Engine and the fuel pump using the engine
By increasing winding space and improving insulation in brushless motors with internal rotors, the design addresses size and efficiency challenges, resulting in a more efficient and compact fuel pump.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- AISAN IND CO LTD
- Filing Date
- 2007-02-01
- Publication Date
- 2026-05-13
AI Technical Summary
Existing brushless motors with internal rotors face challenges in efficiently winding coils due to limited winding space, leading to potential insulation faults and reduced efficiency, while conventional fuel pumps using these motors suffer from size constraints.
The design incorporates a stator core with radially arranged coil cores and insulators that increase winding space by positioning the inner edge of the outer core radially outside the imaginary straight line connecting the ends, allowing for a higher number of turns and improved insulation, thus reducing motor size and enhancing efficiency.
This configuration increases winding space, prevents insulation faults, and improves motor efficiency, enabling a smaller fuel pump design without compromising magnetic performance.
Smart Images
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Abstract
Description
[0001] The present invention relates to a brushless motor with an internal rotor and a fuel pump that uses this motor.
[0002] A conventional fuel pump that uses a brushless motor with an internal rotor as its drive source is disclosed (compare, for example, JP 2005-110478A corresponding to US 2005 / 0074343A1, JP 2005-110477A). In the brushless motor, no loss problems similar to those in a brushed motor arise due to frictional resistance between a commutator and a brush, electrical resistance between the commutator and the brush, and flow resistance acting upon slots provided for segmenting the commutator. As a result, the motor efficiency of the brushless motor is higher than that of the brushed motor, thus improving the efficiency of the fuel pump. The efficiency of the fuel pump is given by (motor efficiency) x (pump efficiency).If I represents a drive current supplied to the fuel pump motor, V represents an applied voltage, T represents a torque of the motor, N represents a speed of the motor, P represents the pressure of the fuel pumped by the fuel pump, and Q represents a fuel pump size, then the motor efficiency and the pump efficiency can be described as (motor efficiency) = (T × N) / (I × V) and (pump efficiency) = (P × Q) / (T × N). Therefore, (fuel pump efficiency) = (motor efficiency) × (pump efficiency) = (P × Q) / (I × V).
[0003] Then the fuel pump using the brushless motor can be reduced in size, since the size of the motor can be reduced for the equivalent motor efficiency in a case where a brushless motor is used instead of the brushed motor.
[0004] Document US 2004 / 015287 A1 discloses an electric motor whose stator consists of six sectors, each with inwardly facing teeth. A coil former is arranged on each tooth. The winding is arranged on the coil former, which has flat flanges. A tooth-facing side of a coil winding surface on the coil former and the inner edge surface of the yoke section belonging to each sector are located outside a straight line that uses the ends of the yoke's inner surface of the sector.
[0005] The publication EP 0 871 282 A1 discloses a further electric motor comprising a coil core with a wound coil former on it. The side of the coil former facing the outer edge of the core extends along an imaginary line connecting the inner ends of the yoke portion of the coil core. The side of the inwardly facing surface of the yoke portion of the coil core facing the tooth is concave near the edge.
[0006] Document DE 19857954 A1 discloses another electric motor in which the pole stator is composed of several circular ring segments.
[0007] The inventors of the present application have studied a structure for a brushless motor with an internal rotor to easily wind a coil winding wire with a high space factor within a limited winding space of each coil core. This is achieved by reducing the size of the motor through the use of a stator core, by surrounding an outer edge of the rotor with a plurality of coil cores arranged radially. The space factor is the ratio of the cross-sectional area of the winding wire to the winding space. That is, a higher space factor allows for an increased number of turns of the winding wire within the winding space, thus reducing the size of the motor and improving its efficiency.
[0008] With a coil core 300, which forms a stator core and as in Fig. As shown in Figure 9, an inner edge surface 305 of an outer edge core 304 extends circumferentially around a radially outer side of a tooth 302 of the coil core 300 and is generally positioned on an imaginary straight line 330 passing through ends in the circumferential direction of the inner edge surface 305. A side of a coil winding surface 312 of an insulator 310, on or around which a coil 320 is wound, facing the outer edge core 304, extends along the imaginary straight line 330. If the side of the coil winding surface 312 of the insulator 310 facing the outer edge core 304 extends along the imaginary straight line 330, as described above, the winding wire can be easily wound in the winding spaces of the insulator 310 from openings in the insulator 310.
