JP3232994B2 - Motor thrust bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust bearing for a motor used in video and audio equipment such as a video tape recorder (hereinafter, referred to as VTR) and an audio cassette tape recorder.

[0002]

2. Description of the Related Art In recent years, in audiovisual equipment such as VTRs, higher performance, smaller size, lighter weight, and lower cost have been demanded, and the capstan motor for transporting the tapes of the components has been similarly required. There is a demand for higher performance, smaller size, lighter weight, and lower cost.

A conventional motor thrust bearing will be described below. A conventional motor thrust bearing is disclosed in Japanese Utility Model Publication No. 6-40444. FIG. 10 is a longitudinal sectional view of the motor in the publication, and FIG.
1 is a plan view of a main part showing a relationship between a shaft and a hook in the publication, and FIG. 12 is an enlarged view of a portion A in FIG. FIG.
At 0, a boss 3 having a rotor yoke 2 fixed to the outer periphery is fitted to the base end of the shaft 1 of the motor. The rotor yoke 2 is formed in a substantially cup shape, and a substantially cylindrical rotor magnet 4 is disposed on the inner peripheral surface. Further, the stator core 6 has a center hole fitted and fixed to the peripheral surface of the bearing holder 7, and the rotor magnet 4 is opposed to the outer peripheral surface where the winding 5 is applied to each salient pole (not shown). The bearing holder 7 is formed in a substantially cylindrical shape, and bearings 8 such as an oil-impregnated metal are provided inside the both ends, respectively, and the shaft 1 is rotatably supported in an inner hole of the bearing 8. A neck portion 7a is integrally formed on the outer periphery of the bearing holder 7, and a substrate 9 made of, for example, a circuit substrate constituting a control and drive circuit is attached to the neck portion 7a. On the output side of the shaft 1 located near the bearing 8, an annular groove 1a (FIG. 12) is engraved.
An E-ring 20 as a hook is fitted in a.
A pair of thrust bearings 21 and 22 are interposed between the E-ring 20 and the upper end surface of one bearing 8. Among the thrust receivers, the thrust receiver 21 disposed on the E-ring 20 side is made of, for example, nylon, Teflon, or another resin having relatively little friction or wear, or a metal body coated with a resin for low friction, As shown in FIG. 11, a projection 21a is integrally provided from one end face.
The projection 21a enters a notch for insertion of the E-ring 20, and is rotated integrally with the E-ring 20 and the shaft 1. On the other hand, the thrust receiver 22 is the thrust receiver 2
1 is formed in a substantially donut shape by the same member, and abuts against the upper end surface of the bearing 8 and the outer peripheral edge abuts on the inside of the end surface of the bearing holder 7. A pair of thrust bearings 2 is provided between the rotating E-ring 20 and the fixed bearing 8.
By interposing the shafts 1 and 22, the thrust bearing 21 on the shaft 1 side and the thrust bearing 22 on the bearing 8 are connected to each other and slide, so that the shaft 1 is prevented from moving downward in the figure. A groove 3a is formed in the outer periphery of the boss 3, and a belt (not shown) for driving a reel base or the like to rotate is suspended in the groove 3a.

[0004]

However, the above-described conventional configuration has the following problems.

