JPH09103971A - Motor-driven impact wrench - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driven impact wrench suited for weight reduction and miniaturization by allowing passage of an anvil if reaction not smaller than a certain value is transmitted from the bit side to a clutch part, while allowing a pusher to force the anvil inward against the elastic force of a spring, so that the rotational force of a hammer part is allowed to escape. SOLUTION: When a screw is fastened to some degree, the reaction from the screw increases and the amount of rotation of a clutch part 3 rotated thereby gradually decreases, but the hammer part 2 tends to keep rotating with the same torque unless operation of an electric motor is stopped. As a result, the hammer part 2 that tends to keep rotational action passes below an anvil 22 as a pusher 21 is forced in against the elastic force of a spring 22, since the pusher 21 strikes an anvil 3A in such a manner as to strongly collide against it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric impact wrench that rotates a bit by driving force of an electric motor to tighten a screw.

[0002]

2. Description of the Related Art An electric impact wrench utilizing the driving force of a motor is known as one of electric tools for tightening screws. This electric impact wrench is, for example, as shown in FIG. 4, a sun gear 101 that rotates integrally with the output shaft 100 side of an electric motor (not shown), and internal teeth 10 of an internal gear 102 that meshes with the sun gear 101.
2A, a torque increasing mechanism 104 provided with a planetary gear 103 or the like that rotates and rotates, a clutch shaft 103B having one end fixed to a rotating body 103A that rotatably attaches the planetary gears 103 to each other, and the clutch. A rigid ball 105 movably inserted between a groove 103C formed on the other end side of the shaft 103B and a groove formed on an inner peripheral surface of a hammer clutch 107 described later, and the rigid ball 105.
The rotational force is transmitted in a state in which the rigid sphere 105 is pressed and sandwiched from the left and right in the horizontal direction by the elastic force of the compression spring 106 provided between the rotating body 103A and the other end side of the clutch shaft 103B via It is known that a hammer clutch 107, an anvil 108 that is rotated by a hook that is locked and struck by a convex portion 107A of the hammer clutch 107, and a bit 109 that rotates integrally with the anvil 108 are known.

[0003]

However, the electric impact wrench having such a structure has the following drawbacks. It is necessary to make a groove with a unique curved shape in both the hammer shaft and the hammer clutch, which is troublesome to process, and the clutch shaft and spring occupy a relatively large space along the rotation axis direction. Being a factor that hinders miniaturization.

In view of the above circumstances, the present invention is lightweight and
It is an object of the present invention to provide an electric impact wrench suitable for downsizing.

[0005]

That is, according to the invention of claim 1, the driving force from the electric motor is transmitted to and rotated by the hammer portion via the torque increasing mechanism, and the clutch portion is driven by the rotating force of the hammer portion. In an electric impact wrench that rotates a bit while striking it to tighten a screw, a pusher is provided on the hammer portion, and an anvil extending in an arm shape in a radial direction is provided on the clutch portion. When the protruding pusher is struck, the rotational force from the hammer portion is transmitted to the clutch portion, and when a reaction force of a certain value or more is transmitted from the bit side to the clutch portion, the pusher causes the spring to move. The anvil passes through while retracting inward against the elastic force, and the rotational force of the hammer portion is released.

Further, according to the invention of claim 2, the torque increasing mechanism is an internal gear which is immovable with respect to the electric impact wrench main body side while meshing with the sun gear rotated by the driving force of the electric motor and the sun gear. And a planetary gear that rotates along the inner teeth of the.

[0007]

According to the present invention, the pusher is provided on the hammer portion so as to be movable back and forth so as to project by the elastic force of the spring, and the clutch portion has an arm-like shape on which the pusher is struck. When the hammer is rotated by the rotational driving force from the electric motor, the pusher provided on the rotating hammer strikes the anvil of the clutch, thereby the anvil and the clutch provided with the anvil. Rotates, and the bit integrated with this also rotates to tighten the screw.

When the screw is tightened to a certain extent, a reaction force acts on the clutch portion from the screw side to stop the rotation of the clutch portion. At this time, the hammer driving portion is rotated by the rotational driving force on the electric motor side. Since the pusher strikes the anvil, the anvil is pushed inside and moves backward, and the hammer can rotate while the pusher passes below the anvil.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic perspective view showing an electric impact wrench according to the present invention. This electric impact wrench has a torque increasing mechanism 1
A hammer portion 2 and a clutch portion 3. In the figure, reference numeral 4 is an output shaft of the electric motor (motor), and 5 is a bit.

The torque increasing mechanism 1 is, as shown in FIG.
The sun gear 11 fixed to the tip of the output shaft 4 and the two gears that mesh with the sun gear 11 and rotate along the inner peripheral surface of the internal gear 13 to be described next (the number is not limited to two). However, it may be three or more.) And an internal gear 13 fixed to an electric impact wrench body casing (not shown).

The hammer portion 2 is formed in a substantially disc shape (or a column shape), and has a planetary gear 12 rotatably attached (immovable in the revolution / rotation direction).
It is adapted to rotate by the rotation operation (revolution operation) of 2. Further, in the hammer portion 2, the mounting shaft 11A of the sun gear 11 is rotatably inserted in the rotation center portion, and the rotation shaft 2C is projectingly provided in the rotation center portion on the opposite surface side.

