JP2012016226A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which is preferable for reducing a size and thickness of office automation equipment.SOLUTION: In a motor 10, a bearing holding member 42 is made of a metal material, and a metal layer 432, exposed to the outmost surface, is provided at an end portion of an opening 431 of a circuit board 43. An adhesive, which cures by that catalytic reaction is induced by a contact with metal ions, is disposed in an area where the bearing holding member 42 contacts with the metal layer 432.

Description

  The present invention relates to a motor, and more particularly to a motor that is mounted on an OA device and that is required to have a small size and high output.

  Conventionally, as a method for fixing the bearing holding member of the motor and the circuit board, a method using a fixing means using a fixing member using a screw has been generally used.

JP-A-10-108414

  In recent years, as office automation equipment has become smaller and thinner, motors have been required to be smaller and thinner. At the same time, there is a demand for lower motor prices.

  Referring to FIGS. 1 and 2 of Patent Document 1 (Japanese Patent Laid-Open No. 10-108414) regarding the structure of a conventional motor, a through hole is formed in the motor housing portion 20 at several flat portions overlapping in the axial direction with the printed circuit board 16. Is provided. A through hole is also formed in the printed circuit board 16 so as to correspond to the through hole. In these through-holes, grooves that are screwed with threads are formed, and screws 17 are inserted therethrough. Thereby, the housing part 20 and the printed circuit board 16 are fastened and fixed. However, in this structure, it is necessary to secure a fastening space for inserting the screw 17 into the housing part 20 or the printed board 16. For this reason, the above-described motor cannot be reduced in size and thickness. Further, since the screws 17 are necessary for fastening, there is a problem that the manufacturing cost of the motor rises and the price of the motor cannot be reduced.

  According to the first aspect of the present invention, the shaft disposed along the central axis, the rotor holder that rotates together with the shaft, and has a lid portion and a cylindrical portion, and the substantially fixed to the inner peripheral surface of the cylindrical portion. A cylindrical rotor magnet; a bearing member that rotatably supports the shaft at a lower side in the axial direction than the lid; a substantially cylindrical bearing holding member that holds the bearing member on an inner peripheral surface; A stator disposed radially outside the bearing holding member and facing the rotor magnet in the radial direction, and an opening through which the bearing holding member is inserted in the center, the bearing being below the stator in the axial direction A circuit board fixed to the holding member, wherein the bearing holding member is formed of a metal material, and an end portion of the opening of the circuit board is exposed to the outermost surface. An adhesive layer that has a metal layer and is in contact with the metal layer made of the metal material of the circuit board is in contact with a metal ion to induce a catalytic reaction and harden. Features.

  According to claim 1 of the present invention, a bare metal layer is formed on the outermost surface at the end of the opening where the circuit board contacts the bearing holding member. The bearing holding member is also made of a metal material. Therefore, an anaerobic adhesive that cures using metal ions as a catalyst can be used for fixing the bearing holding member and the circuit board.

  ADVANTAGE OF THE INVENTION According to this invention, the motor which implement | achieved size reduction and thickness reduction can be provided, without increasing the number of parts of a motor.

FIG. 1 is a schematic cross-sectional view of the motor cut in the axial direction. FIG. 2 is a plan view of the bush. FIG. 3 is a bottom view of the circuit board.

<Overall structure of motor>
In the present specification, in the direction of the central axis J1, the upper side in the figure is simply called “upper side”, and the lower side in the figure is simply called “lower side”. The expressions “upper” and “lower” do not necessarily coincide with the direction of gravity.

  An embodiment of the motor according to the present invention will be described with reference to FIG. FIG. 1 shows an embodiment of a motor according to the present invention, and is a schematic cross-sectional view when virtually cut in the axial direction.

  The motor 10 includes a rotating unit 20 that rotates about a central axis J1, a bearing member 30 that rotatably supports the rotating unit 20, and a stationary unit 40 that holds two bearing members.

  The rotating part 20 is arranged coaxially with the central axis J1 and has a substantially cylindrical shaft 21 extending along the axial direction, a rotor holder 22 fixed to the upper side of the shaft 21 in the axial direction, and a rotor magnet fixed to the rotor holder 22. 23.

  The axially lower side of the shaft 21 is a gear portion 211 in which a plurality of grooves are formed. By engaging the gear portion 211 and an external device, the torque of the motor 10 can be output to the outside. it can.

  The rotor holder 22 has a substantially cylindrical shape with a lid, a shaft fixing portion 221 that is fixed to the shaft 21, a substantially disk-shaped lid portion 222 that extends radially outward from the shaft fixing portion 221, and the radial direction of the lid portion 222. A substantially cylindrical portion 233 extending from the outer edge toward the lower side in the axial direction. The rotor holder 22 is formed, for example, by punching a thin plate-like magnetic material by pressing.