[0009] In a coil core 300, which forms a stator core and as in Fig. As shown in Figure 9, the inner edge surface 305 of an outer edge core 304 is a flat surface, and the outer edge core 304 extends circumferentially around a radially outer side of a tooth 302. Furthermore, an imaginary straight line 330, connecting ends in the circumferential direction of the inner edge surface 305, is arranged on the inner edge surface 305. A side of the coil winding surface 312 of the insulator 310, on which a coil 320 is wound, facing the outer core 304, is a flat surface along the imaginary straight line 330. If the coil winding surface 312 of the insulator 310 on the side of the outer core 304 is the flat surface along the imaginary straight line 330, as described above, the winding wire can easily be wound in the winding spaces of the insulator 310 from openings in the insulator 310.
[0010] However, if the winding wire in the limited winding space is restricted by a predetermined number of turns, the coil 320 can extend close to the opening of the insulator 310. This means that adjacent coils may be positioned close together or, due to the reduced size of the motor, may even touch. Consequently, an insulation fault can occur between these coils. Furthermore, it can be assumed that to improve the motor's efficiency, the number of turns of the winding wire will be increased, requiring a larger winding space. Therefore, it is necessary to reduce the size of the motor while simultaneously increasing the winding space for the winding wire.
[0011] The present invention was made to solve the disadvantages described above, which is why the present invention is based on the objective of providing a motor that has an increased winding space while reducing the size of the motor, and also providing a fuel pump that uses this motor.
[0012] This problem is solved by a motor as specified in claim 1.
[0013] An advantageous embodiment is specified in the dependent patent claim.
[0014] Furthermore, a fuel pump is also provided, comprising the engine described above and a pump driven by the engine, wherein the pump receives (lets in) fuel and increases the pressure of the fuel.
[0015] The invention, along with its additional tasks, features, and advantages, will become clear with reference to the following description of the attached patent claims and the accompanying drawing. These show: Fig. 1A a sectional view illustrating a coil core and an insulator according to a first unclaimed example, Fig. 1B a motor with one rotor removed, viewed longitudinally from one end, Fig. 2 a sectional view showing a fuel pump according to the present unclaimed example, Fig. 3A an explanatory view illustrating a winding process of a coil, Fig. 3B a partial section view of Fig. 3A, viewed from direction IIIB, Fig. 4 a sectional view showing a coil core and insulators according to a second unclaimed example, Fig. 5 a sectional view showing a coil core and an insulator according to a third unclaimed example, Fig. 6A a sectional view showing a coil core and an insulator according to an exemplary embodiment, Fig. 6B a motor with one rotor removed, viewed longitudinally from one end, Fig. 7 a sectional view showing a fuel pump according to the exemplary embodiment, Fig. 8A an explanatory diagram illustrating a winding process of a coil, Fig. 8B a partial section view of Fig. 8A, viewed from direction VIIIB, and Fig. Figure 9 shows a sectional view illustrating a coil core and an insulator according to the state of the art.
[0016] An embodiment of the present invention and several unclaimed examples are described below with reference to the drawings. First unclaimed example
[0017] A fuel pump that uses an engine according to a first unclaimed example is in Fig. 2 shown. A fuel pump 10 according to the present unclaimed example is, for example, a turbine pump of the tank-mounted type, which is located in a fuel tank of a two-wheeled vehicle with a displacement of 150 cm3 or less.
[0018] The fuel pump 10 comprises a pump 12 and a motor 14, which rotates to drive the pump 12. The fuel pump 10 housing is constructed from housings 16 and 18. Each housing 16 and 18 is cylindrically formed by pressing sheet steel, and housing 18 is press-fitted into and attached to housing 16. Housing 16 also serves as a housing for the pump 12 and the motor 14 and is designed to have a thickness of approximately 0.5 mm. Both longitudinal end sections of housing 16 caulk a pump housing 20 and a stator core 30 to secure them. A pump housing 22 and the stator core 30 are pressed against the longitudinal ends of housing 18 such that their longitudinal positions are determined.
