Stator for a rotary DC brushless motor

Abstract: A brushless DC motor and its stator. The stator comprises a magnetic conductive tube (30) with a pole plate (111) at one end. The edge of the pole plate functions as magnetic pole (112). The other end of the magnetic conductive tube is combined with another pole plate (21). A coil (301) is wounded between the two pole plates. The edge of both pole plates further extended toward opposite direction to form larger magnet pole area.

Description: Background of the Invention 1. Field of the Invention The present invention relates to a brushless DC motor to the structure of the stator a brushless DC motor, the stator including a magnetic conductive tube and a pole plate. 2. Description of the Related Art Referring to FIG1, a conventional brushless DC motor and stator comprises a metal tube 91 with outer surface surrounded by a coil 92, an upper pole plate 93, a lower pole plate 94 and a circuit board 95. The upper plate 93 and the lower plate 94 are formed by a plurality of stacked silicon steel plates so as to increase the area adjacent to the permanent magnet of the rotor. Because it consists of a plurality of silicon steel plates, the conventional motor and stator are complex and the cost of manufacture is high, and much more of the material. Furthermore, one end of the metal tube 91 has an annular flange 911 which is larger than the diameter of the tube. When the other end of metal tube91 being fixed, the annular flange 911 limits the coil 92, the upper plate 93, the lower plate 94 and the circuit board 95, and thus the thickness of annular flange 911 increases the thickness of the stator. In order to decrease the thickness of the stator, the annular flange 911 may be removed for the best design. Furthermore, U.S. Patent 4,891,567, issued on Jan. 2, 1990 to Fujitani et al., discloses a pole plate having a pole which is bent in a right angle to the pole plate. The poles are bent toward each other, so that the poles cover the outer peripheral space of the coil seat. Thus, the pole plates are pressed and combined on the stator, after coils have been wounded on the coil seat of the stator. However, the poles of the stator are arranged to face each other because coils must first be wounded on the coil seat of the stator, and then the pole plates are pressed on the bobbin to form the stator. The pressing process of pole plates into a bobbin with a coil wound has the disadvantage that the coil wire may be cut or broken ,the bobbin being pressed, and the enameled layer of wires damaged. Wires of the coil suffer from starting current pulses in the long term resulting in the degrading of the coil assembly and resulting in deterioration of rotation of the motor and shortening motor life. US 5,808,390 discloses a plurality of pole plates extending in relative direction to another pole plate from either of the opposite sides of the stator. It is obvious that the pole of the pole plate shown in this document obstructs the wire-winding process and is capable of cutting the winding wire extending therebetween. Summary of the Invention The primary object of this invention is to provide a stator of a brushless DC motor according to claim 1. The secondary object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube, which has a pole plate on one end of the tube, and another pole plate sleeved on the other end of the tube. At least one of the two pole plates has poles which extend in opposite directions to the poles of the other pole plate to form a larger conductive area of the pole plate so as to increase the torque of motor, and to permit freedom of design in accordance with the requirements of the motor without the limitation of space. The third object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube, which has a pole plate on one end of the tube, and another pole plate sleeved on the other end of the tube. At least one of the two pole plates has poles which extend in an opposite direction to those of the other pole plate to form a larger conductive area of the pole plate so as to reduce the thickness of pole plate, manufacture processes and the material cost of the pole plate. The fourth object of this invention is to provide a stator of a brushless DC motor comprising a magnetic conductive tube whose outer surface may wind a coil or support a bobbin for a coil to simplify production processes and reduce the cost of manufacture. The fifth object of this invention is to provide a stator of a brushless DC motor which has a thinner thickness that uses lesser material and reduces the processes of manufacture, in order to reduce the material and the manufacturing cost. In accordance with the present invention, a brushless DC motor comprises a magnetic conductive tube, which has a pole plate on one end of the tube and wound coils on the outer surface of the tube, and another pole plate is sleeved on the other end of the tube. The edge of both pole plates have poles extending in opposite directions to form a larger pole edge area to increase magnetic inductive area. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. Brief Description of the Drawings The present invention will now be described in detail with reference to the accompanying drawings wherein; Fig. 1 is a perspective exploded view of a conventional brushless DC motor; Fig. 2 is an exploded perspective view of a stator which is not part of the present invention; Fig. 3 is a top view of the stator of fig 1; Fig. 4 is a sectional view, along line 4-4, of the brushless DC motor of fig 3; Fig. 5 is an exploded perspective view of a brushless DC motor in accordance with the first embodiment of the present invention; Fig. 6 is a sectional view of the brushless DC motor in accordance with the first embodiment of the present invention; Fig. 7 is an exploded perspective view of a brushless DC motor in accordance with a second embodiment of the present invention; Fig. 8 is an exploded perspective view of a brushless DC motor in accordance with a second embodiment of the present invention; Fig. 9 is an exploded perspective view of a brushless DC motor in accordance with a second embodiment of the present invention; Fig. 10 is an exploded perspective view of a brushless DC motor in accordance with a third embodiment of the present invention; Fig. 11 is a sectional view of the brushless DC motor in accordance with the third embodiment of the present invention; Fig. 12 is an exploded perspective view of a brushless DC motor; Fig. 13 is a sectional view of the brushless DC motor in accordance with fig 12; Fig. 14 is a sectional view of the brushless DC motor in accordance with fig 12; Fig. 15 is an exploded perspective view of a brushless DC motor in accordance with the fourth embodiment of the present invention; Fig. 16 is a sectional view of the brushless DC motor in accordance with the fourth embodiment of the present invention; Fig. 17 is an exploded perspective view of a brushless DC motor in accordance with the fifth embodiment of the present invention; Fig. 18 is a sectional view of the brushless DC motor in accordance with the fifth embodiment of the present invention; Fig. 19 is an exploded perspective view of a brushless DC motor in accordance with the sixth embodiment of the present invention; Fig. 20 is a sectional view of the brushless DC motor in accordance with the sixth embodiment of the present invention; Fig. 21 is an exploded perspective view of a brushless DC motor in accordance with the seventh embodiment of the present invention; Fig. 22 is a sectional view of the brushless DC motor in accordance with the seventh embodiment of the present invention; Fig. 23 is an exploded perspective view of a brushless DC motor in accordance with the eighth embodiment of the present invention; Fig. 24 is a sectional view of the brushless DC motor in accordance with the eighth embodiment of the present invention; Fig. 25 is an exploded perspective view of the brushless DC motor in accordance with the first embodiment of the present invention; Fig. 26 is a sectional view of the brushless DC motor in accordance with the first embodiment of the present invention; Fig. 27 is an exploded perspective view of the brushless DC motor in accordance with the first embodiment of the present invention with fixing member; Fig. 28 is an exploded perspective view of the brushless DC motor in accordance with the first embodiment of the present invention with case Fig. 29 is an exploded perspective view of the brushless DC motor in accordance with the first embodiment of the present invention with cooler device. Detailed Description of the Invention Referring to Fig. 2, a brushless DC motor comprises a magnetic conductive tube 10, a pole plate 20 and a bobbin 30. The magnetic conductive tube 10 is made of magnetizable material, forming a pole plate 101 on one end of the tube 10, so that the tube 10 and the pole plate 101 together form a body. The plate 101 forms poles 102. An inner periphery of the magnetic conductive tube 10 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer periphery is provided to sleeve the pole plate 20 and the bobbin 30 thereon. The pole plate 20 sleeved on the outer periphery of the magnetic conductive tube 10 has poles 201 which interact with a permanent magnet of a rotor (not shown) so as to rotate the motor smoothly, and the number of the poles 201 are provided in accordance with the design