(1) The mounting operation itself is not easy because the E-ring must be inserted into the groove in the direction perpendicular to the longitudinal direction of the shaft. (2) In the direction perpendicular to the longitudinal direction of the shaft. Since the E-ring is inserted, lateral pressure is applied to the shaft, which causes a problem of shaft deflection. (3) The E-ring 20 and the thrust receiver 21 need to be phase-aligned at the time of insertion, and the assembly workability is good. Absent. Therefore, there is a problem that the processing cost at the time of assembly is high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-cost motor thrust bearing which solves the above-mentioned conventional problems, reduces the number of parts, and improves assembly workability.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides an engaging portion for press-fitting a shaft into a shaft and integrally rotating the shaft and a groove for locking the shaft in a longitudinal direction. In this case, a protrusion for preventing the rotation and a sliding portion that comes into contact with the fixed-side thrust bearing are integrally formed on the rotation-side thrust bearing. This not only reduces the number of components of the thrust bearing, but also prevents the shaft from coming off due to an impact load.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a housing in which a radial bearing impregnated with oil is disposed and a rotor having permanent magnets magnetized to a plurality of poles are fixed. A shaft formed in an annular groove in the circumferential direction and rotatably supported by the radial bearing; and a fixed-side thrust fixed to an end surface of the housing and opposite to the rotor. A bearing, an engaging portion for press-fitting into the shaft and integrally rotating, a projection for locking in the groove to prevent the shaft from moving in the longitudinal direction, and a fixed-side thrust bearing. A rotating-side thrust bearing made of a resin material integrally formed with a contacting sliding portion , wherein the protrusion is spaced from the shaft.
The shaft, the radial bearing, the how
Jing, the fixed-side thrust bearing, and the rotating-side thrust bearing.
The gap is sealed by a strike bearing.
That a thrust bearing of the motor, at the same time the rotation-side thrust bearing and rotation of the rotor rotates, slides between the fixed-side thrust bearing and the sliding portion. Also, when an impact load is applied to the shaft in the longitudinal direction of the shaft to the rotor, the shaft is restricted from moving because the groove is locked to the protrusion. Further, the engaging portion is press-fitted.
Lubricating oil impregnated in the radial bearing
It also has the effect of preventing it from flowing to the side.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a longitudinal sectional view of a capstan motor of the present invention, and FIG. 2 is a longitudinal sectional view of a main part of a thrust bearing portion. In FIG. 1, a rotor yoke 2 made of a magnetic material is fixed to a base end of a capstan shaft 1 by means such as press fitting. The rotor yoke 2 is formed in a substantially cup shape, and a substantially cylindrical rotor magnet 3 which is magnetized to a plurality of poles in a circumferential direction is disposed on an inner peripheral surface. The capstan shaft 1, the rotor yoke 2, and the rotor magnet 3 form a rotor 18 of the capstan motor. In order to detect the number of rotations of the rotor 18 of the capstan motor, a rotating part 4 of a frequency generator composed of a plurality of FG magnets that are magnetized in plural poles is integrally held on the outer periphery of the rotor 18. At a position facing the rotating section 4 of the frequency generator, a rotational speed detecting element 19 including a ring head, a magnetoresistive element, and the like is provided. The output of the rotation speed detecting element 19 is connected to a control circuit (not shown) for controlling the rotation speed of the rotor 18 to be constant via a substrate 14 described later. Further, the rotor magnet 3 is opposed to an outer peripheral surface of a stator core 6 having a plurality of exciting windings 5 on salient poles (not shown) through a predetermined gap. In order to transmit the rotation of the rotor 18 of the capstan motor to the outside, a pulley 9 is fixed to the rotor yoke 2 by means of press fitting, bonding or the like. A belt 13 for rotating and driving a reel base (not shown) and the like is suspended from the pulley 9. The housing 7 is formed in a substantially cylindrical shape, and radial bearings 8 made of oil-impregnated metal or the like are disposed inside the both ends, respectively.
Has been concluded. An annular groove 1 a is formed in the capstan shaft 1 near the radial bearing 8 and on the output side opposite to the rotor yoke 2 with respect to the housing 7. A terminal holder 11 is fixed to the stator core 6, and an end of the exciting winding 5 is soldered to a terminal 12 provided on the terminal holder 11. A board 14 composed of a circuit board or the like constituting the drive circuit 15 is fixed to the terminal holder 11, and the excitation winding 5 is electrically connected to the drive circuit 15 via the terminal 12. A plurality of rotor position detecting elements 20 such as Hall ICs for detecting the position of the rotor magnet 3 are also mounted on the substrate 14. Stator core 6
Is fitted and fixed to the peripheral surface of the housing 7.
An engaging portion 16a (FIG. 2) of a rotary thrust bearing 16 made of a resin material having high slidability is press-fitted in the vicinity of the groove portion 1a, and is rotatable integrally with the capstan shaft 1. A protrusion 16b is provided in a predetermined area on the inner peripheral surface of the rotation-side thrust bearing 16, and is engaged with the groove 1a to prevent the capstan shaft 1 from moving in the longitudinal direction. In other words, the rotating-side thrust bearing 16 integrally forms the engaging portion 16a, the protrusion 16b, and the sliding portion 16c that comes into contact with the fixed-side thrust bearing 17 described later. Further, the fixed-side thrust bearing 17 is made of a resin or a metal material having high slidability, is fixed to the end face of the housing 7, and is in contact with the sliding portion 16c of the rotating-side thrust bearing 16 (see FIG. 2). . At the time of assembling, the engaging portion 16a and the projection 16b of the rotating-side thrust bearing 16 are inserted in the longitudinal direction from the tip of the capstan shaft 1 while being elastically deformed.
When the assembly is completed, the protrusion 16b returns to the initial state without deformation, and the engaging portion 16a maintains the elastic deformation state.