[0019] The pump 12 is a turbine pump with pump housings 20 and 22 and an impeller 24. The pump housing 22 is press-fitted into the housing 16 and is pressed against the housing 18 in the longitudinal direction.
[0020] The pump housings 20 and 22 are pump housings in which the impeller 24 is mounted as a rotatable component. A C-shaped pump channel 202 is provided at each free space between the impeller 24 and each of the pump housings 20 and 22. The pressure of a fuel, which is drawn in or introduced via an inlet port 200 provided on the pump housing 20, is increased in the pump channel 202 by the rotation of the impeller 24, whereupon the fuel is pumped to the engine 14. The fuel pumped to the engine 14 flows through a fuel channel 204, which is arranged between the stator core 30 and a rotor 60, and is then supplied to an internal combustion engine via an exhaust port 206.
[0021] Motor 14 is a so-called brushless motor of an internal rotor design. Motor 14 has a stator core 30, insulators 40, and coils 48. As shown in Fig. As shown in Figure 1, the stator core 30 is constructed from six coil cores 32, each separate and arranged circumferentially at regular intervals. The coil core 32 is formed by mutually crimping magnetic steel sheets stacked longitudinally. The coil core 32 has a radially extending tooth 34 and an outer rim core 36 extending in both circumferential directions from a radially outer side of the tooth 34. The outer rim core 36 has a uniform thickness and an arc shape. One side of an inner rim surface 37 of the outer rim core 36, on the side of the tooth 34, is positioned radially outside the imaginary straight line 100 that connects the ends in the circumferential direction of the inner rim surface 37.
[0022] A pair of insulators 40, formed such that they have essentially the same shape, are equipped with a corresponding coil core 32 at both longitudinal ends, so that the pair of insulators is attached to the coil core 32. Each insulator 40 has an inner rim (collar) 42 on its radially inner side and outer rims 44 on a radially outer side thereof to form a winding space defined between the inner rim 42 and the outer rim 44, as shown in Fig. Figure 1A shows, for example, that the inner rings 42 and the outer rings 44 are provided on circumferentially opposite sides of the tooth 34, as shown in Fig. Figure 1A shows the coil 48 being formed by winding the winding wire in this winding space. The outer rim 44 is provided on the side of the insulator 40 facing the outer core 36. Circumferential end faces of the coil winding surface 46, which are radially inner surfaces of the rims 44, have arc shapes extending along the outer core 36. The side of the coil winding surface 46 facing the tooth 34 extends along the imaginary straight line 100. The coil 48 is formed by a concentrated and normal winding of the winding wire on the insulator 40 of each coil core 32.
[0023] As it is in Fig. As shown in Figure 2, a dielectric resin material 50 covers the stator core 30, the insulators 40, and the coils 48, except for a radial inner surface and a radial outer surface of the stator core 30. An end cover 52 is integrally resin-molded with the dielectric resin material 50 to form the ejection terminal 206. The terminals 56, which are exposed and thus embedded (insert-molded) in the end cover 52, are electrically connected to the coils 48.
[0024] The rotor 60 has a shaft 62 and a permanent magnet 64 and is positioned within the stator core 30 such that the rotor 60 is rotatable. Both end sections of the shaft 62 are rotatably supported by bearings 26. The permanent magnet 64 is a plastic magnet produced by incorporating magnetic powders into a thermoplastic resin such as polyphenylene sulfide (PPS) and polyacetal (POM) to form a cylindrical shape. The permanent magnet 64 has eight magnetic sections 65 oriented in the direction of rotation. The eight magnetic sections 65 are polarized such that opposite magnetic poles are alternately formed in the direction of rotation on their outer surface faces that face the coil core 32.
