JPH0427512Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to small electric appliances such as electric razors, electric hair clippers, or electric pine surgers.

[Conventional technology]

As a small electric device of this type, one is known in which an eccentric cam is fixed on the rotating shaft of a motor, and the rotational motion of the motor is converted into a required linear reciprocating motion by the eccentric cam.

As a means of fixing an eccentric cam to the rotating shaft of a motor, there is a method in which a shaft hole provided in the eccentric cam is simply press-fitted to the rotating shaft, but with this, when a load is applied to the eccentric cam, the eccentric cam A problem occurs in that idling occurs between the shaft hole and the rotating shaft, making it impossible to transmit power.

As a means for preventing the eccentric cam from idling, for example, as shown in FIGS. 4 and 5, a part of the peripheral surface of the rotating shaft 6 of the motor 5 is cut flat to form a semicircular cross section, and the shaft cross section is A filling 21, which is a plastic molded product, having a shaft hole 20 having the same shape as the shaft hole 20 is molded, and this is fitted into the shaft hole 7a of the eccentric cam 7. If only the filling 21 is fitted, idling will occur between the filling 21 and the shaft hole 7a of the eccentric cam 7. To prevent this, a pin 22 is driven into a part of the circumferential surface of the eccentric cam 7, and the tip of the pin 22 is inserted into the shaft hole 7a of the eccentric cam 7. There is one in which the padding 21 is engaged with a recess 23 in a part of the circumferential surface of the stuffing 21.

[Problem that the invention attempts to solve]

However, the above-described idling prevention means for the eccentric cam 7 requires the filler 21 and the pin 22 in addition to the eccentric cam 7, which has the disadvantage of increasing the number of components and the number of assembly steps.

Therefore, this invention aims to prevent idling between the rotating shaft of the motor and the shaft hole of the eccentric cam in a small electric device equipped with a motor in which an eccentric cam is fixed to the rotating shaft as described above, and also has a structure for preventing idling. The purpose is to simplify the

[Means for solving problems]

This idea is based on the assumption that the shaft hole 7a of the eccentric cam 7, which has a lower hardness than the shaft 6, is press-fitted into the rotating shaft 6 of the motor 5, and then a plurality of grooves 17 are formed in the circumferential surface of the rotating shaft 6 in the axial direction. A burr 18 is provided along the opening of each groove 17 so as to protrude radially outward from the circumferential surface of the rotating shaft 6, and when the eccentric cam 7 is press-fitted, the burr 18 is inserted into the inner surface of the shaft hole 7a of the eccentric cam 7. By biting into the rotating shaft 6 and the eccentric cam 7,
This is to prevent idling between the shaft hole 7a and the shaft hole 7a.

[Effect]

In this case, contact pressure (fitting pressure) is generated on the contact surface (fitting surface) between the inner surface of the shaft hole 7a of the eccentric cam 7 and the circumferential surface of the rotating shaft 6, and if a load is applied to the eccentric cam 7 side, The friction force resists this, and this resistance force is further increased by the engagement force of the burr 18 on the rotating shaft 6 biting into the inner surface of the shaft hole 7a of the eccentric cam 7, making it possible to transmit a relatively large force. .

[Effect of idea]

In this invention, a plurality of grooves 17 are provided along the axial direction on the circumferential surface of the rotating shaft 6, a burr 18 is provided at the opening end of each groove 17, and a shaft hole 7 of the eccentric cam 7 is provided in the rotating shaft 6.
a is press-fitted so that the burr 18 bites into the inner surface of the shaft hole 7a of the eccentric cam 7. Therefore, the eccentric cam 7 can be easily assembled by simply press-fitting the eccentric cam 7 onto the rotating shaft 6. Moreover, the rotation shaft 6 and the shaft hole 7 of the eccentric cam 7 are affected by the load.
It is possible to effectively and reliably prevent idling between a and a. In addition, the burr 18 has a groove 1 in the rotating shaft 6.
There is also an advantage in machining that a sharp shape that can easily bite into the inner surface of the shaft hole 7a of the eccentric cam 7 can be easily formed by actively generating the shaft hole 7 by cutting the shaft hole 7a.

〔Example〕

Hereinafter, a case will be described in which an embodiment of the present invention is applied to a reciprocating electric shaver.

In Fig. 3, 1 is the main body case of the electric shaver, 2 is a reciprocating inner blade disposed on the upper part of the main body case 1, and 3 is an outer blade holder detachably attached to the upper part of the main body case 1. , a mesh-like outer cutter 4 is bent to have an arcuate cross section and is held so as to cover the upper part of the inner cutter 2.

