JPH0645107B2 - Clutch mechanism of electric rotating tool - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque control clutch mechanism for an electric rotary tool such as an electric screwdriver, which receives a reaction force of a predetermined value or more on an output shaft when tightening a screw or the like. At this time, the transmission of the rotational force to the output shaft is cut off, and the motor and the speed reduction mechanism are idled so that the motor is not shocked or overloaded.

2. Description of the Related Art Conventionally, as a mechanism of this type, conventionally, a terminal inner gear of a planetary speed reduction mechanism that reduces the number of rotations of a motor is rotatably mounted in a gear case, and a plurality of protrusions are provided on an end surface of the gear. When an overloaded load is applied to the output shaft by pressing a ball (steel ball) that has been pressed by, the projection of the inner gear pushes back the ball and causes it to spin, thus blocking the transmission of rotational force to the output shaft. Has been done.

However, in such a mechanism, since the output shaft is instructed to and meshed with the planetary reduction mechanism, if any shock is applied to the output shaft, the shock is applied to the gear mechanism and the motor. Was transmitted, and there was a risk that these would be deformed or damaged.

Means for Solving the Problems The present invention eliminates such drawbacks, and in a clutch mechanism of an electric rotary tool having a speed reduction mechanism with an irregular mechanism in a gear case, a planet holding plate on the terminal side of the planetary speed reduction mechanism. Forming a clutch surface having a plurality of protrusions, one of which is either a mountain-shaped protrusion or a hemispherical protrusion,
A clutch plate formed with a protrusion other than the protrusion formed on the back surface of the planetary holding plate among the mountain-shaped protrusions or the hemispherical protrusions engaging with the protrusion formed on the clutch surface is rotatably attached to the end of the outer case. A feature is that a cam formed on the inner peripheral wall of the attached cover is pressed by a spring whose degree of compression can be adjusted, and the clutch plate is axially slidably displaced with respect to the output shaft. It is what

In the device of the present invention having the above-described structure, in the normal state, the rotational force of the motor is transmitted to the planet holding plate via the speed reducing mechanism, and the clutch surface formed on the back surface of the planet holding plate is in contact with the planet holding plate. Rotate the pressed clutch plate. The clutch plate is connected to the output shaft by a method such as spline connection so as to be slidable in the axial direction, so that the rotational force is transmitted to the output shaft.

However, during work, if a reaction force (overload) exceeding the elastic force of the spring is applied to the output shaft, the projections provided on the back surface (clutch surface) of the planetary support plate will ride over the projections on the clutch plate, The clutch plate is pushed back by the height of the protrusion against the elastic force of the spring and idles, the transmission of the rotational force to the output is interrupted, and the clutch is repeatedly disengaged according to the degree of the reaction force (overload). Therefore, by changing the tightening force of the spring, it is possible to adjust the magnitude of the reaction force (overload) for blocking the rotation. Further, since the clutch plate and the output shaft supported by the bearing are coupled by a spline or the like so as to be slidable in the axial direction, even if a shock or the like is applied to the output shaft, this shock will cause a planetary reduction mechanism or It does not reach the motor.

EXAMPLES Next, specific examples of the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 is a case, and a motor 3 is attached to one end surface of the case via an attachment tool 2. Reference numeral 4 denotes a bearing that also serves as an end wall of the case 1 on the output shaft 5 side. The bearing 4 is fitted in the case 1, is fixed by screws, and has a driver bit at the tip.
An output shaft 5 for mounting a drill bit or the like is rotatably fixed by a holding metal fitting 6. An outer case 7 is provided with the motor and the case. Reference numeral 8 is a cover for covering the bearing portion, and a clutch plate 9 described later is rotatably attached to the rear end of the bearing 4 via a retainer 6 of the output shaft 5.
Also serves as a knob to adjust the elastic force of.

A planetary reduction mechanism 10 is incorporated in the case 1, and in this embodiment, three sets of planetary gear reduction mechanisms are arranged in series. That is, 11 is a sun gear connected to the output shaft 3a of the motor 3, and 12 is a plurality of planetary gears meshing with the sun gear 11. The planetary gear 12 is rotatably supported by a shaft provided on a planet holding plate 14, and the sun gear 15 of the planetary reduction mechanism of the next stage is provided on the other surface of the planet holding plate.
Are molded integrally. Reference numeral 13 is an inner gear that meshes internally with the planetary gear 12, and in this embodiment, it is integrally molded with the gear case 1 to reduce the number of parts. The above-mentioned 11 to 14 constitute a first stage planetary speed reduction mechanism.

The second stage planetary speed reduction mechanism also serves as a speed change mechanism, and the sun gear 1 integrally molded with the first stage planetary holding plate 14 is used.
5, a plurality of planetary gears 16 meshed with the sun gear, a planetary holding plate 18 having the planetary gears axially mounted thereon, and an inner gear 17 in which the planetary gears are internally meshed. The inner gear is arranged in the gear case 1 so as to be rotatable and slidable in the front-rear direction (left-right direction in the drawing). Engagement teeth 18a and 1a are formed which can mesh with the inner teeth of the inner gear, respectively. Reference numeral 19 is a slide lever for sliding the inner gear 17 in the front-rear direction, and its operating rod 19a.
Is an annular groove 17a provided in the center of the outer peripheral surface of the inner gear 17.
Is slidably fitted to the inner gear 17 by sliding the slide lever 19 in the front-rear direction so as to move the inner gear 17 to the planet holding plate 18 side or the gear case end face side (the position shown in the drawing).
Move to.