[0025] The following describes a winding process for winding the winding wire that forms the coil 48. (1) First, the coil core 32 is formed by caulking magnetic steel sheets stacked lengthwise. 2) The insulators 40 are fitted to the corresponding coil core 32 from both end sides in the longitudinal direction of the coil core 32 for assembly. (3) The coil core 32, which is assembled with the insulators 40, is mounted on a base 122 of a winding device 120 according to Fig. 3 is mounted in a condition (a state) in which the outer rim core 36 points downwards. A mounting surface 124 of the base 122, on which the coil core 32 is mounted, has a recessed curved surface corresponding to a projecting curved surface of the outer rim surface of the outer rim core 36. Guides 130 are attached to both end faces transversely to the base 122, and guides 134 are attached to both end faces longitudinally to the base 122. A guide surface 132 at an upper end of the guide 130 extends straight ahead longitudinally to the coil core 32 and is shaped to have a smooth, projecting curved surface facing a winding wire 142 in order to guide the winding wire 142. Furthermore, a guide surface 136 on an upper end of the guide 134 has a shape that generally extends along the coil winding surface 46 of the insulator 40.This means that the circumferential sides of the guide surface 136 extend along the arc of the circumferential sides of the coil winding surface 46 of the insulator 40, with a center of the guide surface 136 also generally extending on the side of the coil winding surface 46 of the insulator 40 facing the tooth 34. Furthermore, the guide surface 136 is shaped such that it has a smooth, projecting curved surface facing the winding wire 142 in order to guide the winding wire 142. (4) After mounting or attaching the coil core 32, which is assembled with the insulators 40, onto the base 122, a nozzle 140, which feeds the winding wire 142, is brought close to the coil core 32. (5) Then, as it is stated in Fig. Figure 3A shows that, under a condition in which the winding wire 142 is held under tension in contact with the guide surface 132 on the upper end of the guide 130, the nozzle 140 moves in the longitudinal direction of the coil core 132. When the nozzle 140 reaches an end face of the coil core 32 in the longitudinal direction, the winding wire 142 is moved from the guide surface 132 of the guide 130 to the guide surface 136 of the guide 134. (6) The nozzle 140 is moved from a circumferential end of the guide surface 136 to the tooth 34 under a condition in which the winding wire 142 is held under a downward tension. The nozzle 140 is then temporarily stopped or moved slowly around the tooth 34. In this way, the winding wire 142 can be pushed to the side of the coil winding surface 46 of the insulator 40 facing the tooth 34. The side of the coil winding surface 46 of the insulator 40 facing the tooth 34 is arranged radially outside the ends in the circumferential direction of the side of the coil winding surface 46 facing the outer edge core 36 with respect to the imaginary straight line 100.
[0026] Furthermore, if the winding wire is wound in the winding space of the insulator 40, which is arranged radially inside the ends in the circumferential direction of the side of the coil winding surface 46 facing the outer edge core 36 with respect to the imaginary straight line 100, the winding wire is wound through the normal winding in a condition in which the winding wire 142 is not pressed against the guide surface 136. In this way, the winding wire 142 is wound on the insulator 40, which is attached to each coil core 32, through the concentrated winding and the normal winding.
[0027] According to the first unclaimed example described above, the outer edge core 36 of the coil core 32 has a uniform thickness, and the side of the inner edge surface 37 facing the tooth 34 is positioned radially outside the imaginary straight line 100 that connects the ends in the circumferential direction of the inner edge surface 37 of the outer edge core 36. As a result, the coil core 32 is not connected at a section unnecessary for the magnetic circuit (for example, a side of the outer edge core 304 of the coil core 300 facing the tooth 302, as described in the prior art). Fig. 9) shaped, but a part of the insulator 40 is provided instead. In this way, the size of the coil core 32 is reduced, and at the same time the winding space defined by the insulator 40 is increased. That is to say, according to the present unclaimed example, the side of the inner edge surface of the outer edge core facing the tooth is positioned on a radially outer side of the imaginary straight line that connects both ends in the circumferential direction of the inner edge surface of the outer edge core, which is why this is thinner.
[0028] Therefore, if the number of turns of the winding wire 142 is identical, the positions of the ends can be moved in the direction of rotation of the wound coil 48 and can be brought closer to the tooth 34. Typically, the circumferential end faces of the wound coil 48 are recessed towards the tooth 34. As a result, as shown in Fig. As shown in Figure 1B, a free space 110 defined between the surrounding adjacent coils 48 becomes larger, so that dielectric behavior is achieved between the coils 48.
[0029] Furthermore, since the side of the coil winding surface of the insulator facing the tooth is positioned radially outside the imaginary straight line, the winding space is increased. Thus, by making the unnecessary section for the magnetic circuit thinner, the winding space can be increased without impairing magnetic performance. In particular, because the winding space of insulator 40 is larger, the need to place coils arranged around the perimeter excessively close to each other is restricted, while still allowing for an increase in the number of turns. This improves motor efficiency.
