-pressure sintering and increase the permeability.

[0100] In this case, when the plurality of split cores (41) are each made of soft magnetic powder (SMC: Soft Magnetic Composites), the split cores compression-molded with the soft magnetic powder (SMC) do not form rust when in contact with water.

[0101] As a result, when injection molding the above body case (12), a split core (41) made of a soft magnetic powder (SMC) can be formed integrally by insert molding so that the shoe (41a) is positioned so that it is exposed to the fluid flow passage (P).

[0102] In addition, when a split core (41) made of a soft magnetic powder (SMC) is assembled and combined with the body case (12), a plurality of through holes (12e) are formed in the partition wall (12d) of the body case (12) at positions corresponding to the plurality of split cores (41), and after the shoes (41a) of the plurality of split cores (41) are positioned so as to be exposed to the fluid flow passage (P), a waterproof sealing treatment can be performed using epoxy or urethane at the boundary between the shoes (41a) and the through holes (12e).

[0103] In this structure where the shoe (41a) of the plurality of split cores (41) is exposed to the fluid flow passage (P), the gap between the rotor (30) and the stator (40) can be set to a minimum interval of 0.1 to 0.2T, thereby promoting an increase in the efficiency of the motor.

[0104] In this case, if the plurality of split cores (41) are each formed by laminating a plurality of silicon steels, the split cores made of silicon steel may form rust when in contact with water.

[0105] Accordingly, in this case, a plurality of through holes (12e) are formed in positions corresponding to the plurality of split cores (41) in the bulkhead (12d) of the body case (12), and the shoes (41a) of the plurality of split cores (41) are positioned so as to be exposed to the fluid flow passage (P), and then a waterproof sealing treatment can be performed by coating a thin film of epoxy or urethane so that the exposed shoes (41a) and the bulkhead (41d) form the same plane.

[0106] A plurality of teeth (41c) protruding downward through the through-hole (51a) of the laminated printed circuit board (PCB) (50) are coupled to the through-hole (42a) of the back yoke (42) forming the magnetic circuit. In this case, it is preferable to establish an insulating state by inserting insulating paper in advance between the laminated printed circuit board (PCB) (50) and the back yoke (42).

[0107] By fixing the teeth (41c) of the above-described plurality of split cores (41) to the through-holes (42a) of the back yoke (42) by, for example, press-fitting, the slim stator (40) according to the present invention changes from a coreless type to a core type. As a result, the leakage magnetic flux that deviates from the path in the magnetic circuit formed between the coils of the stator (40) and the magnets (32) of the rotor (30) can be minimized, thereby increasing motor efficiency.

[0108] The slim stator (40) of the present invention can form stator coils by patterning a plurality of coil patterns (U1-U6, V1-V6, W1-W6) on a laminated printed circuit board (PCB) (50) of a multilayer substrate (51) without using a bobbin, and when forming a plurality of stator coils using the printed circuit board (PCB) (50), a common electrode terminal (52) forming a neutral point (COM) for Y-connection of the U, V, and W three-phase coils can also be easily implemented.

[0109] As a result, the slim stator (40) of the present invention can realize a slim structure by having a laminated printed circuit board (PCB) (50) of a multilayer substrate (51) compared to a stator using a bobbin coupled to a stator core.

[0110] The electric water pump (100) according to the present invention is driven by an axial gap type motor (200) in a three-phase BLDC manner, and the slots and poles can be configured in a 3:4 or 3:2 ratio. The axial gap type motor (200) can be configured as a BLDC motor having, for example, a 12-pole-9-slot or an 8-pole-6-slot structure. In the case where the motor (200) has an 8-pole-6-slot structure, when the coils of the stator (40) are configured in a series or parallel circuit with six coils in a U, V, W three-phase structure without using a bobbin, the three-phase drive circuit can be easily connected in a Y-connection manner using a laminated printed circuit board (PCB) (50).

[0111] Moreover, the above motor (200) can be driven by a 6-step electric wave driving method using, for example, an inverter circuit (56).

[0112] The above axial gap type motor (200) can detect the rotational position of the rotor (30) by using, for example, a Hall sensor as a rotor position detection element when driven by a three-phase (U, V, W) drive method. To this end, when the rotor (30) rotates, the rotational position of the rotor (30) can be detected by a Hall sensor assembly installed on a laminated printed circuit board (PCB) (50). The rotor position detection element that detects the position signal of the rotor (30) can use, for example, two or three Hall elements in the case of a three-phase drive method. The Hall sensor assembly can have a structure in which three Hall sensors and peripheral circuit elements are mounted on a laminated printed circuit board (PCB) (50).

[0113] Additionally, the above axial gap type motor (200) can of course use a sensorless type motor drive circuit without using a Hall sensor.

[0114] An electric water pump (EWP) (100) using an axial gap type motor according to the first embodiment illustrated in FIG. 2 is assembled such that a slim stator (40) of an axial gap type motor (200) is housed in the lower space (14) of a body case (12) and then an upper cover (13) is coupled to the lower side.

