JP2948051B2 - Motor brake mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake mechanism for an electric motor.

[0002]

2. Description of the Related Art FIG. 8 shows a brake mechanism in an electric motor, for example, a brushless capstan motor for a VTR. In this motor, a stator set including a core winding (stator) 111 and a bearing 112 is attached to a predetermined circuit formed on a circuit board 120, and a rotor case 101, a driving magnet 102, and a cap A structure is adopted in which a rotor set including a stun shaft (rotating shaft) 103 and the like is mounted.

A driving magnet 102 constituting a rotor set
Are integrally fixed to the inner peripheral surface of the rotor case 101. The core winding set 111 is also provided inside the rotor case 101 so as to face the drive magnet 102. An electromagnetic force is generated by switching by passing a current through the coil of the core winding 111, and the rotor case 101 is continuously rotated integrally with the driving magnet 102 by repelling and attracting the driving magnet 102.

An FG is provided on the outer periphery of the rotor case 101.
(Frequency generator) A magnet 104 is provided integrally. A brake surface 105 is provided on the outer peripheral surface of the FG magnet 104. FG magnet 104
Has a configuration in which magnetized surfaces are formed at regular intervals in the outer peripheral direction. Further, an MR element 121 is provided on the circuit board 120 so as to face the FG magnet 104. The MR element 121 detects the magnetized surface of the FG magnet 104 and generates an FG signal. The motor speed is controlled by a circuit (not shown) based on the FG signal.

[0005] The VTR deck has functions such as frame advance and slow reproduction. In the brushless capstan motor having the above-described configuration, the speed of the motor at the time of an intermittent operation such as frame feed of a VTR image is performed based on the FG signal in a state where the motor is incorporated in a VTR deck.

However, the intermittent motion of the stator case in the motor control during the intermittent operation is difficult to accurately and electrically control due to the control of the motor body and the structure, and the speed control at an extremely low speed is unstable. Therefore, a mechanical brake mechanism is provided because the image may be sent too much earlier.

As this kind of brake mechanism, there is used a brake mechanism composed of a combination of the above-mentioned brake surface 105 and a brake pad operated by a brake lever (not shown) for pressing the brake surface 105. In this brake mechanism, the brake pad is pressed against the brake surface on the outer periphery of the rotor case 1 via a brake lever at an appropriate pressure by using, for example, the biasing force of a spring. A configuration for performing accurate speed control at the time of intermittent feeding is employed.

[0008]

In the above-mentioned conventional brake mechanism, the outer peripheral surface of the FG magnet provided with the brake surface cannot be made wide due to the limitation of the motor size. Therefore, a method of increasing the pressure of the brake by increasing the pressing force of the brake pad against the brake surface is usually adopted.

However, when the brake pressure is increased as described above, it is necessary to increase the component strength of the brake lever and the mechanical parts around it. For this reason, there is a problem that the cost of parts and the like is increased and the cost of the brake mechanism is increased.

Further, since the brake pressure must be increased, there is a problem that the brake surface and the brake pad are greatly deteriorated (wear), and the degree of deterioration of the brake performance after a long time use is remarkable.

Further, as the brake pressure increases, the sliding load between the motor bearing and the rotary shaft (capstan shaft) increases. Then, a high load from the side surface in a low-speed state deteriorates the sliding loss between the motor bearing and the rotating shaft, which increases power consumption and increases characteristic fluctuation.

In view of the above problems, the present invention is inexpensive,
It is another object of the present invention to provide a motor brake mechanism capable of obtaining stable braking performance even when used for a long time.

[0013]

SUMMARY OF THE INVENTION In short, the present invention provides a method of forming a groove in a brake surface or the like to form a rough surface (rough surface processing) so that the frictional resistance between the brake surface and the brake pad is increased. Is increased, whereby the brake pressure can be reduced.

That is, the brake mechanism of the electric motor of the present invention
A rotor case attached to the rotating shaft of the motor and this rotor
Cover both ends of the outer peripheral surface of the motor case.
FG magnet with a U-shaped cross section fixed by
The magnetized surface formed on the outer peripheral surface of the magnet and the FG
The brake surface formed on the outer peripheral surface of the
Press on the brake surface and the grooves formed on the brake surface.
And a brake pad to be pressed .

Further, a brake mechanism for an electric motor according to the present invention.
Is a rotor case attached to the rotating shaft of the motor.
With multiple grooves formed on the outer peripheral surface of the rotor case
Brake surface and the outer peripheral surface of the rotor case
Step and the upper part formed by denting
FG mag that is fixed to cover a part of the groove on the brake surface
The net and the dressing formed on the outer peripheral surface of this FG magnet
A magnetic surface, and a brake pad pressed against the brake surface.
It is characterized by having.