The operation of the motor thrust bearing configured as described above will be described. First, since the rotor position detection element 20 detects the rotation position of the rotor 18 by detecting the magnetic pole of the rotor magnet 3,
When a current is switched and supplied to each phase of the excitation windings 5 of a plurality of phases in accordance with this output signal, the rotor 18 starts rotating by the action of the magnetic force generated by the excitation windings 5. When the rotor 18 rotates, the rotation speed detecting element 19 generates a signal pulse due to a change in magnetic force generated by the rotating unit 4 of the frequency generator. The number of rotations of the rotor 18 is detected by counting the number of pulses. As a result, the rotation speed of the rotor 18 can be controlled to be constant by a control circuit (not shown) based on the output signal of the rotation speed detection element 19. The pulley 9 rotates with the rotation of the rotor 18, and power is transmitted to the outside of the capstan motor by the belt 13 suspended on the pulley 9. When a pinch roller (not shown) is in pressure contact with the capstan shaft 1 via a tape (not shown), the tape (not shown) is transferred at a constant speed as the capstan motor rotates. . Further, the rotation-side thrust bearing 16 rotates integrally with the capstan shaft 1 and slides with the fixed-side thrust bearing 17. Further, even if an impact load is applied in the longitudinal direction of the capstan shaft 1 (toward the pulley 9 with respect to the housing 7) due to a drop or the like, the protrusion 16
Since b is locked in the annular groove 1a, the relative position of the rotation-side thrust bearing 16 with respect to the capstan shaft 1 is regulated, and the movement of the capstan shaft 1 is prevented.

[0011] (Reference Example 1) Figure 3 is a fragmentary longitudinal sectional view of the thrust bearing portion of the motor in Reference Example 1 of the present invention, FIG. 4 is a plan view of a rotary thrust bearing. In FIG. 3, the rotation-side thrust bearing 16 is
As in FIG. 1, it rotates integrally with the capstan shaft 1 and slides with the fixed-side thrust bearing 17. The difference from FIG. 1 is that a plurality of (three in FIG. 4) protrusions 16b are formed in a predetermined area in the circumferential direction. Other configurations and operations are the same as those of the first embodiment, and the description is omitted.

( Embodiment 2 ) FIG. 5 is a longitudinal sectional view of a main part of a thrust bearing portion of a motor according to the present invention, and FIG. 6 is a front view of a rotary thrust bearing. FIG.
1, the rotation-side thrust bearing 16 rotates integrally with the capstan shaft 1 as in FIG. 1 and slides with the fixed-side thrust bearing 17. The difference from FIG. 1 is that a notch 16d is formed in a predetermined area of the engaging portion 16a. Also, as shown by the hatched portion in FIG.
The engaging portion 16a extends over the entire circumference even if the notch portion 16d is provided.
In this case, a part of the area to be engaged is left. This notch 1
6d is used when it is necessary to remove the capstan shaft 1 from the housing 7, and the rotating side thrust bearing 16 is broken by pushing and expanding the notch 16d in the circumferential direction with a dedicated jig or the like ( The capstan shaft 1 can be pulled out of the housing 7 (with breakage). Other configurations and operations are described in Embodiment 1.
The description is omitted because it is the same as.