[0115] An electric water pump (EWP) (100) using an axial gap type motor according to a second embodiment of the present invention, as illustrated in FIGS. 5a and 5b, differs from the first embodiment in that a slim stator (40) of the axial gap type motor (200) is formed integrally with a body case (12).

[0116] Accordingly, in the second embodiment, the lower space (14) on the lower side of the body case (12) is omitted, and the upper cover (13) is also omitted.

[0117] A method for manufacturing an electric water pump (EWP) (100) according to a second embodiment of the present invention is described with reference to FIG. 12.

[0118] First, a plurality of coil patterns (U1-U8, V1-V8, W1-W8) are patterned and formed on each layer of a multilayer substrate (51), and the coil patterns of each phase are connected in series or parallel, and a power terminal pin (55c) connected to an inverter circuit (56) is connected to a start line of each phase, and an end line of each phase is commonly connected to a common electrode terminal (52) to form a neutral point (COM) for Y-connection, thereby preparing a laminated printed circuit board (PCB) (50) having a plurality of coils (S11).

[0119] The above multilayer substrate (51) is formed in a ring shape with a central through hole (51b) formed in the center, and a plurality of coil patterns (U1-U8, V1-V8, W1-W8) formed and laminated on each layer of the above multilayer substrate (51) have a through hole (51a) formed inside each coil pattern to which a tooth (41c) of a back yoke (42) is coupled.

[0120] After that, the teeth (41c) of the plurality of split cores (41) are inserted into the through holes (51a) formed in the laminated printed circuit board (PCB) (50), and then the power terminal pin (55c) is assembled to the laminated printed circuit board (PCB) (50), and a stator (40) assembly is prepared in which the back yoke (42) is coupled to the teeth (41c) protruding from the lower side of the printed circuit board (PCB) (50) (S12) (see FIG. 8).

[0121] Next, when the body case (12) is injection-molded using an insert molding method, the stator (40) assembly can be formed integrally with the body case (12).

[0122] In this case, the shoes (41a) of the plurality of split cores (41) can be positioned so that the flat-shaped leading ends are exposed to the fluid flow passage (P). Each of the plurality of split cores (41) can be made of a soft magnetic powder (SMC). The split cores compression-molded with the soft magnetic powder (SMC) do not form rust when in contact with water.

[0123] In addition, the body case (12) surrounding the stator (40) may preferably be formed of an insulating heat-dissipating composite material having both heat dissipation and insulation performance. In this case, the molding material surrounding the stator (40) may also be made of general plastic.

[0124] It is preferable that the above stator (40) has an insulation performance of at least 10Kv or more, and considering the heat dissipation characteristics, it is preferable that the insulating heat dissipation composite material for the body case (12) has a thermal conductivity of 3W / mK or more.

[0125] Considering the above, the insulating heat-dissipating composite used in the present invention may include a polymer matrix that acts as a binder and has a continuous use temperature of 150°C or higher, an insulating heat-dissipating filler made of ceramic added and dispersed to improve thermal conductivity, and reinforcing fibers added to reinforce strength.

[0126] The above polymer matrix may include one compound selected from the group consisting of polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone (PES), polyether imide (PEI), and polyimide, or a mixture or copolymer of two or more compounds.

[0127] In this case, it is preferable that the polymer matrix has a continuous use temperature of 150°C or higher, and for example, polyphenylene sulfide (PPS) can be used.

[0128] Additionally, the insulating heat-dissipating filler may be provided in an amount of 75 to 100 parts by weight per 100 parts by weight of the polymer matrix.

[0129] In addition, the insulating heat-dissipating filler may include at least one selected from the group consisting of magnesium oxide, talc, titanium dioxide, aluminum nitride, silicon nitride, boron nitride, aluminum oxide, silica, zinc oxide, barium titanate, strontium titanate, beryllium oxide, silicon carbide, and manganese oxide.

[0130] The average particle diameter of the above insulating heat-dissipating filler may be 10 nm to 600 μm.

[0131] Moreover, the reinforcing fiber may be provided in an amount of about 30 parts by weight per 100 parts by weight of the polymer matrix, and for example, glass fiber may be used.

[0132] Additionally, the insulating heat-dissipating composite may further include one or more additives selected from the group consisting of dispersants, antioxidants, workability improvers, coupling agents, stabilizers, flame retardants, pigments, and impact improvers.

[0133] The above insulating heat-dissipating composite material can be made of BMC (Bulk Molding Compound), a heat-curable plastic material. BMC is manufactured by first uniformly mixing (compounding) unsaturated polyester resin and fillers using a kneader, and then secondarily impregnating the raw material with 6 mm glass fibers and aging the resulting raw material for a certain period of time.

[0134] A driver may be installed at the bottom of the above stator (40) to generate a rotating magnetic field by applying a driving signal to the three-phase coil of the stator (40), but in the drawing of this embodiment, it is omitted for slimming purposes, and the driver is installed externally.

