JPS6229660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a transmission device for an electric screwdriver that automatically outputs a transmission output via a planetary gear mechanism.

(b) Background of the Invention The small electric screwdrivers that have been used in the past are mainly used for relatively light-load rotating operations with high-speed, low-torque rotation, but depending on the conditions of use, small-sized 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.

However, in this case, because of its small size, there was a limit to the torque output due to its configuration, and the desired high torque output could not be obtained. For this reason, not only was it inapplicable to a wide range of rotational work, but work efficiency was significantly lowered, as it required a gear change operation each time the gear was changed. Further, the structure has a problem that the transmission mechanism and its transmission switching mechanism require many gears, making the structure complex and large, resulting in high cost.

(c) Purpose of the Invention Therefore, the present invention provides an electric screwdriver that can automatically switch between high-speed and low-speed disparate transmission outputs according to the load without requiring a speed change operation or complicating the structure. The purpose is to provide a transmission.

(D) Summary of the Invention This invention makes it possible to extract both high-speed conduction output and low-speed conduction output through a compact planetary gear mechanism that produces high output, and to automatically output it as appropriate according to the operating load. It is characterized by a transmission device for an electric screwdriver that can switch between high and low speed transmission output.

(E) Effects of the Invention According to the present invention, a slide gear that meshes with an internal gear is provided so as to be able to engage and disengage from the shaft of a planetary gear, and the slide gear is caused to perform the magnetic repulsion of a permanent magnet. As a result, the internal gear and the planetary gear are fixed by magnetically biasing the slide gear in one direction, and by the integral rotation of these gears, the planetary gear can revolve at high speed and a high-speed transmission output can be obtained. In addition, when the load on the motor increases and a large current flows through the motor, the auxiliary coil is naturally excited, and the excitation action of this coil causes the slide gear to slide in the other direction against the magnetic force of the permanent magnets, thereby aligning it with the shaft of the planetary gear. The engagement of the planetary gear is released to allow rotation of the planetary gear. Thereby, the planetary gear becomes a planetary gear reduction mechanism that rotates at a low speed and can obtain a low-speed transmission output.

Therefore, when using an electric screwdriver, a constant voltage current flows through the motor during rotation operations with relatively light loads, making it suitable for relatively high-speed rotated objects under high-speed, low-torque transmission output. You can perform rotational operations. Furthermore, when a high load is applied to the motor, a large current flows through the motor, and based on this, the slide gear automatically slides to change speed, thereby providing a low-speed, high-torque transmission output rotational operation. In this way, the rotation operation can be performed with the required torque output according to the conditions of use, which is particularly effective when torque conversion is required at any time.
A single electric screwdriver performs a series of turning operations from beginning to end, making it a highly efficient and highly capable screwdriver.

Moreover, not only is the gear changeover mechanism automatic, but
Since the switching mechanism is operated only by sliding the slide gear, it can be provided with a simple configuration.

(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 grip part 5 is connected to the middle lower part of the casing 3, and a trigger 6 is provided on the front surface of the base of the grip 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. Second, slow down to
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 reduction mechanisms 9, 10... is housed in an outer gear case 12 fitted into the casing 3, and the above-mentioned first planetary gear reduction mechanism 9 is
The motor 8 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.

The above-mentioned first planetary gear 16 has each gear shaft 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 an intermediate output shaft 19 that 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 end face of the central portion of the slide gear 20 in an exposed state, and a permanent magnet 26 is similarly exposed on the end face of the boss portion 8a on the side of the motor 8 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 planetary shaft 20, and the first
The rotation of the planetary gear 16 is locked. 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 carved on the end surface 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, which is a conductor, the inner gear case 13, the annular frame 28, and
first internal gear 17, slide gear 20,
A magnetic circuit is constructed that goes around a so-called auxiliary coil 29 that flows through both permanent magnets 24, 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, when the load on the rotated body increases and a large current is generated in the motor 8 as a result of this, when the electric screwdriver 1 is used, the magnetic repulsion force is greater than the magnetic repulsion force of the permanent magnet. A magnetic circuit is generated to excite the auxiliary coil 29, and the slide gear 20 is slid by the excitation 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 torque limiter 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,
Operate the forward/reverse selector switch from the neutral stop position to the desired forward or reverse rotation direction, and then turn on the trigger 6. When the motor 8 rotates in the forward or reverse direction by operating the trigger 6, the output from the motor 8 is transmitted to the output shaft 11 through the first, second, etc. planetary gear reduction mechanisms 9, 10, etc. Ru.

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. Tighten it all 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.

[Brief explanation of the drawing]

The drawings show an embodiment of the invention, and FIG. 1 is a side view of an electric screwdriver. FIG. 2 is an enlarged vertical sectional view of the main parts of the transmission. FIG. 3 is its electrical circuit diagram. 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, 24, 26... Permanent magnet,
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. A transmission device for a driver, which is engaged with the internal gear and slides to engage and disengage from the shaft of the planetary gear while maintaining this engagement, and when disengaged, the rotation of the slide gear is stopped. a pair of permanent magnets with the same magnetic poles facing each other on mutually opposing surfaces of the slide gear and the boss portion of the motor; a magnetic circuit including the slide gear; form,
An auxiliary coil that excites a magnetic circuit based on the increase in motor load and a large current flowing through the motor, and slides the slide gear in the direction of disengaging the planetary gear shaft against the magnetic force of the permanent magnet. Equipped with an electric screwdriver transmission.