JP3978999B2 - Hydrodynamic bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic bearing device.
[0002]
[Prior art]
Conventionally, a hydrodynamic bearing device shown in FIG. 4 is known. The hydrodynamic bearing device includes a housing 41 and a rotating shaft 43 that is inserted into the axial through hole 42 of the housing 41 with a predetermined gap so as to be relatively rotatable, and a shaft end portion remains on the rotating shaft 43. The flange 44 thus formed is fitted into an annular recess 45 formed in the inner diameter surface of the through hole 42 of the housing 41 with a predetermined gap therebetween, and the upper surface 44a of the flange 44 (the upper surface in FIG. 4 is referred to as the upper surface). The through hole 42 of the housing 41 is opened 47 to the outside, the lubricating fluid 46 is sealed between the housing 41 and the rotary shaft 43, and the upper surface 44a and the lower surface 44b of the flange (the lower surface in FIG. Thrust dynamic pressure generating portions B1 and B2 are provided between the annular recess 45 and the surfaces 45a and 45b facing the flange upper and lower surfaces 44a and 44b. . The opening 47 between the housing 41 and the rotary shaft 43 is labyrinth sealed. The thrust dynamic pressure generating portions B1 and B2 are configured by forming dynamic pressure generating grooves 48 and 49 on the upper surface 44a and the lower surface 44b of the flange 44, respectively. If necessary, the dynamic pressure generating grooves 48 and 49 are formed. May be formed on the inner side of the annular recess 45a, 45b. Further, a dynamic pressure generating groove 50 is formed on the rotary shaft 43 on the flange lower surface 44 b side, and a radial dynamic pressure generating portion B 3 is formed between the rotary shaft 43 and the housing 41. The dynamic dynamic pressure generating groove 50 of the radial dynamic pressure generating part B3 may be formed on the inner diameter surface of the through hole 42 of the housing 41.
[0003]
Further, since the through hole 42 of the housing 41 on the flange upper surface 44a side of the rotating shaft 43 is in an open state 47 to the outside, the upper portion of the through hole 42 of the housing 41 is repeated by repeatedly starting and stopping the rotation of the rotating shaft 43. The lubricating fluid 46 may move to the open portion 47 side (on the upper surface 44a side of the flange 44), and the lubricating fluid 46 may leak out from the open portion 47 that serves as a labyrinth seal. It is necessary to prevent the lubricating fluid 46 from moving to the opening 47. For this reason, an axial through hole 51 parallel to the axis passing through the flange upper and lower surfaces 44 a and 44 b is formed at the root portion of the flange 44 of the rotating shaft 43, and is used for circulating the lubricating fluid 46.
[0004]
[Problems to be solved by the invention]
In the conventional hydrodynamic bearing device, leakage of the lubricating fluid 46 to the outside of the flange 44 is prevented without reducing the load capacity of the thrust dynamic pressure generating portions B1 and B2 formed on the flange 44 of the rotary shaft 43. Since the axial through hole 51 has to be formed, there is a problem that the diameter of the flange 44 is increased and the torque is increased.
[0005]
Accordingly, an object of the present invention is to provide a hydrodynamic bearing device that eliminates an increase in torque due to an increase in the shaft flange diameter and prevents leakage of lubricating fluid to the outside.
[0006]
[Means for Solving the Problems]
As a means for solving the above-mentioned problems, the invention of claim 1 is provided with a relatively rotating housing and a shaft inserted through an axial through hole of the housing with a predetermined gap therebetween, and a flange formed on the shaft. Is inserted into an annular recess formed in the inner surface of the through hole of the housing with a predetermined gap therebetween, and lubricating fluid is sealed between the housing and the shaft, and the upper and lower surfaces of the flange and the upper and lower surfaces of the flange of the annular recess In the hydrodynamic bearing device in which the thrust dynamic pressure generating portion is provided between the surface and the housing, the housing portion facing the upper surface of the flange of the shaft is connected to the bottom portion of the annular recess from the inner diameter surface of the housing. A passage is formed, and the communication passage is formed by crossing the radial hole formed so as to extend radially outward and perpendicular to the axial direction from the inner diameter surface of the housing. Is formed from a cut portion which opens into the bottom of the annular recess, the cut portion, together with the spread in a direction away from the annular recess in the axial direction from the radial bore, spreads larger diameter side than the annular recess, and A predetermined gap formed by the flange and the bottom of the annular recess is formed so as to communicate in the axial direction, and the radial hole is opened in the radially innermost part of the cut portion .