[0135] Another manufacturing method of an electric water pump (EWP) (100) according to a second embodiment of the present invention is described with reference to FIG. 13.

[0136] First, when injection molding the body case (12), the flat-shaped tip end of the shoe (41a) of the plurality of split cores (41) is positioned so that it is exposed to the fluid flow passage (P) and formed integrally with the body case (12) using an insert molding method (S21).

[0137] After that, a plurality of coil patterns (U1-U6, V1-V6, W1-W6) are patterned and formed on each layer of the multilayer board (51), and the coil patterns of each phase are connected in series or parallel, and a power terminal pin (55c) connected to an inverter circuit (56) is connected to the start line of each phase, and the end line of each phase is commonly connected to a common electrode terminal (52) to form a neutral point (COM) for Y-connection, thereby preparing a laminated printed circuit board (PCB) (50) having a plurality of coils. Then, the teeth (41c) of the plurality of split cores (41) are inserted into the through holes (51a) of the printed circuit board (PCB) (50) and assembled (S22).

[0138] Next, the tip of the tooth (41c) protruding from the lower side of the through hole (51a) of the laminated printed circuit board (PCB) (50) is inserted into the through hole (42a) of the back yoke (42) and joined (S23).

[0139] Finally, the upper cover (13) is assembled to the lower part of the body case (12) (S24).

[0140] In this case, the shoes (41a) of the plurality of split cores (41) compression-molded with soft magnetic powder (SMC) can be positioned so that the flat-shaped leading edge portions are exposed to the fluid flow passage (P).

[0141] Since the split cores compression-molded with the above-mentioned soft magnetic powder (SMC) do not form rust when in contact with water, a structure in which the shoes (41a) of the plurality of split cores (41) are exposed to the fluid flow passage (P) can be adopted, and as a result, the gap between the rotor (30) and the stator (40) can be set to a minimum interval of 0.1 to 0.2T, thereby promoting an increase in the efficiency of the motor.

[0142] Below, a laminated printed circuit board (PCB) (50) is described in detail.

[0143] As illustrated in FIGS. 10a to 10e, a laminated printed circuit board (PCB) (50) according to the present invention uses a multilayer substrate (51) and is formed by patterning a Cu thin film to form a plurality of coil patterns (U1-U8, V1-V8, W1-W8) corresponding to U, V, and W three-phase coils for each layer (50a to 50e), and the plurality of coil patterns (U1-U8, V1-V8, W1-W8) of each of the U, V, and W phases are connected in series with each other, as illustrated in FIG. 11.

[0144] The laminated printed circuit board (PCB) (50) according to the present invention is described as an example of a structure in which five-layer substrates (50a-50e) are laminated.

[0145] In the first to fourth layer substrates (50a-50d) illustrated in FIGS. 10a to 10d, two coil patterns are alternately arranged and interconnected for each of the U, V, and W phases.

[0146] On the first layer substrate (50a), two coil patterns (U1-U2, V1-V2, W1-W2) are alternately arranged for each of the U, V, and W phases, and the coil patterns (U1-U2, V1-V2, W1-W2) of each phase are connected in series with each other.

[0147] In addition, on the second layer substrate (50b), two coil patterns (U3-U4, V3-V4, W3-W4) are alternately arranged for each of the U, V, and W phases, and the coil patterns (U3-U4, V3-V4, W3-W4) of each phase are connected in series with each other.

[0148] Among the two coil patterns (U1-U2, V1-V2, W1-W2) for each of U, V, and W in the first layer substrate (50a), the coil pattern (U1, V1, W1) having a start line (U1S, V1S, W1S) is arranged on the left side and is formed as a spiral conductive pattern rotating clockwise, and the coil pattern (U2, V2, W2) having an end line (U2E, V2E, W2E) is arranged on the right side and is formed as a spiral conductive pattern rotating counterclockwise.

[0149] In addition, among the two coil patterns (U3-U4, V3-V4, W3-W4) for each of U, V, and W in the second layer substrate (50b), the coil pattern (U3, V3, W3) having a start line (U3S, V3S, W3S) is arranged on the right side and is formed as a spiral conductive pattern rotating clockwise, and the coil pattern (U4, V4, W4) having an end line (U4E, V4E, W4E) is arranged on the left side and is formed as a spiral conductive pattern rotating counterclockwise.

[0150] The coil pattern (U3, V3, W3) having the above-mentioned start line (U3S, V3S, W3S) is arranged on the right side so that a series connection is made with the coil pattern (U2, V2, W2) having the end line (U2E, V2E, W2E) arranged on the right side of the first layer substrate (50a), and a conductive via pattern is formed at the point of the end line (U2E, V2E, W2E) and the start line (U3S, V3S, W3S), so that a series connection can be made between the coil pattern (U2, V2, W2) and the coil pattern (U3, V3, W3).