[0016]

[Function] By roughening the brake surface, the contact area between the brake surface and the brake pad is increased, and the frictional resistance between the brake surface and the brake pad is increased, thereby obtaining the same brake performance as compared with the conventional structure. Brake pressure can be reduced. For this reason, the component strength of the brake mechanism can be reduced. Further, the degree of wear of the brake surface and the brake pad, or the sliding load between the motor bearing and the rotating shaft can be suppressed low.
Therefore, stable braking performance can be obtained even when used at low cost for a long time.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake mechanism according to an embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a brushless capstan motor having a brake mechanism according to an embodiment. This motor is incorporated in a VTR deck, for example, for running the video tape 5, and has substantially the same structure as the structure shown in FIG. Then, the video tape 5 runs in contact with the capstan shaft (rotating shaft) 3 by the pressing by the pinch roller 4, and the video tape 5 runs stably by the driven of the pinch roller 4. The rotation of the capstan shaft 3 is transmitted to other parts via the upper pulley 6 and the reel belt 2. The rotor case 1 is integrally fixed to the capstan shaft 3.

A brake surface 15 is provided on the outer periphery of the rotor case 1.
Are formed. In the vicinity of the outer periphery of the rotor case 1,
A brake unit 20 comprising a brake lever 22 having a brake pad 23 fixed to an end thereof, and a spring 21 for urging the brake lever 22 in a predetermined direction.
Is provided. Brake lever 22 is spring 2
1 and a force acting via a mechanism (not shown) or the like, rotates about its central axis 22a. This rotation causes the brake pad 23 to move in contact with or away from the brake surface 15 of the rotor case 1 as indicated by an arrow. In the illustrated example, the brake pad 23 is separated from the brake surface 15 by the urging force of the spring 21 when the brake operation is not performed.

FIG. 2 shows details of the portion A in FIG. In FIG. 2A, a drive magnet 12 is integrally attached to the inner peripheral surface of the rotor case 1. An FG magnet having a U-shaped cross section is provided on the outer peripheral surface of the rotor case 1.
13 covers a part of both ends of the outer peripheral surface of the rotor case 1.
And are fixed together. An outer peripheral surface of the FG magnet 13 is provided with a magnetized surface 14 that is magnetized at a predetermined interval in an outer peripheral direction and protrudes. FG magnet 13
Of the brake surface 1 above the magnetized surface 14
5 are formed. A plurality of grooves are formed on the brake surface 15 by processing such as cutting and pressing. A brake pad 23 provided on the brake lever 22 is located to face the brake surface 15.

FIG. 2B shows an example in which a brake surface 15 having a plurality of grooves is formed directly on the outer peripheral surface of the rotor case 1. More specifically,
The outer peripheral surface of the rotor case 1 has a plurality of grooves
Brake surface 15 is formed and the brake surface
15 below the brake surface.
A step portion 30 is formed. This step 30 and the above blur
The stepped portion 30 slides over a part of the groove of the
The FG magnet 13 covers a part of the groove of the
It is fixed. Magnetized on the outer peripheral surface of FG magnet 13
Surface 14 is formed. Here, since the rotor case 1 is usually made of a metal member, the brake surface 15 which is a contact portion with the brake pad 23 becomes a metal member, so that the wear resistance of the brake surface 15 can be enhanced. Further, by forming the grooves by press working, there is an advantage that the manufacturing cost is low and burrs due to cutting are not generated.

Further, as shown in FIG. 2C, a member 16 having a brake surface 15 similar to the above example may be integrally fixed to the outer periphery of the rotor case 1. By using the brake surface 15 as another member 16 in this manner, the replacement of the brake surface 15 due to wear can be completed only by this member 16.

FIGS. 3A to 3E show examples of grooves formed on the brake surface 15 provided on the outer periphery of the rotor case 1 in the present invention.
It is an enlarged view of the B section in (b). (A) shows an example in which a groove having a V-shaped cross section is provided, (b) shows an example in which a groove having an arc-shaped cross section (a U-shaped cross section) is provided, and (c) shows a brake surface processed into an arc-shaped wave. (D) is an example in which a rectangular groove is provided,
(E) shows an example in which the brake surface is machined into a triangular waveform.

The purpose of providing such a groove is to increase the contact area on the brake surface. So the groove is
A plurality may be provided at equal intervals or at different intervals. The groove shape may be the same shape continuous or different shape continuous or discontinuous. Furthermore, the groove depth, the number of grooves, and the like may be appropriately determined according to the allowable space for the motor, the brake pad, and the like. Further, instead of forming the groove, the brake pad 2 on the brake surface 15 may be formed by a known roughening treatment.
3 may be enlarged.

FIGS. 4 and 5 respectively illustrate the steps of manufacturing the rotor case 1 used in the embodiment of the present invention.

In the example shown in FIG. 4, the flat plate 3 shown in FIG.
From FIG. 4, the disk-shaped rotor case 1 shown in FIG. And this rotor case 1
Is pressed in a planar state by, for example, a punch having a plurality of grooves formed concentrically to form, for example, a V-shaped groove on the brake surface 15 as shown in FIG. Further, as shown in FIG. 4D, the disk-shaped rotor case 1 is bent by approximately 90 degrees inward with respect to the outer peripheral brake surface 15 by drawing or the like. Further, an FG magnet is provided on the outer periphery of the rotor case 1 by molding.