[0013] (Reference Example 2) FIG. 7 is a fragmentary longitudinal sectional view of the thrust bearing portion of the motor in Reference Example 2 of the present invention, FIG 8 is a front view of the rotating thrust bearing, Figure 9 is a plan view of the same . 7, the rotation-side thrust bearing 16 is similar to the capstan shaft 1 shown in FIG.
, And slides with the fixed-side thrust bearing 17. The difference from FIG. 1 is that a cutout portion 16 e is formed in the rotation-side thrust bearing 16. The cutout portion 16e is provided with the cutout portion 16 described in the third embodiment.
Similar to d, the capstan shaft 1 is used when it is necessary to remove the capstan shaft 1 from the housing 7, and the capstan shaft 1 is removed from the housing 7 by pushing the slit 16 e in the circumferential direction with a dedicated jig or the like. Is what you can do. Other configurations and operations are the same as those of the first embodiment, and the description is omitted.

[0014]

According to the present invention, the following effects can be obtained. (1) The structure of the rotation-side thrust bearing can be simplified, so that the thrust bearing and the rotor can be used together, and the number of parts can be reduced and the cost can be reduced. (2) Since the rotating thrust bearing is inserted from the tip of the shaft and assembled, the assemblability can be improved with respect to the E-ring configuration. Further, there is no need to worry about the deflection of the shaft due to the lateral pressure, which is a problem of the E-ring configuration. Further, the phase adjustment of the rotation-side thrust bearing is unnecessary. (3) The engagement part of the rotating thrust bearing is capstan
The radial bearing is impregnated with
Lubricating oil is on the shaft end side (the opposite side of the rotor yoke
Output side). (4) By providing the notch in the rotation-side thrust bearing, the capstan shaft can be easily removed from the housing, thereby improving serviceability.

As described above, it is possible to realize a low-cost motor thrust bearing which has a simple structure and also serves to prevent the rotor from coming off.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a capstan motor according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the thrust bearing part.

FIG. 3 is a vertical cross-sectional view of a main part of a thrust bearing portion of Reference Example 1 .

FIG. 4 is a plan view of the rotation-side thrust bearing.

[5] essential part longitudinal cross sectional view of the thrust bearing portion definitive to a second embodiment of the present invention

FIG. 6 is a front view of the rotation-side thrust bearing.

[7] essential part longitudinal cross sectional view of the thrust bearing portion definitive Reference Example 2

FIG. 8 is a front view of the rotation-side thrust bearing.

FIG. 9 is a plan view of the same.

FIG. 10 is a longitudinal sectional view of a conventional motor.

FIG. 11 is a plan view of a main part showing a relationship between a shaft and a hook of a conventional motor.

12 is an enlarged view of a portion A in FIG. 10 of a conventional motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capstan shaft 1a Groove part 2 Rotor yoke 3 Rotor magnet 4 FG magnet 5 Excitation winding 6 Stator core 7 Housing 8 Radial bearing 9 Pulley 10 Mechanical chassis 11 Terminal holder 12 Terminal 13 Belt 14 Substrate 15 Drive circuit 16 Rotating thrust bearing 16a Engagement Part 16b Projection part 16c Sliding part 16d Notch part 16e Cut part 17 Fixed-side thrust bearing 18 Rotor 19 Rotation speed detecting element 20 Rotor position detecting element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-68354 (JP, A) JP-A-2-41674 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 5/16-5/167 F16C 17/04

Claims (2)

(57) [Claims] 1. A housing in which a radial bearing impregnated with oil is disposed and a rotor having permanent magnets magnetized in a plurality of poles are fixed.
A shaft rotatably supported by the radial bearing by forming an annular groove in a circumferential direction; and a fixed-side thrust bearing fixed to an end surface of the housing and opposite to the rotor. An engagement portion for press-fitting the shaft to rotate integrally therewith; a projection for engaging the groove to prevent the shaft from moving in the longitudinal direction; A rotating-side thrust bearing made of a resin material integrally formed with a contacting sliding portion , wherein the projection has a gap between the shaft and the shaft, the shaft, the radial bearing, the housing,
For the fixed-side thrust bearing and the rotating-side thrust bearing
Therefore, a thrust bearing for a motor , wherein the gap is sealed . 2. The rotating thrust bearing according to claim 1 , wherein
In this case, the part that is in close contact with the shaft
And a cutout provided in part
Item 3. A thrust bearing for a motor according to item 1.