JPH03249418A - Dynamic pressure bearing rotation device - Google Patents

Abstract

PURPOSE:To prevent unnecessary lifting or escaping of a rotational shaft by fitting multiple protruded members provided on the rotational shaft with a spring member, in a recessed part of a sleeve in a non-contact condition. CONSTITUTION:Multiple protruded members 19 provided on a rotational shaft 1 by a spring member 18 are fitted in a recessed part 16 of a sleeve 2 in a non-contact condition. By making the amount D corresponding to the outer diameter of the protruding member 19 larger than an inner diameter Sd of the sleeve 2, in a condition where a load is not given to the spring member 18, as well as where centrifugal force is given to the spring member 18 by rotation, the rotational shaft 1 is prevented from being unnecessarily lifted up and thereby being escaped from the sleeve 2 that swirled air in a lubricating oil, even when the force works in a direction where the rotational shaft 1 is escaped from the sleeve 2.

Description

DETAILED DESCRIPTION OF THE INVENTION C. Field of Industrial Application The present invention relates to a hydrodynamic bearing rotating device, and relates to a rotating device used, for example, in a deflection scanning device used in a laser beam printer or the like.

[Prior Art] In recent years, the demand for rotating devices that rotate at high speed or with high precision has been increasing, and in order to obtain high-precision rotating devices, especially for laser beam printers, hydrodynamic bearings that rotate without contact are being used. It is used. FIG. 5 shows a deflection scanning rotation device for a laser beam printer using a hydrodynamic bearing. The rotating shaft 1 and the sleeve 2 are rotatably fitted, and a thrust plate 3 is disposed at the lower end of the sleeve 2 together with a fixed plate 4, and is fixed to an outer cylinder 5.

A flange 6 is fixed to the rotating shaft 1. A rotating polygon mirror 7 is fixed to the upper part of the flange 6, and a yoke 9 to which a driving magnet 8 is fixed is fixed to the lower part. A stator 10 is fixed to the outer cylinder 5 at a position facing the drive magnet 8. Here, the thrust plate 3 is provided with shallow grooves 11 on its surface facing the end of the rotating shaft 1 to form a hydrodynamic thrust bearing, and holes 12 and grooves 13 for circulation of lubricating fluid. It is being Further, a herringbone-shaped shallow dipping 14 is carved on the outer circumferential surface of the rotating shaft 1 at a position facing the inner circumferential surface of the sleeve 2, thereby forming a hydrodynamic radial bearing.

Furthermore, a shallow spiral groove 15 is cut in the vicinity of the sleeve opening to allow lubricating fluid to flow into the dynamic pressure thrust bearing. Further, the sleeve 2 is provided with a recess 16 at a position between the herringbone-shaped shallow groove 14 and the spiral shallow groove 15, as well as a small diameter hole 17, so that liquid (oil, grease, etc.) can be added to the lubricating fluid. etc.) to ensure the stability of hydrodynamic bearings.

[Problems to be Solved by the Invention] However, the above conventional example has the following drawbacks in order to ensure a stable hydrodynamic bearing.

In other words, after the hydrodynamic bearing has been assembled, when an impact is applied to the rotating body, the rotating body lifts up more than necessary and air gets mixed in with the lubricant (oil, grease, etc.), resulting in a stable hydrodynamic bearing rotating device. There were cases where the characteristics could not be obtained.

Further, if the rotating body is carelessly lifted, the rotating body may be pulled out from the fixed member. Therefore, handling of the dynamic pressure bearing after assembly is completed is troublesome.

The present invention has been made in view of the drawbacks of the prior art described above, and an object of the present invention is to provide a hydrodynamic bearing in which a rotating body and a fixed member are reliably connected to each other.

[Means and effects for solving the problem] In order to achieve the above object, according to the present invention, a recess is provided on either one of the fitting surfaces of the shaft and the sleeve, and a member is fitted into the recess without contact. By attaching one to the other, the rotating body is prevented from being lifted more than necessary from the fixed member and from being removed from the fixed member.

[Embodiment FIG. 1 is a drawing showing an embodiment of the present invention. Components that are the same as those in FIG. 5 and have the same functions are designated by the same numbers, and ``a'' is omitted.

The rotating shaft 1 and the sleeve 2 are rotatably fitted, and the sleeve 2 has a herringbone-shaped shallow groove 14 carved in the rotation @I for forming a hydrodynamic radial bearing and a hydrodynamic thrust bearing. A recess 16 is provided at a position corresponding to between the spiral shallow grooves 15 through which lubricating fluid flows. A plurality of protruding members are attached to the rotating shaft 1 between the shallow grooves 14 and 15 via elastic bodies or spring-like members 18. As shown in FIG. 2, the outer diameter of the protruding member 19 is smaller than the inner diameter d of the recess 16 when no load is applied to the spring-like member 18 and when centrifugal force due to rotation is applied. , is larger than the inner diameter Sd of the sleeve 2.

