JPS60219953A - Motor - Google Patents

Abstract

PURPOSE:To prevent an attracting force between a stator and a rotor from operating on a spherical bearing for supporting a rotational shaft and to obtain a motor having small size and high reliability by supporting the attracting force by a thrust bearing, and applying a pressure to the bearing by a spring. CONSTITUTION:In a motor in which a start formed by mounting a coil 7 on a stator yoke 6 and a rotor formed by mounting a permanent magnet 8 on a rotor yoke 9 are planely oppositely disposed, a rotational shaft 1 is supported by two or more bearings 2, 20, and at least one uses a spherical bearing 20. Further, a thrust bearing 3 for supporting an attracting force F operated between the stator and the rotor is provided, and a spring 22 is provided to apply a pressure to the bearing 20. Thus, since the force F is not operated on the bearing 20, the bearing may be of small size, and a damage due to an impact can be eliminated.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a motor, particularly a bearing structure thereof, and particularly,
The present invention relates to a bearing structure suitable for a motor that receives large side pressure due to pinch pressure from a capstan or the like.

[Prior art]

Conventionally, this type of capstan direct drive (DD
1(a) or 1(b), the vertical cross-section of which is shown in FIG. That is, in the example shown in FIG. 1(a), the rotating shaft 1 is supported by two flat bearings 2, and the attractive force between the disc-shaped permanent magnet 8, which is magnetized with one multipole, and the stator yoke 6 is expressed as follows. A thrust bearing 3 supports the tip of the shaft 1 in a spherical shape. 5 is
This is an adjustment screw for adjusting the height of the thrust bearing 3. In the motor section, a magnet 8 is fixed to a rotor yoke 9 and fixed to the shaft 1 via a pedestal 10, and a stator yoke 6 that forms a magnetic path is fixed to the housing 4 in opposition to the magnet 8. Further, a plurality of motor coils 7 such as flat spiral coils are fixed on the stator yoke G so as to face the magnets 8.

In the example shown in FIG. 1(b), two ball bearings 11.12 are used, and the suction force F is received by the lower ball bearing 11. Here, the upper ball bearing 12 is connected to the preload table 1
3, and the lower ball bearing 11 is preloaded by suction force F through the protrusion of the pedestal 10 fixed to the rotating shaft 1.

However, in the case of FIG. 1(,), since the shaft 1 is supported by a flat bearing 2, when a pinch roller or the like presses against the shaft 1, a large load is generated and the torque loss becomes extremely large. For example, the pinch ruler has a crimping force of IK9 and a shaft diameter of 3mm.
If it is about φ, the loss torque for this is 20 to 31N.
'-an, and the actual tape drive load is 1Of-cm.
However, most of it will be lost as a loss.

In addition, in the case of Fig. 1(b), since the shaft 1 is supported by ball bearings 12. 1! M'-era
Although it can be kept to a fairly low level, the suction force F
Since this is supported by the ball bearing 11, the size of the bearing 11 becomes large, and the inner diameter of the motor coil 7 becomes large, which is not suitable for downsizing the motor. Furthermore, when assembling, the magnet 8
Since the suction force of 1 is directly applied in the thrust direction, the bearing may be damaged due to impact etc. 1 is originally designed to withstand mainly radial loads, so in this state the thrust force 1 to 2
VTRs and the like require durability of several thousand hours when changes in Kg and lateral pressure (radial load) IKf are applied, requiring fairly large bearings.

〔the purpose〕

The present invention has been made in view of the above-mentioned problems, and uses a ball bearing as a part of the bearing of the motor rotating shaft, and is configured so that it does not receive the thrust direction suction force, Moreover, by configuring the bearing mechanism so that an appropriate preload can be applied, the present invention aims to provide a small, highly reliable, and low-cost motor.

〔Example〕

The present invention will be explained below based on the drawings. FIG. 2 is a structural vertical cross-sectional view showing one embodiment of the present invention, which is the same as FIG. 1 (
The rotating shaft 1 is supported by an upper plain bearing 2 and a lower ball bearing 20, and a thrust direction acting between a stator yoke 6 and a magnet 8 is used. The suction force F is configured to be received by the thrust bearing 3. The inner ring of the ball bearing 20 has a preload stand 2.
1 and the pedestal 10, a preload spring 22 such as a compression coil spring is installed.
Provide preload by interposing. For other configurations, see Figure 1 (
Since this is the same as that shown in a), further explanation will be omitted.

By configuring as above, the suction force F is transferred to the ball bearing 2.
Since there is no direct load on the ball bearing 20, the durability and reliability of the ball bearing 20 are greatly improved.

Further, since a constant preload is always applied to the ball bearing 20 by the preload spring 22, there is no play during the pinch roller crimping, and there is no play in the ball bearing, so there is no damage due to this. Further, the rotational shaft runout due to the above-mentioned play is prevented. Furthermore, during assembly, the attractive force F of the magnet 8 is not directly applied suddenly to the ball bearing 20, so the IGT properties are greatly improved and defects are less likely to occur. In addition, since the suction force F is not directly applied, the preload force can be less than 1/work 0 compared to the case shown in Fig. 1(b), for example, and therefore the ball bearing itself can be made smaller in size. This makes it possible to reduce the inner diameter of the motor coil 7, thereby making it possible to reduce the size of the motor and the DD capstan motor itself.