[0007]
The invention according to claim 2 is characterized in that the communication passage is formed symmetrically about the axis of the housing .
[0008]
Furthermore, in the invention of claim 3, the housing is characterized in that an upper divided housing and a lower divided housing which are divided in the axial direction at the position of the annular recess are integrally formed .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A specific embodiment of the present invention will be described below with reference to FIG. The hydrodynamic bearing device includes a housing 1 and a rotary shaft 3 that is inserted into the axial through hole 2 of the housing 1 with a predetermined gap so as to be relatively rotatable, and a shaft end portion remains on the rotary shaft 3. The flange 4 thus formed is fitted into an annular recess 5 formed on the inner diameter surface of the through hole 2 of the housing 1 with a predetermined gap therebetween, and the upper surface 4a of the flange 4 (the upper surface in FIG. The through hole 2 of the housing 1 on the side is opened to the outside as an open portion 7, and a lubricating fluid 6 is sealed between the housing 1 and the rotary shaft 3, and the upper surface 4a and the lower surface 4b of the flange 4 (FIG. 1). Thrust dynamic pressure generating portions B1 and B2 are provided between the lower surfaces of the annular recess 5 and the surfaces 5a and 5b of the annular recess 5 facing the flange upper and lower surfaces 4a and 4b. The open portion 7 between the housing 1 and the rotating shaft 3 is a labyrinth seal. The thrust dynamic pressure generating portions B1 and B2 are configured by forming dynamic pressure generating grooves 8 and 9 on the upper surface 4a and the lower surface 4b of the flange 4, respectively. However, if necessary, the dynamic pressure generating grooves 8 and 9 are formed. May be formed on the inner surface 5a, 5b side of the annular recess 5 . Further, a dynamic pressure generating groove 10 is formed on the rotary shaft 3 on the flange lower surface 4 b side, and a radial dynamic pressure generating portion B 3 is formed between the housing 1 and the rotary shaft 3. The dynamic pressure generating groove 10 of the radial dynamic pressure generating portion B3 may be formed on the inner diameter surface of the through hole 2 of the housing 1.
[0010]
Further, the housing 1 is integrated by press-fitting, bonding, or the like, with the upper divided housing 1a and the lower divided housing 1b divided in the axial direction at the flange upper surface 4a side of the rotating shaft 3 and at the position of the annular recess 5. Has been formed. A large-diameter step portion 12 is formed on the flange 4 side on the inner diameter surface of the through hole 2 of the upper divided housing 1a, and a communication passage 11 that opens from the step portion 12 to the bottom portion 5c of the annular recess 5 is formed. Has been. The communicating path 11, as will be appreciated Oite better in Figure 2, in two positions 180 degrees opposite position of the upper split housing 1a, the inner diameter surface of the through hole 2 in the upper housing segment 1a to the outer diameter side The formed radial hole 11a, the radial hole 11a formed on the outer diameter side from the inner diameter surface of the through hole 2 of the upper divided housing 1a, and the radial hole formed in the outer diameter portion of the upper divided housing 1a. It is formed from a cut portion 11b that intersects with 11a and opens into the bottom portion 5c of the annular recess 5. The cut portion 11b also functions as a lubricating fluid pool and helps prevent the lubricating fluid from running out. Further, in the configuration of FIG. 2, the cut portion 11b is formed by cutting the upper divided housing 1a linearly in the tangential direction of the outer diameter surface. This structure is advantageous in that when the bearing size is small, it is easy to secure a volume as an oil reservoir, and processing is easy. FIG. 3 shows another embodiment of the excision part, and this excision part 11b is excised by an arc having a center on the outer diameter surface side in the upper divided housing 1a. This structure is advantageous when the bearing size is relatively large from the viewpoint of securing the volume of the oil reservoir, and is further advantageous in that processing is facilitated. Further, the radial hole of the communication passage 11 is directly formed in the upper housing 1a by a drill or the like, but a radial groove is formed on the lower surface of the upper housing 1a, and the upper housing is covered so as to cover the radial groove. A separate lid may be integrated with the inner surface of 1a to substantially form the radial hole 11a.
