JP2009180294A - Dynamic pressure bearing motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost in a dynamic pressure bearing motor and secure a dynamic pressure bearing section having highly accurately with stable strength without considering the bearing temperature when the motor is used. <P>SOLUTION: The dynamic pressure bearing section 150 is disposed in a resin-made housing 110 having an opening at one end so that a rotary shaft 140 is rotatably supported in the dynamic pressure bearing section 150. A herringbone-grooved part is formed on the inner peripheral surface of the dynamic pressure bearing section 150, and lubricating oil is distributed between the dynamic pressure bearing section 150 and the rotary shaft 140. A cap 190 is mounted so that an upper end portion of the dynamic pressure bearing section 150 in the housing 110 is covered. The cap 190 is externally fitted by inserting into the outer peripheral surface of the upper end part of the dynamic pressure bearing section 150 on the inner peripheral surface of a cylindrical wall section drooping from the outer peripheral edge of a lid upper section to close the opening, and internally fitted and secured into the inner peripheral surface of the opening of the housing 110 on the outer peripheral surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fluid dynamic bearing type motor in which a fluid such as oil or air is interposed between a rotating shaft and a bearing.

  Conventionally, outer rotor type spindle motors such as magnetic disk devices such as HDD and FDD, optical disk devices such as CD-ROM and DVD-ROM, and magneto-optical disk devices such as MD and MO, use a dynamic pressure bearing type motor. ing.

  In the structure of the dynamic pressure bearing, a bearing portion in which a dynamic pressure groove is formed on the inner peripheral surface is used as a bearing portion that is fixed by being press-fitted into the stator-side housing and into which the rotor shaft is inserted. The bearing portion holds the lubricating oil in a bearing gap formed with the rotor shaft, thereby supporting the rotor shaft by utilizing a dynamic pressure effect generated in the lubricating oil by the dynamic pressure groove during rotation. The dynamic pressure bearing type can support the rotor shaft in a non-contact state by a lubricating oil film so that it can rotate freely, and is superior in terms of vibration and noise characteristics compared to a rolling bearing type motor that has been applied to spindle motors. Yes.

In a hydrodynamic bearing type motor, the cylindrical housing that holds the bearing portion generally withstands the temperature range of the bearing portion (also referred to as the motor operating temperature range or the bearing temperature) due to the rotation of the rotor shaft when the motor is driven. Due to the necessity of high strength, etc., it is made of a soft metal material such as brass or a metal material such as leadless brass (see Patent Document 1 or Patent Document 2). In Patent Document 1 or Patent Document 2, a sealing material for preventing oil leakage is disposed in the housing in a state where the rotor shaft is inserted above the bearing portion.
JP 2005-172244 A JP 2003-172336 A

  By the way, in the conventional dynamic pressure bearing type motor shown in Patent Document 1 or Patent Document 2, there is a demand to change the housing to metal and mold it with resin in order to reduce the manufacturing cost.

  In a conventional dynamic pressure bearing type motor structure including a housing that holds a bearing portion by press-fitting, when the housing is made of resin, when the rotor shaft rotates, the resin housing itself increases as the temperature of the bearing portion increases. The temperature rises. As a result, the housing itself is deformed, and a gap is formed in the press-fitted portion between the inner peripheral surface of the housing and the outer peripheral surface of the bearing portion, which may reduce the holding force of the bearing portion.

  On the other hand, when the pressure input to the housing of the bearing portion is increased to increase the holding force of the housing, stress is applied to the bearing portion from the outer peripheral surface, the inner diameter is changed, and the dynamic pressure groove formed on the inner peripheral surface There is a problem that there is a risk of disturbing the dynamic pressure action due to.

  The present invention has been made in view of the above points, and can reduce the cost and fix the hydrodynamic bearing portion with high accuracy and stable strength without considering the bearing temperature when using the motor. An object of the present invention is to provide a hydrodynamic bearing motor.

  The hydrodynamic bearing motor of the present invention includes a resin housing having an opening at one end, a cylindrical inner peripheral surface, a bearing portion fitted into the housing through the opening, and a bearing portion. A rotor shaft inserted rotatably, a dynamic pressure generating groove formed on at least one of an inner peripheral surface of the bearing portion and an outer peripheral surface of the rotor shaft facing the inner peripheral surface, and an inner peripheral surface of the bearing portion And a lubricant for generating dynamic pressure held between the rotor shaft and the outer peripheral surface of the rotor shaft, and the rotor shaft is rotatably inserted, fixed to the opening side of the housing, and the insertion direction of the bearing portion A cap attached to the upper end of the opposite side so as to cover the upper end and restricting the movement of the bearing in the thrust direction, the cap being inserted with the rotor shaft, and the opening Close A lid upper surface portion and a cylindrical shape that hangs down from the outer peripheral edge of the lid upper surface portion, and is fitted on the outer peripheral surface of the upper end portion of the bearing portion by press fitting at the inner peripheral surface, and at the outer peripheral surface, The structure which has a cylindrical wall part internally fitted by the internal peripheral surface of the said opening part is taken.

  According to the present invention, the cost can be reduced, and the hydrodynamic bearing portion can be held with high accuracy and stable strength without considering the bearing temperature when the motor is used.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a main part showing a configuration of a fluid dynamic bearing motor according to an embodiment of the present invention. Note that FIG. 1 shows a cross-section of the main part of different parts on the left and right with the rotation axis C interposed therebetween.

  The hydrodynamic bearing motor 100 according to the present embodiment will be described as being used as an exhaust fan motor that is attached to an electronic device such as a projector or a PC. For example, you may use as a spindle motor etc. which rotate the disk (disk part) of a hard disk drive (Hard Disc Drive).

  In the hydrodynamic bearing motor 100, a stator 120 is provided on the outer periphery of a bottomed cylindrical housing 110 in which an opening is formed at one end standing from the center of a flat plate-like pedestal. In addition, a rotor shaft 140 of a rotor 130 including an impeller 132 is rotatably inserted into the housing 110 via a dynamic pressure bearing portion 150 fitted in the housing 110.

  The housing 110 is made of resin, and the pedestal is formed by a flange 102 projecting radially outward from the outer peripheral surface of the base end portion 110 a of the housing 110, and is formed by integral molding with the housing 110. The bottom surface of the pedestal and the bottom surface of the housing 110 are on the same plane. A substrate 103 for controlling the hydrodynamic bearing motor 100 is disposed on the upper surface of the pedestal (flange) 102 along the outer peripheral surface of the cylindrical housing 110.

  In the housing 110, the inner peripheral surface disposed on the outer periphery of the hydrodynamic bearing portion 150 is formed so as to retreat stepwise from the bottom side toward the upper side with respect to the shaft center. A part accommodating part 111, a bearing accommodating part 112, a cap accommodating part 113, and an adhesive layer forming part 114 are defined. A shaft receiving washer 116 with which the tip 141 of the rotor shaft 140 abuts is disposed on the bottom of the housing 110, in other words, on the inner bottom 115 of the shaft tip receiving portion 111.

  The bottom portion 117 of the housing 110 has an axial thickness, and in this bottom portion 117, an attracting magnet 170 is disposed on the axis C of the rotor shaft 140 and attracts the rotor shaft 140 to the bottom surface side. . In the attracting magnet 170, a magnetic back yoke 172 is attached to a surface (back surface) opposite to the surface facing the inner bottom surface 115 of the housing 110. The attracting magnet 170 prevents the rotor shaft 140 from coming off the dynamic pressure bearing portion 150 together with the stopper 180 even when the dynamic pressure bearing motor 100 is turned upside down.

  A stator 120 is fitted on the outer periphery of the housing 110 at a predetermined interval above the substrate.

  In the stator 120, salient poles (also referred to as magnetic poles or slots) 122 project from the outer peripheral surface of a cylindrical stator core 121 fitted on the housing 110 in a radial direction at a predetermined interval. The coil part 123 is wound. In the stator core 121, the portions other than the salient poles 122 are covered with a core cover 124 made of an insulating resin. A lead bar 125 connected to the substrate at one end is attached to the core cover 124, and the magnet wire of the coil portion 123 is entangled with the other end of the lead rod 125, so that the wiring of the substrate and the coil portion 123 is electrically connected.

  An annular rotor magnet 133 that rotates around the stator 120 in the circumferential direction is arranged at a predetermined interval on the outer side in the radial direction of the coil portion 123.

  Here, the rotor magnet 133 has a cylindrical shape arranged so as to surround the periphery of the stator 120, and is held by the rotor yoke 134 from the outer peripheral side.

  The rotor yoke 134 is provided with a flat plate-shaped upper surface portion 134b protruding in the axial direction from one (upper) opening edge portion of the cylindrical peripheral wall portion 134a. The inner peripheral surface and the upper surface portion of the peripheral wall portion 134a. A rotor magnet 133 is attached to the inner surface of the. That is, the rotor yoke 134 is formed in a cup shape having an opening at the center portion of the bottom portion (corresponding to the upper surface portion 134b) and covering the stator 120 from the opening side.

  The rotor yoke 134 is fixed in a cup-shaped impeller body 132a provided so as to cover from the outside. The rotor yoke 134 is fixed by being partially press-fitted into the impeller body 132a via a rib 132b protruding from the inner peripheral surface of the impeller body 132a.

  In the cup-shaped impeller body 132a, a hub 136 is formed at the center of the bottom surface 132c, and the rotor shaft 140 is attached through the hub 136 so as to be orthogonal to the bottom surface 132c of the impeller body 132a.

  The rotor shaft 140 is integrally attached to the hub 136 of the impeller 132 by insert molding on the base end portion 140a side, and is inserted from an opening on one end side (upper side) of the hydrodynamic bearing portion 150 fitted in the housing 110. Yes.

  In the rotor shaft 140, a stopper mounting groove 144 extending in the circumferential direction is formed at the tip 142 protruding from the other end of the hydrodynamic bearing 150. The stopper mounting groove 144 is attached with a substantially disk-shaped stopper 180 that protrudes outward in the radial direction and is disposed to face the lower surface of the other end side (lower side) of the dynamic pressure bearing portion 150.

  When the rotor shaft 140 moves in a direction (upward) from which the rotor shaft 140 is removed from the dynamic pressure bearing portion 150, the stopper 180 is hooked on the lower surface portion of the dynamic pressure bearing portion 150 so that the rotor shaft 140 is removed in the removal direction. To prevent.

  FIG. 2 is a perspective view of a stopper in the hydrodynamic bearing motor according to the present invention.

  The stopper 180 protrudes in the axial direction from the inner periphery of the stopper main body 182 and the stopper main body 182 formed in a flat plate ring shape, and is disposed in the stopper mounting groove 144 (see FIG. 1) at the tip of the rotor shaft 140. And an inner ring portion 184.

  The inner peripheral ring portion 184 is formed to be thinner than the stopper main body portion 182, and at least the surface on the base end portion 140 a (see FIG. 1) side of the rotor shaft 140, in other words, the bottom surface of the hydrodynamic bearing portion 150. The surface 184 a on the side facing the (lower surface portion) 152 is farther from the bottom surface (lower surface portion 152) of the dynamic pressure bearing portion 150 than the surface 182 a of the stopper main body portion 182.

  In the stopper 180, a notch 186 is formed at a predetermined interval in the inner peripheral edge 182 b including the inner peripheral ring part 184.

  The inner circumferential ring portion 184 extending in the circumferential direction is divided by the notch portion 186. As a result, when the stopper 180 is attached to the rotor shaft 140, the inner peripheral ring portion 184 is deformed by inserting the rotor shaft 140 into the central opening of the inner peripheral ring portion 184 from the distal end side, so that the stopper mounting groove portion. It fits to 144.

  Further, the thickness of the inner peripheral ring portion 184 of the stopper 180 is shorter than the groove width in the stopper mounting groove portion 144 (the axial length of the bottom surface of the groove 114). Thereby, the stopper 180 is attached in a state of loosely fitting in the stopper attachment groove 144, and even if the rotor shaft 140 rotates, the rotational force is not hindered. In the dynamic pressure bearing motor 100, the rotor shaft 140 is attracted to the inner bottom surface 115 side of the housing 110 by the attracting magnet 170, so that the stopper 180 may be removed from the rotor shaft 140.

  FIG. 3 is a side sectional view for explaining a dynamic pressure bearing portion in the dynamic pressure bearing type motor according to the present invention.

  As shown in FIG. 3, the hydrodynamic bearing portion 150 is formed in a cylindrical shape from a sintered metal such as a sintered metal mainly composed of copper. The hydrodynamic bearing unit 150 may be formed in a cylindrical shape by a porous body of oil-impregnated sintered metal impregnated with lubricating oil or lubricating grease.

  A herringbone-shaped dynamic pressure groove portion (herringbone groove portion) 154 as a dynamic pressure generating groove is formed on the inner peripheral surface 153 which is a bearing surface of the dynamic pressure bearing portion 150 at both opening side end portions.

  The herringbone groove portion 154 is formed at both opening side end portions of the inner peripheral surface by a herringbone groove forming portion 155 (indicated by hatching in the figure) that protrudes axially from the inner peripheral surface.

  The herringbone groove forming portion 155 includes a belt-like region 155a arranged in the circumferential direction and one end in the axial direction at the same inner surface level as the inner surface of the belt-like region 155a from the circumferential edges extending in the circumferential direction in the belt-like region. And a plurality of bone portions 155b provided at predetermined intervals so as to extend in an inclined manner.

  The herringbone groove portion 154 formed between the bone portions 155b can increase the amount of lubricating oil in the dynamic pressure bearing portion 150, and can increase the accuracy of the rotor shaft 140 by generating dynamic pressure by a pumping action. I support it well.

  In addition, an outer groove 156 a formed along the axial direction and connected to the outer edge portions of the upper surface portion 157 and the lower surface portion 152 is formed on the outer peripheral surface 156 of the dynamic pressure bearing portion 150. Note that a plurality of outer grooves 156a are formed on the outer peripheral surface 156 at symmetrical positions about the axis here.

  In the dynamic pressure bearing portion 150, an air flow path is formed in the inner peripheral surface 153, the outer peripheral surface 156, the lower surface portion 152, and the upper surface portion 157 in a state of being disposed in the housing 110. Specifically, as shown in the figure, in each of the annular upper surface portion 157 and the lower surface portion 152, annular inner edge flow paths 152a and 157a and outer edge flow paths 152b formed by C-surface processing on the inner peripheral edge and the outer peripheral edge, 157b is formed. Each outer edge channel 152b, 157b communicates with the outer groove 156a.

  4 is a bottom view of the hydrodynamic bearing portion, and FIG. 5 is a top view of the hydrodynamic bearing portion.

  As shown in FIG. 4, a communication flow path 152 c that communicates between the inner edge flow path 152 a and the outer edge flow path 152 b is formed on the lower surface portion 152 of the dynamic pressure bearing portion 150.

  As shown in FIG. 5, a communication flow path 157 c that communicates between the inner edge flow path 157 a and the outer edge flow path 157 b is formed on the upper surface portion 157 of the dynamic pressure bearing portion 150. Further, a central portion between the outer edge flow path 157b and the inner edge flow path 157a is notched around the axis in the upper surface portion 157, and an annular groove portion 157d extending in the circumferential direction and communicating with the communication flow path 157c is formed. Yes.

  As described above, in the dynamic pressure bearing portion 150, the air flow path connecting the inner peripheral surface 153 and the outer peripheral surface 156 is formed in each of the lower surface portion 152 and the upper surface portion 157, and the lower surface portion 152 and the upper surface portion 156 are formed by the outer groove 156a. The flow path of the upper surface part 157 is also connected to the outer peripheral surface 156.

  As a result, in the dynamic pressure bearing portion 150, air and lubricating oil flow paths that connect the lower surface portion 152, the outer peripheral surface 156, the inner peripheral surface 153, and the upper surface portion 157 are formed even when fitted in the housing 110. .

  A cap 190 that is fitted into the housing 110 by light press fitting is put on the upper end portion including the upper surface portion 157 in the dynamic pressure bearing portion 150. The hydrodynamic bearing unit 150 is fixed to the housing 110 by a cap 190, an adhesive layer 200 that fixes the cap 190 to the housing 110, and light press-fitting into the housing 110. The hydrodynamic bearing unit 150 is fixed in a state in which movement in the thrust direction is restricted by the cap 190.

  6 to 8 are diagrams for use in the configuration of the cap in the hydrodynamic bearing motor according to the present invention. FIG. 6 is a top view of the cap, FIG. 7 is a bottom view of the cap, and FIG. FIG.

  The cap 190 is disposed on the upper surface portion 157 of the hydrodynamic bearing portion 150, and has a disc-shaped lid upper surface portion 192 through which the rotor shaft 140 is rotatably inserted into the central opening 190 a, and an outer peripheral edge of the lid upper surface portion 192. And a cylindrical wall portion 194 that covers the outer peripheral surface of the upper end portion of the hydrodynamic bearing portion 150.

  In the cap 190, the corner of the lower end surface of the cylindrical wall portion 194, the outer peripheral edge of the lid, and the inner peripheral edge forming the edge of the opening are C-surface processed.

  As shown in FIGS. 7 and 8, a rib 195 is formed on the back surface 192 a of the lid upper surface portion 192 so as to protrude downward and be disposed along the inner peripheral surface 194 a of the cylindrical wall portion 194. The lid upper surface portion 192 of the cap 190 that covers the dynamic pressure bearing portion 150 by the rib 195 is disposed on the upper surface portion 157 of the dynamic pressure bearing portion 150 in a state of being separated via the rib 195, as shown in FIG. An air reservoir 196 is formed between the back surface 192 a of the lid upper surface 192 and the upper surface 157 of the hydrodynamic bearing unit 150.

  In addition, a notch 197 is formed at a predetermined interval on the outer peripheral edge of the upper surface of the lid upper surface 192.

  The cap 190 formed in this manner is fitted into the bearing housing portion 112, and protrudes into the cap housing portion 113. The upper end portion of the hydrodynamic bearing portion 150 (the dynamic pressure located in the cap housing portion 113 of the housing 110). The outer peripheral surface 156 and the upper surface portion 157) of the bearing portion 150 are attached so as to cover.

  In other words, the cap 190 is formed between the inner peripheral portion of the housing 110 that forms the cap accommodating portion 113 of the housing 110 and the upper end portion of the hydrodynamic bearing portion 150 that projects from below into the cap accommodating portion 113. The cylindrical wall portion 194 is interposed between the upper end portion of the hydrodynamic bearing portion 150 by light press-fitting.

  The cap 190 is also attached to the housing 110 by light press fitting. Specifically, the outer peripheral surface of the cap 190, that is, the outer peripheral surface of the cylindrical wall portion 194 is pressed against the inner peripheral surface of the cap housing portion 113 formed corresponding to the outer diameter of the cylindrical wall portion 194. Are in contact with each other. Further, the upper surface of the cap 190 (the upper surface of the lid) is at a lower height than the upper end of the housing 110.

  The cap 190 is fixed to the housing 110 by an adhesive layer 200 formed on the outer peripheral edge portion of the lid upper surface portion 192.

  The adhesive layer 200 is formed in a gap (adhesive layer forming portion) between the outer surface of the cap 190 attached to the housing 110 together with the dynamic pressure bearing portion 150 and the upper end portion of the inner peripheral surface of the housing 110, for example, UV-based heat. It is formed by filling with an adhesive that hardens. Note that the adhesive layer forming portion 114 communicates with the cap housing portion 113 of the housing 110 in the upper part, and a portion that is recessed with respect to the axial center from the inner peripheral surface surrounding the cap housing portion 113 and an upper end opening portion of the housing 110. It is formed by the C surface formed in the inner side opening edge. As described above, the adhesive layer 200 includes a C surface portion of the inner peripheral edge of the upper end portion of the housing 110 and an inner peripheral surface that defines the adhesive layer forming portion 114 and an outer surface of the cap 190 protruding into the adhesive layer forming portion 114. Formed in between.

  Further, since the notch portion 197 is formed in the lid upper surface portion 192 of the cap 190, the adhesive serving as the adhesive layer 200 formed along the outer edge of the lid upper surface portion 192 is filled. Thereby, the adhesive filled in the notch 197 has a function of a claw for fixing the cap 190, and the adhesive layer 200 is disposed on the outer side of the cap 190 and the cap 190 in the radial direction. The cap 190 and the hydrodynamic bearing 150 are firmly fixed to the housing 110 while sealing the space between the housing 110 and the housing 110.

  Further, the upper surface of the lid upper surface portion 192 of the cap 190 is lower in height than the upper end portion of the housing 110. For this reason, when the adhesive is filled along the inner periphery of the upper end portion of the housing 110, the adhesive flows to the outer peripheral edge portion of the lid portion of the cap 190, so that the adhesive region is enlarged.

  The air reservoir 196 in the cap 190 formed by covering the dynamic pressure bearing portion 150 in the housing 110 has an inner edge channel 157a, an outer edge channel 157b, and a communication channel 157c in the upper surface portion 157 of the dynamic pressure bearing portion 150. And the annular groove 157d. The outer edge channel 157b communicates with the outer groove 156a. Therefore, the air reservoir portion 196 communicates with the air paths A1 to A3 (see FIGS. 3 to 5) formed in the dynamic pressure bearing portion 150.

  In the housing 110 that fixes and holds the dynamic pressure bearing portion 150 in which the rotor shaft 140 is inserted as described above, oil is filled up to the upper surface portion 157 of the dynamic pressure bearing portion 150.

  Here, an assembling method of the hydrodynamic bearing type motor 100 will be described.

  In the hydrodynamic bearing type motor 100, the shaft receiving washer 116 is disposed on the bottom surface in the housing 110, and the stopper 180 is disposed on the bottom surface portion of the bearing housing portion 112 with the center portion of the stopper 180 aligned with the axis. The hydrodynamic bearing portion 150 is inserted into the bearing housing portion 112.

  At this time, the dynamic pressure bearing portion 150 is attached to the housing 110 in a light press-fitted state, that is, a state in which a portion surrounding the bearing housing portion 112 is pressed on the inner peripheral surface of the housing 110.

  Then, a predetermined amount of oil is filled in the dynamic pressure bearing portion 150, and the cap 190 is placed on the upper end portion including the upper surface portion 157 of the dynamic pressure bearing portion 150 attached in the housing 110. At this time, the cap 190 is in a state where the inner peripheral surface of the cylindrical wall portion 194 presses against the outer peripheral surface of the upper surface portion 157 of the housing 110, and the cap 190 is attached to the housing 110 by light press fitting. The cap 190 is fixed to the housing 110 with the adhesive layer 200.

  In the cap 190, the cylindrical wall portion 194 is put on the outer periphery of a substantially perfect circle of the dynamic pressure bearing portion 150. The cylindrical wall portion 194 has a disc-shaped lid upper surface portion in which a circular opening through which the rotor shaft 140 is inserted is formed at the center so as to close one (upper) opening of the cylindrical wall portion 194. 192 is provided. For this reason, the opening 190a of the lid upper surface portion 192 can be positioned on the same axis center corresponding to the circular opening of the dynamic pressure bearing portion 150 only by being attached to the dynamic pressure bearing portion 150.

  Accordingly, even if the cap 190 is attached to the upper end portion of the dynamic pressure bearing portion 150, the cap 190 is arranged so that the rotor shaft 140 inserted into the dynamic pressure bearing portion 150 is positioned on the correct axis C. Can be inserted into the hydrodynamic bearing 150 from above.

  Then, the inserted rotor shaft 140 is engaged with the stopper 180 in the housing 110 at the tip thereof.

  As described above, when the rotor shaft 140 is inserted into the dynamic pressure bearing portion 150 and the cap 190 fixed in a state where oil is filled therein, the air in the dynamic pressure bearing portion 150 is pushed downward.

  The flow of air when the rotor shaft 140 moves to the front end side in the thrust direction in the hydrodynamic bearing 150 will be described with reference to FIG. 1 and air paths A1 to A3 in FIGS.

  When the rotor shaft 140 is inserted and attached from the upper surface side by filling the inside of the dynamic pressure bearing portion 150 with oil, the air existing on the bottom surface side of the dynamic pressure bearing portion 150 is inserted from the inserted rotor shaft 140. It is pressed in the direction (bottom direction of the housing 110). The pressed air passes through the inner edge channel 152a of the lower surface portion 152, the communication channel 152c, and the outer edge channel 152b, passes through the outer groove 156a of the outer surface 156 of the hydrodynamic bearing unit 150, and escapes to the upper surface portion 157 side. The air that has escaped to the upper surface portion 157 escapes upward on the upper surface portion 157 by the outer edge channel 157b, the communication channel 157c, the annular groove 157d, and the inner edge channel 157a.

  The air that has escaped upward passes through the air reservoir 196 inside the cap 190, and escapes upward from between the peripheral surface forming the opening 190 a of the lid upper surface 192 of the cap 190 and the outer surface of the rotor shaft 140. Note that an oil repellent is applied to the outer surface portion of the rotor shaft 140 facing the peripheral surface forming the opening 190 a of the cap 190.

  The air reservoir 196 serves as a buffer for air escape, and even when the rotor shaft 140 moves in the thrust direction with respect to the dynamic pressure bearing portion 150, such as when the rotor shaft 140 is inserted into the dynamic pressure bearing portion 150, the dynamic pressure type. The lubricating oil in the hydrodynamic bearing portion 150 does not jump out above the hydrodynamic bearing portion 150.

  The bearing device included in the dynamic pressure bearing motor 100 configured as described above has a resin housing 110 having an opening at one end and a cylindrical inner peripheral surface, and is fitted into the housing 110 through the opening. At least one of the dynamic pressure bearing portion 150, the rotor shaft 140 that is rotatably inserted into the dynamic pressure bearing portion 150, and the outer peripheral surface of the rotor shaft 140 that faces the inner peripheral surface of the dynamic pressure bearing portion 150. The herringbone groove 154 formed, the dynamic pressure generating lubricant held between the inner peripheral surface of the dynamic pressure bearing portion 150 and the outer peripheral surface of the rotor shaft 140, and the rotor shaft 140 are rotatably inserted. And fixed to the opening side of the housing 110 and attached to the upper end portion opposite to the fitting direction of the dynamic pressure bearing portion 150 so as to cover the upper end portion, and the thrust direction of the dynamic pressure bearing portion 150 And a cap 190 for restricting the movement of the. The cap 190 has a lid upper surface portion 192 through which the rotor shaft 140 is inserted and closes the opening of the housing 110, and a cylindrical shape that hangs down from the outer peripheral edge of the lid upper surface portion 192. A cylindrical wall portion 194 is fitted on the outer peripheral surface of the upper end portion of the bearing portion 150 by press fitting, and is fitted on the inner peripheral surface of the opening of the housing 110 on the outer peripheral surface.

  That is, in the hydrodynamic bearing motor 100, the hydrodynamic bearing portion 150 that is fitted into the resin housing 110 and receives the rotor shaft 140 is fixed to the housing 110 via the cap 190 that covers the upper end portion. In addition to the pressure input to the housing 110, the cap 190 is designed to improve the strength of fixing to the hydrodynamic bearing portion 150 by the adhesive layer 200 that adheres to the housing 110.

  For this reason, in the hydrodynamic bearing motor 100, the resin housing 110 that holds the hydrodynamic bearing portion 150 on the outside is deformed by the bearing temperature of the hydrodynamic bearing portion 150 due to the rotation of the rotor shaft 140 when the motor is driven. Even in the case where there is a gap between the outer peripheral surface 156 of the dynamic pressure bearing portion 150, the movement of the dynamic pressure bearing portion 150 in the thrust direction is restricted by the cap 190 fixed to the housing 110. Thus, the housing 110 can hold the dynamic pressure bearing portion 150 through the cap 190 without moving it in the thrust direction.

  Therefore, even if the cylindrical housing 110 into which the hydrodynamic bearing portion 150 is inserted is formed of a resin cylindrical body instead of a conventional metal cylindrical body such as brass, the bearing temperature (temperature range when the motor is used) ), The hydrodynamic bearing 150 can be stably fixed.

  Moreover, since the opening part of the housing 110 is obstruct | occluded with the cap 190 which has the air reservoir part 196, lubricating oil does not leak outside, but durability and reliability of the dynamic pressure bearing motor 100 itself can be ensured.

  In the present embodiment, when inserting and fixing the dynamic pressure bearing portion 150 in the resin housing 110, unlike the conventional case, a temperature range during use of the motor (a use temperature range that can withstand the bearing temperature) is assumed. It is not necessary to increase and fix the pressure input of the dynamic pressure bearing portion 150 to the housing 110, and the dynamic pressure bearing portion 150 is not deformed by a high pressure input. That is, it can be fixed to the housing 110 of the dynamic pressure bearing portion 150 without changing the inner diameter dimension of the dynamic pressure bearing portion 150 by the pressure from the outer peripheral surface side. Therefore, the dynamic pressure bearing motor 100 can be assembled without considering the heat resistant temperature range (the range that can withstand the bearing temperature) when the motor is used in the housing 110.

  As described above, in the hydrodynamic bearing motor 100 of the present embodiment, in the structure in which the cost is reduced by using the resin housing 110, the temperature of the housing 110 increases due to the bearing temperature when the rotor 130 rotates ( The dynamic pressure bearing portion 150 can be fixed with high accuracy and stable strength without considering the heat resistant temperature range when the motor is used.

  Further, the hydrodynamic motor can be assembled while maintaining the accuracy of the hydrodynamic bearing unit 150 alone.

  Further, in the housing 110, the stopper mounting groove 144 formed at the tip end portion 142 of the rotor shaft 140 projects outward in the radial direction and faces the lower surface portion on the other end side (lower side) of the dynamic pressure bearing portion 150. A substantially circular disc-shaped stopper 180 is attached.

  As a result, the rotor shaft 140 itself is restricted from moving in the thrust direction in response to an impact in the thrust direction. Therefore, when an impact or vibration is applied during transportation or the like, the pumping operation due to the shaft moving in the thrust direction is unlikely to occur, and leakage of the lubricating oil from the housing 110 can be prevented.

  The embodiment of the present invention has been described above. The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

  The hydrodynamic bearing type motor according to the present invention can reduce the cost and has the effect of holding the hydrodynamic bearing portion with high accuracy and stable strength without considering the bearing temperature when the motor is used. It is useful as an exhaust fan motor, spindle motor, and polygon scanner motor.

Sectional drawing which shows the principal part which shows the structure of the hydrodynamic bearing type motor which concerns on one embodiment of this invention. The perspective view of the stopper in the fluid dynamic bearing type motor concerning the present invention Side sectional view explaining a hydrodynamic bearing portion in a hydrodynamic bearing type motor according to the present invention The bottom view of the hydrodynamic bearing part in the hydrodynamic bearing type motor which concerns on this invention The top view of the fluid dynamic bearing part in the fluid dynamic bearing type motor concerning the present invention The figure which uses for the structure of the cap in the fluid dynamic bearing type motor which concerns on this invention The figure which uses for the structure of the cap in the fluid dynamic bearing type motor which concerns on this invention The figure which uses for the structure of the cap in the fluid dynamic bearing type motor which concerns on this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Dynamic pressure bearing type motor 110 Housing 140 Rotor shaft 150 Dynamic pressure bearing part 154 Herringbone groove part 190 Cap

Claims (3)

A resin housing having an opening at one end;
A bearing portion having a cylindrical inner peripheral surface and fitted into the housing from the opening;
A rotor shaft rotatably inserted into the bearing portion;
A dynamic pressure generating groove formed on at least one of the inner peripheral surface of the bearing portion and the outer peripheral surface of the rotor shaft facing the inner peripheral surface;
A dynamic pressure generating lubricating oil held between the inner peripheral surface of the bearing and the outer peripheral surface of the rotor shaft;
A rotor shaft is rotatably inserted, is fixed to the opening side of the housing, and is attached to an upper end portion opposite to the fitting direction of the bearing portion so as to cover the upper end portion. And a cap that restricts movement in the thrust direction,
The cap has a lid upper surface portion through which the rotor shaft is inserted and closes the opening;
It forms a cylinder that hangs down from the outer peripheral edge of the upper surface of the lid, and is fitted on the outer peripheral surface of the upper end portion of the bearing portion by press-fitting at the inner peripheral surface, and at the outer peripheral surface, the inner periphery of the opening A cylindrical wall part fitted in the surface;
A hydrodynamic bearing motor.   A part of the inner peripheral surface of the cylindrical wall portion of the cap is provided so as to protrude in the axial direction, and when attached to the upper end portion, the lid upper surface portion and the bearing portion are separated from each other. The hydrodynamic bearing motor according to claim 1, wherein a rib to be formed is formed. The upper surface of the cap is disposed at a position lower than the opening edge of the housing,
2. The hydrodynamic bearing according to claim 1, wherein an adhesive layer is provided between the outer peripheral edge of the upper surface of the cap and the opening edge and is filled with an adhesive across the outer peripheral edge and the opening edge. Motor.

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