JPH0425107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a transmission device for an electric screwdriver that outputs a transmission output via a planetary gear mechanism.

(b) Conventional technology The small electric screwdrivers that have been used in the past are mainly used for relatively light-load turning operations with high-speed, low-torque rotation, but depending on the conditions of use, small electric screwdrivers may be used. In recent years, electric screwdrivers that are capable of low-speed, high-torque rotation have been provided, as there is a desire for a screwdriver that can produce high torque output even at low speeds.

(c) Problems to be solved by the invention However, in this case, due to the small size, there is a limit to the torque output, making it impossible to obtain the desired high torque output and not being applicable to a wide range of rotational work, resulting in poor work efficiency. was forced to decline.

In addition, the output structure has a problem that the transmission mechanism and its transmission changeover mechanism require many gears, making the structure complex and large, resulting in high cost.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide a transmission device for an electric screwdriver that can easily obtain different transmission outputs of high speed and low speed in one direction of forward or reverse rotation without complicating the structure. .

(d) Means for Solving the Problems This invention includes a sun gear connected to the main shaft of a motor, a planetary gear meshing with the sun gear, and an internal gear meshing with the planetary gear, and outputs a gear change output from a carrier that pivotally supports the planetary gear. The electric tribar transmission is equipped with a planetary gear reduction mechanism, and the slide gear meshing with the internal gear is slid in the axial direction of the high-speed transmission side, which is the planetary gear side, and in the opposite axial direction of the low-speed transmission side. The slide gear is provided with an engaging recess on the planetary gear side side surface thereof, which engages with the shaft of the planetary gear to lock the internal gear and the planetary gear when the slide gear slides toward the high-speed transmission side. an engaging portion for fixing rotation of the slide gear when the slide gear slides toward the low-speed transmission side is formed between the slide gear and a fixing portion opposing the slide gear; of,
The transmission device for an electric screwdriver is characterized in that it is provided with speed switching means for switching between the high-speed transmission sliding position and the low-speed transmission sliding position.

(E) Functions and Effects of the Invention According to the present invention, by engaging the engagement recess of the slide gear with the shaft of the planetary gear, locking the internal gear and the planetary gear, and rotating them together. , high-speed conduction output is obtained through a planetary gear that revolves at high speed,
In addition, if the above-mentioned lock is released and the slide gear is fixed to the fixed part by the engaging part, the internal gear is fixed and the planetary gear can revolve and rotate, and the planetary gear will naturally rotate at a low speed in the planetary gear reduction mechanism. As a result, a low-speed conduction output is obtained, and these high-speed conduction output and low-speed conduction output are obtained when the motor main shaft rotates in one direction, normal rotation or reverse rotation.

By appropriately switching and using such high and low speed conduction outputs, so-called different types of torque outputs, to suit the required load of the rotated body at the start and end of rotation during forward rotation, for example, one electric The driver performs a series of rotation operations from beginning to end, making it a highly efficient driver.

Moreover, the above-mentioned switching of different torques can be achieved regardless of whether the rotation direction is forward or reverse.

Furthermore, since the speed can be changed only by locking and unlocking the internal gear and the planetary gear, the speed change mechanism is simple and the speed switching means for these speed changes can be easily obtained.

(F) Embodiment of the Invention An embodiment of the invention will be described in detail below based on the drawings.

The drawing shows an electric screwdriver, and in FIG. 1, an electric screwdriver 1 has a chuck 2 at its tip, and this chuck 2 holds various rotary tools (not shown).

The casing 3 is formed into a cylindrical shape, and an operating tube 4 for setting the load of the torque limiter is provided at the tip of the casing 3.
The load on the output shaft is set by rotating the operation cylinder 4 in accordance with the scale. A gripping part 5 is provided in a row at the middle lower part of the casing 3, and a trigger 6 is provided on the front surface of the base of the gripping part 5, and this trigger 6 turns the power on and off.

A forward/reverse rotation switch 7 for the forward/reverse motor is provided on the side surface of the intermediate portion of the casing 3, and by operating this switch 7 in the vertical direction, the motor can be switched between forward rotation, stop, and reverse rotation. In addition, this switch 7
Since the inside of the switch 7 is formed into a ring shape, the switch 7 is also provided on the opposite side of the casing 3.

This electric screwdriver 1 uses a battery as a power source, and the battery is provided so as to be housed in the rear end of the casing 3 as appropriate.

In FIG. 2, the output of the forward/reverse motor 8 fixed in the casing 3 is transmitted to a first planetary gear reduction mechanism 9 equipped with variable speed outputs of high speed and low speed, and a constant speed motor 8 sequentially connected to the subsequent stage. The second, which decelerates to
The power is transmitted to the output shaft 11 via the third planetary gear reduction mechanism 10, and as a result, the chuck 2
is rotated.

Each of these speed reduction mechanisms 9, 10, .
is housed in an inner gear case 13 fixed inside an outer gear case 12, opposite to the motor 8.

This first planetary gear reduction mechanism 9 has three first planetary gears 16 equally spaced in the circumferential direction and meshes with a first sun gear 15 that is pivotally attached to the end of the main shaft 14 of the motor 8. 1 internal gear 17 and revolution is permitted.

Each of the gear shafts of the first planetary gear 16 described above is fixed to the first carrier 18, and these gears 1
The revolution output of 6 is transmitted to the second planetary gear reduction mechanism 10 at the subsequent stage via the intermediate output shaft 19 which is integrated with the first carrier 18.

A slide gear 20 that slides in the axial direction of the motor 8 is fitted onto the main shaft 14 of the motor 8, and this slide gear 20 meshes with the first internal gear 17, and has a protruding portion of the first planetary shaft 22 on one end surface. 21, and a permanent magnet 24 and a locking protrusion 25 on the other end surface.

The above-mentioned protrusion 21 has a conical tip and serves to generate a sliding action such that the protrusion 21 is lightly fitted into the corresponding recess 23 and easily removed.

The above-mentioned permanent magnet 24 is integrally fitted into the exposed center end face of the slide gear 20, and the permanent magnet 26 is similarly exposed on the end face of the boss portion 8a on the motor 8 side facing the slide gear 20. The permanent magnets 2 of both of these
4 and 26, and the slide gear 20 is slid in any direction along the main shaft 14 by this magnetic repulsion and the action of a magnetic circuit, which will be described later.

The above-mentioned opposing permanent magnets 24 and 26 are set in a magnetic repulsion state with the same magnetic poles facing each other, so that the slide gear 20 is normally magnetically biased in a direction away from the motor 8 side, and the slide gear The protrusion 21 of the first planetary shaft 22 is fitted and locked in the end face recess 23 on the opposite side of the gear 20, thereby locking the rotation of the first planetary gear 16. Therefore, if power is transmitted in this state, a high-speed transmission output will be obtained in which only the high-speed revolution of the first planetary gear 16 is permitted.

When obtaining a low-speed conduction output, the slide gear 20 slides and both permanent magnets 24, 2
It is provided when 6 are in a state of facing each other,
In this case, the locking protrusion 25 of the slide gear 20 is
The slide gear 20 is held in a fixed state in which rotation is stopped by being locked by a locking portion 27 formed on the end face on the motor 8 side, and at this time, the slide gear 20 is unlocked from the first planetary shaft 22. , rotation of the first planetary gear 16 is allowed,
By transmitting power in this state, relatively low-speed transmission output can be obtained.

The above-mentioned locking projection 25 is provided with a spring so as to be movable forward and backward on its corresponding side, and a locking portion 27 corresponding thereto is provided.
The structure is designed to promote stable shock absorption when the vehicle is locked with the vehicle.

The sliding operation of the slide gear 20 described above is performed by an auxiliary coil 29 for guiding the slide gear, which is wound around the outer circumference of the boss portion 8a of the main shaft 14 via an annular frame 28.
This is done by exciting the motor case 8b, the inner gear case 13, and the annular frame 2, which are electrical conductors, to electrically connect the main coil inside the motor 8.
8, first internal gear 17, slide gear 2
A magnetic circuit is constructed that circulates around a so-called auxiliary coil 29 that flows through both the permanent magnets 24 and 26 and the boss portion 8a, and the auxiliary coil 29 is excited by the generation of this magnetic circuit.

By the way, when the auxiliary coil 29 is excited, the magnetic repulsion of the permanent magnets 24 and 26 occurs when the load on the rotated body increases during use of the electric screwdriver 1 and a large current is generated in the motor 8. Auxiliary coil 2 is generated by generating a magnetic circuit larger than the force.
9 is excited, and the slide gear 20 is slid by the exciting action of this magnetic circuit.

It should be noted that when separating the slide gear 20 and the boss portion 8a, it may be possible to use a spring instead of a permanent magnet, but in this case, the frictional resistance at the supporting contact surfaces at both ends of the spring is high. Therefore, it is not preferable to use a permanent magnet.

The second planetary gear reduction mechanism 10 described above includes a second sun gear 30 that is pivotally attached to an intermediate output shaft 19, three second planetary gears 31 meshing with this gear and equally spaced in the circumferential direction, and second planetary gears 31. The second internal gear 32 meshes with the second planetary shaft 33, and the second carrier 34 is integrated with the second planetary shaft 33.

Then, the decelerating rotational force from the intermediate output shaft 19 is further decelerated through each of these gears and the power is transmitted to the second carrier 34, and the third planetary gear reduction mechanism (not shown) is transmitted through the second carrier 34. are arranged in series so that the output shaft 11 has a predetermined deceleration rotation speed.

A ball locking protrusion 35 is formed around the side surface of the second internal gear 32 facing the motor 8, and a ball 37 supported by a ball support plate 36 abuts between these protrusions 35. This ball 37 is biased toward the ball locking protrusion 35 by a spring 39 via a receiving plate 38, thereby forming a ball clutch 40.

The above-mentioned ball clutch 40 has a spring 39
The trilimiter can be set by adjusting the biasing force of the spring 39, and the biasing force of the spring 39 is adjusted by adjusting the amount by which the second internal gear 32 is moved toward the ball side.

In the figure, 41, 42, 43 are spacers, and 44 is a bearing.

FIG. 3 shows an electric circuit, in which a forward/reverse changeover switch 7 controls the forward/reverse rotation by switching the polarity of the forward/reverse motor 8. The auxiliary coil 29 is connected to the battery 4
5 and the trigger 6.

When tightening bolts, nuts, etc. using an electric screwdriver configured in this way,
The forward/reverse selector switch 7 is operated from the neutral stop position to the desired forward or reverse rotation direction, and then the trigger 6 is turned on. Motor 8 is activated by operating trigger 6.
When the motor rotates in the forward or reverse direction, the output from the motor 8 is sequentially transmitted to the output shaft 11 via the first, second, . . . planetary gear reduction mechanisms 9, 10, .

At this time, in the first planetary gear reduction mechanism 9,
The slide gear 20 is magnetically energized and is in a state of high-speed transmission output in which the rotation of the first planetary gear 16 is locked, and under high-speed rotation conditions suitable for the initial tightening of so-called bolts that allow rotation under light loads. Perform the tightening operation and tighten at once.

Then, as the fastening load gradually increases, the auxiliary coil 29 is automatically excited, and accordingly, the slide gear 20 slides based on the generation of the magnetic circuit, and the first The planetary gear 16 is unlocked and allowed to rotate, rotates at a low speed, and is switched to a sufficiently decelerated low-speed, high-torque transmission output. Therefore, when tightening a bolt or the like, the high torque required at the end of tightening can be automatically obtained, and a rotation operation suitable for the tightening operation can be obtained with one electric screwdriver.

In the above-mentioned embodiment, the tightening operation of a rotated object such as a bolt is shown as an example, but this is not limited to the tightening operation of a rotated object such as a bolt. It can be applied to body rotation operations. Further, although the speed change is automatically performed by excitation of the coil, it may be configured to be changed manually.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a side view of an electric screwdriver, FIG. 2 is an enlarged longitudinal cross-sectional view of a main part of the transmission, and FIG. 3 is an electric circuit diagram thereof. DESCRIPTION OF SYMBOLS 1... Electric screwdriver, 9... First planetary gear reduction mechanism, 15... First sun gear, 16... First planetary gear, 17... First internal gear,
18...first carrier, 20...slide gear,
22...first planetary shaft, 23...recess, 2
4, 26... Permanent magnet, 25... Locking protrusion, 27
... Locking part, 29 ... Auxiliary coil.

Claims (1)

[Scope of Claims] 1. An electric motor including a sun gear connected to the main shaft of the motor, a planetary gear meshing with the sun gear, and an internal gear meshing with the planetary gear, and a planetary gear reduction mechanism that extracts a variable speed output from a carrier that pivotally supports the planetary gear. The transmission of the tri-bar is provided with a slide gear that meshes with the internal gear so as to be slidable in an axial direction on a high-speed transmission side, which is the planetary gear side, and in an axial direction on the opposite low-speed transmission side, and the slide gear meshes with the internal gear. On the side of the planetary gear side, when the slide gear slides to the high speed transmission side,
An engagement recess is formed that engages with the shaft of the planetary gear to lock the internal gear and the planetary gear, and an engagement that fixes the rotation of the slide gear when the slide gear slides toward the low-speed transmission side. Department,
A speed change means for an electric screwdriver, comprising: a speed switching means formed between a slide gear and a fixed part facing the same, and for switching the slide gear between the high-speed transmission sliding position and the low-speed transmission sliding position. Device.