JP2005090637A - Dynamic pressure bearing, method of manufacturing the dynamic pressure bearing, and rotary device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing manufacturable at low cost, not causing the leakage of a lubricating oil, and having excellent reliability, a method of manufacturing the dynamic pressure bearing, and a rotary device. <P>SOLUTION: The dynamic pressure bearing 20A of the first embodiment of this invention comprises a bearing member 30 formed by combining a plurality of partial arc members 30A and 30B having a dynamic pressure generating groove 31 formed in the inner peripheral thereof and a resin housing 40 in which step parts 41A and 41B having diameters larger than the inner diameter of the bearing member 30 are formed and formed by out-sert molding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dynamic pressure bearing configured to generate dynamic pressure in a lubricating fluid and to relatively rotatably support a shaft member and a bearing member by the dynamic pressure, a manufacturing method thereof, and a rotating device. .

  First, the configuration, structure, and manufacturing method of a conventional hydrodynamic bearing will be described with reference to the drawings.

  FIG. 10 is a perspective view of a conventional hydrodynamic bearing, FIG. 11 is an external perspective view showing an assembled state of the hydrodynamic bearing device shown in FIG. 10, and FIG. 12 shows the structure of a general hydrodynamic bearing device. FIG. These figures correspond to FIGS. 1, 5, and 8, respectively, among the figures published in the published patent and Japanese Laid-Open Patent Publication No. 2000-170746, which are reprinted.

  In this dynamic pressure bearing, three partial arcuate members 15a provided with dynamic pressure generating grooves 2b (FIG. 12) are combined to form a bearing sleeve (bearing member) 15, which is held by the bearing holder 12 to be a bearing. It is said.

  In this method of manufacturing a dynamic pressure bearing, the dynamic pressure generating groove 2b and the partial arcuate member 15a are formed by a powder metallurgy method or the like and assembled into an annular shape to form a bearing. Compared with the etching and rolling methods, which are means for forming the generation grooves, the manufacturing method is simple and excellent.

  In this patent, the main point is to combine the partial arc-shaped members 15a with high accuracy, and the feature is that the concave and convex grooves 15f (FIG. 11) are provided on the surfaces that are in contact with each other for positioning.

  The partial arc-shaped members 15 a are fastened together by press-fitting an annular member in which the partial arc-shaped members 15 a are combined into the annular housing 12.

JP 2000-170746 (pages 4-6, FIG. 1, FIG. 5, FIG. 8)

  However, in the above-described conventional technique in which the partial arc-shaped members 15a are combined with the concaves and convexes, it is impossible to prevent leakage of the lubricating oil no matter how the contact surfaces of the partial arc-shaped members 15a are brought into close contact with each other. If the bearing sleeve 15 made of the partial arcuate member 15a is press-fitted into the housing 12, there is a disadvantage that the radial accuracy of the inner periphery of the bearing sleeve 15 that becomes the bearing member is reduced.

  Further, since the positional accuracy between the partial arcuate members 15a depends only on the uneven portion 15f provided on the contact surface, there is a drawback that it is difficult to maintain the accuracy of the bearing inner diameter.

  That is, the conventional hydrodynamic bearing has a drawback that it is difficult to obtain good lubrication.

  The dynamic pressure bearing of the present invention is provided with a bearing member formed by combining a plurality of partial arc-shaped members formed with dynamic pressure generating grooves on the inner periphery, and a step portion having a diameter larger than the inner diameter of the bearing member, And a resin housing member formed by outsert molding.

  The method for manufacturing a hydrodynamic bearing according to the present invention includes a stepped portion having a diameter larger than the inner diameter of the bearing member by combining a plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery thereof. The resin housing member provided with is formed by outsert molding.

  Furthermore, the rotating device of the present invention is provided with a bearing member formed by combining a plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery, and a step portion having a diameter larger than the inner diameter of the bearing member. A shaft having a tapered portion formed at least at one end is inserted into a dynamic pressure bearing having a resin housing formed by outsert molding, and the diameter thereof increases toward the center portion. Is arranged at a position facing the stepped portion.

  The hydrodynamic bearing according to the present invention forms a bearing member by combining a plurality of partial arc-shaped members, resin is molded around the bearing member by outsert, and a resin housing member having a stepped shape is seamless. Therefore, it was possible to obtain a hydrodynamic bearing that is inexpensive and excellent in reliability without leakage of lubricating oil.