The third stage planetary reduction mechanism is a sun gear 20 integrally formed with the second stage planetary holding plate 18, a planetary gear 21 meshed with the sun gear, a planetary holding plate 23 having the planetary gear attached to the shaft, and the planetary holding plate 23. Inner gear 22 with planetary gear 21 intermeshed
It is composed of

A clutch surface 10a having a plurality of chevron projections 10b provided along the circumference is formed on the back surface of the planetary holding plate 23 of the third stage, and a hemispherical projection 9a engaging with the chevron projection 10b of the clutch surface is formed. The clutch plate 9 having the is contacted. The clutch plate 9 is slidably fitted to the splined output shaft 5, and is provided with a ball 25 by a spring 24.
It is pressed to the planet holding plate 23 side via. The elastic force of the clutch plate 9 is adjusted by a cam (not shown) formed on the inner peripheral wall of the cover 8 and a retainer fitting 26 for the spring 24.
Is performed and the cover 8 is rotated to move the pressing metal fitting 26 back and forth to adjust the degree of compression of the spring 24.

In this embodiment, the projection 10b formed on the back surface of the planet holding plate is a mountain-shaped projection and the projection 9 formed on the clutch plate.
Although a is a hemispherical protrusion, the protrusion 10b formed on the back surface of the planet holding plate may be a hemispherical protrusion and the protrusion 9a formed on the clutch plate may be a mountain protrusion.

In the above device, when the slide lever 19 is slid to the right side in the drawing (the position shown in the drawing) and the second-stage inner gear 17 is moved to the end wall side of the gear case 1, the inner teeth of the inner gear and the end face side of the gear case are The inner gear 17 is fixed to the gear case 1 by meshing with the engagement teeth 1a provided on the peripheral surface, and operates similarly to a normal planetary speed reduction mechanism.

On the other hand, when the slide lever 19 is slid to the opposite side and the inner gear 17 is moved to the planet holding plate 18 side, the inner gear 17 and the gear case 1 are disengaged, and the inner teeth of the inner gear and the engaging teeth of the planet holding plate are released. 18a meshes with.
Therefore, the planet holding plate 18, the inner gear 17, and the planetary gear 16 are integrally connected, and the revolution movement of the planetary gear 16 is blocked, so that the second stage sun gear 15 has the planetary holding plate 18
The output shaft to the next stage, which is integrally formed with the planetary support plate 18, that is, the sun gear 20, rotates at the same rotation speed as the second stage input shaft, that is, the sun gear 15. Becomes

The device of the present invention has the structure as described above, and the rotation of the motor 3 is transmitted from the output shaft 3a thereof to the planetary speed reduction mechanism 10, where it is decelerated in accordance with a predetermined speed reduction ratio, and the planetary holding on the terminal side is held. It is transmitted to the board 23. Since the axial projections 10b and 9a formed on each of the clutch surface 10a on the rear surface of the planet holding plate 23 and the clutch plate 9 are engaged with each other, the clutch plate 9 rotates together with the planet holding plate. The rotation is transmitted to the output shaft 5 that is splined with the clutch plate 9, and rotates a tool such as a driver bit or a drill bit attached to the tip of the output shaft 5.

However, when the output shaft is overloaded during use of this device, the chevron projection 10b provided on the clutch surface 10a of the planet holding plate 23 is replaced by the hemispherical projection 9a of the clutch plate 9.
The clutch plate 9 is pushed back against the elastic force of the spring 24 by the height of this projection and idles, the transmission of the rotational force to the output is interrupted, and the clutch is released according to the degree of the reaction force (overload). Is repeated intermittently. Therefore, by changing the tightening force of the spring, it is possible to adjust the magnitude of the reaction force (overload) for blocking the rotation. Further, since the clutch plate and the output shaft supported by the bearing are connected by a spline or the like so as to be slidable in the axial direction, even if a shock or the like is applied to the output shaft, the shock is applied to the planetary reduction mechanism. Or to the motor.

Thus, in the present invention, when a reaction force of a predetermined value or more is applied to the output shaft, even if the motor and the planetary speed reduction mechanism idle and the output shaft is shocked, It is equipped with a mechanism that is not directly transmitted to the motor, and is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the electric rotating tool of the present invention. 1 ... Gear case, 3 ... Motor 4 ... Bearing, 5 ... Output shaft 9 ... Clutch plate, 9a ... Projection 10 ... Planetary reduction mechanism 10a ... Clutch surface, 10b ... Projection 23 ... Planet holding Board

Claims (1)

[Claims] 1. A clutch mechanism for an electric rotary tool having a planetary reduction mechanism with an irregular mechanism in a gear case, wherein either a mountain-shaped protrusion or a hemispherical protrusion is provided on the rear surface of a planet holding plate on the terminal side of the planetary reduction mechanism. A clutch surface having a plurality of projections, which is one, is formed, and other than a mountain-shaped projection or a hemispherical projection that engages with the projection formed on the clutch surface, other than the projection formed on the back surface of the planet holding plate The clutch plate with the protrusion is pressed by a spring whose pressure level can be adjusted by a cam formed on the inner peripheral wall of the cover rotatably attached to the outer case, and the clutch plate is axially moved with respect to the output shaft. A clutch mechanism for an electric rotating tool, which is coupled so as to be slidably displaced.