requirement of motor's pole number. The bobbin 30 is essentially made of insulation material such as plastic, and sleeved on the outer periphery of the magnetic conductive tube 10. The bobbin 30 sleeves tightly or loosely with the outer periphery of the magnetic conductive tube 10 according to design requirements. The bobbin 30 is positioned between the pole plate 101 and the pole plate 20 and coil 301 is wound on the bobbin 30, as shown in Fig. 4. It is easy and convenient to wind the coil 301 on the bobbin 30, before or after the magnetic conductive tube 10 and the bobbin 30 are assembled. Either way may achieve the goal of easy assembly. Referring to Figs.3 and 4, which show a stator. The bobbin 30 is held between the pole plate 101 and the pole plate 20, and coil 301 is wound on the outer peripheral of bobbin 30. Insulation layer is needed between coil 301, pole plate 101 and the pole plate 20, to thus form a stator. Referring to Fig. 5, a brushless DC motor in accordance with the first embodiment of the present invention comprises a magnetic conductive tube 11, a pole plate 21 and a bobbin 30. The magnetic conductive tube 11 is made of magnetizable material forming a pole plate 111 on one end, the pole plate 111 having poles 112, the outer edge of the poles 112 extending to the opposite direction of the other pole plate 21 so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 111 has a larger induction area. The number of poles 112 are provided in accordance with the design requirement of the motor's pole number. An inner periphery of the magnetic conductive tube 11 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer periphery is provided to sleeve the pole plate 21 and the bobbin 30 thereon. The pole plate 21 is sleeved on the outer periphery of the magnetic conductive tube 11, the pole plate 21 having poles 211, and the outer edge of the poles 211 extending in an opposite direction to those of the pole plate 11 so as to increase the induction area of stator to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate 111 has a larger induction area. The number of poles 112 are provided in accordance with the design requirement of the motor's pole number. The bobbin 30 is the same as in figure 1, and sleeved the outer peripheral of the magnetic conductive tube 10. The bobbin 30 sleeves tightly or loosely around the outer periphery of the magnetic conductive tube 10, the bobbin 30 is positioned between the pole plate 111 and the pole plate 21 therebetween. It is easy and convenient to wind coils on the bobbin 30 before or after the magnetic conductive tube 10 and the bobbin 30 are assembled. Either way may achieve the goal of easy manufacturing. Fig. 6 shows the situation of the combination of the first embodiment of the present invention. The bobbin 30 is held between the pole plate 111 and the pole plate 21, and coil 301 is wound on the outer peripheral of bobbin 30. An insulated layer is provided between the coil 301, the pole plate 111 and the pole plate 21, and thus it forms a stator. Referring to Fig. 7, a brushless DC motor in accordance with the second embodiment of the present invention comprises a magnetic conductive tube 11, a pole plate 22 and a bobbin 30 corresponding to the second embodiment. The third embodiment further comprises an inclined portion 113, 222 respectively formed on the poles 112, 221 which, unlike the second embodiment, forms an irregular magnetic field. Because of the irregular magnetic field, the stator drives the rotor easily at the beginning of the motor start-up. Referring to Fig. 8, the second embodiment of the present invention further comprises a magnetic conductive tube 11, a pole plate 22 and a bobbin 30. The second embodiment further comprises a lower portion 114, 223 instead of the inclined portion 113, 222 respectively formed on the poles 112, 221 to form an irregular magnetic field. And, the third embodiment further comprises a recessed portion 115, 224 respectively formed on the poles 112, 221 to form an irregular magnetic field, as shown in Fig. 9. Because of the irregular magnetic field, the stator drives the rotor easily at the beginning of the motor start-up. Referring to Fig. 10, a brushless DC motor in accordance with the third embodiment of the present invention comprises two pole plates 21, a bobbin 30 and a magnetic conductive tube 40. The magnetic conductive tube 40 is made of magnetizable material, forming an annular flange 401 on one end so as to hold the pole plate 21 in place. An inner periphery of the magnetic conductive tube 40 is provided with a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface to sleeve the two pole plates 21 and the bobbin 30 thereon. The number of pole plates 21 is more than two, the plate being sleeved on the outer surface of the magnetic conductive tube 40 to be held in place by the annular flange 401. The pole plate 21 has poles 211, the outer edge of the poles 211 extending into the opposite direction to those of the pole plate 11 so as to increase the induction area of the stator relative to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate 111 has a larger induction area. The number of poles 112 are provided in accordance with the design requirement of the motor's pole number. The bobbin 30 is essentially made of insulation material such as plastic, and was sleeved to the outer peripheral of the magnetic conductive tube 10. The bobbin 30 sleeves tightly or loosely on the outer surface of the magnetic conductive tube 10. The bobbin 30 is positioned between the pole plate 101 and the pole plate 20 therebetween and wire are coiled on the bobbin 30 thereon to form a coil 301. It is easy and convenient to wind the coil 301 on the bobbin 30 before or after the magnetic conductive tube 10 and the bobbin 30 are assembled. Either way may achieve the goal of easy assembly. Fig. 11 shows the situation of the combination of the third embodiment of the present invention. The bobbin 30 is held between the two pole plates 21, and the coil 301 wound on the outer surface of bobbin 30. An insulated layer is provided between the coil 301 and the two pole plates 21, to thus form a stator. Referring to Fig. 12, a brushless DC motor comprises a bobbin 30 and two magnetic conductive tubes 50. The magnetic conductive tube 50 is made of magnetizable material forming a pole plate 501 on one end, the pole plate 501 having poles 502, the outer edge of the poles 502 extending in an opposite direction relative to those of the other pole plate 501 so as to increase the induction area of the stator relative to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 501 has a larger induction area. The number of poles 502 are provided in accordance with the design requirement of the motor's pole number. The magnetic conductive tubes 50 are attached to each other and form an inner peripheral which is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate 21 and the bobbin 30 thereon. The bobbin 30 is essentially made of insulation material such as plastic, and was sleeved to the outer surface of the magnetic conductive tube 50. The bobbin 30 is sleeved tightly or loosely on the outer surface of the two attached magnetic conductive tube 50. The bobbin 30 is positioned between the two pole plates 501 therebetween. Coil 301 is wound on the bobbin 30. It is easy and convenient to wind the coil 301 on the bobbin 30 before or after the magnetic conductive tube 50 and the bobbin 30 are assembled. Either way may achieve the goal of easy assembly. Fig. 13 shows the situation of a stator. The bobbin 30 is sleeved to the outer surface of the two attached magnetic conductive tube 50, and coil 301 is wound on the outer surface of bobbin 30. An insulated layer is provided between the coil 301 and the pole plates 501), thus forming a stator to be fixed onto a supporter 53. Referring to Fig. 14, a stator comprises two magnetic conductive tubes 51 and 52 having different diameter. The magnetic conductive tube 51 has a smaller diameter than the magnetic conductive tube 52 such that the outer surface of the magnetic conductive tube 51 is held in the inner surface of the magnetic conductive tube 52. The bobbin 30 is sleeved to the outer surface of the magnetic conductive tube with the large diameter. The coil 301 is wound on the outer surface of bobbin 30 and an insulated layer is provided between the coil 301 and the pole plates 511, thus forming a stator to be fixed on to a supporter 53 by the magnetic conductive tube with the smaller diameter. Referring to Fig. 15, a brushless DC motor in accordance with the fourth embodiment of the present invention comprises a magnetic conductive tube 11, a pole plate 20 and a bobbin 31. The magnetic conductive tube 11 is made of magnetizable material forming a pole plate 111 on one end, the pole plate 111 having poles 112, the outer edge of the poles 112 extending in an opposite direction than those of the other pole plate 21 so as to increase the induction area of the stator relative to the permanent magnet of a rotor, so that the thickness of a single plate of the pole plate 111 has a larger inductive area. The number of poles 112 are provided in accordance with the design requirement of the motor's pole number. An inner periphery of the magnetic conductive tube 11 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate 21 and the bobbin 30 thereon. More than one pole plate 20 are sleeved to the outer surface of the magnetic conductive tube 10. It has poles 201 to interact with a permanent magnet of a rotor (not shown) so as to rotate the motor smoothly, and the number of poles 201 are provided in accordance with the design requirement of the motor's pole number. The bobbin 31 is essentially made of insulation material such as plastic, and sleeved to the outer surface of the magnetic conductive tube 11. The bobbin 31 sleeves tightly or loosely to the outer surface of the magnetic conductive tube 11, and is positioned between the pole plate 111 and the pole plate 20 and coil 311 being wound on the bobbin 31. It is easy and convenient to wind the coil 311 on the bobbin 31 before or after the magnetic conductive tube 11 and the bobbin 31 are assembled. Either way may achieve the goal of easy assembly. The fourth embodiment further discloses a positioning structure, comprises a plurality of holes 116, 202 respectively defined by the pole plates 111, 20 thereon. On two ends of the bobbin 31 are two discs 312 which limit the coil therebetween and insulate the coil from the plates 111, 20. And the two plates 312 have a plurality of posts 313 extending outward therefrom. The posts 313 fit into the holes 116, 202 so as to position easily and accurately the magnetic conductive tube 11 and the plate 111,20 on the bobbin 31. Because two discs 312 insulate the coil from the plates 111, 20, there is no need to provide an insulated layer which insulates the coil 301 from the plates 111, 20. Fig. 16 shows the situation of the combination of the fourth embodiment of the present invention. The bobbin 31 is held between the pole plate 111 and the pole plate 20, and coil 311 is wound on the outer surface of bobbin 31, and thus forms a stator. Referring to Fig. 17, a brushless DC motor in accordance with the fifth embodiment of the present invention comprises a magnetic conductive tube 10, a pole plate 21 and a bobbin 30. The magnetic conductive tube 10 is made of magnetizable material, forming a pole plate 101 on one end of the tube 10 so that the tube 10 and the pole plate 101 together form a body. The plate 101 forms poles 102. An inner periphery of the tube 10 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate 20 and the bobbin 30 thereon. The number of poles 102 are provided in accordance with the design requirement of the motor's pole number. More than one pole plate 21 are sleeved on the outer surface of the magnetic conductive tube 11, the pole plate 21 having poles 211, the outer edge of the poles 211 extend in an opposite direction than the other pole plate 11 so as to increase the induction area of the stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 111 has a larger induction area. The number of poles 112 are provided in accordance with the design requirement of the motor's pole number. The bobbin 30 has been disclosed as above-mentioned, the timing of the winding the coil can be selected as required. Therefore the description is not repeated here. Fig. 18 shows the situation of the combination of the fifth embodiment of the present invention. The bobbin 30 is held between the pole plate 101 and the pole plate 21, and coil 301 is wound on the outer surface of bobbin 30 An insulating layer is provided between the coil 301, pole plate 101 and the pole plate 21, thus forming a stator. Referring to Fig. 19, a brushless DC motor in accordance with the sixth embodiment of the present invention comprises a magnetic conductive tube 12, a plate 21 and a bobbin 30. The magnetic conductive tube 12 is made of magnetizable material forming a pole plate 121 on one end, the pole plate 121 having poles 122, the outer edge of the poles 122 extend in an opposite direction than the other pole plate 21 so as to increase the induction area of the stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 121 has a larger induction area. The number of poles 122 are provided in accordance with the design requirement of motor's pole number. An inner peripheral of the magnetic conductive tube 12 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor, and an outer surface is provided to sleeve the pole plate 21 and the bobbin 30 thereon. The end of the magnetic conductive tube 12 has provided thereon an annular flange 123 with a smaller diameter than the diameter of the pole plate 121. The annular flange 123 can be processed by bending press to fix the bobbin 30 in place. The pole plate 21 and the bobbin 30 have been disclosed as above-mentioned, the timing of winding the coil can be selected as required. Fig. 20 shows the situation of the combination of the sixth embodiment of the present invention. The bobbin 30 is held between the pole plate 121 and the pole plate 21, an annular flange 123 is bent and positioned to insure that the pole plate 21 and the bobbin 30 are held in place, and coil 301 is wound on the outer surface of bobbin 30. An insulated layer is provided between the coil 301, the pole plate 121 and the pole plate 21, thus forming a stator. Referring to Fig. 21, a brushless DC motor in accordance with the seventh embodiment of the present invention comprises a pole plate 21 and a magnetic conductive tube 60. The magnetic conductive tube 60 is made of magnetizable material forming a pole plate 601 on one end, the pole plate 601 having poles 602, the outer edge of the poles 602 extend in an opposite direction than the other pole plate 21 so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 601 has a larger induction area. The number of poles 602 are provided in accordance with the design requirement of the motor's pole number. An inner periphery of the magnetic conductive tube 60 is provided to contain a bearing (not shown) therein for extending through a shaft of the rotor. The contact surface between coil 32 and outer surface of magnetic conductive tube 60 and pole plate 601 need insulation treatment and forms an insulation layer. Therefore, the outer surface of magnetic conductive tube 60 provides pole plate 21 to sleeve onto and the coil 32 may be wound onto it. The pole plate 21 is sleeved on the outer surface of the magnetic conductive tube 11, the pole plate 21 having poles 211, the outer edge of the poles 211 extending in an opposite direction than the other pole plate 602 so as to increase the induction area of stator to the permanent magnet of a rotor, so that with the thickness of a single plate, the pole plate 21 has a larger induction area. The number of poles 211 are provided in accordance with the design requirement of the motor's pole number. The contact surface between the pole plate 21 and coil 32 needs insulation treatment to form an insulated layer. Referring to Fig. 23, a brushless DC motor in accordance with the eighth embodiment of the present invention comprises a pole plate 21 and a magnetic conductive tube 61 which is the same as the ninth embodiment. The contact surface between coil 32 and the pole plate 21 and pole plate 611 needs insulation treatment to form an insulated layer. The magnetic conductive tube 61 further comprises a smaller diameter at an end 613.A ladder-shaped corner 614 is formed by the different diameter on the outer surface of the magnetic conductive tube 61 for attaching and positioning the pole plate 21 (as shown in Fig. 24). A coil 32 may be wound on the outer surface of the magnetic conductive tube 61at the section between the pole plate 611 and the pole plate 21, and thus it forms a stator. Referring to Fig. 25 and 26, a rotor 70 and a circuit board 702 are assembled to form a motor corresponding to that of the first embodiment of the present invention. The first embodiment mainly comprises the magnetic conductive tube 11, the pole plate 21, the bobbin 30, a rotor 70 and a circuit board 702. The circuit board 702 mainly sleeves to the outer surface of the magnetic conductive tube 11 so as to allow a Hall IC 703 of the circuit board 702 to respond to a permanent magnet 704 of the rotor 70. An inner periphery of the magnetic conductive tube 11 is provided to contain a bearing element therein for extending through a shaft 701 of the rotor 70 to form a brushless motor. Referring to Fig. 27, a fixing member 705 is combined with the present invention, The fixing member 705 like a substrate or a case of another product having a hole 706 through which to combine with the magnetic conductive tube 11 by means of an interference fit between different diameters, or by any other combination method. Fig. 28 shows the present invention brushless DC. motor (not labeled) and a case 82 combined together to form a cooler device which consists of the magnetic conductive tube 11, the pole plate 21, the bobbin 30 and a circuit board 702. Then the magnetic conductive tube 11 is held in a hole 83 of the case 82 or a conventional heat sink 86 with fins or posts(as shown in Fig. 29). The inner peripheral of magnetic conductive tube 11 is provided to contain a bearing element(not shown) for extending through a shaft 81 of impeller 80. The impeller 80 further comprises a plurality of blades 84 and permanent magnets 85. Therefore, the combined cooler device may achieve the cooling results. A brushless DC motor of the present invention as defined in Claim 1 reduces the complexity and cost of manufacture of conventional metal tube and pole plate, and reduces the thickness of a stator by means of reducing the thickness of the annular flange protruded on the outside of the pole plate.

Claims: A stator for a rotary brushless DC motor comprising: A magnetic conductive tube (10, 11, 12) made of magnetizable material and a first pole plate (101, 111, 121) formed on one end of the magnetic conductive tube, the first pole plate (101, 111, 121) further including a closed annular portion and a plurality of poles (102, 112, 122) extending therefrom; a second pole plate (20, 21, 22) sleeved to the magnetic conductive tube (10, 11, 12), held on the magnetic conductive tube (20, 21, 22) and further comprising a closed annular portion and a plurality of poles (102, 112, 122) extending therefrom; a single coil (301) wound around the magnetic conductive tube (10, 11, 12) and insulated with respect to the first and second pole plates (101, 111, 121) and located axially between the first pole plate and the second pole plate characterized in that the poles (102, 112, 122) of the first pole plate (101, 111, 121) extend axially from the closed annular portion of the first pole plate (101, 111, 121) and away from the coil to define an axial length of the poles larger than the axial thickness of the closed annular portion of the first pole plate (101, 111, 121) and in that either the poles of the second pole plate (20, 21, 22) extend only in the plane of the closed annular portion of the second pole plate (20, 21, 22) or the poles of the second pole plate (20, 21, 22) extend axially from the closed annular portion of the second pole plate (20, 21, 22) and away from the coil to define an axial length of the pole plates larger than the axial thickness of the closed annular portion of the second pole plate (20, 21, 22). The stator as defined in Claim 1, wherein the magnetic conductive tube (10, 11, 12) and a pole plate (101, 111, 121) form a single member. The stator as defined in Claim 1, wherein one end of the magnetic conductive tube (10, 11, 12) opposite said one end on which said first pole plate (101, 111, 121) is formed cylindrical. The stator as defined in Claim 1, wherein one end of the magnetic conductive tube (12, 60) opposite said one end on which said first pole plate (101, 111, 121) is formed includes an annular flange (123) having a diameter smaller than a diameter of the first pole plate (101, 111, 121). The stator as defined in Claim 1, wherein one of the pole plates (111, 21) has a recessed portion (115, 224) which forming an irregular magnetic field in order to let the stator drive the rotor easily during start-up. The stator as defined in Claim 1, wherein one of the pole plates (111, 21) has an inclined portion (114, 223) or has a first portion (114, 223) with a smaller axial thickness than a second portion of the pole plate forming an irregular magnetic field in order to let the stator drive the rotor easily during start-up. The stator as defined in Claim 1, comprising: a combined tube/plate member including the magnetic conductive tube (10, 11, 12) made of magnetizable material and the first pole plate (101, 111, 121) formed on one end of the magnetic conductive tube (10, 11, 12); and a bobbin (30, 31) made of insulating material located between the second pole plate (20, 21, 22) and the first pole plate (101, 111, 121), and insulated from the magnetic conductive tube (10, 11, 12) and the first pole plate (101, 111, 121). The stator as defined in Claim 7, wherein the bobbin (30, 31) has two discs (312) on two ends, a coil (311) being wound in between the two discs (312). The stator as defined in Claim 8, wherein the discs (312) further comprises a plurality of posts (313) arranged to fit into a plurality of holes (116, 202) on the pole plates (111, 20). The stator as defined in Claim 1, wherein a bobbin (30, 31) made of insulating material located between the second pole plate (20, 21, 22) and the first pole plate (101, 111, 121), and insulated from the magnetic conductive tube (10, 11, 12) and the first pole plate (101, 111, 121), a coil (311) being wound around the bobbin (30, 31) and insulated from the two pole plates (101, 111, 121, 20, 21, 22) and magnetic conductive tube (10, 11, 12);

Inventors: HORNG ALEX, HORNG, ALEX
Applicants: SUNONWEALTH ELECTR MACH IND CO, SUNONWEALTH ELECTRIC MACHINE INDUSTRY CO., LTD.
Application year: 1999
Main classification: H02K1
IPC codes: H02K7, H02K3, H02K29, H02K1, H02K21, H01L23