  In addition, since the multiple partial arc-shaped members are fixed together by outsert molding and resin housing in a combined state with respect to the inner periphery, the inner diameter of the bearing member is inexpensive and does not leak lubricating oil A hydrodynamic bearing with good accuracy and excellent reliability can be obtained.

  Further, by sizing the inner circumference of the bearing after molding of the resin housing, it is possible to obtain a dynamic pressure bearing with a better roundness of the inner diameter and better radial accuracy.

  Furthermore, the rotating device of the present invention can retain a large amount of lubricating oil and can be resistant to environmental changes such as expansion and contraction of the lubricating oil due to temperature changes.

  The present invention covers a resin housing member in which a step portion having a diameter larger than the inner diameter of a bearing member formed by combining a plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery is formed. A hydrodynamic bearing that does not leak oil has been realized.

  Hereinafter, a dynamic pressure bearing, a manufacturing method thereof, and a rotating device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a sectional view of a fluid dynamic bearing according to a first embodiment of the present invention, and FIG. 2 is a partial arc member of the fluid dynamic bearing incorporated in the fluid dynamic bearing shown in FIG.

  In FIG. 1, reference numeral 20A denotes a dynamic pressure bearing according to the first embodiment of the present invention. The dynamic pressure bearing 20A includes a bearing member 30 composed of a plurality of partial arcuate members 30A and 30B, outer peripheral surfaces thereof, and It is comprised from the resin housing 40 which coat | covered both end surfaces.

  As shown in FIG. 2, the partial arc-shaped members 30 </ b> A and 30 </ b> B are each formed with a dynamic pressure generating groove 31 such as a herringbone shape on the inner peripheral surface, and are made of sintered metal, nylon, polyimide, liquid crystal polymer, or the like. It is made of resin. The bearing member 30 is configured by a plurality of such partial arcuate members 30A and 30B, in the illustrated example, two semicircular partial arcuate members 30A and 30B abut end faces. The joint J between the partial arc-shaped members 30 </ b> A and 30 </ b> B is provided at the bottom of the dynamic pressure generating groove 31. Providing the joint J at the bottom of the dynamic pressure generating groove 31 has an advantage that it is easy to maintain the inner peripheral accuracy of the dynamic pressure bearing 20A.

  The resin housing 40 is an outsert described later so that step portions 41A and 41B having an inner diameter larger than the inner diameter of the bearing member 30 are formed so as to cover a part of the circumferential surface and both end surfaces of the bearing member 30. It is formed so as to cover the bearing member 30 by a molding method.

  As described above, the hydrodynamic bearing 20A according to the present invention is a state in which the circumferential surface and both end surfaces continuous to the circumferential surface and the both end surfaces thereof are provided with the step portions 41A and 41B in a state where the plurality of partial arcuate members 30A and 30B are combined. Since the resin molding is performed by the outsert molding method, the joint J between the two arcuate members 30A and 30B is seamlessly covered with the resin housing 40, and the lubricating oil L leaks from the joint J to the outside of the hydrodynamic bearing 20A. There is nothing to do.

  Next, a manufacturing method of the hydrodynamic bearing 20A of the present invention will be described with reference to FIGS. FIG. 3 is a process diagram showing a method for manufacturing a dynamic pressure bearing according to the present invention, and FIG. 4 is a cross-sectional view showing a sizing process for the dynamic pressure bearing obtained in the manufacturing process of FIG.

  First, as shown in FIG. 3A, partial arc-shaped members 30A and 30B are formed simultaneously with the dynamic pressure generating groove 31 using a powder metallurgy method, a resin mold, etc., and a pair of partial arc-shaped members 30A and 30B are prepared. To do.

  Next, as shown in FIG. 3B, the partial arcuate members 30A and 30B are combined using the upper pin 52 and the lower pin 53 in the resin molding die 50 on the basis of the inner diameter of the bearing member 30, They are combined to form a cylindrical bearing member 30. At this time, both end portions of the bearing member 30 may be sandwiched between the large diameter portions 521 and 531 of the upper pin 52 and the lower pin 53 (FIG. 3C).

  Resin R is injected into the mold 50 from the gate 51 of the mold 50 to form the resin housing 40 (FIGS. 3A and 3C). At this time, the large diameter portions 521 and 531 of the upper pin 52 and the lower pin 53 form not only the step portions 41A and 41B at both axial ends of the bearing member 30, but also the end portions of the step portions 41A and 41B. Since the structure is hermetically sealed by 41A and 41B, there is an important function of preventing the resin R from entering the inner peripheral portion of the bearing member 30.

