Water pump using axial gap-type motor

Abstract

The present invention relates to a water pump using an axial gap-type motor, wherein stator cores (teeth) are formed using laminated cores to minimize core losses caused by eddy currents, thereby improving the efficiency of the motor. The water pump (EWP) of the present invention comprises: a pump housing; an electric motor having a rotor and a stator; and a waterproof partition wall for separating the rotor and the stator inside the pump housing. The stator cores of the stator comprise: a plurality of divided teeth arranged annularly on the same circumference in parallel to the axial direction so as to face magnets of the rotor, the front end of each tooth being embedded in the waterproof partition wall; and an annular back yoke connected perpendicularly to the rear ends of the plurality of divided teeth so as to form magnetic circuits.

Description

Water pump using an axial gap type motor

[0001] The present invention relates to an axial gap type electric motor, and more particularly, to a water pump using an axial gap type electric motor that can minimize core loss due to eddy current by forming a stator core (teeth) using a laminated core 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.

[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] Accordingly, the present invention has been designed in consideration of such conventional problems, and its purpose is to provide a water pump using an axial gap type motor that can minimize core loss due to eddy current by forming a stator core (teeth) using a laminated core in an axial gap type motor that separates the rotor and the stator using a waterproof partition, thereby increasing the efficiency of the motor.

[0012] Another object of the present invention is to provide a water pump using an axial gap type electric motor that can use a ferrite magnet, which is a non-rare earth magnet, by minimizing the air gap by separating the rotor and the stator using a thick waterproof baffle and waterproofing the surface of the stator core facing the rotor with an ultra-thin waterproof coating film.

[0013] According to one embodiment of the present invention, a water pump (EWP) comprises: a pump housing having a sealed lower space on one side and an inlet for introducing fluid and an outlet for discharging the introduced fluid connected to each other through a fluid flow passage; an electric motor having a rotor rotatably supported in the fluid flow passage and a stator disposed in the lower space for generating a rotating magnetic field to rotate the rotor; and a waterproof partition disposed inside the pump housing for separating the rotor and the stator; wherein the stator cores of the stator are arranged in an annular shape parallel to the axial direction on the same circumference so as to face the magnets of the rotor, and a plurality of split teeth having front ends embedded in the waterproof partition; and an annular back yoke connected to rear ends of the plurality of split teeth at right angles to form a magnetic circuit, wherein each of the plurality of split teeth comprises: a coil winding portion on which the coil is wound; And it includes a shoe having an exposed plane disposed on the upper part of the coil winding section and a pair of extended inclined planes with flanges extending from the exposed plane to both sides, and a waterproof coating film made of a thinner film than the waterproof bulkhead is formed on the exposed plane of the shoe, and the pair of extended inclined planes are embedded in and supported by the waterproof bulkhead, and the waterproof bulkhead and the waterproof coating film form a plane at the same level.

[0014] In this case, the waterproof coating film formed on the exposed plane of the shoe may be formed in advance before the tip portions of the plurality of split teeth are embedded in the waterproof bulkhead by an insert molding method, or the waterproof coating film formed on the exposed plane of the shoe may be formed simultaneously with the formation of the waterproof bulkhead when the tip portions of the plurality of split teeth are embedded in the waterproof bulkhead by an insert molding method.

[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 magnet.

[0016] In this case, the plurality of split teeth may be formed as a laminated core by laminating a plurality of thin film iron sheets formed in a 'T' shape by punching an electrical steel plate of S18, and the back yoke may be formed as a laminated core by laminating a plurality of thin film iron sheets formed in an annular shape by punching an electrical steel plate of S60.

[0017] The plurality of thin film iron pieces forming the plurality of split teeth 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, the body having 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.

[0018] In addition, the stator includes a stator core having a plurality of split teeth and a back yoke interconnected with the plurality of split teeth to form a magnetic circuit; a plurality of bobbins made of an insulating material integrally formed to surround an outer circumferential surface on which a coil of each of the plurality of teeth is wound; and a coil wound on the outer circumferential surface of the bobbin; wherein the plurality of bobbins each have a coil winding body having a through hole formed in the center into which a coil winding part of the tooth is inserted and a coil wound on the outer circumference thereof; and upper and lower flanges are formed at both ends of the body to define an area on which the coil is wound, and the upper and lower flanges are formed in a trapezoidal shape whose width narrows toward the center, and a shoe insertion portion into which a bottom surface of a shoe of the tooth is inserted may be formed around an inlet of the body.

