JPH033627A - Bearing structure of motor - Google Patents

Abstract

PURPOSE:To prevent the movement of a shaft by thrust by imposing thrust load until a curved preloading flat spring for position regulation assembled to the outside end face of a bearing inserted by a shaft will be of a flat washer. CONSTITUTION:A shaft 2 of a rotor 8 is inserted into ball bearings 5A and 5B and rotatably supported to a housing 1. A bush 7 is interposed between the casing of the rotor 8 and the ball bearing 5B for positioning. After a curved flat spring 6 having a hole into which the shaft 2 is inserted was interposed between the ball bearing 5A and a turntable 3a, the turntable 3a is fastened tightly to make the flat spring 6 flat-washerwise. The figure shows the condition after the turntable 3a was fastened. The movement of the shaft by the fluctua tion of thrust load can thereby be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing structure for a motor having a structure in which a shaft is inserted through two bearings arranged coaxially at a predetermined interval.

[Conventional technology]

FIGS. 3 and 4 are longitudinal cross-sectional views illustrating the bearing structure of a conventional motor having the above structure, respectively.

These motors have a structure suitable for use as, for example, an optical spindle motor.

In FIG. 3, 1 is a motor housing, and two bearings 5A and 5B are held at a predetermined interval on the inner diameter of the motor housing, and the shaft is inserted into the center hole of the bearing formed by these bearings 5A and 5B. 2 is rotatably supported.

The shaft 2 is for centering a carrier (not shown) such as an optical mezzo ear, and a turntable 3 for holding and rotating the optical mezzo ear is fitted and fixed to the upper part of the shaft 2.

7 is a bushing which is fixed to the shaft 2 by adhesive or the like after being fitted into the shaft 2 and positioned.

By fixing this bushing 7, pressure (preload) is applied between the turntable 3 and the bushing 7 to push the two bearings 5A and 5B inward.

In a state where such preload is applied, the bearing 5
Since the inner race, outer race, and bearing balls of A and 5B are biased in one direction, a bearing without backlash can be constructed.

As mentioned above, the method of enclosing preload in the bearings 5A, 5B by regulating their positions is referred to as fixed position preload within the membrane.

A rotor 8 is fixed to the bush 7 with screws 10, and a magnet 9 is fixed to the inside of the rotor 8.

The end face of the motor housing 1 includes a coil wiring PCB 12 to which the coil 11 is fixed, and a coil wiring PCB 12 to which the coil 11 is fixed.
A stator yoke to which B 12 is adhered to form a magnetic circuit is fixed with screws 14.

The coil 11 and the magnet 9 are arranged to face each other.

When the coil 11 is energized, due to the well-known electromagnetic effect,
The magnet 9 receives the rotational force, and the rotational force is transmitted to the rotor 8, the bush 7, the shaft 2, and the turntable 3, and a carrier (not shown) such as an optical mesoyer is driven.

In FIG. 4 showing another example of conventional shaft construction, one bearing 5B and the convex stepped portion 1b of the motor housing 1 are
A preload spring 15 is installed between the two.

Between the inner races of the two bearings 5A and 5B,
Collar 16 is attached.

Therefore, by fitting the bushing 7 onto the shaft 2 and fixing the bushing 7 with adhesive or the like so that the bearing 5A, collar 16, and bearing 5B are in contact with the turntable 3, the action of the preload spring 15 bearing 5
The outer race B is pressed and the looseness of the bearings 5A and 5B can be removed.

Although the bearing structure in Fig. 4 differs from the structure in Fig. 3 in the points explained above, it has the same structure in other parts, and corresponding parts are indicated with the same numbers and details thereof. The explanation will be omitted.

In the conventional bearing structure shown in FIG. 4, play in the bearings 5A and 5B is removed by a preload spring 15, and such a system is called a constant pressure preload type.

[Technical problem to be solved by the invention] However, in the fixed position preload type bearing structure shown in Fig. 3, play is likely to occur when the preload is released due to thermal expansion of the motor housing 1 or wear of the bearings 5A and 5B. There was a tendency.

In other words, as seen in the graph of Fig. 12, the thrust displacement amount δ relative to the thrust load P of the bearing is only a few microns, so when thermal expansion or wear occurs, the preload amount can be quickly handled, causing play. There was a tendency for this to occur.

On the other hand, in the constant pressure preload type bearing structure shown in FIG. 4, since the outer race of the bearing 5B and the motor housing 1 are fitted with a clearance, the bearing 5B is likely to be misaligned.