A motor 5 is housed inside the main body case 1,
An eccentric cam 7 for converting the rotational movement of the motor 5 into a reciprocating linear movement of the inner cutter 2 is fixed onto the rotating shaft 6 of the motor 5. An eccentric pin 8 is provided protruding from the upper end surface of the eccentric cam 7, and this eccentric pin 8 is connected to the motor 5.
It is connected to a vibrator 9 placed above it by a connecting rod 10. The vibrator 9 is a plastic molded product, and has a vibrator body 12 having a drive shaft 11 that supports the inner cutter 2, and elastically deformable thin legs 13, 13 connected to the left and right ends of the vibrator body 12. The upper ends 13a of both legs 13, 13 are supported and fixed to the inner surface of the upper wall 14 of the main body case 1 with screws 15.

The drive shaft 11 of the vibrator 9 is connected to the upper wall 1 of the main body case 1.
4 protrudes upward from the central opening, and the inner cutter 2 is coupled to this protruding end with an inner cutter holder 16.

Now, when the motor 5 rotates, this rotation is transmitted to the vibrator 9 via the eccentric cam 7 and the connecting rod 10, and the vibrator 9 reciprocates in the left and right horizontal directions through the elastic deformation of the thin legs 13, 13. Along with this reciprocating movement, the inner cutter 2 slides on the inner surface of the outer cutter 4 and makes a reciprocating linear movement in the left-right direction. Of course, the connecting rod 10 can be omitted and the eccentric pin 8 of the eccentric cam 7 can be connected directly.
It may be slidably engaged with a long groove provided on the lower surface side of the vibrator 9.

In the above structure, this invention is characterized by means for fixing the eccentric cam 7 to the rotating shaft 6 of the motor 5.

1 and 2, a plurality of thin grooves 1 having a substantially V-shaped cross section are formed on the circumferential surface of the rotating shaft 6 of the motor 5.
7 is cut along the axial direction, but at this time, each groove 1
It is formed by actively generating a sharp burr 18 having a substantially V-shaped cross section at the tip of the opening.

The eccentric cam 7 is made of a material whose hardness is lower than that of the rotating shaft 6, and has a shaft hole 7a having a circular cross section. For example, with respect to the rotating shaft 6 made of stainless steel, the eccentric cam 7 is made of a die-cast molded product of zinc, aluminum, or the like. The eccentric cam 7 may also be made of brass or plastic. However, the planar shape of the eccentric cam 7 is not only circular but also elliptical, fan-shaped, etc.

Thus, the shaft hole 7a of the eccentric cam 7 is press-fitted into the rotating shaft 6, and the burr 18 is bitten into the inner surface of the shaft hole 7a of the eccentric cam 7.

In such cases, when using this razor, even if a load is applied when, for example, pressing the outer blade 4 strongly against the face or cutting beard, there will be no idling between the rotating shaft 6 and the shaft hole 7a of the eccentric cam 7. This problem did not occur and normal drive transmission was achieved.

In fact, when comparing the idling torque of the motor 5 without the burr 18 on the rotating shaft 6 and the proposed motor 5 with the burr 18, the former's idling torque was 2.5 to 3 kg/cm. On the other hand, in the latter case, the torque was 7 to 8 kg/cm, which was about 2.5 times as much as the idling torque.

However, the diameter of the rotating shaft 6 made of stainless steel is 2
mm, the diameter of the eccentric cam 7 made of zinc die casting is 9
mm, four grooves 17 are provided at equal angles on the circumferential surface of the rotating shaft 6, the depth A of each groove 17 is 0.04 to 0.05 mm, and the burr is 1 mm.
The height B of 8 is 0.015 to 0.020 mm.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, in which Figure 1 is a front view of a motor equipped with an eccentric cam, Figure 2 is an enlarged cross-sectional view taken along the - line in Figure 1, and Figure 3 FIG. 2 is a partially cutaway front view of the electric shaver. 4 and 5 show a conventional eccentric cam motor, with FIG. 4 being a front view and FIG. 5 being an enlarged sectional view taken along the line - in FIG. 5... Motor, 6... Rotating shaft, 7... Eccentric cam, 7a... Shaft hole, 17... Groove, 18... Burr.

Claims (1)

[Claims for Utility Model Registration] A small electric device equipped with a motor 5 in which an eccentric cam 7 whose hardness is lower than that of the shaft 6 is press-fitted and fixed to the rotating shaft 6. 17 is carved along the axial direction, and a burr 18 is provided at the opening end of each groove 17 to protrude radially outward from the circumferential surface of the rotating shaft 6, and the burr 18 is inserted into the inner surface of the shaft hole 7a of the eccentric cam 7. A small electrical device characterized by being inserted into the body.