[0030] Since the side of the coil winding surface 46 of the outer rim of the insulator 40 facing the tooth is also the flat surface extending along the imaginary straight line 100, the winding wire can easily be wound along the coil winding surface 46 in a condition where a fault winding is confined at the back of the insulator 40. According to an unclaimed example, the coil collapses when the fault winding occurs. Second and third unclaimed example
[0031] Below is a second unclaimed example in Fig. 4 illustrates this, and a third unclaimed example is in Fig. Figure 5 illustrates this. Essentially identical components, identical to those in the first unclaimed example, are designated by the same reference numerals.
[0032] According to the in Fig. In the second unclaimed example illustrated in Figure 4, outer rings 72, arranged on a side of an insulator 70 facing the outer edge core 36, have curved shapes extending along the outer edge core 36 from both ends in the circumferential direction towards the tooth 34. Furthermore, a side of a coil winding surface 74 facing the tooth 34, which is a radially inner surface of each outer ring 72, is positioned radially outside the imaginary straight line 100. In addition, the sides of the coil winding surfaces 74 of the outer rings 72 facing the tooth 34 are not flat surfaces, unlike in the first unclaimed example. The coil winding surfaces 74 have recessed curved shapes extending from the corresponding ends in the circumferential direction towards the tooth 34.
[0033] In the insulator 70 shaped as described above, the guide surface 136 corresponds to the guide 134 of the winding device 120 according to Fig. 3 according to the first unclaimed example of a shape of the coil winding surface 74 of the outer ring 72 of the insulator 70 according to the second embodiment. Therefore, the winding wire 142 can be wound in the winding space of the insulator, which is defined radially outside the imaginary straight line 100, by concentrated winding and normal winding.
[0034] According to the in Fig. In the third unclaimed example illustrated in Figure 5, the shapes of the coil core 32 and the insulators 40 are identical to those of the first unclaimed example. However, the winding wire 142, which forms a coil 80, is wound by random winding instead of normal winding.
[0035] According to the unclaimed example described above, the motor according to the present invention is used in the fuel pump. However, the motor according to the present invention is not limited to the fuel pump, but can be used as a drive source for another device. Example of implementation
[0036] An embodiment of the present invention is described below with reference to the drawings. Similar components of a motor according to the present embodiment, which are similar to the components of the motor according to the first unclaimed example, are designated by the same reference numerals.
[0037] A fuel pump that uses an engine according to the embodiment of the present invention is in Fig. Figure 7 shows a fuel pump 10a according to the present embodiment, for example a turbine pump of the tank-mounted type, which is provided in a fuel tank of a two-wheeled vehicle with a displacement of 150 cm3 or less.
[0038] The fuel pump 10a comprises a pump 12 and a motor 14a, which rotatably drives the pump 12. The housing of the fuel pump 10a is constructed from housings 16 and 18. Each housing 16 and 18 is formed into a cylindrical shape by pressing sheet metal, and housing 18 is press-fitted into and attached to housing 16. Housing 16 also serves as a housing for the pump 17 and the motor 14a and is designed to have a thickness of approximately 0.5 mm. Both longitudinal end sections of housing 16 rivet a pump housing 20 and a stator core 30a to secure them. A pump box (pump housing) 22 and the stator core 30a are pressed against the longitudinal ends of housing 18 such that their longitudinal positions are determined.
[0039] Pump 12 is a turbine pump comprising pump housings 20 and 22 and an impeller 24. Pump housing 22 is press-fitted into the casing 16 and pressed longitudinally against the casing 18. Pump housings 20 and 22 are designed to accommodate the impeller 24 as a rotatable component. A C-shaped pump channel 202 is provided at each gap between the impeller 24 and each of the pump housings 20 and 22. The pressure of fuel, introduced through an inlet port 200 on pump housing 20, is increased in the pump channel 202 by the rotation of the impeller 24, whereupon the fuel is pumped to the engine 14a. The fuel pumped to the motor 14a flows through a fuel channel 204, which is located between the stator core 30a and a rotor 60, and is then supplied to the internal combustion engine via an exhaust port 206.
[0040] Motor 14a is a so-called brushless motor of the internal rotor type. Motor 14a has a stator core 30a, insulators 40a, and coils 48. As shown in Fig. 6A and Fig. As shown in Figure 6B, the stator core 30a is constructed from six coil cores 32a, each separate and arranged circumferentially at regular intervals. The coil core 32a is formed by mutually sealing magnetic steel sheets stacked longitudinally.
[0041] The coil core 32a has a radially extending tooth 34a and an outer edge core 36a extending in both circumferential directions from a radially outer side of the tooth 34a. An outer edge surface of the outer edge core 36a has a curved shape, and the outer edge cores 36a of the six coil cores 32a form an outer edge section of the stator core 30a, which has an annular shape with almost no gap between them. With respect to an imaginary straight line 100 connecting both ends in the circumferential direction of an inner edge surface 37a of the outer edge core 36a, both circumferential sides of the inner edge surface 37a are inclined more radially inward as the ends approach circumferentially adjacent coil cores 32.For example, each circumferential end of the inner edge surface 37a is inclined more radially inwards in a position of the inner edge surface 37a if the position is closer to a corresponding circumferentially adjacent coil.
[0042] The side of the inner edge surface 37a of the outer edge core 36a facing tooth 34a is a flat surface along the imaginary straight line 100. This means that the side of the inner edge surface 37a of the outer edge core 36a facing tooth 34a is positioned radially outside the imaginary straight line 100 and is recessed. The side of the outer edge core 36a facing tooth 34a is thicker than the surrounding sides of the outer edge core 36a, and this thicker section is unnecessary for a magnetic circuit. Therefore, even if the side of the inner edge surface 37a of the outer edge core 36a facing tooth 34a is positioned radially outside the imaginary straight line 100 and is recessed, the magnetic behavior is not impaired.If α is defined as an angle of inclination with which the ends are inclined more radially inwards in the circumferential direction of the inner edge surface 37a of the outer edge core 36a as the ends approach circumferentially adjacent coil cores 32a in the circumferential direction relative to the imaginary straight line 100, then α is designed to have a relationship of 25° ≤ α ≤ 35° according to the present embodiment.
[0043] A pair of insulators 40a is shaped such that they have essentially the same form. The pair of insulators 40a is fitted with a corresponding coil core 32a at both longitudinal ends and attached to the coil core 32a. Each insulator 40a has inner rings 42a on a radially inner side and outer rings 44a on a radially outer side to form winding spaces defined between the inner ring 42a and the outer ring 44a, as shown in Fig. Figure 6A shows that the coil 48 is formed by winding the winding wire in these winding spaces. The outer rim 44a is provided on a flat surface section, which is the inner edge surface 37a of the outer edge core 36a, and is recessed radially outwards with respect to the imaginary straight line 100.
[0044] A coil winding surface 46a is a radially inner surface of each outer ring 44a and is a flat surface extending along the imaginary straight line 100, which is positioned at the coil winding surface 46a. This means that the position of the opening of the outer ring core 36a generally corresponds to the position of an opening of the outer ring 44a of the insulator 40a (an outer ring core side of the opening position of the coil core generally corresponds to an outer ring core side of an opening position of the insulator). Therefore, the winding wire can easily be wound along the coil winding surface 46a of the outer ring 44a from the opening on the side of the coil core 32a facing the outer ring core 36a. The coil 48 is formed by concentrated winding and normal winding of the winding wire on the insulator 40a of each coil core 32.
[0045] As it is in Fig. As shown in Figure 7, dielectric resin material 50 covers the stator core 30a, the insulators 40a, and the coils 48, except for a radial inner surface and a radial outer surface of the stator core 30a. An end cover 52 is integrally molded with the dielectric resin material 50 to form the ejection terminal 206. The terminals 56, which protrude from the end cover 52 and are thus encapsulated by insert molding, are electrically connected to the coils 48.
[0046] The rotor 60 has a shaft 62 and a permanent magnet 64 and is positioned within the stator core 30a such that the rotor 60 is rotatable. Both end sections of the shaft 62 are rotatably supported by bearings 26. The permanent magnet 64 is a plastic magnet produced by encasing magnetic powders in thermoplastic resin such as polyphenylene sulfide (PPS) and polyacetal (POM) to form a cylindrical shape. The permanent magnet 64 has eight magnetic sections 65 oriented in the direction of rotation. The eight magnetic sections 65 are polarized such that opposite magnetic poles are formed alternately in the direction of rotation on their outer surface faces, which are oriented towards the coil cores 32a.
[0047] With respect to the rotor 60, which has the polarized permanent magnet 64 described above, a control device (not shown) switches the supply to the coil 48, which is wound around each coil core 32a, in order to switch magnetic poles, which are generated on inner edge surface sides of the coil cores 32a forming the stator core 30a, in the sequence of a rotating direction such that the rotor 60 rotates.
[0048] The following describes a winding process for winding the winding wire that forms the coil 48. (1) First, the coil core 32a is formed by crimping together magnetic steel sheets stacked in a longitudinal direction. (2) The insulators 40a are fitted with the corresponding coil core 32a from both ends in the longitudinal direction of the coil core 32a for assembly. In this state, the position of the opening of the outer rim core 36a generally coincides with the position of the opening of the outer ring 44a of the insulator 40a. (3) The coil core 32a, which is assembled with the insulators 40a, is mounted on a base 122 of a winding device 120a according to Fig. 8A, Fig. 8B is mounted in a condition where the outer rim core 36a points downwards. A mounting surface 124 of the base 122, on which the coil core 32a is mounted, has a recessed curved surface corresponding to a projecting curved surface of the outer rim surface of the outer rim core 36a. Guides 130 are attached to both end faces transversely to the base 122, and guides 134 are attached to both end faces longitudinally to the base 122. A guide surface 132a at an upper end of the guide 130a extends straight longitudinally to the coil core 32a and is shaped to have a smooth, projecting curved surface facing a winding wire 142 to guide the winding wire 142. Furthermore, a guide surface 136a at an upper end of the guide 134a has a straight shape generally along the coil winding surface 46a of the outer ring 44a of the insulator 40a.Furthermore, the guide surface 136a is shaped such that it has a smooth, projecting curved surface towards the winding wire 142 in order to guide the winding wire 142. (4) After mounting the coil core 32a, which is assembled with the insulators 40a, on the base 122, a nozzle 140, which feeds the winding wire 142, is brought close to the coil core 32a. (5) Then, as it is stated in Fig. As shown in Figure 3A, under a condition in which the winding wire 142 is held under tension in contact with the guide surface 132a at the upper end of the guide 130a, the nozzle 140 moves longitudinally along the coil core 32a. When the nozzle 140 reaches a longitudinal end face of the coil core 32a, the winding wire 142 moves from the guide surface 132a of the guide 130a to the guide surface 136a of the guide 134a. Then, under a condition in which the winding wire 142 is held under tension in contact with the guide surface 136a at the upper end of the guide 134a, the winding wire 142 is wound.
[0049] In this way, the winding wire 142 is wound on the insulator 40a, which is attached to each coil core 32a, by concentrated winding and normal (regular) winding.
[0050] According to the embodiment described above, the ends of the inner edge surface 37a are inclined radially inwards with respect to the imaginary straight line 100 as they approach adjacent coil cores 32a. This means that the side of the inner edge surface 37a of the outer core 36a facing the tooth 34a is recessed radially outside the imaginary straight line 100. Therefore, the coil winding surface 46a of the insulator 40a, which covers the coil core 32a, can be positioned radially further outwards on the side facing the outer core 36a. As a result, the size of the motor 14a of the fuel pump 10a can be reduced, and the winding space formed by the insulator 40a can be increased.Thus, for the same number of turns, both end positions in the direction of rotation of the coil 48, which is wound on each coil core 32a, can be offset towards the tooth 34a. Therefore, since a free space 110 between the adjacent coils in the direction of rotation can be larger, as shown in . Fig. 6A and Fig. As shown in Figure 6B, an insulation fault between adjacent coils in the direction of rotation is limited. Furthermore, the winding space is increased, preventing the coils from being excessively close together, and the number of turns can still be increased. Thus, the motor efficiency can be improved. Since the motor described above is used, the size of a fuel pump using the motor can be reduced.
