JP2007046694A - Bearing unit and rotary device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing unit which does not easily isolate a rotary shaft from a thrust bearing even if any external force is added on the bearing unit while an ejection outside is feasible even if air bubbles are swollen by a residual air or the like. <P>SOLUTION: The bearing unit 30A is provided with a radial bearing 33A to support freely rotatably the rotary shaft 31, the thrust bearing 46 to support the rotary shaft 31 in the axial direction and to be formed in the inner part bottom surface, a passage forming member 34A which is also a thrust shaft member, a communication passage 50 provided in the outer periphery of the radial bearing 33A to link both ends of the radial bearing 33A, a housing 60 provided with functions to hold the radial bearing 33A, the passage forming member 34A, the passage forming member lid body 40A, while leaving a shallow air gap in only one end of the rotary shaft 31 for release and covering surroundings of the radial bearing 33A, a lubricant oil L filling the housing 60 including the air gap, and a non-return preventing mechanism 70 formed in the communication passage 50. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a highly reliable bearing unit capable of preventing leakage of lubricating oil almost completely and preventing floating and dropping of a rotating shaft, and a rotating device such as a motor using the bearing unit.

  First, a conventional bearing unit will be described with reference to FIGS. 9 to 11.

  FIG. 9 is a sectional side view of a bearing unit according to the first embodiment of the prior art, FIG. 10 is a sectional perspective view showing an example of a dynamic pressure generating groove formed on the inner peripheral surface of the radial bearing shown in FIG. 9 is a cross-sectional side view of the bearing unit when an undesirable state occurs in the bearing unit shown in FIG. 9, FIG. 12 is a cross-sectional side view of the bearing unit of the second form of the prior art, and FIG. 13 is a passage shown in FIG. FIG. 14 is a perspective view showing the shape of the communication passage formed between the forming member lid and the radial bearing. FIG. 14 shows the passage forming member shown in FIGS. Fig. B is a top view thereof, Fig. C is a cross-sectional view taken along the line C-C of Fig. B, and Fig. 15 is a view of the bearing unit when an undesirable state occurs in the bearing unit shown in Fig. 12. It is a cross-sectional side view.

  First, the configuration and structure of the bearing unit 30B according to the first embodiment of the prior art will be described with reference to FIG.

  The bearing unit 30B is configured as shown in FIG. 24 of [Patent Document 1], and rotatably supports the rotating shaft 31, and supports the rotating shaft 31 in the direction around the outer periphery. A radial bearing 33 and a housing 60 that houses the radial bearing 33 are provided.

  In this bearing unit 30B, the radial bearing 33 constitutes a hydrodynamic bearing together with the lubricating oil L which is a viscous fluid filled in the housing 60. As shown in FIG. 9 and FIG. Dynamic pressure generating grooves 43 and 44 for generating dynamic pressure are formed on the inner peripheral surface of the rotary shaft insertion hole 33h through which 31 is inserted.

  As shown in FIG. 9, the housing 60 that houses the radial bearing 33 that supports the rotating shaft 31 surrounds the radial bearing 33 except for the rotating shaft insertion hole 33 h of the cylindrical radial bearing 33. It is one member integrally molded with a synthetic resin.

  That is, the structure of the housing 60 is such that a thrust bearing 46 is formed except for a portion of the housing main body 61 that surrounds the outer periphery of the cylindrical radial bearing 33, and the rotation shaft insertion hole 33h of the radial bearing 33. Except for the bottom closing part 62 formed integrally and the shaft insertion hole 40h of the radial bearing 33, the rotating part releasing side end face 33a side is covered, and the upper closing part 63 is formed integrally with the housing body 61. The housing 60 thus configured has a structure in which the radial bearing 33 is arranged on the inner peripheral side of the housing body 61 by outsert molding of a synthetic resin material so as to surround the cylindrical radial bearing 33. It can be formed integrally.

  A shaft insertion hole 64 through which the rotation shaft 31 rotatably supported by the radial bearing 33 is inserted is provided at the center of the upper closing portion 63 of the housing 60. A thrust bearing 46 that rotatably supports a lower end portion 31 b that is one end portion in the thrust direction of the rotating shaft 31 supported by the radial bearing 33 is integrally formed at the center portion on the inner surface side of the bottom closing portion 62. At the same time, this portion is also a lubricating oil reservoir portion D.

  The thrust bearing 46 is formed as a pivot bearing that supports the lower end portion 31b of the rotating shaft 31 formed in an arc shape or a tapered tip shape with a point.

  By the way, the shaft insertion hole 64 has an inner diameter slightly larger than the outer shape of the rotation shaft main body 31a so that the rotation shaft 31 inserted through the shaft insertion hole 64 rotates without slidingly contacting the inner peripheral surface of the shaft insertion hole 64. Is formed. At this time, the shaft insertion hole 64 has a gap 65 between the peripheral surface and the outer peripheral surface of the shaft portion main body with a gap c sufficient to prevent the lubricating oil L filled in the housing from leaking from the inside of the housing 60. Formed as follows.

  A tapered portion 31 c is provided on the outer peripheral surface facing the inner peripheral surface of the shaft insertion hole 64 of the rotation shaft 31. The tapered portion 31 c is inclined so as to expand a gap 65 formed between the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the shaft insertion hole 64 toward the outside of the housing 60. The taper portion 31 c forms a pressure gradient in the gap 65 formed between the outer peripheral surface of the rotating shaft 31 and the inner peripheral surface of the shaft insertion hole 64, and the lubricating oil L filled in the housing 60 is supplied to the housing 60. Generates a force that pulls in Accordingly, since the lubricating oil L is drawn into the housing 60 when the rotary shaft 31 rotates, the lubricating oil L is placed in the dynamic pressure generating grooves 43 and 44 of the radial bearing 33 that is configured as a dynamic pressure fluid bearing. It is possible to reliably enter and generate dynamic pressure, to support the rotating shaft 31 in a stable state, and to prevent the lubricating oil L filled in the housing 60 from leaking.