[0151] The above via pattern can be formed as a small-diameter conductive via using a conductive metal material with excellent heat transfer characteristics and conductivity, and can be formed between the first layer substrate (50a) and the second layer substrate (50b) of a multilayer board (PCB) (51).

[0152] In the first layer substrate (50a), a U-phase coil pattern (U1) having a U-phase start line (U1S) and a U-phase coil pattern (U2) having an end line (U2E) are connected in series with each other in the first layer substrate (50a), and the V-phase and W-phase coil patterns (V1, W1) having V-phase and W-phase start lines (V1S, W1S) and the V-phase and W-phase coil patterns (V2, W2) having V-phase and W-phase end lines (V2E, W2E) are connected using a first conductive connection pattern (CL1) printed on the first layer substrate (50a) and second to fourth conductive connection patterns (CL2-CL4) printed on the second layer substrate (50b).

[0153] Among the two coil patterns (U5-U6, V5-V6, W5-W6) for each of U, V, and W in the third layer substrate (50c), the coil pattern (U5, V5, W5) having a start line (U5S, V5S, W5S) is arranged on the left side and is formed as a spiral conductive pattern rotating clockwise, and the coil pattern (U6, V6, W6) having an end line (U6E, V6E, W6E) is arranged on the right side and is formed as a spiral conductive pattern rotating counterclockwise.

[0154] In addition, among the two coil patterns (U7-U8, V7-V8, W7-W8) for each of U, V, and W in the fourth layer substrate (50d), the coil pattern (U7, V7, W7) having a start line (U7S, V7S, W7S) is arranged on the right side and is formed as a spiral conductive pattern rotating clockwise, and the coil pattern (U8, V8, W8) having an end line (U8E, V8E, W8E) is arranged on the left side and is formed as a spiral conductive pattern rotating counterclockwise.

[0155] In the third layer substrate (50c), a U-phase coil pattern (U5) having a U-phase start line (U5S) and a U-phase coil pattern (U6) having an end line (U6E) are connected in series with each other in the third layer substrate (50c), and the V-phase and W-phase coil patterns (V5, W5) having V-phase and W-phase start lines (V5S, W5S) and the V-phase and W-phase coil patterns (V6, W6) having V-phase and W-phase end lines (V6E, W6E) are connected using a sixth conductive connection pattern (CL6) printed on the third layer substrate (50c) and sixth to eighth conductive connection patterns (CL6-CL8) printed on the fourth layer substrate (50d).

[0156] Moreover, the connection between the coil pattern (U4, V4, W4) formed on the second layer substrate (50b) and the coil pattern (U5, V5, W5) formed on the third layer substrate (50c) can be serially connected by a conductive via (Via) connecting the end line (U4E, V4E, W4E) of the coil pattern (U4, V4, W4) and the start line (U5S, V5S, W5S) of the coil pattern (U5, V5, W5).

[0157] As described above, in the present invention, when forming a laminated printed circuit board (PCB) (50) using a laminated substrate of three or more layers, a third layer substrate (50c) and a fourth layer substrate (50d) having the same structure as the first layer substrate (50a) and the second layer substrate (50b) described above can be laminated to increase the coil patterns of each of the U, V, and W phases.

[0158] The fifth layer substrate (50e) illustrated in FIG. 10e is the lowest layer substrate and serves to connect the final end line for the eight coil patterns (U1-U8, V1-V8, W1-W8) formed on the first to fourth layer substrates (50a-50d) to the inverter circuit (56) via the U, V, and W power terminal pins (55c) and to form a common electrode terminal (52) for the most advanced start line for the coil patterns (U1-U8, V1-V8, W1-W8) to form a neutral point (COM) for the Y-connection of the U, V, and W three-phase coils.

[0159] On the fifth layer substrate (50e) above, three conductive connection patterns (CL9-CL11) are formed to connect the start lines of eight coil patterns (U1-U8, V1-V8, W1-W8) connected in series for each of the U, V, and W phases to three U, V, and W power terminal pins (55c).

[0160] One end of the conductive connection pattern (CL9-CL11) is connected to the U, V, W three-phase output terminals (Uout, Vout, Wout) respectively arranged adjacent to the central through hole (51b) of the multilayer substrate (51), and the other end of the conductive connection pattern (CL9-CL11) is connected to the final end line of each U, V, W phase of the serially connected coil patterns (U1-U8, V1-V8, W1-W8), i.e., the end line (U8E) of the U-phase coil pattern (U8), the end line (V8E) of the V-phase coil pattern (V8), and the end line (W8E) of the W-phase coil pattern (W8).

[0161] One end of the U, V, W power terminal pin (55c) is connected to the above U, V, W three-phase output terminals (Uout, Vout, Wout) by soldering, and the other end is connected to the U, V, W three-phase output terminals (Uout, Vout, Wout) of the inverter circuit (56).