[0051] According to the embodiment described above, the inclination angle α, which is the inclination of both circumferential sides of the inner edge surface 37a of the outer edge core 36a with respect to the imaginary straight line 100, is designed to be 25° ≤ α ≤ 35° under a condition in which the six coil cores 32a form the stator core 30a. The inclination angle α decreases when the number of coil cores forming the stator core increases and when the circumferential length of the outer edge core is shortened. Furthermore, the inclination angle α increases when the number of coil cores decreases and the circumferential length of the outer edge core is lengthened. For example, in a case where the number of coil cores is four, α is set as 40° ≤ α ≤ 50°, and in a case where the number of coil cores is four, α is set as 17.5° ≤ α ≤ 27.5°.
[0052] The angle of inclination α is not limited to the area described above, but the angle of inclination can assume any size, as long as the ends are inclined more inwards in the direction of rotation of an inner edge surface of the outer edge core with respect to the imaginary straight line connecting the ends in the direction of rotation of the inner edge surface of the outer edge core, as the ends approach adjacent coil cores in the direction of rotation.
[0053] Furthermore, to reduce the size of the motor while still increasing the winding space of the coil, the circumferential sides of the inner surface of the outer core are not necessarily inclined more radially inwards with respect to the imaginary straight line connecting the ends in the circumferential direction of the inner surface of the outer core as the ends approach adjacent coil cores in the circumferential direction. However, a side of the inner surface of the outer core facing the tooth can be recessed radially outwards with respect to the imaginary straight line connecting the ends in the circumferential direction of the inner surface of the outer core.
[0054] Furthermore, according to the embodiment described above, the motor according to the present invention was used in the fuel pump. However, the motor according to the present invention is not limited to the fuel pump, but can be used as a drive source for another device.
[0055] According to the embodiment described above, the winding wire is wound normally to form the coil 48. However, the winding wire can be wound randomly to form a coil.
[0056] Thus, the present invention is not limited to the embodiments described above, but can be applied to various embodiments, as long as the scope is not exceeded.
[0057] Additional advantages and modifications are understandable to those skilled in the art. The invention, in its broader sense, is therefore not limited to the specific details, representative device, and illustrated examples shown and described above.
Claims
Motor with a stator core (30a) having a plurality of coil cores (32a) arranged circumferentially, each of the plurality of coil cores (32a) having a tooth (34a) extending radially and an outer edge core (36a) extending circumferentially on a radially outer side of the tooth (34a), and ends in the circumferential direction of an inner edge surface (37a) of the outer edge core (36a) with respect to an imaginary straight line (100) connecting the ends in the circumferential direction of the inner edge surface (37a) of the outer edge core (36a), with the ends approaching circumferentially adjacent coil cores (32a) being inclined more radially inwards, insulators (40a) each covering a corresponding plurality of the coil cores (32a), wherein a side of a coil winding surface facing the outer edge core (36a) (46a) each insulator (40a) extends along the imaginary straight line (100), coils (48),which are each wound on a corresponding insulator (40a), and a rotor (60) which is rotatably provided with respect to an inner circumferential side of the stator core (30a), wherein different magnetic poles are alternately arranged in the direction of rotation on an outer edge surface of the rotor (50), and the outer edge surface of the rotor (60) faces the stator core (30a), wherein the imaginary straight line (100) is positioned on a side of the coil winding surface (46a) facing the outer edge core (36a), α is defined as an inclination angle with which the ends approach, in the direction of rotation of the inner edge surface (37a) of the outer edge core (36a) with respect to the imaginary straight line (100) connecting the ends in the direction of rotation of the inner edge surfaces (37a) of the outer edge core (36a), with the ends approaching, in the direction of rotation, adjacent coil cores arranged circumferentially. (32a) are inclined radially inwards, wherein, if the coil cores (36a) are four coil cores (36a),40° ≤ α ≤ 50° applies if there are six coil cores (36a), 25° ≤ α ≤ 35° applies, and if there are eight coil cores (36a), 17.5° ≤ α ≤ 27.5° applies. Motor according to claim 1, wherein the side of the coil winding surface (46a) of each insulator (40a) facing the outer edge core (36a), which extends along the imaginary straight line (100), is a flat surface. Fuel pump comprising a motor (14a) according to claim 1 or 2, and a pump (12) driven by the motor (14a), wherein the pump (12) receives fuel and increases the pressure of the fuel.