  In the bearing unit 30 </ b> B configured as shown in FIG. 9, the rotation shaft 31 is exposed only at one end on the shaft insertion hole 64 side, and the housing member is seamlessly covered except for a slight gap in the shaft insertion hole 64. . Therefore, the bearing unit 30B can prevent the lubricating oil L from leaking to the outside of the housing 60. Further, since the communication portion with the outside is only the gap of the shaft insertion hole 64, the scattering of the lubricating oil L due to an impact can be prevented.

  However, in the bearing unit 30B, as shown in FIG. 11, when the rotating shaft 31 rotates with respect to the radial bearing 33 to generate dynamic pressure, the static pressure inside the bearing unit 30B is extremely reduced. When the pressure inside the housing 60 decreases, the air slightly remaining inside the housing 60 or the air dissolved in the viscous fluid such as the lubricating oil L expands. As the air inside the housing 60 and the air dissolved in the lubricating oil L expand, the air pressure around the lubricating oil reservoir D rises above the pressure around the rotating shaft insertion hole 64 side of the housing 60 and rotates. The shaft 31 is pushed up from the thrust bearing 46, and the lubricating oil L is also pushed up.

  Then, the lubricating oil L leaks from the shaft insertion hole 64, and the lubricating oil surface in the tapered portion 31c (seal portion) is eventually lowered, and finally air enters the bearing unit 30B.

  As described above, in the bearing unit 30B shown in FIG. 9, due to the generation of the dynamic pressure caused by the rotation shaft 31 and its rotation, the internal air expands, the lubricating oil L leaks, and the rotation shaft 31 floats from the thrust bearing 46. There is a problem of end.

  A bearing unit that solves this problem is the bearing unit 30C of the second form of the prior art shown in FIG. 12, and this bearing unit 30C is the bearing unit of the invention disclosed in FIG. 3 of [Patent Document 1]. is there.

  Hereinafter, the configuration and structure of the bearing unit 30C will be described with reference to FIG. 12. In the bearing unit 30C, portions common to the bearing unit 30B are denoted by the same reference numerals and detailed description will be made. Omitted.

  In this bearing unit 30C, a dynamic pressure generating groove 32 is formed vertically at a predetermined interval on the outer periphery of a rotary shaft main body 31a that is mainly supported by a dynamic pressure bearing of the rotary shaft 31. A radial bearing 33 in which a rotary shaft release side end surface 33a and a thrust bearing side end surface 33b are formed, a passage forming member 34 that covers a part of the outer peripheral surface of the radial bearing 33, and the rotary shaft 31 is inserted in the center. A shaft insertion hole 40h having a diameter that can be formed is formed, and a passage forming member lid body 40 that covers the rotary shaft release side end surface 33a of the radial bearing 33, and the radial bearing 33, the passage formation member 34, and the passage except for the shaft insertion hole 40h. The housing 60 etc. which cover | cover and hold | maintain the whole formation member cover body 40 integrally are comprised.

  As shown in FIG. 13, the radial bearing 33 has a cylindrical structure, and has a rotation shaft insertion hole 33 h formed in the center. The upper end surface is a rotation shaft release side end surface 33 a and the lower end surface is It is formed as a thrust bearing side end surface 33b, and at least one, in this embodiment, three first grooves 51 are formed on the outer peripheral surface thereof, and at least one of the thrust bearing side end surface 33b is provided on the thrust bearing side end surface 33b. In the embodiment, three second grooves 52 are formed, and in the present embodiment, at least one third groove 53 is formed on the rotary shaft release side end surface 33a, and each of the third grooves 53 is formed. The second groove 52 and the third groove 53 communicate with each other above and below one groove 51 to form three communication passages 50.

  The passage forming member (or may be referred to as a thrust bearing member, but is collectively described as “passage forming member” in this specification) 34 is a cup-shaped member as shown in FIGS. 12, 13, and 14. However, a thrust bearing 46 is formed on the inner surface of the bottom portion, and an upper cylindrical portion is divided by a notch 35 to secure a gap in the first groove 51 of the radial bearing 33. Three arc-shaped plates 36 that cover the groove 51 are formed, and a space 37 that can accommodate a flexible retaining washer 49 that can be expanded by inserting the rotating shaft 31 into the center portion and the rotating shaft at the bottom. A thrust space S (FIG. 12) is formed that includes a space 38 that can accommodate the lower end portion 31 b of 31. These spaces 37 and 38 also communicate with the second groove 52 constituting the communication passage 50, and are spaces where the lubricating oil L can circulate. Further, an engaging claw 39 is formed inward at the periphery of the upper opening.

  As shown in FIG. 13, the passage forming member lid 40 has a donut-shaped flat disk shape, and a shaft insertion hole 40h is formed at the center. The passage forming member lid 40 is slightly larger than the diameter of the engaging claw 39 formed in the opening of the passage forming member 34, and the engaging claw 39 is pushed and expanded so as not to come out upward. Stopped.

  In order to assemble the bearing unit 30, firstly, a retaining washer 49 is disposed in advance in the space 37 of the passage forming member 34, and the radial bearing 33 is fitted therein with the thrust bearing side end face 33 b side down, The passage forming member lid 40 is fitted from above the passage forming member 34 and fixed by the engaging claws 39 so as to be in close contact with the rotary shaft release side end surface 33a of the radial bearing 33.

  By assembling in this way, a tubular space passage is formed by closing the three third grooves 53 of the radial bearing 33 with the passage forming member lid body 40, and the three first grooves 51 of the radial bearing 33 are formed. Is closed by the arc-shaped plate 36 of the passage forming member 34 to form a tubular space passage, and the three second grooves 52 of the radial bearing 33 are released to the thrust space S (spaces 37 and 38), Lubricating oil L can be supplied to and circulated through the dynamic pressure generating groove 32 of the rotary shaft 31 through the communication passage 50 including these spatial passages, and the rotary shaft 31 is supported by the radial bearing 33 and the thrust bearing 46 to rotate. It serves to short-circuit the pressure that is generated.