Furthermore, when applying the preload, conventionally the ball bearing 20
This was expensive because it was necessary to select a highly accurate one with a small gap, but in the present invention, a wide tolerance for accuracy can be selected, making it possible to construct it at an extremely low cost.

In addition, since a ball bearing can be used on one side of the bearing, the loss torque of shaft 1 when the pinch roller is crimped can be calculated as shown in Figure 1 (IL).
Since the torque capacity of the motor itself is small, it is possible to reduce the size of the motor, and as a result, it is possible to provide a motor that is generally inexpensive.

[Other Examples]

1) Second Embodiment Figure 3 is a longitudinal sectional view of an embodiment in which a ball bearing 24 is used as the upper bearing. By using a ball bearing on the side that bears the load, the effect of reducing the torque loss is further enhanced. That is, the rotating shaft 1 is
It is supported by an upper ball bearing 24 and a lower flat bearing 23, and the thrust flat bearing 3 receives the suction force F in the thrust direction.

The preload on the ball bearing 24 is applied to the preload spring 26 on the ball bearing 24.
The inner ring is configured such that an annular stopper 25 is press-fitted and fixed to the shaft 1, and a preload is applied by a spring force.

2) For each of the lower/upper bearings in the third embodiment and above, please refer to Fig. 2/
It is clear that if the ball bearing portion is configured as explained in the first and second embodiments of No. 3I211, ball bearings can be used for both the lower and upper bearings.

Further, the thrust plain bearing can use a synthetic resin plate such as polyacetal resin, for example. Also, if the lateral pressure load is small, it can also be used for flat bearings.

3) Fourth Embodiment FIG. 4 is a longitudinal sectional view showing a bearing mechanism in which the rotating shaft 1 is supported in a cantilevered manner. In this embodiment, when the side pressure of the pinch roller is applied to the rotary shaft 1, a large two-dimensional ball bearing 39 is used, and a flat bearing 40 is used as the lower bearing. 37 is a stopper press-fitted into the shaft 1, and the preload spring 3
8 applies a preload to the inner ring of the ball bearing 39. 35
31 is a thrust flat bearing, 31 is a bearing housing, 32 is a housing plate integrated with this, and the stator yoke 6 is fixed to the plate 32 via a spacer 33.

In each of the embodiments shown in FIGS. 2 to 4 above, the direction of the preload force applied to the rotating shaft and the direction of the thrust suction force F are opposite directions, so that they cancel each other out. Therefore, the force applied to the thrust bearing is actually reduced by the preload force, which is also effective in improving the durability of the thrust bearing.

In the configurations shown in FIGS. 2 to 4, the configuration of the bearing mechanism shown in FIGS. 2 to 4 is also possible with a brushed surface facing motor that supplies power to the motor coil A/7 of the rotor yoke 9 through a brush.

Each of the embodiments of the present invention is particularly effective for capstan DD motors of VTRs, etc., but is not limited to this, and can of course be applied to other similar motor structures. [Effect] As explained above, according to the present invention, by receiving the attractive force between the magnetic yoke and the magnet in which the coil is disposed by another thrust bearing, the above-mentioned attractive force against the ball bearing is reduced. The effect is reduced, and by applying preload to the ball bearing using a rough preload spring, the ball bearing can be made small in size, and there is no longer a need for high precision as in the past. Also, during assembly,
Since the suction force does not impact the bearing, damage to the bearing can be prevented and reliability can be improved. In addition, since torque loss on the shaft due to lateral pressure load is significantly reduced, it is possible to comprehensively downsize the motor and improve its rotational characteristics.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are longitudinal cross-sectional views showing two examples of a conventional capstan DD motor bearing mechanism, and FIG.
3, and 4 are longitudinal cross-sectional views of bearing structures showing three embodiments of the present invention, respectively. 1...Rotating shaft 2.23.40...Flat bearing 3.35...Thrust plain bearing 4...Housing 6, 6'・・・：・Stator yoke coil 7.7'
, 34... Coil 8.8', 32... Permanent magnet 9.9'... Rotor yoke 10... Pedestal 11.12, 20, 24 .39...Ball bearing 22
．． 26.38...Preload spring F...
·Suction power

Claims (1)

[Claims] A multi-pole magnetized disc-shaped permanent magnet, a magnetic yoke opposing the magnetic yoke forming a magnetic circuit, a coil disposed on the yoke to face the magnet, and a magnetic yoke formed between the magnet and the yoke. In a motor having a rotary shaft, one of which is taken out, the rotary shaft is supported by at least two bearings,
The attractive force acting between the magnet and the stator yoke is
1. A motor, characterized in that the motor is supported by a separate thrust bearing, at least one of the two bearings is a ball bearing, and a preload is applied to the ball bearing by a spring.