  A substantially cylindrical rotor magnet 23 is fixed to the inner peripheral surface of the cylindrical portion 233 of the rotor holder 22. The rotor magnet 23 is magnetized for field. Further, the lower surface of the rotor magnet 23 is magnetized for position detection.

  An upper bearing 31 and a lower bearing 32 are fixed to the outer peripheral surface of the shaft 21. The upper bearing 31 and the lower bearing 32 constitute a bearing member 30.

  The stationary portion 40 is disposed on the lower side in the axial direction of the stator 41, a substantially cylindrical bush 42 formed so as to be coaxial with the central axis J <b> 1, a stator 41 fixed to the outer peripheral surface of the bush 42. A circuit board 43 fixed to the bush 42.

  FIG. 2 is a plan view of the bush 42. Hereinafter, a description will be given with reference to FIG. The bush 42 constitutes a bearing holding member, and the upper bearing 31 and the lower bearing 32 are held on the inner peripheral surface thereof by insertion or a combination of insertion and adhesion. The bush 42 is formed by molding a metal material such as an aluminum alloy or a zinc alloy by a die casting method. The outer peripheral surface of the bush 42 is a first cylindrical portion 421 located on the upper side in the axial direction, a second cylindrical portion 422 located on the lower side of the first cylindrical portion 421 and having a larger outer diameter than the first cylindrical portion 421, The flange portion 423 is disposed below the second cylindrical portion 422 and extends in a direction substantially perpendicular to the central axis J1.

  On the upper side of the first cylindrical portion 421, the stator fixing portion 424 is arranged at three intervals in the circumferential direction with a space.

  The second cylindrical portion 422 has guide portions 425 that are arranged at intervals at three locations in the circumferential direction, and the distance from the central axis J1 in the radial direction gradually increases as they go downward in the axial direction. In addition, below the second cylindrical portion 422, substrate fixing portions 426 are disposed at intervals at three locations in the circumferential direction. In the radial direction, the distance from the central axis J1 to the outermost part of the substrate fixing part 426 is equal to or smaller than the distance from the central axis J1 to the outermost part of the guide part 425.

  The flange portion 423 has an upper surface that is flush with a direction perpendicular to the central axis J1. In addition, the flange portion 423 includes three arm portions 4231 that are arranged at three positions at intervals in the circumferential direction and extend radially outward. Each arm portion 4231 is provided with a fixing hole 4232 that opens in the axial direction. A fixing member (not shown) such as a screw is inserted into the fixing hole 4232 so that the motor 10 can be fixed to the apparatus main body. The flange portion 423 includes a positioning portion 4233 extending outward in the radial direction, and a positioning projection 4234 that protrudes upward in the axial direction is disposed on the positioning portion 4233.

  The stator 41 is formed by laminating a plurality of magnetic steel plates. The stator 41 includes a stator core 411 having an annular core back portion 4111 and a plurality of tooth portions 4112 extending radially outward from the core back portion 4111, and a coil 412 wound around each tooth portion 4112. .

  The circuit board 43 is made of glass epoxy resin. An opening 431 penetrating in the axial direction is provided at the center of the circuit board 43. The second cylindrical portion 422 of the bush 42 is inserted through the opening 431. In addition, a slit 4311 is formed at the end of the opening 431 so as to be cut outward in the radial direction. A positioning projection 4234 is inserted into the slit 4311.

  Lands (not shown) corresponding to the U-phase, V-phase, and W-phase are arranged on the lower surface of the circuit board 43, and a conductive wire (not shown) drawn from the coil 412 of the stator 41 is soldered to each land. Attached.

  On the lower surface of the circuit board 43, a Hall element (not shown) that detects the rotational position of the rotating unit 20 by a change in the magnetic field is disposed.

  An FG pattern is disposed on the upper surface of the circuit board 43. The FG pattern is arranged to face the rotor magnet 23 in the axial direction. The FG pattern induces a voltage to generate an FG signal by a change in the magnetic field of the rotor magnet 23 accompanying the rotation of the rotating unit 20. By reading the FG signal, the rotational position and speed of the rotating body 20 are detected.

  A land portion (not shown) to which a flexible flat cable (not shown) connected to an external power source or the like is soldered is disposed on the circuit board 43.