  When the mold is used in this assembled state and the resin is sealed from the outer surface of the passage forming member 34 to the upper surface of the passage forming member lid 40 excluding the rotation shaft insertion hole 40h, the die is exposed by the notch 35 of the passage forming member 34. It can be covered with a resin housing 60 over a part of the outer peripheral surface of the radial bearing 33 and the outer surface of the circular arc plate 36 and over the upper surface of the passage forming member lid 40.

  After that, if the rotary shaft 31 is inserted and pushed into the center portion of the shaft insertion hole 64 of the housing 60, the rotation shaft insertion hole 40h of the passage forming member lid 40, the rotation shaft insertion hole 33h of the radial bearing 33 and the retaining washer 49, FIG. The bearing unit 30C having the structure as shown in FIG.

  The structure of the rotary shaft 31 includes a rotary shaft main body 31a that is supported by a dynamic pressure generating bearing at a radial bearing 33 portion, a lower end portion 31b that is supported by a thrust bearing 46, and a mounting portion 31d to which, for example, a rotor of a rotating device is attached. The taper 31c is formed in an intermediate portion between the mounting portion 31d and the rotary shaft main body 31a, and is formed in a tapered shape at the upper opening portion of the shaft insertion hole 64 of the housing 60.

  Therefore, after completion of the bearing unit 30C, the lubricating oil L is injected from between the shaft insertion hole 64 of the housing 60 and the tapered portion 31c of the rotary shaft 31, and this injection rotates with the rotary shaft insertion hole 33h of the radial bearing 33. Lubricating oil L can be distributed to each communication passage 50 between the shaft 31 and the shaft 31.

  In this way, the bearing unit 30 is assembled.

  Also in the case of this bearing unit 30 </ b> C, a gap formed between the outer peripheral surface of the rotary shaft 31 and the inner peripheral surface of the shaft insertion hole 64 on the outer peripheral surface facing the inner peripheral surface of the shaft insertion hole 64 of the rotary shaft 31. Since the taper part 31c which inclines so that 65 may be expanded toward the outward of the housing 60 is provided, the outer peripheral surface and shaft insertion hole of the taper part 31c of the rotating shaft 31 are the same as the case of the bearing unit 30B. A pressure gradient is formed in the gap 65 formed between the inner peripheral surface 64 and a force for drawing the lubricating oil L filled in the housing 60 into the housing 60. Accordingly, the lubricating oil L is drawn into the housing 60 when the rotating shaft 31 rotates, so that the dynamic pressure generating grooves 43 formed on the inner peripheral surface of the radial bearing 33 and the outer peripheral surface of the rotating shaft 31, The lubricating oil L surely enters the shaft 44 to generate dynamic pressure, and the rotating shaft 31 is supported in a stable state, and the leakage of the lubricating oil L filled in the housing 60 can be prevented.

  In the illustrated bearing unit 30C, the dynamic pressure generating groove 32 is formed on the rotary shaft 31, but the dynamic pressure generating grooves 43, 44 are formed on the inner peripheral surface of the radial bearing 33 as shown in FIG. May be provided.

  As described above, since the communication unit 50 is provided in the bearing unit 30 </ b> C, the dynamic pressure generated between the two dynamic pressure generating grooves 32 as the rotating shaft 31 rotates and the static pressure generated as the dynamic pressure increases. There is a function to short circuit.

  If the dynamic pressure and the static pressure are not short-circuited between the dynamic pressure generating grooves 32 here, the static pressure is relatively high when the dynamic pressure on the non-open side of the rotating shaft 31 is lower than the dynamic pressure on the open side. A force that pushes up the rotating shaft 31 is generated. As a result, when the rotating shaft 31 is pushed up, the function as a bearing unit cannot be achieved.

  In addition, the amount of dynamic pressure generated in the dynamic pressure generating groove 32 is determined by the mechanical accuracy such as the depth of the dynamic pressure generating groove, the amount of gap with the shaft, and the groove angle. Since this is impossible, it is necessary to provide a communication passage 50 between the dynamic pressure generating grooves 32 to short-circuit the dynamic pressure and the static pressure.

  Therefore, in the bearing unit 30C, since the pressure is short-circuited as described above, the phenomenon of the rotary shaft 31 being lifted does not occur unlike the bearing unit 30B.

The bearing unit as described above is suitable for use as a bearing for a motor for a heat dissipation device incorporated in an electronic device such as a computer, particularly a portable computer, but leakage of lubricating oil must be prevented as much as possible.
Japanese Patent Laying-Open No. 2005-69382 (pages 9 to 18, FIG. 3)

However, in the bearing unit 30C, unless any force for holding the rotating shaft 31 is applied, the rotating shaft 31 floats (vibrates up and down) when the bearing unit 30C receives vibration displacement from the outside in the thrust direction (axial direction). It will be. This can cause the following problems.
The bearing unit C has a structure in which the rotary shaft 31 does not fall off by the retaining washer 49. Therefore, as shown in FIG. 15, the bearing unit C is moved up and down by the space of the radial bearing 33, the retaining washer 49, and the rotational shaft 31 in the thrust direction. When the rotary shaft 31 is moved upward, the liquid level of the lubricating oil L is lowered by the volume of the rotary shaft 31 moved from the liquid level. When there is no retaining washer 49, the rotary shaft 31 will rise freely, and the liquid level of the lubricating oil L will drop by the volume of the rotary shaft 31 moved from the liquid level.

  When the liquid level of the lubricating oil L decreases, the meniscus of the lubricating oil pool (seal portion) on the inner peripheral surface of the tapered portion 31c of the rotating shaft 31 and the shaft insertion hole 64 of the housing 60 is cut off, and the air is in a bearing. Entering the inside of the unit 30C, the lubricating oil L in the gap between the radial bearing 33 and the rotary shaft 31 is cut off, which impedes the rotation performance, or the air that has entered expands due to the influence of temperature and atmospheric pressure. There is a risk of leakage to the outside of the unit 30C.

  For this reason, in a rotating device such as a motor using a bearing unit, some force may be required to press the rotating shaft 31 in the thrust direction so that the rotating shaft 31 does not float from the thrust bearing 46 (does not vibrate up and down). .