[0162] Accordingly, the eight coil patterns (U1-U8, V1-V8, W1-W8) for each phase formed on the first to fourth substrates (50a-50d) are connected to the U, V, W three-phase output terminals (Uout, Vout, Wout) of the inverter circuit (56) through the U, V, W power terminal pins (55c).

[0163] In addition, the fifth layer substrate (50e) of FIG. 10e has a conductive connection pattern (CL12) formed in a curve on the outer surface of the substrate, and the most advanced start lines for the coil patterns (U1-U8, V1-V8, W1-W8), i.e., the start line (U1S) of the U-phase coil pattern (U1), the start line (V1S) of the V-phase coil pattern (V1), and the start line (W1S) of the W-phase coil pattern (W1), can be commonly connected to the conductive connection pattern (CL12) to serve as a common electrode terminal (52).

[0164] In the above-described embodiment, the first to fourth layer substrates (50a-50d) are used to implement eight coil patterns (U1-U8, V1-V8, W1-W8) for each of the U, V, and W phases, and one lowermost layer substrate, i.e., the fifth layer substrate (50e), is used to connect one end of the U, V, W power terminal pin (55c) to the U, V, W three-phase output terminals (Uout, Vout, Wout) of the inverter circuit (56). However, an additional coil pattern connection layer may be further provided to connect the coil patterns (U1-U8, V1-V8, W1-W8) in series or in parallel.

[0165] A plurality of conductive connection patterns (CL1-CL12) for interconnecting the above coil patterns can be modified as needed, and a plurality of conductive vias formed at both ends of the conductive connection patterns (CL1-CL12) can also be modified as needed.

[0166] As described above, the axial gap type motor (200) for the electric water pump (100) according to the present invention has a structure in which the stator (40) is placed in a lower space (14) inside the body case (12), which is a waterproof space completely separated from the fluid flow passage (P) inside the pump cover (11), the rotor (30) is formed integrally with the impeller (20) and placed in the fluid flow passage (P), and the stator (40) and the rotor (30) are separated by a partition (12d).

[0167] In this case, after manufacturing the partition wall (12d) of the body case (12) so that a plurality of through holes (12e) are formed at positions corresponding to the plurality of split cores (41), and then assembling and joining the split cores (41) made of soft magnetic powder (SMC), the shoes (41a) of the plurality of split cores (41) are positioned so that they are exposed to the fluid flow passage (P), and then the boundary between the shoes (41a) and the through holes (12e) can be waterproofed using epoxy or urethane.

[0168] In addition, when the plurality of split cores (41) are each formed by laminating a plurality of silicon steels, the split cores made of silicon steel may form rust when in contact with water.

[0169] Accordingly, in this case, a plurality of through holes (12e) are formed in positions corresponding to the plurality of split cores (41) in the bulkhead (12d) of the body case (12), and the shoes (41a) of the plurality of split cores (41) are positioned so as to be exposed to the fluid flow passage (P), and then a waterproof sealing treatment can be performed by coating a thin film of epoxy or urethane so that the exposed shoes (41a) and the bulkhead (41d) form the same plane.

[0170] In addition, the stator (40) can be manufactured by first forming a plurality of split cores (41) made of soft magnetic powder (SMC) integrally by positioning them on a partition wall (12d) so that the shoe (41a) is exposed to the fluid flow passage (P) using an insert molding method when the body case (12) is injection molded, and then assembling a laminated printed circuit board (50) and a back yoke (42) to the teeth (41c) of the split cores (41).

[0171] Furthermore, in the present invention, a slim stator (40) having a plurality of split cores (41) and a back yoke (42) combined on a laminated printed circuit board (PCB) (50) can be manufactured by insert molding into a body case (12) and integrating them.

[0172] In this case, when insert molding the slim stator (40) into the body case (12), the shoe (41a) of the split core (41) made of soft magnetic powder (SMC) can be positioned so as to be exposed to the fluid flow passage (P) so as to be formed integrally.

[0173] In a structure in which the shoe (41a) of the plurality of split cores (41) is exposed to the fluid flow passage (P) as described above, the gap between the rotor (30) and the stator (40) can be set to a minimum interval of 0.1 to 0.2T, thereby improving the efficiency of the motor.

[0174] When a water pump control signal is applied to the driver from an electric water pump (100) control device inside a vehicle, the driver applies a drive signal to a plurality of coils of the axial gap type motor (200) from the driver when receiving a rotor position signal from a hall sensor (not shown), and a rotating magnetic field is generated in the stator (40) from the plurality of coils.

[0175] When a rotating magnetic field is generated from a plurality of coils of the above stator (40), the rotor (30) placed in the fluid flow passage (P) 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).

[0176] 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 (200) disposed outside the fluid flow passage (P) in a magnetic coupling manner, thereby realizing complete waterproofing of the stator (40) of the electric motor (200).

[0177] Moreover, in the present invention, since the stator (40) of the electric motor (200) 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 (200) can be set to an optimal state, thereby improving the efficiency of the electric motor (200).

[0178] The present invention applies a longitudinal shaft motor having the same outer diameter as an internal combustion motor, so that even if a ferrite magnet, which is a non-rare earth magnet, is used, it can have the same magnetic energy as an electric motor using a rare earth magnet.

[0179] As described above, in the present invention, a plurality of coil patterns (U1-U6, V1-V6, W1-W6) formed by being patterned in a spiral conductive pattern on each layer (50a-50e) of a multilayer substrate (51) as shown in FIGS. 10a to 10e are printed on a laminated printed circuit board (PCB) (50), and a plurality of split cores (41) made of soft magnetic powder (SMC: Soft Magnetic Composites) or formed by laminating a plurality of silicon steels are integrally formed by insert molding them into a body case (12), and then a back yoke (42) that functions as a magnetic circuit and the laminated printed circuit board (PCB) (50) are combined to a tooth (41c) of the split core (41) protruding toward the rear, thereby exposing a shoe (41a) portion of the split core (41) to a fluid flow passage (P), thereby minimizing the air gap and simultaneously reducing the magnetic flux leakage. It is possible to increase the efficiency of the motor by minimizing the occurrence of noise, and to achieve complete waterproofing while significantly reducing the overall height of the pump.

[0180] In addition, in the present invention, a plurality of split cores (41) made of a soft magnetic powder (SMC) or formed by stacking a plurality of silicon steels are inserted into the central portion of each coil of a laminated printed circuit board (PCB) (50), a power terminal pin is assembled to the laminated printed circuit board (PCB) (50), and a stator assembly in which a back yoke (42) is joined to a tooth (41c) of the split core (41) protruding from the rear surface of the laminated printed circuit board (PCB) (50) is insert-molded into the body case (12) to form an integral body, thereby minimizing the air gap and minimizing the generation of magnetic flux leakage by exposing the shoe (41a) of the split core (41) to the fluid flow passage (P), thereby promoting an increase in motor efficiency, and making it possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0181] In this case, it is preferable to insert insulating paper for insulation between the plurality of split cores (41) and the laminated printed circuit board (PCB) (50) and between the laminated printed circuit board (PCB) (50) and the back yoke (42).

[0182] When the above stator assembly is integrated into the body case (12) by insert molding, an insulating heat-dissipating composite material can be used.

[0183] Moreover, in the present invention, a plurality of coils are formed on a laminated printed circuit board (PCB) (50) in which a plurality of coils are formed in a conductive pattern for each layer, and a driving printed circuit board (PCB) having a motor drive circuit implemented thereon is directly connected using a power terminal pin (55c) or a lead wire, one end of which is located inside a connector housing, so that an auxiliary PCB for coil wiring and other additional bus bars can be eliminated.

[0184] In addition, in the present invention, a plurality of split cores (41) made of a soft magnetic powder (SMC) or formed by stacking a plurality of silicon steels are inserted into the central portion of each coil of a laminated printed circuit board (PCB) (50), a power terminal pin (55c) is assembled to the laminated printed circuit board (PCB) (50), and a stator assembly in which a back yoke is joined to the teeth (41c) of the split cores (41) protruding from the rear surface of the laminated printed circuit board (PCB) is molded with an insulating heat-dissipating composite material to form an integral body, and then assembled to a body case (12), thereby minimizing the air gap and minimizing the generation of magnetic flux leakage by exposing the shoe (41a) of the split core (41) to the fluid flow passage (P), thereby promoting an increase in motor efficiency, and making it possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0185] When integrating the above stator assembly by molding, the insulating heat-dissipating composite material may be a BMC (Bulk Molding Compound) material with a heat-dissipating effect among insert molding materials.

[0186] In this case, when the stator assembly is installed in an injection mold and molded with BMC (Bulk Molding Compound), the tip of the teeth (41c) of the split core (41) or a part of the back yoke (42) may be exposed to serve as a position guide during insert molding.

[0187] In addition, in the present invention, when the thin plate partition (12d) formed integrally in the body case (12) between the rotor (30) and the stator (40) is removed and the stator assembly is integrated by insert molding into the body case (12), the air gap is minimized by insert molding into the body case (12) so that the shoe (41a) portion of the split core (41) is exposed to the fluid flow passage (P), and at the same time, the leakage flux is minimized by combining the back yoke (42) with the tooth (41c) of the split core (41), thereby increasing the efficiency of the motor, and it is possible to realize complete waterproofing while significantly reducing the overall height of the pump.

[0188] As a result, the present invention can reduce the air gap, so that even if a ferrite magnet, which is a non-rare earth magnet, is used as the magnet (32) of the rotor (30), a slim axial gap type motor (200) having magnetic energy equivalent to that of a motor using a rare earth magnet containing Nd can be provided. In addition, by using a rare earth magnet containing bonded Nd, the performance of the motor can be increased.

[0189] In addition, in the present invention, a multilayer printed circuit board (PCB) (50) in which a plurality of coils are formed as conductive coil patterns (U1-U8, V1-V8, W1-W8) for each layer of a multilayer substrate (51) is used, and a plurality of split cores (41) made of soft magnetic powder (SMC) or in which a plurality of silicon steels are laminated are inserted into the central portion of each coil pattern (U1-U8, V1-V8, W1-W8), and a back yoke (42) serving as a magnetic circuit is connected to the teeth (41c) of the plurality of split cores (41) protruding from the rear surface of the multilayer printed circuit board (PCB) (50) to form a stator (40), thereby significantly reducing the overall height of the electric water pump (100) from the conventional 40 mm to 17 mm while increasing the efficiency of the motor.

[0190] In addition, in the present invention, a plurality of split cores (41) connected to a back yoke (42) are combined into a plurality of through holes (51a) formed in the central portion of a plurality of coil patterns (U1-U8, V1-V8, W1-W8) of a multilayer substrate (51), thereby minimizing the portion occupied by the gap in the direction of the magnetic field, thereby minimizing the generation of leakage magnetic flux and thus improving the efficiency of the motor.

[0191] Furthermore, in the present invention, a slim stator (40) in which a plurality of split cores (41) and a back yoke (42) are combined on a laminated printed circuit board (PCB) (50) is integrated by insert molding into a body case (12), thereby further reducing the overall height of the electric water pump (100) to 11.9 mm while achieving complete waterproofing.

[0192] 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.

[0193] The present invention relates to an axial gap type electric motor having a plurality of split cores, and in particular, the electric motor can be applied to hybrid, electric and fuel cell vehicles, and can be applied to electric water pumps (EWPs), compressors, oil pumps, etc. for cooling devices that circulate coolant for electrical components, batteries, fuel cell stacks, etc.

Claims

1. A rotor rotatably supported in a fluid flow passage between the pump cover and the body case; and It includes a stator formed integrally with the above body case to generate a rotating magnetic field and drive the rotor to rotate; The above stator A printed circuit board (PCB) in which a plurality of conductive coil patterns in a spiral shape are formed on each layer of a multilayer board and a plurality of through holes are formed in the center of each coil pattern; A plurality of split cores having teeth inserted into the plurality of through holes and positioned so that the shoe portion of the head is exposed to the fluid flow passage; and A back yoke having a through hole that is joined to a tip of the tooth protruding below the through hole of the printed circuit board (PCB); The above split core is an axial gap type motor for an electric water pump made of soft magnetic powder (SMC).

2. In paragraph 1, The above laminated printed circuit board (PCB) is composed of a multilayer substrate in which multiple coil patterns are formed on each layer to form U, V, and W three-phase coils. The above multiple coil patterns are connected in series for each of the U, V, and W phases, and the start line at the top of the multiple coil patterns assigned to each of the U, V, and W phases connected in series is commonly connected to a common electrode terminal to form a neutral point (COM) for Y-connection. An axial gap type motor for an electric water pump, wherein the final end wire among the plurality of coil patterns assigned to each of the U, V, and W phases connected in series is connected to the U, V, and W three-phase output terminals of the inverter circuit through the U, V, and W power terminal pins.

3. In paragraph 1, The above laminated printed circuit board (PCB) A multilayer substrate having multiple coil patterns formed in series for each U, V, and W phase on each layer; and An axial gap type motor for an electric water pump, comprising: a lower substrate having a common electrode terminal to which the start wires of the uppermost ends of each phase, among a plurality of coil patterns assigned to each phase of U, V, W, which are connected in series to form a neutral point (COM) for Y-connection, are commonly connected; and a U, V, W output terminal in which a U, V, W power terminal pin is connected to the final end wire of each phase, among a plurality of coil patterns assigned to each phase of U, V, W, which are connected in series to connect to the U, V, W three-phase output terminals of an inverter circuit; 4. In paragraph 3, The above multilayer substrate A first layer substrate, in which the first coil pattern having a start line among two serially connected coil patterns for each of U, V, and W phases is formed as a spiral conductive pattern that rotates clockwise and is arranged on the left, and the second coil pattern having an end line among the two coil patterns is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the right; A second layer substrate, wherein the third coil pattern having a start line among two serially connected coil patterns for each of U, V, and W phases is formed as a spiral conductive pattern that rotates clockwise and is arranged on the right, and the fourth coil pattern having an end line among the two coil patterns is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the left; A third layer substrate in which the fifth coil pattern having a start line among two coil patterns for each of U, V, and W is formed as a spiral conductive pattern that rotates clockwise and is arranged on the left, and the sixth coil pattern having an end line is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the right; and A fourth layer substrate is provided, wherein the seventh coil pattern having a start line among two coil patterns for each of U, V, and W is formed as a spiral conductive pattern that rotates clockwise and is arranged on the right, and the eighth coil pattern having an end line among the two coil patterns is formed as a spiral conductive pattern that rotates counterclockwise and is arranged on the left; Axial gap type motor for electric water pumps, with two coil patterns alternately arranged for each of the U, V, and W phases per layer.

5. In paragraph 1, The above split core is an axial gap type motor for an electric water pump having a cross section in the shape of a “T”.

6. In paragraph 1, The above split core is A head having a flat tip and a fan-shaped shape; and It includes teeth that extend from the head and have a triangular or rectangular shape corresponding to the through-hole of the laminated printed circuit board (PCB); An axial gap type motor for an electric water pump, wherein the head is arranged on the front surface of the laminated printed circuit board (PCB), and the teeth pass through the through-hole of the laminated printed circuit board (PCB) and then the tip end is joined to the through-hole of the back yoke.

7. A rotor rotatably supported in the fluid flow passage between the pump cover and the body case; A stator arranged in a lower space formed by the body case and the upper cover to generate a rotating magnetic field and drive the rotor to rotate; and A bulkhead is disposed on the upper part of the body case to separate the rotor and the stator; The above stator A plurality of split cores having a head integrally formed with the baffle so that the cross-section is formed in a “T” shape and the shoe portion is exposed to the fluid flow passage; A printed circuit board (PCB) in which a plurality of conductive coil patterns in a spiral shape are formed on each layer of a multilayer board, a plurality of through holes are formed in the center of each coil pattern, and the teeth of the split core are inserted into the through holes; and An axial gap type motor for an electric water pump (EWP), comprising a back yoke having a through hole that is coupled with a tip end of the tooth protruding below the through hole of the printed circuit board (PCB).

8. In paragraph 7, The bulkhead of the above body case has a plurality of through holes at positions corresponding to the plurality of split cores, An axial gap type motor for an electric water pump, wherein the heads of the plurality of split cores coupled to the plurality of through holes are positioned so that the shoes are exposed to the fluid flow passage, and the split cores are made of a soft magnetic powder (SMC).

9. In paragraph 7, The bulkhead of the above body case has a plurality of through holes at positions corresponding to the plurality of split cores, An axial gap type electric motor for an electric water pump, wherein the heads of the plurality of split cores coupled to the plurality of through holes are positioned so that the shoes are exposed to the fluid flow passage, the split cores are formed by laminating silicon steel, and the exposed shoes and the bulkheads are waterproof-sealed to form the same plane.

10. A pump housing having a pump cover having an inlet for introducing fluid and an outlet for discharging the introduced fluid, and a body case coupled to the lower portion of the pump cover to form a fluid flow passage between the inlet and the outlet; A rotor rotatably supported in the above fluid flow passage; An impeller formed integrally with the rotor on the upper side of the rotor; and It includes a stator formed integrally with the above body case to generate a rotating magnetic field and drive the rotor to rotate; The above stator A printed circuit board (PCB) in which a plurality of conductive coil patterns in a spiral shape are formed on each layer of a multilayer board and a plurality of through holes are formed in the center of each coil pattern; A plurality of split cores having teeth inserted into the plurality of through holes and positioned so that the shoe portion of the head is exposed to the fluid flow passage; and A back yoke having a through hole that is joined to a tip of the tooth protruding below the through hole of the printed circuit board (PCB); The above split core is an electric water pump made of soft magnetic powder (SMC).

11. In paragraph 10, The above plurality of split cores are each formed integrally with a baffle for separating the rotor and the stator, and are positioned on the upper part of the body case so that the shoe portion of the head is exposed to the fluid flow passage. An electric water pump in which the printed circuit board (PCB) is assembled so that the teeth are inserted into a plurality of through holes of each coil pattern.

12. In paragraph 10, The above laminated printed circuit board (PCB) is composed of a multilayer substrate in which multiple coil patterns are formed on each layer to form U, V, and W three-phase coils. The above multiple coil patterns are connected in series for each of the U, V, and W phases, and the start line at the top of the multiple coil patterns assigned to each of the U, V, and W phases connected in series is commonly connected to a common electrode terminal to form a neutral point (COM) for Y-connection. An electric water pump in which the final end wire among the plurality of coil patterns assigned to each of the U, V, and W phases connected in series is connected to the U, V, and W three-phase output terminals of the inverter circuit through the U, V, and W power terminal pins.

13. In paragraph 10, The above laminated printed circuit board (PCB) A multilayer substrate having multiple coil patterns formed in series for each U, V, and W phase on each layer; and An electric water pump comprising: a lower substrate having a common electrode terminal to which the start wires of the uppermost ends of each phase, among a plurality of coil patterns assigned to each phase of U, V, W, which are connected in series to form a neutral point (COM) for Y-connection, are commonly connected; and a U, V, W output terminal to which the U, V, W power terminal pins are connected to the final end wires of each phase, among a plurality of coil patterns assigned to each phase of U, V, W, which are connected in series to connect to the U, V, W three-phase output terminals of an inverter circuit.

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