JPS6141417Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a protection mechanism for the bearing case of an electric motor that absorbs vibrations generated as the output shaft rotates and prevents the vibrations from being transmitted to the bearing case that holds the bearing that supports the output shaft. Regarding a shaking device.

Generally, an electric motor used in a precision machine, for example, has a permanent magnet fixed in a housing around the output shaft, and a permanent magnet arranged concentrically with the output shaft so as to surround the radial outer circumferential surface of the output shaft of the permanent magnet. In a coreless motor equipped with a cylindrical coil fixed to an output shaft so as to rotate together with the output shaft, the output shaft is supported near the base end where the commutator is provided by a first bearing. Also, the vicinity of the protruding end protruding from the housing into the external space is pivotally supported by a second bearing. The first bearing and the second bearing are held by a bearing case that is fixed within the housing of the electric motor and extends around the output shaft in the direction in which the output shaft extends.

Since the bearing case is fixed to the housing only at the portion corresponding to the tip side of the output shaft, the portion corresponding to the base end side of the output shaft is extended from the portion corresponding to the tip side. It can be considered as the tip of a cantilever. A conventional bearing case having such a configuration has a drawback that, as the output shaft rotates, the base end side of the output shaft vibrates around the tip end side of the output shaft. And this vibration is
The information is transmitted to the motor housing via the output shaft, so if the precision equipment to which the coreless motor is attached is, for example, a small cassette tape recorder that fits in the pocket of a Shinto priest's suit, the built-in This causes noise when recording with a microphone.

This invention was made based on the above circumstances, and the purpose of this invention is to absorb the vibrations generated at the base end of the output shaft as the output shaft rotates, and to hold the bearing that supports the output shaft. An object of the present invention is to provide a vibration isolating device for a bearing case of an electric motor, which prevents vibrations from being transmitted to the bearing case.

Examples of this invention will be described below with reference to the drawings. An electric motor 10 using a coreless motor includes a cylindrical shield case 14 that covers the output shaft 12 along the direction in which the output shaft 12 extends, and a circular outer periphery having a diameter smaller than the diameter of the inner peripheral surface of the shield case 14. A front end plate 16 and a rear end plate 18 inserted into openings at both ends of the prepared shield case 14.
and a housing. The front end plate 16 and the rear end plate 18 are connected to the output shaft 12.
They are interconnected by a frame 19 that extends parallel to the inner circumferential surface of the shield case 14 in the extending direction of the shield case 14 . The frame 19, the front end plate 16, and the rear end plate 18 are made of anti-vibration rubber 2.
0 and 22, and is indirectly attached to the inner peripheral surface of the shield case 14.

A loose fitting hole is formed in the radial center of the front end plate 16, and one end of the output shaft 12 projects from this loose fitting hole to form a tip. Front end plate 1 facing inward of shield case 14
At the radial center of the inner surface of 6, there is a cylinder having an inner circumferential surface having a diameter larger than the diameter of the output shaft 12 and extending in parallel with the outer circumferential surface of the output shaft 12 toward the inside of the shield case 14. The portion 24 is fixed by integral molding. The front end plate 16 and the cylindrical part 24 constitute a bearing case 26, and the extending end of the cylindrical part 24 and the loose fitting hole of the front end plate 16 are provided with first and second oilless bearings. 2
8 and 30 are held, respectively. The output shaft 12 is
It is pivotally supported by the bearing case 26 by these oilless bearings 28 and 30.

Partially cylindrical N-pole and S-pole permanent magnets 32 and 34 are disposed on the radially outer side of the cylindrical portion 24 with respect to the output shaft 12 and on the inner side of the frame 19. , 34 is the cylindrical part 2
4, and extends along the outer periphery of the front end plate 1.
It is fixed to the inner surface of 6 with adhesive. In addition, an output shaft 12 is located inside the frame 19 and radially outward of the output shaft 12 of the permanent magnets 32 and 34.
A cylindrical coil 36 fixed to the output shaft 12 so as to rotate together with the output shaft 12 is arranged in a circular shape concentric with the output shaft 12 so as to surround the outer peripheral surface of the permanent magnets 32 and 34.

The end surface of the other end of the output shaft 12, that is, the base end, is
Since the output shaft 12 is in contact with a bracket 38 attached to the inner surface of the rear end plate 18 facing inward of the shield case 14, the output shaft 12 is prevented from thrusting. A commutator 40 is provided at the base end of the output shaft 12.
The brush 4 fixed to the bracket 38 is
2 are in contact. Then, when a current input from the outside of the motor 10 is passed through the brush 42, the output shaft 12 is connected to the coil 36, the permanent magnet 32,
It rotates by the action between it and 34.

Further, the inner circumferential surface of a vibration isolating member 44 formed of cylindrical rubber is fitted onto the outer circumferential surface of the extending end of the cylindrical portion 24 holding the first oilless bearing 28. . A partial annular recess 46 is formed on the inner circumferential surface of the permanent magnets 32 and 34 in a portion facing the vibration isolating member 44, and the diameter of this recess 46 is equal to the diameter of the vibration isolating member 44. The width of the recess 46 in the direction in which the output shaft 12 extends is equal to the width of the vibration isolating member 44 in the direction in which the output shaft 12 extends. The vibration isolating member 44 is fitted into this recess 46 and fixed with adhesive.

As detailed above, in this invention, by providing a vibration isolating member connected to the bearing case and the permanent magnet near the first bearing, vibrations generated at the base end of the output shaft as the output shaft rotates. Since the bearing case can absorb the vibrations caused by the bearing, it can prevent the vibrations from being transmitted to the bearing case.

Note that this invention is not limited to the above embodiments; for example, the material of the vibration isolating member is not limited to rubber, but may be any material that can absorb vibrations.
Further, the shape is not limited to a cylindrical shape, and may be a partially divided cylindrical shape.

[Brief explanation of the drawing]

The figure is a sectional view showing an embodiment of this invention. 10... Electric motor, 12... Output shaft, 14... Shield case, 16... Front end plate, 18... Rear end plate, 19... Frame, 20... Anti-vibration rubber, 22... Anti-vibration rubber, 24...Cylindrical part, 26...
... Bearing case, 28 ... First oil-less bearing, 30 ... Second oil-less bearing, 3
2... Permanent magnet, 34... Permanent magnet, 36... Coil, 40... Commutator, 42... Brush, 44...
...Vibration isolation member.

Claims (1)

[Scope of utility model registration request] Fixed within the housing of the motor, extending around the output shaft of the motor in the direction in which the output shaft extends, and protruding from the bearing on the base end side where the commutator of the output shaft is provided and the housing of the output shaft. A bearing case that holds the bearing on the tip end side together; a permanent magnet that is fixed to the tip side of the bearing case and extends in the direction in which the output shaft extends radially outward of the output shaft; It is disposed between the base end side and the permanent magnet, and indirectly connects the base end side bearing and the permanent magnet. A vibration isolating device for a bearing case of an electric motor, comprising a vibration isolating member.