JPS5944192B2 - electric screwdriver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric screwdriver, and more particularly, to an electric screwdriver that can be used both electrically and manually for forward and reverse rotation.

In general, the entire rotation process of a screw when attaching a screw to a screw hole in which a female thread has been cut in advance and when removing a screw screwed into the screw hole consists of approximately two different processes. I can do it.

In other words, tightening is sometimes a process of screwing in, in which the tip of the screw makes contact with the screw hole, and continues rotating without slight resistance until the head of the screw makes contact with the edge of the screw hole, and loosening. It consists of a removal process which is the reverse of the above when removing, a tightening process in which the screw is tightened firmly by overcoming great resistance, and a loosening process in which the tightly tightened screw is loosened with great force.

Therefore, although the frictional resistance is generally slight during the initial screwing-in stroke and the unscrewing stroke, it is necessary to apply a large number of rotations because the distance is long.

On the other hand, in the final tightening stroke and loosening stroke, there is great resistance, but the number of revolutions is extremely low.

However, various types of automatic screwdrivers using electric power or compressed air as a power source have been developed and put into practice for installing and removing such screws.

However, all conventional automatic screwdrivers are designed to complete the entire process of screw installation and removal using pneumatic or electric power.

Therefore, they were designed with the concept of being able to release torque that overcomes the maximum resistance during the tightening and loosening strokes, and a powerful power source was installed, and the compressed air type was thick and heavy due to high-pressure air transport. Since it involves the use of a hose and requires a powerful motor, it is difficult to use in both weight and volume, and is suitable for installing and removing machine screws, etc., which require relatively precise operations. were inappropriate because they were operated inadvertently and were noisy and dangerous.

Furthermore, even with these powerful power sources, when it comes to confirming whether the final tightening has been completed, it is necessary to rely on the tactile sensation of manual operation by humans. Therefore, after tightening with an automatic screwdriver, it was necessary to perform inspection and confirmation using another manual screwdriver.

Therefore, in recent years, various developments have been made and various inventions have been proposed in order to eliminate the problems and drawbacks that such automatic drivers have.

As an example, we can cite Japanese Patent Publication No. 47-42599 and Japanese Patent Publication No. 47-49360, both of which have low initial frictional resistance and automatic rotation using electric power for long screw-in operations. The final tightening process, which is subject to relatively large resistance, can be performed manually by leaving it to the mechanism, and the screws are tightened using a special screwdriver.

By the way, the reason why it is desirable to use both automatic rotation by electric power and manual rotation as described above is not only for tightening screws, but also for loosening and removing screws, and especially for service work ( For after-sales repairs, etc., an electric screwdriver that can be switched between electric and manual for both installing and removing screws is required.

Therefore, as a result of extensive research, the inventors of the present invention discovered that forward rotation,
We have succeeded in developing an electric screwdriver that can be used by switching between electric and manual operation, both when rotating in the so-called screw installation direction and when rotating in the reverse direction, so-called screw removal direction.

A first object of the present invention is to provide a small-sized electric screwdriver that can be used for both forward and reverse rotation and can be switched between electric and manual modes, and is suitable for service work (after-sales repairs) and the like.

A second object of the present invention is that when the rotational force exceeds the tightening torque during manual rotation work, the outer race, which is in charge of transmitting the rotational force, separates from the housing, causing the housing to spin idly. To provide an electric screwdriver whose torque can be adjusted manually.

Furthermore, other objects and advantages of the invention will become more apparent from the detailed description that follows.

Next, an embodiment of the electric screwdriver according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, a housing 1 is formed into a cylindrical shape, as is clear from the cross-sectional view in FIG. 2, and a motor 2 and a speed reducer 3 are mounted inside.

A pinion gear 5 is fixed to the rotating shaft 4 of the motor 2, and the pinion gear 5 is connected to a reduction gear 3 constituted by a planetary gear mechanism.

The reducer 3 is a combination of two planetary gear mechanisms, each consisting of an internal gear 6 that is fitted and fixed inside the housing 1, and a planetary gear 7 that rotates while meshing with the internal gear 6. The planetary gears 7 are pivotally supported at three locations on the disk 8 at equal intervals, and the three planetary gears 7 are meshed with the pinion gear 5 described above.

A gear cylinder 9 that meshes with the planet gear γ' of the second stage planetary gear mechanism is integrally fixed to the center of the disk 8 in the first stage planetary gear mechanism, so that the second stage planetary gear mechanism The disk/retainer 8' constituting the gear mechanism is on the output side of the decelerated rotation.

Although the speed reducer 3 shown in Figure 1 is a combination of two planetary gear mechanisms, this can be changed as appropriate depending on the desired speed reduction ratio.