  These points are problems to be improved in the conventional bearing unit, particularly the bearing unit 30C.

  The present invention is intended to solve such problems, and can be discharged to the outside even if bubbles due to residual air expand, and the rotating shaft can be removed from the thrust bearing even if some external force is applied to the bearing unit. The object is to obtain a bearing unit that is difficult to lift.

  Therefore, in the bearing unit of the present invention, the rotation shaft insertion hole for rotatably supporting the rotation shaft is formed in the central portion, and at least one groove is formed on the outer peripheral surface connecting the rotation shaft release side end surface and the thrust bearing side end surface. A cylindrical radial bearing, a thrust bearing axially supported on the inner surface of the bottom portion, a passage forming member in which an arc-shaped plate covering at least the groove portion is formed, and the rotary shaft release of the radial bearing A passage forming member lid that covers the side end surface and has a rotation shaft insertion hole formed in the center thereof, the thrust bearing side end surface of the radial bearing facing the thrust bearing side in the passage forming member, and the outer peripheral surface In a state where the communication shaft is formed by sealing the rotary shaft release side end surface side of the radial bearing mounted so that the groove portion of the radial bearing is covered with the arc-shaped plate with the passage forming member lid, A housing formed by integrally covering the periphery of the radial bearing, the outer surface of the passage forming member, and the surface of the passage forming member lid, except for the rotation shaft insertion hole portion, and filling the housing And a backflow prevention mechanism for the lubricating oil formed on the passage forming member lid side of the communication passage.

  The backflow prevention mechanism in the bearing unit includes at least one communication passage formed on the outer peripheral surface of the radial bearing from the rotary shaft release side end surface side of the radial bearing to the thrust bearing side end surface, and the communication A space passage formed by covering the passage with the arc-shaped plate of the passage forming member, and the communication passage and the space passage from the rotary shaft release side end face side of the radial bearing to the thrust bearing side end face side. And a ball arranged to prevent the lubricating oil from flowing.

  Further, the backflow prevention mechanism in the bearing unit includes at least one communication passage formed from the rotary shaft release side end surface side to the outer peripheral surface and the thrust bearing side end surface side of the radial bearing, and the radial bearing A passage forming member lid that covers the end surface of the rotary shaft release side, a passage forming member that covers the outer periphery of the radial bearing, the communication passage, the thrust space of the thrust bearing, and the rotary shaft insertion hole of the radial bearing are filled. Formed in the lubricating oil, a semi-cylindrical sphere moving groove formed on the rotary shaft release side end face side of the communication passage, and the arc-shaped plate of the passage forming member, covering the communication passage The other semi-spheroid sphere moving groove which is combined with the semi-spheroid sphere moving groove to form the bowl-shaped sphere moving groove, and the lubricating oil passes through the communication passage from the rotary shaft release end surface side to the thrust. To prevent the flow to the receiving-side end face side, it is preferably configured with a disposed sphere in the bowl-shaped spheres moving in the groove.

  In addition, it is desirable that the depths of the two semi-cylindrical sphere movement grooves are substantially equal.

  Furthermore, it is desirable that the radial bearing is made of sintered metal.

  Furthermore, it is desirable that the radial bearing is a hydrodynamic fluid bearing in which a dynamic pressure generating groove is provided on an inner peripheral surface of the rotary shaft insertion hole.

The rotating device of the present invention is
A cylindrical radial bearing in which a rotation shaft insertion hole for rotatably supporting the rotation shaft is formed at the center, and at least one groove is formed on an outer peripheral surface connecting the rotation shaft release side end surface and the thrust bearing side end surface; A thrust bearing that supports the inner surface in the axial direction on the inner surface of the bottom portion, a passage forming member in which an arc-shaped plate covering at least the groove portion is formed, covers the rotary shaft release side end surface of the radial bearing, and a rotating shaft in the central portion A passage-forming member lid having an insertion hole, a thrust bearing side end surface of the radial bearing facing the thrust bearing side in the passage-forming member, and a groove portion of the outer peripheral surface covered with the arc-shaped plate In the state where the rotary shaft release side end face side of the radial bearing mounted in such a manner is sealed with the passage forming member lid body to form a communication passage, the rotational shaft insertion hole portion is excluded, A housing formed by integrally covering the periphery of the dial bearing, the outer surface of the passage forming member, and the surface of the passage forming member lid, lubricating oil filled in the housing, and the communication passage And a rotating shaft that is rotatably supported by the radial bearing of the bearing unit that includes the backflow prevention mechanism for the lubricating oil formed on the passage forming member lid side. It is characterized by that.

  In this case, it is desirable that the rotating shaft of the rotating device is a rotor shaft of a motor composed of a stator and a rotor.

  Therefore, according to the bearing unit of the present invention, by providing the backflow prevention mechanism, a dashpot effect is generated when the rotating shaft of the bearing unit receives a force pulled up from the housing, and the rotating shaft is moved from the thrust bearing. It can prevent being pulled apart.

  In addition, when the rotating shaft receives a (vibrational) external force that lifts from the thrust bearing, when the rotating shaft is displaced in the direction of floating from the thrust bearing, a large resistance force acts due to the dashpot effect, and the rotating shaft is In the direction of pressing against the thrust bearing, since the dashpot effect is reduced, the rotating shaft behaves so as to be pressed against the thrust bearing. For this reason, it becomes a thrust bearing strong against external force vibration.

  And, when the bearing unit of the present invention is applied to the rotating device, it is possible to obtain further stability against vibration in the thrust direction and to reduce the thrust suction force. In some cases, wear can be reduced by reducing the thrust load.

Therefore, according to the bearing unit of the present invention,
1. 1. Air can hardly enter from the outside of the bearing unit and high reliability can be obtained. Excellent effects such as being strong against external vibration when added to the bearing unit are obtained.
Moreover, according to the rotating device using the bearing unit of the present invention,
1. When a thrust suction assist mechanism is added to the rotating device to stabilize the thrust vibration, the thrust suction mechanism can be abolished, the suction force of the thrust suction mechanism can be reduced, and the cost can be reduced. 2. Since the thrust suction force can be reduced, even when the thrust bearing is a pivot bearing, excellent effects such as reduced wear and improved reliability can be obtained by reducing the thrust load.