For this reason, in high-precision motors, the bearing 5B is sometimes bonded to the motor housing 1, but in that case, preload loss is likely to occur as in the fixed position preload type shown in FIG.

Further, if the above-mentioned bonding is not performed in the structure shown in FIG. 4, the rigidity of the bearing will be reduced.

The present invention has been made in view of the above-mentioned conventional technical difficulties, and an object of the present invention is to provide a bearing structure for a motor that can prevent preload loss with a simple structure and whose position in the height direction does not change even under thrust loads. With the goal.

(Means for Solving the Problems) The present invention provides a fixed position preload type in which a shaft is inserted into two bearings arranged coaxially with a predetermined interval, and the outer end surfaces of the two bearings are assembled by regulating their positions. In this motor bearing structure, a curved leaf spring is fitted onto the shaft, a thrust is applied until the leaf spring becomes like a flat washer, and the assembly is assembled so that it hardly moves even under the thrust load, thereby achieving the above purpose. The goal is to achieve the following.

[Effect]

According to the above configuration, a preload spring (curved temporary spring) is installed between the turntable 3 and the bearing 5A while adopting the same structure as shown in FIG. By setting it so that, when the preload is not released, it becomes a fixed position preload type, and when the preload is released, the leaf spring is displaced (usually several microns) to maintain the spring preload.

That is, as seen in the graph of FIG. 11, a spring characteristic with a substantially constant slope is obtained within the range of the compressed length (axial displacement) of the temporary spring, so that a predetermined preload can be maintained.

Further, since the leaf spring is shaped like a flat washer, even if a load is applied to the turntable 3 from above, the position in the height direction does not change.

Furthermore, the rigidity can be maintained at a high level, unlike the normal spring preload type.

〔Example〕

The present invention will be specifically described below with reference to FIGS. 1, 2, and 5 to 10.

FIG. 1 is a longitudinal sectional view of a motor equipped with a bearing structure according to an embodiment of the present invention, and FIG. 2 is a plan view of FIG. 1.

This embodiment shows a case where the present invention is applied to an optical spindle motor.

In FIG. 1, ■ is a motor housing, and two bearings 5A are coaxially mounted at a predetermined distance on the inner diameter of the motor housing.
5B is held and constitutes a bearing that supports the shaft 2.

The shaft 2 is for centering an optical mezzo ear (not shown), and a turntable 3 for holding and rotating the optical mezzo ear is fixed to a protrusion of the shaft 2.

Reference numeral 4 denotes an adsorption magnet fixed on the turntable 3, which magnetically attracts an adsorption plate of an optical mesoyer (not shown) and brings it into pressure contact with the protruding surface 3a of the turntable 3, thereby imparting a rotational driving force to the optical mezzoyer. It is for communicating.

A preload spring 6 is held between the inner race of the bearing 5A and the turntable 3, and is formed of a curved plate spring as shown in FIG.

Reference numeral 7 denotes a bushing that is loosely fitted (gap fit) onto the shaft 2. By incorporating the bushing 7, preload is applied to each bearing 5A, 5B between the bushing 7 and the turntable 3, and then the bushing 7 is fitted onto the shaft 2. It is fixed with adhesive.

FIG. 6 shows the cross-sectional shape of the preload spring 6 before it is assembled, and FIG. 7 shows the cross-sectional shape when the preload spring 6 is assembled and crushed by a flat washer.

8 is a rotor, and a magnet 9 is fixed to the inside thereof.

The rotor 8 with the magnet 9 is fixed to the bush 7 with a screw 10.

Reference numeral 11 indicates a coil, 12 a PCB (printed circuit board) for coil wiring, and 13 a stator yoke constituting a magnetic circuit.

The coil 11 is fixed to the PCBI 2 for coil wiring, and the PCB 42 for coil wiring and the stator yoke 13 are fixed to the end surface of the motor housing 1 with screws 14.

In this way, a motor is constructed in which the rotor 8.9 and the stator 11, 12, 13 are arranged face to face with each other.

Note that the motor housing 1 is formed with a hole 1a for fixing the motor.

Further, 1b is a convex stepped portion for positioning and fixing the outer races of the bearings 5A, 5B within the motor housing 1.

FIG. 8 is a perspective view showing another form of the preload spring 6, FIG. 9 is a plan view of FIG. 8, and FIG. 10 is a sectional view of FIG. 8.