Further, the hammer portion 2 has a pair of pushers 21 (at a point symmetrical position 180 degrees apart) on the surface opposite to the mounting surface of the planetary gear 12 (right surface in FIG. 2).
(See FIG. 2) is provided so that it can move back and forth. When the screw is tightened, the pusher 21 functions as a hammer and strikes the anvil 3A of the clutch portion 3. As shown in FIGS. 1 and 2, the pusher 21 of this embodiment has
It is formed into a substantially fan-shaped outer shape and is slidably provided in a slide hole 2A of a hammer portion 2. A compression spring 22 having an appropriate elastic force F is interposed in the slide hole 2A,
The pusher 21 is projected from the right side in FIG.

As shown in FIG. 2, the clutch portion 3 has a pair of anvils 3A projecting at a point-symmetrical position in a (radial) direction perpendicular to the rotation axis direction, and a hammer portion at the center of rotation. Rotating hole 3 for rotatably inserting the rotating shaft 2C of 2
C is provided (on the contrary, a rotation hole may be provided on the clutch part side), and when the anvil 3A is hit by the pusher 21, the rotational force of the hammer part 2 is transmitted and the rotation shaft 2C is moved. It is designed to rotate as the center of rotation. Further, a bit 5 (see FIG. 1) is fixed to a shaft body 3B provided coaxially with the rotation hole 3C of the clutch portion 3, and the hammer portion 2
The rotational force from is transmitted to the bit 5.

In addition, when screwing in the electric impact wrench, the screw is completely tightened,
When a reaction force of a certain value or more is transmitted from the bit 5 side to the output shaft 4 side in reverse, that is, the elastic force of the compression spring 22 is retracted to the inner side to allow passage and rotation of the convex portion 3A. However, the rotational force from the hammer section 2 is released.

Therefore, according to this embodiment, as shown in FIG. 1, the rotational driving force from the electric motor is transmitted to the sun gear 11 to which the output shaft 4 is fixed, and the planetary gear 12 meshes with the sun gear 11. By the rotating action of, the hammer portion 2 provided with the planetary gear 12 rotates in the same direction. Therefore, the pusher 21 of the hammer portion 2 strikes the anvil 3A,
As a result, the clutch portion 3 rotates in the same direction, so that the screw is tightened.

When the screw is tightened to some extent, the reaction force from the screw increases, and the rotation amount of the rotating clutch portion 3 gradually decreases, but the operation of the electric motor stops. Unless otherwise, the hammer portion 2 still tries to rotate with the same rotation torque. As a result, the hammer portion 2 that tries to continue the rotation operation is
As shown in FIG. 3, the pusher 21 is forcibly pushed into the anvil 22 against the elastic force of the spring 22 because the 1 hits the anvil 3A strongly.
It will pass below.

[0017]

As described above, according to the present invention, the pusher element is provided on the hammer portion so as to be movable back and forth so as to project by the elastic force of the spring, and the pusher element is pushed on the clutch portion. It is equipped with an arm-shaped anvil on which the moving element is struck, and when the hammer part rotates due to the rotational driving force from the electric motor, the pusher provided on this rotating hammer part strikes the anvil of the clutch part. The clutch part rotates, the bit also rotates, and the screw is tightened.The rotating force generated can be easily adjusted by changing the elastic force of the spring. In other words, it was necessary in the past. No big clutch springs or clutch shafts are needed, and no hammers of any kind to get the torque. Further, since it is possible to reduce the weight and size by that amount, it is possible to provide the one excellent in portability.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an electric impact wrench according to the present invention.

FIG. 2 is a sectional view of the electric impact wrench.

FIG. 3 is a sectional view showing the action of the electric impact wrench.

FIG. 4 is a side view showing a conventional example.

[Explanation of symbols]

 1 Torque Increasing Mechanism 11 Sun Gear 12 Planetary Gear 13 Internal Gear 2 Hammer Part 21 Pusher 22 Spring 3 Clutch Part 3A Anvil 5 Bit

Claims (2)

[Claims] 1. An electric impact in which a driving force from an electric motor is transmitted / rotated to a hammer portion via a torque increasing mechanism, and the rotating force of the hammer portion strikes a clutch portion to rotate a bit to tighten a screw. In the wrench, the hammer is provided with a pusher, and the clutch portion is provided with an arm-shaped anvil extending in the radial direction. When the anvil is struck by a pusher protruding from the hammer, the hammer is used. When the rotational force from the portion is transmitted to the clutch portion and a reaction force of a certain value or more is transmitted from the bit side to the clutch portion, the pusher pulls inward against the elastic force of the spring and the anvil moves. Pass through
An electric impact wrench characterized in that the rotational force of the hammer portion is released. 2. A planetary gear in which a torque increasing mechanism rotates along the inner teeth of an internal gear that is stationary with respect to the electric impact wrench main body side while meshing with the sun gear that rotates by the driving force of the electric motor. The electric impact wrench according to claim 1, further comprising: