JP2007159191A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which prevents the occurrence of nonconformity that is caused by separation from the shaft of a permanent magnet or a coil which is fixed to the shaft of a rotor. <P>SOLUTION: The rotor 50 has the shaft 52 and the permanent magnet 54. A groove 102 is made at the diametrical periphery of the shaft 52. A knurled groove 104 is made at the bottom of the groove 102. The groove 102 and the knurled groove 104 are made all around the shaft 52. The permanent magnet 54 covers a recess 100 composed of the groove 102 and the knurled groove 104 at the shaft 52, by the insert molding of composite material where magnetic powder is mixed in thermoplastic resin material such as PPS, POM, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric motor, and more particularly to an electric motor used for a fuel pump.

  There is known an electric motor including a permanent magnet formed by injection molding of a composite material of a magnetic material and a resin as a magnetic field generating means of a rotor (for example, Patent Document 1). In the electric motor described in Patent Document 1, a shaft is inserted into a cylindrical through hole provided in the permanent magnet, and the permanent magnet is fixed to the shaft. However, if the through hole is deformed due to aging of the permanent magnet or the like, the coupling strength between the permanent magnet and the shaft is lowered, and the permanent magnet may be separated from the shaft. Further, in the electric motor in which the permanent magnet or the coil is attached to the resin member fixed to the shaft in the same manner as the permanent magnet described above, the permanent magnet or the coil may be separated from the shaft together with the resin member. When the permanent magnet or coil is separated from the shaft in this way, the permanent magnet or coil moves in the axial direction of the shaft, or the permanent magnet or coil rotates relative to the shaft, so that the permanent magnet or coil is attached to the shaft. Such as failure to properly transmit torque generated in the motor.

JP 2001-268874 A

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an electric motor that prevents the occurrence of problems caused by separation of a permanent magnet or a coil fixed to a rotor shaft from the shaft. To do.

  In the first to fourth aspects of the invention, the resin portion is formed on the outer peripheral wall of the shaft so as to cover the concave portion of the shaft by injection molding. Since the contact area between the shaft and the resin portion is increased by the recess, the bonding strength between the resin portion and the shaft is increased. Thereby, it can prevent that a resin part isolate | separates from a shaft. Moreover, since the resin part formed in this way is fitted in the concave part of the shaft, even if the resin part is separated from the shaft, the resin part rotates relative to the shaft or the axial direction of the shaft. Can be prevented from moving to. The resin part is a resin member that forms a rotor together with a shaft to which a permanent magnet formed of a composite material of resin and a magnetic material, for example, or a permanent magnet or a coil is attached. That is, by forming the resin portion so as to cover the concave portion of the shaft by injection molding, it is possible to prevent the occurrence of problems due to separation of the permanent magnet or the coil from the shaft.

  In the invention described in claim 2, since the recess is formed in the entire circumference of the outer peripheral wall of the shaft, the bonding strength between the resin portion and the shaft can be effectively increased. That is, it is possible to reliably prevent the occurrence of problems due to separation of the permanent magnet or coil from the shaft.

  In the third and fourth aspects of the invention, the concave portion includes a step portion formed by the small diameter portion of the shaft and a knurl formed on the outer peripheral wall of the small diameter portion of the shaft. Here, knurl grooves of general knurls such as flat knurls, twill knurls, and oblique knurls are densely formed at a predetermined angle with respect to the circumferential direction of the shaft. Therefore, the resin portion can be effectively prevented from rotating relative to the shaft by fitting the resin portion with the knurl. Furthermore, the resin portion can be prevented from moving in the axial direction of the shaft by fitting the resin portion with the stepped portion. That is, it is possible to prevent the permanent magnet or coil from rotating relative to the shaft or moving in the axial direction of the shaft.

  In the invention described in claim 4, a twill-shaped knurl is formed on the outer peripheral wall of the shaft. Since the knurled groove of the cross-shaped knurl is inclined with respect to the shaft axis, the permanent magnet or the coil rotates relative to the shaft by fitting the cross-shaped knurl and the resin portion. Moreover, it can prevent moving to the axial direction of a shaft.

  In the invention according to claims 5 to 7, the resin portion is formed on the outer peripheral wall of the shaft so as to cover the convex portion of the shaft by injection molding. Since the contact area between the shaft and the resin portion is increased by the convex portion, the bonding strength between the resin portion and the shaft is increased. Thereby, it can prevent that a resin part isolate | separates from a shaft. Further, since the resin portion formed in this manner is fitted to the convex portion of the shaft, even if the resin portion is separated from the shaft, the resin portion rotates relative to the shaft, It is possible to prevent movement in the direction. That is, by forming the resin portion so as to cover the convex portion of the shaft by injection molding, it is possible to prevent the occurrence of problems due to separation of the permanent magnet or the coil from the shaft.

  In the invention according to claim 6, since the convex portion is formed on the entire circumference of the outer peripheral wall of the shaft, the coupling strength between the resin portion and the shaft can be effectively increased. That is, it is possible to reliably prevent the occurrence of problems due to separation of the permanent magnet or coil from the shaft.

  In the invention according to claim 7, the permanent magnet or the coil can be rotated relative to the shaft in the axial direction of the shaft by fitting the resin portion with the protruding portion protruding in the radial direction of the shaft. It is also possible to prevent movement.

  In the invention according to claim 8, since the permanent magnet is formed on the outer peripheral wall of the shaft by the composite material including the resin and the magnetic material by injection molding, it is possible to prevent the occurrence of trouble due to the separation of the permanent magnet from the shaft. Can do.

  According to the ninth aspect of the present invention, the permanent magnet of the rotor is separated from the shaft together with the resin member by attaching the permanent magnet to the resin portion that is prevented from being separated from the shaft or moved relative to the shaft. Occurrence can be prevented.

  In the invention according to claim 10, by attaching the coil to the resin portion that prevents separation from the shaft and relative movement with respect to the shaft, the occurrence of a malfunction due to separation of the rotor coil from the shaft together with the resin member is prevented. Can be prevented.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In each of the embodiments, the component having the same reference sign corresponds to the component of the other embodiment having the reference sign.
(First embodiment)
A fuel pump according to a first embodiment of the present invention is shown in FIG. The fuel pump 10 of the present embodiment is an in-tank type turbine pump installed in a fuel tank of a two-wheeled vehicle having a displacement of 150 cc or less, for example.
The fuel pump 10 includes a pump unit 12 and a motor unit 13 that rotationally drives the pump unit 12. The housing 14 is formed in a cylindrical shape by pressing a metal thin plate of about 0.5 mm, and also serves as a housing for the pump unit 12 and the motor unit 13. The housing 14 formed of a thin plate forms a protrusion 16 that is recessed on the inner peripheral side between the pump portion 12 and the motor portion 13.

  The pump unit 12 is a turbine pump having pump cases 20 and 22 and an impeller 24. The pump case 22 is press-fitted into the housing 14 and abuts against the protrusion 16 of the housing 14 in the axial direction. Thereby, the axial positioning of the pump case 22 is achieved. The pump case 20 is fixed by caulking at one end side of the housing 14.

  The pump cases 20 and 22 are pump cases that accommodate the impeller 24 rotatably. C-shaped fuel passages 70 are formed between the pump cases 20 and 22 and the impeller 24, respectively. Fuel sucked from a suction port (not shown) provided in the pump case 20 is pressurized in the fuel passage 70 by the rotation of the impeller 24 and is pumped to the motor unit 13 side. The fuel pumped to the motor unit 13 side passes through a fuel passage 72 between the stator core 30 and the rotor 50, and from a discharge port 74 formed on the opposite side to the pump unit 12 in the axial direction with respect to the motor unit 13. Supplied to the engine side.

  The motor unit 13 as an electric motor is a so-called brushless motor, and includes a stator core 30, a bobbin 40, a coil 42, and a rotor 50. The stator core 30 as a stator is configured by installing six cores 32 in the circumferential direction. A control device (not shown) performs three-phase full-wave control of energization of the coil 42 according to the rotational position of the rotor 50, thereby switching the magnetic poles formed on the inner peripheral surface of each core 32 facing the rotor 50.

  Each core 32 is fitted with a bobbin 40 formed of an insulating resin. The coil 42 is formed by concentrating windings around the bobbin 40 in a state where each core 32 before assembling the fuel pump 10 is a single body. Each coil 42 is electrically connected to the terminal 44 on the end cover 48 side.

  The rotor 50 has a shaft 52 and a permanent magnet 54, and is rotatably installed on the inner periphery of the stator core 30. Both end portions of the shaft 52 are rotatably supported by the bearing 26. A recess 100 is formed in the outer peripheral wall 53 of the shaft 52. Specifically, for example, as shown in FIG. 2, the recess 100 is constituted by a stepped portion 103 formed by the small diameter portion 102 of the shaft 52 and a knurled groove 104 formed on the outer peripheral wall of the small diameter portion 102. Yes.

  The permanent magnet 54 as the resin portion is formed so as to cover the concave portion 100 of the shaft 52 by injection molding of a composite material in which magnetic powder is kneaded into a thermoplastic resin material such as PPS (polyphenylene sulfide) or POM (polyacetal). Cylindrical plastic magnet. The permanent magnet 54 forms eight magnetic pole portions 55 in the rotation direction. The eight magnetic pole portions 55 are magnetized so as to form different magnetic poles alternately in the rotational direction on the outer peripheral surface facing the stator core 30.

  The insulating resin material 46 is integrally formed with an end cover 48 that covers each coil 42 and covers the end of the stator core 30 opposite to the pump portion 12. The end 15 of the housing 14 is press-fitted into the outer peripheral surface 49 of the end cover 48.

  A valve member 60, a stopper 62 and a spring 64 are accommodated in the discharge port 74 formed by the end cover 48. When the fuel pressurized by the pump unit 12 reaches a predetermined pressure or higher, the valve member 60 lifts against the load of the spring 64 and the fuel is discharged from the discharge port 74 to the engine side.

  As shown in FIG. 2, in the first embodiment, the concave portion 100 is formed in the shaft 52, and the permanent magnet 54 covers the concave portion 100. Since the contact area between the shaft 52 and the permanent magnet 54 is increased by the step portion 103 and the knurled groove 104, the coupling strength between the shaft 52 and the permanent magnet 54 can be increased.

  Further, since the permanent magnet 54 is directly formed on the outer peripheral wall 53 of the shaft 52 by injection molding, the shape of the concave portion 100 of the shaft 52 is transferred to the shaft 52 side of the permanent magnet 54. As a result, since the permanent magnet 54 and the concave portion 100 of the shaft 52 are fitted, even if the permanent magnet 54 is separated from the shaft 52, the permanent magnet 54 does not move relative to the shaft 52. Specifically, the permanent magnet 54 and the step 103 can be fitted together to prevent the permanent magnet 54 from moving in the axial direction of the shaft 52, and the permanent magnet 54 and the knurled groove 104 can be fitted together. The permanent magnet 54 can be prevented from rotating relative to the shaft 52.

  Note that the knurled groove 104 may be a cross-shaped knurled groove illustrated in FIG. 1, a flat knurled groove illustrated in FIG. 3, or an oblique knurled groove.

  Further, the rotor 50 may be constituted by a shaft 52 on which the convex portion 200 is formed and a permanent magnet 54 that covers the convex portion 200. Specifically, for example, a protruding portion 202 protruding in the radial direction of the shaft 52 may be formed on the shaft 52 as the protruding portion 200 (see FIG. 4). In this case, the permanent magnet 54 is fitted to the protruding portion 202, thereby preventing the permanent magnet 54 from rotating relative to the shaft 52 and preventing the permanent magnet 54 from moving in the axial direction of the shaft 52. be able to. Moreover, the convex part 200 may have the knurled groove | channel 104 in the top part (refer FIG. 6 (A)).

Moreover, the recessed part 100 or the convex part 200 may be formed in a part of the outer peripheral wall 53 of the shaft 52, and does not need to be formed in the perimeter of the outer peripheral wall 53 of the shaft 52 (refer FIG. 5).
In addition, as shown in FIGS. 6B and 6C, the recess 100 may have a step 112 and a step 114 formed on one side of the shaft 52 of the knurled groove 104 in the axial direction.

(Second Embodiment)
The fuel pump according to the second embodiment of the present invention differs from the fuel pump 10 according to the first embodiment in the configuration of the rotor of the motor unit. The other components of the fuel pump according to the second embodiment of the present invention are substantially the same as the corresponding components of the fuel pump 10 according to the first embodiment.

  The rotor 250 of the motor unit according to the second embodiment of the present invention shown in FIG. 7 has a shaft 52, a mounting member 256, and a permanent magnet 254. The attachment member 256 as the resin portion is formed so as to cover the concave portion 100 of the shaft 52 by injection molding of a thermoplastic resin material such as PPS or POM or a composite material containing a thermoplastic resin material. A permanent magnet 254 is attached to the attachment member 256. The permanent magnet 254 is magnetized so as to form a magnetic pole similar to the permanent magnet 54 according to the first embodiment.

  In the second embodiment, the attachment member 256 covers the recess 100 of the shaft 52. In this case, the contact area between the shaft 52 and the mounting member 256 is increased by the step portion 103 and the knurled groove 104, so that the coupling strength between the mounting member 256 to which the permanent magnet 54 is mounted and the shaft 52 can be increased. it can.

  Further, since the mounting member 256 is directly formed on the outer peripheral wall 53 of the shaft 52 by injection molding, the shape of the concave portion 100 of the shaft 52 is transferred to the shaft 52 side of the mounting member 256. As a result, the permanent magnet 54 rotates relative to the shaft 52 together with the mounting member 256 even if the mounting member 256 is separated from the shaft 52 in order to fit the mounting member 256 and the recess 100 of the shaft 52. It does not move in the axial direction of the shaft 52 together with the mounting member 256.

(Third embodiment)
The fuel pump according to the third embodiment of the present invention is practically the same as the fuel pump 1 according to the first embodiment except for the motor unit. The motor part of the fuel pump according to the third embodiment of the present invention is a so-called brushed motor, and is substantially the same as a general brushed motor except for the configuration of the rotor. Hereinafter, the rotor of the motor unit will be described.
A rotor 350 of the motor unit illustrated in FIG. 8 includes a shaft 52, a mounting member 356, and a coil 354. The attachment member 356 as the resin portion is injection-molded on the shaft 52 in the same manner as the attachment member 256 according to the second embodiment. A plurality of coils 354 are attached to the attachment member 356 in the rotational direction of the rotor 350. The coil 354 is delta-connected, and the coil 354 adjacent to the rotation direction is wound in the reverse direction.

  Therefore, the coupling strength between the attachment member 356 and the shaft 52 to which the coil 354 is attached can be increased. Further, the coil 354 can be prevented from rotating relative to the shaft 52 together with the mounting member 356, and the coil 354 can be prevented from moving in the axial direction of the shaft 52 together with the mounting member 256.

(Other examples)
In the above embodiments, the embodiment in which the present invention is applied to the fuel pump has been described. However, the present invention is not limited to this and can be applied to various electric motors. The fuel pump is not limited to a gasoline engine, but may be a diesel engine or an alcohol fuel.

  Further, the concave portion 100 and the convex portion 200 of the shaft 52 are not limited to the illustrated shapes, and separation of the permanent magnet 54, the permanent magnet 254, or the coil 354 from the shaft 52 can be prevented, and the permanent magnet 54, the permanent magnet 254, or the coil can be prevented. Any shape may be used as long as relative movement of the 354 relative to the shaft 52 can be prevented.

  In the second embodiment, the mounting member 256 and the permanent magnet 254 may be formed on the outer peripheral wall 53 of the shaft 52 by two-stage injection molding. At this time, a concave portion or a convex portion similar to the concave portion 100 or the convex portion 200 of the shaft 52 is formed on the attachment member 256, thereby increasing the coupling strength between the attachment member 256 and the permanent magnet 254, so that the permanent magnet 254 is attached to the attachment member 256. It may be prevented from coming off.

  As described above, the present invention is not limited to the above-described plurality of embodiments, and can be applied to various embodiments without departing from the gist thereof.

Sectional drawing which shows the fuel pump by 1st Embodiment. The schematic diagram of the uneven | corrugated | grooved part vicinity of the shaft which concerns on 1st Embodiment. The schematic diagram for demonstrating the modification of the fuel pump by 1st Embodiment. The schematic diagram for demonstrating the modification of the fuel pump by 1st Embodiment. The schematic diagram for demonstrating the modification of the fuel pump by 1st Embodiment. The schematic diagram for demonstrating the modification of the fuel pump by 1st Embodiment. The schematic diagram for demonstrating the fuel pump by 2nd Embodiment. The schematic diagram for demonstrating the fuel pump by 3rd Embodiment.

Explanation of symbols

13: Motor part (electric motor), 30: Stator core (stator), 42, 354: Coil, 50, 250, 350: Rotor, 52: Shaft, 54: Permanent magnet, 100: Recess, 103, 112, 114: Stepped portion (recessed portion), 104: knurled groove (recessed portion), 200: raised portion, 202: protruding portion, 254: permanent magnet, 256, 354: coil, 356: mounting member (resin portion)

Claims (10)

A stator and a rotor rotatably installed on the inner peripheral side of the stator,
The rotor has a shaft having a recess in the outer peripheral wall, and a resin portion that covers the recess by injection molding of a resin or a composite material containing resin,
An electric motor characterized by that. The recess is provided on the entire circumference of the outer peripheral wall,
The electric motor according to claim 1. The shaft has a small diameter portion;
The concave portion includes a step portion formed by the small diameter portion and a knurl formed on an outer peripheral wall of the small diameter portion.
The electric motor according to claim 1 or 2. The knurling is a twill-shaped knurling,
The electric motor according to claim 3. A stator and a rotor installed rotatably on the inner peripheral side of the stator,
The rotor has a shaft having a convex portion on an outer peripheral wall, and a resin portion covering the convex portion by injection molding of resin or a composite material containing resin.
An electric motor characterized by that. The convex portion is provided on the entire circumference of the outer peripheral wall,
The electric motor according to claim 5. The protrusion has a protrusion protruding in the radial direction of the shaft.
The electric motor according to claim 5 or 6. The resin portion is a permanent magnet formed of a composite material including a resin and a magnetic material.
The electric motor according to any one of claims 1 to 7. The rotor further includes a permanent magnet attached to the resin portion.
The electric motor according to any one of claims 1 to 7. The rotor further includes a coil that is attached to the resin portion and whose magnetic pole is switched in the rotation direction by being energized.
The electric motor according to any one of claims 1 to 7.

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