[0019] Moreover, the pump housing includes a pump cover having an inlet for introducing fluid on one side and an outlet for discharging the introduced fluid on the other side; a body case coupled to the pump cover to form a fluid flow passage inside the pump cover and having a lower space; an upper cover coupled to a lower end of the body case to seal the lower space; and a waterproof partition disposed on an upper end of the body case to separate the rotor and the stator; wherein the water pump further includes a support shaft receiving portion integrally formed to extend in the direction of the lower space at the center of the waterproof partition and having first-stage to third-stage grooves formed at the center; a support shaft having a lower end supported in the third-stage groove of the support shaft receiving portion; a sleeve bearing coupled to an outer periphery of the support shaft to rotatably support the rotor and having a lower end supported in the second-stage groove; and a bearing housing receiving the sleeve bearing and having a lower end inserted into the first-stage groove; wherein the rotor support, which is integrally formed on a lower plate of the impeller and receives the rotor therein, may have a bearing housing connected to a central portion thereof.

[0020] In this case, the inner circumference of the cylindrical portion of the body case further includes a plurality of fixing screws or fixing bolt fastening fixing projections that are protruded and formed corresponding to the number of the plurality of split teeth of the stator, and some of the plurality of fixing screws or fixing bolt fastening fixing projections are used to fix the back yoke of the stator core, and the remaining fixing projections can be used to fix a printed circuit board (PCB) of a driver for driving the motor.

[0021] In general, it is difficult for SMC (Soft Magnetic Composites) type stator cores to avoid increased core loss due to eddy current.

[0022] As described above, in the present invention, a laminated core is used to form a stator core in an axial gap type motor that separates the rotor and the stator using a waterproof partition, thereby minimizing core loss due to eddy current and thereby increasing the efficiency of the motor.

[0023] In addition, 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.

[0024] 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.

[0025] 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 bulkhead structure, making it possible to use a ferrite magnet with a relatively low magnetic density compared to a rare earth magnet.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Figure 2 is a front view of the water pump illustrated in Figure 1.

[0031] Figures 3 and 4 are a cross-sectional view taken along line AA (with the pump cover removed) and a cross-sectional view taken along line BB of Figure 2, respectively.

[0032] 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.

[0033] 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.

[0034] FIGS. 8A and 8B are perspective views of a stator and an assembly of a split core and a bobbin with the back yoke removed, respectively, according to one embodiment of the present invention.

[0035] FIGS. 9A to 9D are a perspective view, a longitudinal perspective view, an exploded view, and a perspective view of a split core, respectively, showing an assembly of a laminated split core and a bobbin according to one embodiment of the present invention.

[0036] FIG. 9e is a plan view showing a thin film iron sheet used in a laminated split core according to one embodiment of the present invention.

[0037] Hereinafter, a preferred embodiment according to the present invention will be described with reference to the attached drawings.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] Referring to FIGS. 1 to 6, 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).

[0047] 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) outside 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).

[0048] The above pump cover (11) and body case (12) are preferably formed in a cylindrical shape and have a mutually fixed joint structure.

[0049] 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).

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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).

[0055] 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).

[0056] 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).

[0057] 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 of a narrow upper and lower plate 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). Therefore, 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.

[0058] 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).

[0059] 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.

[0060] 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).

[0061] 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 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.

[0062] 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).

[0063] 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).

[0064] 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).

[0065] 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.

[0066] 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.

[0067] 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).

[0068] 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).

[0069] 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).

[0070] 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).

[0071] The air gap of the present invention 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.

[0072] As a result, in the present invention, a waterproof coating film (14) is formed 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), so that the magnet of the rotor (30) can be a ferrite magnet, which is a non-rare earth magnet, as described below.

[0073] That is, 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.

[0074] 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.

[0075] 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).

[0076] Below, a stator of an axial gap type motor according to one embodiment of the present invention is described.

[0077] 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.

[0078] 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).

[0079] In this case, the plurality of split teeth (41) of the stator core (45) are arranged so that each tip portion faces the magnet (32) of the rotor (30) and are embedded in the waterproof bulkhead (16) of the body case (12).

[0080] In addition, an ultra-thin waterproof coating film (14) is formed on the exposed plane (414a) of the shoe (412) at the tip end of the plurality of split teeth (41) embedded in the waterproof bulkhead (16), so that even if the waterproof bulkhead (16) is formed as a thick film, an ultra-thin waterproof coating film (14) is formed on the exposed plane (414a) of the shoe (412) facing the magnet (32) of the rotor (30), so that it is possible to reduce the air gap compared to the conventional structure in which the tip end of the teeth is arranged on the rear side of the waterproof bulkhead.

[0081] The above-mentioned plurality of split teeth (41) are prepared by forming a plurality of thin film iron pieces (41a) in a "T" shape as shown in Fig. 9e by punching a thin film electrical steel plate (silicon steel), and then, as shown in Fig. 9d, by laminating a plurality of thin film iron pieces (41a) in a "T" shape at a preset thickness.