FIG. 5 exemplifies a case in which a groove is formed on the brake surface 15 by a progressive or transfer molding technique. In the course of processing one after another from a flat plate as shown in FIG. 5 (a) to a desired rotor case shape, the outer peripheral surface of the rotor case 1 is grooved as shown in FIG. Is formed. Further, the outer peripheral portion of the rotor case 1 is bent inward as shown in FIGS. 5C to 5D to form a rotor case, and then, as shown in FIG. Are integrally molded. Alternatively, a V-shaped groove may be formed by, for example, rolling.

In the above description, the FG magnet 13 may be configured such that only necessary parts for fulfilling the function for FG are integrally formed as shown in FIG. With this configuration, the case thickness of the lower end portion of the rotor case 1 can be reduced, the FG magnet material can be reduced while maintaining the FG magnet strength, and the material cost is reduced accordingly. In addition, the cutting cost of the FG magnet, which is required when a braking surface is provided on the FG magnet, is not required, so that the processing cost is reduced. Furthermore, since it is processed and formed on metal, its hardness is higher than that of forming on a plastic FG magnet, and therefore, dents are less likely to be formed during processing and forming, and defects are less likely to occur.

FIG. 6 shows an apparatus for measuring the brake characteristics of the brake mechanism of the embodiment and the conventional brake mechanism, respectively. That is, the current value flowing through the motor when the pinch roller 4 is pressed against the capstan shaft 3 of the motor and the brake surface 15 of the rotor case 1
And the current value when the brake pad 22 is pressed against each other is measured by the ammeter 7, and these measured values are expressed as X
Traced by -Y recorder 8. FIG. 7 shows the result of the trace.

FIG. 7A shows the result when the rotor case 1 having the structure shown in FIG. 2B is used. The initial value when the pinch roller is pressed and the brake pad are pressed. It can be seen that the current amplitude at the time is stable.

FIG. 7 (b) shows the result when the rotor case 1 having the structure shown in FIG. 2 (a) is used. The amplitude of the current slightly varies, but is relatively stable as described above. You can see that.

FIG. 7 (c) shows the result when a conventional rotor case having a flat brake surface without a groove is used, and the current amplitude varies.

[0033]

According to the present invention configured as described above, the frictional resistance increases due to the increase in the contact area between the brake surface and the brake pad. Brake pressure can be reduced. Therefore, the following effects are obtained. (1) Since the wear of the brake surface and the brake pad and the sliding load between the motor bearing and the rotating shaft can be suppressed low, stable braking performance can be obtained even when used at low cost for a long time. (2) Since the brake pressure can be reduced, the strength of the components of the brake mechanism can be reduced, and the manufacturing cost can be reduced. Further, according to the present invention, a rotor case of an electric motor is provided.
FG mag which covers a part of both ends of the outer peripheral surface of
Secure the net or attach it to the outer surface of the rotor case.
Step formed by recessing from the brake surface
Part and the brake surface formed on the outer peripheral surface of the rotor case.
Since the FG magnet was fixed to cover a part of the groove,
Prevent the G magnet from falling out of the rotor case
And the FG magnet outside the rotor case.
It can be securely and firmly fixed to the peripheral surface.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a brushless capstan motor having a brake mechanism according to an embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views each showing a main part of a brake mechanism according to an embodiment.

3 (a) to 3 (e) are explanatory views each exemplifying a groove shape formed on a brake surface on the outer periphery of a rotor case in the present invention.

FIGS. 4 (a) to 4 (e) are explanatory views of a manufacturing process of the rotor case according to the embodiment of the present invention.

FIGS. 5 (a) to 5 (f) are explanatory views of a manufacturing process of the rotor case according to the embodiment of the present invention.

FIG. 6 is an explanatory view showing an apparatus for measuring brake characteristics of the brake mechanism of the embodiment and a conventional brake mechanism.

7 shows the measurement results according to FIG. 6, wherein (a) and (b) show the results of the embodiment, and (C) shows the results of the conventional example.

FIG. 8 is an explanatory diagram showing a configuration of a brushless capstan motor for a VTR.

[Explanation of symbols]

 Reference Signs List 1 rotor case 3 capstan shaft 4 pinch roller 12 drive magnet 13 FG magnet 15 brake surface 22 brake lever 23 brake pad

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 15/22 G11B 15/26

Claims (2)

(57) [Claims] 1. A rotor case attached to a rotating shaft of an electric motor , and both ends of the outer peripheral surface are provided on the outer peripheral surface of the rotor case.
FG magnet with a U-shaped cross section
And a magnetized surface formed on the outer peripheral surface of the FG magnet
And a brake formed on the outer peripheral surface of the FG magnet
Surface, and a plurality of grooves formed in the brake surface,
A brake mechanism for an electric motor, comprising: a brake pad pressed against a brake surface . 2. A rotatable device mounted on a rotating shaft of an electric motor.
And the plural pieces formed on the outer peripheral surface of this rotor case
Brake surface having a groove, and an outer peripheral surface of the rotor case
Formed by recessing above the brake surface
Fixed over the stepped part and a part of the groove on the brake surface.
FG magnet and the outer surface of this FG magnet
And a brake pressed against the brake surface.
And a pad for the motor.
Key mechanism.