[0011]
In the embodiment shown in FIG. 1, the housing 1 is divided into the upper divided housing 1a and the lower divided housing 1b. However, by doing so, the processing of the communication path 11 becomes very easy.
[0012]
Next, the operation of the communication path 11 will be described. The gap between the bearing gap of the thrust dynamic pressure generating portion B1, B2 which varies by start and stop of the rotation shaft 3 is changed, the recess 5 of the flange top surface 4a and the housing 1 of the rotary shaft 3, i.e. the upper portion of the thrust dynamic When the bearing clearance of the pressure generating portion B1 becomes small, the lubricating fluid 6 near the outer diameter side of the upper thrust dynamic pressure generating portion B1 and near the cutout portion 11b of the communication passage 11 is drawn to the flange lower surface 4b side. As a result, the lubricating fluid 6 in the through hole 2 of the housing 1 on the upper surface 4a side of the flange 4 is received by the step portion 12 and is efficiently drawn into the communication passage 11 to smoothly increase the bearing clearance. Accordingly, the lubricating fluid 6 in the vicinity of the external opening 7 of the through hole 2 of the housing 1 is prevented from being pushed out and leaked.
[0013]
In addition, although the case where the axis | shaft 3 rotates was shown in the said embodiment, the axis | shaft 3 may be fixed and the housing 1 may rotate.
[0014]
【The invention's effect】
Thus, in the first to third aspects of the present invention, since the shaft flange does not have an axial through-hole penetrating the top and bottom surfaces, the flange diameter can be reduced while maintaining the load capacity of the thrust and dynamic pressure generating portion. Torque can be reduced. Further, since the lubricating fluid smoothly circulates when the bearing clearance of the thrust dynamic pressure generating portion is reduced by the communication passage formed in the housing, leakage from the outside open portion of the through hole of the housing is prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a fluid dynamic bearing device according to an embodiment of the present invention.
FIG. 2 is a plan view seen from the upper surface of the flange of FIG. 1, and is an embodiment of the communication path of the present invention.
FIG. 3 is a plan view seen from the upper surface of the flange of FIG. 1, and is another embodiment of the communication path of the present invention.
FIG. 4 is a cross-sectional view of a conventional hydrodynamic bearing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 1a Upper division | segmentation housing 1b Lower division | segmentation housing 2 Through hole 3 Rotating shaft 4 Flange 5 Annular recessed part 6 Lubricating fluid 7 Opening part 8 Dynamic pressure generating groove 9 Dynamic pressure generating groove 10 Dynamic pressure generating groove 11 Communication path 11a Radial hole 11b Excision

Claims (3)

A housing that rotates relative to the housing, and a shaft that is inserted into the axial through hole of the housing with a predetermined gap therebetween. A flange formed on the shaft has a predetermined gap in an annular recess formed on the inner surface of the through hole of the housing. A lubricating fluid is sealed between the housing and the shaft, and a thrust dynamic pressure generator is provided between the upper and lower surfaces of the flange and the surface of the annular recess facing the upper and lower surfaces of the flange. In the hydrodynamic bearing device, a communication path that opens from the inner diameter surface of the housing to the bottom of the annular recess is formed in the housing portion facing the flange upper surface side of the shaft, and the communication path has a diameter from the inner diameter surface of the housing. A radial hole formed so as to extend outward in the direction and perpendicular to the axial direction, and a cut portion that intersects the radial hole and opens into the bottom of the annular recess, Removal unit, together with the spread in a direction away from the annular recess in the axial direction from the radial bore, than the annular recess spread large diameter side, and the axial direction at a predetermined gap and the bottom to form the flange and the annular recess A hydrodynamic bearing device, wherein the hydrodynamic bearing device is formed so as to communicate with each other, and the radial hole is opened in an innermost radial direction of the cut portion .   The hydrodynamic bearing device according to claim 1, wherein the communication path is formed symmetrically about the axis of the housing.   3. The hydrodynamic bearing device according to claim 1, wherein the housing is formed by integrating an upper divided housing and a lower divided housing which are divided in the axial direction at an annular recess position. 4.

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