[0082] The above-described plurality of thin film iron sheets (41a) each include a rectangular body (410a) having a preset width and length, and a pair of flange portions (412b, 412c) extending perpendicularly from both upper sides of the body (410a) so that the width thereof gradually narrows. In this case, the body (410a) has a rectangular shape in which both sides in the longitudinal direction are parallel, and the upper side (412a) and the lower side are also parallel, and the pair of flange portions (412b, 412c) each have a lower side extending perpendicularly from the body (410a) and an upper side (412a) inclined from the upper side (412a) of the body (410a) so that the width thereof gradually narrows.

[0083] The plurality of split teeth (41) formed by laminating the plurality of thin film iron sheets (41a) in a preset thickness form an overall “T” shape, each having a rectangular cross section and including a coil winding part (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 part (410) to expand to a larger area than the coil winding part (410) and opposes the magnet (32) of the rotor (30).

[0084] The above-described plurality of split teeth (41) include, as illustrated in FIG. 9d, a coil winding portion (410) on which the coil (44) is wound; and an exposed plane (414a) disposed on the upper end of the coil winding portion (410) and a shoe (412) having a pair of extended inclined surfaces (414b, 414c) on the front surface with flanges extending from the exposed plane (414a) on both sides.

[0085] In this case, 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).

[0086] 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 split teeth (41) are prevented from being separated by the magnetic force of the magnet (32) of the rotor (30).

[0087] To this end, the shoe (412) is formed with flanges extending to both sides, and is provided with an exposed plane (414a) located at the center of the tip and parallel to the lower end of the coil winding portion (410), and a pair of extended inclined planes (414b, 414c) extended from the exposed plane (414a) to form an inclined plane.

[0088] In this case, 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), 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).

[0089] 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 a thin electrical steel plate (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.

[0090] The outer circumference of the above-mentioned annular body (42a) has a plurality of protrusions (42d), for example, three, protruding, and a through hole formed in each of the three protrusions (42d) is used when fixing the back yoke (42) by fastening a fixing screw or fixing bolt to the through hole of the fixing protrusion (12f).

[0091] 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).

[0092] The above plurality of bobbins (43) each have a through hole (432) formed in the center 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. A shoe insertion part (433) into which the bottom surface of the shoe (412) of the tooth (41) is inserted is provided around the entrance of the body (430).

[0093] 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.

[0094] 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.

[0095] 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.

[0096] As illustrated in Fig. 3, 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).

[0097] 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).

[0098] The assembly of the stator according to the present invention is performed as follows.

[0099] First, for example, a thin film of non-oriented electrical steel (silicon steel) of 0.3 to 0.5T is used, and a plurality of thin film iron sheets (41a) having a "T" shape are formed by punching and preparing them using S18 having a relatively higher silicon content than S60, and then a plurality of split teeth (41) having a longitudinal cross section in a "T" shape are manufactured by laminating them in a preset thickness. 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).

[0100] After that, an epoxy is coated on the exposed surface (414a) of the shoe (412) facing the magnet (32) of the rotor (30) to a thickness of, for example, 0.2 mm to form an ultra-thin waterproof coating film (14).

[0101] 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) by one turn and fixed, and then the ends of the start line and end line are aligned at a certain interval and extended to a predetermined length.

[0102] Next, a plurality of split teeth (41) having an ultra-thin waterproof coating film (14) formed on the exposed plane (414a) of the 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 only a pair of extended inclined surfaces (414b, 414c) of the shoe (412) of the teeth (41) are insert-molded on the waterproof bulkhead (16), thereby forming the body case (12).

[0103] 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.

[0104] 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).

[0105] 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.

[0106] 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.

[0107] 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. 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).

[0108] 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. In this case, when joining the lower part of the coil winding part (410) to the assembly hole (42c) of the back yoke (42) formed by laminating a non-oriented electrical steel (silicon steel) of a thin film of S60, the bobbin (43) serves as a stopper that determines the assembly depth.

[0109] 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).

[0110] 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 connected to the motor drive circuit of the printed circuit board (PCB) (51).

[0111] 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.

[0112] 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).

[0113] In the present invention, a plurality of split teeth (41) of a stator (40) facing a magnet (32) of a rotor (30) are formed of a laminated core formed by punching and laminating a thin electrical steel plate (silicon steel plate), and an ultra-thin waterproof coating film (14) is formed on an exposed plane (414a) of a shoe (412), which is insert-molded between a waterproof bulkhead (16) of a thick film of a body case (12).