  Further, when the bearing member 30 is made of a sintered metal or the like by a powder metallurgy manufacturing method, as shown in FIG. 4, a sizing bar 60 is used after the sizing process as shown in FIG. An accuracy of 30 inner diameters can be obtained.

The above is the manufacturing method of the hydrodynamic bearing of the present invention, but the important point is
1) Since the positioning of the partial arc-shaped members 30A and 30B is directly performed on the most important inner peripheral surface, the inner peripheral accuracy of the bearing member 30 can be easily obtained and good lubrication can be obtained 2). By forming the resin housing 40 by outsert molding, the seam J can be completely sealed, so that the lubricating oil L does not leak from the seam J and good lubrication can be obtained. By providing the portions 41A and 41B, not only can the partial arc-shaped members 30A and 30B be fixed during molding, but also the resin R can be reliably prevented from flowing into the inner peripheral portion of the bearing member 30 during outsert molding. 4) Furthermore, the inner circumference accuracy can be maintained and good lubrication can be obtained. 4) Further, a sizing bar 60 is inserted into the inner circumference of the bearing member 30 to cover the sizing process. Can be, it is possible to obtain the more inner diameter accuracy, good lubrication can be obtained. In addition, by providing a sizing step at the end, the roundness and diameter accuracy of the inner circumference of the bearing member 30 can be easily obtained even when the partially arcuate members 30A and 30B are assembled in a slightly shifted state. There is an advantage such as.

  FIG. 5 is a cross-sectional view showing a motor 100 which is one of rotating devices on which the hydrodynamic bearing 20A of the present invention is mounted.

  The motor 100 is shown as a fan motor in which a fan 120 is attached to a shaft 110. Since the motor 100 combines the partial arc-shaped members 30A and 30B to form the bearing member 30, and the periphery is seamlessly covered with the resin housing 40 by outsert molding, the reliability is low and the leakage of the lubricating oil L does not occur. It is a highly efficient motor.

  Furthermore, the advantage of providing the step portions 41A and 41B will be described with reference to FIG. The step portions 41A and 41B are provided not only to prevent the resin R from entering the inner peripheral surface of the bearing member 30 during outsert molding, but also as shown in FIG. By disposing the tapered portion 111 formed on the shaft 110 so as to face the surface, it can also be used as a component of a surface tension seal using a pressure gradient. Here, the taper portion 111 is a taper whose diameter increases toward the inside of the bearing member 30.

  Since the tapered portion 111 is disposed opposite to the step portions 41A and 41B having a diameter larger than the inner periphery of the bearing member 30, the taper portion 111 is larger than the tapered portion 111 provided opposite to the inner peripheral surface of the bearing member 30. Since the lubricating oil L can be held, there is an effect that the lubricating oil L is resistant to environmental changes such as expansion and contraction of the lubricating oil L due to temperature changes. In other words, the provision of the step portions 41A and 41B has an important role in preventing the resin R from wrapping around the inner peripheral surface of the bearing member 30 when the resin housing 40 is formed. It is also important as an element that constitutes a surface tension seal that is resistant to changes.

  In the first embodiment, when the bearing member 30 is configured, the partial arc-shaped members 30A and 30B are combined into a cylindrical shape, and are held in a state where the roundness of the inner peripheral surface of the bearing member 30 is obtained. Difficult to place in. Therefore, in the manufacturing method of the hydrodynamic bearing 20A of the first embodiment, it is desirable that the roundness of the inner peripheral surface of the bearing member 30 is obtained through a sizing process.

  However, the hydrodynamic bearing, the manufacturing method thereof, and the rotating device of the second embodiment are obtained by partially improving this point, and the structure and the manufacturing method will be described with reference to FIGS. .

  The dynamic pressure bearing 20B of the second embodiment shown in FIG. 9 is bound to the outer peripheral surface of the bearing member 30 in which the partial arc-shaped members 30A and 30B are combined with an elastic band 61 such as a rubber band, and then the first The resin R is injected into the mold 50 by outsert by the manufacturing method described in the embodiment, and the resin housing 40 in which the step portions 41A and 41B are formed is formed.