In FIGS. 8 to 1O, the preload spring 6 in this case is
Multiple (4 locations) protrusions 21 on the inner diameter of the curved washer
It has a structure in which a relief 22 is formed between the two.

In the case of the washer 6 without the relief 22 shown in FIGS. 5 to 7, if a preload is applied to the curved washer 6 and the curvature is changed from 800 microns before curvature to 80 microns before being assembled, the external force will be reduced. As a result, the degree of curvature reaches 800 microfron or more, and when approaching the flat washer, the part near the inner diameter does not become flat, which causes an error in height when an external force is applied, causing an error in the focus of the optical pickup. Something happened.

By providing the relief 22 as shown in FIGS. 8 to 10, the above-mentioned problems can be solved, and even when external force is applied,
It became possible to easily maintain the flatness of the washer 6.

According to the embodiment described above, the two hair rings 5A and 5B are coaxially arranged at a predetermined distance in the motor housing 1.
In the bearing structure in which the shaft 2 is inserted into the bearings 5A and 5B, the basic structure is a fixed position preload type, and the inner race of each bearing 5A and 5B is preloaded between the turntable 3 and the bearing 5A. The preload spring 6, which is a curved temporary spring, is inserted into the aluminum alloy in a compressed state (like a flat washer) at a position where it can provide constant pressure preload function even if wear or thermal expansion occurs. Thus, a motor bearing structure that can effectively prevent preload loss has been obtained.

Furthermore, since the preload spring 6 is incorporated in the form of a flat washer, even when a force in the thrust direction is applied to the turntable 3, such as when assembling a carrier such as an optical mesoyer, there is no change in the position in the height direction. We were able to maintain high accuracy.

Furthermore, we were able to secure the same level of rigidity as a fixed position preload type bearing.

In addition, in FIG. 1, the leaf spring (preload spring) 6 is
It may also be installed between the bearing 5B and the bushing 7 (position 7a); similar effects could also be achieved with such a structure.

In particular, in the case of a motor in which the attracting force of the rotor 8 in the direction of the arrow F is weak, such as a circumferentially facing type motor, rather than the surface facing type shown in the figure, it is preferable that the leaf spring 6 is installed between the bearing 5B and the pusher. .

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a shaft is inserted into two bearings coaxially arranged at a predetermined interval, and the outer end surfaces of the two bearings are positioned and assembled. In the bearing structure of a position preload type motor, a curved leaf spring is fitted onto the shaft, a thrust is applied until the leaf spring becomes like a flat washer, and the assembly is assembled in a state where it hardly moves even under the thrust load. Therefore, there is provided a bearing structure for a motor that can prevent loss of preload in the thrust direction and also prevent a change in position in the axial direction even if a force in the thrust direction is applied.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view showing a bearing structure of a motor according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a schematic diagram showing an example of a conventional motor bearing structure. longitudinal section,
Fig. 4 is a schematic vertical cross-sectional view showing another example of a conventional motor bearing structure, Fig. 5 is a perspective view of the temporary spring for preload shown in Fig. 1, and Fig. 6 is the temporary spring shown in Fig. 5. Sectional view before installation, No. 7
The figure is a sectional view of the plate spring shown in Fig. 5 when it is assembled, Fig. 8 is a perspective view showing another example of the temporary spring for preload, and Fig. 9 is a sectional view of the plate spring shown in Fig. 8.
10 is a sectional view of FIG. 8, FIG. 11 is a graph illustrating the relationship between the spring load and pressure 11t of the temporary springs of FIGS. 5 and 8, and FIG. 12 is a graph of the bearing. It is a graph which illustrates the relationship between thrust load and thrust displacement amount. 1.--Motor housing, 2-1111.-Shaft, 3.--1-.Turntable, 5 A, 5
B---1・-Bearing, 6・・・・・・・Plate spring (
Preload spring), 7---Bush, 8---Rotor, 11-1---Coil, 13---Stator yoke. (7884) Patent Attorney Yasutake Oon Figure 3 Figure 4

Claims (1)

[Claims] (1) In a fixed position preload type motor bearing structure in which a shaft is inserted through two bearings coaxially arranged at a predetermined interval, and the outer end surfaces of the two bearings are positioned and assembled, the shaft 1. A bearing structure for a motor, characterized in that a curved plate spring is fitted into the plate spring, a thrust is applied to the plate spring until it becomes flat washer-like, and the plate spring is assembled in such a state that it hardly moves even under a thrust load.