[0114] 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 magnet (32) and the tooth (41) having an open structure without requiring a magnetic waterproof structure.

[0115] 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.

[0116] 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 forms a stator core (teeth) (45) using a laminated core, thereby minimizing core loss due to eddy current and thereby increasing the efficiency of the motor.

[0117] 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).

[0118] 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).

[0119] 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 electric motor (100).

[0120] 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).

[0121] 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.

[0122] 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 pump housing having a sealed lower space on one side and an inlet for introducing fluid on the other side and an outlet for discharging the introduced fluid connected through a fluid flow passage; An electric motor having a rotor rotatably supported in the fluid flow passage and a stator disposed in the lower space to generate a rotating magnetic field to rotate the rotor; and A waterproof bulkhead is disposed inside the pump housing to separate the rotor and the stator; The stator core of the above stator is arranged in an annular shape parallel to the axis on the same circumference so as to be arranged so as to face the magnets of the rotor, and includes a plurality of split teeth having a front end embedded in the waterproof bulkhead; and an annular back yoke which is connected to the rear end of the plurality of split teeth at right angles to form a magnetic circuit. The above plurality of split teeth each include a coil winding portion on which the coil is wound; and a shoe having an exposed plane disposed on the upper end of the coil winding portion and a pair of extended inclined surfaces formed by extending flanges on both sides from the exposed plane; A waterproof coating film made of a thinner film than the waterproof bulkhead is formed on the exposed plane of the above shoe, and the pair of extended sloped surfaces are embedded in and supported by the waterproof bulkhead. The above waterproof bulkhead and waterproof coating film form a plane at the same level as the water pump.

2. In paragraph 1, A water pump in which the waterproof coating film formed on the exposed plane of the shoe is formed in advance before the tip portions of the plurality of split teeth are formed by insert molding into the waterproof bulkhead.

3. In paragraph 1, A water pump in which the waterproof coating film formed on the exposed plane of the shoe is formed simultaneously with the formation of the waterproof bulkhead when the tip portions of a plurality of split teeth are formed by insert molding into the waterproof bulkhead.

4. In paragraph 1, A water pump in which 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 magnet.

5. In paragraph 1, The above-mentioned plurality of split teeth are each formed by a laminated core formed by laminating a plurality of thin-film iron sheets in a 'T' shape formed by punching an S18 electrical steel plate, The above back yoke is a water pump made of a laminated core formed by laminating a plurality of thin-film iron sheets in an annular shape formed by punching an S60 electrical steel plate.

6. In paragraph 5, The plurality of thin film iron pieces forming the plurality of split teeth 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 water pump in which each of the above pair of flange parts has 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.

7. In paragraph 1, The above stator A stator core having a plurality of split teeth and a back yoke interconnected with the plurality of split teeth to form a magnetic circuit; A plurality of bobbins made of insulating material integrally formed to surround the outer surface on which each of the plurality of teeth coils is wound; and A coil wound on the outer surface of the above bobbin; The above plurality of bobbins are each A coil winding body having a through hole formed in the center into which a coil winding part of a tee 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 trapezoidal shape with the width narrowing toward the center. A water pump having a shoe insert formed around the entrance of the above body, into which the bottom of the shoe of the tooth is inserted.

8. In paragraph 1, The above pump housing A pump cover having an inlet for introducing fluid on one side and an outlet for discharging the introduced fluid on the other side; A body case having a lower space and being combined with the above pump cover to form a fluid flow passage inside the pump cover; An upper cover that is coupled to the lower part of the body case and sets the lower space in a sealed state; and A waterproof bulkhead is disposed on the upper portion of the body case to separate the rotor and the stator; The above water pump A support shaft receiving portion formed integrally extending in the direction of the lower space at the center of the above waterproof bulkhead and having first to third stage grooves formed at the center; A support shaft whose lower end is supported in the third groove of the support shaft receiving portion; A sleeve bearing that is coupled to the outer periphery of the support shaft to rotatably support the rotor and has a lower end supported by the second stage groove; and Further comprising a bearing housing that accommodates the sleeve bearing and has a lower end inserted into the first stage groove; A water pump having a rotor support integrally formed on the lower plate of the impeller and housing the rotor therein, and having a bearing housing connected to the central portion.

9. In paragraph 8, The inner circumference of the cylindrical portion of the above body case further includes a plurality of fixing screws or fixing bolt fastening projections formed protruding corresponding to the number of the plurality of split teeth of the above stator, A water pump in which some of the plurality of fixing screws or fixing bolt fastening fixing protrusions are used to fix the back yoke of the stator core, and the remaining fixing protrusions are used to fix the printed circuit board (PCB) of the driver for driving the motor.

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