Furthermore, by applying a force in the radial direction to the protruding member 19,
The outer diameter equivalent amount D' is compressed by the spring-like member 18 and is configured to be smaller than the sleeve inner diameter d. Furthermore, the wall thickness T of the protruding member 19 is smaller than the axial length of the recess 16. Since the protruding member 19 is attached to the rotating shaft, it is desirable to attach a plurality of protruding members 19 to prevent dynamic imbalance. Therefore, in the case of assembly, the thrust plate 3 is fixed to the sleeve 2 via the fixing plate 4, and a certain amount of lubricating oil is injected into the bottom of the sleeve 2, and the holes 12, grooves 13, etc. provided in the thrust plate 3 are filled with a certain amount of lubricating oil. After performing defoaming to remove intervening air bubbles, the rotating shaft 1 is inserted. When the rotary shaft 1 is inserted, the protruding member 19 compresses the spring-like member 18 at the opening of the sleeve 2, and is released when it reaches the recess 16. In this unassembled state, even if a force is applied to the rotating shaft 1 in the direction of pulling it out from the sleeve 2, the rotating shaft may be lifted up more than necessary, causing air to be drawn into the lubricating oil, or the rotating shaft There is no fear that it will be pulled out of the sleeve. Furthermore, during rotation, since the outer diameter and wall thickness T of the protruding member 19 are smaller than the inner diameter d of the recess 16 and the axial length of the recess, it is possible to rotate without contact. A stable hydrodynamic bearing rotating device can be obtained.

In the above description, the protruding member 19 was provided at the same position as the recess for ensuring the stability of the lubricating fluid. A similar effect can be achieved by providing a protruding member 19 and a spring-like member 18.

In the above explanation, the case of shaft rotation was explained, but the same effect can be obtained in the case of sleeve rotation, and in this case, the influence of the protruding member on the dynamic imbalance during rotation is Because it disappears, the protruding member is 1
Just ke is enough.

FIG. 3 is a diagram showing another embodiment of the present invention.

A recess 20 is provided in the radial surface of the rotating shaft 1 near the end on the thrust bearing side (lower side in the figure).

A hole 2 is provided at a position opposite to the recess 20 of the sleeve 2.
1 is provided, and a protrusion and soil member 22 that fits into the hole 21 without contacting the recess 20 is attached. still,
Auxiliary holes 23 and 24 are provided in the outer cylinder 5 so that the protruding member 22 is inserted at the final point in the assembly process. In addition, since the recess 20 is provided on the closed side of the sleeve 2, when the rotating shaft 1 is inserted into the sleeve 2 or when the lubricating oil is defoamed, the lubricating oil can be passed through the hole 21 provided in the sleeve 2. may leak out. therefore,
It is desirable to attach the protruding member 22 to the hole 21 in advance to such an extent that it does not protrude from the inner peripheral surface of the sleeve 2. Furthermore, if a liquid sealing material or the like is applied to the outer peripheral surface of the sleeve of the protruding member 22 in this state, leakage of lubricating oil can be reliably prevented.

In the above explanation, the case where the recess 20 of the rotating shaft 1 is provided near the end on the thrust bearing side is explained, but the recess 20
The location where it is provided is arbitrary, and the effect is the same.

In the above description, the case of shaft rotation has been explained, but the same effect can be obtained also in the case of sleeve rotation. In this case, it is desirable to provide a plurality of protruding members because dynamic imbalance may occur during rotation.

FIG. 4 is a diagram showing another embodiment of the present invention.

A hole 25 is provided in the rotating shaft 1 from above in the axial direction until it reaches the protruding member 19. A shaft member 26 having a tapered tip is fitted into the hole 25. Also,
A tapered member 27 is attached to the protruding member 19 via a spring member 18 so as to engage with the tapered portion at the tip of the shaft member 26 . When the shaft member 26 is pushed in here, the protrusion member 19 protrudes and is fitted into the recess 16 without contact. On the other hand, when the shaft member 26 is lifted upward, the protruding member 19 will be retracted by the compression of the spring. Therefore, since the protruding member 19 can be taken in and out by taking the shaft member 26 in and out, the protruding member can be used as needed. If the shaft member 26 is connected to the rotating shaft 1 with a screw 28, it can be easily taken in and taken out, and it can be easily fixed. Note that it can be used even if the spring member 18 is removed, and the effects of the present invention will not be impaired.

[Effects of the Invention] As explained above, by providing a recess in one of the mating surfaces of the shaft and sleeve in a hydrodynamic bearing, and attaching a member that fits into the recess without contacting the other to the other, the rotating body can be rotated. It is possible to prevent the bearing from being lifted up or pulled out of the fixed member more than necessary, and it is easy to handle it as a hydrodynamic bearing after assembly is completed.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of one embodiment of the present invention, Fig. 2 is a partial detailed view for explaining the dimensional relationship in the present invention, Fig. 3 is a cross-sectional view of another embodiment of the present invention, 'tS4 figure 5 is a configuration diagram of a main part of still another embodiment of the present invention, and FIG. 5 is a sectional view of a conventional hydrodynamic bearing rotating device. 1: rotating shaft, 2 sleeve, 16.20: recess, 19: protruding member. Patent applicant Canon Co., Ltd.

Claims (2)

[Claims] (1) A shaft and a sleeve are provided that are rotatably fitted to each other, a dynamic pressure generating groove is provided on the fitting surface of at least one of the shaft and the sleeve, a recess is provided on one side of the shaft and the sleeve, and A hydrodynamic bearing rotating device characterized in that a protrusion member having a shape that can be fitted into the recess in a non-contact manner is provided on the other side. (2) The hydrodynamic bearing rotation device according to claim 1, wherein the protruding member is attached to the shaft or the sleeve via elastic means.