A retainer is fixed to a disk 8' which is the output side of the reducer 3; in the case shown, the disk 8 also serves as a retainer, and the retainer is attached to the disk 3' and the end bearing part of the housing 1. The rotational force of the motor 2 is connected by the cam 11 at the rear end of the shaft 10 which is supported through the shaft 1', the engagement pin 12 fixed to the cam 11 side, and the engagement circular arc hole 13 made in the octavalent disc. 3, and is transmitted to the shaft 10 to which the bit is connected.

The cam 11 at the rear end of the shaft 10 is formed into a generally triangular rice ball shape, and each periphery of its outer circumferential surface is the center or the smallest diameter part, and the diameter increases toward the left and right sides. It is formed.

Disc 8' (7) that also serves as a retainer has a protruding piece 14 on the outer periphery.
are protruded from three locations at equal intervals, and the protruding positions of the protruding pieces 14 are on a line connecting the center of the disc 8' and the center of the engaging circular arc hole 13, and the power generated by the rotation of the motor 2 is During operation, the engaging body 15 can be positioned and maintained on the minimum diameter portion of the cam 11.

The shape of the engaging body 15 is not limited to the cylindrical shape shown in the figure.
Examples include spherical shape and crescent shape.

The engaging body 15 is mounted between the outer peripheral surface of the cam 11 and the inner surface of the outer race 16 attached to the inside of the housing 1), and the position of the engaging body 15 changes. It can be switched, electrically operated, or manually operated.

Outer race 16 attached to the inside of housing 1
is formed into a ring shape and is fixed integrally to the housing or is attached in an overload-connected manner via a clutch mechanism 17 as shown.

The clutch mechanism 17 includes a hemispherical recess 18 formed on the outer peripheral surface of the outer race 16, a ball 19 fitted in the recess 118, a spring 20 that presses the ball 19, and adjusts the elastic force of the spring 20. Adjustment rod 21
If a force greater than the elastic force of the spring 20 is applied to the shaft 10, the housing 1 will slip relative to the outer race 16.

In addition, the electric power supply to the motor 2 in the present invention may be performed either by a battery or by connecting a cord to a general household power source. Therefore, the electric screwdriver according to the present invention may be a cordless electric screwdriver or a corded electric screwdriver. It can take both forms.

Next, a detailed explanation of the present invention will be provided (first, the housing 1).
Switch 22 attached to the circumference of the switch is ONL.

When the rotating shaft 4 of the motor 2 is rotated in the forward direction, the rotation of the rotating shaft 4 is transmitted through the pinion gear 5 → planetary gear 7 → disc 8 → gear cylinder 9 → planetary gear 7' to reduce the speed of the rotation to the disc 81. At the same time, the rotation is further caused by the cam 1 on the left side of the engaging circular arc hole 18.
By abutting and engaging the engagement pin 12 on the first side, the cam 11
The shaft 10 to which the bit 23 is connected
It can be rotated electrically.

Therefore, it is possible to instantaneously accomplish a screw-in stroke with slight resistance until the head of the screw reaches the edge of the screw hole using electric power.

At this time, the engaging body 15 inserted between the outer peripheral surface of the cam 11 and the inner surface of the outer race 16 is positioned and held on the minimum diameter portion of the cam 11 by the projection piece 14 of the disc 8'. The radius of the minimum diameter part of the radius cam 11 of the engaging body 15 is maintained as the inequality of the outer race 16, so that the cam 11 is not fixed to the outer race 16 and can move relative to the outer race 16c. (See Figure 3).

Screw it in using the electric power as described above and click) 2
When a load greater than the maximum shaft output of the shaft 10 is applied to the motor 3, the rotation of the motor 2 is locked.

At this time, when the housing 1 to which the outer race 16 is fixedly or overloaded is rotated, the engaging body 15 moves clockwise on the circumferential surface of the cam 11, and the engaging body 15 moves clockwise on the circumferential surface of the cam 11. When the inequality condition of 10 radius of cam 11 ≧ outer race 16 is reached, housing 1
, the outer race 16, the engaging body 15, and the cam 11 are integrally connected, and the rotational force applied to the housing 1 is transmitted from the outer race 16 to the engaging body 15 to the shaft 10 having the cam 11. This allows manual tightening.

Furthermore, if the motor switch is kept in the ON state in the feed direction at this time, single-feed tightening by manual operation is also possible.

Therefore, the final tightening of the screws can be carried out manually (see FIG. 4).

The above shows that the tightening is sometimes a forward rotation operation, but the fifth
The figures and FIG. 6 show the reverse rotation operation when removing a tightened screw.

In other words, when removing a screw that has been tightened, a large amount of force is required at first, so this is done manually.As with manual operation during normal rotation, when the housing 1 is rotated counterclockwise, the The engaging body 15 moves counterclockwise on the circumferential surface of the cam 11 and engages the outer race 16.
, the engaging body 15 and the cam 11 are integrally connected, /'
The rotational force applied to %Using 1 is the outer race 16
→Shaft 10 with cam 11 via engaging body 15/
This allows the manual loosening operation to be performed.

Therefore, the loosening operation that requires the most force in removing screws can be reliably performed manually (No. 5
(see figure).

After loosening the circle t<b above, turn on the switch and reverse the motor 2, and the rotational force of the sweater 2 will be transferred to the rotation shaft
→Pinion gear 5→Planetary gear 7→Disk 8→Gear cylinder 9→
The deceleration is transmitted to the disc 8' via the planetary gear 7', and the rotation is further interlocked with the cam 11 by abutting and engaging the engagement pin 12 on the cam 11 side with the right side of the engagement arc hole 13. The shaft 10 to which the bit 23 is connected is electrically rotated.

Therefore, the loosened screw can be instantly removed by electric power (see Fig. 6).

The above is the effect when the outer race 16 is fixed to the housing 1, but when the outer race 15 is connected to the housing 1 through the clutch mechanism 17 as shown in FIG. It is possible to manually adjust the torque in both forward and reverse rotations, and if an external force that exceeds the set torque is applied, the housing 1 will slip and prevent over-tightening during manual operation. In addition, when screwing into relatively soft screws such as synthetic resin or base materials made of these materials, the intended purpose can be achieved smoothly without damaging the screws or the base material. You can.

Note that the speed reducer in the present invention is not limited to the illustrated planetary gear mechanism ζ, and it is of course possible to use a speed reducer that is well known today and can exhibit the same effect.

Further, when using the electric screwdriver according to the present invention, the switch is turned ON and the housing 1 is rotated like a ratchet feed, thereby producing an effect like a feed tightening operation.

Although the preferred embodiments of the driver of the present invention have been described above, it goes without saying that the design may be modified as desired without departing from the spirit of the present invention.

As described above, since the electric screwdriver according to the present invention can switch between zero electric and manual rotation for both forward and reverse rotation, it is possible to perform almost the entire screw tightening operation and to remove loosened screws. The entire removal process can be done instantly using the electric power of a small rotor, and the final tightening and loosening of tightened screws can be done reliably by manually rotating the housing slightly. It is something that can be done.

Moreover, switching from electric power to manual power for both forward and reverse rotations can be done automatically by simply rotating the housing slightly clockwise (for forward rotation) or counterclockwise (for reverse rotation). It is very convenient and can facilitate workability.

Furthermore, if the outer race attached to the inside of the housing is used as an overload connection via a clutch mechanism, the torque can be adjusted during manual operation to prevent over-tightening, or to prevent over-tightening. This can be effective in preventing damage to soft screws and base materials made of these materials.

In addition, since electric power and manual power can be used together, if the battery or battery power runs out in the case of cordless,
Alternatively, in the case of a corded device, even if there is no appropriate power source, screws can be installed and removed using only manual force, making it convenient for portable use.

[Brief explanation of the drawing]

The drawings show an embodiment of the electric screwdriver according to the present invention, and FIG. 1 is a partially cutaway front view showing a power transmission part, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIG. is 3- in Figure 1.
Figure 4 is a partially cutaway cross-sectional view of the state in which live power is switched to manual power in normal rotation as shown in Figure 3, and Figure 5 is a partially cut-away cross-sectional view that can be seen along line 3. FIG. 6 is a partially cutaway sectional view showing manual rotation, FIG. 6 is a partially cutaway sectional view showing the state switched to electric rotation from the state shown in FIG. 5, and FIG. 7 is a perspective view showing the entire driver of the present invention. In the figure, 1...Housing, 2...Motor, 3...Reducer, 8'...Disc (
retainer), 10...shaft, 11...
...Cam, 12...Engagement pin, 13...
... Engagement circular arc hole, 14 ... Protrusion piece, 15 ...
...Engagement body, 16...Outer race, 17.
...Clutch mechanism.

Claims (1)

[Claims] 1. A zero motor and a reducer that rotates in conjunction with the rotating shaft of the motor are built in the housing, and a retainer attached to the output side of the reducer is attached to the rear of the shaft to which the bit is connected. When the cam at the end is integrally interlocked with the engaging pin and the circular engaging hole, and the engaging body is inserted between the outer peripheral surface of the cam at the rear end of the shaft and the inner surface of the outer race attached to the inside of the housing, A projecting piece is provided on the outer periphery of the retainer to position and hold the engaging body at the minimum diameter part of the cam so that it can be tightened by the rotational force of the motor. An electric screwdriver characterized in that the engaging body is moved to the large-diameter side of the cam circumferential surface and engaged with the outer race, and manual tightening is enabled by rotating the housing. 2. The electric screwdriver according to claim 1, wherein the outer race attached to the inside of the housing is fixed to the housing. 3. The electric screwdriver according to claim 1, wherein the outer race attached to the inside of the housing is overload-connected to the housing ζ via a clutch mechanism.