  On the lower surface of the circuit board 43, a metal layer 432 is formed around the end of the opening 431. The metal layer 432 is formed in substantially the same shape as the flange portion 423 when the bush 42 is orthographically projected. (See FIG. 3). In the present embodiment, the metal layer 432 is a copper foil, and can be formed at the same time as the substrate pattern is printed when the substrate pattern is printed on the circuit board. Therefore, when the metal layer 432 is formed, no additional processing steps or parts are required, and costs and process time can be reduced.

<Fixing structure between bush and circuit board>
The circuit board 43 is placed on the flange portion 423. An adhesive is interposed between the gold layer 432 of the circuit board 43 and the upper surface of the flange portion 423. As the adhesive, for example, an adhesive that induces a catalytic reaction and hardens when contacted with metal ions can be used. As such an adhesive material, for example, an anaerobic adhesive such as an acrylic resin anaerobic adhesive is used. On the upper surface of the circuit board 43, the board fixing part 426 is bent outward in the radial direction at the end of the opening 431. As a result, the circuit board 43 is fixed while being sandwiched between the board fixing part 426 and the flange part 423. The circuit board 43 can be firmly fixed to the bush 42 by using both the fixing by the clamping and the fixing by the above-described adhesive.

  In this regard, conventionally, the circuit board 43 and the bush 42 are fixed using a fixing member such as a screw. However, when the fixing member is used, there is a problem that the number of parts is increased and the assembling workability is deteriorated. On the other hand, in the case of fixing only by clamping, there is a problem in terms of reliability because the fixing may be loosened due to creep. Further, in the case of fixing only by adhesion, there is a problem in terms of reliability due to deterioration of the adhesive or the like in a use environment where temperature change is severe.

  Although it is conceivable to use an adhesive other than the anaerobic adhesive, there are the following problems. For example, in the case of a two-component adhesive, a separate process is required at the time of applying the adhesive, resulting in poor workability. Moreover, if it is an instant adhesive, since hardening time is quick, process control is difficult. Moreover, since the epoxy adhesive generally has a high viscosity, workability is poor. However, the above problem does not occur with an anaerobic adhesive.

  As described above, in the present embodiment, since the circuit board 43 and the bush 42 are fixed by using both clamping and adhesion, the number of parts can be reduced without impairing reliability. Further, since the pattern on the circuit board is used, additional processing steps, parts, and the like are unnecessary, and the cost can be reduced.

<Motor assembly process>
Next, the assembly process of the motor will be described.

  First, a description will be given with reference to FIG. First, an anaerobic adhesive is applied to the adhesive application region 427 of the bush 42. The adhesive application region 427 is provided in a substantially annular shape. The adhesive is applied with a dispenser.

  Next, the bush 42 is inserted into the opening 431 of the circuit board 43. At this time, the circuit board 43 is guided by the guide part 425 disposed outside the second cylindrical part 422 of the bush 42 so that the central axis J1 and the opening part 431 are coaxial. Further, the guide portion 425 prevents the circuit board 43 from riding on the substrate fixing portion 426. The bush 42 inserted into the opening 431 is inserted until the lower surface of the circuit board 43 contacts the upper surface of the flange portion 423. At this time, the positioning protrusion 4234 is inserted into the slit 4311 of the opening 431. Thereby, the circumferential position of the bush 42 and the circuit board 43 is positioned. As described above, the metal layer 432 formed on the lower surface of the circuit board 43 is formed in substantially the same shape as the flange portion 423 when the bush 42 is orthographically projected. Therefore, the metal layer 432 is positioned so as to coincide with the position of the flange portion 423. As a result, the circuit board 43 contacts the flange portion 423 of the bush 42 at the metal layer 432.

  When the bush 42 is inserted into the opening 431, the metal layer 432 and the flange portion 423 are in contact with each other. The anaerobic adhesive applied to the adhesive application region 427 of the bush 42 extends into a fine gap formed between the metal layer 432 and the flange portion 423 due to capillary action. Here, the anaerobic adhesive is blocked from the outside air and comes into contact with metal ions (that is, the metal bushing 42 and the metal layer 432). Therefore, in an anaerobic adhesive, a catalytic reaction is induced and its curing starts. In this state, the board fixing portion 426 is bent outward in the radial direction at the end of the opening 431 so as to contact the upper surface of the circuit board 43. As a result, the circuit board 43 is fixed while being sandwiched between the board fixing part 426 and the flange part 423. Even after the substrate fixing portion 426 is bent, the catalytic reaction of the anaerobic adhesive continues and eventually completely cures.

  Next, an anaerobic adhesive is applied to the outer peripheral surface of the first cylindrical portion 421 of the bush 42. The adhesive is applied with a dispenser.

  Then, the first cylindrical portion 421 of the bush 42 is inserted inside the core back 4111 of the stator 41. Thereby, the anaerobic adhesive applied to the outer peripheral surface of the first cylindrical portion 421 spreads between the outer peripheral surface of the first cylindrical portion 421 and the core back 4111. Since the first cylindrical portion 421 and the core back 4111 are metal, the curing of the adhesive starts as described above. The lower surface of the core back 4111 is in contact with the upper end surface of the second cylindrical portion 422. In this state, the stator fixing portion 424 is bent radially outward and brought into contact with the upper surface of the core back 4111. Thereby, the stator 41 is fixed in a state of being sandwiched between the upper end surface of the second cylindrical portion 422 and the stator fixing portion 424.

  Finally, the bearing member 30 is fixed to the inside of the bush 42, and the rotating unit 20 is inserted to complete the motor.

  Although one embodiment according to the present invention has been described above, the present invention is not limited to this.

  For example, the metal layer 432 need not be formed over the entire periphery of the opening 431. You may form in the multiple places in the circumferential direction. Also in this case, the formation locations are desirably arranged at equal intervals, but may not be equal intervals.

  The number of slits 4311 formed in the opening 431 is not limited to one, and a plurality of slits 4311 may be formed. Further, the number of positioning protrusions 4234 may be increased accordingly. If the number of slits 4311 is larger, the number of positioning protrusions 4234 need not match that of the slits 4311.

  The number of substrate fixing parts 426 is not limited to three. For example, the number of substrate fixing parts 426 may be one, and it may be formed in a flange shape so as to cover the entire end of the opening 431. Further, the number of substrate fixing portions can be 2 to 4 or more. Further, the positions of the plurality of substrate fixing portions 426 are not necessarily equal.

  Also, regarding the application of the adhesive, it is not always necessary to apply the adhesive to the entire region in the metal layer 432, the first cylindrical portion 421, and the adhesive application region 427. An adhesive may be applied to a plurality of locations, or at least the adhesive may spread over the applied locations.

  The adhesive application region 427 does not necessarily have a substantially annular shape, and a plurality of fan-shaped regions may be formed.

  The number of arm portions 4231 is not limited to three.

  The circuit board 43 may be made of paper phenol.

  The present invention is applicable not only to an outer rotor type motor but also to an inner rotor type motor. In this case, an adhesive application region such as copper foil is formed on the outer peripheral surface of the circuit board, and the circuit board is accommodated in the housing.

DESCRIPTION OF SYMBOLS 10 Motor 20 Rotating part 30 Bearing member 40 Static part 41 Stator 42 Bush 421 1st cylindrical part 422 2nd cylindrical part 423 Flange part 424 Stator fixing part 425 Guide part 426 Substrate fixing part 427 Adhesive application area 431 Opening part 432 Metal layer J1 central axis

Claims (6)

A shaft disposed along the central axis;
A rotor holder that rotates with the shaft and has a lid portion and a cylindrical portion;
A substantially cylindrical rotor magnet fixed to the inner peripheral surface of the cylindrical portion;
A bearing member rotatably supporting the shaft on the lower side in the axial direction than the lid portion;
A substantially cylindrical bearing holding member in which the bearing member is held on an inner peripheral surface;
A stator disposed radially outside the bearing holding member and facing the rotor magnet in the radial direction;
A circuit board having an opening through which the bearing holding member is inserted at the center, and being fixed to the bearing holding member below the stator in the axial direction;
A motor comprising:
The bearing holding member is formed of a metal material,
At the end of the opening of the circuit board has a bare metal layer on the outermost surface,
The motor according to claim 1, wherein an adhesive that induces a catalytic reaction and hardens when contacted with metal ions is interposed in at least a part of a portion where the bearing holding member contacts the metal layer. The motor according to claim 1, wherein
The motor according to claim 1, wherein the bearing holding member includes a board fixing portion for fixing and holding the circuit board. The motor according to claim 1 or 2,
On one side in the axial direction of the circuit board with the shaft as the center, a portion with which the board fixing portion formed on the bearing holding member abuts is formed,
The motor, wherein the bearing holding member and the circuit board are fixed via the adhesive on the other side of the circuit board in the axial direction. The motor according to any one of claims 1 to 3,
The board holding portion formed on the bearing holding member is provided on one side in the axial direction centered on the shaft, and the bearing holding member and the circuit board are in the same direction as the one side in the axial direction. A motor fixed by the adhesive. The motor according to claim 1, wherein
The motor according to claim 1, wherein the metal layer of the circuit board is formed on at least a part of the end of the opening in the circuit board. The motor according to claim 1, wherein
The motor according to claim 1, wherein the metal layer of the circuit board is formed over the entire circumference of the end of the opening of the circuit board.

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