  In this case, as shown in the plan view of FIG. 8A, if there is an error in the external dimensions of the pair of partial arcuate members 30A and 30B, the partial arcuate members 30A and 30B are combined to form the elastic band 61. As shown in FIG. 8A, the bound bearing member 30 tends to have a perfect circle on the outer peripheral surface of the bearing member 30, but the inner peripheral surface is slightly shifted (several μm). However, when outsert molding is performed with the mold 50, the upper pin 52 and the lower pin 53 are inserted from both ends of the bearing member 30 to the inner peripheral portion, as shown in FIG. The partial arc-shaped members 30 </ b> A and 30 </ b> B are displaced on the outer peripheral surface to form a step, but the inner peripheral surface is a perfect circle and can smoothly support the shaft 110 constituting the motor 100.

  Next, as shown in FIG. 9, a groove 32 having a width and a depth in which the elastic band 61 fits may be formed at the same height position on the outer peripheral surface of each of the partial arcuate members 30A and 30B. By forming such a concave groove 32, it is possible to efficiently perform a combination operation of both partial arc-shaped members 30A and 30B, and it is possible to keep the tightened elastic band 61 at a fixed position.

  As described above, the description has been given by taking the dynamic pressure bearing of the motor as an example, but the present invention is not limited to the dynamic pressure bearing of the motor. It should be noted that the present invention can also be applied to a dynamic pressure bearing such as a dynamic pressure bearing of a normal rotating device or a bearing for a micromachine, a manufacturing method thereof, and a rotating device.

It is sectional drawing of the dynamic pressure bearing of 1st Example of this invention. 2 is a partial arc-shaped member of a dynamic pressure bearing incorporated in the dynamic pressure bearing shown in FIG. 1. It is process drawing which shows the manufacturing method of the dynamic pressure bearing of this invention. It is sectional drawing which shows the sizing process with respect to the hydrodynamic bearing obtained by the manufacturing process of FIG. It is sectional drawing of the fan motor incorporating the dynamic pressure bearing of 1st Example of this invention. It is a partially expanded sectional view of the dynamic pressure bearing of 1st Example of this invention. It is sectional drawing of the dynamic pressure bearing of 2nd Example of this invention. It is a top view of the bearing member which is a structural member of the dynamic pressure bearing of 2nd Example of this invention. It is a perspective view of the bearing member suitable for the dynamic pressure bearing of 2nd Example of this invention. It is a perspective view of a conventional hydrodynamic bearing. It is a disassembled perspective view of the conventional dynamic pressure bearing. It is a top view of the bearing member used for FIG.

Explanation of symbols

20A Dynamic pressure bearing of the first embodiment of the present invention 20B Dynamic pressure bearing of the second embodiment of the present invention 30 Bearing member 30A, 30B Partial arc member 31 Dynamic pressure generating groove 40 Resin housing 41A, 41B Resin housing 40 Step part 50 Resin molding die 51 Gate 52 Upper pin 521 Large diameter part 53 Lower pin 531 Large diameter part 60 Sizing bar 61 Elastic band 100 Motor 110 Motor 100 shaft 111 Shaft 110 taper part L Lubricating oil R Resin

Claims (7)

A bearing member formed by combining a plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery;
A hydrodynamic bearing comprising: a step portion having a diameter larger than the inner diameter of the bearing member; and a resin housing formed by outsert molding.   2. The hydrodynamic bearing according to claim 1, wherein the joint portion of the partial arc-shaped member is provided at the bottom of the dynamic pressure generating groove.   A plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery are combined to form a bearing member, and a resin housing member provided with a step portion having a diameter larger than the inner diameter of the bearing member is formed by outsert molding. A method of manufacturing a hydrodynamic bearing, characterized by comprising:   The plurality of partial arcuate members are combined and tightened with an elastic band to form a bearing member, and a resin housing member provided with a step portion having a diameter larger than the inner diameter of the bearing member is formed by outsert molding. A method for manufacturing a hydrodynamic bearing.   The method for manufacturing a hydrodynamic bearing according to claim 3 or 4, wherein inner peripheral portions of the plurality of partial arcuate members are used as a reference.   A plurality of partially arcuate members having dynamic pressure generating grooves on the inner periphery are combined to form a bearing member, and a resin housing member having a step portion having a diameter larger than the inner diameter of the bearing member is formed by outsert molding. A method of manufacturing a hydrodynamic bearing, comprising: sizing the inner peripheral portion of the bearing portion after forming. A bearing member formed by combining a plurality of partial arc-shaped members having dynamic pressure generating grooves formed on the inner periphery;
A hydrodynamic bearing having a step portion having a diameter larger than the inner diameter of the bearing member and having a resin housing formed by outsert molding increases in diameter toward the center portion. A rotating device comprising: a shaft having a tapered portion formed at least at one end; and the tapered portion being arranged at a position facing the stepped portion.