  The bearing unit of the present invention relates to a fluid bearing, and is provided with a pressure short-circuit passage inside, and a backflow prevention mechanism is provided in the pressure short-circuit passage. With a rotating shaft.

  Hereinafter, a bearing unit of the present invention and a rotating device using the bearing unit will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a motor which is one of rotating devices according to an embodiment of the present invention, and FIG. 2 includes a backflow prevention mechanism according to an embodiment of the present invention which is used in the motor bearing shown in FIG. 3 is a cross-sectional side view of the bearing unit, FIG. 3 is a passage forming member suitable for use in the bearing unit shown in the present invention, FIG. A is an overall perspective view, FIG. B is a top view of FIG. FIG. 4C is a cross-sectional side view taken along the line CC of FIG. 4B, FIG. 4 is a perspective view of a passage forming member lid suitable for use in the bearing unit of the present invention shown in FIG. 3, and FIG. FIG. 6 is a perspective view of a radial bearing suitable for use in the bearing unit of the present invention shown in FIG. 3, and FIG. 7 is a sectional view for explaining the operation of the bearing unit of the present invention shown in FIG. 8 is a partially enlarged sectional view for explaining the operation of the backflow prevention mechanism in the bearing unit shown in FIG.

  In addition, the same code | symbol is attached | subjected and demonstrated to the same component as the conventional bearing unit 30C.

  First, referring to FIG. 1, a motor will be described as one of the rotating devices of the present invention. Here, a description will be given of a motor, particularly a motor for a heat dissipation device, that is suitable for being incorporated into an electronic device that performs arithmetic processing, recording / reproduction, and the like, and particularly a small electronic device, such as a computer, particularly a notebook computer.

  A heat dissipation device is provided inside an electronic device such as a notebook computer. The heat radiating device includes a metal base, a motor 1 attached to the base, a fan 3 rotated by the motor 1, a fan case 4 housing the fan 3, and a heat sink (not shown). ing. The configuration of the motor 1 that rotationally drives the fan 3 of the heat dissipation device will be described in detail.

  As shown in FIG. 1, the motor 1 using a bearing unit 30 </ b> A of the present invention described later includes a rotor 11 and a stator 12.

The stator 12 is integrally provided on the upper surface plate 4 a side of the fan case 4 that houses the fan 3 that is rotated by the motor 1 together with the motor 1. The stator 12 includes a stator yoke 13, a bearing unit 30A according to the present invention, a coil 14, and a core 15 around which the coil 14 is wound. The stator yoke 13 may be formed integrally with the upper surface portion 4a of the fan case 4, that is, may be formed by a part of the fan case 4, or may be formed separately. The stator yoke 13 is made of, for example, iron. The bearing unit 30 </ b> A is fixed by press-fitting or bonding into a cylindrical holder 16 formed at the center of the stator yoke 13, and further by bonding together with press-fitting.

  The holder 16 into which the bearing unit 30A is press-fitted is formed in a cylindrical shape integrally with the stator yoke 13. As shown in the figure, a core 15 around which a coil 14 to which a drive current is supplied is attached is attached to the outer periphery of a holder 16 formed integrally with the stator yoke 13.

  The rotor 11 that constitutes the motor 1 together with the stator 12 is attached to the attachment portion 31d of the rotary shaft 31 that is rotatably supported by the bearing unit 30A, and rotates integrally with the rotary shaft 31. The rotor 11 includes a rotor yoke 17 and a fan 3 including a plurality of blades 19 that rotate integrally with the rotor yoke 17. The blade 19 of the fan 3 can be formed integrally with the rotor yoke 17 by outsert molding on the outer peripheral surface of the rotor yoke 17.

  A ring-shaped rotor magnet 20 is provided on the inner peripheral surface of the cylindrical portion 17 a of the rotor yoke 17 so as to face the coil 14 of the stator 12. The magnet 20 is a plastic magnet in which S and N poles are alternately magnetized in the circumferential direction, and is fixed to the inner peripheral surface of the rotor yoke 17 with an adhesive.

  The rotor yoke 17 is rotated by press-fitting a boss portion 21 provided with a through hole 21a provided in the center portion of the flat plate portion 17b into an attachment portion 32 provided on the distal end side of the rotating shaft 31 supported by the bearing unit 30A. The shaft 31 and the shaft 31 are rotatably attached.

  In the motor 1 having the above-described configuration, when a drive current is supplied to the coil 14 on the stator 12 side by a predetermined energization pattern from a drive circuit unit provided outside the motor 1, the magnetic field generated in the coil 14 and the rotor The rotor 11 rotates integrally with the rotating shaft 31 by the action of the magnetic field from the 11-side rotor magnet 20. As the rotor 11 rotates, the fan 3 having a plurality of blades 19 attached to the rotor 11 also rotates integrally with the rotor 11. As the fan 3 rotates, the air outside the apparatus is sucked through an opening provided in the casing constituting the computer, and further, the inside of the casing is circulated, and the through-hole is circulated through the heat sink provided in the casing. By exhausting the air to the outside of the housing through the heat, heat generated from a heating element such as an electronic component such as a semiconductor integrated circuit element is dissipated to the outside of the computer body, and the computer body is cooled.

  Next, the configuration and structure of a bearing unit 30A according to an embodiment of the present invention suitable for use in the motor 1 will be described.

  As shown in FIGS. 1 to 4, the bearing unit 30A that rotatably supports the rotating shaft 31 of the motor 1 includes a radial bearing 33A that supports the rotating shaft 31 in the circumferential direction, and the radial bearing 33A. A passage forming member 34A formed on the outside, a passage forming member lid 40A for housing the passage forming member 34A, a backflow prevention mechanism 70, a check ball 80, a housing 60, a retaining washer 49, and the like are included.

  As shown in FIGS. 2 and 6, a radial bearing 33A suitable for application to the bearing unit 30A of the present invention has a cylindrical structure similar to the structure of the conventional radial bearing 33 shown in FIG. A rotation shaft insertion hole 33h is formed in the central portion, its upper end surface is formed as a rotation shaft release side end surface 33a, and its lower end surface is formed as a thrust bearing side end surface 33b. In this embodiment, three first grooves 51 are provided on the thrust bearing side end surface 33b, and in this embodiment, the second groove 52 is provided on the rotary shaft release side end surface 33a. In this embodiment, the third groove 53 is formed, and the second groove 52 and the third groove 53 communicate with each other above and below the first groove 51, respectively. The communication path 50 is formed.

  Furthermore, the lower part is a communication path at the corner between the rotary shaft release side end face 33a of the radial bearing 33A and the outer peripheral surface, that is, at the corner where each first groove 51 and each third groove 53 are connected. 50 is formed, and a semi-saddle-shaped sphere moving groove 71a having a slightly longer cross-sectional shape with a slightly open upper part and a slightly longer shape is formed.

  The material of the radial bearing 33A may be a sintered metal, a metal such as brass or stainless steel, or a resin. Further, as shown in FIG. 10, the radial bearing 33 </ b> A may be a hydrodynamic bearing provided with dynamic pressure generating grooves 43 and 44 on its inner peripheral surface.

  As shown in FIG. 3, the passage forming member 34 </ b> A has a cup shape like the structure of the passage forming member 34 shown in FIG. 13, and a thrust bearing 46 is formed on the inner surface of the bottom portion. The circular arc plate 36A that covers the top of each communication passage 50 is formed in order to secure the space passage of the groove of each communication passage 50, and the cylindrical portion is divided by the notch 35, and at the bottom, A space 37 that accommodates a flexible retaining washer 49 that can be pushed and expanded by inserting the rotating shaft 31 into the central portion and a space 38 that accommodates and supports the lower end portion 31b of the rotating shaft 31 are formed concentrically. Thus, a thrust space S is formed. These spaces 37 and 38 are also spaces that allow the lubricating oil L to circulate through the communication passage 50. Further, an engaging claw 39 is formed on the periphery of the opening inward.

  Furthermore, it opens slightly above the center of the inner peripheral surface of each arc-shaped plate 36A immediately below each engaging claw 39, and forms a pair with the semi-saddle-shaped sphere moving groove 71a having a slightly longer cross-section and a slightly longer cross section. A semi-cylindrical sphere moving groove 71b is formed.

  The semi-spheroid sphere moving groove 71b and the semi-spheroid sphere moving groove 71a are combined to have a substantially circular cross section, but the bowl-shaped length is slightly longer, that is, the bowl-shaped sphere moving groove 71. The lower part is the same as the diameter of the communication passage 50, and has a structure that forms a slightly open groove above.

  As shown in FIG. 4, the passage forming member lid 40 </ b> A is a donut-shaped flat and substantially disk-shaped member, and a rotation shaft insertion hole 40 h is formed in the center, and the center is formed on the outer peripheral surface. A semicircular arc shaped projection lid 72 is formed to block the semi-saddle-shaped sphere moving groove 71b immediately below the engaging claw 39 of the passage forming member 34A at an angular interval of 120 degrees. The passage forming member lid 40 is slightly larger than the diameter of the engaging claw 39 formed in the opening of the passage forming member 34, and the engaging claw 39 is pushed and expanded so as not to come out upward. It is a structure which is stopped and seals the opening of the passage forming member 34A.

  Furthermore, as one part constituting the backflow prevention mechanism 70, there is a check ball 80 as shown in FIG. The check ball 80 is a sphere having a diameter slightly smaller than the cross-sectional diameter of the bowl-shaped sphere moving groove 71 and can smoothly move up and down in the bowl-shaped sphere moving groove 71. As shown in FIG. In the lowered position state, the communication passage 50 is closed and the communication with the third groove 53 is blocked. When the communication passage 50 is in the upper position as shown in FIG. It is a size that allows communication, and has a check valve function. The vertical movement distance of the check ball 80, that is, the depth of the bowl-shaped ball moving groove 71 is not uniformly determined by the thickness, depth, etc. of the groove, but the diameter of the check ball 80 is 1.2. Double is enough.

  The material of the check ball 80 may be a general ballpoint pen such as steel or ceramic, or a material used for bearing, and may be a resin or a rubber-based material that has no problem with the lubricating oil L. Further, the size and weight of the check ball 80 are selected in consideration of the viscosity of the lubricating oil L.

  The thrust bearing 46 may be a hydrodynamic bearing or a pivot type bearing. In the bearing unit 30A of this embodiment, the lower end portion 31b of the rotary shaft 31 is spherical, and the passage forming member 34 is a resin to form a pivot type thrust bearing.

  Next, in order to assemble the bearing unit 30A of the present invention shown in FIG. 1 and FIG. 2, first, a retaining washer 49 is disposed in advance in the space 37 of the passage forming member 34A, and the radial bearing 33A is disposed therein. Then, the thrust bearing side end face 33b is fitted downward. In the fitting of the radial bearing 33A, the semi-cylindrical sphere moving grooves 71a of the radial bearing 33A are fitted so as to match the semi-cylindrical sphere moving grooves 71b of the arcuate plates 36A. By doing so, both unite and the bowl-shaped ball moving groove 71 is formed.

  Subsequently, a check ball 80 is inserted into each bowl-shaped sphere moving groove 71, and the passage forming member lid 40A is fitted from the upper opening of the passage forming member 34A so that the projection lid 72 is sealed above each of the check balls 80, and the radial The engagement claw 39 engages and fixes the bearing 33A so as to be in close contact with the rotary shaft release side end surface 33a.

  By assembling in this way, each first groove 51 of the radial bearing 33A is sealed with each arcuate plate 36A of the passage forming member 34A, each second groove 52 communicates with the thrust space S, and each third groove The grooves 53 are sealed with a passage forming member lid 40A to form space passages, respectively, and the lubricating oil L substantially the same as that of the conventional bearing unit 30C to which these space passages are connected can be circulated. A communication passage 50 is formed, and a backflow prevention mechanism 70, which is a major feature of the bearing unit 30A of the present invention, is formed.

  When the mold is used in this assembled state and the resin is sealed over the outer surface of the passage forming member 34A and the upper surface of the passage forming member lid 40A excluding the rotary shaft insertion hole 40h, the resin is exposed by the notches 35 of the passage forming member 34A. It can be covered with a resin housing 60 over a part of the outer peripheral surface of the radial bearing 33 and the outer surface of the arcuate plate 36 and over the upper surface of the passage forming member lid 40A.

  After that, when the rotary shaft 31 is inserted into the center portion of the rotary shaft insertion hole 40h of the passage forming member lid 40A, the rotary shaft insertion hole 33h of the radial bearing 33A, and the retaining washer 49 and pushed in, the structure shown in FIG. The bearing unit 30A of the present invention is obtained.

As a material of the housing 60, it is desirable to form a resin such as POM (polyoxymethylene), polyimide, LCP (liquid crystal polymer) by outsert molding.
In this way, the bearing unit 30A of the present invention can be assembled.

  Next, the operation of the bearing unit 30A of the present invention, in particular, the operation of the backflow prevention mechanism 70 will be described with reference to FIG.

  In the bearing unit A of the present invention, there is provided a communication passage 50 for short-circuiting the variation of the dynamic pressure generated between the two dynamic pressure generating grooves 32 as the rotary shaft 31 rotates and the variation of the static pressure generated as the dynamic pressure increases. However, if there is no short circuit in the communication passage 50, (the force due to the non-opening side pressure of the rotating shaft 31)> (the force due to the pressure on the opening side of the rotating shaft 31) with the rotation of the shaft rotation 31. In this case, a force (arrow Za, FIGS. 7 and 8B) for pushing up the rotating shaft 31 is generated. As a result, when the rotating shaft 31 is pushed out, the bearing unit 30A cannot function as a bearing. The backflow prevention mechanism 70 in the present invention functions to prevent such inconvenience.

  That is, when the pressure in the thrust space S becomes higher than the external air pressure, the check ball 80 is moved by the lubricating oil L along the semi-cylindrical ball moving groove 71b as shown in FIG. The communication passage 50 is pushed up to the lower surface, and the communication passage 50 is opened on the rotary shaft release side end surface 33a to release the pressure and prevent the rotary shaft 31 from floating from the thrust bearing 46.

  On the other hand, when the rotating shaft 31 receives a vibration external force that floats from the thrust bearing 46, the check ball 80 is positioned at the bottom of the bowl-shaped ball moving groove 71 and closes the communication passage 50 thereunder (FIG. 7, The arrow Zb) in FIG. 8A is a resistance force against the force that lifts the rotary shaft 31 from the thrust bearing 46 due to the dashpot effect.

  Therefore, when a vibration external force in the thrust (shaft) direction is applied to the rotating shaft 31, the resistance force increases in the direction in which the rotating shaft 31 floats, and in the direction in which the rotating shaft 31 returns to the thrust bearing 46 side. Since the resistance force becomes small, the vibration external force becomes a force pressing the rotating shaft 31 against the thrust bearing 46, and the bearing is stable against vibration.

  Therefore, in the bearing unit 30A of the present invention, the backflow prevention mechanism 70 operates and the communication passage 50 is closed when the rotating shaft 31 of the bearing unit 30A receives a pulling force from the housing 60 in the state of a single product or a rotating device. Therefore, the lubricating oil L does not flow, a large resistance force is generated by the dashpot effect, and the rotating shaft 31 can be prevented from being pulled away from the thrust bearing 46.

  As a result, it is difficult for air to enter from the outside of the bearing unit 30A due to seal breakage due to a decrease in the lubricating oil L surface, and a highly reliable bearing unit can be obtained.

  In addition, when the rotating shaft 31 receives an external force (vibrational) floating from the thrust bearing 46, when the rotating shaft 31 is displaced in the direction of floating from the thrust bearing 46, a large resistance force acts due to the dashpot effect. When an external force is applied in the direction in which the rotating shaft 31 is pressed against the thrust bearing 46, the dashpot effect is reduced, so that the rotating shaft 31 behaves so as to be pressed against the thrust bearing 46. For this reason, it becomes a thrust bearing strong against external force vibration.

  When the bearing unit 30A of the present invention is applied to a bearing of a rotating device such as a motor, more stability is obtained with respect to vibration in the thrust direction, and thrust suction for stabilizing the thrust vibration is obtained in the rotating device. When an auxiliary mechanism is added, such a thrust suction mechanism can be excluded, and the suction force of the thrust suction mechanism can be reduced. Furthermore, since the thrust suction force can be reduced, when the thrust bearing 46 is a pivot bearing, the effect of reducing the thrust load and reducing the wear and improving the reliability of the bearing unit can be obtained.

  As described above, the bearing unit of the present invention can be configured as a highly reliable bearing unit as compared with a conventional bearing unit.

  In the above embodiment, the motor is used as the rotating device. However, the bearing unit of the present invention is not limited to the bearing of the rotating shaft of the motor, but is a linear object such as a thread or a wire, and a wide width. It should be noted that the present invention can also be applied to bearings such as gyro rollers, idlers, capstans, pinch rollers, and the like used in an apparatus for winding a strip such as a film or a magnetic tape.

It is sectional drawing of the motor which is one of the rotation apparatuses of one Example of this invention. It is a cross-sectional side view of the bearing unit provided with the backflow prevention mechanism of one Example of this invention used for the bearing of the motor shown in FIG. FIG. 3A is an overall perspective view, FIG. 2B is a top view of FIG. 1A, and FIG. It is a cross-sectional side view on a line. It is a perspective view of a passage formation member lid suitable for use in the bearing unit of the present invention shown in FIG. It is a front view of a check ball. It is a perspective view of a radial bearing suitable for use in the bearing unit of the present invention shown in FIG. It is sectional drawing for operation | movement description of the bearing unit of this invention shown in FIG. It is a partially expanded sectional view for operation | movement description of the backflow prevention mechanism in the bearing unit shown in FIG. It is a section side view of the bearing unit of the 1st form of conventional technology. FIG. 10 is a cross-sectional perspective view showing an example of a dynamic pressure generating groove formed on the inner peripheral surface of the radial bearing shown in FIG. 9. FIG. 10 is a cross-sectional side view of the bearing unit when an undesirable state occurs in the bearing unit shown in FIG. 9. It is a cross-sectional side view of the bearing unit of the 2nd form of a prior art. FIG. 13 is a perspective view showing the shape of a communication passage formed between the passage forming member lid shown in FIG. 12 and a radial bearing. FIGS. 12 and 13 show the passage forming member, wherein FIG. A is an overall perspective view thereof, FIG. B is a top view thereof, and FIG. C is a cross-sectional view taken along line CC in FIG. . FIG. 13 is a cross-sectional side view of the bearing unit when an undesirable state occurs in the bearing unit shown in FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Motor of one Example of this invention, 3 ... Fan, 4 ... Fan case, 11 ... Rotor, 12 ... Stator, 14 ... Coil, 15 ... Core, 30A ... Bearing unit of one Example of this invention, 31 ... Rotating shaft, 32 ... Dynamic pressure generating groove, 33A ... Radial bearing, 33a ... Rotating shaft release side end surface of radial bearing 33A, 33b ... Thrust bearing side end surface of radial bearing 33A, 33h ... Rotating shaft insertion hole, 34A ... Passage forming member 35 ... notches, 36A ... arc-shaped plate, 37, 38 ... space, 39 ... engaging claw, 40A ... passage forming member lid, 40h ... rotating shaft insertion hole, 46 ... thrust bearing, 49 ... retaining washer, 50 ... Communication passage, 71 ... Hot ball movement groove, 71a, 71b ... Semi-hump ball movement groove, 72 ... Protrusion lid, 80 ... Check ball, S ... Thrust space, L ... Lubricating oil

Claims (8)

A cylindrical radial bearing in which a rotation shaft insertion hole for rotatably supporting the rotation shaft is formed at the center, and at least one groove is formed on an outer peripheral surface connecting the rotation shaft release side end surface and the thrust bearing side end surface;
A thrust bearing supporting the bottom inner surface in the axial direction, and a passage forming member formed with an arc-shaped plate covering at least the groove portion;
A passage forming member lid that covers the rotary shaft release side end surface of the radial bearing and has a rotary shaft insertion hole formed in a central portion;
The rotation of the radial bearing mounted in the passage forming member with the thrust bearing side end surface of the radial bearing facing the thrust bearing side and the groove portion of the outer peripheral surface covered with the arcuate plate With the shaft release side end face side sealed with the passage forming member lid to form a communication passage, the periphery of the radial bearing, the outer surface of the passage forming member, and the passage excluding the rotating shaft insertion hole portion A housing formed by integrally covering the surface of the forming member lid;
A lubricating oil filled in the housing;
A bearing unit comprising: a backflow prevention mechanism for the lubricating oil formed on the passage forming member lid side of the communication passage. The backflow prevention mechanism is
At least one communication passage formed on the outer peripheral surface of the radial bearing from the rotary shaft release side end surface side of the radial bearing to the thrust bearing side end surface;
A space passage formed by covering the communication passage with the arc-shaped plate of the passage forming member;
And a ball disposed so as to prevent the lubricating oil from flowing from the rotary shaft release side end surface side of the radial bearing to the thrust bearing side end surface side in the communication passage and the space passage. The bearing unit according to claim 1, wherein: The backflow prevention mechanism is
At least one communication passage formed from the rotary shaft release side end surface side of the radial bearing to the outer peripheral surface and the thrust bearing side end surface side;
A passage forming member lid that covers the rotary shaft release side end face side of the radial bearing;
A passage forming member covering the outer periphery of the radial bearing;
The lubricating oil filled in the communication passage, the thrust space of the thrust bearing, and the rotary shaft insertion hole of the radial bearing;
A semi-cylindrical sphere moving groove formed continuously on the rotary shaft release side end face side of the communication passage;
The other semi-cone-shaped sphere moving groove which is formed in the arc-shaped plate of the passage-forming member and forms a bowl-shaped sphere-moving groove when the communication passage is covered,
And a ball disposed in the bowl-shaped ball moving groove so as to prevent the lubricating oil from flowing in the communication passage from the rotary shaft release end surface side to the thrust bearing side end surface side. The bearing unit according to claim 1, wherein:   The bearing unit according to claim 3, wherein the depths of the two semi-cylindrical sphere moving grooves are substantially equal.   The bearing unit according to claim 1, wherein the radial bearing is made of sintered metal.   2. The bearing unit according to claim 1, wherein the radial bearing is a hydrodynamic bearing in which a dynamic pressure generating groove is provided on an inner peripheral surface of the rotation shaft insertion hole. A cylindrical radial bearing in which a rotation shaft insertion hole for rotatably supporting the rotation shaft is formed at the center, and at least one communication passage is formed on the outer peripheral surface connecting the rotation shaft release side end surface and the thrust bearing side end surface; ,
A thrust bearing axially supported on the inner surface of the bottom, and a passage forming member formed with an arc-shaped plate covering at least the communication passage portion;
A passage forming member lid that covers the rotary shaft release side end surface of the radial bearing and has a rotary shaft insertion hole formed in a central portion;
The rotational shaft release of the radial bearing mounted in the passage forming member with the thrust bearing side end face of the radial bearing facing the thrust bearing side and the communication passage portion covered with the arcuate plate With the side end face side sealed with the passage forming member lid, the periphery of the radial bearing, the outer surface of the passage forming member, and the surface of the passage forming member lid are integrated, except for the rotation shaft insertion hole portion. A housing formed by covering with,
A lubricating oil filled in the housing;
A rotation shaft that is rotatably supported by the radial bearing of the bearing unit that includes a backflow prevention mechanism for the lubricating oil that is formed on the passage forming member lid side of the communication passage. A rotating device characterized by being configured. The rotating device according to claim 7, wherein the rotating shaft is a rotor shaft of a motor including a stator and a rotor.

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